Synthesis and characterization of chiral smectic side‐chain liquid crystalline polysiloxanes and ionomers containing sulfonic acid groups

The synthesis of new chiral smectic A (S_A) side‐chain liquid crystalline polysiloxanes (LCPs) and ionomers (LCIs) containing 4‐allyloxy‐benzoyl‐4‐(S‐2‐ethylhexanoyl) p‐benzenediol bisate (ABB) as mesogenic units and 4‐[[4‐(2‐propenyloxy)phenyl]azo]benzenesulfonic acid (AABS) as nonmesogenic units is presented. The chemical structures of the monomers and polymers are confirmed by FTIR spectroscopy or ¹H–NMR. Differential scanning calorimetry (DSC), optical polarizing microscopy, and X‐ray diffraction measurements reveal that all the polymers P_I–P_IV and ionomers P_V–P_VI exhibit S_A texture. The results seem to demonstrate that the tendency toward the S_A‐phase region increases with increasing sulfonic acid concentration, and the thermal stability of the S_A phase is determined by the flexibility of the polymer backbones and the interactions of sulfonic acid groups. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2335–2340, 2001     

Understanding the Behavior of Native Point Defects in ZrC by First‐Principles Calculations

Phase stability and macroscopic performances of ZrC are closely related to the behavior of native point defects. In this study, structures and stabilities of native point defects in ZrC as well as diffusion of C‐related defects are investigated by first‐principles calculations. It is shown that the carbon vacancy (V_C) and interstitials (C_is) are the dominant native point defects in ZrC. Six types of C_i configurations: two C‐trimers, one C‐tetrahedron, and three C‐dimers are identified with low defect formation energies. The V_C has a high migration energy (4.39 eV) which suggests its low mobility in ZrC. The C_is have low diffusion energy barriers (from 0.26 to 1.29 eV) which lead to their high mobility. In addition, the impact of defects (V_C, V_Zr, Zr_C, and C_Zr) on bonding strengths of neighboring Zr–C bonds is discussed. Especially near V_C, the 1NN (nearest neighboring) and 2NN Zr–C bonds are strengthened but 4NN Zr–C bonds are weakened. Interestingly, the 3NN Zr–C bonds are almost not affected by the presence of V_C. These results may be closely related to the short‐range interactions and ordering of V_C in nonstoichiometric ZrC.     

Slow Relaxation Processes in CCTO Detected by Capacitance Versus Voltage Curves

The temperature and frequency dependence of capacitance versus voltage (C–V) curves was investigated for ceramic CaCu₃Ti₄O₁₂ samples sintered in atmospheres of vacuum, air and oxygen, respectively. A drastic capacitance rise at higher dc voltages and low ac frequencies was observed for all these CaCu₃Ti₄O₁₂CCTO samples, and it is especially strong for the sample sintered in vacuum, which has not been found previously. The shape as well as the asymmetry of the C–V curves suggest that the dielectric behavior is related to charged trap states. It also indicates that a slow relaxation process, which is strongly correlated with the re‐positioning of oxygen vacancies related trap charges, takes place in CCTO. The main trap charge relaxation process is thought to occur between the boundaries perpendicular and parallel to the external electric field, and the anisotropy of the defect dipoles provide the possibilities for trap charge repositioning which maybe the reason of the huge dielectric constant.     

Analysis of the fluorescence of mechanically processed defect-laden hexagonal boron nitride and the role of oxygen in catalyst deactivation

ABSTRACT

The use of hexagonal boron nitride (h-BN) as a non-metal heterogeneous catalyst has been a popular subject in research since the discovery of its catalytic properties in 2016. Previous work found that an activation step was necessary for producing an effective catalyst. Density functional theory (DFT) calculations indicate defect sites, such as nitrogen (V_N) and boron (V_B) vacancies, bind favourably to olefins, hydrogen, and oxygen. In particular, the visible fluorescence intensity of processed h-BN increased with the length of exposure to air. The fluorescence behaviour of dh-BN powders when exposed to air after exposure to species such as argon, propene, and carbon dioxide is presented. Density of state calculations for molecular and atomic oxygen bound to V_N and V_B show that this increase in fluorescence may be due to atomic oxygen binding to V_N. The fluorescence emission behaviour observed in dh-BN powders and its relationship to DOS of oxygen species bound to catalytically active defect sites provides a better understanding of potential deactivation modes for catalysts based on dh-BN.     

