Transition Metal Ion–Mediated Tyrosine‐Based Short‐Peptide Amphiphile Nanostructures Inhibit Bacterial Growth

We report the design and synthesis of a biocompatible small‐peptide‐based compound for the controlled and targeted delivery of encapsulated bioactive metal ions through transformation of the internal nanostructures of its complexes. A tyrosine‐based short‐peptide amphiphile (sPA) was synthesized and observed to self‐assemble into β‐sheet‐like secondary structures. The self‐assembly of the designed sPA was modulated by application of different bioactive transition‐metal ions, as was confirmed by spectroscopic and microscopic techniques. These bioactive metal‐ion‐conjugated sPA hybrid structures were further used to develop antibacterial materials. As a result of the excellent antibacterial activity of zinc ions the growth of clinically relevant bacteria such as Escherichia coli was inhibited in the presence of zinc ? sPA conjugate. Bacterial testing demonstrated that, due to high biocompatibility with bacterial cells, the designed sPA acted as a metal ion delivery agent and might therefore show great potential in locally addressing bacterial infections.     

Waste Eggshell-Derived Calcium Oxide and Nanohydroxyapatite Biomaterials for the Preparation of LLDPE Polymer Nanocomposite and Their Thermomechanical Study

Waste eggshells were utilized to make calcium oxide (E-CaO) and hydroxyapatite (E-HAP). E-CaO obtained by heat treatment to eggshells was utilized for the synthesis of E-HAP. Melt compounding of E-CaO/E-HAP was performed with linear low-density polyethylene (LLDPE) on a Brabender Plastograph and ground the obtained formulation for injection molding. Addition of E-CaO/E-HAP in the LLDPE significantly enhanced the flame retardant ability and thermal stability of resultant composites. In the comparative study, E-HAP nanopowder-containing polymer composite showed increment in thermal and mechanical properties than the composite prepared using E-CaO.     

Hen Egg White Lysozyme Catalyzed Efficient Synthesis of 3-Indolyl-3-hydroxy Oxindole in Aqueous Ethanol

A green synthesis of 3-indolyl-3-hydroxy oxindoles was reported using hen egg white lysozyme (HEWL) in an aqueous ethanol. The HEWL promotes this reaction efficiently from various isatins and indoles under mild reaction conditions with yields up to 98% bearing good adaptability to varied substrates in the reaction. This conversion has provided a new strategy to synthesize 3-indolyl-3-hydroxy oxindole derivatives employing biocatalytic promiscuity of less explored lysozyme. Based on the experimental studies, the plausible reaction mechanism is proposed.

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Multilayered Distributed Routing for Power Efficient MANET Performance

In this paper a new power efficient routing algorithm for MANETs with self-organizing and self-routing features is described and its performance analyzed in different simulation scenarios. The algorithm has the logic of a non-cooperative routing algorithm based on the evaluation of a weight parameter, the latter being a function of properties of the MANET nodes related to the nominal available power and the transmission range. A self-estimation of this weight parameter for each node is introduced in the routing process based on the status and functional history of the node. The routing is based on network layering, formation of service areas in each layer and choice of nodes from these areas to have the functionality of default gateways. The proposed algorithm, named service zone gateway prediction (SZGP), is a hybrid type of routing mechanism, incorporating pre-computed multipath hop-by-hop distributed routing, with a periodically updated hierarchical multilayered structure. The results from the simulation experiments show that the performance of the proposed SZGP algorithm in relation to the basic performance parameters such as packet delivery ratio, delay and throughput are similar to those of the well-known AODV algorithm, but in relation to power efficiency the proposed algorithm outperforms AODV significantly. This is due to the fact that such an approach reduces the overall number of broadcasts in the network and ensures a reliable and energy efficient connection by balancing the load among the nodes.     

Lipoxygenase and Tocopherol Profiling of Soybean Genotypes Exposed to Electron Beam Irradiation

Electron beam (EB)-irradiation is increasingly being preferred to radioactive-based gamma irradiation in overcoming the constraints that affect the quality of food material. Soybean seeds of 3 soybean genotypes were exposed to 4 doses viz. 4.8, 9.2, 15.3 and 21.2 kGy of EB-irradiation and assessed for the changes in the contents of lipoxygenase isozymes and tocopherol isomers. Densitometry of protein profile revealed decreasing intensity of lipoxygenase with increasing EB dose. All the 3 lipoxygenase isozymes viz. lipoxygenase-1, -2 and -3 registered significant (P < 0.05) increasing reduction with increasing dose; though genotypic variation was noted for the magnitude of reduction at the same dose. Concomitantly, all the 3 genotypes exhibited significant (P < 0.05) decline in α-, γ- and δ-isomers of tocopherol. δ-Tocopherol was the most sensitive to EB-irradiation. EB dose, which caused minimum and maximum decline in total tocopherol content, was genotype-dependent. Decline in vitamin E activity corresponding to the dose, which induced maximum reduction for total lipoxygenase also varied in 3 genotypes. The study showed the usefulness of EB for significant inactivation of off-flavor generating lipoxygenases in soybean, with a non-significant effect on oil content and varied retention of tocopherol isomers and vitamin E activity depending upon genotype.     

