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The present work has enabled to aspire the enhancement of palm biodiesel viability for compression ignition (CI) engine applications using reformulation strategy by the addition of higher alcohols. In this work, 20% and 30% of 1-decanol and n-hexanol were used for ternary blend preparation along with palm biodiesel concentration as 20–30% and 50% diesel fuels for combustion, emission, and performance behaviour investigation in CI engine. Furthermore, the experimental results were also compared with 100% palm biodiesel (P100) and pure diesel (D100) and a binary blend of D50B50 fuels. The experimental study has revealed that the presence of higher alcohols in the ternary blends has improved the cylinder pressure and heat release rate whereas the same trend was not evident in binary biodiesel blend. All the ternary blends of higher alcohols-biodiesel and diesels have shown higher brake thermal efficiency and reduction in brake-specific fuel consumption. At the same time, decanol and hexanol addition in the palm biodiesel-diesel blends has favoured in all exhaust emission reductions with slight exemption in NO emission. The experimental results are optimized through multivariate and desirability analyses for identifying the effective composition of blend. Multivariate analysis has revealed that the higher alcohol proposition in the ternary blend was more influential than the type of higher alcohol. Furthermore, the desirability study has also validated the prescribed proportion with the maximum error of 6.17% for D50P22DC28 and 4.84% for D50P26HE24. Finally, the research concludes that decanol would be the preferable choice for ternary blend preparation than hexanol due to its overall better performance. x

A new molecular adduct namely, 4-(dimethylamino)benzaldehyde 4-nitrophenol (4DMAB4NP), has been synthesized through crystal engineering route by reacting 4-(dimethylamino)benzaldehyde and 4-nitrophenol in equimolar ratio. This hydrogen bonded material is found to have crystallized with centrosymmetric space group of P21/c at room temperature (RT) and making it appropriate for third order nonlinear optical (TONLO) applications. The different kinds of functional groups existing in the 4DMAB4NP were recorded and assigned through FTIR and NMR spectral studies. Thermal behavior of 4DMAB4NP was analyzed through TGA and DTA analyses. Its solubility in toluene solvent was measured to obtain high quality single crystals. The 4DMAB4NP single crystals were characterized for their laser damage threshold, TONLO properties and optical limiting behavior. Further, the dielectric behavior of 4DMAB4NP single crystal were also investigated as a function of temperature (313–343 K). In addition, density functional studies of 4DMAB4NP molecule in gaseous phase were accomplished at the B3LYP/6–311++G (d, p) basis function. Finally, 3-D Hirshfeld surface maps and the 2-D fingerprint diagram were generated for the title molecule by using crystal explorer 3.1 program.

Isothermal solvent evaporation method was employed to grow Undeuterated Hydrazonium L-tartrate (HLT) single crystals using water:methanol (5:1) solution as a solvent. The proton and carbon positions of HLT have been revealed by 1H and 13C NMR spectrum, respectively. The energy emission behaviour of HLT were analysed by photoluminescence spectrum. The nonlinear refractive index (n2), nonlinear absorption coefficient (β) and third order nonlinear susceptibility (χ 3) of HLT single crystal were determined by adapting Z-scan technique. Quantum chemical calculations on HLT was carried out by DFT using B3LYP/6-311++G(d,p) basis set. The predicted first hyperpolarizability of HLT is found to be 1.09 times greater than that of urea and suggests that HLT could be an attractive material for NLO applications. The predicted HOMO-LUMO energies of HLT confirmed that charge transfers occur within the molecule. The molecular bond strength and stability of the title compound were analysed by employing NBO analysis. The other molecular properties such as Mulliken atomic charge, ESP map, thermodynamic functions and perturbation theory energy have also been investigated. These investigations have been carried out for the first time, to the best our knowledge, in order to study the nonlinear optical properties of HLT and to enhance its usefulness for NLO applications.

Nanorod films of cobalt oxide (Co3O4) have been grown by a unique oblique angle deposition (OAD) technique in an e-beam evaporator for supercapacitor electrode applications. This technique offers a non-chemical route to achieve large aspect ratio nanorods. The fabricated electrodes at OAD 80° exhibited a specific capacitance of 2875 F/g. The electrochemically active surface area was 1397 cm−2, estimated from the non-Faradaic capacitive current region. Peak energy and power densities obtained for Co3O4 nanorods were 57.7 Wh/Kg and 9.5 kW/kg, respectively. The Co3O4 nanorod electrode showed a good endurance of 2000 charge-discharge cycles with 62% retention. The OAD approach for fabricating supercapacitor nanostructured electrodes can be exploited for the fabrication of a broad range of metal oxide materials.

