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Spontaneous mutations and lack of replication fidelity in positive-sense single stranded RNA viruses (+ssRNA virus) result in emergence of genetic variants with diverse viral morphogenesis and surface proteins that affect its antigenicity. This high mutability in +ssRNA viruses has induced antiviral drug resistance and ability to overcome vaccines that subsequently resulted in rapid viral evolution and high mortality rate in human and livestock. Computer aided vaccine design and immunoinformatics play a crucial role in expediting the vaccine production protocols, antibody production and identifying suitable immunogenic regions or epitopes from the genome sequences of the pathogens. T cell and B cell epitopes can be identified in pathogens by immunoinformatics algorithms and methods that enhance the analysis of protective immunity, vaccine safety, immunity modelling and vaccine efficacy. This rapid and cost-effective computational vaccine design promotes development of potential vaccine that could induce immune response in host against rapidly mutating pathogens like +ssRNA viruses. Epitope-based vaccine is a striking concept that has been widely employed in recent years to construct vaccines targeting rapidly mutating +ssRNA viruses. Therefore, the present review provides an overview about the current progress and methodology in computeraided vaccine design for the most notable +ssRNA viruses namely Hepatitis C virus, Dengue virus, Chikungunya virus and Coronaviruses. This review also highlights the applications of various immunoinformatics tools for vaccine design and for modelling immune response against +ssRNA viruses. [ABSTRACT FROM AUTHOR]

SARS-CoV-2 pandemic has become a major threat to human healthcare and world economy. Due to the rapid spreading and deadly nature of infection, we are in a situation to develop quick therapeutics to combat SARS-CoV-2. In this study, we have adopted a multi-level scoring approach to identify multi-targeting potency of bioactive compounds in selected medicinal plants and compared its efficacy with two reference drugs, Nafamostat and Acalabrutinib which are under clinical trials to treat SARS-CoV-2. In particular, we employ molecular docking and implicit solvent free energy calculations (as implemented in the Molecular Mechanics -Generalized Born Surface Area approach) and QM fragmentation approach for validating the potency of bioactive compounds from the selected medicinal plants against four different viral targets and one human receptor (Angiotensin-converting enzyme 2 -ACE-2) which facilitates the SARS-CoV-2 entry into the cell. The protein targets considered for the study are viral 3CL main protease (3CLpro), papain-like protease (PLpro), RNA dependent RNA polymerase (RdRp), and viral spike protein-human hACE-2 complex (Spike:hACE2) including human protein target (hACE-2). Herein, there liable multi-level scoring approach was used to validate the mechanism behind the multi-targeting potency of selected phytochemicals from medicinal plants. The present study evidenced that the phytochemicals Chebulagic acid, Stigmosterol, Repandusinic acid and Geranin exhibited efficient inhibitory activity against PLpro while Chebulagic acid was highly active against 3CLpro. Chebulagic acid and Geranin also showed excellent target specific activity against RdRp. Luteolin, Quercetin, Chrysoeriol and Repandusinic acid inhibited the interaction of viral spike protein with human ACE-2 receptor. Moreover, Piperlonguminine and Piperine displayed significant inhibitory activity against human ACE-2 receptor. Therefore, the identified compounds namely Chebulagic acid, Geranin and Repandusinic acid can serve as potent multi-targeting phytomedicine for treating COVID-19. [ABSTRACT FROM AUTHOR]

• Repurposing existing drugs for new diseases is cost effective and time saving. • In silico methods are crucial for rapid drug screening in the early stages. • Machine learning algorithms confer speed and accuracy to computational screening approaches. • Deep learning is immensely powerful to design molecules with desired properties. The current global health emergency in the form of the Coronavirus 2019 (COVID-19) pandemic has highlighted the need for fast, accurate, and efficient drug discovery pipelines. Traditional drug discovery projects relying on in vitro high-throughput screening (HTS) involve large investments and sophisticated experimental set-ups, affordable only to big biopharmaceutical companies. In this scenario, application of efficient state-of-the-art computational methods and modern artificial intelligence (AI)-based algorithms for rapid screening of repurposable chemical space [approved drugs and natural products (NPs) with proven pharmacokinetic profiles] to identify the initial leads is a powerful option to save resources and time. Structure-based drug repurposing is a popular in silico repurposing approach. In this review, we discuss traditional and modern AI-based computational methods and tools applied at various stages for structure-based drug discovery (SBDD) pipelines. Additionally, we highlight the role of generative models in generating molecules with scaffolds from repurposable chemical space. [ABSTRACT FROM AUTHOR]

[Display omitted] • Drug discovery projects can be benefited from the machine learning and deep learning based scoring functions. • The current review highlights various success stories in the identification of lead compounds using such scoring functions which are verified from experimental bioassay and characterization studies. A typical drug discovery project involves identifying active compounds with significant binding potential for selected disease-specific targets. Experimental high-throughput screening (HTS) is a traditional approach to drug discovery, but is expensive and time-consuming when dealing with huge chemical libraries with billions of compounds. The search space can be narrowed down with the use of reliable computational screening approaches. In this review, we focus on various machine-learning (ML) and deep-learning (DL)-based scoring functions developed for solving classification and ranking problems in drug discovery. We highlight studies in which ML and DL models were successfully deployed to identify lead compounds for which the experimental validations are available from bioassay studies. [ABSTRACT FROM AUTHOR]

