Ionic conductivity of the aqueous layer separating a lipid bilayer membrane and a glass support

The in-plane ionic conductivity of the approximately 1-nm-thick aqueous layer separating a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) bilayer membrane and a glass support was investigated. The aqueous layer conductivity was measured by tip-dip deposition of a POPC bilayer onto the surface of a 20- to 75-microm-thick glass membrane containing a single conical-shaped nanopore and recording the current-voltage (i-V) behavior of the glass membrane nanopore/POPC bilayer structure. The steady-state current across the glass membrane passes through the nanopore (45-480 nm radius) and spreads radially outward within the aqueous layer between the glass support and bilayer. This aqueous layer corresponds to the dominant resistance of the glass membrane nanopore/POPC bilayer structure. Fluorescence recovery after photobleaching measurements using dye-labeled lipids verified that the POPC bilayer maintains a significant degree of fluidity on the glass membrane. The slopes of ohmic i-V curves yield an aqueous layer conductivity of (3 +/- 1) x 10(-3) Omega(-1) cm(-1) assuming a layer thickness of 1.0 nm. This conductivity is essentially independent of the concentration of KCl in the bulk solution (10-4 to 1 M) in contact with the membrane. The results indicate that the concentration and mobility of charge carriers in the aqueous layer between the glass support and bilayer are largely determined by the local structure of the glass/water/bilayer interface.     

SeTe8Sb1非晶合金的玻璃转变

The process of glass transition on the non-crystal SeTe_8Sb_1 has been researched using low temperature differential scanning calorimetry (DSC). The following conclusions are deduced: this process is a second-order phase transformation, the stronger endotherm displayed in it is imputed to hysteresis of the transition. The temperature of glass transition in heating process decrease with reduction of the cooling rate while forming glass. The activation energy of glass transition quickly increases from 174 kJ·mol. (at quenching rate ~10~4 K·min~(-1)) to 399 kJ·mol~(-1). (at cooling rate ~10 K·min~(-1)) So that the glass obtained at lower cooling rate is more stable than that obtained at higher rate.     

掺杂CuInS2纳米晶玻璃的三阶非线性光学性质

采用溶胶-凝胶法结合气氛控制制备了CuInS2纳米晶玻璃. 利用X射线粉末衍射仪(XRD)和透射电子显微镜(TEM)对CuInS2纳米晶在玻璃中的形貌和微结构进行了表征, 并利用飞秒Z扫描技术对该玻璃的三阶非线性光学性质进行了研究. 结果表明, 在钠硼硅玻璃中形成了尺寸分布为10 nm左右的均一的CuInS2四方晶系纳米晶. 该玻璃体现出优良的三阶非线性光学性能, 其三阶非线性光学折射率γ、吸收系数β和极化率χ(3)分别为8.57×10-16 m2/W, 3.74×10-8 m/W和1.95×10-17 m2/V2.     

Silicate glass coated microchannels through a phase conversion process for glass-like electrokinetic performance

The surface modified polydimethylsiloxane (PDMS) microchannels show a much more inferior performance to the durable and reproducible glass chip. In this paper, a facile approach to preparing a silicate glass modified PDMS microchannel for glass-like performance is presented. This glass-like performance is made possible by a phase conversion of a preceramic polymer--allylhydridopolycarbosilane (AHPCS). The, several hundred nanometer thick, polymer that coats the PDMS channel is hydrolyzed to form hydrophilic silicate glass via phase conversion under an aqueous alkali condition. It is characterized by XPS, FTIR-ATR, AFM, and contact angle measurements. The silicate glass coated PDMS channel from AHPCS has an excellent solvent resistance, delivers a high electroosmotic flow (EOF) that is stable in the long-term (4.9±0.1×10(-4) cm(2) V(-1) s(-1)) and a reliable capillary electrophoresis (CE), which are comparable to those of native glass channels. Moreover, the silicate glass PDMS channel allows easy regeneration of the electrokinetic behavior, just as in a glass channel, by a simple treatment with alkali solution. This coating approach can be applied to other polymer substrates such as polyimide (PI).     