We report on the studies performed on Morpholinium 2-chloro-4-nitrobenzoate (M2C4N), a second order nonlinear optical (NLO) material, which has been proved to crystallize with chiral structure as compared to its other two variants. The synthesized powder was studied for its composition, crystalline phase and NLO efficiency and phasematchability. The solubility and the metastable zone width (MSZW) of the title compound were measured for the growth of bulk crystals of M2C4N. A smoky pattern observed in the middle region of the crystals that could prevent it from optical applications was greatly reduced, through suitable modifications in the growth process. The optical properties such as luminescence and laser damage threshold resistance were studied for the bulk crystals whereas the molecular vibrations of M2C4N were studied through Fourier transform infrared (FTIR) and FT-Raman spectral analysis using the polycrystalline powders derived from the single crystals. In addition, quantum chemical studies on M2C4N molecule were performed by using density functional theory (DFT) at the B3LYP/6-311++G (d, p) basis set. These studies showed that the M2C4N is a phasematchable NLO crystal and could be used for device fabrication.

In this paper we report In 2 O 3 /CdSe quantum dot based non-volatile resistive memory device with ON/OFF ratio ∼1000. Indium nanostructures were grown by oblique angle deposition technique in a thermal evaporator. Indium oxide nanostructures had size ranging from 20 nm to 100 nm as observed from TEM and AFM methods. The facile device fabricated with a layer of CdSe quantum dot on indium oxide film exhibited excellent endurance characteristics over 100,000 switching cycles. Retention tests showed good stability for over 4000 s. Memory operating mechanism is proposed based on charge trapping/de-trapping in quantum dots with indium oxide acting as barrier leading to Coulomb blockade. The mechanism is supported by negative differential resistance (NDR) observed exclusively in the ON state.

The sensing response of the chief Silicane nanosheet with the pollutant gases CO, NO, CO2, NO2 and SO2 are mainly investigated in this research article using ab-initio method. The formation energy is calculated initially, in order to ensure the stability of Silicane nanosheet and its value is calculated as −4.143 eV/atom. Further to ensure the dynamical stability of Silicane nanosheet, phonon band spectrum is plotted. The electronic characteristics and geometrical stability of Silicane nanosheet are investigated before performing the adsorption studies. Then the reaction between the chief substance Silicane nanosheet and the pollutant gases are analysed, with the help of adsorption energy, Bader charge transfer, energy band gap, and a change in band gap, together with DOS and energy band spectrum. Without pollutant adsorption, the energy band gap of Silicane nanosheet is observed as 3.167 eV. Though, the energy band gap of Silicane nanosheet is varied due to the adsorption of CO, NO, CO2, NO2 and SO2. Thus, the end result of this research indicates that Silicane nanosheet can be utilized as an effective sensing material for sensing pollutant gases particularly NO, NO2 and SO2.

The proposed research article investigates on the adsorption behaviour of the prime substance blue phosphorene nanosheet (BPNS) with the pollutant vapours CO, CO2, NO and NO2 by utilizing ab-initio method. Initially the BPNS stability is guaranteed by calculating its formation energy and it is calculated as −4.149 eV/atom. Before performing the adsorption studies, the structural and electronic characteristics of BPNS are investigated. Then the interaction between the prime substance BPNS and the pollutant vapours are analysed with the support of adsorption energy, energy band gap, Bader charge transfer, and a change in band gap together with DOS and energy band structure spectrum. The humidity effects on BPNS have also been studied by sensing the H2O molecule. The energy band gap of BPNS without pollutant adsorption is observed as 1.999 eV. Though, the adsorption of CO, CO2, NO and NO2 vary the energy gap of BPNS. Thus, the outcome of this research suggests that BPNS can be used as an efficient sensing material for pollutant vapours especially NO and NO2 even in the humidity environment.

We present an all-solution processed bipolar non-volatile resistive memory device with CdSe quantum dot/metal–metal oxide/quantum dot structure. The two terminal device exhibits excellent switching characteristics with ON/OFF ratio >104. The device maintained its state even after removal of the bias voltage. The switching time is around 14 ns. Device did not show degradation after 4000 s retention test. The memory functionality was consistent even after multiple cycles of operation (100,000) and the device is reproducible. The switching mechanism is discussed on the basis of charge trapping in quantum dots with metal oxide serving as the barrier. The mechanism is supported by observation of variation in capacitance–frequency measurements.

