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Electronic health records (EHRs) are health information of patients that are saved digitally in a network. Various opportunities to enhance patient care, performance measures in clinical practice and contribute to clinical research in the future are provided by EHRs. The schemes used to store EHRs have been very insecure in the present era of smart cities and homes. The data can be easily breached by hackers and unauthorized external parties. Also, the data is not accessible to patients and care providers. These schemes are unable to create a balance between data security and data accessibility. But blockchain can resolve these issues. Blockchain creates a ledger system that is immutable and allows the transactions to take place in a decentralized manner. The three main features of blockchain technology - Security, Decentralization, and Transparency make any application built using it secure and not accessible by unauthorized parties. The manipulation of data is almost impossible to do in a blockchain network. In this project, we propose a system to implement EHRs using blockchain technology and make EHRs more secure and private. The blockchain technology will keep control over access to information using its cryptographic techniques and decentralization. It will also maintain the balance between data privacy and data accessibility. Our main objective of this project is the framing of data privacy and security issues in electronic healthcare

An accurate two dimensional subthreshold modeling of Germanium based Dual Halo Gate stacked Triple Material Surrounding Gate (Ge-DH-GS-TM-SG) tunnel field effect transistor is proposed for the first time in this paper. The model is solved by Poisson's equation using parabolic approximation method. The developed model gives analytical expressions for surface potential, electric field, threshold voltage, drain current, trans conductance to drain current ratio, subthreshold current and subthreshold swing are used to evaluate the short channel effects. The subthreshold swing of the proposed Ge-DH-GS-TM-SG-TFET is compared with Silicon based Single Halo Triple Material Surrounding gate TFET(Si-SH-TM-SG-TFET)and Triple Material Surrounding Gate TFET(TM-SG TFET). It is noticable that the proposed device Ge-DH-GS-TM-SG-TFET structure provides. poor outflow current IOFF (10−15A/μm), and remarkable improvement in ON current. (10−5A/μm).Moreover, the ION/IOFF ratio is 108. The developed model results are validated through comparison with 3-D sentaurus TCAD simulator results.

The prototype of Fe doped Dual Material Gate AlGaN/AlN/GaN High Electron Mobility Transistors(HEMTs) developed by a Finite Difference Method(FDM) is addressed in this paper. The equations are illustrated in a way that the dual material gate disintegrates into two distinct single material gates by discreting one 2-D equation into two isolated equations. The boundary conditions conclude in the clubbed model of two 1D equations. The work functions of two metal gates, their length difference and applied drain voltage, the proposed model estimates the Channel potential, Electric field, Threshold voltage and Drain current. A momentous increase of the drain current is witnessed when the δ-doping is integrated in the AlN layer. These features are also validated by TCAD simulations.

A subthreshold analytical model for Dual Material Double Gate Junctionless Tunnel FET (DMDG JLTFET) is developed. To analyze the behavior of short channel device, relevant parameters such as surface potential, electric field, threshold voltage, drain current, transconductance-to-drain current ratio, subthreshold slope and subthreshold swing are extracted from the 2-D analytical solution of Poisson's equation. Relating DMDG JLTFET to Junctionless MOSFETs, the results show significant reduction of Short Channel Effects (SCEs) at the drain end. The analytical model for DMDG JLTFET is effective due to the combined supremacy of uniform doping in the channel, usage of high-K gate dielectric material and work function engineering in the gate metal. The results obtained from the analytical model are simulated and validated using 2-D Sentaurus TCAD device simulator.