On-line chemiluminescence detection for isoelectric focusing of heme proteins on microchips

In this paper we present a sensitive chemiluminescence (CL) detection of heme proteins coupled with microchip IEF. The detection principle was based on the catalytic effects of the heme proteins on the CL reaction of luminol-H2O2 enhanced by para-iodophenol. The glass microchip and poly(dimethylsiloxane) (PDMS)/glass microchip for IEF were fabricated using micromachining technology in the laboratory. The modes of CL detection were investigated and two microchips (glass, PDMS/glass) were compared. Certain proteins, such as cytochrome c, myoglobin, and horseradish peroxidase, were focused by use of Pharmalyte pH 3-10 as ampholytes. Hydroxypropylmethylcellulose was added to the sample solution in order to easily reduce protein interactions with the channel wall as well as the EOF. The focused proteins were transported by salt mobilization to the CL detection window. Cytochrome c, myoglobin, and horseradish peroxidase were well separated within 10 min on a glass chip and the detection limits (S/N=3) were 1.2x10(-7), 1.6x10(-7), and 1.0x10(-10) M, respectively.     

Glass foam from window panes and bottle glass wastes

Glass foams are building materials that now compete with classic insulating polymeric and fiber materials for thermal enveloping. The low flammability, high chemical durability and thermal stability are distinct advantages over polymeric materials. The present paper proposes the possibility of producing glass foam using two types of recycled glass wastes (window panes and bottle glass) together with plaster wastes from used ceramic casting molds as foaming agent. Optical microscopy, measurements of apparent porosity and density, hydrolytic and chemical stability, as well as thermal conductivity were used in order to characterize the obtained glass foams as insulator materials for the building industry. The apparent porosity of glass foams ranges between 20.19–54.54% when using window glass wastes, and 18.77–51.75% with bottle glass wastes. Thermal conductivity was less than 0.25 W mK-1 for all the studied glasses. The obtained results confirm that there exists an alternative method for producing glass foams, for example, from glass wastes and used ceramic plaster molds, which are utilized as foaming agents with good chemical stability and insulating properties.     

Self-organized TiO2 nanorod arrays on glass substrate for self-cleaning antireflection coatings

Herein we report the direct fabrication of TiO(2) subwavelength structures with 1-dimensional TiO(2) nanorods on glass substrate through solvothermal process to form self-cleaning antireflection coatings. TiO(2) precursor solutions with different solvent constituents create TiO(2) nanorods with much different morphologies grown on glass substrates. Apiculate TiO(2) nanorods with vertical orientation are grown on the glass substrate which is solvothermally treated in the precursor solution containing ethylene glycol. This glass substrate exhibit the highest transmittance of 70-85% in the range of 520-800 nm and negligible absorption in visible light region (400-800 nm). Furthermore, the TiO(2) nanorod arrays show high hydrophobicity and photocatalytic degradation ability which offer the glass substrate self-cleaning properties for both hydrophilic and oily contaminants.     

Controlled pore glass chromatography of protein-sodium dodecyl sulphate complexes.

The inclusion of urea has been found to eliminate adsorption of protein-sodium dodecyl sulphate (SDS) complexes to controlled pore glass. Using buffer containing 6 M urea, 0.5% SDS and glass with pore diameter 12.3 nm, it is possible to determine protein molecular weights in the range 3500-12,000. Results with glass of larger pore diameter (25.5 nm) are similar to those reported in the absence of urea in the molecular-weight range 12,000-140,000. Controlled pore glass chromatography also permits the study of the relative importance of conformation free of charge effects for those proteins which deviate from the normal calibration curve for SDS-polyacrylamide gels.     

Effect of container material, storage time and temperature on determinations of cadmium levels in human urine

The effect of container material (polyethylene, polypropylene, polystyrene, borosilicate glass and flint glass), storage time (0-86 days), and temperature (22 degrees and 4 degrees ) on the cadmium content found by graphite-furnace atomic-absorption spectrometry for spiked and unspiked urine samples has been studied. No loss of cadmium occurred for at least 10 and 28 days when unspiked and spiked samples respectively, were stored in polyethylene containers at 22 degrees . For storage up to 3-4 days at 22 degrees , polypropylene, polystyrene, borosilicate glass and flint glass containers were also found suitable. Storage at 4 degrees was not effective in preventing loss of cadmium.     

Permanent-use haemofilter based on porous glass capillaries

Modules of surface-modified porous glass capillaries with a hydraulic conductivity of 0.25-0.70 ml min^-1 mmHg^-1 m^-2 were tested for suitability for clinical haemofiltration by ex vivo dog experiments and by in vitro perfusion. The results show that (1) the construction of reusable haemofilters based on porous glass capillaries is possible; (2) operational data of testmodules are comparable with hollow-fiber high-flux haemofilters based on asymmetric cellulose acetate membranes; and (3) blood-surface interaction of porous glass capillaries is characterized by protein deposition which entails very low protein cutoff.     

