Observations on a low-angle X-ray diffraction peak for AR-HP mesophase pitch

Using wide angle x-ray diffraction on AR-HP mesophase pitch, a diffraction peak was detected at approximately 7° (2Θ). The low-angle peak was reproducible using different diffractometers and different sample-to-detector distances, and was observed for all pitch samples irrespective of the flow history, but not for carbon fibers derived from the same precursor fibers. The interplanar 002 peak at ∼25° was observed at the equatorial position, whereas, the peak at 7° was in the meridional position, i.e., the peaks are nominally 90° apart in an azimuthal scan. This signifies that the low angle peak was due to diffraction from planes that are orthogonal to (002) planes. The 7° peak is equivalent to a d-spacing of 1.25 nm, which corresponds to the nominal lateral dimension of the mesogen molecules that constitute the mesophase pitch. A typical MALDI analysis showed predominance of molecular weights of ∼500 au. Edges of such a constituent of mesophase pitch molecules, which lead to a lateral ordered spacing of approximately 1.1 nm, can lead to a diffraction peak at approximately 7°.     

Optimisation of withered leaf moisture during the manufacture of black tea based upon theaflavins fractions

A study was conducted to see the effect of different moisture content of withered leaf on the activity of oxidative enzymes polyphenoloxidase (PPO) and peroxidase (PO) and on the formation of theaflavins (TFs) and thearubigins (TRs). Six commercially popular cultivars TV1, TV7, TV9, TV23, TV26 and T.3E/3 of Assam, India, were processed in four different moisture levels (72%, 70%, 68% and 65%). Significant reduction in PPO and PO enzymes, TFs, TRs and theaflavin digallate equivalent was observed with the decrease in moisture content of withered leaf. The TFs (0.83–5.4 mg g^?1) and TRs (23–107 mg g^?1) fractions were lowest at moisture level 65 ± 1%. Of the six cultivars studied, better quality of black tea was obtained for cultivar TV1, TV9 and TV23 at 70 ± 1% moisture content, while for TV7 and TV26, it was 68 ± 1%. Withered leaf moisture content should be carefully chosen to obtain the better quality tea from specific cultivar.     

Study of Optical Properties of Single and Double Layered Amorphous Silicon Nitride Films for Photovoltaics Applications

Silicon - This work focuses on the optical properties of single- and double-layer amorphous silicon nitride (a-SiNx:H) thin films of different stoichiometry relevant for photovoltaic applications...     

In vivo Structure-Activity Relationship of Dihydromethysticin in Reducing Nicotine-Derived Nitrosamine Ketone (NNK)-Induced Lung DNA Damage against Lung Carcinogenesis in A/J Mice

Lung cancer is the leading cause of cancer-related deaths and chemoprevention should be developed. We recently identified dihydromethysticin (DHM) as a promising candidate to prevent NNK-induced lung tumorigenesis. To probe its mechanisms and facilitate its future translation, we investigated the structure-activity relationship of DHM on NNK-induced DNA damage in A/J mice. Twenty DHM analogs were designed and synthesized. Their activity in reducing NNK-induced DNA damage in the target lung tissues was evaluated. The unnatural enantiomer of DHM was identified to be more potent than the natural enantiomer. The methylenedioxy functional moiety did not tolerate modifications while the other functional groups (the lactone ring and the ethyl linker) accommodated various modifications. Importantly, analogs of high structural similarity to DHM with distinct efficacy in reducing NNK-induced DNA damage have been identified. They will serve as chemical probes to elucidate the mechanisms of DHM in blocking NNK-induced lung carcinogenesis.     