Trans-1,2-dichloroethene (HClC=CClH) has several structural and dynamic anomalies between its low- and high-density liquid, previously found through neutron scattering experiments. To explain the microscopic origin of the differences found in those experiments, a series of molecular dynamics simulations were performed. The analysis of molecular short-range order shows that the number of molecules in the first neighbor shell is 12 for the high-density liquid and 11 for the low-density one. It also shows that the angular position of the center of mass of the first neighbor is roughly the same although the molecular orientation is not. In both liquids the first neighbor and its reference molecule arrange mainly in two configurations, each being the most probable in one of the liquids. First neighbors in the configuration that predominates in the high-density liquid tend to locate themselves closer to the reference molecule, an evidence that they are more strongly bonded. This arrangement facilitates a better packing of the rest of molecules in the first neighbor shell so that on average an additional molecule can be included, and is proposed to be the key in the explanation of all the observed anomalies in the characteristics of both liquids. [ABSTRACT FROM AUTHOR]

The present work addresses the solvatochromic shift of phenol blue (PB) dye. For this purpose the results of Car–Parrinello molecular dynamics (CPMD) simulations for PB in gas phase are compared with results obtained for PB in water from CPMD hybrid quantum mechanics-molecular mechanics (CPMD-QM/MM) calculations. The absorption spectra were obtained using the intermediate neglect of differential overlap/spectroscopic-configuration interaction (INDO/CIS) method and were calculated for a multitude of configurations of the trajectory. The calculated λmax for PB in gas phase was found to be about 535 nm, which is considerably lower than the λmax reported for PB in nonpolar solvents. Different solvation shells for PB in water have been defined based on the solute-all-atoms and solvent center of mass radial distribution function (g(rX–O)). The electronic excitation energies for PB computed in the presence of solvent molecules in an increasing number of solvation shells were calculated in a systematic way to evaluate their contributions to the solvatochrmic shift. The inclusion of solvent molecules in the hydration shell yields a λmax of 640 nm, which contributes to almost 78% of the solvatochromic shift. The inclusion of solvent molecules up to 10 Å in the g(rX–O) rdf yields a λmax of 670 nm which is in good agreement with the experimentally reported value of 654–684 nm. Overall, the present study suggests that the combined CPMD-QM/MM and INDO-CIS approach can be used successfully to model solvatochromic shifts of organic dye molecules. [ABSTRACT FROM AUTHOR]

We have studied the thermal behavior of orientationally disordered phase of caffeine molecular crystal using variable shape variable size Monte Carlo simulations in isothermal-isobaric ensemble. We have investigated the structure, especially the nature of orientational disorder of caffeine molecules as a function of temperature in the range of 400–550 K. Experimentally this system is known to undergo a phase transition at 426 K (considered to be an orientational order-disorder transition) and melt at 512 K. Our simulations reproduce these two transitions in excellent agreement with experiment. We find that the in-plane reorientational motion of molecules is restricted to small angles below 425 K, and above this temperature, molecules undergo essentially free rotations in molecular plane, and we find the melting to occur between 525 and 550 K. In the high temperature disordered phase, the disorder is mostly attributable to the in-plane orientational motion of the molecules. The potential energy profile for the in-plane reorientational rotation has six wells as a consequence of specific packing of molecules in the ab crystallographic plane. Also we find considerable out-of-plane reorientational disorder for the molecules in the high temperature disordered phase. We have also studied the structure and orientational disorder of the system that is quenched from 450 to 300 K. We find that in the quenched phase, the molecular orientational arrangement remains partially frozen. [ABSTRACT FROM AUTHOR]

The effect of pressure on the structure and reorientational motion of molecules in orientationally disordered (OD) crystalline phase of cubane has been investigated in detail using variable shape molecular simulations in constant-pressure constant-temperature ensemble. Complete orientational ordering occurs at a pressure of 1.0 GPa and the OD phase transforms to an orientationally ordered phase at this pressure. The transition is associated with a kink in the variation of structural parameters such as cell parameters, unit-cell volume, and interaction energy. This transition is also associated with an anomaly in specific heat. Above this transition pressure, the structural quantities display only smaller changes with further increase in pressure. The structure of high-pressure orientationally ordered (HPOO) phase has been characterized using radial distribution functions and orientational distribution function. From detailed analysis of the structure of HPOO phase we conclude that it is isostructural with low-temperature orientationally ordered phase. The OD phase has four times larger compressibility than the HPOO phase. [ABSTRACT FROM AUTHOR]

Extensive molecular simulations are carried out as a function of temperature to understand and quantify the conformational disorder in molecular crystals of 4-vinyl benzoic acid. The conformational disorder is found to be dynamic and associated with a flip-flop motion of vinyl groups. The population of minor conformer is less than 3% up to 300 K and is 13.2% at 350 K and these results are consistent with the experimental observations. At still higher temperatures, the population of minor conformer increases up to 25%. The evolution of structure at both molecular and unit-cell level of the molecular crystal as a function of temperature has been characterized by various quantities such as radial distribution functions, average cell parameters, volume, and interaction energies. The van’t Hoff plot shows a nonlinear behavior at lower temperatures as it has been reported recently by Ogawa and co-workers in the case of stilbene, azobenzene [J. Am. Chem. Soc. 126, 3539 (2004)], and N-(4-methylbenzylidene)-4-methylaniline [Acta Crystallogr, Sect. B. Struct. Sci. B60, 589 (2004)] molecular crystals. A set of rigid body simulations were also carried out to quantify the effect of conformational disorder on structural quantities such as unit-cell volume and interaction energy. The anomalous shrinkage of vinyl C==C bond length as a function of temperature has been explained by combining the results of simulations and a set of constrained optimizations using ab initio electronic structure calculations for various molecular structures differing in torsional angle. [ABSTRACT FROM AUTHOR]