In the recent times, the performance of MOSFET in the nanoscaled region attains improvisations through several alternative device structures. Amongst many advanced MOSFET structures, the Double Gate (DG) MOSFET is one such structure which mitigates short channel effects because of its excellent scalability. Among the various structures, FET- based biosensors have shown an accelerated growth recently. Even though many analytical models are available for the Dual Material DG (DMDG) MOSFET structures, this work endeavours to introduce an analytical modeling of nanocavity embedded DMDG structure for the first time. The expression for surface potential is obtained by solving the 2-D Poisson’s equation using a parabolic-potential approach. The threshold voltage is determined from the minimum surface potential model. Sensitivity is computed in terms of relative change in the threshold voltage and it is derived using the model. The influence of various device geometrical parameters like length and thickness of the nanocavity on the sensitivity has been investigated. Further, a comparison of the sensitivity of DG MOSFET and DMDG MOSFET has also been made and the derived results are validated against TCAD simulation results.

This paper presents an approximate solution of a 2D Poisson’s equation within the channel region for Double-Gate AlInSb/InSb High Electron Mobility Transistors (DGHEMTs), using variable separation technique. The proposed model is used to obtain the surface potential, electric field, threshold voltage and drain current of both tied and separated gate bias conditions for Double-Gate AlInSb/InSb HEMTs. The surface potential and electric field are derived for both effective conduction paths of front and back heterointerface by a simple analytical expression and an analytical solution is verified with sentarus TCAD device simulator.

The present study was designed to investigate the effect of partial deoxygenation of extender on sperm quality, lipid peroxidation (LPO) and reactive oxygen species (ROS) in buffalo (Bubalus bubalis) during cryopreservation of semen. Semen extender was prepared freshly and split into three sub-extenders [Extender I: control (non-deoxygenated), Extender II (partially deoxygenated by using LN2 flushing) and Extender III (partially deoxygenated mechanically by vacuum pump)]. Amounts of dissolved oxygen (DO) were determined in all the three extenders and also in post-thaw semen. Ejaculates with mass motility of ≥3+ and individual progressive motility of 70% or greater were collected from Murrah buffalo bulls and utilized in the study. Each semen sample was divided into Groups I (diluted with Extender I), II (diluted with Extender II) and III (diluted Extender III) with a maximum of 60 × 106 sperm/mL. French mini straws (0.25 mL) were filled with the extended semen samples, sealed with polyvinyl alcohol powder, kept for 3 h at 5 °C for equilibration and then stored in an automatic programmable freezer until the temperature of straws reached −145 °C followed by plunging the straws into liquid nitrogen (–196 °C). Semen samples were evaluated at pre-freeze and post-thaw stages for various variables [sperm motility, live sperm count, acrosomal integrity, hypo-osmotic swelling (HOS) response, LPO and ROS concentrations]. The mean DO was less (P

In this study, the Fourier Transform Infrared (FT-IR) and FT-Raman of (1S,2R)-2-amino-1-phenylpropan-1-ol (abbreviated as 2APPO) have been recorded in the regions 4000-100 cm− 1 and 4000–400 cm− 1, respectively. A complete assignment and analysis of the fundamental vibrational modes of the molecule were carried out. The observed fundamental modes have been compared with the harmonic vibrational frequencies computed using DFT (B3LYP) method by employing 6-31 ++G(d,p) basis set. The vibrational studies were interpreted in terms of potential energy distribution. This study is extended to the HOMO - LUMO analysis to calculate the HOMO and LUMO energy gap (Δ), Ionization potential (I), Electron Affinity (A), Global Hardness (η), Chemical Potential (μ), Global Electrophilicity (ω) and the calculated HOMO, LUMO energy reveals shows that the charge transfers occurring within the molecule. In the thermodynamic properties of the 2APPO compound have been calculated at different temperatures and the results reveal that the standard heat capacities (Cp,m), standard entropies (Sm) and standard enthalpy changes (Hm) increase with rise in temperature.

