Enhancing the thermal stability of silica-mineralized wood via layer-by-layer self-assembly

Journal of Thermal Analysis and Calorimetry - Employing a combination of a layer-by-layer self-assembly and sol gel methods, a negatively charged silica sol was successfully deposited into the cell...     

Enhancing the healing ability and charge transport thermal stability of a diketopyrrolopyrrole based conjugated polymer by incorporating coumarin groups in the side chains

In this paper, we present a new design strategy for healable polymeric semiconductors, which are demanding for the future flexible electronics, by incorporating coumarin groups in the polymer side chains. The selection of coumarin groups is based on the fact that photo-dimerization can occur to coumarins upon UV light irradiation, thus side chains of conjugated polymers with coumarins can be cross-linked. The photo-crosslinking of side chains has negligible effect on the thin film morphology and interchain packing order for the DPP-based conjugated polymer PDPP4T-DCM with coumarins in the side chains. However, the photo-crosslinking can facilitate the repair of the mechanically damaged thin film of PDPP4T-DCM and the recovery of the semiconducting properties. Additionally, the photo-crosslinking due to the coumarins in the side chains can lock thin film morphology and thus improve the thermal stability of charge transport.     

Enhancing the strength of granules and thermal stability of ammonium nitrate

The effect of sulfate ions on the physicochemical properties of ammonium nitrate with a dolomite additive was examined. Changes in the rate of the IV → III phase transition, granule strength, number of thermal cycles, and content of ammonium nitrate aerosol in air after the granulation tower were evaluated.     

Lab-on-chip methodologies for the study of transport in porous media: energy applications

We present a lab-on-chip approach to the study of multiphase transport in porous media. The applicability of microfluidics to biological and chemical analysis has motivated much development in lab-on-chip methodologies. Several of these methodologies are also well suited to the study of transport in porous media. We demonstrate the application of rapid prototyping of microfluidic networks with approximately 5000 channels, controllable wettability, and fluorescence-based analysis to the study of multiphase transport phenomena in porous media. The method is applied to measure the influence of wettability relative to network regularity, and to differentiate initial percolation patterns from active flow paths. Transport phenomena in porous media are of critical importance to many fields and particularly in many energy-related applications including liquid water transport in fuel cells, oil recovery, and CO(2) sequestration.     

纳通道的物质传输特性及应用

近年来,随着材料科学、微纳加工技术和微纳尺度物质传输理论的发展,纳通道技术得到了越来越多的研究和关注。纳通道包括生物纳通道和人工纳通道,其孔径通常为1～100 nm。在这一尺度下,通道表面与通道内物质之间的作用概率大大增强,使得纳通道表现出许多与宏观体系不同的物质传输特性,例如通道表面电荷与通道内离子之间的静电作用产生了离子选择性,通道内电化学势的不对称分布产生了离子整流特性,物质传输过程中占据通道产生了阻塞脉冲特性等。纳通道中的这些物质传输特性在传感、分离、能源等领域具有广泛应用,例如通过对纳通道进行功能化修饰可以实现门控离子传输;利用亚纳米尺度的通道可以实现单分子传感;利用通道与传输物质之间的相互作用可以实现离子、分子、纳米粒子的分离;利用纳通道的离子选择性可以在通道内实现电荷分离,将不同形式的能量(如光、热、压力、盐差等)高效转化为电能。纳通道技术是化学、材料科学、纳米技术等多学科的交叉集合,在解决生物、环境、能源等基本问题方面具有良好的前景。该文综述了近10年来与纳通道物质传输理论以及纳通道技术应用相关的前沿研究,梳理了纳通道技术的发展过程,并对其在各个领域的应用进行了总结与展...     

Water-based conditions for the microscale parallel synthesis of bicyclic lactams

We report efficient miniaturized conditions to prepare arrays of bicyclic lactams for screening. The nature of the solvent is usually an important factor of reactivity. At a small synthesis scale, when automated pipetting devices are required, physical properties of the solvent, such as surface tension and vapor pressure also become very important. After having shown that a complete evaporation of a solution of reagents in water or a mixture of ethanol and water yields the expected lactams, we exemplified the reaction and procedure with the preparation of a library of 80 members. Our synthesis scheme is validated for synthesis scales from 1 to 100 mg. Therefore, it can be used both to produce rapidly test samples for HTS as well as to prepare intermediates for the synthesis of more elaborated nature-inspired compounds.     

