文档库 最新最全的文档下载
当前位置:文档库 › 文献72

文献72

Electrocatalytic oxidation of glucose at gold–silver alloy,silver

and gold nanoparticles in an alkaline solution

Masato Tominaga *,Toshihiro Shimazoe,Makoto Nagashima,Hideaki Kusuda,

Atsushi Kubo,Yutaka Kuwahara,Isao Taniguchi *

Department of Applied Chemistry and Biochemistry,Faculty of Engineering,Kumamoto University,2-39-1Kurokami,Kumamoto 860-8555,Japan

Received 11November 2005;received in revised form 2February 2006;accepted 16February 2006

Available online 19April 2006

Abstract

Gold,silver and gold–silver alloy nanoparticles capped with decanethiolate monolayer shells (DT-Au,DT-Ag and DT-Au/Ag)were synthesized,with core sizes 2.3(±1.0),3.3(±1.0)and 2.0(±1.0)nm,respectively.To activate the synthesized nanoparticles for the elect-rocatalytic oxidation of glucose,nanoparticles were treated at 300°C for 2h.Heat-treated nanoparticles surfaces were characterized by FT-IR,X-ray photoelectron spectroscopy (XPS),thermogravimetric analysis (TGA),scanning electron microscopy (SEM)and cyclic voltammetry (CV).The elimination of C–H alkyl chains and thiolates from DT capped Au and Au/Ag nanoparticles was evident post heat-treatment by TGA,FT-IR and XPS investigations.In DT-Ag nanoparticles,C–H chains from DT were eliminated by heat-treat-ment,though thiolate was still present on nanoparticle surfaces.However,the thiolate from DT was eventually removed by further oxi-dation and reduction cycle treatments in an alkaline solution.After heat-treatment at 300°C for 2h,the surface content ratio of Au and Ag changed from Au:Ag(84:16)to Au:Ag(73:27).This tendency to increase the surface content ratio of Ag after heat-treatment was also observed in other Au–Ag alloy nanoparticle content ratios.Results from cyclic voltammograms at Au/Ag nanoparticles modi?ed PFC electrodes in H 2SO 4and NaOH solutions indicated that the distribution of Au and Ag atoms of Au/Ag nanoparticles on nanocrystal surfaces is homogeneous.Electrocatalytic peaks for glucose oxidation in a 0.1mol dm à3NaOH solution were observed around à0.4and 0.4V (vs.Ag/AgCl)at heat-treated Au nanoparticle modi?ed carbon electrode and around à0.4and 0.6V at heat-treated Au/Ag nanoparticle modi?ed electrode,which correspond to the oxidation of glucose and further oxidation of gluconolactone generated by the ?rst oxidation peak (à0.4V),respectively.It is interesting to note that the catalytic current at Au/Ag nanoparticle modi?ed electrodes was observed from ca.à0.75V,which represents a negative potential shift of ca.0.1V compared to that at Au nanoparticle modi?ed electrodes.This result indicates that Au–Ag alloy nanoparticles are e?ective catalysts for the electrocatalytic oxidation of glu-cose.At both Au and Au/Ag nanoparticles,aldose-type monosaccharides showed catalytic oxidation peaks in an alkaline solution,how-ever ketose-type monosaccharides did not show any catalytic peaks in the potential region of à0.8$0.8V.After the controlled-potential electrolysis at a potential of à0.3V,gluconolactone (or gluconate,a two-electron oxidation product)was only detected at a current e?ciency of 100%at Au and Au/Ag nanoparticles modi?ed carbon electrodes.In the case at 0.3V,oxalate (an 18-electron oxidation product)and gluconolactone as the main product were detected at Au nanoparticle modi?ed electrodes,and formate (a 12-electron oxidation product)in addition to oxalate and gluconolactone as the main products were detected at both Au/Ag and Ag nanoparticles modi?ed electrodes.These results indicate that the catalytic selectivity at a potential of 0.3V would be strongly governed by silver atoms containing Au/Ag nanoparticles surfaces.ó2006Elsevier B.V.All rights reserved.

Keywords:Electrochemistry;Oxidation;Glucose;Nanoparticle;Alloy;Gold;Silver;Modi?ed electrode

1.Introduction

The electrocatalytic oxidation of glucose is an attractive research ?eld for applications in glucose–oxygen fuel cells

0022-0728/$-see front matter ó2006Elsevier B.V.All rights reserved.doi:10.1016/j.jelechem.2006.02.018

*

Correspondings authors.Tel./fax:+81963423656.

E-mail address:masato@gpo.kumamoto-u.ac.jp (M.Tominaga).

https://www.wendangku.net/doc/c517262460.html,/locate/jelechem

Journal of

Electroanalytical

Chemistry

and for the development of glucose sensors for medical and food industries[1–5].Gold is an attractive metal for the oxidation of glucose.The electrocatalytic oxidation of glu-cose has been examined extensively[1–3].Recently,a single crystal gold modi?ed with catalytically active metals(such as Ru,Ag,Cu,Pt,Pd and Cd)by under-potential deposi-tion(UPD)was studied for the oxidation of sugar.The e?ective electrochemical oxidation of glucose was demon-strated at Ag-UPD single crystal gold electrodes[5,6]. These previous reports suggest that multi component sur-face compositions are expected to produce synergistic e?ects to achieve high activity and selectivity.

Recently,gold nanoparticles have been studied exten-sively for the design and fabrication of catalysts,an enhancement of catalytic activity or selectivity,and the large surface area-to-volume ratios[7–23],because the cat-alytic properties of gold nanoparticles with a few nanome-ter cores could change completely due to particle phase transitions,i.e.,atomic to metallic phase property changes over this size range[7–10,13,14,16,20–22].In a previous investigation,we found that the catalytic activity on the controlled-potential electrolysis of glucose was improved by use of carbon electrodes modi?ed with$2nm core sized gold nanoparticles as catalysts,and electrolysis products were determined along with current e?ciencies[24,25]. To our best knowledge,however,the glucose oxidation has not been previously investigated by use of gold-based bimetallic nanoparticles as catalysts.Nanoparticles with multi component surface compositions would be expected to produce synergistic e?ects,which in the case of catalysts would provide high activities and selectivity for the electro-catalytic oxidation of glucose.

In the present study,Au,Ag and Au–Ag alloy nanoparti-cles capped with decanethiol monolayer shells were synthe-sized.We selected Ag for gold-based alloy nanoparticles, because Ag atom modi?ed gold electrodes by UPD showed the e?ective electrochemical oxidation of glucose[5,6].To activate the synthesized nanoparticles prior to the examina-tion of the electrocatalytic oxidation of glucose,nanoparti-cles were treated at300°C for2h.Nanoparticles surfaces after heat-treatment were characterized by FT-IR,X-ray photoelectron spectroscopy(XPS),thermogravimetric anal-ysis(TGA),scanning electron microscopy(SEM)and cyclic voltammetry(CV).Electrocatalytic activities and electroly-sis product selectivities were investigated by using heat-acti-vated nanoparticles.The results obtained indicate that Au–Ag alloy nanoparticles are also e?ective catalysts for the electrocatalytic oxidation of glucose.Furthermore,a strong metal composition dependence of nanoparticles on electrolysis oxidation products was observed at Au and Au/Ag nanoparticles at electrolysis potential of0.3V,which indicate that catalytic selectivity would be strongly governed by Ag atoms containing Au/Ag nanoparticle surfaces.Our preliminary results suggest the design and preparation of cat-alysts with bifunctional properties are important in achiev-ing high activities and selectivities in the electrocatalytic oxidation of glucose,and for applications using glucose–oxygen fuel cells,and for the development of glucose sensors for the medical and food industries.

2.Experimental section

2.1.Chemicals

Hydrogen tetrachloroaurate(III)trihydrate(HAuCl4 3H2O,99.9+%),sodium borohydride(NaBH4,99.995%) and decanethiol(DT,96%)were purchased from Aldrich and used as receive.Tetraoctylammonium bromide (TOAB,98%)and silver nitrate(AgNO3,99.8%)were obtained from Lancaster and Nacalai Tesque(Japan), respectively,and used as receive.Water was puri?ed with a Millipore Milli-Q water system.Other chemical reagents used were of analytical grade.

2.2.Preparation of monometallic gold and silver nanoparticles and gold–silver alloy nanoparticles The synthesis of gold nanoparticles with$2nm cores capped with decanethiolate monolayer shells(DT-Au nanoparticles)were synthesized by Schi?rin’s two-phase synthesis protocol[11,12].Brie?y,for the synthesis of DT-Au,0.75mmol HAuCl4was dissolved in25mL of a puri?ed water solution.To transform AuCl4-from aque-ous phase to toluene phase,an HAuCl4aqueous solution was added to an80mL toluene solution containing tetra-octylammonium bromide(TOAB,

3.0mmol)as a phase transfer reagent.Then,DT as a capping agent was added to the toluene phase at a2:1DT/Au ratio.An aqueous solution(25mL)of20mmol NaBH4as a reducing agent was slowly added(dropwise)to the solution.The reaction proceeded with stirring at ambient temperature for2h. Synthesized DT-Au nanoparticles were then puri?ed by multiple wash steps using ethanol.Nanoparticles were dried and dissolved in hexane.

The synthesis of silver nanoparticles with$3nm cores capped with decanethiolate monolayer shells(DT-Ag nanoparticles)followed a previously reported procedure [17–19].Brie?y,0.75mmol AgNO3was dissolved into a 25mL puri?ed water solution,which was added to a tolu-ene solution containing3.0mmol TOAB.DT was then added to this solution at a2:1DT/Ag ratio followed by the addition of an excess(20mmol)of NaBH4.Synthesized DT-Ag nanoparticles were puri?ed by multiple wash steps using ethanol.

The synthesis of DT-capped Au/Ag alloy(DT-Au/Ag) nanoparticles with$2nm cores were synthesized similar to the synthesis of gold and silver nanoparticles as described above[17–19].Mixed aqueous solutions with 90:10feed molar ratios HAuCl4to AgNO3were trans-ferred to a toluene solution containing 3.0mmol dmà3 TOAB.Excess DT was added to the solution.Excess NaBH4was slowly added to the solution as an aqueous reducing agent.The reaction proceeded with stirring at ambient temperature for2h.Synthesized DT-Au/Ag

38M.Tominaga et al./Journal of Electroanalytical Chemistry590(2006)37–46

nanoparticles were then puri?ed by multiple cleaning procedures.

Synthesized DT-Au,DT-Ag and DT-Au/Ag nanoparti-cles were characterized by X-ray photoelectron spectroscopy (XPS),UV–visible(UV–Vis)spectroscopy,transmission electron microscopy(TEM),and thermogravimetric analy-ses(TGA).

2.3.Preparation of carbon electrodes modi?ed with DT-Au, DT-Ag and DT-Au/Ag nanoparticles

DT-Au,DT-Ag and DT-Au/Ag nanoparticle-modi?ed electrodes were prepared as follows[24,25]:A plastic-formed carbon plate(PFC,Mitsubishi Pencil Co.,Japan, 2.5cm·2.5cm)was used as a substrate electrode.For the preparation of electrodes for cyclic voltammogram measurements,a50l L aliquot of DT-Au(5–10mg mlà1), DT-Ag(6–10mg mlà1)and DT-Au/Ag(8–12mg mlà1) nanoparticles in hexane was cast onto a PFC plate(surface area of ca.1cm2),and followed by natural evaporation at room temperature.For the preparation of electrodes for electrolysis,a200l L aliquot of nanoparticles was cast onto both sides of a PFC plate(surface area of ca. 13cm2).To remove the DT monolayer organic encapsulate from nanoparticles,PFC electrodes modi?ed with DT-Au, DT-Ag and DT-Au/Ag nanoparticles were heated from room temperature to300°C at a rate of10°C minà1, and the temperature was kept at300°C for2h under an air atmosphere using a mu?e furnace.The temperature was controlled to within±10°C.After heat-treatment, nanoparticles on electrodes were characterized by XPS, TG,IR,SEM and CV as described in the results and dis-cussion sections.