The E-commerce zone is crowded with many Internet users. Medical E-commerce has had significant growth in part because of a great deal of growth in the Indian E-commerce field. Medical E-commerce sites use cloud computing to guarantee a high quality of service anywhere and anytime in the world. For online access, the customer's expectations are very high. Medical E-commerce retailers are directed towards cloud service providers based on their quality of service. During online shopping, impatient customers may abandon a specific medical E-commerce shopping cart due to slow response. This is quite difficult to endure for a medical E-commerce firm. The research described herein observed the effect of shopping cart abandonment on medical E-commerce websites deployed in cloud computing. The impact of the idle virtual machine on customer impatience during medical E-commerce shopping was also studied. The ultimate aim of this study was to propose a stochastic queueing model and to yield results through probability generating functions. The results of the model may be highly useful for a medical E-commerce firm facing customer impatience, so as to design its service system to offer satisfactory quality of service. Keywords: Cloud computing, Queueing, Virtual machine, E-commerce, Cart abandonment, Quality of Service

The paper discusses the standard frameworks and conceptual system architecture suitable for cloud computing environment. The major focus of this paper is to provide a clear description to advanced security features that supports better access provision to the cloud data users. This is accomplished through extending the support for the properties such as confidentiality, integrity, security factors. This paper does not provide any description of cryptographic phases and cloud deployment models associated with system frame work establishment. It provides a clear description to integrity and security assurance over the outsourced data. It acts as a supporting factor to access control models defined in previous papers of the domain.

The cyber-physical system and modern technology are useful in various applications of the network. However, various types of bugs and vulnerabilities are also brought along with modern technologies. The attacks caused by vulnerabilities create huge losses, necessitating the need to detect these attacks. Although, considerable work has been done by the researchers so far, but novel attacks are yet to be detected. Existing schemes are suitable for denial of service (DOS) type of attack class. However, these schemes are not efficiently detecting other types of attack classes such as Probing, Remote to User (R2L) and User to Root (U2R). In view of this, a new intrusion detection scheme based on ensemble of discriminant classifiers is proposed in this paper. In ensemble of discriminant classifier method, weak learners are converted into strong learners. KDDcup99 dataset has been used in the proposed scheme for empirical evaluation. The results show that the proposed scheme is superior in detecting all types of attack classes by achieving 98.9% overall accuracy. Network security, Cyber-physical system, Intrusion detection, Ensemble methods, Discriminant classifier, Denial of service (DOS)

In this paper, 3-D device simulations are performed to analyze the variations of uniform and non-uniformly (Gaussian) doped junctionless FinFETs. The impact of Fin width (Fw), Fin height (Fh), Channel length (Lg) and Gate Oxide (tox) on drain current, ION/IOFF ratio, subthreshold swing, Drain Induced Barrier Lowering (DIBL) of Si based Bulk Junctionless FinFETs is investigated. The results shows that the ION = 183μA/μm, IOFF = 4.449 × 10−5 μA/μm, is achieved for non-uniformly doping when compared to uniform doping configurations with ION = 102 μA/μm, IOFF = 3.05 × 10−5 μA/μm of junctionless FinFETs. Furthermore, the results also shows that non-uniformly doped junctionless FinFETs with fin width of 6 nm exhibits better DIBL of 22.5 mV/V and Subthreshold swing of 62.04 mV/decade than the uniform doped junctionless FinFET with DIBL of 80 mv/V and Subthreshold swing of 67.62 mV/decade. Thus, the non-uniformly doped junctionless FinFETs can effectively improve the performance of Junctionless FinFETs. In addition, to reduce the leakage current in bulk FinFETs effect of Punch-through Stop (PTS) layer, bulk doping concentration and body bias variations are studied. Finally, the 6T-SRAM circuit was implemented for JL-FinFETs and the results suggest that Gaussian doping JL-FinFETs strengthens the applicability of SRAM in the memory design.

An organic crystal of 2-amino-5-bromobenzoic acid methyl ester [abbreviated at 2A5BrBAMe], single crystal, belongs to the amino acid group, were grown by the slow evaporation solution growth technique at room temperature. The grown crystal had been subjected to single-crystal X-ray diffraction technique and cell parameters of the crystal were determined. The quantitative analysis on the crystal had been carried out using Fourier transform infrared (FTIR) and Fourier transform Raman (FT-Raman) spectral measurements. The molecular structures, vibrational wave numbers were calculated using DFT (B3LYP) method with 6-311++G(d,p) basis set. The formation of the hydrogen bond was investigated using NBO calculations. The calculated HOMO and LUMO energies show that charge transfer occur within the molecule. The dipole moment (μ) and polarizability (α0), anisotropy polarizability (Δα) and first order hyperpolarizability (β0) of the molecule have been reported.