Twitter, a social blogging site which became the tremendous topic in today's environment, which made several organizations and public to develop their identity and overwhelming through this social website. But unfortunately, twitter facing great challenges due to spammers who break the reputation of the website from deliberate users to stop using it. Researchers have proposed many techniques to overcome the issues faced by the spammers. As far researchers find a new path so as the spammers develop new techniques to travel in that path. So far, many algorithms were proposed to detect the spammers and some extraction techniques have developed to increase the potential of detection rate. In this paper, the main focus is about feature extraction of our data with a hybrid approach of combining logistic regression with dimensional reduction technique using principal component analysis. Our dataset contains 17 million users' tweets with 159 features included in it. Then we are going to extract particular features from it which would be helpful for the further process of increasing the classification accuracy. For the classification process, our work extended for the process of classification of data using some machine learning techniques. From the proposed work the detection rate could be increased by using particular features for the classification process. [ABSTRACT FROM AUTHOR]

Ascorbic acid (vitamin C, AA) is an important vitamin and essential component in the human diet. However, an unusual level of AA is generally a symptom of illness, and thus, the development of sensitive and selective detection methods for its biological analysis is important. Herein, we developed a new electrochemical sensor for the highly selective detection of AA using flower-structured molybdenum disulfide (MoS2)-decorated functionalized multiwall carbon nanotubes (f-MWCNTs)/zinc oxide (ZnO). The flower-structured MoS2 and ZnO nanoflakes were synthesized by hydrothermal and microwave-assisted solution methods, respectively. The surface morphology, particle size and elemental/chemical composition of the as-synthesized MoS2/f-MWCNTs/ZnO nanocomposite were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM) and energy dispersive X-ray spectroscopy (EDXS). Furthermore, the electrochemical properties of the MoS2/f-MWCNTs/ZnO nanocomposite were studied by cyclic voltammetry (CV). The MoS2/f-MWCNTs/ZnO-modified glassy carbon electrode (GCE) exhibited a high catalytic current for AA at a reduced overpotential in a 0.1 M phosphate buffer solution (PBS). The MoS2/f-MWCNTs/ZnO/GCE responded linearly from 10 to 100 μM AA at 0.21 V, and its limit of detection (LOD) was found to be 1.65 μM. In addition, the MoS2/f-MWCNTs/ZnO sensor offered fast electron transfer, good anti-interferent ability and stable response for AA sensing. The good solubility of f-MWCNTs in water was beneficial for the formation of the nanocomposite with MoS2 and ZnO via carboxyl groups, which created numerous catalytic centers to oxidize AA efficiently. This nanocomposite also blocked the adsorption of other species on the surface of the modified GCE. The proposed sensor offers high accuracy, sensitivity, simple fabrication and low cost. Finally, the MoS2/f-MWCNTs/ZnO nanocomposite sensor was used for AA analysis in real samples. [ABSTRACT FROM AUTHOR]

Purpose: Several tracers have been designed for tracking the abnormal accumulation of tau pathology in vivo. Recently, concerns have been raised about the sources of off-target binding for these tracers; inconclusive data propose binding for some tracers to monoamine oxidase B (MAO-B). Methods: Molecular docking and dynamics simulations were used to estimate the affinity and free energy for the binding of several tau tracers (FDDNP, THK523, THK5105, THK5317, THK5351, T807 [aka AV-1451, flortaucipir], T808, PBB3, RO-948, MK-6240, JNJ-311 and PI-2620) to MAO-B. These values were then compared with those for safinamide (MAO-B inhibitor). PET imaging was used with the tau tracer [18F]THK5317 and the MAO-B tracer [11C]DED in five patients with Alzheimer's disease to investigate the MAO-B binding component of this first generation tau tracer in vivo. Results: The computational modelling studies identified a binding site for all the tau tracers on MAO-B; this was the same site as that for safinamide. The binding affinity and free energy of binding for the tau tracers to MAO-B was substantial and in a similar range to those for safinamide. The most recently developed tau tracers MK-6240, JNJ-311 and PI-2620 appeared, in silico, to have the lowest relative affinity for MAO-B. The in vivo investigations found that the regional distribution of binding for [18F]THK5317 was different from that for [11C]DED, although areas of suspected off-target [18F]THK5317 binding were detected. The binding relationship between [18F]THK5317 and [11C]DED depended on the availability of the MAO-B enzyme. Conclusions: The developed tau tracers show in silico and in vivo evidence of cross-interaction with MAO-B; the MAO-B component of the tracer binding was dependent on the regional concentration of the enzyme. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Preparation of highly fluorescent carbon quantum dots (CQDs). • Cu2+ strongly quenched the fluorescent intensity as compared with the other metal ions. • Density functional theory revealed preferential binding between the carboxyl functionalized CQDs and Cu2+ ion. • CQDs have been applied in sensing of Cu2+ with a low detection limit (LOD) of 10 nM. • Sensing of Cu2+ in real tap and river water samples with excellent selectivity and high sensitivity. Abstract A facile, rapid and frugal approach was developed for the preparation of highly fluorescent carbon quantum dots (CQDs) by pyrolysis of Finger millet ragi (Eleusine coracana) as a carbon source. The optical properties of as-synthesized CQDs were analyzed by using UV-Visible and fluorescence spectroscopies. Fourier-transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) showed the formation of CQDs that predominantly consists of carbonyl and hydroxyl groups which can provide more adsorption sites. The X-ray diffraction (XRD), High-resolution transmission electron microscopy (HR-TEM) and Raman spectroscopy indicated that the synthesized CQDs made of amorphous graphitic carbon like structure. The size distribution was in the range of 3–8 nm with a high abundance of 6 nm particles. The CQDs exhibited bright blue fluorescence emission (wavelength ∼425 nm) under UV-light with an excitation wavelength of 340 nm. Our study indicated that Cu2+ strongly quenched the fluorescent intensity of CQDs compared to other metal ions (Al3+, Ca2+, Mg2+, Ni2+, Pb2+, Mn2+, Cr3+ and Hg2+). There was a linear correlation between the quenching efficiency vs. concentration of Cu2+ ions in the range from 0 to 100 μM (R2 = 0.9918). Furthermore, CQDs have been applied in sensing of Cu2+ in real water samples with a detection limit (LOD) of 10 nM. In addition, density functional theory (DFT) calculations revealed that there was a strong interaction between CQDs with divalent metal ions whereas trivalent metal ions adsorbed weakly. Particularly, Ni2+ and Cu2+ formed a very strong bonding with CQDs compared to other divalent ions. The metal-CQDs complex structure was reported with optimized highest occupied molecular orbital (HOMO) – lowest unoccupied molecular orbital (LUMO) energy gap. The nature of interaction and optical properties of the COOH-CQD's have been studied with metal ion adsorbed on the surface. Charge analysis corroborated that there was a significant charge transfer between CQDs with Ni2+ and Cu2+. Our study revealed that Cu2+ preferentially get adsorbed on aromatic C C (π-bond) of CQDs whereas other divalent metals form σ-bond(s) with the CQDs. This observation further confirmed by the HOMO-LUMO band gap (E g) and Frontier molecular orbital analysis. [ABSTRACT FROM AUTHOR]

