Synthesis,spectroscopic characterization,and biological screening of levofloxacin based organotin(IV) derivatives

Four new organotin (IV) complexes with general formula R₃SnL/R₂SnL₂, where R = CH₃, n-C₄H₉, C₆H₅ and L = Levofloxacin, were synthesized and characterized by elemental analyses, FT-IR and NMR (¹H and ¹³C) spectroscopy. Spectroscopic data suggested a six-coordinated geometry for diorganotin(IV) derivatives and a five-coordinated geometry for triorganotin(IV) derivatives. The value of Me–Sn–Me bond angle for di- and trimethyltin complexes using the Lockhart equation, were 150° and 116°, respectively, that corresponded to six and five-coordinate geometry, accordingly. The ligand and its complexes were screened for their antibacterial, antifungal, cytotoxic, and free radical scavenging (DPPH) antioxidant activities. The biological data indicated those as potentially bioactive in each field of the study. Accumulated data of DNA interaction with the synthesized complexes based on UV-Vis, cyclic voltammetry and viscometry suggested an intercalative mode of the interaction.     

Dual confinement of sulphur with rGO-wrapped microporous carbon from β-cyclodextrin nanosponges as a cathode material for Li–S batteries

A novel approach is developed to synthesize microporous carbon spheres with pore size ranges from 5 to 11 Å from hyper-cross-linked polymer β-cyclodextrin. Sulphur is incorporated in the micropores by solution impregnation followed by melt infusion. The resultant carbon sulphur (C/S) composite is wrapped in reduced graphene oxide (rGO) to provide conductive pathways to access the sulphur in micropores and to protect the surface-adhered sulphur. The cathode material obtained from rGO wrapping delivers initial discharge capacity of 1103 mA h g^?1 at 0.1 C, maintaining a capacity of 626 mA h g^?1 at 0.2 C with capacity loss of 0.2% per cycle for more than 100 cycles. In another cell configuration using carbon paper as an interlayer, discharge capacity has raised to 850 mA h g^?1 at 0.2 C and maintained 86% of its capacity for 100 cycles with excellent rate capability and high Coulombic efficiency. The good performance may be referred to excellent conductive networks, porous architecture of carbon spheres and adsorption of catholyte by fibrous interlayer that can effectively reduce the polysulfide shuttling.     

Interference of ATP with the fluorescent probes YOYO-1 and YOYO-3 modifies the mechanical properties of intercalator-stained DNA confined in nanochannels

Intercalating fluorescent probes are widely used to visualize DNA in studies on DNA-protein interactions. Some require the presence of adenosine triphosphate (ATP). We have investigated the mechanical properties of DNA stained with the fluorescent intercalating dyes YOYO-1 and YOYO-3 as a function of ATP concentrations (up to 2 mM) by stretching single molecules in nanofluidic channels with a channel cross-section as small as roughly 100?×?100 nm². The presence of ATP reduces the length of the DNA by up to 11 %. On the other hand, negligible effects are found if DNA is visualized with the minor groove-binding probe 4′,6-diamidino-2-phenylindole. The apparent drop in extension under nanoconfinement is attributed to an interaction of the dye and ATP, and the resulting expulsion of YOYO-1 from the double helix.

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Graphical Abstract Nanochannel-stretched DNA (48.5 kbp) stained with YOYO-1 is sensitive to ATP concentration in buffer. Nanochannels with a cross-section of 80?×?80 nm² were used to stretch DNA.

     

Bioconvection Due to Gyrotactic Microorganisms in Couple Stress Hybrid Nanofluid Laminar Mixed Convection Incompressible Flow with Magnetic Nanoparticles and Chemical Reaction as Carrier for Targeted Drug Delivery through Porous Stretching Sheet

In this paper, the steady electrically conducting hybrid nanofluid (CuO-Cu/blood) laminar-mixed convection incompressible flow at the stagnation-point with viscous and gyrotactic microorganisms is considered. Additionally, hybrid nanofluid flow over a horizontal porous stretching sheet along with an induced magnetic field and external magnetic field effects that can be used in biomedical fields, such as in drug delivery and the flow dynamics of the microcirculatory system. This investigation can also deliver a perfect view about the mass and heat transfer behavior of blood flow in a circulatory system and various hyperthermia treatments such as the treatment of cancer. The simple partial differential equations (PDEs) are converted into a series of dimensional ordinary differential equations (ODEs), which are determined using appropriate similarities variables (HAM). The influence of the suction or injection parameter, mixed convection, Prandtl number, buoyancy ratio parameter, permeability parameter, magnetic parameter, reciprocal magnetic prandtl number, bioconvection Rayleigh number, coupled stress parameter, thermophoretic parameter, Schmidt number, inertial parameter, heat source parameter, and Brownian motion parameter on the concentration, motile microorganisms, velocity, and temperature is outlined, and we study the physical importance of the present problem graphically.     