2.4.Analysis and characterization of nanoparticles

Synthesized nanoparticles were characterized using XPS,TEM,UV–Vis,TGA,IR,CV.TEM characterization was performed on a JEOL-2000FX electron microscope with an acceleration voltage of200kV.Nanoparticle sam-ples dissolved in hexane were cast onto a carbon-coated copper grid sample holder followed by natural evaporation at room temperature.

XPS measurements were carried out using a Thermo VG Scienti?c,Sigma Probe HA6000II.The instrument uses a focused monochromatic Al K a X-ray(1486.68eV)source for excitation and a spherical section analyzer,and a6-ele-ment multichannel detection system.The X-ray beam was incident normal to the sample and the detector was37°away from the normal.The percentage of individual ele-ments detected was determined from the relative composi-tion analysis of peak band areas.The Mo substrate was used for XPS analysis.

TGA was performed with a Seiko SSC5020thermal analysis system and a Seiko TG-300thermogravimetric analysis.Nanoparticle samples were cast onto an alumi-num sample pan(Seiko,in5mm diameter)and then evap-orated hexane.Samples weighing$5mg were heated at a rate of5°C minà1under an atmosphere.Aluminum oxide was used as a reference sample.

UV–Vis measurements were carried out with a Shima-dzu,UV-3100spectrophotometer.Spectra were collected over a range of300–800nm using a quartz cell with a 1cm path length.

FTIR re?ection spectra were obtained using a Bio-Rad FTS-6000spectrometer,which was purged with dry-nitro-gen gas.The spectrometer was equipped with a liquid nitrogen-cooled HgCdTe detector.Nanoparticles(hexane solution)were cast onto Si wafers and then evaporated hexane.IR spectra were collected over700–4000cmà1.

SEM images were observed to characterize surface mor-phology of nanoparticles modi?ed electrode using a JEOL JSM-6060L.For preparation of SEM sample,a10l L por-tion of nanoparticle(hexane solution)was cast on a PFC or high oriented pyrolytic graphite(HOPG)plate(ca.

0.32cm2).

2.5.Electrochemical measurement instrumentation

Cyclic voltammetric measurement and controlled-poten-tial electrolysis were performed with an electrochemical analyzer(ALS/Chi,Model600A)in a conventional three electrode cell with Ag/AgCl(saturated KCl)as the refer-ence electrode and a Pt plate as the counter electrode. For the electrolysis study,working and counter electrodes were separated by a glass?lter.All potentials were reported with respect to the Ag/AgCl(saturated KCl)electrode.The electrolyte solution was purged with high purity nitrogen before taking measurements.HPLC(PU-2080Plus, JASCO,Japan)combined with packed columns(Shodex KC-G+KC-811,Showa Denko,Japan)and a UV detector (UV-2075Plus,JASCO,at210nm)was employed to detect products generated by electrolysis.A phosphate solution (0.1%)was used as an eluent for HPLC.

3.Results and discussion

3.1.Characterization of nanoparticles

Before heat-treatment,surface content ratios(Au:Ag)of DT-Au/Ag nanoparticles were evaluated to be84:16by XPS.Fig.1shows TEM micrographs of DT-Au,DT-Ag and DT-Au/Ag nanoparticles and their population core sizes.The average core size of DT-Au,DT-Ag and DT-Au/Ag nanoparticles was evaluated to be2.3(±1.0),3.3 (±1.0)and2.0(±1.0)nm,respectively.Fig.2shows UV–Vis spectra of DT-Au,DT-Ag and DT-Au/Ag nanoparti-cles in hexane.Gold and silver nanoparticles are known to have surface plasmon(SP)resonance absorption bands in the visible region[26–28].DT-Au nanoparticles showed a weak SP resonance absorption at ca.520,which is in good agreement with that previously reported for similar particle sizes[10–13].For DT-Ag and DT-Au/Ag nanopar-ticles,SP resonance absorption were observed at ca.435

M.Tominaga et al./Journal of Electroanalytical Chemistry590(2006)37–4639

and 520nm,respectively.DT-Ag nanoparticles showed well-de?ned SP resonance peak,which might be due to core sizes larger than DT-Au and DT-Au/Ag.The wave-length and intensity of the SP resonance absorption are strongly dependent on alloy composition and particle core size [15,18,19].

3.2.Heat-treatment for nanoparticles

Fig.3shows representative of TGA data for DT-Au,DT-Ag and DT-Au/Ag nanoparticles.The mass decrease at ca.140°C and a transition at ca.210°C were observed.

Overall mass loss percentages were ca.22%,25%and 23%for DT-Au,DT-Ag and DT-Au/Ag nanoparticles,https://www.wendangku.net/doc/c517262460.html,pared to expected values of 21%for 2nm par-ticles,respectively,based on model calculations with the percentage of organic decanethiolate shells [11].Results obtained for DT-Au,DT-Ag and DT-Au/Ag nanoparticles were in good agreement with expected results.TGA data indicated that DT monolayer organic encapsulates were eliminated from nanoparticles by heat-treatment at 300°C for 2h under an air atmosphere as described in the experimental section.

On FT-IR re?ection spectra for DT-Au as shown in Fig.4a,before heat-treatment,bands corresponding to asymmetric and symmetric methylene stretching,v a,s (CH 2)(2921and 2852cm à1,respectively),and bands

corre-

Fig.1.TEM micrographs for DT-Au (a),DT-Ag (b)and DT-Au/Ag (c)nanoparticles,and the distribution of its core

size.

Fig. 2.UV–Vis spectra for DT-Au (a),DT-Ag (b)and DT-Au/Ag (c)nanoparticles in a

hexane.

Fig.3.TG analysis curves for DT-Au (a),DT-Ag (b)and DT-Au/Ag (c)nanoparticles.Samples were heated at a rate of 5°C min à1under an atmosphere.Aluminum oxide was used as a reference sample.

40M.Tominaga et al./Journal of Electroanalytical Chemistry 590(2006)37–46

sponding to asymmetric and symmetric methyl stretching,v a,s (CH 3)(2956and 2872cm à1,respectively),were observed [13,18,23,26,28].The Si wafer itself does not show any spectral change upon heat-treatment in this frequency region.Bands corresponding to diagnostic C–H bending,wagging and C–C stretching modes for DT-Au were also observed in the low-frequency region 1150–1400cm à1(not shown)[13,18,23,26,28].After heat-treatment,C–H alkyl chains representing absorption bands for DT in DT-Au nanoparticles in both the high-frequency region of 2800–3000cm à1and the low-frequency region of 1150–1400cm à1almost disappeared in the FT-IR re?ec-tion spectra (Fig.4b).These results clearly indicate that at least the DT alkyl chain for not only DT-Au but also DT-Ag and DT-Au/Ag nanoparticles had been removed.Surface species of DT-Au,DT-Ag and DT-Au/Ag nano-particles before and after heat-treatment were examined by XPS.Fig.5A(a)shows XPS data for DT-Au nanoparticles deposited on planer Mo substrates before heat-treatment,which shows peaks corresponding to S(2p)bands observed at 162.5and 163.5eV.The S(2p)band was characterized by a doublet arising from spin-orbit coupling,2p 3/2and 2p 1/2.The 2p 3/2peak arose $1eV lower compared to the

2p 1/2band because sulfur species interact strongly with the surface of gold [29,30].After heat-treatment at 300°C for 2h,the S(2p)band was no longer present at least below the detection limit.The oxidation of thiolate would produce the sulfonate species e–SO à3T,which shows a XPS peak around 167eV [31].After heat-treatment for DT-Au,almost no observation for peaks corresponding to sulfonate species were obtained.These XPS results together with results from TGA and FT-IR indicate that organic decanethiolate shells encapsulating DT-Au were completely removed from gold nanoparticles by heat-treatment at 300°C for 2h.

Results for DT-Au/Ag by heat-treatment were almost similar to those for DT-Au.Before heat-treatment,the doublet band corresponding to S(2p)of DT-Au/Ag was observed at 162.4and 163.6eV (Fig.5C(a)).After heat-treatment at 300°C for 2h,the S(2p)band was completely absent.Also,sulfonate species derived from oxidation of thiolate were not detected.These results indicate that decanethiolate shells from DT-Au/Ag were completely eliminated.Results obtained from TGA and FT-IR,as described above,also supported the complete elimination of decanethiolate shells from Au–Ag alloy nanoparticles.Fig.5B(a,b)shows XPS data for DT-Ag in the S(2p)region before and after heat-treatment.The obtained results after heat-treatment were di?erent from the results for DT-Au and DT-Au/Ag.Before heat-treatment the peak observed at 162.0eV was assigned to S(2p)of the thiolate species.After heat-treatment at 300°C for 2h,peaks corresponding to S(2p)were still observed at 162.0and 163.2eV.Both before and after heat-treatment,sulfur species derived from oxidation of thiolate were detected around 167eV [31].TGA and FT-IR results together with this result clearly indicate that the DT C–H alkyl chain for DT-Au/Ag was completely removed,however,the DT thiolate was still present.As described in the cyclic voltam-metric characterization,the thiolate could not be com-pletely eliminated by oxidation and reduction cycles of heat-treated Ag nanoparticles modi?ed electrodes in an alkaline aqueous

solution.

Fig.4.FT-IR spectra for DT-Au nanoparticles before (a)and after (b)the heat-treatment at 300°C for 2

h.

Fig.5.XPS spectra in the S(2p)region for DT-Au (A),DT-Ag (B)and DT-Au/Ag (C)nanoparticles before (A(a),B(a)and C(a),respectively)and after heat-treatment at 300°C for 2h (A(b),B(b)and C(b),respectively),and for heat-treated DT-Ag nanoparticles followed by three cycles of oxidation and reduction in a region of à0.8$0.8V in a 0.1mol dm à3NaOH solution (B(c)).

M.Tominaga et al./Journal of Electroanalytical Chemistry 590(2006)37–4641

Furthermore,it was noted that surface content ratios (Au:Ag)for DT-Au/Ag nanoparticles changed before and after heat-treatment at300°C for2h.Before heat-treatment surface content ratios(Au:Ag)were evaluated to be84:16by XPS,as described above.However,after heat-treatment surface content ratios were evaluated to be73:27,indicating that the surface content ratio of Ag increased after heat-treatment.A similar tendency was also observed at Au–Ag alloy nanoparticles with various content ratios.For example,Au–Ag nanoparticles with surface content ratios Au:Ag(91:9)and Au:Ag(54:46) changed to Au:Ag(83:17)and Au:Ag(35:65)by heat-treat-ment at250°C for30min.XPS probes had relatively more surface composition than the composition in layers under the surface.These results would indicate that sur-faces of Au–Ag alloy nanoparticles prepared herein are enriched with Ag atoms compared with the inner parts of alloy nanoparticles.

Fig.6A shows cyclic voltammograms at PFC electrodes modi?ed with Au,Ag and Au/Ag nanoparticles in a 0.1mol dmà3H2SO4solution,where nanoparticles modi-?ed PFC electrodes were prepared by heat-treatment at 300°C for2h.Typical redox responses corresponding to the oxidation and reduction of Au were observed at Au nanoparticles modi?ed electrodes at a potential range of 0.6–1.5V,as shown in Fig.6A(a).This voltammetric behavior was similar to a polycrystalline Au electrode. For Ag nanoparticles modi?ed electrodes(Fig.6A(b)),oxi-dation and reduction responses for Ag nanoparticles were obtained at0–https://www.wendangku.net/doc/c517262460.html,rge oxidation and reduction peaks of Ag nanoparticles were observed around0.7and0.3V, respectively.Fig.6A(c)shows the cyclic voltammogram at Au/Ag nanoparticles modi?ed electrodes.It is interest-ing to note that the voltammogram shape was very similar to the Au nanoparticle modi?ed electrode,and there was no redox peak representing an Ag surface even when nano-particles contained27%Ag atoms on their surface.This result provides strong evidence that Au–Ag alloy nanopar-ticles are composed by atomically mixed Ag and Au atoms, not composed by Ag and Au metal domains.In a 0.1mol dmà3NaOH solution,redox waves of Au/Ag nanoparticles modi?ed electrodes were similar to those of Au nanoparticles modi?ed electrodes(Fig.6B),which also supports the distribution of Au and Ag atoms of Au/Ag nanoparticles on nanocrystal surfaces as being relatively homogeneous.

