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PyMOL and UCSF Chimera are open source multifunctional molecular visualization system developed for the use in structural biology. Both of these tools are well designed with various visualization options available for the user; with the help of such options, we have observed that the iron core binds oxygen in the heme group of oxymyoglobin. Also, various molecular surfaces, internal structures as well as bond lengths between the iron core & molecular oxygen in the heme group and that to the histidine-93 of the oxymyoglobin protein have been calculated. Implementing structural analysis feature of UCSF Chimera, the distance between iron core of heme group and molecular oxygen and that between iron core and histidine 93(H93) have been estimated and found to be 1.827 Å and 2.065 Å respectively which are in good agreement (within 0.5% error) with the bond lengths calculated by x-ray diffraction method [4] .The small value of bond length between Fe and O2 suggests the higher stability of oxygen which is important for transportation, activation and storage of enzymes to support life of living organisms on the Earth. So, it provides an insight in enzymology like oxygenase. Interestingly, oxymyoglobin protein or its constituent amino acid chain may have important role in the origin of early life on the Earth.

Cyanophycin granule polypeptide (CGP), a polymer of aspartic acid and arginine, synthesized by cyanophycin synthetase can be converted to polyaspartate which has many industrial applications. Cyanophycin and cyanophycin synthetase from a thermophilic cyanobacterium Chlorogloeopsis fritschii have been studied expecting enzyme from this organism to be thermostable. The organism exhibited best growth in Chu-10 medium at 45 °C. Maximum amount of cyanophycin was observed on 21 d when organism entered into stationary phase. Optimum conditions for cyanophycin synthetase were 30–40 °C and pH 8.0–9.5. The enzyme showed high specificity to aspartic acid and arginine but synthesized polyaspartate when arginine was omitted from the assay mixture. The enzyme activity doubled when Zn2+ were used as cofactor in place of Mg2+. The enzyme exhibited good thermal stability as it showed 66% activity when treated with 45 °C for one hour. Since cyanophycin synthetase formed an industrially valuable molecule polyaspartic acid and showed thermal stability, it has potential applications which needs to be further investigated.

Acrylonitrile butadiene styrene (ABS) nanocomposites with multiwalled carbon nanotubes (MWCNTs), reduced graphene oxide (RGO) and graphene oxide-carbon nanotubes (GCNTs) reinforced acrylonitrile butadiene styrene (ABS) composites were prepared using twin screw extruder. The effect of these reinforcements on dynamic rheological properties of composites was studied. Different carbon nanofillers significantly enhanced the viscoelastic properties of nanocomposites. The rheological studies showed that the material undergoes viscous to elastic transition for 5 wt % MWCNTs, 10% RGO and 7% GCNTs reinforced in ABS matrix. GCNTs hybrid composites show a higher dispersion as well as effectiveness for increased filler amount as compared to RGO and MWCNTs based ABS composites. The dynamic intersection frequency of GCNTs-ABS composites indicates its superiority over MWCNTs and RGO based ABS composites by solving the problem of restacking of graphene and agglomeration of MWCNTs. Modified Carreau-Yasuda model and Hershcel-Bulkey model have been used to determine the yield stress of the composites and van Gurp-Palmen plot to determine the viscoelastic properties. These models were used to compare the theoretical results with experiment data. Dynamic rheological measurements revealed the viscous-like (G">G') behavior at the lower loading of filler and elastic like (G'>G") behavior at higher loading of carbon nanofiller.

Sundarijal River supply drinking water in Kathmandu city, Nepal and to study the nitrate concentration, 10 different sample from different locations of the Sundarijal River was taken. The method for the removal of presence nitrate in River was tested using hydroxylamine hydrochloride dose at 25±2 0C with 35 minutes contact time. Samples was tested for different dose of hydroxylamine hydrochloride and reduction of nitrate increase with increasing hydroxylamine hydrochloride dosages, up to certain limit. That mean with 0.5g, 0.6g and 0.8g dosages of hydroxylamine hydrochloride, reduction of nitrate was not observed when tested with 10mg/L, 50mg/L and 100mg/L river water, orderly. This tested samples shows the feasibility of nitrate removal from River water, Sundarijal.

