A Scenario Based Impact Assessment of Trace Metals on Ecosystem of River Ganges Using Multivariate Analysis Coupled with Fuzzy Decision-Making Approach

The growing consciousness about the health risks associated with environmental pollutants has brought a major shift in global concern towards prevention of hazardous/trace metals discharge in water bodies. Majority of these trace metals gets accumulated in the body of aquatic lives, which are considered as potential indicators of hazardous content. This results in an ecological imbalance in the form of poisoning, diseases and even death of fish and other aquatic lives, and ultimately affect humans through food chain. Trace metals such as Cd, Cr, Cu, Mn, Ni, Pb and Zn originated from various industrial operations containing metallic solutions and agricultural practices, have been contributing significantly to cause aquatic pollution. The present study develops a novel approach of expressing sustainability of river’s ecosystem based on health of the fish by coupling fuzzy sensitivity analysis into multivariate analysis. A systematic methodology has been developed by generating monoplot, two dimensional biplot and rotated component matrix (using ‘Analyze it’ and ‘SPSS’ software), which can simultaneously identify critical trace metals and their industrial sources, critical sampling stations, and adversely affected fish species along with their interrelationships. A case study of assessing the impact of trace metals on the aquatic life of river Ganges, India has also been presented to demonstrate effectiveness of the model. The clusters pertaining to various water quality parameters have been identified using Principal Component Analysis (PCA) to determine actual sources of pollutants and their impact on aquatic life. The fuzzy sensitivity analysis reveals the cause-effect relationship of these critical parameters. The study suggests pollution control agencies to enforce appropriate regulations on the wastewater dischargers responsible for polluting river streams with a particular kind of trace metal(s).     

Direct Staudinger–Phosphonite Reaction Provides Methylphosphonamidates as Inhibitors of CE4 De‐N‐acetylases

De‐N‐acetylases of β‐(1→6)‐D ‐N‐acetylglucosamine polymers (PNAG) and β‐(1→4)‐D ‐N‐acetylglucosamine residues in peptidoglycan are attractive targets for antimicrobial agents. PNAG de‐N‐acetylases are necessary for biofilm formation in numerous pathogenic bacteria. Peptidoglycan de‐N‐acetylation facilitates bacterial evasion of innate immune defenses. To target these enzymes, transition‐state analogue inhibitors containing a methylphosphonamidate have been synthesized through a direct Staudinger–phosphonite reaction. The inhibitors were tested on purified PgaB, a PNAG de‐N‐acetylase from Escherichia coli, and PgdA, a peptidoglycan de‐N‐acetylase from Streptococcus pneumonia. Herein, we describe the most potent inhibitor of peptidoglycan de‐N‐acetylases reported to date (K_i=80 μM ). The minimal inhibition of PgaB observed provides insight into key structural and functional differences in these enzymes that will need to be considered during the development of future inhibitors.     

High Frequency Electronically Tunable Floating Memristor Emulators employing VDGA and Grounded Capacitor

This paper introduces novel electronically tunable floating and grounded memristor emulator circuits using voltage differencing gain amplifier and one capacitor. The decremental and incremental memristor emulators have been suggested for both floating as well as grounded type configurations. Decremental to incremental and incremental to decremental configurations of memristor emulators can be easily obtained. The fingerprint of memristor is the pinched hysteresis loops that are maintained for the significant range of frequencies from 5 kHz to 1 MHz. The proposed memristor emulator sustains its range of frequency for both grounded and floating configurations. The simulations have been done in Eldo simulation tool of Mentor Graphics using TSMC 0.18 µm complementary metal-oxide semiconductor (CMOS) technology parameters. The proposed electronically tunable memristor emulators are used to realize analog filters in view of performance verification.

     

Low temperature coefficient and low line sensitivity subthreshold curvature-compensated voltage reference

A high-order curvature-compensated subthreshold voltage reference is proposed in this paper. The proposed curvature-compensated voltage reference consists of two supply-independent first-order voltage references and a curvature compensation circuit. The supply-independent first-order voltage reference uses a negative feedback loop which improves the line sensitivity and eliminates the demand of operational amplifier, whereas the curvature compensation circuit provides high-order temperature-compensated output reference voltage. The proposed curvature-compensated voltage reference provides an output reference voltage of 118.54 mV with a temperature coefficient of 21.5 ppm/°C over a wide temperature range of −60°C to 120°C . The power supply rejection ratio and line sensitivity are observed as −68.64 dB (for the frequency range of 1 Hz to 100 Hz) and 0.035%/V (for the supply voltage varies from 0.85 V to 2.5 V), respectively. The values of output noise at the frequencies of 1 kHz and 10 kHz without using any capacitive filter are obtained as 179.13 nV/ √ Hz and 123.87 nV/ √ Hz , respectively.     