Electrical characteristics of poly(methylsilsesquioxane) thin films for non-volatile memory

In this communication the electrical characteristics of poly(methylsilsesquioxane) (PMSSQ) thin films and the possibility of charge storage in the Au nanoparticle embedded PMSSQ film base memory element have been studied. PMSSQ films were sandwiched between Al and Si electrodes to fabricate metal-polymer-semiconductor (MPS) structures. The conduction mechanism in PMSSQ films has been investigated. The charge transport mechanism appears to be space charge limited current (SCLC) at the higher-voltage region. Various electrical parameters such as reverse saturation current, barrier height, ideality factor, rectification ratio, shunt and series resistance and charge carrier mobility in PMSSQ have been determined. C-V analysis is performed to confirm the memory effect for Au nanoparticles embedded MPS structures. A definite clockwise hysteresis is observed which indicates the possibility of charge storage in the Au nanoparticles embedded PMSSQ film.     

Analytical and numerical solution along with PC spreadsheets modeling for a composite fin

Heat transfer through composite fins is investigated by both analytical and numerical methods. In this regard, governing differential equations of the two dimensional fin and one dimensional cladding are studied to examine the effect of Biot number and ratio of thermal conductivities of the fin material to the cladding, on the dimensionless temperature profiles. The results show that one dimensional analysis, traditionally used in fin analysis, is not applicable for composite fins, particularly when the conductivity ratio of the composite fin materials is low. In addition, the use of spreadsheet programs in solving the fin problem is investigated in somewhat more detail with regard to the solution as well as presentation of the graphical results.     

Recent Advances in the Applications of Nanotechnology and Nanomaterials in the Petroleum Industry: A Descriptive Review

Nanotechnology applications are rapidly expanding in various fields because of its unique qualities, such as a large surface area. Also, the synthetic changes can be utilized to alter nanomaterial to fit into specialized necessities. From the last decade there is a tremendous increase in the utilization of nanotechnology and nanomaterials in the petroleum industry. The current review's main objective is to summarize numerous nanoparticle applications in the field of petroleum, bio-fuel formation, and clean-up treatments of oil spill-related issues with their existing challenges that may help improve further research.     

Temperature solutions due to time-dependent moving-line-heat sources

A closed-form model for the computation of temperature distribution in an infinitely extended isotropic body with a time-dependent moving-line-heat sources is discussed. The temperature solutions are presented for the sources of the forms: (i) $\dot Q_1 (t) = \dot Q_0 \exp ( - \lambda t)$ , (ii) $\dot Q_2 (t) = \dot Q_0 (t/t^ \star )\exp ( - \lambda t)$ , and $\dot Q_3 (t) = \dot Q_0 [1 + a\cos (\omega t)]$ , whereλ andω are real parameters andt? characterizes the limiting time. The reduced (or dimensionless) temperature solutions are presented in terms of the generalized representation of an incomplete gamma function Γ (α,x;b) and its decompositionsC _Γ andS _Γ. It is also demonstrated that the present analysis covers the classical temperature solution of a constant strength source under quasi-steady-state situations.     

Prediction of roll temperature with a non-uniform heat flux at tool and workpiece interface

In a metal forming process, plastic deformation of the workpiece takes place at tool and workpiece interface region. Tool has been identified as one of the key parameters in controlling the productivity of any manufacturing industry. The deformation of metals and friction at the contact region produce large amount of heat, a part of that heat is conducted towards the tool where it is removed by forced convection. These cooling and heating cycles finally result in a substantial change in the temperature distribution in the roll. In this paper, an attempt is made to study the temperature and heat flux distribution in the roll by considering a non-uniform heat flux at the roll-workpiece interface for a cold rolling process. Adopting an elemental approach, a methodology has been proposed to model non-uniform heat flux at the interface. For this purpose both tool and workpiece has been considered together, thus a coupled approach is used to model both deformation and heat transfer phenomenon. It is demonstrated that the present approach of modeling is more general than that available in the literature. For example, a constant value of heat flux at the interface that is considered by several investigators is shown to be a special case of the present investigation, particularly when the deformation and relative velocity is very small. It is shown that the error in maximum temperature associated with constant heat flux assumption could be more than 5% in situations when reduction and relative velocity is high. The results are presented for temperature and heat flux distributions in the roll for different operating conditions.a thermal diffusivity, (m²/sec) - B pre-strain coefficient - C yield stress at unit strain, (N/m²) - e rate of deformation heat generation per unit volume, (W/m³) - f friction factor - h heat transfer coefficient, (W/m² °C) - k thermal conductivity, (W/m °C) - K yield stress at unit strain, (N/m²) - L bite length, (m) - n strain hardening exponent - P pressure between tool and workpiece, (N/m²) - q heat flux, (W/m²) - q_f friction heat flux, (W/m²) - heat flux entering towards the roll for any arbitrary element j (W/m²) - R roll radius, (m) - S_o yield stress in plane strain, (N/m²) - T temperature difference (T = T_r – T_o), (°C) - T surrounding temperature, (°C) - y strip thickness, (m) - V_rel relative slipping velocity, (m/sec) - V velocity, (m/sec) - Pe Peclet number - Bi Biot number - _T Total bite angle - mean effective strain - mean true stress, (N/m²) - mean strain rate - friction stress, (N/m²) - coefficient of friction - angle between heating and cooling regions - angle of cooling spray region - r, polar coordinates - x, y Cartesian coordinates - o initial value - f final value - r related to roll - s related to strip - a average value - j elemental region