Highlights • AISI 316L austenitic stainless steel is successfully joined using the FSW process. • Regression model is developed to predict the tensile strength of the joints. • The regression model is verified for adequacy using statistical tests. • The tensile strength of the joints is correlated to the microstructural features. • Nonlinear optimization method is used for maximizing tensile strength of the joints. Abstract AISI 316L stainless steel sheets were friction stir welded in the butt joint configuration as per the design of experiment (DoE) developed using the response surface method; Box Benkhen design. The primary friction stir welding (FSW) process parameters; tool spindle speed, tool transverse speed, downward force and tool tilt angle were considered as factors of the experiment. A response surface (second order) regression model for the response, ultimate tensile strength (UTS) of the joints as a function of tool spindle speed, tool transverse speed, downward force and tool tilt angle was developed. Statistical tests such as ANOVA, F- ratio and values of actual and adjusted R2 were used to verify the adequacy of the developed model and the model was validated using conformity experimental trials. The analysis of the model showed that the UTS of the joint is sensitive to all the primary FSW parameters. Also, the tool spindle speed, tool traverse speed and downward force have significant interaction effect on the UTS of the joints. The non-linear optimization of the FSW process yielded 604 MPa as optimal UTS corresponding to optimal tool spindle speed of 597 rev/min, tool traverse speed of 74 mm/min, downward force of 13 kN and tool tilt of 1.5°. [ABSTRACT FROM AUTHOR]

In this work, the effect of axial force on the tensile strength, microhardness, joint interface microstructure and fracture surface morphology of friction stir welded (FSW) dissimilar butt joints of 3 mm thick aluminum (Al) alloy AA5052-H32 and HSLA steel IRS-M42-97 were investigated. The FSW trials were carried out by varying the axial force from 5–9 kN while keeping the other parameters constant. The highest joint strength of about 90% of the ultimate tensile strength (UTS) of the base Al alloy is obtained at 7 kN axial force. It is found that axial force in the range, 6–8 kN could produce joints with joint strength above 75% of the UTS of the base Al alloy. EDS and XRD analysis suggests that the intermetallic compound (IMC) layer formed at the joint interface is consistent with FeAl3 and FeAl at lower and higher axial forces, respectively. Joint interface analysis shows that the thickness of IMC layer formed at the interface is critical in the performance of the joint and the joint with an average IMC layer thickness of about 1 μm at the joint interface has exhibited the highest joint strength. [ABSTRACT FROM AUTHOR]

Utilization of biomass as a renewable and sustainable resource has attracted much attention around the world. For the first time, a new and green method has been developed to synthesize fluorescent carbon dots (CDs) using flowers obtained from Borassus flabellifer (male tree) by thermal pyrolysis. The synthesized CDs were comprehensively characterized by X-ray diffraction, high-resolution transmission electron microscopy (HR-TEM), atomic force microscopy, zeta potential measurements, UV-Vis spectroscopy, fluorescence spectroscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. These studies confirmed that the as-synthesized CDs were functionalized with the (–OH), (C–H), (C–O–C) and (C=O) groups. TEM analysis revealed that the particle sizes of the CDs were in the 3 to 8 ± 1 nm range. Upon increasing the excitation wavelength from 300 to 400 nm, the emission spectrum shifted from 300 to 403 nm. Furthermore, the interaction between the CDs and metal ions was evaluated by testing with various metal ions and the fluorescence intensity of the CDs was measured under 320 nm excitation. Excellent fluorescence quenching was observed only for Fe3+ ions compared to other metal ions such as Zn2+, Pb2+, Ni2+, Fe2+, Ca2+, Cu2+, Cr3+, Co2+ and Hg2+. The fluorescence intensity decreased after each addition of Fe3+ ions. The CDs were an efficient probe for detection of Fe3+ ions from 0 to 30 nM with a detection limit of 10 nM. [ABSTRACT FROM AUTHOR]

Rolled sheets of 3 mm thick, AISI 316L austenitic stainless steel was successfully friction stir (FS) welded at different tool rotational speeds in the range from 400 rev/min to 800 rev/min with precisely selected constant values of other process parameters (welding speed of 45 mm/min, axial load of 12 kN and tool tilt angle of 1.5°). The microstructural characterization by orientation imaging microscopy (OIM) and transmission electron microscopy (TEM) revealed that discontinuous dynamic recrystallization was the dominant recrystallization mechanism in the stir zone. The grain size of the stir zone was greatly influenced by both heat generation and material strain rate. The shear bands were observed in the weld zone and the intensity of the shear bands was highly influenced by the deformation temperature. The results of the multi-spot energy dispersive spectroscopy (EDS) analysis within the narrow region of the shear bands depict the presence of tungsten traces for all the cases and, the minimal tungsten concentration was found in the weld joint made at 600 rev/min. The non-existence of secondary phases in the weld zone was owing to lower peak temperatures in FS welding. The base steel and the FSW joints depict a stable pitting potential after the activation controlled anodic region and the weld joints had marginally better pitting corrosion resistance than the base steel. [ABSTRACT FROM AUTHOR]