It is known that the electrochemical oxidative desorp-tion of self-assembled alkanethiolate monolayers on planar gold surfaces occurs in alkaline solutions[32].By three cycles of oxidation and reduction in a region of à0.8$0.8V at heat-treated Ag nanoparticles modi?ed electrodes in a0.1mol dmà3NaOH solution,the signi?-cant decrease of XPS peaks for the remaining thiolate spe-cies on nanoparticles was observed as shown in Fig.5B(c). Therefore,prior to using Ag nanoparticle modi?ed elec-trodes for electrochemical measurements,the electrodes were carried through three cycles of oxidation and reduc-tion in an alkaline solution.

Fig.7shows typical surface morphology for a bare PFC surface and DT-Au nanoparticles modi?ed PFC electrode before and after heat-treatment at300°C for2h.The sur-face morphological change in the Au nanoparticle?lm on PFC was observed after heat-treatment.To investigate nanometer scale size,TEM measurements were

carried

out.The TEM image was obtained after heat-treatment at 300°C for 2h for DT-Au nanoparticles cast on a carbon-coated grid sample holder.The results of TEM image indicated that Au nanoparticles aggregated,however nano-particles retained their shapes.The similar results were obtained,when DT-Ag and DT-Au/Ag nanoparticles were used.When a HOPG substrate was used,surface morpho-logical changes induced by heat-treatment were almost the same as results obtained using PFC.

3.3.Voltammetric studies on the electrocatalytic oxidation of glucose

Before heat-treatment,no electrocatalytic oxidation of glucose was observed at PFC electrodes modi?ed with Au,Ag and Au/Ag nanoparticles.This behavior can be understood to mean that organic DT shells of nanoparti-cles block the reaction of glucose at the metal surface of nanoparticles.

Fig.8a–c shows a typical voltammetric curve at PFC electrodes modi?ed with Au,Ag and Au/Ag nanoparticles in a 0.1mol dm à3NaOH aqueous solution in the presence of 5mmol dm à3glucose.The electrocatalytic oxidation of glucose at PFC electrodes was not observed over a poten-tial range of à0.8to 0.8V.At PFC electrodes modi?ed with Au nanoparticles (Fig.8a),two large oxidation peaks of interest were observed around à0.4and 0.4V,which correspond to the oxidation of glucose and the further oxi-dation of gluconolactone (as shown in Fig.8d)generated by the ?rst oxidation peak (ca.à0.4V),respectively [2,3,5].For Au/Ag nanoparticles modi?ed electrodes,two major oxidation peaks were also observed around à0.4and 0.6V (Fig.8c),which correspond to the oxidation of glucose and the further oxidation of

gluconolactone

Fig.7.Typical SEM images for a PFC substrate surface (a)and DT-Au nanoparticle-modi?ed PFC surfaces before (b)and after (c)heat-treatment at 300°C for 2

h.

Fig.8.Typical voltammetric curves at Au,Ag and Au/Ag nanoparticle modi?ed electrodes in a 0.1mol dm à3NaOH solution in the presence of 5mmol dm à3glucose (a,b and c,respectively)and gluconolactone (d,e and f,respectively),and in the absence of glucose and gluconolactone (broken line).Potential sweep rate:50mV s à1.Electrode area:0.26cm 2.

M.Tominaga et al./Journal of Electroanalytical Chemistry 590(2006)37–4643

(Fig.8f).It is interesting to note that the catalytic current at Au/Ag nanoparticle modi?ed electrodes were observed from ca.à0.75V,which represent a negative potential shift of ca.0.1V compared to that at Au nanoparticle modi?ed electrodes.This result indicates that Au–Ag alloy nanopar-ticles are e?ective catalysts for the electrocatalytic oxida-tion of glucose.This observed e?ect of silver on the electrocatalytic oxidation of glucose was in good agree-ment with previous investigations using single crystal gold modi?ed with silver by under-potential deposition[5,6].

Aldose-type monosaccharides such as mannose,galac-tose and xylose showed well-de?ned catalytic oxidation peaks aroundà0.4and0.4$0.6V at the Au and Au/Ag nanoparticles modi?ed electrodes in a0.1mol dmà3NaOH aqueous solution similar to the same aldose-type monosac-charide,glucose.While ketose-type monosaccharides such as fructose and sorbose did not show any catalytic oxida-tion peak in the potential region ofà0.8$0.8at Au and Au/Ag nanoparticle modi?ed electrodes.

At Ag nanoparticle modi?ed electrodes,typical voltam-metric curves displayed an oxidation wave at ca.0.35V extending to the potential limit in the absence of glucose. This oxidation peak is attributed to the oxidation of silver(0)to silver(I)[33].In the presence of glucose,the catalytic oxidation current was observed at ca.0.5V, which peak potential was$0.15V positive compared to that in the absence of glucose(Fig.8b).The result obtained was similar to the behavior observed at silver electrodes[33].These results indicate that glucose was oxi-dized catalytically at Ag nanoparticles.Although,a linear relationship between the oxidation peak current did not increase with glucose concentration.Further investigation is under way.

3.4.Controlled-potential electrolysis of glucose

As previously reported,we have already noted advanta-ges in using nanoparticles for the controlled-potential elec-trolysis of glucose[24,25].In this study,Au,Ag and Au/Ag nanoparticles modi?ed electrodes in a0.1mol dmà3NaOH solution,experienced current decreases was also much slower than that at gold plate electrodes.Therefore,a suf-?cient current?ow to detect electrolysis products was per-formed at Au,Ag and Au/Ag nanoparticles.

The controlled-potential electrolysis of glucose was per-formed in a0.1mol dmà3NaOH solution containing 10mmol dmà3glucose at potentials atà0.3and0.3V using PFC electrodes modi?ed with Au,Ag and Au/Ag nanoparticles.Table1shows a summary of controlled-potential electrolysis results.After electrolysis at a poten-tial ofà0.3V using Au nanoparticle modi?ed electrodes, gluconolactone(or gluconate)was only detected by HPLC at a current e?ciency of100%,which results in good agree-ment with previous papers[24,25].At Au/Ag nanoparticle modi?ed electrodes,gluconolactone was also detected at a current e?ciency of100%after electrolysis atà0.3V. These electrolysis results for Au and Au/Ag nanoparticles indicate that a two-electron oxidation for glucose occurred at nanoparticles-modi?ed electrodes atà0.3V[2,4,5].

At electrolysis potential of0.3V,a strong metal compo-sition dependence of nanoparticles on electrolysis oxida-tion products was obtained.For Au nanoparticle modi?ed electrodes,oxalate(18-electron oxidation prod-uct)and gluconolactone(or gluconate)were detected as main products,indicating that the electrocatalytic oxida-tion was promoted at more positive electrolysis potentials compared to the electrolysis atà0.3V.For Au/Ag nano-particles modi?ed electrodes,formate(12-electron oxida-tion product)was detected as an electrolysis product in addition to oxalate and gluconolactone as main products. The remarkable di?erence between Au and Au/Ag nano-particles modi?ed electrodes was evident on electrolysis products.First,the current e?ciency for gluconolactone at Au/Ag nanoparticles was much smaller than that at Au nanoparticles.Secondly,formate,a12-electron oxida-tion product,was one of the main products at Au/Ag nanoparticle modi?ed electrodes,whereas formate was not detected at Au nanoparticles.This result would indi-cate that the formation of surface oxygenated species plays an important role in catalytic selectivity.Thirdly,it is inter-esting to note that the current e?ciency for electrolysis products at Au/Ag nanoparticles modi?ed electrodes was similar to that at Ag nanoparticle modi?ed electrodes. These results indicate that catalytic selectivity at potential

Table1

Results from the controlled-potential electrolysis of glucose

Electrolysis potential (E/V vs.Ag/AgCl)Electrodes Current e?ciencies(%)Charge

?ow(C) Oxalate18e-Formate12e-Glycolate6e-Glucarate6e-Gluconolactones2e-Total

à0.3Au nano––––ca.100ca.10020 Au/Ag––––ca.100ca.10015

0.3Au nano2242205510330

Ag nano run124538–1110320

Ag nano run226454–311025

Au/Ag run119557–179820

Au/Ag run130498–1610220

The controlled-potential electrolysis was performed at PFC electrodes modi?ed with Au,Ag and Au/Ag nanoparticles in a0.1mol dmà3NaOH solution (20ml)in the presence of10m mol dmà3glucose atà0.3and0.3V.Electrode area:ca.10cm2.

44M.Tominaga et al./Journal of Electroanalytical Chemistry590(2006)37–46

of0.3V would be governed by ca.30%silver atoms con-taining Au/Ag nanoparticles surfaces even if the other ca. 70%gold atoms are contained,and Au/Ag nanoparticles shows electrolysis results similar to Ag nanoparticles.

4.Conclusions

In conclusion,Au,Ag and Au–Ag alloy nanoparticles capped with decanethiolate monolayer shells(DT-Au, DT-Ag and DT-Au/Ag)were synthesized by a two-phase synthesis protocol.Average core sizes for DT-Au,DT-Ag and DT-Au/Ag were evaluated by TEM to be2.3(±1.0), 3.3(±1.0)and2.0(±1.0)nm,respectively.Heat-treatments were performed at300°C for2h to remove DT organic shells from nanoparticles.Results from TGA,FT-IR and XPS clearly indicated that C–H alkyl chains and thiolates from DT caps on Au and Au/Ag nanoparticles were com-pletely eliminated after heat-treatment.In DT-Ag nanopar-ticles,elimination of DT C–H chains by heat-treatment was evident by TGA and FT-IR results,however XPS results indicated that DT thiolates were still present on Ag nano-particle surfaces.Eventually,the remaining thiolate on Ag nanoparticles was almost removed by oxidation and reduc-tion cycles in an alkaline solution.The surface content ratio of Au and Ag was evaluated to be Au:Ag(84:16)by XPS measurements before heat-treatment.After heat-treatment at300°C for2h,the surface content ratio changed to Au:Ag(73:27).The increasing surface content ratio of Ag after heat-treatment was also observed with other content ratios of Au–Ag alloy nanoparticles.Results in cyclic vol-tammograms at Au/Ag nanoparticles modi?ed PFC elec-trodes in H2SO4and NaOH solutions were similar to those at Au nanoparticle modi?ed electrodes,unlike those at Ag nanoparticle modi?ed electrodes,which indicate the distribution of Au and Ag atoms of Au/Ag nanoparticles on nanocrystal surfaces is homogeneous.

Using heat-treated activated nanoparticles,the electro-catalytic oxidation of glucose was examined in a NaOH solution.Catalytic oxidation peaks for glucose around à0.4and0.4V at Au nanoparticle modi?ed electrodes and aroundà0.4and0.6V at Au/Ag nanoparticles modi-?ed electrodes were observed,which correspond to the oxi-dation of glucose and the further oxidation of gluconolactone generated by the?rst oxidation peak (à0.4V),respectively.It is interesting to note that the cat-alytic current at Au/Ag nanoparticles modi?ed electrodes was observed from ca.à0.75V,which represents a nega-tive potential shift of ca.0.1V compared to that at Au nanoparticle modi?ed electrodes.This result indicates that Au–Ag alloy nanoparticles are e?ective catalysts for the electrocatalytic oxidation of glucose.At both Au and Au/Ag nanoparticles,aldose-type monosaccharides showed catalytic oxidation peaks in an alkaline solution, however ketose-type monosaccharides did not show any catalytic peaks in the potential region ofà0.8$0.8V.

