A new two-dimensional C-V model for prediction of maximum frequency of oscillation (fmax) of deep submicron AlGaN/GaN HEMT for microwave and millimeter wave applications

An analytical two-dimensional capacitance-voltage model for AlGaN/GaN high electron mobility transistor (HEMTs) is developed, which is valid from a linear to saturation region. The gate source and gate drain capacitances are calculated for 120 nm gate length including the effects of fringing field capacitances. We obtain a cut-off frequency (f_T) of 120 GHz and maximum frequency of oscillations (f_max) of 160 GHz. The model is very useful for microwave circuit design and analysis. Additionally, these devices allow a high operating voltage V_DS, which is demonstrated in the present analysis. These results show an excellent agreement when compared with the experimental data.     

Role of Flaxseed Meal Feeding for Different Durations in the Lipid Deposition and Meat Quality in Broiler Chickens

This study investigated the role of flaxseed meal (FSM), a rich terrestrial source of ω-3 fatty acids, in the alteration of the fatty acid profile and metabolism, health indices, physicochemical properties, and sensory quality of broiler chicken meat. The broiler chickens were fed 100 g FSM kg⁻¹ diet for different time periods (1, 2, 3, 4, and 5 weeks). The results revealed that 100 g FSM feeding in broiler chickens for at least 3 weeks increased (P < 0.01) the EPA, DHA, MUFA, PUFA, ω-3 PUFA, and ω-6 PUFA of broiler chicken meat with the corresponding decrease in palmitic acid, stearic acid, and SFA content. 100 g FSM feeding up to 3 weeks has increased the Δ⁹-desaturases (P < 0.05), thioesterase index (P < 0.01), and Δ⁵-desaturase + Δ⁶-desaturase activity (P < 0.01) along with an improvement in health indices (P < 0.01) of chicken meat. Similarly, a reduction in meat cholesterol and fat content of thigh meat (P < 0.01) was observed by feeding 100 g FSM for at least 3 weeks with no effect on the pH, color scores, and sensory evaluation of broiler chicken meat. The water-holding capacity (WHC) and extract release volume (ERV) decreased, whereas, drip loss of meat increased (P < 0.01) due to the feeding of 100 g FSM beyond 3 weeks. Thus, this study concluded that 100 g FSM feeding for 3 weeks in broiler chickens significantly improves the fatty acid profile, lipid metabolism, and health indices of meat, without compromising the physicochemical properties of broiler chicken meat.     

Apple pomace ultrafiltration sludge – A novel substrate for fungal bioproduction of citric acid: Optimisation studies

Ever-growing demand for citric acid (CA) and urgent need for alternative sources has served as a driving force for workers to search for novel and economical substrates. Submerged fermentation was conducted using apple (Malus domestica) pomace ultrafiltration sludge as an inexpensive substrate for CA bioproduction, using Aspergillus niger NRRL567. The crucial parameters, such as total suspended solids and inducer concentration, were optimised by response surface methodology for higher CA production. The optimal CA concentrations of 44.9 g/100 g and 37.9 g/100 g dry substrate were obtained with 25 g/l of initial total solids and 3% (v/v) methanol and 25 g/l of total solids and 3% (v/v) ethanol concentration, respectively, after the 144 h of fermentation. Results indicated that total solids concentration, and methanol as an inducer, were effective with respect to higher CA yield and also indicated the possibility of using apple pomace sludge as a potential substrate for economical production of CA.     

Photoelectrochemical properties of porous silicon based novel photoelectrodes

Porous silicon interfaces have been modified with nitrided TiO₂ (TiON) nanoparticles to develop highly efficient photoelectrodes. Photoelectrodes were prepared by impregnating the electrochemically prepared porous silicon microchannels with titanium oxynitride. Photocatalytic measurements were carried out on titanium oxynitride particles in water‐methanol mixture and the results showed a dependence on the nitrogen concentration. Among the photoelectrodes used for photocurrent measurements, porous silicon impregnated with TiO₂ nitrided at 600 °C showed maximum photocurrent increase after exposure to sunlight‐type radiation. The enhancement in photocurrent was one order more for the porous silicon/titanium oxynitride hetero‐structure than that of polished silicon/titanium oxynitride hetero‐structure. Photoelectrodes thus prepared were found to have stable performance for a period of six months. This observation promises the possibility of using porous silicon/titanium oxynitride hetero‐structures as efficient electrodes for photovoltaic cells. Copyright © 2010 John Wiley & Sons, Ltd.     