Fluorinated nanodiamond as a wet chemistry precursor for diamond coatings covalently bonded to glass surface

The chemical reaction between fluoro-nanodiamond (F-ND) powder, solubilized in o-dichlorobenzene, and a glass surface, functionalized with the silane coupling agent, 3-aminopropyltriethoxysilane (APTES), was found to proceed under heating at 130 degrees C for 24-40 h and to result in covalent bonding of F-ND particles to a glass substrate, forming a 10-40 nm thick nanocrystalline film. The observed process presents a novel and cost-effective approach to fabrication of diamond coatings on glass by using wet chemistry instead of CVD and can be extended to other materials.     

Cu7.2S4量子点玻璃的制备及三阶非线性光学性质

利用溶胶-凝胶法结合气氛控制合成了含Cu7.2S4量子点的玻璃. 通过热重-差热分析仪对干凝胶样品的热分解机制进行了分析, 并利用X射线粉末衍射仪、 X射线光电子能谱、 透射电子显微镜、 X射线能量色散谱)、 高分辨透射电子显微镜及选区电子衍射对 Cu7.2S4量子点在玻璃中的微结构进行了表征, 利用飞秒Z扫描技术研究了材料在800 nm的三阶非线性光学性质. 结果表明, 尺寸在9~21 nm之间的Cu7.2S4纳米晶已经在玻璃中形成, 该玻璃展示出了优异的三阶非线性光学性能, 其三阶非线性光学折射率(γ)、 三阶非线性吸收系数(β)和三阶非线性极化率[X(3)]分别为1.11×10-15 m2/W, 8.91×10-9 m/W和9.56×10-18 m2/V2.     

Effect of Ga2O3 on the spectroscopic properties of erbium-doped boro-bismuth glasses

The spectroscopic properties and thermal stability of Er3+-doped Bi2O3-B2O3-Ga2O3 glasses are investigated experimentally. The effect of Ga2O3 content on absorption spectra, the Judd-Ofelt parameters Omega t (t=2, 4, 6), fluorescence spectra and the lifetimes of Er3+:4I 13/2 level are also investigated, and the stimulated emission cross-section is calculated from McCumber theory. With the increasing of Ga2O3 content in the glass composition, the Omega t (t=2, 4, 6) parameters, fluorescence full width at half maximum (FWHM) and the 4I 13/2 lifetimes of Er3+ first increase, reach its maximum at Ga2O3=8 mol.%, and then decrease. The results show that Er3+-doped 50Bi2O3-42B2O3-8Ga2O3 glass has the broadest FWHM (81nm) and large stimulated emission cross-section (1.03 x1 0(-20)cm2) in these glass samples. Compared with other glass hosts, the gain bandwidth properties of Er+3-doped Bi2O3-B2O3-Ga2O3 glass is better than tellurite, silicate, phosphate and germante glasses. In addition, the lifetime of 4I 13/2 level of Er(3+) in bismuth-based glass, compared with those in other glasses, is relative low due to the high-phonon energy of the B-O bond, the large refractive index of the host and the existence of OH* in the glass. At the same time, the glass thermal stability is improved in which the substitution of Ga2O3 for B2O3 strengthens the network structure. The suitability of bismuth-based glass as a host for a Er3+-doped broadband amplifier and its advantages over other glass hosts are also discussed.     

The spectroscopic properties of Er(3+)-doped TeO(2)-Nb(2)O(5) glasses with high mechanical strength performance