The controlled-potential electrolysis of glucose was per-formed in a0.1mol dmà3NaOH solution.After electroly-sis at a potential ofà0.3V,gluconolactone(or gluconate, two-electron oxidation product)was only detected at a cur-rent e?ciency of100%at Au and Au/Ag nanoparticle modi?ed electrodes.In the case of0.3V,oxalate(18-elec-tron oxidation product)and gluconolactone were detected as the main product at Au nanoparticle modi?ed elec-trodes.For Au/Ag nanoparticle modi?ed electrodes,for-mate(12-electron oxidation product)was detected in addition to oxalate and gluconolactone as main products, which is a similar result with Ag nanoparticle modi?ed electrodes.These results would indicate that the catalytic selectivity at a potential of0.3V is governed by ca.30%sil-ver atoms containing Au/Ag nanoparticles surfaces.XPS measurements were carried out to recon?rm the surface metal composition ratio after electrolysis.The content ratio of Au:Ag(73:27)was observed,which was exactly the same surface metal composition ratio before electrolysis.Further investigations into the e?ect of content ratios of Au and Ag on electrolysis products are under way to gain insight into catalytic selectivity.

Acknowledgement

This work was supported in part by a Grant-in-Aid for Scienti?c Research(M.T.)from the Ministry of Education, Culture,Science,Sports and Technology,Japan. References

[1]Y.B.Vassilyev,O.A.Khazova,N.N.Nikolaeva,J.Electroanal.

Chem.196(1985)127.

[2]https://www.wendangku.net/doc/c517262460.html,rew,D.C.Johnson,J.Electroanal.Chem.262(1989)167.

[3]R.R.Adzic,M.W.Hsiao,E.B.Yeager,J.Electroanal.Chem.260

(1989)475.

[4]M.W.Hsiao,R.R.Adzic,E.B.Yeager,J.Electrochem.Soc.143

(1996)759.

[5]S.Ben Aoun,Z.Dursun,T.Koga,G.S.Bang,T.Sotomura,I.

Taniguchi,J.Electroanal.Chem.567(2004)175.

[6]S.Ben Aoun,G.S.Bang,T.Koga,Y.Nonaka,T.Sotomura,I.

Taniguchi,https://www.wendangku.net/doc/c517262460.html,mun.5(2003)317.

[7]M.Haruta,Chem.Rec.3(2003)75.

[8]A.Wieckowski,E.R.Savinova,C.G.Vayenas(Eds.),Catalysis and

Electrocatalysis at Nanoparticle Surfaces,Marcel Dekker,New York, 2003.

[9]B.Zhou,S.Hermans,G.A.Somorjai(Eds.),Nanotechnology in

Catalysis,Kluwer Academic/Plenum,New York,2004.

[10]M.M.Maye,J.Luo,L.Han,N.N.Kariuki,C.J.Zhong,Gold Bull.

36(2003)75.

[11]M.Brust,M.Walker,D.Bethell,D.J.Schi?rin,R.Whyman,J.

Chem.Soc.,https://www.wendangku.net/doc/c517262460.html,mun.(1994)801.

[12]M.J.Hostetler,J.E.Wingate,C.J.Zhong,J.E.Harris,R.W.Vachet,

M.R.Clark,J.D.Londono,S.J.Green,J.J.Stokes,G.D.Wignall,

G.L.Glish,M.D.Porter,N.D.Evans,R.W.Murray,Langmuir14

(1998)17.

[13]M.M.Maye,W.Zheng, F.L.Leibowitz,N.K.Ly, C.J.Zhong,

Langmuir16(2000)490.

[14]A.C.Templeton,W.P.Wuel?ng,R.W.Murray,Acc.Chem.Res.33

(2000)27.

[15]M.M.Maye,L.Han,N.N.Kariuki,N.K.Ly,W.-B.Chan,J.Luo,

C.J.Zhong,Anal.Chim.Acta496(2003)17.

[16]J.Luo,V.W.Jones,M.M.Maye,L.Han,N.N.Kariuki,C.J.Zhong,

J.Am.Chem.Soc.124(2002)13988.

M.Tominaga et al./Journal of Electroanalytical Chemistry590(2006)37–4645

[17]M.J.Hostetler,C.J.Zhong,B.K.H.Yen,J.Anderegg,S.M.Gross,

N.D.Evans,M.D.Porter,R.W.Murray,J.Am.Chem.Soc.120 (1998)9396.

[18]S.W.Han,Y.Kim,K.Kim,J.Colloid Interf.Sci.208(1998)272.

[19]N.N.Kariuki,J.Luo,M.M.Maye,S.A.Hassan,T.Menard,H.R.

Naslund,Y.Lin,C.Wang,M.H.Engelhard,C.J.Zhong,Langmuir 20(2004)11240.

[20]Y.Lou,M.M.Maye,L.Han,J.Luo,C.J.Zhong,https://www.wendangku.net/doc/c517262460.html,mun.

473(2001).

[21]J.Luo,M.M.Maye,Y.Lou,L.Han,M.Hepel,C.J.Zhong,Catal.

Today77(2002)127.

[22]J.Luo,M.M.Maye,N.N.Kariuki,L.Wang,P.Njoki,Y.Lin,

M.Schadt,H.R.Naslund, C.J.Zhong,Catal.Today99(2005) 291.

[23]M.J.Hostetler,J.J.Stokes,R.W.Murray,Langmuir12(1996)

3604.[24]M.Tominaga,T.Shimazoe,M.Nagashima,I.Taniguchi,Electro-

https://www.wendangku.net/doc/c517262460.html,mun.7(2005)189.

[25]M.Tominaga,T.Shimazoe,M.Nagashima,I.Taniguchi,Chem.

Lett.34(2005)202.

[26]S.Y.Kang,K.Kim,Langmuir14(1998)226.

[27]P.Mulvaney,Langmuir12(1996)788.

[28]S.R.Johnson,S.D.Evans,S.W.Mahom,A.Ulman,Langmuir13

(1997)51.

[29]C.J.Zhong,R.C.Brush,J.Anderegg,M.D.Porter,Langmuir15

(1999)518.

[30]M.C.Bourg,A.Baida,R.B.Lennox,J.Phys.Chem.B104(2000)

6562.

[31]D.A.Hutt,G.J.Leggett,J.Phys.Chem.100(1996)6657.

[32]C.A.Widrig,C.Chung,M.D.Porter,J.Electroanal.Chem.310

(1991)335.

[33]J.M.DeMott,E.G.E.Jahngen,Electroanalysis17(2005)599.

46M.Tominaga et al./Journal of Electroanalytical Chemistry590(2006)37–46

西安1天行程各峪口路书

希望大家补充、修正。 【以下里程均为到秦岭各峪口的往返距离】 一水陆庵悟真寺 100 公里。霸陵乡--东李村过灞河--华胥--蓝田--312国道。 二岱峪约100公里。雁引路--环山路--将军岭收费站--小寨--岱峪口。 二1 上湖滩 110. 雁引路(或走半引路)--环山路--焦岱--牛心峪--上湖滩。 二2 大洋峪 110. 雁引路(或半引路)--环山路--焦岱--吴家寨--大洋峪。 三汤峪 90 雁引路--环山路--向东--汤峪路口南拐。或走鸣犊--魏寨82公里。 四骆驼岭 80 同上到孙家沟水库。 五库峪 80 雁引路--环山路--杨庄--库峪口。可到太兴山公园门口,或爬太兴山。若走引镇近些。 薰衣草庄园在杨庄和库峪口之间 六扯袍峪 76 雁引路--引镇--浦江村东拐--穿过环山路--许家沟水库、东沟水库。(或引镇到 杨庄路,过环山路后沿右手水泥路直走进山),爬人头山。 七大峪 70 雁引路--大峪口。可骑车进山 1 爬莲花洞,需天长。 2 西翠花。 3 进鲜峪沟。 4 上嘉午台,需天长。一是从五里庙上;另也可从十里铺过 小桥经左转沟、狮子茅棚、老龙头上。 八白道峪 72 雁引路--环山路口向西南拐。 1 经冷水泉、大峪间的分水岭、嘉午台。 九小峪 70 韦曲--杜曲--王莽--清水头。 1 进寨沟,可近可远。 2 寺沟到轩辕庙。 3 车放柳金坪,溯小峪河而上,可近可远。沟内可骑行。 十洋峪 70 韦曲--王莽--清水头--郑家坡。沟内无人水不大。 十一土门峪 72 韦曲--杜曲--太乙宫向东--土门村。或环山路太乙宫路口向东再向南。可到二龙塔,天池寺。

十二蛟峪 70 韦曲--杜曲--太乙宫向东。 1 二龙塔---天池寺。 2 车放水库旁,经天池寺沿 山梁朝东南向,可到大片芦苇地。 3 二郎山 4 进蛟峪沟朝里走,沟窄路陡。 十三太峪 70 韦曲--杜曲--太乙宫。 1 经西岔沟上南五台 2 翠华山。沟内可骑行。 十四康峪沟 70 韦曲--王曲--环山路向东2公里南拐--新农村。到青莲寺或更远。可能封山。 十五东西胡清沟 70 韦曲--王曲--五台镇向东南拐。沟不深可穿越两沟。 十五1 白蛇峪 70 南五台大门直往南走就是。 十六南五台沟 70 韦曲--王曲--五台镇--沟口向西。 1 送登台 2 圣寿寺看北魏方塔 3刘澜涛别墅 4 登南五台,需天长。水泥路可骑到刘澜涛别墅。 十七石砭峪 70 韦曲--王曲--环山路向西一公里南拐 1 熊沟,天长时由此上南五台。 2 大瓢沟 3小瓢沟 4青岔可骑行至青岔或罗汉坪,冉家坪。 十八天子峪 70 子午大道--环山路向东经百塔寺。 1 东天子峪,可骑车上。 2 西天子峪 骑车到至相寺 3 沿沟往里走可长可短,最远可到唐王寨。 十九抱龙峪 70 子午大道--五台镇--抱石村。 1上唐王寨。 2 看瀑布,冬天看冰瀑。可骑车。 廿小五台沟 70 子午大道--南豆角。上小五台。往南为五道梁。 廿一子午峪 68 子午大道 --过环山路向南。 1 果峪沟上山梁 2 到小五台3 从小五台 沿山脊向南五道梁,。 4 可推车至土地梁,或往前经枣儿岭穿越至210国道返回。 廿二鸭峪 68 子午大道--南豆角向西南。可山梁到果峪沟,或向西沿山梁穿越白石峪。 廿三白石峪 70 子午大道或西沣路到内苑村(野生动物园后。可到孤独原。

医用高分子常用材料(精)

医用高分子常用材料 学校名称:华南农业大学 院系名称:材料与能源学院 时间:2017年2月27日

3.结构与性能 3.3 常用材料 1.硅橡胶 硅橡胶是一种以Si-O-Si为主链的直链状高分子量的聚有机硅氧烷为基础,添加某些特定组分,按照一定的工艺要求加工后,制成具有一定强度和伸长率的橡胶态弹性体。 硅橡胶具有良好的生物相容性、血液相容性及组织相容性,植入体内无毒副反应,易于成型加工、适于做成各种形状的管、片、制品,是目前医用高分子材料中应用最广、能基本满足不同使用要求的一类主要材料。 具体应用有:静脉插管、透析管、导尿管、胸腔引流管、输血、输液管以及主要的医疗整容整形材料。 2.聚乳酸 聚乳酸是以乳酸或丙交酯为单体化学合成的一类聚合物,属于生物降解的热塑性聚酯,具有无毒、无刺激、良好的生物相容性、可生物分解吸收、强度高、可塑性加工成型的合成类生物降解高分子材料。 其降解产物是乳酸、CO2和H2O。经FDA批准可用作手术缝合线、注射用微胶囊、微球及埋置剂等制药的材料。u=3351883538,102612699&fm=21&gp=0 3.聚氨酯 聚氨酯是指高分子主链上含有氨基甲酸酯基团的聚合物,简称PU,是由异氰酸酯和羟基或氨基化合物通过逐步聚合反应制成的,其分子链由软段和硬段组成。聚氨酯具有一个主要的物理结构特征是微相分离结构,其微相分离表面结构与生物膜相似。 由于存在着不同表面自由能分布状态,改进了材料对血清蛋白的吸附力,抑