Large Bubble Sizes and Rise Velocities in a Bubble Column Slurry Reactor

The results are reported of an experimental study of the gas holdup, ?_G, large bubble diameter, d_Lb, and large bubble rise velocity, V_Lb, in a 0.1 m wide, 0.02 m deep and 0.95 m high rectangular slurry bubble column operated at ambient temperature and pressure conditions. The superficial gas velocity U was varied in the range of 0–0.2 m/s, spanning both the homogeneous and heterogeneous flow regimes. Air was used as the gas phase. The liquid phase used was C₉‐C₁₁ paraffin oil containing varying volume fractions (?_S = 0, 0.05, 0.10, 0.15, 0.20 and 0.25) of porous catalyst (alumina catalyst support, 10 % < 10 μm; 50 % < 16 μm; 90 % < 39 μm). With increasing slurry concentrations, ?_G is significantly reduced due to enhanced bubble coalescence and for high slurry concentrations the “small” bubbles are significantly reduced in number. By the use of video imaging techniques, it was shown that the large bubble diameter is practically independent of the gas velocity for ?_S > 0.05 and U > 0.1 m/s. The measured large bubble rise velocity V_Lb agrees with the predictions of a modified Davis‐Taylor relationship.     

Oxygen Ion Conduction in Bulk and Grain Boundaries of Nominally Donor‐Doped Lead Zirconate Titanate (PZT): A Combined Impedance and Tracer Diffusion Study

Oxygen ion conduction in Nd³⁺‐doped Pb(Zr_xTi_1?x)O₃ (PZT) was investigated by impedance spectroscopy and ¹⁸O‐tracer diffusion with subsequent secondary ion mass spectrometry (SIMS) analysis. Ion blocking electrodes lead to a second relaxation feature in impedance spectra at temperatures above 600°C. This allowed analysis of ionic and electronic partial conductivities. Between 600°C and 700°C those are in the same order of magnitude (10^?5–10^?4 S/cm) though very differently activated (2.4 eV vs. 1.2 eV for ions and electron holes, respectively). Oxygen tracer experiments showed that ion transport mainly takes place along grain boundaries with partly very high local ionic conductivities. Numerical analysis of the tracer profiles, including a near‐surface space charge zone, revealed bulk and grain‐boundary diffusion coefficients. Calculation of an effective ionic conductivity from these diffusion coefficients showed good agreement with conductivity values determined from impedance measurements. Based on these data oxygen vacancy concentrations in grain boundary and bulk could be estimated. Annealing at high temperatures caused a decrease in the grain‐boundary ionic conductivity and onset of additional defect chemical processes near the surface, most probably due to cation diffusion.     

Polymers with palladium nanoparticles as active membrane materials

A new in situ infusion method was used to incorporate small amounts (～1 wt %) of metal and metal oxide particles into a polymer matrix. Nanosized particles were observed by both transmission electron microscopy and atomic force microscopy. Oxygen (O₂) and carbon dioxide (CO₂) transport properties of the infused materials were investigated using a dynamic diffusion approach in which both testing and purge gases can be controlled. It was discovered that trace amounts (～2%) of hydrogen (H₂) in the purge gas were sufficient to considerably reduce the O₂ flux of FEP films infused with palladium (Pd) nanoparticles, up to a 200‐fold decrease. In contrast, H₂ essentially had no effect on the transport of CO₂. The generality of the remarkable reduction in oxygen flux was also demonstrated with films of PP, LLDPE, PET, and nylon 6,6 infused with Pd nanoparticles. This oxygen‐scavenging effect became more pronounced at lower oxygen concentrations. The catalytic role of Pd in the reaction of O₂ and H₂ and the enormous surface area provided by the dispersed nanoparticles were responsible for this highly efficient oxygen‐scavenging effect. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 749–756, 2004     