Hydrothermal stability of pelletized zeolite 13X for energy storage applications

Three samples of pelletized zeolite Na-13X from different industrial suppliers were hydrothermally treated in an open system for up to 3500 adsorption/desorption cycles. Before and after this aging procedure, the samples have been characterized by water uptake measurements, X-ray powder diffraction (XRD), Hg-porosimetry, N₂- and CO₂-adsorption and small-angle X-ray scattering (SAXS). Large differences in the degree of degradation were found between the different materials: The adsorbent with the best performance maintains 79% of its original water uptake capacity after 3500 cycles, whereas this value is reduced to 65% after only 1600 cycles in case of the most unstable sample. For all materials, the residual water adsorption capacity was found to be higher than it was to expect from XRD data. In addition to structural changes of the zeolite cages, Hg-porosimetry and SAXS reveal a modification of the sample morphology in the meso- and macropore range. CO₂ adsorption experiments evidence that as a result of the aging process mass transfer kinetics are slowed down significantly. These findings indicate that the influence of hydrothermal treatment on the water adsorption performance not only depends on the crystal structure of the actual adsorbent, but is indeed a result of a complex interplay with the system of larger pores. The crucial role of the binder material is underlined by the fact that the most stable sample was produced by a so-called binder-free method.     

Enhancing the stability of Ni Fe-layered double hydroxide nanosheet array for alkaline seawater oxidation by Ce doping

Electrocatalytic hydrogen production from seawater holds enormous promise for clean energy generation. Nevertheless, the direct electrolysis of seawater encounters significant challenges due to poor anodic stability caused by detrimental chlorine chemistry. Herein, we present our recent discovery that the incorporation of Ce into Ni Fe layered double hydroxide nanosheet array on Ni foam(Ce-Ni Fe LDH/NF)emerges as a robust electrocatalyst for seawater oxidation. During the seawater oxidation proc...     

Improvement of thermal stability of EPDM by radiation cross-linking for space applications

Journal of Thermal Analysis and Calorimetry - The investigation of radiation effects on ethylene–propylene–diene terpolymer (EPDM) loaded with trifunctional monomer (trimethylolpropane...     

Enhancing the stability and performance of a battery cathode using a non-aqueous electrolyte

For conductive polymers to be considered materials for energy storage, both their electroactivity and stability must be optimized. In this study, a non-aqueous electrolyte (0.2 M LiClO₄ in acetonitrile) was studied for its effect on the charge storage capacity and stability of two materials used in batteries developed in our laboratory, polypyrrole (pPy) and poly(3,4-ethylenedioxythiophene) (PEDOT) doped with 2,2′-azino-bis(3-ethylbenzothiaxoline-6-sulfonic acid (ABTS). The results are compared to the performance of these materials in an aqueous electrolyte (0.2 M HCl/aq). Loss of ABTS dopant was eliminated principally due to the low solubility of ABTS in acetonitrile, resulting in cathode materials with improved stability in terms of load cycling and performance.     

Enhancing the stability and biological functionalities of quantum dots via compact multifunctional ligands

We have designed and synthesized a series of modular ligands based on poly(ethylene glycol) (PEG) coupled with functional terminal groups to promote water-solubility and biocompatibility of quantum dots (QDs). Each ligand is comprised of three modules: a PEG single chain to promote hydrophilicity, a dihydrolipoic acid (DHLA) unit connected to one end of the PEG chain for strong anchoring onto the QD surface, and a potential biological functional group (biotin, carboxyl, and amine) at the other end of the PEG. Water-soluble QDs capped with these functional ligands were prepared via cap exchange with the native hydrophobic caps. Homogeneous QD solutions that are stable over extended periods of time and over a broad pH range were prepared. Surface binding assays and cellular internalization and imaging showed that QDs capped with DHLA-PEG-biotin strongly interacted with either NeutrAvidin immobilized on surfaces or streptavidin coupled to proteins which were subsequently taken up by live cells. EDC coupling in aqueous buffer solutions was also demonstrated using resonance energy transfer between DHLA-PEG-COOH-functionalized QDs and an amine-terminated dye. The new functional surface ligands described here provide not only stable and highly water-soluble QDs but also simple and easy access to various biological entities.     

