The Reactivity of Porcine Pancreatic alpha-Amylase Towards Native,Defatted and Heat-moisture Treated Potato Starches Before and After Hydroxypropylation

Potato starch was defatted (hot 75% n-propanol) and heat-moisture treated (100°C, 30% moisture) for various time intervals. The results showed that the above treatments increased the susceptibility of potato starch granules (heat-moisture treated > defatted) towards hydrolysis by porcine pancreatic α-amylase. These differences can be accounted for by the structural changes that occur within the amorphous and crystalline regions of the starch granule during defatting and heat-moisture treatment. Native, defatted (7 h) and heat-moisture treated (100°C, 30% moisture, 16 h) potato starches were hydroxypropylated (to different levels of molar substitution [MS]) with propylene oxide (2 → 20 %). The results showed that the alkaline reagents (NaOH and Na₂SO₄) used during hydroxypropylation increased the susceptibility of the above starches (native > defatted > heat-moisture treated) towards hydrolysis by α-amylase. Addition of propylene oxide to alkali treated starches, further enhanced their susceptibility, towards α-amylase. However, granule susceptibility towards α-amylase did not increase exponentially with increase in MS. The extent of hydrolysis began to decrease at MS levels of 0.29 (native), 0.28 (heat-moisture treated) and 0,26 (defatted).     

Sub-20 nm laser ablation for lithographic dry development

Pattern collapse of small or high aspect ratio lines during traditional wet development is a major challenge for miniaturization in nanolithography. Here we report on a new dry process which combines high resolution resist exposure with selective laser ablation to achieve high resolution with high aspect ratios. Using a low power 532?nm laser, we dry develop a normally negative tone methyl acetoxy calix(6)arene in positive tone to reveal sub-20?nm half-pitch features in a ～100?nm film at aspect ratios unattainable with conventional development with ablation time of 1-2?s per laser pixel (～600?nm diameter spot). We also demonstrate superior negative tone wet development by combining electron beam exposure with subsequent laser exposure at a non-ablative threshold that requires far less electron beam exposure doses than traditional wet development.     

Fermentative biohydrogen production: Evaluation of net energy gain

Most dark fermentation (DF) studies had resorted to above-ambient temperatures to maximize hydrogen yield, without due consideration of the net energy gain. In this study, literature data on fermentative hydrogen production from glucose, sucrose, and organic wastes were compiled to evaluate the benefit of higher fermentation temperatures in terms of net energy gain. This evaluation showed that the improvement in hydrogen yield at higher temperatures is not justified as the net energy gain not only declined with increase of temperature, but also was mostly negative when the fermentation temperature exceeded 25 °C. To maximize the net energy gain of DF, the following two options for recovering additional energy from the end products and to determine the optimal fermentation temperature were evaluated: methane production via anaerobic digestion (AD); and direct electricity production via microbial fuel cells (MFC). Based on net energy gain, it is concluded that DF has to be operated at near-ambient temperatures for the net energy gain to be positive; and DF + MFC can result in higher net energy gain at any temperature than DF or DF + AD.     

Investigation of water quality in combined recycled water and stormwater systems

Integrated Urban Water Management (IUWM) approach is an important strategy for urban water utilities to improve water security and system resilience. This study proposes a novel approach to combine recycled water and stormwater. This novel mixing method of capturing and treating stormwater at various locations along the recycled water pipeline and injecting treated stormwater in to the recycled water pipe line is unknown to have been practiced anywhere in the world. Water quality control of combined water is a vital factor for the safe use, as mixing percentage of stormwater is decided based on availability. A method to determine the water quality before mixing is required. Therefore, this paper investigates the appropriateness of the mass balance method to compute combined water quality and proposes a guideline for water quality of combined water.     

Kinetics, mechanism, isotherm and thermodynamic analysis of adsorption of cadmium ions by surface-modified Strychnos potatorum seeds

The surface-modified Strychnos potatorum seeds (SMSP) were used as an effective low-cost adsorbent for the removal of cadmium ions from aqueous solution. SMSP was characterized by Fourier transform infrared spectroscopy and scanning electron microscopic analyses. The effect of operating variables such as solution pH, adsorbent dose, contact time, initial cadmium ions concentration and temperature on the removal of cadmium ions were studied in a batch mode adsorption operation. The optimum conditions for the adsorption of cadmium ions onto the SMSP were found to be: pH of 5.0, SMSP dose of 2 g/L, contact time of 30min, temperature of 30 °C for an initial cadmium ions concentration of 100 mg/L. Kinetic data were analyzed using the pseudo-first order and pseudo-second order kinetic equations, intraparticle diffusion model, Boyd kinetic model and shrinking core model. The characteristic parameters for each model have been estimated. Adsorption of cadmium ions onto the SMSP follows the pseudo-second order kinetic model. The rate-limiting steps in the adsorption process were found to be external and internal diffusion. Equilibrium data were well described by the Langmuir isotherm model than the Freundlich isotherm model, which yields a maximum monolayer adsorption capacity of 200 mg/g. Thermodynamic parameters such as standard free energy change, enthalpy change and entropy change were also estimated. The results show that the removal of cadmium ions by the SMSP was found to be spontaneous and exothermic.     