Nanomaterials have been at the center of attraction for almost five decades as their contributions to different disciplines such as electronics, photonics and medicine are enormous. Various kinds of nanomaterials have been developed and are currently utilized in innumerable applications. Nevertheless, their simple realization and easy and efficient upscaling are topics under intense investigation. Innovative strategies have been adopted for nanomaterial synthesis and their usability. Here, we provide a brief overview on nanomaterials ranging from basic understanding of their structure-property relationship to advanced applications. This editorial covers various aspects about nanomaterials, which will be useful/attractive for beginners in the field of nanotechnology as well as for experts and for industrialists looking forward to exploit them for real world applications. [ABSTRACT FROM AUTHOR]

Ambidextrous supergelators are developed through structure-gelation screening of rationally designed cyclic dipeptides (CDPs). The organo- and hydrogels of CDPs were thoroughly characterized by their minimal gelation concentration (MGC) for organic and aqueous solvents, thermal stability (Tg), and viscoelastic properties. Intermolecular hydrogen bonding, the major driving force for gelation was evaluated using temperature-dependent nuclear magnetic resonance (NMR) spectroscopy. The contribution of attractive van der Waals interaction of tBoc group in driving CDP gelation was ascertained using ß-cyclodextrin (β-CD)-adamantane carboxylic acid (AC)-based host-guest gelation and ¹H NMR studies. The self-assembled fibrous network of CDPs in organic and aqueous solvents responsible for the molecular gelation was elucidated using field emission scanning electron microscopy (FESEM) analysis. Among the CDPs studied CDP-2 found to be supergelator with MGC of 0.3 wt % and form in situ hydrogels under simulated physiological conditions. The in situ gelation property was evaluated by the incorporation of curcumin, as a model study to demonstrate the drug delivery application. Furthermore, supergelator CDP-2 was found to exhibit in cellulo cytocompatibility. Moreover, density functional theory (DFT) calculations were carried out to propose the microscopic structure for the self-assembly of CDP compounds and intermolecular N-H···O hydrogen bonding interactions appear to stabilize the fibrous network. The hydrophobic interactions among the tert-butyloxycarbonyl (tBoc) groups and p-p stacking interactions between phenyl rings contribute to the further stabilization of self-assembled 2D fibrous networks of CDPs. Overall, the present study highlights the in situ gelation property of CDP-based supergelators and their potential for biomedical and regenerative medicine applications. [ABSTRACT FROM AUTHOR]

A surface coating strategy encompassing the use of bioactive trace elements and reinforcing material will have significant influence on mechanical and osseointegration properties of bioceramic coated implants. Here, We attempted to mimic developed a minerals substituted and graphene oxide reinforced hydroxyapatite (Se,Mn-HAP/GO) composite coating on titanium (Ti) by electrodeposition which is a promising approach to produce bioimplants with better osseointegration capacity and improved mechanical property. Mechanical and biological studies were used to characterise the coatings. The composite coating on Ti was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM). Also, the corrosion resistance of the coatings was evaluated by electrochemical techniques in simulated body fluid (SBF) solution. The in vitro cell-material interaction of the composite coating was observed with human osteosarcoma MG63 cells for cell viability at 1, 2 and 3 days of incubation. From the results we believe that the (Se,Mn-HAP/GO) composite coating on Ti could provide effective corrosion protection, enhanced bioactivity. Thus, composite coated Ti can serve as a potential candidate for orthopedic applications. [ABSTRACT FROM AUTHOR]

The requirement of weight reduction, high thermal conductivity and strength at low temperatures and high corrosion resistance has identified the use of Al alloys together with steel in various fields. The use of Al alloys together with steel warrants efficient joining of Al alloys with steels. Friction stir welding (FSW) is a potential candidate for the joining of difficult-to-weld similar and dissimilar materials due to its inherent advantages as a solid state joining process. In order to speed up the research activities that lead to industrial level implementation of FSW of dissimilar Al alloys and steels, modelling and simulation can play a vital role. In this work, a central composite-response surface method (RSM) model is developed to predict the ultimate tensile strength (UTS) of friction stir-welded dissimilar Al alloy AA5052 H32 and HSLA steel IRS M-42-97. The adequacy of the model is verified by the analysis of variance (ANOVA) and computed values of the actual and adjusted R values. The model is validated by the results of experimental trials at parameter combination other than that experimented as per the DOE matrix and found in agreement with an average error of −0.34 %. From the analysis of the developed model, it is observed that the UTS of the joint is very sensitive to the primary FSW parameters, and, as such, the range of primary FSW parameters that could produce significant joint strength is very narrow. Also, it is observed that the tool rotational speed, welding speed and axial force have a significant interaction effect on the UTS of the joint. The analysis of the model and discussion on the effect of FSW parameters on the tensile strength of the joint are supported by the results of scanning electron microscopy and EDS analysis at the joint interface of selected joints. [ABSTRACT FROM AUTHOR]