Titania membrane preparation with chemical stability for very hash environments applications

The high-quality tubular titania MF membranes are successfully prepared by dip-coating techniques and systematically investigated with regard to their corrosive resistances. The experiments show that dispersants PAA and anatase powder were preferably employed to prepare desired suspensions with solid loading 10–15 wt.% and that suspensions properties significantly affect the final membranes quality. The titania MF membranes with pure water permeability 742.42 l m⁻² h⁻¹ bar⁻¹ and 0.1 μm pore diameter have been obtained using the prepared suspensions. The corrosion resistance of titania membranes exhibits that the anatase layers are more stable than the alumina supports in boiling corrosive medium and that the poor quality titania MF membranes become more deteriorated due to its top layer pore blockages and fouling layer formation, which provides a wide range of practical application fields in very hash environments with reliable data supports.     

A simple microscale method for determining the relative stereochemistry of statine units

A simple method to determine the relative stereochemistry of statine amino acids (gamma-amino-beta-hydroxyacids) by using (1)H NMR spectroscopy is described. Configurational assignment of statine units within complex natural products is possible without degradation or derivatization as the syn and anti diastereomers can be distinguished by using a combination of chemical shift and coupling constant information derived from the alpha-methylene ABX system. Seventy-three examples are provided, demonstrating the scope and limitations of the methodology. These examples range in complexity from simple statine units to cyclic depsipeptides, such as tamandarin B.     

Thermal and chemical stability of diphenylalanine peptide nanotubes: implications for nanotechnological applications

The diphenylalanine peptide, the core recognition motif of the beta-amyloid polypeptide, efficiently self-assembles into discrete, well-ordered nanotubes. Here, we describe the notable thermal and chemical stability of these tubular structures both in aqueous solution and under dry conditions. Scanning and transmission electron microscopy (SEM and TEM) as well as atomic force microscopy (AFM) revealed the stability of the nanotubes in aqueous solution at temperatures above the boiling point of water upon autoclave treatment. The nanotubes preserved their secondary structure at temperatures up to 90 degrees C, as shown by circular dichroism (CD) spectra. Cold field emission gun (CFEG) high-resolution scanning electron microscope (HRSEM) and thermogravimetric analysis (TGA) of the peptide nanotubes after dry heat revealed durability at higher temperature. It was shown that the thermal stability of diphenylalanine peptide nanotubes is significantly higher than that of a nonassembling dipeptide, dialanine. In addition to thermal stability, the peptide nanotubes were chemically stable in organic solvents such as ethanol, methanol, 2-propanol, acetone, and acetonitrile, as shown by SEM analysis. Moreover, the acetone environment enabled AFM imaging of the nanotubes in solution. The significant thermal and chemical stability of the peptide nanotubes demonstrated here points toward their possible use in conventional microelectronic and microelectromechanics processes and fabrication into functional nanotechnological devices.     

On the potential of microscale electrokinetic cascade devices

Phages used for phage therapy of multidrug resistant bacteria must be highly purified prior to use. There are limited purification approaches that are broadly applicable to many phage types. Electrokinetics has shown great potential to manipulate phages, but obstructions from the cell debris produced during phage propagation can severely diminish the capacity of an electrokinetic device to concentrate and purify phage samples. A multipart insulator-based electrokinetic device is proposed here to remove the larger, undesirable components of mixtures from phage preparations while transferring the freshly purified and concentrated sample to a second stage for downstream analysis. By combining the large debris prescreen and analysis stages in a streamlined system, this approach simultaneously reduces the impact of clogging and minimizes the sample loss observed during manual transferring of purified samples. Polystyrene particles were used to demonstrate a diminished sample loss of approximately one order of magnitude when using the cascade device as opposed to a manual transfer scheme. The purification and concentration of three different phage samples were demonstrated using the first stage of the cascade device as a prescreen. This design provides a simple method of purifying and concentrating valuable samples from a complex mixture that might impede separation capacity in a single channel.     