The title compound, 2-amino-4-picolinium-nitrophenolate-nitrophenol (2A4PNN), has been synthesized and optical quality single crystals of 2A4PNN were grown by solution growth technique. The crystal structure was solved by single crystal X-ray diffraction method. The 2A4PNN molecule was found to possess intermolecular herringbone structure and to crystallize in orthorhombic crystal system with a noncentrosymmetric space group of Pna21 (Point group mm2). The functional groups of 2A4PNN were confirmed through FT-IR and Raman vibrational spectroscopic studies and NMR spectrum was recorded to study its molecular structure. The UV–Vis and photoluminescence spectra were recorded to explore its optical transmittance and emission properties respectively. The SHG efficiency and phasematchability were investigated through Kurtz and Perry powder technique using sieved/graded powders derived from polycrystals of 2A4PNN. The laser damage threshold studies of 2A4PNN single crystal were performed on (1 0 0) plane using a pulsed Nd:YAG laser (1064 nm). The third-order optical properties of 2A4PNN single crystal were measured by Z-scan technique. In addition, the quantum chemical studies were performed on the isolated 2A4PNN molecule using density functional theory (DFT) calculations at the B3LYP/6-311++G (d, p) basis set.

Growth of thin and flexible organic semiconductor crystal Anthracene (AN) has been achieved in a very short duration. This simple, yet an effective approach was serendipitously found to yield high quality crystal with typical dimensions of 22×23×0.15–0.50 mm 3 within a duration of about 30 min whereas a conventional method could take about 7–10 days to achieve similar dimensions. Further, these crystals were seen swirling and settling down slowly at the bottom of the growth flask. These factors were favorably utilized to place the Anthracene crystals firmly on prefabricated flexible substrates when they were kept in different heights within the solutions. This systematic approach also facilitated the fabrication of organic field effect transistor (OFET) and the results obtained were encouraging.

Excellent open circuit voltage $(V_{oc})$ reported by Si Heterojunction (Si-HJ) solar cells has been a topic of considerable interest among the PV community. One of the reasons attributed to this large $V_{oc}$ is the reduction of interface recombination due to the presence of an inversion layer at a-Si:H/cSi interface. Here, we employ deep level transient spectroscopy (DLTS) measurements of silicon heterojunction cells (Si-HJ) to probe process induced interface traps at the a-Si:H/cSi interface. Interestingly, contrary to literature reports, we find both majority and minority peaks in differently processed Si-HJ solar cells - a result which could have interesting implications towards performance optimization.

Synthesis, characterisation and single crystal X-Ray studies of 2-(4-methoxyphenyl)-1,4,5-triphenyl-2,5-dihydro-1H-imidazole are reported. Here after the compound is denoted as TSI. Small Angle X-Ray Diffraction (SXRD) showed that the crystal belonged to Monoclinic, P21/c group. The electronic and structural properties of TSI were investigated by DFT and TD-DFT methods. This molecule is a good candidate to be used in OLED devices because of high electron transport mobility and low λe value. The difference between λe and λh is smaller so that it has a better hole-electron transport balance in OLED devices. The calculated static first order hyperpolarizability β(000), showed that the material exhibited good non-linear optical behaviour and could be used for NLO devices. Fukui indices were calculated to identify the reactive sites of the title compound.

The brown mussel Perna perna , an effective bioindicator species for monitoring radioactive pollution, was used to evaluate the concentration of 210 Po in and around the coastal areas of Kanyakumari, a Monazite rich region. 210 Po concentration in P. perna collected from ten different locations in this region exhibited values ranging between 78.09 ± 5.5 and 320.00 ± 18.1 Bq/kg (wet). Kalluvilai recorded the maximum concentration of 210 Po (320.00 ± 18.1 Bq/kg), and hence further studies involving the activity of 210 Po in other marine organisms and terrestrial samples were carried out from this site. The annual intake of 210 Po by the population residing in this location via dietary sources was estimated. Similarly, the total annual committed effective dose to the public was found to be 2.24 mSv/year. The results obtained were compared to the values reported by earlier studies in India and also in other countries.