Cloud computing is emerging paradigm provides various IT related services. The security and privacy are two major factors that inhibits the growth of cloud computing. Security factors are reasons behind lesser number of real times and business related cloud applications compared to consumer related cloud application. Firstly, the pros and cons of different Attribute Based encryption methods are analysed. Secondly, a new encryption method based on Attribute Based Encryption (ABE) using hash functions, digital signature and asymmetric encryptions scheme has been proposed. Our proposed algorithm is simplified yet efficient algorithm that can implemented for cloud critical application.

The phase formation and magnetic behavior of SmCo 4 − x Fe x B ( x = 0, 0.25, 0.5, 0.75, 1 and 2) produced by melt spinning have been investigated. At x = 0, melt spinning resulted in the formation of the SmCo 4 B phase and an ultrahigh coercivity of 44 kOe at 300 K. Fe substitution resulted in the formation of an amorphous structure along with the Sm(Co,Fe) 4 B phase during melt spinning. A single Sm(Co,Fe) 4 B phase was observed after crystallization when x 4 B and Sm 2 (Co,Fe) 17 B y were observed when x ⩾ 1. Hysteresis loops at x x ⩾ 1. In the crystallized Fe-containing materials, an increase in both coercivity and magnetization with increasing Fe content was observed until x = 1. Initial magnetization curves revealed nucleation-controlled behavior at x x = 1 and x = 2. The average grain size for the annealed SmCo 4 − x Fe x B samples measured from TEM micrographs was 110 nm for both x = 0.5 and x = 1 and 90 nm for x = 2.

In the proposed work analytical modeling of single halo triple material surrounding gate (SH-TMSG) MOSFET is developed. The threshold voltage and subthreshold current has been derived using parabolic approximation method and the simulation results are analyzed. The threshold voltage roll off is reduced and it denotes the deterioration of short channel effects. The results of the analytical model are delineated and compared with MEDICI simulation results and it is well corroborated.

A 2D analytical model for transconductance, Sub-threshold current and Sub-threshold swing for Triple Material Surrounding Gate MOSFET (TMSG) is presented in this paper. Based on the solution of two dimensional Poisson equation, the physics based model of sub-threshold current of the device is derived. The model also includes the effect of gate oxide thickness and silicon thickness on the sub-threshold swing characteristics. Transconductance to drain current ratio of the triple material surrounding gate is calculated since it is a better criterion to access the performance of the device. The effectiveness of TMSG design was scrutinized by comparing with other triple material and dual material gate structures. Moreover the effect of technology parameter variations is also studied and proposed. This proposed model offers basic guidance for design of TMSG MOSFETs. The results of the analytical model are compared with the MEDICI simulation results thus providing validity of the proposed model.

Nanocrystalline titanium oxide (TiO 2 ) thin films were deposited on silicon (1 0 0) and quartz substrates at various oxygen partial pressures (1 × 10 −5 to 3.5 × 10 −1 mbar) with a substrate temperature of 973 K by pulsed laser deposition. The microstructural and optical properties were characterized using Grazing incidence X-ray diffraction, atomic force microscopy, UV–visible spectroscopy and photoluminescence. The X-ray diffraction studies indicated the formation of mixed phases (anatase and rutile) at higher oxygen partial pressures (3.5 × 10 −2 to 3.5 × 10 −1 mbar) and strong rutile phase at lower oxygen partial pressures (1 × 10 −5 to 3.5 × 10 −3 mbar). The atomic force microscopy studies showed the dense and uniform distribution of nanocrystallites. The root mean square surface roughness of the films increased with increasing oxygen partial pressures. The UV–visible studies showed that the bandgap of the films increased from 3.20 eV to 3.60 eV with the increase of oxygen partial pressures. The refractive index was found to decrease from 2.73 to 2.06 (at 550 nm) as the oxygen partial pressure increased from 1.5 × 10 −4 mbar to 3.5 × 10 −1 mbar. The photoluminescence peaks were fitted to Gaussian function and the bandgap was found to be in the range ∼3.28–3.40 eV for anatase and 2.98–3.13 eV for rutile phases with increasing oxygen partial pressure from 1 × 10 −5 to 3.5 × 10 −1 mbar.