We study the linear and nonlinear optical properties of a well-known acid-base indicator, bromophenol blue (BPB), in aqueous solution by employing static and integrated approaches. In the static approach, optical properties have been calculated using time-dependent density functional theory (TD-DFT) on the fully relaxed geometries of the neutral and different unprotonated forms of BPB. Moreover, both closed and open forms of BPB were considered. In the integrated approach, the optical properties have been computed over many snapshots extracted from molecular dynamics simulation using a hybrid time-dependent density functional theory/molecular mechanics approach. The static approach suggests closed neutral ⇒ anionic interconversion as the dominant mechanism for the red shift in the absorption spectra of BPB due to a change from acidic to basic pH. It is found by employing an integrated approach that the two interconversions, namely open neutral ⇒ anionic and open neutral ⇒ dianionic, can contribute to the pH-dependent shift in the absorption spectra of BPB. Even though both static and integrated approaches reproduce the pH-dependent red shift in the absorption spectra of BPB, the latter one is suitable to determine both the spectra and spectral broadening. Finally, the computed static first hyperpolarizability for various protonated and deprotonated forms of BPB reveals that this molecule can be used as a nonlinear optical probe for pH sensing in addition to its highly exploited use as an optical probe. [ABSTRACT FROM AUTHOR]

In the present research, the influence of friction stir welding (FSW) tool material on the mechanical and microstructural properties of friction stir (FS) welded 316L stainless steel butt joints is investigated. FS welds were produced using two different tungsten based FSW tools having identical tool shoulder and pin profiles. In both the cases, the FSW experimental runs were carried out using tool rotational speed of 600 rpm, welding speed of 45 mm/min, axial force of 11 kN and tool tilt angle of 1.5°. The results of the study show that the joints produced using the tungsten lanthanum oxide tool are having superior mechanical and microstructural properties when compared to the joints produced using tungsten heavy alloy tool. Furthermore, the tool degradation study by mass loss and photographic techniques suggests that the tungsten lanthanum oxide tool is more prone to degradation by plastic deformation, whereas the tungsten heavy alloy tool is more prone to degradation by wear. [ABSTRACT FROM AUTHOR]

Motivated by the outstanding properties of bis(BF2) core complexes as fluorophore probes, we present a systematic computational study of their vibrationally resolved one- and two-photon absorption spectra in vacuum and in solution. Electronic and vibrational structure calculations were performed using the coupled cluster CC2 method and the Kohn-Sham formulation of density functional theory (DFT). A nonempirical estimation of the inhomogeneous broadening, accomplished using the polarizable embedding (PE) approaches combined with time-dependent DFT and CC2 methods, is used as a key ingredient of the computational protocol employed for simulations of the spectral features in solution. The inhomogeneous broadening is also determined based on the Marcus theory employing linear response and state-specific polarizable continuum model (PCM) methods. It is found that the polarizable embedding CC2 and the state-specific PCM are the most successful approaches for description of environmental broadening. For the 1¹Ag → 1¹Bu transition, the non-Condon effects can be safely neglected and a fair agreement between the simulated and experimental band shapes is found. In contrast, the shape of the vibrationally resolved band corresponding to the two-photon allowed 1¹Ag → 2¹Ag transition is largely dominated by non-Condon effects. A generalized few-level model was also employed to analyze the mechanism of the electronic two-photon 1¹Ag → 2¹Ag excitation. It was found that the most important optical channel involves the 1¹Bu excited state. Ramifications of the findings for general band shape modeling are briefly discussed. [ABSTRACT FROM AUTHOR]

The Pot culture experiment performed for phytoextraction potential of selected agricultural plants [millet (Eleusine coracana), mustard (Brassica juncea), jowar (Sorghum bicolor), black gram (Vigna mungo), pumpkin (Telfairia occidentalis)] grown in metal contaminated soils around the Salem region, Tamilnadu, India. Physiochemical characterization of soils, reported as low to medium level of N, P, K was found in test soils. The Cr content higher in mine soils than control and the values are 0.176 mg/L in Dalmia soil and 0.049 mg/L in Burn & Co soil. The germination rate low in mine soil than control soils (25 to 85%). The content of chlorophyll, carotenoid, carbohydrate and protein decreased in mine soils than control. The morphological parameters and biomass values decreased in experimental plants due to metal accumulation. Proline content increased in test plants and ranged from 0.113 mg g−1to 0.858 mg g−1which indicate the stress condition due to toxicity of metals. Sorghum and black gram plants reported as metal tolerant capacity. Among the plants, Sorghum produced good results (both biomass and biochemical parameters) which equal to control plant and suggests Sorghum plant is an ideal for remediation of metal contaminated soils. [ABSTRACT FROM PUBLISHER]

The pH values for volumes (50 ml) of spring water were measured for 12 hours while being exposed to a weak (8±4 μT) decelerating frequency-modulated magnetic field that has been shown to diminish the growth of cancer cells and inhibit the movement of planarian. Compared to sham field-exposed water, the magnetic field-exposed water displayed a greater increase in pH (towards alkalinity) that involved an increase between 0.5 and 1 pH units after about 7 to 8 hr. This shift occurred slowly as successive 0.02 pH transient peaks (about 7 per s) that were between 20 to 40 ms in duration. This pattern was not observed in water exposed to background conditions (0.11 μT). These results are consistent with the hypothesis that properties of water exposed to specific patterns of magnetic fields produced by a patterned series of 3 ms voltage durations generated from computer software can produce transient temporal properties in water that converge with those associated with the cerebral cortical activity coupled to consciousness. Several quantitative solutions for small and very large volumes of water support this possibility. [ABSTRACT FROM AUTHOR]

In the present work 3 mm thick aluminium alloy AA5052 and HSLA steel were successfully butt joined using friction stir welding (FSW) technique. The FSW trials were carried out by varying the tool traverse speed while keeping the other parameters constant. The joint characteristics such as ultimate tensile strength (UTS), microhardness, microstructure at the joint interface and fracture surface of fractured tensile specimens were investigated. SEM and EDS analysis suggest that in all cases intermetallic compound (IMC) layer is formed at the joint interface and its thickness is critical in the tensile strength of the joint. For a given tool rotational speed, axial load and tool tilt angle, the tool traverse speed has significant influence on the thickness of IMC layer formed and hence on the joint strength. The highest joint strength of about 91% of UTS of the base aluminium alloy is obtained at tool traverse speed of 45 mm/min and the UTS follow approximately a centre peak type variation against tool traverse speed. [ABSTRACT FROM AUTHOR]