Thickness dependent structural, electronic, and optical properties of Ge nanostructures

In the present paper, we have investigated structural, optical as well as electronic properties of electron beam evaporated Ge thin films having layer thicknesses ranging from ultra-thin (5 nm) to thick (200 nm). The Raman spectra show that all peaks are shifted towards lower wave number as compared to their bulk counterparts and are considered as a signature of nanostructure formation and quantum confinement effect. The Raman line exhibits transformation from nanocrystalline to microcrystalline phase with a reduction in blue shift of peak position with increase in Ge film thickness (>5 nm). Similarly, the optical absorption spectra corresponding to these films also show reduction in blue shift effect, although Ge 5 nm film shows the absorption behaviour quite different from higher thickness films. The corresponding band gap values obtained from absorption measurements are much larger than bulk Ge and are mainly attributed to the effect of quantum confinement as expected for small size particles calculated from GIXRD patterns. AFM data in each case are correlated and discussed with structural as well as optical results to support the effect of growth morphology on the above-mentioned observations. The results are further supported by photoelectron spectroscopy (PES), photoluminescence (PL) and resistivity measurements and are interpreted in terms of crystallinity and quantum confinement effect.     

An empirical correlation for estimating the viscosity of non-Newtonian waxy crude oils

Non-Newtonian fluids are the most complex ones when it comes to predicting their flow behavior. In the pre-existing models, rheological behavior in waxy crude oils is mainly affected by shear rate and thermal history of crude oils. In the present work, rheological characteristics of four different crude oils were studied by coaxial cylindrical rheometer at three different temperatures (40°C, 50°C, and 60°C) and a model was proposed keeping into consideration wax content for the first time. This model is prepared to predict the viscosity of four different crude oils with different wax content and at different temperature. The proposed model can efficiently estimate the viscosity as compared to other established models.     

Optimization of Fenton-biological treatment scheme for the treatment of aqueous dye solutions

Degradation of dyes especially, azo dyes are difficult due to their complex structure and synthetic nature. The main objective of this study was to evaluate the Fenton-biological (aerobic) treatment train for decolorization and mineralization of azo dyes viz. Reactive Black 5 (RB5), Reactive Blue 13 (RB13) and Acid Orange 7 (AO7). The objective of Fenton treatment was only to decolorize the dyes (breakage of -NN-), as it was considered that after breakage of -NN-, the dyes will become amenable to biodegradation and can be further treated in aerobic biological system. Hence studies were carried out to optimize the lower Fenton's doses for decolorization of dyes. The optimum doses for decolorization (>95%) of all the three dyes were found out to be 15 mgL(-1) of Fe(2+) (0.27 mM) and 50 mgL(-1) (1.47 mM) of H(2)O(2) dose at optimum pH 3. Further it was also investigated that at lower doses, the main problem of Fenton process (sludge generation) can also be minimized. Later the mineralization of the dye (removal of aromatic amines) was achieved in the aerobic biological treatment system. Overall reduction of 64, 89 and 75% in the aromatic amines (at 254 nm), 88, 95 and 78% in naphthalene ring associated compounds (near 310 nm) and 49, 89 and 91% reduction in benzene ring associated compounds (near 226 nm) were observed for RB5, RB13 and AO7, respectively. Thus this treatment system seems to be quite effective and economical option for the treatment of recalcitrant compounds like dyes, as the cost in the chemical treatment is considered mainly due to chemicals thus at lower doses the operational cost is saved. Further, as the sludge generation was almost negligible at lower doses, thus the savings in cost of handling and disposal of hazardous sludge also adds to economy of treatment.     

Influence of precursors of Li2O and MgO on surface and catalytic properties of Li‐promoted MgO in oxidative coupling of methane

The influence of the catalyst precursors (for Li₂O and MgO) used in the preparation of Li‐doped MgO (Li/Mg = 0.1) on its surface properties (viz basicity, CO₂ content and surface area) and activity/selectivity in the oxidative coupling of methane (OCM) process at 650–750 °C (CH₄/O₂ feed ratio = 3.0–8.0 and space velocity = 5140–20550 cm³ g⁻¹ h⁻¹) has been investigated. The surface and catalytic properties are found to be strongly affected by the precursor for Li₂O (viz lithium nitrate, lithium ethanoate and lithium carbonate) and MgO (viz magnesium nitrate, magnesium hydroxide prepared by different methods, magnesium carbonate, magnesium oxide and magnesium ethanoate). Among the Li–MgO (Li/MgO = 0.1) catalysts, the Li–MgO catalyst prepared using lithium carbonate and magnesium hydroxide (prepared by the precipitation from magnesium sulfate by ammonia solution) and lithium ethanoate and magnesium acetate shows high surface area and basicity, respectively. The catalysts prepared using lithium ethanoate and magnesium ethanoate, and lithium nitrate and magnesium nitrate have very high and almost no CO₂ contents, respectively. The catalysts prepared using lithium ethanoate or carbonate as precursor for Li₂O, and magnesium carbonate or ethanoate, as precursor for MgO, showed a good and comparable performance in the OCM process. The performance of the other catalysts was inferior. No direct relationship between the basicity of Li‐doped MgO or surface area and its catalytic activity/selectivity in the OCM process was, however, observed. © 2000 Society of Chemical Industry     

Cancer-Associated Fibroblasts in Pancreatic Ductal Adenocarcinoma: An Update on Heterogeneity and Therapeutic Targeting

Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of cancer-related morbidity and mortality in the western world, with limited therapeutic strategies and dismal long-term survival. Cancer-associated fibroblasts (CAFs) are key components of the pancreatic tumor microenvironment, maintaining the extracellular matrix, while also being involved in intricate crosstalk with cancer cells and infiltrating immunocytes. Therefore, they are potential targets for developing therapeutic strategies against PDAC. However, recent studies have demonstrated significant heterogeneity in CAFs with respect to their origins, spatial distribution, and functional phenotypes within the PDAC tumor microenvironment. Therefore, it is imperative to understand and delineate this heterogeneity prior to targeting CAFs for PDAC therapy.