Hydroxyapatite (HAP) is an attractive bio-material for new bone growth process, hard tissue repair, bioactivity, osteoblast adhesion and proliferation due to its physicochemical resembles natural apatite. The intrinsic brittleness and poor mechanical properties of HAP restrict it for potential clinical applications. This problem is undertaken by exploiting the unique properties of carbon nanofillers (carbon nanotube (CNTs), graphene oxide (GO), graphene oxide-carbon nanotube (GCNTs) hybrid) which are used as reinforcement for preparing the carbon nanofillers based HAP composites. The nanomechanical and in-vitro biocompatibility of carbon nanofiller reinforced HAP composites have been studied. Carbon nanofiller reinforced HAP composites led to an improvement in nanomechanical and biocompatibility properties. The nanoindentation hardness and elastic modulus of GCNTs-HAP composites are significantly higher than other carbon nanofiller reinforced composites and pristine HAP powder. The in-vitro cytotoxicity of the prepared carbon nanofillers reinforced HAP composites is examined using MTT-assay on the MDCK cell line. The prepared GCNTs-HAP composites containing 2% of GCNTs nanofiller show higher cell viability, improved compatibility, and superior one cell proliferation induction than the other carbon nanofillers and HAP. These findings will provide the new prospects for utilizing the GO and its hybrid in HAP composites in bone repair, regeneration, augmentation and implantation.

In this work, comparison of dielectric and impedance studies of multi-walled carbon nanotube (MWCNTs), graphene oxide-carbon nanotube (GCNTs) reinforced acrylonitrile–butadiene–styrene (ABS) composites prepared by twin-screw extruder with back flow channel have been carried out. The dielectric relaxation and impedance behavior of these polymer composites have been studied with varying wt. % of MWCNTs and GCNTs reinforced ABS matrix in the frequency range of 102–106 Hz. The results showed that the real part of the impedance of the composites with MWCNTs content of 7 wt % or higher exhibits frequency independent behavior at the low-frequency region, and GCNTs-ABS demonstrates frequency dependent. Also, the relaxation time decreases with increase in wt. % of carbon nanofillers due to the formation of an interconnecting path within the polymer matrix. The Nyquist plots for MWCNTs-ABS composites showed the appearance of a single semicircular arc, whose radius of curvature decreases with increase in MWCNTs loading, suggest the decrease in overall impedance of the composite with high amount of filler loading. The radius of arc in impedance spectra decreases with increasing the percentage of fillers indicating the occurence of conducting behavior. In GCNTs-ABS composites Nyquist plots showed the appearance of a single straight line. The dielectric responses of MWCNTs, GCNTs reinforced ABS composites were investigated. The dielectric constant of MWCNTs-ABS composites gets enhanced significantly with addition 0 to 3 wt % MWCNTs. Room temperature AC conductivity increased with increase in the wt. % of MWCNTs and GCNTs from 10−12 S/cm for the unfilled polymer to 10−5 S/cm for 10 wt % of MWCNTs-ABS and 10−7 S/cm for 10 wt % of GCNTs-ABS composites. The decrease in impedance and enhancement of dielectric properties were due to the interfacial polarization between MWCNTs and ABS. Improved conductivity of MWCNTs-ABS and GCNTs-ABS composites may be useful in electromagnetic interference (EMI) shielding and antistatic materials.

The synthesis of functional nano-particles via spray pyrolysis technique (SPT), especially those of catalytic nature, has attracted the interests of scientists and engineers, as well as industries. The rapid and high temperature continuous synthesis yields nano-particles with intrinsic features of active catalysts, that is, high surface area and surface energetic. For these reasons, SPT finds applications in various thermally inducible catalytic reactions. However, the design and synthesis of photocatalysts by SPT requires a knowledge set which is different from that established for thermal catalysts. Unknown to many, this has resulted in frustrations to those entering the field unprepared, especially since SPT appears to be an elegant tool in synthesizing oxide nano-particles of any elemental construct. From simple oxide to doped-oxide, and mixed metal oxide to the in situ deposition of noble metals, this Perspective gives an overview on the development of photocatalysts made by SPT in the last decade that led to a better understanding of the design criteria. Various challenges and opportunities are also highlighted; especially those beyond simple metal oxides, which perhaps contain the greatest potential for the exploitation of photocatalysts design by SPT. Journal of Institute of Science and TechnologyVolume 22, Issue 2, January 2018, Page: 109-116