The core and surface terminal groups are the two main catalytic sites in a dendrimer. In most of the reported examples, the catalytic sites in dendritic catalysis are the surface terminal functional groups. This perspective article concerned with the dendrimer based catalysis, involving these two catalytic sites and the dendrimer cavities. The interior cavities provide the nanoscale reactor sites, by creating reverse micelle like appearance for catalysis. In exploring the significant achievements in this area, a low generation PAMAM dendrimer with amphiphilic nature, having a polymeric core with large number of pendent amino groups was synthesized and concentrated its catalytic activity. The key features with respect to positive and/or negative catalytic activity was highlighted by synthesizing various aryl and heteroaryl 2-substituted benzimidazoles. The synthesized dendritic organocatalyst was proved to be amazingly reactive and gave high yield of products within a few minutes at room temperature with low catalyst loading. Here, a new stable hemiaminal, the species rarely been detected and much less isolated in bulk, was obtained during the synthesis of benzimidazoles. Moreover, this is the first reported method for the synthesis of benzimidazoles, using the homogeneous PAMAM dendrimer as a basic organocatalyst.

Organic thin film transistors were fabricated using evaporated zinc phthalocyanine as the active layer. Parylene film prepared by chemical vapour deposition was used as the organic gate insulator. The annealing of the samples was performed at 120 °C for 3 h. At room temperature, these transistors exhibit p-type conductivity with field-effect mobilities ranging from 0·025–0·037 cm2/Vs and a (Ion/Ioff) ratio of ∼103. The effect of annealing on transistor characteristics is discussed.

In this study, we report the observation of memory effect in TiO2–GO nanocomposite films. Electrical properties of the prepared Al/TiO2–GO composite/ITO devices have shown stable and reproducible bipolar resistive switching behavior. The TiO2–GO composite films were prepared using solution method by spin coating technique. Observed results have shown that the inclusion of GO in the TiO2 matrix have exhibited a significant role in the resistive switching mechanism. The device has exhibited an excellent memory characteristic with low operating voltages, good endurance up to 105 cycles and long retention time more than 5 × 10 3 s .

A series of clay supported metal containing catalysts were prepared and their catalytic performance was evaluated in the synthesis of tetrasubstitued imidazoles under solvent free condition. It was found that K10 supported titanium catalyst showed higher activity compared to other catalysts. The catalysts were characterized by FTIR, XRD, TG/DTA, BET surface area and SEM. The general applicability of the method was demonstrated for the synthesis of tetra- substituted imidazoles from aldehydes and amines containing various electron donating and electron withdrawing substituents. The diversity of the catalyst was studied by synthesis of benzimidazoles and quinoxalines. The mechanism of formation of the products is explained in detail. The catalyst was found to be active for three cycles.

Bulk single crystals of undeuterated Hydrazonium l -tartrate (HLT) an organic crystal have been grown by the isothermal solvent evaporation method. The occurrence of coloration of HLT solution which is reported to have hindered the growth of HLT crystals under normal ambient conditions has been deferred to a considerable duration by modifying the experimental conditions to facilitate the crystal growth. Studies such as powder X-ray diffraction (XRD) and Carbon, Hydrogen and Nitrogen (CHN) analysis confirmed that the crystals grown using modified growth conditions are indeed HLT. The powder second harmonic generation (SHG) efficiency of the HLT analyzed using Nd:YAG laser was about 1.5 times that of potassium dihydrogen phosphate (KDP), which is higher than the reported value. Dielectric tensor measurements exhibited the anisotropic nature of HLT single crystal. Optical transmission studies performed in the range 190–1100 nm revealed that the undeuterated HLT crystal could be suitable for optical applications.

Large-size inclusion-free RbTiOPO 4 (RTP) single crystals have successfully been grown from Rb 6 P 4 O 13 flux with the addition of a small amount of MoO 3 using TSSG technique. The solubility of RTP in the flux composition Rb 6 P 4 O 13 has been determined. Seed crystals were obtained by spontaneous nucleation process. The seed–liquid interface was maintained by the surface tension forces, and the criteria of avoiding the solution inclusion in the initial stages of the growth are discussed. Crystals grown from Rh-incorporated platinum crucibles shift the UV cut-off towards lower wavelength. The effect of coloration and impurities on optical properties were characterized by optical absorption spectra. Single-crystal X-ray diffraction has been carried out to evaluate the lattice parameters of the grown crystals. Average dislocation density was in the range 400–5000/mm 2 . Second harmonic generation (SHG) elements have been fabricated.

