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.     

Corrosion behavior analyses of metallic membranes in hydrogen iodide environment for iodine-sulfur thermochemical cycle of hydrogen production

HI decomposition in Iodine-Sulfur (IS) thermochemical process for hydrogen production is one of the critical steps, which suffers from low equilibrium conversion as well as highly corrosive environment. Corrosion-resistant metal membrane reactor is proposed to be a process intensification tool, which can enable efficient HI decomposition by enhancing the equilibrium conversion value. Here we report corrosion resistance studies on tantalum, niobium and palladium membranes, along with their comparative evaluation. Thin layer each of tantalum, palladium and niobium was coated on tubular alumina support of length 250 mm and 10 mm OD using DC sputter deposition technique. Small pieces of the coated tubes were subject to immersion coupon tests in HI-water environment (57 wt% HI in water) at a temperature of 125–130 °C under reflux environment, and simulated HI decomposition environment at 450 °C. The unexposed and exposed cut pieces were analyzed using scanning electron microscope (SEM), energy dispersive X-ray (EDX) and secondary ion mass spectrometer (SIMS). The extent of leaching of metal into liquid HI was quantified using inductively coupled plasma-mass spectrometer (ICP-MS). Findings confirmed that tantalum is the most resistant membrane material in HI environment (liquid and gas) followed by niobium and palladium.     

Energy economics and environmental assessment of hybrid hydel-floating solar photovoltaic systems for cost-effective low-carbon clean energy generation

Clean Technologies and Environmental Policy - The simultaneous escalation in energy consumption and greenhouse gases in the environment drives power generation to pursue a more sustainable path....     

Producing asphaltene fibres from bitumen-derived asphaltenes for carbon fibre development: Part one–Electrospinning

Bitumen-derived asphaltenes are rich in carbon but of low value and contain other elements such as nitrogen, sulphur, oxygen, vanadium, and nickel. Their use as a feedstock for producing carbon fibre (CF) is largely under-investigated. In this study, electrospinning was used to create asphaltene fibres (AFs), which is a pre-carbon fibre material, from asphaltenes. Various operational parameters were investigated in order to improve the spinning abilities, such as the concentration of asphaltenes in toluene, pumping rate, voltage, and distance between the tip of the needle to the collector. Results indicated that asphaltenes concentrations had the greatest effect on the quality of the produced AFs, with the range of asphaltenes concentrations from 45 to 50 wt.% being suitable for producing the AFs, while voltage, pumping rate, and tip distance had less of an effect on electrospun AF production.     

Perspectives on Dielectric Modulated Biosensing in Silicon Tunnel FETs

Silicon - Consistent research on Tunnel Field Effect Transistors (TFETs) has led to the lookout for their viability in biosensing. The dependence of the tunneling probability on the gate dielectric...     

Little amounts of carbon nanotubes as anti-wear reinforcement for alumina in dry sliding

Carbon nanotubes (CNTs) are a leading choice for reinforcing oxide and nitride ceramics, but investigations into the tribological performance of CNT–ceramic composites remain inconclusive. Here, we show that reinforcement with only .1 wt% multi-walled CNTs improves the antifriction and anti-wear performance of zirconia-toughened alumina by up to 23% and 51%, respectively. Dry sliding tests under normal loads of 40–60 N for a sliding distance of 1000 m reveal a load-dependent transition in the lubrication mechanism—CNTs retain their tubular morphology at low loads and reduce friction via a sliding–rolling response, whereas high sliding loads trigger the formation of a uniform, thin lubricating film by the repeated crushing and smearing of exfoliated nanotubes. Raman spectra analyses confirmed that the carbon-rich tribo-film possesses a graphitic structure. Well-dispersed CNTs prevent wear loss by mechanisms, such as crack bridging and grain anchoring. The present work opens up new frontiers for the application of CNT–alumina tribo-ceramics in anti-wear, unlubricated, and high contact stress applications, such as in the manufacturing and mining industries.