Studies on Micellar Behavior of PEO‐PBO or PEO‐PBO‐PEO Copolymers,or Surface Active Amphiphilic Ionic Liquids in Aqueous Media and Exploration of the Micellar Solutions for Solubilization of Dexamethasone and its Delayed Release

The aggregation behavior of a di‐ and tri‐block copolymers of type PEO‐PBO, PEO‐PBO‐PEO, surface‐active ionic liquid (SAIL) of type 4‐dodecyl‐4‐methylmorpholinium chloride [C₁₂mmor][Cl], and 1‐dodecyl‐1‐methylpyrrolidinium chloride [C₁₂mpyrr][Cl]) in water as well as in 10 mM of a poorly water soluble dexamethasone (dex) aqueous solution was studied by determining the critical micelle concentrations using drug solubilization, surface tension, and isothermal titration calorimetry (ITC) methods. ITC measurements were also made on solutions prepared by mixing the micellar aqueous solutions of copolymers and simple aqueous solutions of SAIL across the mole fractions at three different temperatures (298.15, 308.15, and 318.15 K). The thermodynamic parameters, namely Gibbs free energy (ΔG_m), enthalpy (ΔH_m), and entropy (ΔS_m), of micellization were calculated, and it was observed that the negative ΔG_m and positive ΔS_m for the mixture solutions increase with the increase in mole fraction of SAIL. Otherwise, the micellization is reported to be a spontaneous and highly entropy‐driven process. The dex‐solubilized micellar solutions were mixed with agar to obtain standing gels. The gel samples were dry‐cast into thin films, and the release of dex from films by simple dilution was monitored by UV measurements. The drug release data was fitted to several mechanistic models, and it was inferred that the release mechanism for dex from thin films is non‐Fickian for mixtures and Fickian in copolymer or SAIL micellar aqueous solutions. The transport of dex is diffusion‐controlled with diffusivities of 5.8–12 × 10^?11 m² s^?1 for copolymer micelles, 5–11 × 10^?11 m² s^?1 for micelles of SAIL, and 3–14 × 10^?11 m² s^?1 for the mixed micelles of copolymer and SAIL in aqueous media.     

Physicochemical studies of globular proteins—Bovine serum albumin,egg albumin,and lysozyme—In some aqueous iodide salts solutions of IA group and cetyltrimethyl ammonium bromide systems

Densities (ρ, kg m^?3), and viscosities (η, 0.1 kg m^?1 s^?1) of Bovine Serum Albumin (BSA), Egg Albumin, and Lysozyme in aqueous iodide salts of lithium, sodium, and potassium, along with cationic surfactant‐cetyltrimethyl ammonium bromide (CTAB) were measured at a temperature of 303.15 K. The 0.0010–0.0018 g %, w/v of each protein at an interval of 0.0002 mol L^?1 in 0.2, 0.4, and 0.8 millimol L^?1 of salt and CTAB are studied. Data are used for apparent molar volumes (V_?, 10^?6 m³ mol^?1) and intrinsic viscosities ([η], dL kg^?1), respectively. Data are regressed and extrapolated to zero concentrations for ρ⁰, η⁰, and limiting values and S_d, S_η and S_V corresponding slopes for protein–salt structural interactions. With size of cations, the densities decrease as CTAB > LiI > NaI > KI and increase with salts concentrations, with salts the densities are as Lysozyme > BSA > Egg Albumin, viscosities and V_? as BSA > Egg–Albumin > Lysozyme. The ρ and η values with CTAB higher and [η] are lower and converse at around 0.4 mmol L^?1 salt and is effective for greater stability of proteins. The [η] in CTAB are higher than other salts and decreases with size of cations with stronger intermolecular forces. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Reactive flash sintering and electrical transport properties of high-entropy (MgCoNiCuZn)1-xLixO oxides