A 2D analytical model for the triple material surrounding gate MOSFET (TMSG) is developed by solving the Poisson equation. In this structure, we use three gate materials of different work functions. The model includes analytical modeling of parameters like surface potential, Electric field distribution and threshold voltage using parabolic approximation method. The short channel effects in this structure are suppressed because of the perceivable step in the surface potential profile, which screens the drain potential. The small difference of voltage due to different gate material keeps uniform electric field along the channel, which in turn improves the carrier transport efficiency. Hence the reduction of short channel effects (SCEs) are studied by modeling the device. The results of the analytical model are compared with the MEDICI simulation results and it is well validated.

Magnetic nanoparticles smaller than similar to 15 nm in diameter and with high magnetocrystalline anisotropies K-1 >= 1 MJ m(-3) can be used as building blocks for next-generation permanent magnets. Advances in processing steps are discussed, such as self-assembly, alignment of the easy axes and appropriate nanostructuring that will enable the fabrication of densely packed nanopartide assemblies with improved permanent-magnet properties. This study also proposes an idealized nanocomposite structure for nanoparticle-based future permanent magnets with enhanced energy products. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Organic scintillation materials are very much useful in the area of nuclear experiments, medical diagnostics and therapy. In the present investigation, we have systematically analyzed the vertical Bridgman grown organic scintillation material of trans-stilbene which is annealed at different annealing temperatures. Remarkable changes have been observed on its structural and optical properties. High resolution X-ray diffraction (HRXRD) analysis shows noticeable difference for the annealed specimen than the as-grown crystal. The observed results exposed that the crystalline quality was drastically improved by the elimination of defects or low angle boundaries by post growth annealing technique. Its optical behavior has been examined by photoluminescence, Raman and IR analyses. Vickers microhardness measurement has been carried out and found that hardness values increases for the annealed trans-stilbene single crystals.

In this paper FPGA synthesis of SIRM Fuzzy processor in biomedical application is proposed. This paper aims to design and simulate a simple and robust SIRM fuzzy processor to classify the epilepsy risk level of diabetic patients with minimum number of fuzzy rules from cerebral blood flow and EEG signals. Four different types of fuzzy models are compared The better fuzzy system is identified based on the performance and quality value. The tuned SIRM fuzzy system with five rules is selected which has performance of 98.58% and quality value of 36.56. VLSI design and simulation of the tuned SIRM fuzzy system is undertaken. VLSI system is tested for the same 200 cases of known diabetic patients. The average performance obtained for VLSI system is 98.28. This result indicates that the VLSI simulation is closely fallows the original MATLAB derived fuzzy system.

The main objective of this work is to reduce the chemical oxygen demand (COD) and color of the effluent containing reactive textile dye by microbial method. Anaerobic digestion has the potential to break down complex refractory organic compounds so that they may be further degraded aerobically or to completely mineralize them. An anaerobic digestion technique was applied to synthetic reactive red 2 dye cotton textile effluent aiming at the dye degradation. Halophilic and halotolerant bacterial culture Halomonas variabilis and Halomonas glaciei were used for degradation in batch-mode static condition. The temperature was kept constant at 30°C using CO(2) incubator. Maximum degradation was achieved within 144 h of experimental run. Degradation studies were made by determining COD and biochemical oxygen demand (BOD). Statistical analysis showed that the BOD and COD reduction rate were optimal in the concentration of 1297 mg L(-1) for the time duration of nearly 100 h.