Structural characterisation and coloration of ligno-cellulose and protein fibre-blended structures

This study investigates the structures produced by blending ligno-cellulosic (ramie fibre, Boehmeria nivea L.) and protein fibres (mulberry silk, Bombyx Mori) with dissimilar mechanical properties. Ramie fibre, used for blending, is a ligno-cellulosic fibre with very high tenacity but low elongation. On the other hand, silk (mulberry) fibre has lower tenacity with better elongation. Blended fibrous structures have shown satisfactory tensile strength and elongation, while other physical properties, such as coefficient of friction, brightness and flexural rigidity, have also been improved. Technical findings revealed that the coefficient of friction reduced from 0.79 to 0.48 and specific work of rupture improved from 2.3 to 3.43 mJ/tex after incorporation of silk in the ligno-cellulosic fibre strand. Blended yarn cross-sectional images showed that finer silk fibres came to the surface, whereas the comparatively coarser cellulose-based ramie fibre migrated to the core. Atomic force microscopy of the blend structure was examined to assess the roughness and uniformity of the surface. Fourier Transform–infrared spectroscopy analysis verified the presence of amide groups (associated with silk fibre) and glucose ring groups (associated with the cellulose of Ramie fibre) in the same graph. In addition, innovative techniques of simultaneous coloration of the developed blends are also proposed scientifically.     

Synthesis and properties of biophenol-furfural based bioresin for curing of styrene butadiene rubber

In the present work, biophenol and furfural-based resol resin was synthesized and utilized for the very first time to cure styrene butadiene rubber (SBR). The reaction was studied over a range of times, temperatures, pH, and furfural to biophenol ratios to fix the optimum conditions. Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy revealed the functional groups and chemical structure of the synthesized resin, respectively. An exothermic peak for the resin curing appeared at 143°C in the differential scanning calorimetry thermogram of the resin. Then, the biophenol-furfural resin was utilized for the curing of SBR. The synthesized resin increased the tensile strength of the raw rubber from 0.20 ± 0.01 MPa to 1.22 ± 0.10 MPa at 10 phr loading, and the crosslink density was 2.56 × 10⁻⁵ mol/mL. The activation energy for curing SBR containing 10 phr resin was 97 kJ/mol. The storage modulus of the resin-cured compound was improved. The glass transition temperature of the raw SBR was also shifted from −43.8 to −42.3°C when 10 phr resin was used for the curing. Hence, for the first time, this work reported the utilization of biophenol-biosourced furfural resin to cure rubbers.     

Hydrogen economy: hope or hype?

Clean Technologies and Environmental Policy -     

Application of novel pretreatment technologies for intensification of drying performance and quality attributes of food commodities: a review

Food Science and Biotechnology - Drying is an energy-intensive process that can be reduced by the application of pretreatment prior to drying to enhance mass transfer and minimize energy...     

Industrial decarbonization: A revolution ahead

Clean Technologies and Environmental Policy -     

Self-Healing and -Repair of Nanomechanical Damages in Lead Halide Perovskites

Recovery from damage in materials helps extend their useful lifetime and of devices that contain them. Given that the photodamages in HaP materials and based devices are shown to recover, the question arises if this also applies to mechanical damages, especially those that can occur at the nanometer scale, relevant also in view of efforts to develop flexible HaP-based devices. Here, this question is addressed by poking HaP single crystal surfaces with an atomic force microscope (AFM) tip under both ultra-high vacuum (UHV) and variably controlled ambient water vapor pressure conditions. Sequential in situ AFM scanning allowed real-time imaging of the morphological changes at the damaged sites. Using methylammonium (MA) and cesium (Cs) variants for A-site cations in lead bromide perovskites, the experiments show that nanomechanical damages on methylammonium lead bromide (MAPbBr₃) crystals heal an order of magnitude faster than Cs-based ones in UHV. However, surprisingly, under ≥40% RH conditions, cesium lead bromide (CsPbBr₃) shows MAPbBr₃-like fast healing kinetics. Direct evidence for ion solvation on CsPbBr₃ is presented, leading to the formation of a surface hydration layer. The results imply that moisture improves the ionic mobility of degradation components and leads to water-assisted improved healing, i.e., repair of nanomechanical damages in the HaPs.