制血小板黏附,具有良好的生物相容性和血液相容性。目前医用聚氨酯被用于人工心脏、心血导管、血管涂层、人工瓣膜等领域。 参考文献 [1] 李小静,张东慧,张瑾,等.医用高分子材料应用五大新趋势[J].CPRJ中国塑料橡胶,2016 [2]杂志社学术部,医用高分子材料的临床应用:现状和发展趋势.中国组织工程研究与临床康复,2010,14(8)

高分子材料论文

高 分 子 材 料 论 文 课题名称:高分子材料导论学院: 班级: 姓名: 学号:

高分子材料回收利用与发展可降解材料现代文明以经济腾飞和生活水平的提高为主要标志。随着经济发展,大规模的物质循环不可避免地引起各种问题,如资源短缺、环境恶化已为全球所关注。科学家预言地球能源(煤、石油、天然气等)不久将消耗完,会发生严重的能源危机;现代工业以及消费业的发展已给大自然带来严重的影响,大气、海洋等受污染,温室效应发生和臭氧层的破坏等等。所有这些已严重影响着自然界的生态平衡,最终必然会阻碍世界经济的高速发展。 材料的制造、加工、应用等均与环境和资源有直接的关系。高分子材料自从上世纪初问世以来,因重量轻、加工方便、产品美观实用等特点,颇受人们欢迎,其应用越来越广,从而使用过的高分子材料日益增加。据统计,2011年,我国塑料制品的产量达5474万吨,同比增长22%。其中,塑料薄膜的产量为844万吨,占总产量的15%;日用塑料制品的产量为458万吨,占总产量的8%;塑料人造革、合成革的产量为240万吨,占总产量的4%。如何处理这些废料已成为非常重要的课题。 处理废旧高分子材料比较科学的方法是再循环利用。循环是废旧高分子材抖利用的有利途径,不仅使环境污染得到妥善的解决,而且资源得到最有效的节省和利用。从资源利用的角度,对废旧高分子材料的利用首先应考虑材料的循环,然后考虑化学循环及能量回收。 回收:我国塑料回收面临的困难是数量大、分布广、品种多、体积大,许多废塑料与其它城市垃圾混在一起。处理废塑料的主要方法是:填埋和简单焚烧,但可供填埋场地不断减少,填埋费用急剧上升以及简单焚烧带来的二次污染等问题也给我们敲响了警钟。国外在废塑料回收方面已积累了不少经验,他们把废塑料的回收作为一项系统工程,政府、企业、居民共同参与。德国于1993年开始实施包装容器回收再利用,1997年回收再利用废塑料达到60万t,是当年消费量(80万t)的75%。目前,德国在全国设立300多个包装容器回收、分类网点,各网点统一将塑料制品分为瓶、薄膜、杯、PS发泡制品及其他制品,并有统一颜色标志[2]。利用:主要有再生利用、热能利用以及分解产物的利用(包括热分解和化学分解)。 1、再生利用:再生利用分简单再生和改性再生两类。 简单再生,指废塑料经过分类、清洗、破碎、造粒后直接进行成型加工,一般只能制成档次较低的产品。 改性再生,指通过化学或机械方法对废塑料进行改性。改性后的再生制品力学性能得到改善,可以做档次较高的制品。在化学添加剂方面,汽巴-嘉基公司生产出一种含抗氧剂、共稳定剂和其他活性、非活性添加剂的混合助剂,可使回收材料性能基本恢复到原有水平;荷兰有人开发了一种新型化学增容剂,能将包含不同聚合物的回收塑料键合在一起。美国报道采用固体剪切粉碎工艺(Solid State Shear Pulverization, S3P)进行机械加工,无须加热和熔融便可将树脂进行分子水平剪切,形成互容的共混物。共混物大部分由HDPE和LLDPE组成,极限拉伸强度和挠曲模量可与HDPE和LLDPE纯料相媲美[5]。 2、焚烧回收热能: 对于难以进行清洗分选回收的混杂废塑料,可以在专门的焚烧炉中焚烧以回收热能。木材的燃烧热为14.65 GJ/kg,聚乙烯为46.63 GJ/kg,聚丙烯为43.95 GJ/kg,聚氯乙烯为18.08 GJ/kg,ABS为35.26 GJ/kg,均高于木材,若能将这部分热能加以回收是很有意义的。废塑料热能回收可最大限度减少对自然环境的污染,不需要繁杂的预处理,也不需与生活垃圾分离,焚烧后废塑料的质量和体积可分别减少80%和90%以上,燃烧后的渣滓密度较大,

西安鲜衣怒马再千年

龙源期刊网 https://www.wendangku.net/doc/c517262460.html, 西安鲜衣怒马再千年 作者: 来源:《科学大观园》2018年第11期 西安是古老还是鲜活?它究竟是一个怎样的城市? 它历经无数次城毁人失,却总有一种力量让它焕然一新,让它鲜衣怒马。 每个人心中都有一个西安,或是秦皇的兵马俑,或是汉唐的长安城,又或是明清的古城墙。这个位于中国腹地的城市,王朝更迭无数、古迹遗留遍地,它们共同赋予西安一个深刻的标签:古老。然而今天的西安,标签似乎截然相反:鲜活。它发动“抢人”大战,3个月落户人数高达21万,直逼2017年全年总量;它关注温情的小事,要求所有机动车在斑马线前礼让行人。另一方面,一批又一批的网友赶往西安,喝着豪气干云的摔碗酒,吃着书卷气十足的毛笔酥,传统西安美食的创新能力也令人刮目相看。 西安初生 西安,它不是纯粹的平原,而是一半山地,一半平原。山在平原前巍峨耸立,平原在山脚下缓缓铺陈。 千百万年前,今天秦岭北部的地层发生断裂,断层北部持续下陷,断陷形成关中盆地,南部则不断隆升崛起成为秦岭山脉。太白山、翠华山、终南山、骊山、华山,从西向东连绵展布,高山、云海波澜壮阔,蔚为大观,山地中发育出大量水系,水系切穿山体形成峡谷,秦岭面向关中盆地的一侧,诸多峡谷依次并排而立,如同群龙吐水,是为秦岭七十二峪。流水冲出大小峪口,流向关中盆地,盆地内湖沼遍布、河流纵横,沣河、涝河、潏河、滈河、浐河、灞河等,再加上北部的泾河共同注入渭河,统称为长安八水。这些河流、湖沼带来大量的泥沙经过漫长的沉积,关中盆地的沉积物厚达千米,号称“八百里秦川”的关中平原诞生了。西安人的舞台将在这片肥沃的土地上展开。 鲜衣怒马 约6000年前,早期的一批“西安人”居住在浐河、泾河等河流的岸边。他们有着近似现代南方人的相貌,成年男性的平均身高可以达到170cm,他们所使用的器具简单而朴素,他们 是渔民、猎手、野果采集者,对鱼有着神秘的崇拜。他们生产力低下,备受疾病、野兽、部落敌人的威胁,儿童夭折的悲剧频繁发生,成年人的寿命也只有30~40岁,对生命的祈祷凝固为一个人面鱼纹符号刻画在陶盆之中。 3000多年前,擅长农耕以农民为主的周人,从甘肃、陕西黄土高原出发加入“西安市民”的行列。周人带来了先进的生产技术和精细化的农田管理,他们为作物除草、施肥,甚至利用雨

药用高分子材料及其相关发展

药用高分子材料及其相关发展 李彦松 制药072 学号:050714214 摘要随着材料科学的高速发展,高分子材料对药物制剂的研究和发展也起到非常重要的作用。本文将着重介绍药用高分子材料与药物制剂的发展;药用高分子材料的安全性;我国药用高分子应用和研究开发现状;高分子辅料与缓控释系统发展的关系。 关键词药用高分子材料、生物相容性、辅料、高分子辅料、缓控释系统 药用高分子材料学是高分子科学与生命科学等诸学科之间互相渗透的一个重要交叉领域。药用高分子材料在现代药物制剂的研发、生产和应用中起着重要的作用,对开发提高药品质量和发展新型药物传输系统具有重要的意义。 1.药用高分子材料与药物制剂的发展 药用高分子材料是指在药物制剂中应用、本身一般不具备药理和生理活性但能够赋予或改善药物制剂特定性能的各种高分子。药用高分子材料在现代药物制剂研发及生产中起着重要作用,对提高药品质量和发展新型药物传输系统具有重要意义[1]。表1列出了目前在药物制剂中常用的一部分药用高分子材料。可以看出,作为药剂添加剂应用的高分子多种多样,它们可以是药品成形的助剂,也可以用于提高药物稳定性、溶解性、吸收和生物利用度等[2]。 表1 药物制剂常用的高分子材料

正因为许多新的具有特殊性能的高分子材料的出现,诸如口服缓释和控释片剂、微丸剂、皮下埋植剂以及注射用靶向制剂等现代药物传输系统等才得以问世。这些新型药物制剂改变了人们的用药方式和给药量,使疾病的治疗和预防更为有效[4]。采用纤维素衍生物和丙烯酸树脂制备的不同药物的缓释及控释片剂和胶囊己经在临 床治疗中广泛使用,一天需数次服药的许多普通制剂正在被一天二次或仅服一次的缓控释制剂取代,在减少服药次数的同时降低了血药浓度的波动性、减少了毒副作用而受到患者的欢迎。原来需要每日注射一次的促黄体激素释放激素注射液,在制备成聚乳酸微球后一次皮下注射可将药效延长至3个月甚至6个月之久。应用高分子材料作为多肤、蛋白质以及基因的转运载体已成为21世纪初的热点研究领域。 2.药用高分子材料的安全性 药用高分子材料不仅需要强调其功能性而且必须强调其安全性,未经严格安全性研究和批准的新材料不能作为药物制剂添加剂使用[5]。国际药用辅料协会(Interna- Tional Pharmaceutical Excipients Council, IPEC)于1997年提出了较为详细的对新辅料安全性评价的指南。 生物相容性(Biocompatibility)评价是对药用高分子材料的重要内容。包括材料与机体组织或血液长期接触时产生的生物学反应性,也包括这些外来物质在机体因素影响下产生的自身功能的、物理的和化学的变化。各种用于皮下、肌肉等组织的埋植剂、器官、关节腔、血管注射的药用高分子材料微粒等须特别重视其生物相容性问题。材料与组织相接触后性能变化与否称为组织相容性(tissue compatibility)。例如,生物相容性不佳的高分子材料埋植剂有可能在肌肉产生刺激性、炎症、肉芽肿、坏死等生理不良反应,也可能因肌肉组织细胞的粘附、体液成分的作用等产生变形、强度下降或软化等改变药物的释放特征。材料与血液产生相互作用的称为血液相容性。例如,某些高分子材料注射进入血管后,材料表面吸附血浆蛋白,血小板粘附、聚集、变形,最终可引起血栓等[6]. 许多高分子材料的安全性问题不仅与高分子本身性质有关,可能也与高分子生产