In this paper, high-entropy (MgCoNiCuZn)_1-xLi_xO oxides (x = 0, 0.1, 0.15, 0.2, and 0.3) were synthesized via reactive flash sintering (RFS), and the effect of RFS process on the microstructure and electrical property of the materials were studied. The Li-doped materials exhibited a mixed ionic–electronic transport behavior. The oxidation of Co²⁺ into Co³⁺ upon Li incorporation into the materials synthesized via the conventional solid-state reaction route was not evidenced in the flash sintered materials. Instead, the charge unbalance in the Li-doped materials synthesized via RFS was compensated by oxygen vacancies and holes in the valence band of the oxides, which were accounted for the ionic conduction and electronic conduction, respectively. The ionic conductivity increased upon increasing the Li concentration as more oxygen vacancies were formed. The attraction between defects with different charges (Li_M^/ and V_O^••), which formed defect complexes, led to a decrease in the mobility of the defects, thus resulting in a less pronounced increase in the ionic conductivity at high Li concentrations. The change in the charge compensation mechanism of the materials indicates that the microstructure of such kind of oxides could be altered through RFS, and thus the property may be manipulated.     

Influence of surfactants on porous properties of carbon cryogels prepared by sol–gel polycondensation of resorcinol and formaldehyde

The role of surfactants on carbon cryogels is investigated by using three different surfactants, nonionic (SPAN80), cationic (trimethylstearylammonium chloride; C18) and nonionic polymeric fluorinated (FC4430) surfactants. By using different SPAN80 concentrations (10.0, 5.0, 2.5, 1.0 and 0.5 vol.%), double-structure carbon microspheres with S_BET (630–700 m²/g) and V_mes (0.51–0.93 cm³/g) are obtained. Mesoporous carbon cryogels with different S_BET and V_mes are prepared by using C18 with different volume ratios of cyclohexane to water in a C18/water/cyclohexane mixture. Carbon cryogels with S_BET (690–810 m²/g) and V_mes (0.83–1.74 cm³/g) are obtained when cyclohexane is contained in the mixture, on the contrary, when there is no cyclohexane in the mixture, a water-based carbon cryogel with low S_BET (480 m²/g) and V_mes (0.29 cm³/g) is obtained. Carbon cryogels prepared by using C18 have larger mesopore size and broader mesopore size distribution compared with carbon cryogels prepared by using other surfactants. Microcellular (sponge-like) carbon cryogels with mesoporous surface, S_BET (210–660 m²/g) and V_mes (0.37–0.92 cm³/g), are obtained by introducing FC4430 (two concentrations) to two starting RF solutions (C/W=6,45). Low FC4430 concentration leads to carbon cryogels with higher S_BET (610 and 660 m²/g) and narrower mesopore size distributions compared to the high concentration counterpart. Hence, it is found that different surfactant types have interesting effects on morphologies and porous properties of RF carbon cryogels.     

CFD Modeling of a Bubble Column Reactor Carrying out a Consecutive A → B → C Reaction