Montmorillonite K10 catalyzed synthesis of 2,4,6 triaryl pyridine under solvent free condition is described. Montmorillonite effectively catalyzed the reaction in good to excellent yields. Using this solid catalyst, the reactions could be carried out in a short period of time with very good yield of triaryl pyridines, up to 97% under solvent free condition. This catalyst could be recycled very easily, which makes this methodology environmentally benign. The catalyst is active over three cycles.

We report an efficient method for growing NiO nanostructures by oblique angle deposition (OAD) technique in an e-beam evaporator for supercapacitor applications. This facile physical vapor deposition technique combined with OAD presents a unique, direct, and economical route for obtaining high width-to-height ratio nanorods for supercapacitor electrodes. The NiO nanostructure essentially consists of nanorods with varying dimensions. The sample deposited at OAD 75° showed highest supercapacitance value of 344 F/g. NiO nanorod electrodes exhibits excellent electrochemical stability with no degradation in capacitance after 5000 charge–discharge cycles. The nanostructured film adhered well to the substrate and had 131% capacity retention. Peak energy density and power density of the NiO nanorods were 8.78 Wh/kg and 2.5 kW/kg, respectively. This technique has potential to be expanded for growing nanostructured films of other interesting metal/metal oxide candidates for supercapacitor applications.

Fabrication and characterization of graphene flakes sandwiched polymethyl methacrylate (PMMA) hybrid bistable devices (HBD) is reported in this paper. Graphene flakes (GFs) sandwiched polymer layers were prepared through a simple solution process. The fabricated memory devices have exhibited remarkable electrical bistable behavior even at 150°C. Bistable memory behavior of the fabricated devices have been described on the basis of current-voltage characteristics. Reasonably good ON/OFF current ratio (∼103) and retention property have been obtained from the constructed memory devices. The device showed excellent stability up to 105 switching cycles without any degradation both in ON and OFF states. The results obtained have indicated that the HBD fabricated by embedding graphene flakes in an insulating polymer matrix have potential applications in organic nonvolatile flash memory devices.

In this paper, we report a facile quantum dot/In–InOx(nanostructure)/quantum dot/In based non-volatile resistive memory device. The solution processed tri-layer structure exhibited bipolar resistive switching with a ratio of 100 between the high-resistance state and low-resistance state. The memory device was stable and functional even after 100,000 cycles of operation and it exhibited good retention characteristics. The ON/OFF switching ratio could be controlled by choosing appropriate metal in the structure. Memory operating mechanism is discussed based on charge trapping in quantum dots with InOx acting as barrier. A comparative study of memory devices consisting of aluminum and titanium in place of indium is presented. The possible reason for the variation in ON/OFF ratio is discussed on the size of the nano-sized grains of the middle metal layer.

Acetalation of pentaerithritol has been carried out in the presence of an Al-pillared saponite. Several carbonyl compounds were used, including aldehydes and ketones. Yields between 72 and 93% were obtained in all cases, except in the case of veratraldehyde where the carbonyl group was blocked. The high conversion could be explained by diffusion effects of intermediates and electronic effects between the reactants in the transition state. The catalyst was found to be active after three cycles.

Monocrystalline ZnO thin films on p-GaN/sapphire (0001) substrate were grown by single step hydrothermal technique at 90 °C. ZnO thin films were grown in aqueous solution of zinc nitrate and ammonium hydroxide. The X-ray diffraction, scanning electron microscopy and room temperature photoluminescence analysis were carried out to characterize structural, morphological and optical properties of the films. The thin films revealed single crystalline nature and wurtzite symmetry. The films were c-axis oriented and have honeycomb like pitted surface morphology. The epitaxial relationship between ZnO film and p-GaN buffer layer was observed to be (0001)[112¯0]ZnO||(0001)[112¯0]GaN. Sharp luminescent peak centered at 376 nm due excitonic emission and broad deep level emission peak were obtained from room temperature photoluminescence measurement of the ZnO thin film. © 2008 Elsevier B.V. All rights reserved.