(100-x)TeO(2)-xNb(2)O(5) (x=5-20) niobic tellurite glasses doped with 0.5 mol.% Er(2)O(3) were synthesized, and their thermal, mechanical, and spectroscopic properties were measured and compared to the properties of the typical 75TeO(2)-20ZnO-5Na(2)O (TZN) tellurite glass. The refractive index (n(d)), density (rho), and glass transition temperature (T(g)) of bulk glasses increase with the Nb(2)O(5) content. The Vickers microhardness (H(v)) of bulk glass in niobic tellurite glasses also increases with the Nb(2)O(5) content. The values (2.5-3.2GPa) of H(v) in the niobic tellurite glasses are 47-88% larger than that (1.7GPa) in TZN glass. The effect of Nb(2)O(5) content on absorption spectra, the Judd-Ofelt parameters Omega(t) (t=2, 4, 6), fluorescence spectra and the lifetimes of Er(3+):I(13/2) level were also investigated, and the stimulated emission cross-section was calculated from McCumber theory. With increasing Nb(2)O(5) content in the glass composition, the Omega(t) (t=2, 4, 6) parameters, fluorescence full width at half maximum (FWHM) of I(13/2) of Er(3+) increase, while the (4)I(13/2) lifetimes of Er(3+) decreases. Compared with TZN glass, the gain bandwidth properties of Er(3+)-doped TeO(2)-Nb(2)O(5) glass is much larger than in tellurite glass based TeO(2)-ZnO-Na(2)O system, bismush-based glass, germanate, and silicate glasses, which indicates that TeO(2)-Nb(2)O(5) glasses are better choice as a practical available host material for broadband Er(3+)-doped amplifier.     

Characterization of IgG Langmuir-Blodgett films immobilized on functionalized polymers

The bioactivity of anti-human IgG Langmuir-Blodgett (LB) films, the non-specific adsorption of protein and the topography of anti-IgG LB films have been studied for application in immunosensors. The antibody (AB) LB films were horizontally deposited on glass and functionalized polymers, such as carboxy-poly(vinyl chloride) (PVC-COOH), chloropropyl and aminopropyl sol-gel. The LB films were characterized by means of ellipsometry, atomic force microscopy (AFM) and bicinchoninic acid (BCA) protein test. The interpretation of ellipsometric data was performed using a one-layer model. Non-specifically adsorbed protein was desorbed by washing the IgG film in 0.5 M NaCl, 2 M NaCl and 1% N-cetyl-N,N,N-trimethylammoniumbromide detergent solution resulting in a 50% reduction of the film thickness. The mean thickness of an anti-IgG film on glass measured by ellipsometry, PVC-COOH and aminopropyl sol-gel was 9+/-2, 11+/-1 and 23+/-8 nm, respectively. According to the BCA test 6-8 mug antibody (AB) per slide was bound to the functionalized polymers, but only 3 mug AB per slide was adsorbed on glass. The average distance of anti-IgG granules as indicated by AFM measurements on PVC-COOH, chloropropyl and aminopropyl sol-gel was 42+/-20, 34+/-3 and 23+/-4 nm. The average distance of granular AB structures on glass, however, was 150+/-50 nm.     

Dosimetric and spectroradiometric investigations of glass filtered solar UV

The aims of this paper were to investigate how glass-filtered UV irradiances vary with glass thickness, lamination of the glass and the effect of solar zenith angle (SZA), and to measure the glass-filtered UV exposures to different receiving planes with a newly developed UVA dosimeter. Spectroradiometric and dosimetric techniques were employed in the experimental approach. The percentage of the glass-filtered solar UV compared to the unfiltered UV ranged from 59% to 70% and was influenced to a small extent by the glass thickness and the SZA. The laminated glass transmitted 11 to 12% and the windscreen glass transmitted 2.5-2.6%. The influence of the SZA was less for the thicker glass than it was for the thinner glass. The change in transmission was less than 14% for the SZA between 48 degrees and 71 degrees. There was negligible influence due to the SZA on the glass-transmitted UV of the laminated and windscreen glass. The influence of the glass thickness in the range of 2-6 mm on the percentage transmission was less than 16%. The influences of the glass thickness and the SZA on the glass-transmitted UV have been incorporated in the use of a UVA dosimeter for the glass-transmitted UV exposures. The UVA dosimeter was employed in the field to measure the glass-filtered UV exposures to different receiving planes. The UVA dosimeter reported has the potential for personal solar UVA exposure measurements.     

Low-temperature heat capacity of room-temperature ionic liquid, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide

Heat capacities of liquid, stable crystal, and liquid-quenched glass of a room-temperature ionic liquid (RTIL), 1-hexyl-3-methylimidazolium bis(trifluromethylsulfonyl)imide were measured between 5 and 310 K by adiabatic calorimetry. Heat capacity of the liquid at 298.15 K was determined for an IUPAC project as (631.6 +/- 0.5) J K(-1) mol(-1). Fusion was observed at T(fus) = 272.10 K for the stable crystalline phase, with enthalpy and entropy of fusion of 28.34 kJ mol(-1) and 104.2 J K(-1) mol(-1), respectively. The purity of the sample was estimated as 99.83 mol % by the fractional melting method. The liquid could be supercooled easily and the glass transition was observed around T(g) approximately 183 K, which was in agreement with the empirical relation, T(g) approximately ((2)/(3)) T(fus). The heat capacity of the liquid-quenched glass was larger than that of the crystal as a whole. In the lowest temperature region, however, the difference between the two showed a maximum around 6 K and a minimum around 15 K, at which the heat capacity of the glass was a little smaller than that of crystal.     