秦岭地区徒步穿越路线大全

秦岭地区徒步穿越路线大全 1、秦岭太白山穿越 路线一:都督门-铁甲树南南穿越 厚昣子——老县城——都督门——老庙子——跑马梁——大爷海——拔仙台——南天门——铁甲树——厚昣子 太白穿越经典线路之一,一路可体验石海、大梁、林海、云海和高山湖泊的景色,拔高强度大,一般徒步需3天时间,来回乘车一天。 难度:3级 强度:3级半 冒险指数:2级半(仅跑马梁一段无明显路,其余较明显) 风景指数:4级 原始指数:3级 穿越时间:4天 海拔高度:最高3767,大部分时间3000米以上。 路线二:都督门-鹦哥或营头 厚昣子——老县城——都督门——老庙子——跑马梁——大爷海——大文公——放羊寺——明星寺——平安寺——鹦哥或营头

太白穿越最经典线路。秦岭所有壮丽景色均可一览无遗,也是最艰苦的穿越线路,一般徒步需4天,来回乘车一天。 难度:4级 强度:4级半 冒险指数:3级(除跑马梁外路线较明) 风景指数:5级 原始指数:3级 穿越时间:5天 海拔高度:最高3767,大部分时间3000米以上。 路线三:铁甲树--鹦哥或营头 厚昣子——铁甲树——南天门?——大爷海——大文公——放羊寺——明星寺——平安寺——鹦哥或营头 常规路线。如体力一般还可到大文公后从汤峪坐索道出。景色也非常美,但缺少在无边无际大梁上行走的一段路线,有些遗憾。另该线路走的人多,垃圾较多。 难度:3级 强度:3级半 冒险指数:2级 风景指数:4级 原始指数:3级 穿越时间:4天 海拔高度:最高3767,大部分时间3000米以上。 太白汤峪旅游线路和不常规线路不说了。 2、首阳山穿越

耿峪——将军石——熊岔——首阳——熊岔——观音山——耿峪 尽管海拔不高,首阳顶才2700多米,但强度非常大,很短的距离内上下拔高1000多米。个人感觉强度与太白相当,很多人在此线路上走扯。首阳相传伯夷、叔齐不食周粟饿死而保气节的地方,顶上有大片草甸和首阳庙,是一处徒步观大气风景的好地方。 难度:3级 强度:4级 冒险指数:2级 风景指数:2级 原始指数:3级 穿越时间:2天 海拔高度:2720米 3、鳌山穿越

秦岭七十二峪 详细介绍

秦岭七十二峪详细介绍 临渭2个箭峪奓峪 蓝田7个清峪扯袍峪东汤峪小洋峪岱峪辋峪道沟峪 长安16个库峪土门峪石砭峪太峪蛟峪天子峪抱龙峪高冠峪子午峪祥峪沣峪皇峪白石峪大峪白道峪小峪 户县11个紫阁峪甘峪乌桑峪黄柏峪化羊峪烧柴峪涝峪潭峪粟裕鸽勃峪太平峪周至7个耿峪竹峪西骆峪黑峪就峪田峪赤峪 眉县6个泥峪斜峪大黑峪小黑峪滑峪西汤峪 库峪路线:长安区-杜曲-引镇-库峪乡 大峪自然风景区位于长安区秦岭山脉,距西安市区45公里。风景区内溪流潺潺,水潭清澈见底,潭瀑相连,景色优美,沿途随处可见蝴蝶翩翩飞舞,花草树木郁郁葱葱,天赐顶上可欣赏到近200亩面积的高山草垫的独特地貌。路线:长安区-杜曲-引镇-大峪路线:长安区-杜曲-王莽-大峪 小峪在大峪西边位于西安东南秦岭山脉的小峪,距西安40多公里,那里风景如画,气侯宜人,民风纯朴,四季分明。从西安出发经长安路---韦曲---杜曲南3公里叉口左拐1KM王莽乡路口-----王莽乡-----向南5KM小峪水库-----进山7KM沙土路------小峪终点柳金坪(海拔1180米)。骑车到此为止,可将车寄存在老乡家,徒步顺羼羼小河逆流而上,绵延几十里山路风光无限!路线:长安区-杜曲-王莽-小峪 白道峪大峪、白道峪、小峪都在长安引镇境内,自东向西依次排列,[嘉午台]在三个峪的交汇地段。路线:长安县-杜曲-王莽-大峪-白道峪 石砭峪路线:长安区-子午镇-石砭峪 康峪蛟峪路线:长安区-杜曲-太乙宫-蛟峪 沣峪一直进山可以到达分水岭,分水岭从沣峪口上山,顺公路直上,34公里,到达秦岭顶,俗称分水岭。几个关键点要记住:黎园坪:你才刚开始。青岗树:你差不多走了一半多。鸡窝子:还有4公里,但你可能要一个小时才能上去。 路线:太白路-沣峪口-沣峪 天子峪长安县王庄天子峪百塔寺遗址的隋代银杏,当地乡民视为“神树”,过去在树上挂满了祈福的各色布条,已求吉祥平安。路线:长安-王庄抱龙峪子午大道南口向东约1km向南进子午镇,向南穿过镇子,顺路直走,约3km土路,过一桥,约1.5km水泥路到航天基地。路左有一小桥,过河可穿越到天子峪。顺路直走,约3km骑车到此为止,可将车寄存在老

医用高分子材料论文

医用高分子材料 高分子材料科学与工程,高材1006班,王中伟,20100221276 摘要:随着高分子材料在社会的各个领域的广泛应用,尤其是在航天工程、医学等领域的应用。功能高分子材料一般指具有传递、转换或贮存物质、能量和信息作用的高分子及其复合材料,或具体地指在原有力学性能的基础上,还具有化学反应活性、光敏性、导电性、催化性、生物相容性、药理性、选择分离性、能量转换性、磁性等功能的高分子及其复合材料。医用高分子材料是用以制造人体内脏、体外器官、药物剂型及医疗器械的聚合物材料。对医用高分子材料的目前需求作了简要分析,介绍了医用高分子材料的主要类别、用途及其特殊要求,并浅谈了医用高分子材料的发展及展望。 关键词:医用高分子材料人工人体器官对人类健康的促进相容性 前言:现代医学的发展,对材料的性能提出了复杂而严格的多功能要求,这是大多数金属材料和无机材料难以满足的;而合成高分子材料与生物体(天然高分子)有着极其相似的化学结构,化学结构的相似性决定了它们在性能上能够彼此接近从而可能用聚合物制作人工器官,作为人体器官的替代物。另外,除人工器官用材料之外, 医药用高分子材料、临床检查诊断和治疗用高分子材料的开发研究也在积极地展开,它们被统称为医用高分子材料.医用高分子材料是一类令人瞩目的功能高分子材料,是一门介于现代医学和高分子科学之间的新兴学科。它涉及到物理学、化学、生物化学、医学、病理学等多种边缘学科。医用高分子材料是生物材料的重要组成部分。医用高分子材料是一类可对有机体组织进行修复、替代与再生,具有特殊功能作用的新型高技术合成高分子材料,是科学技术中的一个正在发展的新领域,不仅技术含量和经济价值高,而且对人类的健康生活和社会发展具有极其重大意义,它已渗入到医学和生命科学的各个部门并应用于临床的诊断与治疗。 正文: 一、医用高分子材料的概念及简介:医用高分子材料是依据高分子材料的某些特性及特征, 如其本身是惰性的,不参与药的作用,能只起增稠、表面活性、崩解、粘合、赋形、润滑和包装等特效,对有机体组织进行修复、替代与再生,具有特殊功能作用的新型高技术合成高分子材料,用它制造成能有医学价值的产品。医用高分子材料是一类令人瞩目的功能高分子材料,是一门介于现代医学和高分子科学之间的新兴学科。它涉及到物理学、化学、生物化学、医学、病理学等多种边缘学科。医用高分子材料是生物材料的重要组成部分。是科学技术中的一个正在发展的新领域,不仅技术含量和经济价值高,而且对人类的健康生活和社会发展具有极其重大意义,它已渗入到医学和生命科学的各个部门并应用于临床的诊断与治疗。然而,医用高分子材料是一类根据医学的需求

秦岭环山路沿线登山路线汇总

一、石砭峪大瓢沟 大瓢沟位于石砭峪水库以上约五里路处,紧挨熊沟。与南五台,翠花山相望。口小内大,形似葫芦而得名。沟内视野开阔,农家错落有致,庭院清爽,松林成荫,竹林茂密,寺庙禅音飘荡,如到净土。庙内九十岁高龄名僧盛名远播,弟子遍及海内外。欲大兴土木,回报师傅。 登临山颠庙宇,听禅音远荡,看松生旷,望层峦叠嶂,观芸芸众生,山话静放,顿有宠辱皆忘,忧烦顿消,如沐春风,使人顿生,遁世之意,真乃修身养性,参禅悟道,天赐福地.小瓢沟沟长幽深,山体嵯峨,林木燥干,溪河水欢,一路听喜鹊叫枝,看竹林诉青。过北池灵一组农家,穿松树林,过豁口,直走正沟,悠扬的佛音缭绕,寺院群山环保中显得峻险秀媚高远神秘。俯瞰沙梁子,直接石砭峪水库;东面背倚青峰山,远接北沟梁;南面青岔,五指山;北面熊沟,石沟梁,地势险要,蔚为壮观,四周环绕山峰宛若莲花瓣。 穿越行程30里。 二、大峪莲花洞 莲花洞是一古洞群,是天然形成的钟乳石景,最奇特的是一朵高约3米,径宽2.5米的倒挂石莲花,相传有千年历史。莲花洞因此得名。莲花洞景区由大峪口进山,远空天高云淡,山峦苍翠延绵,大峪水库波光闪闪,大峪河水北去潺潺.五里庙下车后健步南行,青山俊秀苍劲,山村悠然恬淡。 三、太平峪内情侣溪 情侣溪在太平峪内,又叫“石公岔”,别名二道沟,植被丰茂,水流湍急.因浪漫故事相传故得名情侣溪。 沿弯弯山道,伴湍急溪水,喜鹊鸣枝,杂树斑斓,山谷幽静,鸟语云端;曲径通幽处,溪道跌宕,溪水潺潺,溪潭众多(约10多个潭子),潭水清冽,冰凉肌肤;随意溪石,藤蔓林立,空谷寂静,群山怀绕,鸟语天籁,柳风拂面,波影幽幽水,青光皓洁天,湿润的空气,清香的花瓣。 户县太平峪东寺沟登高穿越 东寺沟位于户县秦岭户县太平峪深处约10公里处,为西寺沟斜对面之广阔山梁,远望山势舒缓(高约1200米),梁上林木招展,沿林间野径盘山,过坡田林荫,问顶东寺山野人家,大定寺寂寞残破,穷人家秋实满院,攀高山野丛林,上抵三台阔野密境,舒展欢歌,休憩望远,周山茫茫,秋高气爽,午后绕行东寺南侧野径,下东寺溪流,捡拾清流归家。此团意登高健行观俗购物(核桃,板栗等)全程行山20-25里,不走回头路。

关于秦岭人文生态旅游度假圈调研报告通用范本

内部编号:AN-QP-HT263 版本/ 修改状态:01 / 00 In Order T o Standardize The Management, Let All Personnel Enhance The Executive Power, Avoid Self- Development And Collective Work Planning Violation, According To The Fixed Mode To Form Daily Report To Hand In, Finally Realize The Effect Of Timely Update Progress, Quickly Grasp The Required Situation. 编辑:__________________ 审核:__________________ 单位:__________________ 关于秦岭人文生态旅游度假圈调研报 告通用范本