Metabolic stability of the nucleoside transport system of Novikoff rat hepatoma cells

Rates of transport of uridine and thymidine, estimated with a rapid sampling technique, did not change with culture age. Inhibition of cellular RNA and protein synthesis for periods up to 6 h, did not lead to a loss of nucleoside transport activity. Mild treatment of cell suspensions with trypsin or neuraminidase had no effect on the kinetics of thymidine transport. Thus we conclude, contrary to previous reports, that nucleoside transporters are metabolically stable and that the decreases in nucleoside uptake rates observed with decreased protein synthesis reflect loss of nucleoside kinase activities. These kinases (which have narrow substrate specificity) rather than the membrane-associated, transport apparatus (which has broad substrate specificity) are the most likely sites for regulation of nucleoside uptake.     

Enhanced transport properties and thermal stability of agro-based RO-membrane for desalination of brackish water

This present work focused on preparation of economic and high performance reverse osmosis membranes, characterized by high transport properties (salt rejection and flux) towards desalination of brackish water. In this respect cellulose acetate from sugar-cane bagasse (BCA) and polymethyl methacrylate (PMMA) wastes were used as the substrates of membrane. The function of PMMA for enhancing the performance of bagasse-based cellulose acetate RO-membranes was investigated at operating pressure 35.85 bar and feed temperature 25 °C. The effects of casting solution, percentage of polymer and treatment of polymer by alkali (HPMMA) on the performance of RO-membrane were discussed. The preferable composition (wt.%) of the 90% BCA and 10% HPMMA was achieved salt rejection 92.18% and flux 325.9 l h⁻¹ m⁻². High water purity was obtained by pre-passing the salted water through membrane made from dissolved bagasse (methylol cellulose) together with PMMA, instead of ion exchanger, followed by passing the accepted water through BCA–HPMMA membrane, whereas the salt rejection increased to 98%. Also, by this approach we obtained high thermal stability membrane compared to CA-RO-membrane. This data gives highlight on possibility of application such type of membrane with high temperature operation conditions.     

Enhancing the thermal stability of polythiophene:fullerene solar cells by decreasing effective polymer regioregularity

Regioregularity has been shown to be an important aspect for the properties of poly(3-hexylthiophene) both in the pristine material and in bulk heterojunction photovoltaics with the fullerene derivative PCBM. Here we present a straightforward method to adjust the effective regioregularity of poly(3-hexylthiophene) by introducing 3,4-dihexylthiophene into the polymer chain. By investigating bulk heterojunction morphology and photovoltaic performance upon annealing, we observe that polythiophene with 91% regioregularity maintains equivalent electronic properties but forms a more thermally stable interpenetrating network with PCBM than polythiophene with regioregularity >96%.     

Improvement of pour point and oxidative stability of synthetic ester basestocks for biolubricant applications

For environmental reasons, as well as the dwindling source of petroleum, a new class of environmentally acceptable and renewable biolubricants based on plant oils is available. Even though plant oils possess excellent lubricant-related properties, there are some concerns about using it as biolubricant base oil. In this study we present a series of structures derived from oleic acid to be used as synthetic biolubricant basestocks. Measuring of pour point (PP), flash point, viscosity index (VI), oxidation onset temperature (OT) and signal maximum temperature (SMT) was carried out for each compound. Furthermore, the friction and wear properties were measured using a high-frequency reciprocating rig (HFRR). The resulting product structures were confirmed by NMR and FTIR spectroscopic analysis. The results showed that ethylhexyl 9-(octanoyloxy)-10-(behenoxy)octadecanoate with behenyl mid-chain ester exhibited the most favorable low temperature performance (PP ?48 °C) and ethylhexyl 9-(octanoyloxy)-10-(octyloxy)octadecanoate octyl mid-chain ester exhibited higher oxidation stability (OT 142 °C) than the other synthetic ester oils. On the other hand, the highest ball wear scan diameter was obtained for ethylhexyl 9-(octanoyloxy)-10-(behenoxy)octadecanoate while the lowest value was obtained for 9-hydroxy-10-octyloxyoctadecanoic acid. Overall, it was concluded that these synthetic ester oils have potential in formulation of industrial fluids for different temperature applications.