Single crystalline ZnO thin film on p-GaN/sapphire (0 0 0 1) substrate, using two different precursors by hydrothermal route at a temperature of 90 °C were successfully grown. The effect of starting precursor on crystalline nature, surface morphology and optical emission of the films were studied. ZnO thin films were grown in aqueous solution of zinc acetate and zinc nitrate. X-ray diffraction analysis revealed that all the thin films were single crystalline in nature and exhibited wurtzite symmetry and c-axis orientation. The thin films obtained with zinc nitrate had a more pitted rough surface morphology compared to the film grown in zinc acetate. However the thickness of the films remained unaffected by the nature of the starting precursor. Sharp luminescence peaks were observed from the thin films almost at identical energies but deep level emission was slightly prominent for the thin film grown in zinc nitrate.

In this work, the effects of rice husk ash and metakaolin additions on magnesium sulfate and corrosion resistance properties of self-compacting concrete are reported. Comparisons are made to unblended self-compacting concrete to show the influence of the additions and replacements. Cement is replaced on a binary and ternary basis by 5–30% and 10–40%, respectively, of rice husk ash and metakaolin. Magnesium sulfate and corrosion resistance are analyzed after magnesium sulfate immersion for one year and with an accelerated corrosion test. The observational results showed that specimens exposed to a 5% magnesium sulfate solution exhibited the lowest weight loss for 10% rice husk ash, 20% metakaolin, and 20% rice husk ash in combination with metakaolin-blended self-compacting concrete. Likewise, it was noted that the tricalcium aluminate content of the binder influences the sulfate and the corrosion properties of self-compacting concrete.

L(+)Glutamic acid hydrochloride [HOOC (CH2)2CH(NH2) COOH·HCl], a monoamino dicarboxylic acid salt of L-Glutamic acid was synthesized and the synthesis was confirmed by FTIR analysis. Solubility of the material in water was determined. Pure and Thiourea doped L-Glutamic acid hydrochloride crystals were grown by low temperature solution growth using solvent evaporation technique. XRD, UV-Vis-NIR analyses were carried out for both pure and thiourea doped crystals. The crystals were qualitatively analyzed by EDAX analysis and the presence of thiourea was confirmed. The cell parameters of L-Glutamic acid hydrochloride have been determined as a = 5.151 A, b = 11.79 A, c = 13.35 A by X-ray diffraction analysis and it crystallizes in orthorhombic space group P212121. UV-Vis-NIR spectra analysis showed good optical transmission in the entire visible region for both pure and doped crystals. Micro hardness of both pure and doped crystals has been determined using Vickers micro hardness tester. The SHG efficiencies of both pure and doped crystals were determined using Kurtz powder test and pure L-Glutamic acid hydrochloride crystal was found to possess better efficiency than thiourea doped L-Glutamic acid hydrochloride crystals. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Single-crystal growth of 4-hydroxy-3-methoxy benzaldehyde (vanillin), an excellent molecular nonlinear optical (NLO) material, from the melt using the Bridgman technique is reported for the first time. Differential thermal analysis experiments indicated that the substance melts congruently at 81 °C. A precise temperature profile plot of the resistive furnace used was measured using a simple PC-based time–temperature data logging system. Powder X-ray diffraction analysis of the grown crystal revealed the crystal belongs to the monoclinic system. Fourier transform infrared spectra were used to assign various modes and identify the functional groups. The crystal exhibited a wide window of transmission unlike other organic NLO crystals. The optical second harmonic generation conversion efficiency of vanillin was determined using the Kurtz powder technique. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Single crystals of l-histidine monohydrochloride (LHMHCl) and l-histidine dihydrochloride (LHDHCl) have been grown from aqueous solution by a slow evaporation technique. Single-crystal X-ray diffraction analyses reveal that LHMHCl crystallizes in orthorhombic form with space group P212121 while LHDHCl crystallizes in monoclinic form with space group P21. Laser Raman studies confirmed the structure of the crystal, and the vibration modes have been assigned. UV−vis−NIR spectra show excellent transmission through the visible region up to 1100 nm. Differential thermal analysis (DTA) studies indicate that the LHMHCl crystal is more stable and has higher melting point than the LHDHCl crystal. Laser damage threshold study shows that LHDHCl is more resistant to laser damage than LHMHCl. Crystals of the monoclinic form LHDHCl give strong second-harmonic generation (SHG) signals, while orthorhombic forms do not.

A group of 300 subjects of both sexes were measured for total body potassium content using a shadow shield whole-body counting system at Kalpakkam (India). The mean body potassium content for males was 1.7 +/- 0.5 g kg(-1) body weight and 1.5 +/- 0.5 g kg(-1) body weight for females. The body potassium content varies inversely with age as well as with the body weight for both the sexes. However, the total body potassium varies directly with body-build index for both males and females. The mean annual dose due to (40)K for males and females was found to be 149 +/- 44 and 132 +/- 41 uGy, respectively.