关于秦岭人文生态旅游度假圈调研报告 通用范本 使用指引:本报告文件可用于为规范管理,让所有人员增强自身的执行力,避免自身发展与集体的工作规划相违背,按固定模式形成日常报告进行上交最终实现及时更新进度,快速掌握所需了解情况的效果。资料下载后可以进行自定义修改,可按照所需进行删减和使用。 按照局里统一部署,陈清亮副局长率领赴宝鸡调研组先后深入xx市xx县、xx县、xx 县、xx县、xx区、xx区及高新区等七个县(区)和xx市文化旅游建设开发管委会,就开发大秦岭人文生态旅游度假圈工作开展调查研究。调研情况如下: 一、xx市秦岭生态旅游发展情况和取得的经验 秦岭横亘xx市6个县区56个乡镇。近年来,xx市委、市政府提出建设旅游名市的思路,依托秦岭丰富的旅游资源,积极开发生态

数字林业(秦岭)建设方案

数字林业(秦岭)建设方案 2020年07月

一、项目背景 秦岭是位于中国中部东西走向的巨大山脉,西起甘肃、青海,东到河南省西部,主体位于陕西省南部与四川省北部交界处,呈东西走向,长约1600公里。秦岭是中国南北分界线,长江流域与黄河流域的分水岭。秦岭北坡短而陡,水流急湍,多山涧深谷,峰峦叠嶂,云雾缭绕,山涧河谷和盆地构成特别秀丽的风光,为生态旅游之胜地。有“秦岭七十峪”之称。 秦岭范围700多平方公里,重点监管范围主要以秦岭生态保护区的“五乱”现象为主,联合相关职能部门对秦岭生态保护区的产业、旅游、矿产、水土保持、水资源保护、封山育林进行统一管理。 为了提升秦岭的生态治理、环境监测和综合办公及服务的能力,秦岭的信息化建设需求日趋紧迫,“数字林业(秦岭)”成为信息化建设的必然趋势。为了整合资源,提高工作效率,建立高效的调度和联动的工作基础设施,结合秦岭特殊的政治、地理、经济的特殊地位,以防止“五乱”为基础打造“美丽秦岭”、“智慧旅游”等系列解决方案;提升秦保办工作人员的工作效率,丰富服务旅客的方式,打造新型智慧秦岭。

二、需求分析 数字林业(秦岭)项目建设以履行秦岭生态环境保护职责、满足秦岭保护局数字信息化监管的需求、保持信息资源的可持续开发利用为目标。综合应用云计算、大数据、物联网、移动互联网、人工智能等信息技术,形成智能化、网格化、精准化的生态环境保护系统,创新秦岭生态环境保护监管模式,对秦岭进行全域监管,对重点区域进行全时监管,提升秦岭生态环境保护科学决策规划能力,增强秦岭生态环境精细化监管和行政执法效能,促进生态环境保护管理体制机制的创新与完善,筑牢秦岭生态安全屏障。 二、整体规划 (一)数字林业(秦岭)平台 依托数字林业(秦岭)“一张图”平台能力,具体功能包括: 1)、实现各类委办局视频监控的统一纳管。包括:前端监控视频采集、视频传输、指挥中心呈现、图像解析、无人机巡查监控、火情监控报警等功能。 2)、依托平台的成熟建模与大数据能力,对既有环保、、城管、游客服务版块各业务(例如服务事项)实现数据统计分析与交互能力,并能够实现大数据的预测研判。

陕西秦岭56个峪的入口

陕西秦岭56个峪的入口,你知道几个? 大秦岭其中56个峪的入口 1、清峪:峪口位于蓝田县玉山镇腰祝村和厚镇乡官道村之间,环山旅游公路经过清峪口。进峪口约3公里分岔,往东的沟较短,通往厚镇乡北峪村;岔口往东南方向是清峪,峪内有清峪庙、青峰村、高升村。 2、道沟峪:峪口位于蓝田县蓝田人遗址、玉山镇和九间房乡三角地带。在环山旅游公路上,道沟峪和流峪已经会合。从玉山镇前程村下环山旅游公路往东约1公里分岔,向东是道沟峪,向南是流峪。道沟峪自下而上呈向东偏南走向,可到灞源乡灞河源头。 3、流峪:峪口位于蓝田县蓝田人遗址、玉山镇和九间房乡三角地带。从玉山镇前程村下环山旅游公路,拐向省道S101,南行约3公里到九间房乡峪口村,再行约1公里到柿园子村。峪内有蓝田流峪飞峡生态旅游区,有景点:登天门,999级登天梯,天池,天河瀑布,龙宫瀑布,仙游瀑布,飞峡瀑布,遇仙亭,野风寨,猴头山,象山,古宅探秘风景区,后山原始部落风景区,山神庙,观景台。流峪西面有王顺山国家森林公园。 4、赛峪:峪口位于蓝田县普化镇韩门寨村,环山旅游公路经过峪口。赛峪长度较短,大部分属王顺山国家森林公园。王顺山,又名玉山、蓝田山,海拔2324米。“玉山并秀”是蓝田八景之一。 5、辋峪:峪口位于蓝田县蓝关镇榆林村东,环山旅游公路与沪陕高速公路交叉口以西。峪内有辋河峡谷漂流项目。峪内辋川乡往东,经五星村,可到锡水庙和辋川溶洞。辋川乡往南有董家岩瀑布。“辋川烟雨”是蓝田八景之一。沪陕高速沿辋峪穿越秦岭。 6、岱峪:峪口位于蓝田县焦岱镇。从焦岱镇下环山旅游公路,南行约2公里(未到小寨乡关庙村)分岔,东面去岱峪,西面往小洋峪。 7、小洋峪:峪口位于蓝田县焦岱镇。从焦岱镇下环山旅游公路,南行约2公里(未到小寨乡关庙村)分岔,西面往小洋峪,东面去岱峪。沿小洋峪一直往南,可以到达海拔2224米的云台山。 8、大洋峪:峪口位于蓝田县焦岱镇。从焦岱镇下环山旅游公路即到峪口。沿大洋峪一直往南,可以到达海拔2224米的云台山。 9、东汤峪:位于蓝田县西南部,汤峪镇在环山旅游公路南约4公里处。为与西面宝鸡市眉县的汤峪区别,称东汤峪。汤峪,古称石门谷,以温泉闻名。“石门汤泉”是蓝田八景之一。峪内开发有“汤峪旅游风景区”。从东汤峪可以登顶云台山。沿东汤峪可穿越秦岭,到商洛市柞水县丰北河乡瓦屋场村,然后到柞水县营盘镇。 10、库峪:峪口位于长安区杨庄乡库峪口村,离环山旅游公路约7公里。峪内十里庙村至西木斯村一线西侧有太兴山风景区。太兴山人称“终南第一峰”,海拔2340米。太兴山北侧有葫芦坡和锦鸡岭。库峪是穿越秦岭的古道之一。沿库峪可穿越秦岭,到商洛市柞水县丰北河乡王家沟村,然后到柞水县营盘镇。 11、扯袍峪:峪口位于长安区杨庄乡汪庄村,离环山旅游公路约6公里。峪长度仅有几公里。沿扯袍峪往南,可到人头山。 12、大峪:峪口位于长安区引镇大峪口村,离环山旅游公路约6公里。峪的西面由北向南依次有狮子茅棚、嘉午台、莲花洞等景点。沿大峪可穿越秦岭,到商洛市柞水县营盘镇。 13、白道峪:峪口位于长安区引镇白道峪村,离环山旅游公路约5公里。峪长度仅有几

高分子材料论文

高分子材料论文 在世界范围内, 高分子材料的制品属於最年轻的材料.它不仅遍及各个工业领域, 而且已进入所有的家庭, 其产量已有超过金属材料的趋势, 將是21世纪最活跃的材料支柱. 高分子材料是有机化合物, 有机化合物是碳元素的化合物.除碳原子外, 其他元素主要是氢、氧、氮等.碳原子与碳原子之间, 碳原子与其他元素的原子之间, 能形成稳定的结构.碳原子是四价, 每个一价的价键可以和一个氢原子键连接, 所以可形成为数众多的、具有不同结构的有机化合物.有机化合物的总数已接近千万种, 远远超过其他元素的化合物的总和, 而且新的有机化合物还不断地被合成出來.這样, 由於不同的特殊结构的形成, 使有机化合物具有很独特的功能.高分子中可以把某些有机物结构(又称为功能团)替换, 以改变高分子的特性.高分子具有巨大的分子量, 达到至少1万以上, 或几百万至千万以上, 所以, 人們將其称为高分子、大分子或高聚物.高分子材料包括三大合成材料, 即塑料、合成纤维和合成橡胶(未加工之前称为树脂). 面向21世纪的高科技迅猛发展, 带动了社会经济和其他产业的飞跃, 高分子已明确地承担起历史的重任, 向高性能化、多功能化、生物化三个方向发展.21世纪的材料將是一个光辉灿烂的高分子王国. 现有的高分子材料已具有很高的强度和韧性, 足以和金属材料相媲美, 我們日用的家 用器械、家具、洗衣机、冰箱、电视机、交通工具、住宅等, 大部分的金属构造已被高分子材料所代替.工业、农业、交通以及高科技的发展, 要求高分子材料具有更高的强度、硬度、韧性、耐温、耐磨、耐油、耐折等特性, 這些都是高分子材料要解决的重大问题.从理论上推算, 高分子材料的强度还有很大的潜力. 在提高高分子的性能方面, 最重要的还是制成复合材料第一代复合材料是玻璃钢, 是 以玻璃纤维和合成树脂为粘合剂制成.它具有重量轻、强度高、耐高温、耐腐蚀、导热系数低、易於加工等优良性能, 用於火箭、导弹、船只和汽车躯体及电视天线之中.其后, 人們把玻璃纤维换成碳纤维, 其重量更轻, 强度比钢要高3~5倍, 這就是第二代的复合材料.如果改用芳纶纤维, 其强度更高, 为钢丝的5倍.高性能的高分子材料的开拓和创新尚有极大的潜力.科学家预测, 21世纪初, 每年必须比目前多生产1500~2000万吨纤维材料才能满足需要, 所以必须生产大量的合成纤维材料, 而且要具有更轻型、耐火、阻燃、防臭、吸水、杀菌等特性.有许多新型纤维, 如轻型空腔纤维、泡沫纤维、各种截面形状的纤维、多组份纤维材料等纷纷被研制出來, 人們可指望会有耐静电、耐脏、耐油, 甚至不会沾灰的纤维材料问世.這些纤维材料將用於宇航天线、宇航反射器、心脏瓣膜和人体大动脉. 高分子功能材料, 在高分子王国里是一片百花争艳的盛景.由於高分子的功能团能够替代, 所以只要采用极为简便的方法, 就可以制造各种各样的高分子功能材料.常用的吸水性

秦岭古道

秦岭古道 -----四大古道和四小古道 作为中国南北气候分界、长江黄河流域分水岭的秦岭,是横亘在关中盆地与商州盆地、安康盆地、汉中盆地之间的大山,自古以来当地人们因各种往来目的,就在秦岭的峪中劈山填石、架设栈道,从而开辟了许多条翻越秦岭的古道。秦岭中的古道有这四大古道,还有四小古道。事实上,在这四大古道以东,就是古代由关中通往东南方向的安康岭南还有四个古道,就是所谓的四小古道。他们分别是:蓝武道,库谷道、义谷道和锡谷道。 秦汉地图 更多地图:https://www.wendangku.net/doc/c517262460.html,/NBArticle/article.asp?articleid=1090