In this paper, we develop a CFD model for describing a bubble column reactor for carrying out a consecutive first‐order reaction sequence A → B → C. Three reactor configurations, all operating in the homogeneous bubbly regime, were investigated: (I) column diameter D_T = 0.1 m, column height H_T = 1.1 m, (II) D_T = 0.1 m, H_T = 2 m, and (III) D_T = 1 m, H_T = 5 m. Eulerian simulations were carried out for superficial gas velocities U_G in the range of 0.005–0.04 m/s, assuming cylindrical axisymmetry. Additionally, for configurations I and III fully three‐dimensional transient simulations were carried out for checking the assumption of cylindrical axisymmetry. For the 0.1 m diameter column (configuration I), 2‐D axisymmetric and 3‐D transient simulations yield nearly the same results for gas holdup ?_G, centerline liquid velocity V_L(0), conversion of A, χ_A, and selectivity to B, S_B. In sharp contrast, for the 1 m diameter column (configuration III), there are significant differences in the CFD predictions of ?_G, V_L(0), χ_A, and S_B using 2‐D and 3‐D simulations; the 2‐D strategies tend to exaggerate V_L(0), and underpredict ?_G, χ_A, and S_B. The transient 3‐D simulation results appear to be more realistic. The CFD simulation results for χ_A and S_B are also compared with a simple analytic model, often employed in practice, in which the gas phase is assumed to be in plug flow and the liquid phase is well mixed. For the smaller diameter columns (configurations I and II) the CFD simulation results for χ_A are in excellent agreement with the analytic model, but for the larger diameter column the analytic model is somewhat optimistic. There are two reasons for this deviation. Firstly, the gas phase is not in perfect plug flow and secondly, the liquid phase is not perfectly mixed. The computational results obtained in this paper demonstrate the power of CFD for predicting the performance of bubble column reactors. Of particular use is the ability of CFD to describe scale effects.     

Nonstoichiometry and Li‐ion transport in lithium zirconate: The role of oxygen vacancies

Understanding Li‐ion migration mechanisms and enhancing Li‐ion transport in Li₂ZrO₃ (LZO) is important to its role as solid absorbent for reversible CO₂ capture at elevated temperatures, as ceramic breeder in nuclear reactors, and as electrode coating in high‐voltage lithium‐ion batteries (LIBs). Although defect engineering is an effective way to tune the properties of ceramics, the defect structure of LZO is largely unknown. This study reports the defect structure and electrical properties of undoped LZO and a series of cation‐doped LZOs: (i) depending on their charge states, cation dopants can control the oxygen vacancy concentration in doped LZOs; (ii) the doped LZOs with higher oxygen vacancy concentrations exhibit better Li⁺ conductivity, and consequently faster high‐temperature CO₂ absorption. In fact, the Fe (II)‐doped LZO shows the highest Li‐ion conductivity reported for LZOs, reaching 3.3 mS/cm at ~300°C that is more than 1 order of magnitude higher than that of the undoped LZO.     

Preparation and properties of polyamide‐6‐based thermoplastic laminate composites by a novel in‐mold polymerization technique

In this work, a method for preparation of polyamide‐6 (PA6) based laminates reinforced by glass fiber‐ (GFL) or polyamide‐66 (PA66) textile structures (PL) via reactive injection molding is disclosed. It is based on in‐mold anionic polymerization of ε‐caprolactam carried out at 165°C in the presence of the respective reinforcements performed in newly developed prototype equipment whose design concept and operation are described. Both composite types were produced for reaction times of 20 min, with conversion degrees of 97–99%. Initial mechanical tests in tension of GFL samples displayed almost twofold increase of the Young's modulus and stress at break values when compared with the neat anionic PA6. The improvement was proportional to the volume fraction V_f of glass fiber fabric that was varied in the 0.16–0.25 range. A 300% growth of the impact strength was registered in PL composites with V_f of PA66 textile of 0.1. Removing the surface finish of the latter was found to be a factor for improving the adhesion at the matrix–fiber interface. The mechanical behavior of GFL and PL composites was discussed in conjunction with the morphology of the samples studied by optical and electron microscopy and the matrix crystalline structure as revealed by synchrotron X‐ray diffraction. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40083.     

