Performance improvement of flash memory using AlN as charge-trapping Layer

Potential of high-k dielectric films for future scaled charge storage non-volatile memory (NVM) device applications is discussed. To overcome the problems of charge loss encountered in conventional flash memories with silicon-nitride (Si₃N₄) films and polysilicon-oxide-nitride-oxide-silicon (SONOS) and nonuniformity issues in nanocrystal memories (NC), such as Si, Ge and metal, it is shown that the use of high-k dielectrics allows more aggressive scaling of the tunnel dielectric, smaller operating voltage, better endurance, and faster program/erase speeds. Charge-trapping characteristics of high-k AlN films with SiO₂ as a blocking oxide in p-Si/SiO₂/AlN/SiO₂/poly-silicon (SOHOS) memory structures have been investigated in detail. The experimental results of program/erase characteristics obtained as the functions of gate bias voltage and pulse width are presented.     

Mechanism of positive charge generation in the bulk of HfAlO/SiO2 stack

We have investigated electrical stress-induced positive charge buildup in a hafnium aluminate (HfAlO)/silicon dioxide (SiO₂) dielectric stack (equivalent oxide thickness = 2.63 nm) in metal–oxide–semiconductor (MOS) capacitor structures with negative bias on the TaN gate. Various mechanisms of positive charge generation in the dielectric have been theoretically studied. Although, anode hole injection (AHI) and valence band hole tunneling are energetically favorable in the stress voltage range studied, the measurement results can be best explained by the dispersive proton transport model.     

Sliding mode control of quadruple tank process

The process investigated herein is the quadruple tank system that is stable only within a limited zone of operating parameters. The process model has been developed from fundamentals and tuned with experimental data. A controller design based on feedback linearization has been tested on this process model. Coupling feedback linearization with sliding mode algorithm provides robust control of the process and performs far superior to conventional PI control. A PC based controller interfaced to the experimental quadruple tank experimental set up has been used to implement this algorithm and test its performance. Inserting a ‘boundary layer’ around the sliding surface reduced the ‘chattering’ associated with sliding mode control. The implemented controller provides robust control and excellent set point tracking.     

Implementation of an optical S-R flip-flop with polarization encoded light signal

A new method is proposed to implement an optical S-R flip-flop by polarization encoded light signal,necessary optical nonlinear material and half-wave plate.In this system the real time speed of operation can be achieved,and at the time of transmission the average power of a byte remains constant.This polarization encoded flip-flop can act as a memory cell.     

Tuning the size and optical properties in molecular nano/microcrystals: manifestation of hierarchical interactions

Intermolecular interactions, such as hydrogen bonding, dipolar and van der Waals, occurring in molecular crystals cover a range of magnitudes. As the crystal evolves from a relatively softer state in the nanoscopic size regime to a harder one in the microcrystalline and bulk solid state, the impact of the hierarchy of intermolecular interactions can be expected to emerge in a progressive fashion. The strongest interactions alone would be manifested at small sizes; as the crystal grows, the effect of the weaker ones will be added on, with the bulk crystals exhibiting the cumulative impact of the different interactions. We demonstrate this phenomenon through investigations of the solution, colloid, and solid state of a novel zwitterionic molecule based on the diaminodicyanoquinodimethane framework. A reprecipitation-digestion protocol is developed for the fabrication of nano/microcrystals of varying sizes. Microscopic and spectroscopic characterizations reveal tuning of the size and optical properties of this material. The optical absorption of the colloidal particles evolves with size towards that of the bulk solid, the emission showing a steady enhancement of intensity. Crystallographic investigations coupled with semiempirical computations provide a viable model to describe the range of observations in terms of the gradual accumulation of hierarchical intermolecular interactions.     

Arsenic and other elements in hair, nails, and skin-scales of arsenic victims in West Bengal, India