子午道:从长安区的子午峪进入再翻越到沣峪,沿河谷上行穿越秦岭到石泉县,向东可进入安康盆地,向西可进入汉中盆地。唐代诗人杨凝的《送客入蜀》中有诗句“明朝骑马摇鞭去,秋雨槐花子午关。”,李白的《答长安崔少府叔封游终南翠微寺太宗皇帝金沙泉见寄》中也有诗句“早行子午关,却登山路远。拂琴听霜猿,灭烛乃星饭。”,说的都是这里;子午道由长安沿沣河上行,越秦岭经宁陕、石泉达汉中。这条道有新旧两线,古道乃汉魏时期顺池河下行至石泉;六朝后的新线才是经江口、宁陕达石泉,全程520公里。 秦汉魏晋时期,子午道的大致经行路线为:自古长安南下,经今西安南郊杜城村,入今长安县子午镇附近子午谷,溯谷而上至土地梁,越梁沿沣水支流至喂子坪附近沣水河谷,溯谷南行至关石(即子午关,又名石羊关);过关石后南行,越秦岭主脊到宁陕县沙沟街,循汉江支流旬河而下,经高关场、江口镇、沙坪街、大西沟,翻越月河梁至月河坪,南渡月河顺腰竹沟行,于古桑墩附近越腰竹岭进入汉江另一支流池河沿,循池河南下,经营盘、胭脂坝、新矿、龙王街、铁炉镇入石泉县境,经梧桐寺、迎风街、石佛寺、筷子铺、后营至池河镇,过马岭关绕汉江北侧九里十三湾至石泉县城;自石泉县城向西北,经古堰、绕峰街至西乡县子午镇,过子午河入洋县境,复经金水镇、酉水镇、龙亭进入汉江平原,过洋县、城固县城到达汉中。 唐代“涪洲贡生荔枝,取道西乡驿站沿子午河入谷,至长安不过三日”。在秦岭诸道中,子午道最为冷落,天宝年间从四川涪陵运送新鲜荔枝到长安,为使荔枝色味不变,才取捷近的子午道。 子午道北段地图,北起子午镇北豆角村,这儿还有老城门。

秦岭七十二峪旅游

秦岭七十二峪详细介绍 1、库峪路线:长安区-杜曲-引镇-库峪乡 2、大峪大峪自然风景区位于长安区秦岭山脉,距西安市区45公里。风景区内溪流潺潺,水潭清澈见底,潭瀑相连,景色优美,沿途随处可见蝴蝶翩翩飞舞,花草树木郁郁葱葱,天赐顶上可欣赏到近200亩面积的高山草垫的独特地貌。 路线:长安区-杜曲-引镇-大峪 路线:长安区-杜曲-王莽-大峪 3、小峪在大峪西边 位于西安东南秦岭山脉的小峪,距西安40多公里,那里风景如画,气侯宜人,民风纯朴,四季分明。 从西安出发经长安路---韦曲---杜曲南3公里叉口左拐1KM王莽乡路口-----王莽乡-----向南5KM小峪水库-----进山7KM沙土路------小峪终点柳金坪(海拔1180米)。 骑车到此为止,可将车寄存在老乡家,徒步顺羼羼小河逆流而上,绵延几十里山路风光无限!路线:长安区-杜曲-王莽-小峪 4、白道峪大峪、白道峪、小峪都在长安引镇境内,自东向西依次排列,[嘉午台]在三个峪的交汇地段。 路线:长安县-杜曲-王莽-大峪-白道峪 5、石砭峪路线:长安区-子午镇-石砭峪 6、康峪 蛟峪路线:长安区-杜曲-太乙宫-蛟峪 7、沣峪一直进山可以到达分水岭 路线:太白路-沣峪口-沣峪 8、天子峪长安县王庄天子峪百塔寺遗址的隋代银杏,当地乡民视为“神树”,过去在树上挂满了祈福的各色布条,已求吉祥平安。 路线:长安-王庄 9、抱龙峪 子午大道南口向东约1km向南进子午镇,向南穿过镇子,顺路直走,约3km土路,过一桥,约1.5km水泥路到航天基地。路左有一小桥,过河可穿越到天子峪。顺路直走,约3km骑车到此为止,可将车寄存在老乡家,徒步顺路而上,约半小时路程可见抱龙瀑布(冬季为异常壮观的冰瀑)。 路线:长安县—子午镇—抱龙峪 10、子午峪入口不久南豆角村中可见一佛头,高约1.5米。 子午峪穿越路线:子午峪口-七里坪-土地梁-碌碡坪-枣儿岭(他二婶农家附近?)-210国道-沣峪口子午峪进山,可直接骑行至七里坪,之后山路窄,40cm宽度,至土地梁一段推行约1.5小时,其间上坡,土路,石级,平缓路段兼有。土地梁至碌碡坪为下坡路段,路面窄,难以骑行,接近碌碡坪处路面变宽,可通过农用车。碌碡坪至枣儿岭段其间有一上坡,需翻过一梁,路面情况复杂,平坦,碎石,泥土路兼有。枣儿岭至210国道路面平坦,出口在超限检查站南口处。 路线:长安区-子午大道-子午峪 11、太乙峪传汉武帝到太乙湫池祭太一神、建太乙宫,谷随宫名。 太乙峪及附近爬山线路有:翠华山(甘湫池);营盘反串翠华山;南五台-太乙峪穿越;蛟峪等; 12、太和峪大约在长安区滦镇,翠微宫附近 13、皇峪野生动物园

医用高分子材料

刘熙高分子092班 5701109065 生活中的高分子材料 ——医用高分子材料 摘要:我国医用高分子材料的研究起步较早、发展较快。医用高分子材料指用于生理系统疾病的诊断、治疗、修复或替换生物体组织或器官,增进或恢复其功能的高分子材料。医用高分子材料属于一种特殊的功能高分子材料,通常用于对生物体进行诊断、治疗、以及替换或修复、合成或再生损伤组织和器官,具有延长病人生命、提高病人生存质量等作用。 关键词:生物医用高分子材料 科技关爱健康,医用高分子材料的应运而生是医疗技术发展史上的一次飞跃。高分子材料充分体现了人类智慧,是人类科学技术的重要科技进步成果之一。高分子材料:macromolecular material,以高分子化合物为基础的材料。高分子材料是由相对分子质量较高的化合物构成的材料,包括橡胶、塑料、纤维、涂料、胶粘剂和高分子基复合材料,高分子是生命存在的形式。所有的生命体都可以看作是高分子的集合。 而医用高分子材料是一类可对有机体组织进行修复、替代与再生, 具有特殊功能作用的合成高分子材料, 可以利用聚合的方法进行制备, 是生物医用材料的重要组成之一。由于医用高分子材料可以通过组成和结构的控制而使材料具有不同的物理和化学性质, 以满足不同的需求, 耐生物老化, 作为长期植入材料具有良好的生物稳定性和物理、机械性能, 易加工成型, 原料易得, 便于消毒灭菌, 因此受到人们普遍关注, 已成为生物材料中用途最广、用量最大的品种, 近年来发展需求量增长十分迅速。目前全世界应用的90多个品种, 西方国家消耗的医用高分子材料每年以10%~20%的速度增长。以美国为例, 每年有数以百万计的人患有各种组织、器官的丧失或功能障碍, 需进800万次手术进行修复, 年耗资超过400亿美元, 器官衰竭和组织缺损所需治疗费占整个医疗费用的一半。随着人民生活水平的提高和对生命质量的追求, 我国对医用高分子材料的需求也会不断增加。

功能高分子材料论文

生物医用高分子材料 摘要:简述了对功能高分子材料的认识,功能高分子材料的特征和功能高分子材料的分类,接着重点写生物医用高分子的发展前景和趋势,对生物医用功能高分子的认识和其重要性的认识。 关键词:功能高分子材料,生物医用高分子材料。 功能高分子材料 功能高分子材料一般指具有传递、转换或贮存物质、能量和信息作用的高分子及其复合材料,或具体地指在原有力学性能的基础上,还具有化学反应活性、光敏性、导电性、催化性、生物相容性、药理性、选择分离性、能量转换性、磁性等功能的高分子及其复合材料。功能高分子材料是上世纪60年代发展起来的新兴领域,是高分子材料渗透到电子、生物、能源等领域后开发涌现出的新材料。近年来,功能高分子材料的年增长率一般都在10%以上,其中高分子分离膜和生物医用高分子的增长率高达50% 所谓功能性高分子材料,一般是指具有某种特别的功能或者是能在某种特殊环境下使用的高分子材料,但这是相对于一般用途的通用高分子材料而言。这一定义只是一个概括,不一定很确切,较多的人认为所谓功能性高分子材料是指具有物质能量和信息的传递、转换和贮存作用的高分子材料及其复合材料。如有光电、热电、压电、声电、化学转换等功能的一些高分子化合物。可以看出,这是一类范围相当大、用途相当广、品种相当多,而又是在生活、生产活动中经常遇见的一类高分子材料。 功能高分子材料按照功能特性通常可分成以下几类: (1)分离材料和化学功能材料;(2)电磁功能高分子材料;(3)光功能高分子材料;(4)生物医用高分子材料。功能高分子材料是高分子学科中的一个重要分支,它的重要性在于所包含的每一类高分子都具有特殊的功能。 随着时代的发展,在医学领域中越来越迫切地需要开发出能应用于医疗的各种新型材料,经多年的研究已发现有多种高分子化合物可以符合医用要求,我们也把它归属于功能性高分子材料。 一般归纳起来医用高分子材料应符合下列要求: 1、化学稳定性好,在人体接触部分不能发生影响而变化; 2、组织相容性好,在人体内不发生炎症和排异反应; 3、不会致癌变;

秦岭古道

秦岭古道 作为中国南北气候分界、长江黄河流域分水岭的秦岭,是横亘在关中盆地与商州盆地、安康盆地、汉中盆地之间的大山,自古以来当地人们因各种往来目的,就在秦岭的峪中劈山填石、架设栈道,从而开辟了许多条翻越秦岭的古道。长安附近比较有名的6条古道是: 蓝武道:从蓝田县的辋峪东侧翻山进入蓝峪河谷,沿河谷上行穿越秦岭到达商州,在商州盆地的丹凤县就可以接上丹江水路,可进入河南和湖北境内。唐代诗人韩愈的诗句“云横秦岭家何在,雪拥蓝关马不前。”、唐代诗人李逢吉的诗句“冰雪背秦岭,风烟经武关。”中的蓝关和武关就是在蓝武道上; 库谷道:从长安区的库峪、大峪、小峪进入都可以,沿河谷上行穿越秦岭到达柞水县,进而沿乾佑河谷南行到达安康盆地; 子午道:从长安区的子午峪进入再翻越到沣峪,沿河谷上行穿越秦岭到石泉县,向东可进入安康盆地,向西可进入汉中盆地。唐代诗人杨凝的《送客入蜀》中有诗句“明朝骑马摇鞭去,秋雨槐花子午关。”,李白的《答长安崔少府叔封游终南翠微寺太宗皇帝金沙泉见寄》中也有诗句“早行子午关,却登山路远。拂琴听霜猿,灭烛乃星饭。”,说的都是这里; 傥骆道:从周至县的西骆峪进入,从厚畛子镇穿越秦岭到达洋县华阳古镇,再向南可以进入汉中盆地; 褒斜道:从眉县的斜峪进入,沿石头河谷上行穿越秦岭到达太白县,再向南沿褒河河谷就可以到达汉中盆地。唐诗中反映褒斜道的有,岑参的诗句“巴汉空水流,褒斜惟鸟飞。”、杜甫的诗句“长云湿褒斜,汉水饶巨石。”、白居易的诗句“途穷平路险,举足剧褒斜。”等等; 陈仓道:从宝鸡市区向南,沿清江河上行,过大散关穿越秦岭,沿嘉陵江河谷下行,可一直到达广远市,进入四川盆地。 在唐诗中可以看出,从唐长安城向东南、正南和西南三个方向上的蓝武道、子午道和褒斜道应该是那个年代的官道,我们也可以叫做唐朝的国道,而且这国道一用就是一千多年。上世纪新中国成立后,陕西省陆续修通了一些穿越秦岭的国道和省道,西安附近穿越秦岭的国道有: 312国道:从蓝田县蓝峪进入,基本沿着蓝武古道翻越秦岭到达商州,向东南方向通往河南、湖北地区; 210国道:从长安区沣峪进入,基本沿着子午古道翻越秦岭到达安康地区,向南方向可以通往重庆地区;

相关文档