Double layer microwave absorber based on Cu dispersed SiC composites

The present work has been focused on designing an efficient and cost-effective double layer microwave absorber in 8.2–12.4?GHz frequency range. For the same, Cu particles were dispersed in SiC to achieve enhanced microwave absorption by combining the excellent dielectric characteristics of SiC with highly conductive Cu. Cu dispersed SiC composites were prepared by dispersing various weight fractions of Cu particles in the SiC matrix using planetary ball mill. The Cu dispersion in SiC yielded excellent relative complex permittivity values translating into a decrease in the reflection loss (RL) values of dispersed composites as compared to the pristine counterpart. The minimum RL of ?17.18?dB has been observed for 2?wt% Cu dispersed SiC composite at 11.81?GHz with a thickness of 1.3?mm and bandwidth corresponding to ?10?dB is 1.77?GHz. Genetic algorithm approach has been implemented to design double layer microwave absorber to further enhance the microwave absorption of the prepared composites for realizing a cost-effective solution. The optimum double layer results show the RL of ?32.16?dB at 11.05?GHz with 1.67?mm total thickness and bandwidth corresponding to ?10?dB is 2.35?GHz.     

Analysis of the urine proteome in patients with pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) accounts for over 213?000 deaths worldwide each year, largely due to late diagnosis. One of the risk factors for the development of PDAC is chronic pancreatitis (CP); the intense desmoplastic reaction makes differentiation between the two conditions extremely difficult. In order to identify biomarkers for noninvasive diagnosis, we performed 2-D DIGE analysis of urine samples from healthy individuals and patients with PDAC and CP. Despite considerable intersample heterogeneity, a total of 127 statistically valid (p<0.05), differentially expressed protein spots were detected, 101 of which were identified using MALDI-TOF MS. A number of these, including annexin A2, gelsolin and CD59 have already been associated with PDAC, however, their validation using immunoblotting proved challenging. This is probably due to extensive PTMs and processing thus indicating the need for raising specific antibodies for urinary proteins. Despite this, our study clearly demonstrates that urine is a valid source of noninvasive biomarkers in patients with pancreatic diseases.     

Identifying Seekers and Suppliers in Social Media Communities to Support Crisis Coordination

Effective crisis management has long relied on both the formal and informal response communities. Social media platforms such as Twitter increase the participation of the informal response community in crisis response. Yet, challenges remain in realizing the formal and informal response communities as a cooperative work system. We demonstrate a supportive technology that recognizes the existing capabilities of the informal response community to identify needs (seeker behavior) and provide resources (supplier behavior), using their own terminology. To facilitate awareness and the articulation of work in the formal response community, we present a technology that can bridge the differences in terminology and understanding of the task between the formal and informal response communities. This technology includes our previous work using domain-independent features of conversation to identify indications of coordination within the informal response community. In addition, it includes a domain-dependent analysis of message content (drawing from the ontology of the formal response community and patterns of language usage concerning the transfer of property) to annotate social media messages. The resulting repository of annotated messages is accessible through our social media analysis tool, Twitris. It allows recipients in the formal response community to sort on resource needs and availability along various dimensions including geography and time. Thus, computation indexes the original social media content and enables complex querying to identify contents, players, and locations. Evaluation of the computed annotations for seeker-supplier behavior with human judgment shows fair to moderate agreement. In addition to the potential benefits to the formal emergency response community regarding awareness of the observations and activities of the informal response community, the analysis serves as a point of reference for evaluating more computationally intensive efforts and characterizing the patterns of language behavior during a crisis.     

A 3.1–10.6 GHz UWB LNA Based on Self Cascode Technique for Improved Bandwidth and High Gain