Glass Formation and Characterization Studies in the TeO2–WO3–Na2O System

Glass formation behavior of the TeO₂–WO₃–Na₂O system was studied by using conventional melt‐quenching technique. A wide glass formation range was determined for the first time in the literature and thermal, physical, and structural characterization of sodium‐tungsten‐tellurite glasses were realized using differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy techniques. Glass transition (T_g) and crystallization (T_c/T_p) temperatures, glass stability (?T), density (ρ), molar volume (V_M), oxygen molar volume (V_O), and oxygen packing density (OPD) values and structural transformations in the glass network were investigated according to the equimolar substitution of TeO₂ by Na₂O+WO₃ and changing Na₂O or WO₃ at constant TeO₂.     

Characterization and electrical properties of methyl‐2‐hydroxyethyl cellulose doped with erbium nitrate salt

X‐ray diffraction, infrared (IR), and electrical properties for pure and Er (NO₃)₃‐doped methyl‐2‐hydroxyethyl cellulose (MHEC) with concentrations of 0.5, 1, 2, 5, 7, and 10 wt % were studied. X‐ray analysis indicates that the addition of Er (NO₃)₃, which is a crystalline material, to MHEC at concentrations 10 and 13 wt % leads to the formation of crystalline phases in the amorphous polymeric matrix. The appearance of the bending mode ν₂ and the combination mode (ν₁ + ν₄) of Er (NO₃)₃ in the IR spectra of composite samples indicates the coordination of nitro group in the chains of MHEC. From the I–V characteristics, it was found that the charge transport mechanism in MHEC appears to be essentially space charge limited conduction, while the predominant mechanism in the composite samples is Poole–Frenkel. Values of both drift mobility (μ) and the charge carrier density (n) has been reported. The temperature dependence conductivity data has been analyzed in terms of the Arrhenius and Mott's variable range hopping models. Different Mott's parameters such as the density of states, N(E_F), hopping distance (R), and average hopping energy (W) have been evaluated. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:2352–2361, 2006     

Improvement of enantioselectivity and stability of Klebsiella oxytoca hydrolase immobilized on Eupergit C 250L

BACKGROUND: A simple procedure was employed to covalently immobilize a Klebsiella oxytoca hydrolase (SNSM‐87) onto epoxy‐activated supports of Eupergit C 250L via multipoint covalent attachment. The resultant biocatalyst was explored for the hydrolytic resolution of a variety of (R,S)‐2‐hydroxycarboxylic acid ethyl esters. RESULTS: With the hydrolytic resolution of (R,S)‐ethyl mandelate in biphasic media as the model system, optimal conditions of 55 °C, pH 6 buffer and isooctane as the organic phase were selected for improving the enzyme stability (activity retained from 10% to 50% at 96 h) and enantioselectivity (V_SV_R^?1 value enhanced from 44 to 319) in comparison to the performance of free enzyme. Moreover, the immobilized enzyme retained its activity and enantioselectivity after eight cycles of hydrolysis at 55 °C. When applying the resolution process to other (R,S)‐2‐hydroxycarboxylic acid ethyl esters, 2.4‐ to 4.0‐fold enhancements of the enantioselectivity in general were obtainable. CONCLUSIONS: The enantioselectivity enhancement, good reusability and easy recovery after reaction indicate that the immobilized SNSM‐87 may have the potential as an industrial biocatalyst for the preparation of optically pure 2‐hydroxycarboxylic acids. Copyright © 2008 Society of Chemical Industry     

Design of gem‐Difluoro‐bis‐Tetrahydrofuran as P2 Ligand for HIV‐1 Protease Inhibitors to Improve Brain Penetration: Synthesis,X‐ray Studies,and Biological Evaluation