Herein, hybridization of graphene nanosheets and carbon nanotubes (CNTs) has been made to solve the problem of restacking of graphene nanosheets and agglomeration of CNTs. The multiwalled carbon nanotubes (MWCNTs), reduced graphene oxide (RGO) and graphene oxide–carbon nanotubes (GCNTs) reinforced acrylonitrile butadiene styrene (ABS) composites have been prepared using micro-twin-screw extruder. The effect of these reinforcements on static and dynamic mechanical properties of composites is studied. The ultimate tensile strength and elastic modulus for 7 wt.% GCNT–ABS composites show enhancement of 26.1 and 71.3% over pure ABS matrix, respectively. Various parameters such as coefficient “C” factor (the ratio of storage modulus of the composite to polymer in glassy and rubbery regions), degree of entanglement, crosslink density and adhesion factor have been calculated to analyze the interaction between fillers and polymer matrix. The 3-D hybrid structure of GCNTs overcomes the associated problem of CNTs agglomeration and graphene restacking. GCNT hybrid composites show higher dispersion as well as effectiveness for increased filler amount as compared to RGO and MWCNTs based composites. GCNTs prove its superiority over MWCNTs and RGO by showing a synergistic effect in the glass transition temperature and storage modulus. Raman spectroscopy and scanning electron microscopy are used to confirm the interaction and distribution of the filler and matrix, respectively.

The dynamic mechanical properties of multiwalled carbon nanotube (MWCNTs) reinforced acrylonitrile butadiene styrene (ABS) high performance composites, which were prepared using a micro twin screw extruder with a back flow channel that enabled proper dispersion of MWCNTs into the polymer matrix are studied in detail. The dynamic characteristics of the MWCNTs/ABS composites, such as storage, loss modulus and damping factor were significantly affected by the incorporation of MWCNTs. The dynamic mechanical properties of polymers strongly depend on the adhesion of MWCNTs and polymer and entanglement density of the polymer chains in the presence of MWCNTs. Herein, the entanglement density and C-factor of MWCNTs/ABS composites are evaluated using the dynamic mechanical properties results obtained from a dynamic mechanical analyser and correlated with their mechanical properties. The entanglement density of the MWCNTs/ABS composites increased from 4.31 × 104 mol m−3 (pure ABS) to 7.6 × 104 mol m−3 (5 wt% MWCNTs/ABS composites). C-factor measures the effectiveness of the filler on the modulus of the composites, which decreased from 1.086 (1 wt% MWCNTs/ABS composites) to 0.78 (5 wt% MWCNTs/ABS composites), and beyond this loading, the value of C-factor began to increase; this showed that the utilization of 5 wt% MWCNTs in the ABS matrix is sufficient for their effective use. The “b” factor increased from 6.16 (1 wt% MWCNTs/ABS composites) to 7.625 (5 wt% MWCNT/ABS composites) and after that started to decrease. A larger value of “b” strengthens the MWCNTs/ABS matrix interaction. In addition, Cole–Cole analysis was carried out to understand the phase behaviour of the composites.

Vertically aligned carbon nanotube (VACNT) arrays are widely studied because of their immense potential in a wide range of applications. In order to tailor the properties of carbon nanotubes (CNTs) for a particular application, vertical alignment in the form of sheet is a major breakthrough. Herein we report an economic and effective strategy developed to synthesise aligned multiwalled carbon nanotube sheets using Al powder as buffer layer. We achieved easy growth of VACNTs sheets using toluene/ferrocene solution in a two-zone furnace by chemical vapor deposition method. First zone was set at temperature 200 ° C and other zone was set at temperature 750 ° C for the synthesis of VACNTs. Almost 500 µm long VACNT sheet was grown. We observed the significant growth of VACNT sheet on Al powdered quartz substrate in nitrogen medium. Uniform length of CNTs was maintained all over the sheet and additionally nitrogen is an economical alternative rather than other inert gases. Copyright © 2015 VBRI Press.

