Dehydrogenation of Ammonia Borane with transition metal-doped Co–B alloy catalysts

The catalytic performance of transition metal-doped Co–B ternary alloys were tested for H₂ generation by hydrolysis of Ammonia Borane (AB). Chemical reduction method was used to dope Co–B catalyst with various transition metals, namely Cu, Cr, Mo, and W, using their corresponding metal salts. All transition metals induce significant promoting effects on the Co–B catalyst by increasing the H₂ generation rate by about 3–6 times as compared to the undoped catalyst. The effect of metal dopant concentration on overall catalyst structure, surface morphology, and catalytic efficiency were examined by varying the metal/(Co + metal) molar ratio. Characterizations such as XPS, XRD, SEM, BET surface area measurement, and particle size analysis were carried out to understand the promoting role of each dopant metal during AB hydrolysis. Dopant transition-metals, in either oxidized or/and metallic state, act as an atomic barrier to avoid Co–B particle agglomeration thus preserving the effective surface area. In addition, the oxidized species such as Cr³⁺, Mo⁴⁺, and W⁴⁺, act as Lewis acid sites to enhance the absorption of OH⁻ group to further assist the hydrolysis reaction over alloy catalysts. The promoting nature of transition metal dopants in Co–B alloy powders is demonstrated by the evaluated low activation energy of the rate limiting step and high H₂ generation rate (2460 ml H₂ min⁻¹ (g of catalyst)⁻¹ for Co–Mo–B) in the hydrolysis of AB.     

Detection of Adulterants and Contaminants in Liquid Foods—A Review

Milk and fruit juices have paramount importance in human diet. Increasing demand of these liquid foods has made them vulnerable to economic adulteration during processing and in supply chain. Adulterants are difficult to detect by consumers and thus necessitating the requirement of rapid, accurate and sensitive detection. The potential adulterants in milk and fruit juices and their limits set by different regulatory bodies have been briefly described in this review. Potential advantages and limitations of various techniques such as physicochemical methods, chromatography, immunoassays, molecular, electrical, spectroscopy with chemometrics, electronic nose, and biosensors have been described. Spectroscopy in combination with chemometrics has shown potential for rapid, precise, and sensitive detection of potential adulterants in these liquid foods.     

Passive Online Detection of 802.11 Traffic Using Sequential Hypothesis Testing with TCP ACK-Pairs

In this paper, we propose two online algorithms to detect 802.11 traffic from packet-header data collected passively at a monitoring point. These algorithms have a number of applications in real-time wireless LAN management, for instance, in detecting unauthorized access points and detecting/predicting performance degradations. Both algorithms use sequential hypothesis tests and exploit fundamental properties of the 802.11 CSMA/CA MAC protocol and the half-duplex nature of wireless channels. They differ in that one requires training sets, while the other does not. We have built a system for online wireless traffic detection using these algorithms and deployed it at a university gateway router. Extensive experiments have demonstrated the effectiveness of our approach: the algorithm that requires training provides rapid detection and is extremely accurate (the detection is mostly within 10 seconds, with very low false-positive and false-negative ratios), the algorithm that does not require training detects 60 percent to 76 percent of the wireless hosts without any false positives, and both algorithms are lightweight, with computation and storage overhead well within the capability of commodity equipment.     

FLOW CHARACTERISTICS OF SETTLING SUSPENSIONS AND FLUIDIZED BEDS OF SPHERICAL PARTICLES

The complete Navier-Stokes equations together with the free surface cell model have been solved numerically to obtain the theoretical estimates of drag coefficients of particle assemblages moving through an incompressible Newtonian liquid. The results reported herein have been expressed in terms of the constant rate sedimentation velocities for concentrated suspensions and voidage-velocity behaviour for particulately fluidized liquid-solid systems. Theoretical results have been validated by carrying out detailed comparisons with the widely used correlations available in the literature. Bearing in mind the experimental uncertainty in this field, the agreement between theory and experiments is satisfactory in the range of variables, (0.3 ≤ ε ≤ 0.9) and (10^-3 ≤ Re ≤ 100), studied in this work.     

Status of pulse milling processes and technologies: A review

Pulses are essential component of the human diet in the underdeveloped and the developing countries. Pulse milling mainly focuses on complete removal of the hull with minimum generation of powder, broken, and in certain cases dehulled split formation. Physical and mechanical properties of different pulses are described and their role in dehulling is discussed in this review. The review discusses nature of gums that binds hull and cotyledons together and their effect on milling characteristics. Pitting operation is performed for all pulses prior to the pretreatment for better dehulling. Various pretreatment processes (soaking, edible oils, chemicals, enzymes, hydrothermal) developed to loosen the bond are examined for their dehulling efficacy from commercial application viewpoint. Dependence of dehulling characteristics of different pulses on size, shape, variety, grain hardness, and moisture content are discussed. Most of the machines developed for pulses dehulling in India are abrasion based emery-cylinder concave system. The studies done for optimization of different pretreatment process conditions are also reviewed. The losses taking place in the form of broken and powder during pulse milling are described. Methods for performance evaluation of the pulse dehulling system are reviewed and expressions are suggested for proper evaluation. This review gives complete overview of the processes and technological status of pulse milling in present context.     