The structure‐based design, synthesis, biological evaluation, and X‐ray structural studies of fluorine‐containing HIV‐1 protease inhibitors are described. The synthesis of both enantiomers of the gem‐difluoro‐bis‐THF ligands was carried out in a stereoselective manner using a Reformatskii–Claisen reaction as the key step. Optically active ligands were converted into protease inhibitors. Two of these inhibitors, (3R,3aS,6aS)‐4,4‐difluorohexahydrofuro[2,3‐b]furan‐3‐yl(2S,3R)‐3‐hydroxy‐4‐((N‐isobutyl‐4‐methoxyphenyl)sulfonamido)‐1‐phenylbutan‐2‐yl) carbamate ( 3 ) and (3R,3aS,6aS)‐4,4‐difluorohexahydrofuro[2,3‐b]furan‐3‐yl(2S,3R)‐3‐hydroxy‐4‐((N‐isobutyl‐4‐aminophenyl)sulfonamido)phenylbutan‐2‐yl) carbamate ( 4 ), exhibited HIV‐1 protease inhibitory K_i values in the picomolar range. Both 3 and 4 showed very potent antiviral activity, with respective EC₅₀ values of 0.8 and 3.1 nM against the laboratory strain HIV‐1_LAI. The two inhibitors exhibited better lipophilicity profiles than darunavir, and also showed much improved blood–brain barrier permeability in an in vitro model. A high‐resolution X‐ray structure of inhibitor 4 in complex with HIV‐1 protease was determined, revealing that the fluorinated ligand makes extensive interactions with the S2 subsite of HIV‐1 protease, including hydrogen bonding interactions with the protease backbone atoms. Moreover, both fluorine atoms on the bis‐THF ligand formed strong interactions with the flap Gly 48 carbonyl oxygen atom.     

Structural interactions of globular proteins—Bovine serum albumin,egg albumin,and lysozyme,in aqueous medium,elucidated with molar volumes,viscosities, energy functions,and IR spectra from 293.15 to 303.15 K

Densities (ρ), apparent molar volumes (V_?), viscosities (η), and IR spectra on 0.0010–0.0018% aqueous solutions of bovine serum albumin (BSA), egg albumin (E‐Alb), and lysozyme at an interval of 0.0004% and at temperatures from 293.15, 298.15, and 303.15 K have obtained. The free energy (ΔG), entropy (ΔS), and enthalpy (ΔH) data with compositions and temperatures are calculated from the values of the flow velocity (v_f) of viscous flow, which decrease with temperature. The densities decrease with concentrations and temperatures except BSA, and the V_? values slightly increase with concentrations for BSA and lysozyme, which depict structural reorientations and transition states of protein molecules with increase in viscosities and decrease in reduce viscosities. The reduce viscosities at 293.15 K for BSA, E‐Alb, and lysozyme are noted positive, and for BSA and lysozyme remain positive at 298.15 and 303.15 K, whereas for E‐Alb it is negative. Activation energies (E*) for lysozyme remain almost constant, and are higher than those of the BSA and E‐Alb, respectively, also slightly higher E* values for the BSA than those of the E‐Alb at 293.15 and 298.15, and lower than of the E‐Alb at 303.15 K, are observed elucidating greater structural interactions for BSA at lower while weaker at temperatures. Stretching frequencies of amide (? NHCO? ), ? NH? , ? CO, and ? CH? groups of proteins are noted from IR spectra with broader stretching frequencies for ? NH? . © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1420–1429, 2007     

The Influence of Physical Properties of ZnO Films on the Efficiency of Planar ZnO/Perovskite/P3HT Solar Cell

ZnO thin films prepared by pulsed laser deposition at low temperature are utilized as the electron transport layer in CH₃NH₃PbI_3?xCl_x‐based perovskite solar cells with a planar heterojunction structure. Oxygen pressure greatly influences the transparent and conductive properties of ZnO films, which are extremely important as electron transport layer for the perovskite solar cells. The transparent and conductive properties of the films under different oxygen pressures are studied by ultraviolet‐visible spectrophotometer and Hall effect measurement system. Through controlling the oxygen pressure, transparent ZnO films with high conductivity are grown and adopted as electron transport layer for planar perovskite solar cell with a power conversion efficiency of 6.3%. After further surface modification of ZnO electron transport layer with [6,6]‐phenyl‐C61‐butyric acid methyl ester, the efficiency of the planar solar cell increases to 7.5%.