A uniaxial sulphamic acid single crystal having dimensions of 35 mm diameter and 150 mm length was grown. Employing slow evaporation technique sulphamic acid crystals of size 10×10×5 mm 3 were grown. Etching, microhardness, high-resolution X-ray diffraction, laser damage threshold, UV–visible, Thermogravimetric and differential thermal analysis were made on conventional and the Sankaranarayanan–Ramasamy method grown sulphamic acid crystals. Etching behaviour of the (1 0 0) plane of conventional and the Sankaranarayanan–Ramasamy method grown sulphamic acid crystals was investigated with different etchants. Vicker's microhardness test on the (1 0 0) plane confirmed the mechanical stability of the conventional and the Sankaranarayanan–Ramasamy method grown sulphamic acid crystals. High-resolution X-ray diffraction results show that the crystalline perfection of sulphamic acid single crystals grown by the Sankaranarayanan–Ramasamy method is extremely good compared to the conventional slow evaporation method grown sulphamic acid crystal. Thermogravimetric and differential thermal analysis was carried out to determine the thermal properties of the grown crystal.

Large diameter semi-organic l -lysine monohydrochloride dihydrate ( L -LMHCl) single crystal was grown using Sankaranarayanan–Ramasamy (SR) method. The solubility and the nucleation of the material for different temperatures have been studied. The metastable zone width for L-LMHCl has been investigated. The growth rate along 〈0 1¯ 1〉, 〈0 1 1¯〉, 〈0 1 1〉 and 〈1 0 0〉 orientations was studied. The effect of gravity driven concentration gradient on SR method was investigated. The grown crystal was characterized by transmission and dielectric studies.

Single crystals of potassium acid phthalate (KAP), a semi-organic compound, have been grown at an average growth rate of 4 mm/day from aqueous solution by using the uniaxial crystal growth method of Sankaranarayanan–Ramasamy (SR). Transparent, cylindrical KAP crystal of size 70 mm length and 15 mm diameter was grown. The grown crystals were characterized by etching and UV–vis NIR analysis. HRXRD analysis indicates that the crystalline perfection of SR method-grown KAP is good. The KAP crystals grown by SR method have 9% higher transmittance than conventional method-grown crystal. The microhardness test was carried out on the (0 1 0) face and a load-dependent hardness was observed. TG–DTA evaluated the thermal properties of the grown crystal. KAP was found to be thermally stable up to 290 °C. The dielectric constant and dielectric loss of the crystal were studied as function of frequency and temperature.

The growth and characterization of a new metal-organic crystal [CS (NH2)2]2 · CoCl2 is reported. The growth of single crystal of BTCoC was accomplished from solution by slow evaporation method. The grown crystals were characterized by powder and single crystal X-ray diffraction, FT-IR, UV–Vis. and TG/DTA. The crystal structure and the unit cell parameters were analyzed from the X-ray diffraction studies. BTCoC crystallizes in the tetragonal system with the space group P42/n. The FT-IR spectrum analysis has confirmed the functional group in the BTCoC. The thermal behaviour of the crystals has been investigated by TG/DTA analyses. BTCoC has good optical transmission in the entire visible region, which is an essential requirement for a nonlinear crystal.

An attempt was made to grow naphthalene single crystals doped with various concentrations, ranging from 0.01 to 0.07 mol% of 2,5-diphenyloxazole (PPO). The crystals were grown from melts by a self-seeding vertical Bridgman technique (SSVBT), in a transparent two-zone furnace. In the present work, a flat interface was maintained for all runs. The optimum crystal growth rates were observed as 1 mm/h for pure and 0.01 mol% PPO-doped naphthalene, 0.7 mm/h for 0.03 mol% and 0.5 mm/h for 0.05 and 0.07 mol%-doped naphthalene. The fluorescence studies were carried out and it reveals the possibility of making a crystal scintillator with PPO impurity.