In the present work, the effect of tool axis offset from the joint interface and geometry of the FSW tool pin on the mechanical and metallographic characteristics of dissimilar friction stir butt welded aluminum (Al) alloy, AA5052 H32 and HSLA steel, IRSM42-93 were investigated. FSW tools having fixed shoulder diameter, pin tip diameter and pin length with three different tapered cylindrical (TC) and one straight cylindrical (SC) tool pin profiles were experimented. The constant FSW parameters used were: tool rotational speed of 500 rpm, welding speed of 45 mm/min, axial load of 7 kN and tool tilt angle of 1.5°. The effect of tool axis offset was investigated by continuously changing the tool axis offset by keeping the tool traverse direction at an angle to the joint interface. The ultimate tensile strength (UTS) of the joint is considered as the main criterion of the joint performance. The results show that the TC pin profile is beneficial and for a given FSW tool geometry and parameters, the taper angle of the tool pin and volume of tool pin penetration into steel side have significant influence on the thickness and composition of the intermetallic compound (IMC) layer formed and hence the joint performance. FSW tool having TC pin with 10° taper angle has produced the best joint at a tool axis offset of 2 mm towards the Al alloy. For the experimented tool pin geometries, the IMC layer formed at the joint interface is consistent with FeAl, Fe 2 Al 5 and FeAl 3 . [ABSTRACT FROM AUTHOR]

This study demonstrates that a hybriddensity functional theory/molecularmechanics approach can be successfully combined with time-dependentwavepacket approach to predict the shape of optical bands for moleculesin solutions, including vibrational fine structure. A key step inthis treatment is the estimation of the inhomogeneous broadening basedon the hybrid approach, where the polarization between solute andatomically decomposed solvent is taken into account in a self-consistentmanner. The potential of this approach is shown by predicting opticalabsorption bands for three heterocyclic ketoimine difluoroboratesin solution. [ABSTRACT FROM AUTHOR]

Friction stir processing (FSP) has evolved as a novel solid state technique to fabricate aluminium matrix composites (AMCs) in the recent years. FSP technique was applied to synthesis AA6082/TiC AMCs in order to analyze the effect of TiC particles, its volume fraction on the microstructure, mechanical and the sliding wear behaviour. A single pass FSP was carried out using a tool with 1200 rpm rotational speed, whose travel speed of 60 mm/min and an axial force of 10 kN to produce the composite. AMCs with five different volume fractions (0, 6, 12, 18 and 24 vol.%) were synthesized. The microstructure of the AA6082/TiC AMCs was studied using optical and scanning electron microscopy. The microhardness and ultimate tensile strength (UTS) were measured and the sliding wear behaviour was evaluated using a pin-on-disc apparatus. Thus the results revealed that the TiC particles significantly influenced the area of the composite, dispersion, grain size of matrix, microhardness, UTS and sliding wear behaviour of the AA6082/TiC AMCs. With this the effect of TiC particles on fracture surface and worn surface is also reported in this paper. [ABSTRACT FROM AUTHOR]

Based on electronic structure calculations we propose that particular small-sized organic molecules -- donor-acceptor substituted phenyl polymethines -- can be used as two-photon diagnostic probes for non-invasive imaging of amyloid oligomers and fibrils, which are often referred to as the "early signatures" of Alzheimer's disease. [ABSTRACT FROM AUTHOR]

Understandingthe working mechanism and establishing structure–propertyrelationships for optical probes is an essential step to develop designprinciples for novel molecular probes. Here we study optical propertiesof a small-sized dielectric probe, namely, 4-carbamido pyridiniumcyclopentadienylide (CPYC) in benzene and in water solvents usinga sequential approach. In particular, the structure modeling has beencarried out using a Car–Parrinello hybrid QM/MM molecular dynamicsapproach, while the excitation energies were computed using time dependentdensity functional theory. To incorporate the solvent effect eithera polarizable continuum model or a semicontinuum description was employed.The molecular dipole moment of CPYC in water is more than two timeslarger than in benzene solvent. The positive and negative chargestend to accumulate on pyridinium and cyclopentadienylide rings, respectively,with increasing solvent polarity. Significant solvent-induced geometricalchanges have been reported in CPYC and this contributes to a significantred shift in spectra. Even though the absorption maxima for CPYC inbenzene and water solvents were underestimated, the solvatochromicshift has been reproduced in good agreement with experiments. We alsoreport that CPYC can be used as a two photon probe. [ABSTRACT FROM AUTHOR]

Highlights: [•] AA6061/AlNp cast composite was welded by FSW process. [•] Regression models were developed to predict UTS and elongation of the FS welded joint. [•] FS welded joint using the optimized parameters exhibited maximum UTS and joint efficiency. [•] Defect free weld joint was obtained with optimized parameters value. [Copyright &y& Elsevier]

The objective of this work is to fabricate aluminium alloy AA6061 reinforced with ZrB2 particles (10 wt-%) by the in situ reaction of K2ZrF6 and KBF4 salts with molten aluminium. The microstructure, tensile strength, wear resistance and corrosion rate of the fabricated composite were compared with those of matrix alloy. The in situ formed ZrB2 particles were uniformly dispersed in the aluminium matrix predominantly concentrated in inter granular regions and refined the microstructure of the matrix alloy. The incorporation of in situ formed ZrB2 particles into the aluminium matrix improved tensile strength and wear resistance but reduced ductility and corrosion resistance. [ABSTRACT FROM AUTHOR]