Single ion-channel recordings using glass nanopore membranes

Protein ion-channel recordings using a glass nanopore (GNP) membrane as the support structure for lipid bilayer membranes are presented. The GNP membrane is composed of a single conical-shaped nanopore embedded in a approximately 50 microm-thick glass membrane chemically modified with a 3-cyanopropyldimethylchlorosilane monolayer to produce a surface of intermediate hydrophobicity. This surface modification results in lipid monolayer formation on the glass surface and a lipid bilayer suspended across the small orifice (100-400 nm-radius) of the GNP membrane, while allowing aqueous solutions to fully wet the glass nanopore. The GNP membrane/bilayer structures, which exhibit ohmic seal resistances of approximately 70 GOmega and electrical breakdown voltages of approximately 0.8 V, are exceptionally stable to mechanical disturbances and have lifetimes of at least 2 weeks. These favorable characteristics result from the very small area of bilayer (10(-10)-10(-8) cm(2)) that is suspended across the GNP membrane orifice. Fluorescence microscopy and vibrational sum frequency spectroscopy demonstrate that a lipid monolayer forms on the 3-cyanopropyl-dimethylchlorosilane modified glass surface with the lipid tails oriented toward the glass. The GNP membrane/bilayer structure is well suited for single ion-channel recordings. Reproducible insertion of the protein ion channel, wild-type alpha-hemolysin (WTalphaHL), and stochastic detection of a small molecule, heptakis(6-O-sulfo)-beta-cyclodextrin, are demonstrated. In addition, the insertion and removal of WTalphaHL channels are reproducibly controlled by applying small pressures (-100 to 350 mmHg) across the lipid bilayer. The electrical and mechanical stability of the bilayer, the ease of which bilayer formation is achieved, and the ability to control ion-channel insertion, coupled with the small bilayer capacitance of the GNP membrane-based system, provide a new and nearly optimal system for single ion-channel recordings.     

A toner-mediated lithographic technology for rapid prototyping of glass microchannels

A simple, fast, and inexpensive masking technology without any photolithographic step to produce glass microchannels is proposed in this work. This innovative process is based on the use of toner layers as mask for wet chemical etching. The layouts were projected in graphic software and printed on wax paper using a laser printer. The toner layer was thermally transferred from the paper to cleaned glass surfaces (microscope slides) at 130 degrees C for 2 min. After thermal transference, the glass channel was etched using 25% (v/v) hydrofluoric acid (HF) solution. The toner mask was then removed by cotton soaked in acetonitrile. The etching rate was approximately 7.1 +/- 0.6 microm min(-1). This process is economically more attractive than conventional methods because it does not require any sophisticated instrumentation and it can be implemented in any chemical/biochemical laboratory. The glass channel was thermally bonded against a flat glass cover and its analytical feasibility was investigated using capacitively coupled contactless conductivity detection (C(4)D) and laser-induced fluorescence (LIF) detection.     

Physical stability and relaxation of amorphous indomethacin

The alpha- and beta-relaxation processes in amorphous indomethacin have been studied by using differential scanning calorimetry. The beta-process has been detected as a small endothermic peak that emerges before the glass transition step when reheating samples previously annealed in the temperature region -20 to +5 degrees C. The activation energy of the beta-process is approximately 57 kJ mol(-1), and shows an increase with increasing temperature as it approaches the glass transition region. In the glass transition region, the effective activation energy of relaxation decreases with increasing temperature from 320 to 160 kJ mol(-1). Heat capacity measurements have allowed for the evaluation of the cooperatively rearranging region in terms of the linear size (3.4 nm) and the number of molecules (90). The beta-relaxation fades below -30 degrees C, which provides a practical estimate for the lower temperature limit of physical instability in indomethacin. It is demonstrated experimentally that nucleation of indomethacin takes place in the temperature region of the beta-relaxation.