For the first time, biological tissues (hair, nails, and skin-scales) of arsenic victims from an arsenic affected area of West Bengal (WB), India were analyzed for trace elements. Analysis was carried out by inductively coupled plasma-mass spectrometry (ICP-MS) for 10 elements (As, Se, Hg, Zn, Pb, Ni, Cd, Mn, Cu, and Fe). A microwave digester was used for digestion of the tissue samples. To validate the method, certified reference materials--human hair (GBW 07601) and bovine muscle (CRM 8414)--were analyzed for all elements. The W test was used to study the normal/log normal distribution for each element in the tissue samples. For hair (n=44) and nails (n=33), all elements show log-normal distribution. For skin-scale samples (n=11), data are not sufficient to provide the information about the trend. Geometric mean, standard error, and range for each element were presented and compared with literature values for other populations. This study reveals the higher levels of toxic elements As, Mn, Pb, and Ni in the tissue samples compared with available values in the literature. The elevated levels of these toxic metals in the tissues may be due to exposure of these elements through drinking water and food. The correlations of Mn and Ni with other essential elements, e.g. Fe, Cu, Zn, suggest that Mn and Ni may substitute for those elements in hair, nails, and skin-scales. However, correlation represents the relation between two elements only and does not take into consideration of the presence of other elements. Principle component analysis was applied to explain the behavior among the elements present in hair and nails. This study reveals that in the arsenic-affected areas of WB, the concentrations of other toxic elements in drinking water and foodstuff should be monitored to evaluate the arsenic poisoning.     

Improving Structural Stability and Anticoagulant Activity of a Thrombin Binding Aptamer by Aromatic Modifications

The thrombin binding aptamer (TBA) is a 15-mer DNA oligonucleotide (5′-GGT TGG TGT GGT TGG-3′), that can form a stable intramolecular antiparallel chair-like G-quadruplex structure. This aptamer shows anticoagulant properties by interacting with one of the two anion binding sites of thrombin, namely the fibrinogen-recognition exosite. Here, we demonstrate that terminal modification of TBA with aromatic fragments such as coumarin, pyrene and perylene diimide (PDI), improves the G-quadruplex stability. The large aromatic surface of these dyes can π-π stack to the G-quadruplex or to each other, thereby stabilizing the aptamer. With respect to the original TBA, monoPDI-functionalized TBA exhibited the most remarkable improvement in melting temperature (ΔT_m≈+18 °C) and displayed enhanced anticoagulant activity.     

Bunch graph based dimensionality reduction using auto-encoder for character recognition

Sometimes a group of similar types of dimensions is also treated as nodes. However, these groups can be considered as bunch nodes which may contain several nodes. This paper also justifies the study on bunch graphs which introduced a concept of graphs, where bunch nodes are also allowed. The auto-encoder, a specific type of feedforward neural network generally applied for encoding data in an unsupervised learning methodology to achieve good performance and better-classified data. This kind of network is composed of an encoder and decoder. The encoder compresses the data to an extent or layer, and then from that central layer decoder starts reconstructing the original data. This paper also investigates the dimensionality reduction ability of auto-encoders for character recognition and manipulates the results to accomplish better handling side of auto-encoders. This paper also focuses on the abilities of auto-encoders to reduce noise in data along with dimensionality reduction, trying to interpret the difference between results generated using bunch graph cut techniques. The dataset associated with computing for implementation purposes has been taken from MNIST dataset. Mainly, the two-dimensional plots are used in this paper for comparing results generated associated with different parameters that help in recognizing the character as partial and non-partial separabilities.

     

Gold and Hairpin DNA Functionalization of Upconversion Nanocrystals for Imaging and In Vivo Drug Delivery

Although multifunctional upconversion imaging probes have recently attracted considerable interest in biomedical research, there are currently few methods for stabilizing these luminescent nanoprobes with oligonucleotides in biological systems. Herein, a method to robustly disperse upconversion nanoprobes in physiological buffers based on rational design and synthesis of nanoconjugates comprising hairpin‐DNA‐modified gold nanoparticles is presented. This approach imparts the upconversion nanoprobes with excellent biocompatibility and circumvents the problem of particle agglomeration. By combining single‐band anti‐Stokes near‐infrared emission and the photothermal effect mediated by the coupling of gold to upconversion nanoparticles, a simple, versatile nanoparticulate system for simultaneous deep‐tissue imaging and drug molecule release in vivo is demonstrated.     

Association between vitamin deficiency and metabolic disorders related to obesity

Inappropriate food behavior contributes to obesity and leads to vitamin deficiency. This review discusses the nutritional status of water- and fat-soluble vitamins in obese subjects. We verified that most vitamins are deficient in obese individuals, especially the fat-soluble vitamins, folic acid, vitamin B₁₂ and vitamin C. However, some vitamins have been less evaluated in cases of obesity. The adipose tissue is considered a metabolic and endocrine organ, which in excess leads to changes in body homeostasis, as well as vitamin deficiency which can aggravate the pathological state. Therefore, the evaluation of vitamin status is of fundamental importance in obese individuals.