In this work, we present a self cascode based ultra-wide band (UWB) low noise amplifier (LNA) with improved bandwidth and gain for 3.1–10.6 GHz wireless applications. The self cascode (SC) or split-length compensation technique is employed to improve the bandwidth and gain of the proposed LNA. The improvement in the bandwidth of SC based structure is around 1.22 GHz as compared to simple one. The significant enhancement in the characteristics of the introduced circuit is found without extra passive components. The SC based CS–CG structure in the proposed LNA uses the same DC current for operating first stage transistors. In the designed UWB LNA, a common source (CS) stage is used in the second stage to enhance the overall gain in the high frequency regime. With a standard 90 nm CMOS technology, the presented UWB LNA results in a gain \(\hbox {S}_{21}\) of \(20.10 \pm 1.65\,\hbox {dB}\) across the 3.1–10.6 GHz frequency range, and dissipating 11.52 mW power from a 1 V supply voltage. However, input reflection, \(\hbox {S}_{11}\), lies below \(-\,10\) dB from 4.9–9.1 GHz frequency. Moreover, the output reflection (\(\hbox {S}_{22}\)) and reverse isolation (\(\hbox {S}_{12}\)), is below \(-\,10\) and \(-\,48\) dB, respectively for the ultra-wide band region. Apart from this, the minimum noise figure (\(\hbox {NF}_{min}\)) value of the proposed UWB LNA exists in the range of 2.1–3 dB for 3.1–10.6 GHz frequency range with a a small variation of \(\pm \,0.45\,\hbox {dB}\) in its \(\hbox {NF}_{min}\) characteristics. Linearity of the designed LNA is analysed in terms of third order input intercept point (IIP3) whose value is \(-\,4.22\) dBm, when a two tone signal is applied at 6 GHz with a spacing of 10 MHz. The other important benefits of the proposed circuit are its group-delay variation and gain variation of \(\pm \,115\,\hbox {ps}\) and \(\pm \,1.65\,\hbox {dB}\), respectively.     

Room temperature synthesis of Li-doped MnO2 and its electrochemical activity

A new method was developed to synthesize a uniform round-shaped Li-doped MnO₂ by ozonation of acidic MnSO₄ in the presence of Li⁺ ions. X-ray diffraction study showed that the prepared compound was of a hexagonal-closed-packed (hcp) crystal structure with an average crystallite size of ~ 103 nm. The merging of 221/240 and 061/002 lines suggested a high microtwinning defect. Chemical composition has been explained in terms of Ruetschi's cation vacancy model. The electrochemical properties were studied by recording discharge profile in 9 M KOH at 1 mA/0.1 g and 100 Ω/0.5 g. The discharge proceeded with homogenous solid-state reduction into MnOOH followed by subsequent formation of Mn(OH)₂ via dissolution-precipitation mechanism.     

On Two Continuum Armed Bandit Problems in High Dimensions

We consider the problem of continuum armed bandits where the arms are indexed by a compact subset of \(\mathbb {R}^{d}\). For large d, it is well known that mere smoothness assumptions on the reward functions lead to regret bounds that suffer from the curse of dimensionality. A typical way to tackle this in the literature has been to make further assumptions on the structure of reward functions. In this work we assume the reward functions to be intrinsically of low dimension k ? d and consider two models: (i) The reward functions depend on only an unknown subset of k coordinate variables and, (ii) a generalization of (i) where the reward functions depend on an unknown k dimensional subspace of \(\mathbb {R}^{d}\). By placing suitable assumptions on the smoothness of the rewards we derive randomized algorithms for both problems that achieve nearly optimal regret bounds in terms of the number of rounds n.     

Recovery of lactic acid by batch reactive distillation

Lactic acid, being virtually a non‐boiling compound, is difficult to separate from its aqueous solution by conventional methods such as distillation. It is necessary to convert it to the relatively volatile ester and the separation of the ester, followed by hydrolysis, is recommended as an appropriate method of recovery. In the present work, we explore and investigate a novel reactive distillation strategy to perform esterification, distillation and hydrolysis in a single unit. The experiments were performed in a batch reactive distillation set‐up and the results have been explained with the help of an appropriate model. An unsteady state mathematical model based on an equilibrium stage concept was developed for batch reactive distillation. A pseudo‐homogeneous model was used for the determination of reaction kinetics. The effect of operating parameters such as feed concentration, mole ratio, catalyst loading, boil‐up rate, etc. on the recovery of lactic acid was studied with the help of simulation and experimental results. The feasibility issue of reactive distillation has been discussed based on the results obtained. Copyright © 2006 Society of Chemical Industry     

Influence of Inlet Premixing on Two-Phase Flow Patterns in a Horizontal Minichannel

Experimental investigations are reported for air–water two-phase flow through a 2.1-mm horizontal circular minichannel. Influence of inlet premixing on two-phase flow is established by constructing various T-junction geometries with cross-flow arrangement of air and water. Six different flow patterns are observed and flow pattern maps are developed. The developed flow pattern maps are then compared for different inlet designs. It is observed that the degree of premixing of the two fluids has significant effect on flow patterns, particularly for surface-tension-dominated regime. The results obtained from these experiments can provide guidelines for selection, design, and control of wide-ranging microfluidic applications. The flow pattern map established in the present study may facilitate prediction of flow regimes in pulsating heat pipes based on the inlet flow rates of the gas and liquid.