Single crystals of pure and Lanthanum added KDP crystals were grown from aqueous solution. The influence of La3+ ions in KDP crystals is studied. Isolated centers are formed by La3+ ions in KDP structure along (100) plane. La3+ ions incorporated into superficial crystal growth layer and slightly affect the growth process as they generate weak lattice stresses. The creation of these weak lattice stress is confirmed by Vickers's micro hardness test. The HRXRD analysis showed reduced structural defects in the La added KDP in the (100) plane than pure KDP. The incorporation of La in the crystal was confirmed by EDAX analysis. The Kurtz's powder SHG efficiency was found to be 1.5 times that of pure KDP. The UV-Vis transmission spectra of La added KDP showed excellent transmittance from 1100 nm to 340 nm and did not show any change in lower cutoff wavelength with respect to pure KDP. Laser damage threshold value has been determined using Q-switched Nd:YAG laser operating at 1064 nm and with 65 ns pulses in single shot mode. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

L-Methionine doped TGS single crystals were grown using solution method. Ferroelectric hysteresis loop could be traced at room temperature under conditions of external electric field. The measurements in the present study were performed on single domain samples of 7 mm thick L-.Methionine doped TGS. X-ray diffraction (XRD) studies have been carried out to confirm the peak position. TGA and DTA studies were also carried out and the thermal properties have been analyzed. Electrical conductivity measurements were carried out at different temperatures and as a function of low and high frequency ranges. The conductivity of the L-Methionine doped TGS crystals was found to depend strongly on the frequency of the measuring electric field at different temperatures.

Sodium acid phthalate (NaAP), a new semi-organic nonlinear optical material, has been synthesized and single crystals were grown from aqueous solution. The FTIR spectrum confirms the compound formation. Single crystals of NaAP have been grown by slow evaporation of solvent at room temperature up to dimensions of 10 mm×5 mm×3 mm. Powder X-ray diffraction study on grown crystals shows that they belong to an orthorhombic system. The UV–Vis–NIR transmission spectrum has been recorded in the range 200–1100 nm. The second harmonic generation conversion efficiency of NaAP was determined using Kurtz powder technique; it was observed that it has double the efficiency of KAP crystals. The laser damage threshold value was determined using a Q-switched Nd:YAG laser operating at 1064 nm and with 65 ns pulses in single shot mode.

Diastereoselective Baylis–Hillman reaction using different sugar-derived aldehydes with various activated olefins afforded chiral multifunctional adducts in good yields. Steric factors that dictate and determine the diastereoselection will be discussed.

Anhydrous FeCl3 and Yb(OTf)3 are utilised as new reagents for the stereoselective isomerisation of acetates of the Baylis–Hillman adducts to both (Z) and (E) trisubstituted alkenes respectively.

Chiral 2,3-epoxy aldehydes have been effectively utilized for the first time as novel electrophiles in Baylis–Hillman reactions with activated alkenes to result in densely functionalized adducts in good yields (61–80%) and in moderate to good diastereoselectivities (40–72% de).

A new semi-organic nonlinear optical crystal Bisthiourea-zinc Acetate (BTZA) has been grown and characterized. The solubility study was carried out in aqueous solution. Crystals were grown from low temperature solution method by slow evaporation technique. Powder XRD and FTIR have confirmed the formation of the new crystal. UV-Vis-NIR spectra analysis showed good optical transmission in the entire visible region. The optical second harmonic generation conversion efficiency of BTZA was determined using Kurtz powder technique. The SHG efficiency was better than materials like KDP and CTA.

N-methylprolinol is used as a chiral base catalyst for the Baylis–Hillman reaction to obtain the adducts in good yields with moderate to good enantioselectivities in 1,4-dioxane:water (1 : 1, v/v) under ambient conditions.