Interplay of reactive oxygen species (ROS) and tissue engineering: a review on clinical aspects of ROS-responsive biomaterials

Reactive oxygen species (ROS) refers to the reactive molecules and free radicals of oxygen generated as the by-products of aerobic respiration. Historically, ROS are known as stress markers that are linked to the response of immune cell against microbial invasion, but recent discoveries suggest their role as secondary messengers in signal transduction and cell cycle. Tissue engineering (TE) techniques have the capabilities to harness such properties of ROS for the effective regeneration of damaged tissues. TE employs stem cells and biomaterial matrix, to heal and regenerate injured tissue and organ. During regeneration, one of the constraints is the unavailability of oxygen as proper vasculature is absent at the injured site. This creates hypoxic conditions at the site of regeneration. Hence, effective response against the stresses like hypoxia spurs the regeneration process. Contrary, hyperoxic condition may increase the risk of ROS stress at the site. TE tries to overcome these limitations with the new class of biomaterials that can sense such stresses and respond accordingly. This review endeavors to explain the role of ROS in stem cell proliferation and differentiation, which is a key component in regeneration. This compilation also highlights the new class of biomaterials that can overcome the hypoxic conditions during tissue regeneration along with emphasis on the ROS-responsive biomaterials and their clinical applications. Incorporating these biomaterials in scaffolds development holds huge potential in tissue or organ regeneration and even in drug delivery.

Graphical abstract

     

Bulk and lattice thermal expansion in Ce1−xSrxO2−x (0.0≤x≤0.10)

In this communication, we report on the bulk and lattice thermal expansion studies on a number of compounds, within the homogeneity range of solid solutions, in a series with the general composition Ce_1−xSr_xO_2−x (0.0≤x≤0.10). The XRD pattern of each product was refined to determine the solid solubility of SrO into the lattice of CeO₂, and the homogeneity range. The composition with maximum solid solubility limit of SrO in CeO₂ lattice, under the slow cooled conditions, was delineated as Ce_0.91Sr_0.09O_1.91 (i.e. 9 mol.% of SrO). The bulk thermal expansion measurements from ambient to 1123 K, as investigated by a dilatometer, revealed that the _l (293 to 1123 K) values for the compositions within the homogeneity range increase from 11.58×10⁻⁶ to 12.13×10⁻⁶ K⁻¹ on increasing the Sr²⁺ content from 0 mol.% (i.e. CeO₂) to 9 mol.%, i.e. the upper solubility limit of SrO into the lattice of CeO₂. A similar trend was observed in the lattice thermal expansion coefficients _a (293 to 1473 K) as obtained by a high temperature-XRD.     

ADYTIA: Adaptive and Dynamic TCP Interface Architecture for heterogeneous networks

Due to the widespread popularity and usage of Internet of things (IoT)‐enabled devices, there is an exponential increase in the data traffic generated from these IoT devices. Most of these devices communicate with each other using heterogeneous links having constraints such as latency, throughput, and interference from concurrent transmissions. This results in an extra burden on the underlying communication infrastructure to manage the traffic within these constraints between source and destination. However, most of the existing applications use different Transmission Control Protocol (TCP) variants for traffic management between these devices and are dependent on the stage of the sender, irrespective of the application types and link characteristics. Each operating system (OS) has different TCP variant for all applications, irrespective of path characteristics. Hence, a single TCP variant cannot select the best suitable link, which results in degradation in throughput compared to the existing default. Moreover, it cannot use the full capacity of the available link for different applications and network links, especially in heterogeneous network such as IoT. To cope up with these challenges, in this paper, we propose an Adaptive and Dynamic TCP Interface Architecture (ADYTIA). ADYTIA allows the usage of different TCP variants based on application and link characteristics, irrespective of the physical links of the entire path. It allows the usage of different TCP variants based on their design principle across heterogeneous technologies, platforms, and applications. ADYTIA is implemented on NS‐2 and Linux kernel for real testbed experiments. Its ability to select the best suitable TCP variant results in 20% to 80% improvement in throughput compared with the existing default and single TCP variant on Linux and Windows.     

Mechanical and thermal behaviour of biodegradable composites based on polycaprolactone with pine cone particle

Polycaprolactone (PCL) was reinforced with natural fibres as they not only permit a substantial reduction of the material costs, but also play a role as reinforcement in mechanical properties. This work was focused on the estimation of mechanical and thermal behaviour based on PCL and Pine Cone particles (PCP) filler at different weight percentages (0, 5, 10, 15, 30 and 45 wt%). Tests results indicated considerable improvement in mechanical properties, corresponding to a gain in impact strength and % elongation of 6 and 9.2% at 15 wt% particle loading, respectively. Some decrease in thermal stability was observed for composites with increasing filler content where as composite at 15% PCP was not significantly affected. Lower melting and crystallization enthalpies and higher crystallinity values were obtained for bio-composites compared with neat PCL. Some decrease in thermal stability and increase in oxygen and water vapour barrier properties were also observed for composites with increasing filler content.