In-house synthesized multiwall carbon nanotubes (MWCNTs) have been dispersed in acrylonitrile butadiene styrene (ABS) using a micro twin-screw extruder with back flow channel. The electrical and mechanical properties of MWCNTs in ABS with different wt% have been studied. Incorporation of only 3 wt. % MWCNTs in ABS leads to significant enhancement in the tensile strength (up to 69.4 MPa) which was equivalent to 29% increase over pure ABS. The effect of MWCNTs on the structural behaviour of ABS under tensile loading showed a ductile to brittle transition with increase concentration of MWCNTs. The results of enhanced mechanical properties were well supported by micro Raman spectroscopic and scanning electron microscopic studies. In addition to the mechanical properties, electrical conductivity of these composites increased from 10−12 to 10−5 Scm−1 showing an improvement of ∼7 orders of magnitude. Due to significant improvement in the electrical conductivity, EMI shielding effectiveness of the composites is achieved up to −39 dB for 10 wt. % loaded MWCNTs/ABS indicating the usefulness of this material for EMI shielding in the Ku-band. The mechanism of improvement in EMI shielding effectiveness is discussed by resolving their contribution in absorption and reflection loss. This material can be used as high-strength EMI shielding material.

Carbon nanomaterials such as carbon nanotubes (CNTs), graphene and their hybrid have been studied extensively. Despite having excellent properties of CNTs and graphene have not yet been fully realized in the polymer composites. During fabrication agglomeration of CNTs and restacking of graphene is a serious concern that results in the degradation of properties of nanomaterials into the final composites. To improve the dispersion of CNTs and restacking graphene, in the present research work, we focused on the hybridization of graphene oxide and CNTs. Multiwalled carbon nanotubes (MWCNTs), functionalized carbon nanotubes (FCNTs), and graphene oxide-carbon nanotubes (GCNTs) reinforced acrylonitrile butadiene styrene (ABS) composites were prepared separately by vacuum filtration followed by hot compression molding. Further, dynamic mechanical analysis (DMA), and electromagnetic interference (EMI) shielding properties of ABS composites reinforced carbon nanofillers were investigated. The dynamic mechanical properties of polymers strongly depend on the adhesion of fillers and polymer, entanglement density of polymer chains in the presence of carbon fillers. The dynamic mechanical characteristics such as storage, loss modulus, and damping factor of prepared composites were significantly affected by the incorporation of MWCNTs, FCNTs, and GCNTs. Maximum EMI shielding effectiveness of −49.6 dB was achieved for GCNT-ABS composites which were highest compared to MWCNTs-ABS composites (−38.6 dB) and FCNTs-ABS composites (−36.7 dB) in the Ku band (12.4–18 GHz). These results depict the great potential of GCNTs-ABS composites to be used in various applications of efficient heat dissipative EMI shielding materials for electronic devices.

Dynamic rheological properties of multiwalled carbon nanotubes-(MWCNTs) reinforced acrylonitrile butadiene styrene (ABS) composites prepared by micro twin-screw extruder with back flow channel (used for proper dispersion) are reported. Scanning electron microscopic and high-resolution transmission electron microscopic studies showed that the nanotubes were uniformly dispersed in the ABS polymer matrix. MWCNT forms a network throughout the polymer matrix and thus promotes the reinforcement. The rheological studies showed that (for 3 wt% of MWCNTs loading) the material undergoes viscous to elastic transition. At a higher MWCNTs concentration nematic gel-like phase is observed where both storage and loss modulus (G′ and G″) are nearly independent of frequency. van Gurp–Palmen plot has been used to determine the viscoelastic properties. Dynamic intersection frequency has been used to correlate the rheological properties with different wt% of MWCNTs loading in ABS. Dynamic rheological measurements revealed the viscous-like (G″ > G′) behaviour at a lower MWCNTs loading ( 3 wt%).

Optical studies involving calculation of Band Gap of the synthesized copper nanoparticles were carried out in the wavelength range of 500 to 650 nm at room temperature, the particles showed high absorption at 550nm indicating their good absorptive properties. In this method water is used as the medium for reduction of copper ions in to copper Nanoparticles the stabilization of copper Nanoparticles was studied with starch both as a reductant and stabilizer,. The reaction mixture was heated using a kitchen microwave for about 5 minutes to attain the required temp for the reaction. The pH of the solution was adjusted to alkaline using 5%solution of NaOH. Formation of Copper Nanoparticles was indicated by change in color of the solution from blue to yellowish black which is supported by the UV absorption at 570nm.the synthesized particles were washed with water and alcohol. The optical properties depend upon absorption of radiations which in turn depends upon ratio of electrons and holes present in the materi...