Crystals listed in the JCPDS card in BaO-B2O3-Al2O3 and BaO-B2O3-Ga2O3 systems were synthesized by means of a solid-state reaction method and a liquid-state reaction method. Synthesized crystals were characterized from a viewpoint of Second Harmonic Generation (SHG) and crystal growth possibility. Ba5Al4B12O29 and Ba5Ga4B12O29 are promising new candidate crystals from the viewpoint of SHG activity and congruent melting behavior. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Single crystals of cadmium thiourea acetate (CTA), a semi-organic nonlinear optical material, have been grown from a low-temperature solution method by a slow evaporation method at ambient temperature. Powder X-ray diffraction pattern and FTIR spectrum analysis has confirmed the formation of the new crystal. CTA has good optical transmission in the entire visible region, which is an essential requirement for a nonlinear crystal. The optical second harmonic generation conversion efficiency of CTA was determined using Kurtz powder technique. The microhardness and thermogravimetric-differential thermal analysis of the grown crystal were studied.

N-Methylmorpholine and urotropine, inexpensive mild bases, have effectively been utilized as catalysts in Baylis-Hillman reaction to result in good to excellent yields (57-99%) of the products.

Luminescence signals have been recorded at low temperature during thermal cycling of crystals of RbTiOPO4 (RTP) and KTiOPO4 (KTP) excited by x-rays. In both crystals there are well resolved intense intensity spikes and changes in emission spectra consistent with first-order phase transitions. The transitions are not reversible, except by high temperature annealing. The observations imply that new phases of RTP and KTP can be formed, and in some cases these may relate to nanoparticle-size inclusions. Crystal quality assessment from the luminescence behaviour may have value for non-linear optics. Cathodoluminescence of the RTP surface reveals different emission spectra from the bulk material with consequent implications for usage in surface waveguide devices.

KTiOPO 4 single crystals doped with trivalent impurity ions of chromium were grown by spontaneous nucleation and seeded growth techniques. Structural refinement performed on the grown crystals by single crystal X-ray diffraction technique reveals that chromium ions occupy both the potassium sites with different filling coefficients. Incorporation of Cr 3+ causes the absorption edge in the UV spectrum to shift towards the lower energy. The dependence of optical absorption coefficient with the incident photon energy in the UV–VIS region has been discussed. Optical and SEM studies indicate the existence of two-dimensional nucleation mechanisms.

Gaseous bubble inclusions in bismuth germanate (BGO) and bismuth germanium silicon oxide (BGSO) crystals were studied by means of Raman spectroscopy at room temperature. Their Raman spectra in the range from 60 to 70 cm−1 showed three peaks for the rotational Raman modes of O2 and N2. Vibrational Raman modes of O2 and N2 were also recorded for BGO and BGSO crystals. It was found that all the rotational and vibrational modes were blue shifted from those of free molecules due to the hydrostatic pressure in the bubbles. Internal pressure in the bubbles was estimated from the rotational and vibrational Raman mode frequencies. O2 gas pressure in the bubble was estimated as 140 GPa, and N2 gas pressure, as 31 GPa. The pressure coefficient of the vibrational mode frequency of O2 (0.368 cm−1/GPa for O2 vibrational mode of 1580 cm−1) and N2 (0.322 cm−1/GPa for N2 vibrational mode of 2331 cm−1) was also obtained from the blue shift and the calculated bubble pressure.

The impedance and dielectric properties of a RbTiOPO 4 (RTP) crystal along the three principal axes were studied from room temperature to 900°C in the frequency range 100 Hz-10 MHz. The dielectric anomaly of RTP is around 800 ± 4°C and it exhibits a second-order phase transition. The dielectric anomaly near T c is pronounced along the polar c-axis compared to the anomaly along the a- and b-axes. Suppression of the dielectric constant and loss factor is observed along the polar axis, which indicates an alteration of the transport mechanism in RTP crystals below a critical temperature. Complex impedance measurements predict the existence of non-Debye relaxation along the polar axis.

KTiOPO 4 single crystals of dimensions 34x15x15 mm 3 have successfully been grown by Top Seeded Solution Growth (TSSG), using phosphate flux (K 6 P 4 O 13 ), employing a home made vertical cylindrical three zone resistive heated furnace. Growth experiments were carried out with seed orientation. A method to grow inclusion free crystal with less dislocation density is proposed, by employing cooling rate of 0.5-2 K/day and rotation rate of 60-30 rpm. UV-VIS transmission studies were performed and the dependence of absorption coefficient with wavelength is discussed. SHG elements of dimension 8x7.5x7.5 mm 3 were fabricated and conversion efficiency of 58 % was achieved without antireflection coating. Nature of ionic conductivity and ferroelectric phase transition behavior of KTP crystals along the crystallographic polar axis in the frequency range of 100 Hz - 10 MHz are discussed.