Vanadium oxide nanotube spherical clusters prepared on carbon fabrics for energy storage applications

Vanadium oxide nanotubes have shown great promise as electrode materials for energy storage devices. In this study, we report the synthesis of V(2)O(5) nanotube (VNT) clusters, which form densely packed radial arrangements of VNTs on high-surface-area carbon fiber fabrics (CF). This was achieved by coating the CF with V(2)O(5) by pulsed laser deposition (PLD). Hydrothermal treatment of the PLD films in the presence of excess intercalated V(2)O(5) results in formation of well-adhered VNT clusters on the CF. The densely packed VNTs have inner and outer diameters and interlayer distances of ~24, ~70, and ~2.4 nm, respectively. Coin cell type supercapacitors (CR2032) were assembled using VNT-CF as the anode material and electrochemical properties were evaluated.     

Physicochemical properties of bread dough and finished bread with added pectin fiber and phenolic antioxidants

Comparative studies were conducted in this paper to investigate the effects of added dietary fiber (DF) and/or phenolic antioxidants on the properties of bread dough and finished bread. Breads were developed in the absence (control bread), or presence of apple pectin and/or fruit phenolic extracts (treated breads), and subjected to quality evaluation (attributes including color, weight, and volume) and characterization of chemical and rheological properties. Chemical analyses revealed that breads with added phenolic extracts had greater antioxidant activity and higher extractable phenolic content, than control bread and the treated breads with added apple pectin(s). The measured antioxidant activity was mainly derived from the phenolics present in bread. Storage modulus G' (elasticity) and loss modulus G″ (viscocity) of the treated bread dough with added pectin(s) only were higher than those of control dough. The G' or G″ of the treated breads incorporated with a combination of a pectin and fruit phenolic extract depended on the type of phenolic extract (that is, apple and blackcurrant extracts behaved differently from kiwifruit extract). The G' and G″ at the final baking step were higher than those of other stages, indicating an increase in cross-linking among polymeric molecules and bread particles of high molecular weight. We conclude that the added pectin and/or phenolic extract had influenced bread dough cross-linking microstructure and bread properties through being involved in the interactions with bread components such as wheat proteins during dough development and bread baking. PRACTICAL APPLICATION: Dietary fibers and phytochemicals (including phenolic antioxidants) have long been recognized as the active nutrients responsible for the health benefits of fruit and vegetables to humans. Interest in incorporating bioactive ingredients such as dietary fiber and phenolic antioxidants into popular foods like bread has grown rapidly, due to the increased consumer health awareness. The added bioactive ingredients may or may not promote the development of bread dough. This paper reports the findings associated with the properties of the functional breads enhanced with apple pectin and apple, blackcurrant, and kiwifruit phenolic extracts. Results of this paper indicate that the success of the development of such functional breads is ultimately determined by the interactions among added bioactive ingredients and other bread components.     

Biotransformation of 3-nitro-4-hydroxybenzene arsonic acid (roxarsone) and release of inorganic arsenic by Clostridium species

The extensive use of 3-nitro-4-hydroxybenzene arsonic acid (roxarsone) in the production of broiler chickens can lead to increased soil arsenic concentration and arsenic contaminated dust. While roxarsone is the dominant arsenic species in fresh litter, inorganic As (V) predominates in composted litter. Microbial activity has been implicated as the cause, but neither the specific processes nor the organisms have been identified. Here we demonstrate the rapid biotransformation of roxarsone under anaerobic conditions by Clostridium species in chicken litter enrichments and a pure culture of a fresh water arsenate respiring species (Clostridium sp. strain OhILAs). The main products were 3-amino-4-hydroxybenzene arsonic acid and inorganic arsenic. Growth experiments and genomic analysis indicate strain OhILAs may use roxarsone as a terminal electron acceptor for anaerobic respiration. Electronic structure analysis suggests that the reducing equivalents should go to the nitro group, while liberation of inorganic arsenic from the intact benzene ring by cleaving the C-As bond is unlikely. Clostridium and Lactobacillus species are common in the chicken cecum and litter. Thus, the organic-rich manure and anaerobic conditions typically associated with composting provide the conditions necessary for the native microbial populations to transform the roxarsone in the litter releasing the more toxic inorganic arsenic.