Herein, multiwall carbon nanotubes (MWCNTs), reduced graphene oxide (rGO), graphene oxide-carbon nanotubes (GCNTs) hybrid reinforced acrylonitrile butadiene styrene (ABS) nanocomposites have been prepared by micro twin screw extruder with back flow channel and the effect of different type of fillers on the nanomechanical properties are studied. The combination of both graphene oxide and CNT has enhanced the dispersion in polymer matrix and lower the probability of CNTs aggregation. GCNTs hybrid have been synthesized via novel chemical route and well characterized using Raman spectroscopic technique. The nanoindentation hardness and elastic modulus of GCNTs-ABS hybrid nanocomposites were improved from 211.3 MPa and 4.12 GPa of neat ABS to 298.9 MPa and 6.02 GPa, respectively at 5wt% GCNTs loading. In addition to hardness and elastic modulus, other mechanical properties i.e. plastic index parameter, elastic recovery, ratio of residual displacement after load removal and displacement at the maximum load and plastic deformation energy have also been investigated. These results were correlated with Raman and X-ray photoelectron spectroscopic (XPS) techniques and microstructural characterizations (scanning electron microscopy). Our demonstration would provide guidelines for the fabrication of hard and scratches nanocomposite materials for potential use in, automotive trim components and bumper bars, carrying cases and electronic industries and electromagnetic interference shielding.

The plant Stevia rebaudiana is mainly found in tropical and subtropical regions from western North America to South America. This genus is having near about 240 species of shrubs and herbs in the sunflower family (Asteraceae). It exhibits various properties such as antibacterial, antifungal, anti-inflammatory, antimicrobial, antiviral, antiyeast, cardiotonic, diuretic, hypoglycemic, hypotensive tonic, and vasodilator effect. It is an important source of a number of antioxidants, for example, benzoic acid, caffeic acid, chlorogenic acid, ferulic acid, rozmaric acid, protocatechuic acid, salicylic acid, and their derivatives and flavonoids including campherol derivatives, catechin, and its derivatives, epicatechin, luteolin, and its derivatives, rutin, and its derivatives. Day by day, there is remarkable increase in demand of high potency sweeteners. The increasing number of diabetic patients and health conscious individuals would push forward the need for alternatives to sugar. The extract from leaves of Stevia is 200 times sweeter than sugar (glucose, fructose, sucrose, maltose, and lactose). Stevia is a potential alternative source for replacing artificial sweeteners such as saccharin, aspartame, and asulfam.

This review article presents in brief an overview of various technologies available based on coagulationflocculation methods. Coagulation and flocculation are among the most employed and documented techniques for arsenic removal from water. Arsenic is a human carcinogen in drinking water, having harmful effects on both human health and environment, even at low concentration. A limit of 0.01ppm (10 μg/L) has been set by WHO as the safe limit in drinking water, above which it shows health hazards. In coagulation method the, positively charged ion of coagulants {e.g., aluminum sulphate (Al 2 (SO 4 ) 3 ), ferric chloride (FeCl 3 )} neutralize or reduce the negative charge of colloids, thereby causing coagulation of particles. On the other hand in Flocculation the addition of an anionic flocculants leads to charge neutralization between the formed larger particles which ultimately change in to big flocs. As a result the dissolved arsenic is transformed into an insoluble solid. The precipitation or co precipitation with certain metal hydroxides can be done to remove arsenic from drinking water through sedimentation or filtration. The pH of the medium plays an important role in deciding the suitability of a coagulant for the removal of Arsenic. Below pH 7.5, Al 2 (SO 4 ) 3 , and FeCl 3 are equally effective in removing arsenic from water Between the two inorganic arsenic species, most researchers suggested that arsenate is more efficiently removed compared to arsenite and that FeCl 3 is a better coagulant than Al 2 (SO 4 ) 3 at pH higher than 7.5.There is no effective treatment for arsenic toxicity. Removal of arsenic from water is the one and only method of preventing its toxicity. A great deal of research over recent decades has been done to lower the concentration of arsenic in drinking water and still there is a need to develop low cost viable techniques. Existing major arsenic removal technologies include oxidation, adsorption, precipitation, coagulation and membrane separation. This paper presents the review of current status of research in the area of arsenic removal from contaminated water with coagulation and flocculation methods.