In this paper, we report scintillation characterizations on anthracene-doped naphthalene (NA) crystal. Crystals of this scintillator have been grown using the Bridgman-growth process. The peak of NA crystal emission is at 425 nm. The luminescence intensity of the NA crystal is 3 times that of pure naphthalene crystal. Naphthalene when doped with anthracene has high light output and fast principal decay constant ( 137 Cs source), energy resolution of 18% (FWHM) has been recorded at room temperature for NA crystals coupled to a photomultiplier. The pulse height of NA is 10 times greater than the pure naphthalene crystal. The NA detector exhibited a good timing performance compared to trans -stilbene detector.

The potential organic nonlinear optical (NLO) materials of benzimidazole single crystals have been grown by vertical Bridgman technique by optimizing the growth conditions. The crystalline perfection has been studied by high resolution X-ray diffractometry (HRXRD). Due to thermal stresses induced during growth and post-growth cooling cycle, the grown crystals were found to have some internal structural very low angle and low angle grain boundaries. After thermal treatment (annealing with slow heating and cooling rates) the observed grain boundaries were found to annulled out and the crystalline perfection has been increased up to a large extent. The laser damage threshold measurement and second-harmonic generation (SHG) studies have been made on the benzimidazole single crystal using Q-switched Nd:YAG laser as a source. 13 C-NMR studies have been carried out to identify the carbon present in the grown crystal.

Single crystals of pure and thallium (Tl) doped cesium iodide (CsI) have been grown by melt growth (Bridgman) technique. The grown crystals were subjected to powder X-ray diffraction and high-resolution XRD analysis. The cut and polished crystals were characterized for luminescence studies. UV-visible transmission studies have been carried out on the grown crystal in the wavelength range 200–650 nm. From the transmission spectrum it was found that the cut off wavelength increases with increase in Tl concentration and the transmittance is about 70%. The 0.06 mol% of Tl doped CsI crystal shows a good energy resolution of 7.6%. The hardness decreases for increasing the doping concentration. Etching studies have been carried out on doped and undoped crystals using methanol and water as etchant.

Acenaphthene single crystals (with a diameter of 15 mm and length of 28 mm) were grown by Vertical Bridgman technique using double wall ampoules, at a growth rate of 1.5 mm/day. Powder X-ray diffraction studies were carried out to determine the lattice parameters for the grown crystals. The micro-Raman studies have been performed to identify the various vibrational group frequencies present in the crystal. The grown crystals were subjected to Vickers microhardness, etching and UV-vis. spectral studies. The crystals grown were tested for their performance as scintillators by the timing resolution setup using 60 Co with 511 keV γ -ray source.

High-quality single crystals of naphthalene have been grown using selective self-seeding vertical Bridgman technique (SSVBT). The grown crystals were subjected to proton NMR, FT-IR, FT-Raman and X-ray rocking studies. Fluorescence emission and fluorescence lifetime measurement have been carried out to estimate the quality of the grown crystals.

In the field of nonlinear optics (NLO), the organic materials are relatively new comers compared to inorganic materials. Benzimidazole is an organic material presenting high nonlinear optical behaviour especially for second harmonic generation. Single crystals of benzimidazole are grown from vertical bridgman technique (VBT) by optimizing the growth conditions. The grown single crystals have been subjected to various characterization studies such as thermal, optical and mechanical properties. The obtained results and summary are given.

Single crystals of p-terphenyl were grown using selective self-seeding vertical Bridgman technique (SSVBT). Powder X-ray diffraction studies were carried out and lattice parameters were calculated for the grown crystal. Microhardness studies on the grown crystal were carried out using Vickers microhardness tester to evaluate the mechanical hardness of the crystal. FT-IR and FT-Raman spectra were recorded to identify different vibrations of p-terphenyl molecule in the grown crystals. 1 H NMR spectral analysis was carried out to check the purity of the material of the grown crystals. The fluorescence spectra were recorded and the results are discussed.