Infants with a congenital anomaly and the concentration of Mo,As, Mn,Zn and Cu in the mother's milk

Thirty-one samples of mothers' milk were analysed by neutron activation analysis for the concentrations of Mo, As, Mn, Zn, Cu 1.5 to 3 months post-partum. Group I consisted of 6 mothers having infants with neonatal obstructive jaundice and exhibited lower mean values of Cu and Mn at 0.18 μg/g and 11.7 μg/g as compared with 16 control subjects with 0.34 μg/g Cu and 23.0 μg/g Mn; Mo levels were approximately twice as high (12.2 μg/g) as the control values (6.4 μg/g); Zn and As were grossly comparable. Group II consisted of 9 mothers who had delivered infants with either a congenital hydrocephalus (n = 7) or meningomyelocoele (n = 2), exhibited a mean Cu level of 0.27 μg/g, Zn 1.7 μg/g, Mn 25.3 μg/g and As 0.45 μg/g. These findings are discussed in the light of the patho-physiology of the congenital anomaly of the infant.     

An intelligent recommendation system using gaze and emotion detection

Recently, recommendation system has become popular in many e-commerce websites. It helps users by suggesting products which they could buy. Existing work till now uses past feedback of user, similarity of other users’ buying pattern, or a hybrid approach in which both type of information is used. But the pitfall of these approaches is that there is a need to collect and process huge amount of data for good recommendation. This paper is aimed at developing an efficient recommendation system by incorporating user’s emotion and interest to provide good recommendations. The proposed system does not require any of aforementioned data and works without the continuous and interminable attention of the user. In this framework, we capture user’s eye-gaze and facial expression while exploring websites through inexpensive, visible light “webcam”. The eye-gaze detection method uses pupil-center extraction of both eyes and calculates the reference point through a joint probability. The facial expression uses landmark points of face and analyzes the emotion of the user. Both methods work in approximate real time and the proposed framework thus provides intelligent recommendations on-the-fly without requirement of feedback and buying patterns of users.

     

Luminescent quantum dot-bioconjugates in immunoassays, FRET, biosensing, and imaging applications

Colloidal semiconductor nanocrystals (quantum dots, QDs), such as CdSe-ZnS core-shell, are highly luminescent and stable inorganic fluorophores that represent a promising alternative to organic dyes for a variety of biotechnological applications. They show size-tunable narrow photoluminescence spectra spanning nearly the full visible region of the optical spectrum for QDs with CdSe cores. We have developed several approaches to conjugate either one type or a combination of biologically distinct proteins to CdSe-ZnS core-shell QDs rendered water-soluble by surface ligation with dihydrolipoic acid (DHLA) groups. QD-protein conjugates prepared using these approaches were found to exhibit high specificity and stability in immunoassays and in Förster resonance energy transfer (FRET) assays as well as in prototype QD bioconjugate sensors. Tunable QD emission over a wide range of wavelengths permitted effective tuning of the degree of energy overlap between the QD donor and an acceptor dye, allowing control over the rate of FRET. Additionally, we have used these QD-bioconjugates in live cell labeling. These hybrid bioinorganic conjugates represent a promising tool for use in many biotechnological applications.     

Direct comparison between the NIST 10 V Conventional Josephson Voltage Standard and 2.5 V Programmable Josephson Voltage Standard

In the present paper, the intercomparison results of the NIST 10 V Conventional Josephson Voltage Standard (NIST10) and 2.5 V Programmable Josephson Voltage Standard (PJVS) Systems have been discussed. The two systems were directly intercompared at 1.018 V and 2.511 V from September 2006 to February 2007. The differences between the two systems (i.e. NIST10 — PJVS) at 1.018 V and 2.511 V were 0.21 nV and −0.95 nV respectively. The intercomparison results reveal that the noise of digital voltmeter (DVM) affects the measurement results significantly. Even with DVM of the same model, their noise rejection capability may be different when accuracy of a few nanovolt (nV) is required, although for Zener reference standard measurement, it is sufficient because the measurement uncertainty is dominated by the noise and non-linear drift of Zener reference standard.     

A new model for non-Gaussian random excitations

Very often one is called upon to model time series data which are clearly non-Gaussian, but which retain some aspects of a Gaussian process. In the present paper, a novel methodology which helps in modelling such data is presented. The method is essentially to express the process as a series with finite number of terms, wherein the first term is a Gaussian process with zero mean and unit standard deviation. Non-Gaussian higher order correction terms are added to this such that each succeeding term is orthogonal or uncorrelated with all the previous terms. The unknown coefficients in the series representation can be expressed in terms of the estimated moments of the data. Further the autocorrelation or PSD of the data can be exactly reproduced by the non-Gaussian model. The use of the proposed model is illustrated by considering the unevenness data of railway tracks. Application to response of systems under non-Gaussian excitation is also briefly discussed.