New grounded and floating memristor emulators using OTA and CDBA

In this paper, grounded and floating decremental/incremental memristor emulators have been proposed by using an operational transconductance amplifier (OTA), current differencing buffered amplifier (CDBA), and a grounded capacitor. The proposed memristor emulators are simpler in design over most of the realizations of memristor emulators available in the literature. The proposed configurations of grounded and floating decremental memristor emulators can be easily converted into grounded and floating incremental memristor emulators. The pinched hysteresis loops obtained from proposed memristor emulators are maintained up to 1-MHz frequency in both decremental and incremental configurations. Simulation results have been obtained using a Mentor Graphics Eldo simulation tool in 0.18-μm complementary metal-oxide semiconductor (CMOS) technology parameters. Analog filters have also been designed to verify the performance of proposed grounded and floating memristor emulators.     

Fringe filtering technique based on local signal reconstruction using noise subspace inflation

A noise filtering technique is proposed to filter the fringe pattern recorded in the optical measurement set-up. A single fringe pattern carrying the information on the measurand is treated as a data matrix which can either be complex or real valued. In the first approach, the noise filtering is performed pixel-wise in a windowed data segment generated around each pixel. The singular value decomposition of an enhanced form of this data segment is performed to extract the signal component from a noisy background. This enhancement of matrix has an effect of noise subspace inflation which accommodates maximum amount of noise. In another computationally efficient approach, the data matrix is divided into number of small-sized blocks and filtering is performed block-wise based on the similar noise subspace inflation method. The proposed method has an important ability to identify the spatially varying fringe density and regions of phase discontinuities. The performance of the proposed method is validated with numerical and experimental results.     

High Slew-Rate and Very-Low Output Resistance Class-AB Flipped Voltage Follower Cell for Low-Voltage Low-Power Analog Circuits

Wireless Personal Communications - A low output resistance and high slew rate class-AB flipped voltage follower (FVF) cell is presented in this paper. The proposed FVF cell consists of cascoding...     

A 2-D DNS investigation of extinction and reignition dynamics in nonpremixed flame–vortex interactions

Two-dimensional (2-D) DNS investigations of extinction and reignition dynamics during interactions of laminar nonpremixed flames with counterrotating vortex pairs are performed. The length and velocity scales chosen for the vortices are representative of those in the near fields of high-Reynolds-number jets such as those occurring in Diesel engines. The governing equations are solved with sixth-order spatial discretization and fourth-order time integration. Chemistry is modeled as an irreversible single-step reaction. Local extinction along the symmetry axis, followed by reignition, is observed. The extinction is characterized by strong unsteady effects, which are captured well by 1-D transient diffusion flamelet libraries, provided the time-history of the instantaneous scalar dissipation rate is taken into account. On the other hand, reignition is essentially a 2-D phenomenon involving flame–flame interactions, which are favored for smaller vortices and increasing flame curvature. The effects of unsteadiness and curvature on extinction and reignition are carefully assessed through parametric studies involving a range of vortex and flame characteristics. The interaction outcomes are summarized on Reynolds–Damköhler number (Re–Da) diagrams, which show the combined effects of unsteadiness and curvature on extinction and reignition. The implications of the observed interaction outcomes for turbulent combustion modeling in the near fields of jet diffusion flames are discussed.     

The development of nanocrystalline silicon for emerging microelectronic and nanoelectronic applications

Films consisting of nanometer-scale silicon crystals with narrow size distribution can be fabricated using a variety of techniques and are of technological interest for nonvolatile semiconductor memory applications. One fabrication technique based on the crystallization of thin amorphous silicon films also shows potential for large-scale production of single isolated nanocrystals for future single-electron transistor and memory applications. A review of the most promising nanocrystalline silicon fabrication techniques and a discussion of current research in the area of crystallized thin-film amorphous silicon are presented in this article. For more information, contact Christopher C. Striemer, University of Rochester, Department of Electrical and Computer Engineering, Computer Studies Bldg. Room 509, Rochester, NY 14627; e-mail striemer@ece.rochester.edu.