The electro-optic and nonlinear optical crystals of benzimidazole have been successfully grown by vertical Bridgman technique by optimizing the growth conditions. The reproducibility of crystal growth has been tested and established. This is the first report for the growth of benzimidazole by melt technique. The crystal system was determined from the single crystal X-ray diffraction. The functional groups have been identified and confirmed by NMR and FTIR studies. The second harmonic generation was confirmed from the green emission of benzimidazole using Nd:YAG laser as a source.

A novel material 4-hydroxy-benzaldehyde-N-methyl-4-stilbazolium tosylate has been successfully synthesized. Good optical quality crystals were grown using solution growth technique. Powder and single-crystal X-ray studies have been carried out for grown crystals and lattice parameters have been identified. FTIR spectra were recorded to identify the various functional groups present in the crystal. NMR spectrum studies have also been done. The second harmonic generation test of the grown crystal has been carried out.

Nanocrystalline Cu 2 O thin films have been synthesized using an activated reactive evaporation technique. Structural and optical characterizations of these films have been carried out using: glancing angle X-ray diffractometer; Fourier transform infrared spectrometer; transmission electron microscope; and UV-VIS-NIR spectrophotometer. The nanocrystallite size in these films was varied by varying deposition parameters. Optical studies show a direct allowed transition and a shift in the optical absorption edge from the bulk value with nanocrystallite size and stoichiometry of these films. These results show that single phase nanocrystalline Cu 2 O thin films can be synthesized at a relatively low substrate temperature using the activated reactive evaporation technique. These studies indicate that nanocrystallinity results in the stability of cubic Cu 2 O phase in these films.

The effect of particle size distribution of CdS nanoparticles on the band-edge photoluminescence (PL) spectrum is investigated. The resulting inhomogeneously broadened lineshape is found to be asymmetric and depend on the width of particle size distribution. The calculated lineshape is fitted to the measured PL spectrum of 3.6 nm diameter CdS nanoparticles, which showed the band-edge PL peak around 3.00 eV and that due to recombination at defects at 2.56 eV. The parameters of the PL spectrum of a bulk CdS film are used as inputs for the fitting. The average particle size and the standard deviation of the size distribution are obtained from the analysis. The particle size estimated from the PL data is compared with that obtained from x-ray diffraction measurements.

In the present studies, CdxZn(1−xx)S nanoparticles have been prepared by chemical capping method. Optical absorption, X-ray diffraction and transmission electron microscopy studies have been carried out. Size of the nano particles have been calculated from the XRD and optical absorption data. These studies indicate towards a kinetically controlled growth of nano particles. The growth of the CdxZn(1−xx)S nano particles is also affected by the action of the capping agent.

Unidirectional bulk ferroelectric Tri glycine sulphate (TGS) single crystal of diameter 18 mm and length 150 mm was successfully grown by SR method. The grown TGS single crystal was characterized using etching, Vicker's microhardness, TG–DTA and UV–Vis analysis. The TGS crystals grown by SR method have higher hardness than conventional method grown crystals. Dislocation density (DD) is less in SR grown crystal compared to conventional method grown TGS crystals. The transmittance of SR grown TGS is 8% higher than that of the conventional grown crystal.

Potassium acid phthalate crystal 140 mm long and 20 mm diameter has been grown from aqueous solution using modified SR method setup. The modifications were mainly focused for growth from aqueous solution. The ring heater assembly was fixed at the top of the ampoule for large evaporation. The grown crystals were characterized by optical transmission by UV–Vis spectrometer and optical birefringence studies. The UV–Visible spectrum shows that the KAP crystal has good optical transmission which shows the transmission of ∼ 100% for 0.5 mm thickness and 83% for 2 mm thickness. The birefringence value is found to be 0.179 and it is in the order of calcite crystals.

Crystals of trans-stilbene were grown by vertical Bridgman Technique and tested by X-ray rocking analysis. Low angle grain boundaries were identified for some crystals and they were tested for the performance of scintillation time characteristics. Their performance is compared with grain boundary-free crystals.