Black carbon soot (BS) is consideredto be the second most contributingorganic matter next to carbon dioxide for the global warming effect.There is, however, so far no consensus on the quantitative warmingeffect due to the increased distribution of black carbon in the atmosphere.A recent report (Science2012, 337, 1078) suggests that due to BS there is only a few percentage enhancementin absorption of BS-immersed aerosols. To get proper interpretationof the available experimental data, it becomes essential to obtaindetails of the microscopic origin of the absorption and scatteringprocesses of the aerosol clusters due to the presence of soot. However,so far, due to the large spatial scale and the need for a quantummechanical description of the particles involved in the absorptionand scattering, this quest has posed an insurmountable challenge.In the present work we propose the use of a multiscale integratedapproach based on molecular dynamics and a quantum mechanical–molecularmechanical method to model the optical property of molecules immersedin nanosized aerosol particles. We choose fluoranthene (FA) with varying cis-pinonic acid (CPA) impurity concentration as an illustrativeexample of application. We observe that normally FA tends to be onthe surface of the nanoaerosols but in the presence of CPA impuritiesits spatial location changes to a core aggregate to some extent. Wefind that the absorption maximum is only slightly red-shifted in thepresence of increased CPA concentrations and that the oscillator strengthsare not altered significantly. The comparable values for the oscillatorstrengths of all the low energy excitations suggest that the absorptionenhancement of the aerosol due to BS will not be substantial, whichis in line with the recent experimental report in Science. [ABSTRACT FROM AUTHOR]

Highlights: [•] Fabrication of Cu/B4C surface composite by friction stir processing. [•] Development of empirical relationships to predict the properties of surface composite. [•] Analyzing the effect of FSP parameters on the properties of surface composite. [•] Explaining the effect of FSP parameters using microstructural characterization. [ABSTRACT FROM AUTHOR]

Friction stir processing has evolved as a novel method to fabricate surface metal matrix composites. The feasibility to make B4C particulate reinforced copper surface matrix composite is detailed in this paper. The B4C powders were compacted into a groove of width 0.5 mm and depth 5 mm on a 9.5 mm thick copper plate. A tool made of high carbon high chromium steel; oil hardened to 63 HRC, having cylindrical profile was used in this study. A single pass friction stir processing was carried out using a tool rotational speed of 1500 rpm, processing speed of 40 mm/min and axial force of 10 kN. A defect free interface between the matrix and the composite layer was achieved. The optical and scanning electron micrographs revealed a homogeneous distribution of B4C particles which were well bonded with the matrix. The hardness of the friction stir processed zone increased by 26% higher to that of the matrix material. [ABSTRACT FROM AUTHOR]

Dipolaraggregation is in many cases detrimental for the functioning of opticalmaterials. In this study we investigate self-aggregation and opticalabsorption of stilbazolium merocyanine (SM) in chloroform solutionby performing classical Molecular Dynamics (MD) simulations underambient conditions. The reversal solvatochromic shift, the large bathochromicshift, and the structured absorption band presented by SM in chloroformsolution are all aspects of its optical absorption behavior for whichthe existence of self-aggregation is yet not completely understood.Moreover, the spectroscopic properties of SM oligomers and their occurrencein solvent of low polarity remain a relevant topic that deserves tobe investigated. Our analysis of the aggregation behavior of SM inchloroform verified that the majority of the chromophores are involvedin the formation of oligomers in solution, where the whole dimer andpart of the trimer populations present a stable π-stacking structure.The optical properties of the monomers and oligomers in solution wereevaluated by means of a discrete polarizable embedding quantum mechanical/molecularmechanical (PE-QM/MM) response scheme where the quantum part is describedat the level of density functional theory. The visible absorptionspectrum of SM in chloroform is simulated using time average valuesobtained for the monomeric and oligomeric forms of SM from the PE-QM/MMcalculations performed on uncorrelated configurations extracted fromthe classical MD simulations. This study shows that the self-aggregationof SM in chloroform may exist, but it is not essential for reproducingthe reversal solvatochromic shift in chloroform and that the processdoes not contribute to enhance the bathochromic shift nor explainthe structure observed in its absorption band. Moreover, it is verifiedthat since the electronic transitions of the monomer and oligomersare close together, changes in the interplane separation between themonomeric units of the stacked oligomers substantially affect thespectral resolution of their contribution to the optical absorptionspectrum. [ABSTRACT FROM AUTHOR]

Friction stir processing (FSP) was applied to fabricate boron carbide (BC) particulate reinforced copper surface composites. The effect of FSP parameters such as tool rotational speed, processing speed and groove width on microstructure and microhardness was investigated. A groove was contrived on the 6 mm thick copper plates and packed with BC particles. FSP was carried out using five various tool rotational speeds, processing speeds and groove widths. Optical and scanning electron microscopies were employed to study the microstructure of the fabricated surface composites. The results indicated that the selected FSP parameters significantly influenced the area of surface composite, distribution of BC particles and microhardness of the surface composites. Higher tool rotational speed and lower processing speed produced an excellent distribution of BC particles and higher area of surface composite due to higher frictional heat, increased stirring and material tranportation. The BC particles were bonded well to the copper matrix and refined the grains of copper due to the pinning effect of BC particles. BC particles retained the original size and morphology because of its small size and minimum sharp corners in the morphology. [ABSTRACT FROM AUTHOR]

The poly(imide) (PI) based membrane plays a vital role in water purification field. Due to the absence of hydrophilic group and charged species, the PI membrane is easily attacked by water living microbial systems. This problem can be solved by the introduction of some ionic species onto PI backbone. Chemical grafting of chloroethylamine (CEA) and chloroaceticacid (CAA) onto PI was done in a single and two step processes in the presence of AlCl 3 as a Friedel-Crafts (FC) catalyst. Thus functionalized PI was characterized by FT-IR, 1H NMR, DSC, TGA, SEM, WCA, EDX, XPS, XRD and POM. The antibacterial and antifungus properties of PI4 system were tested. The FT-IR spectrum showed a small peak at 1623 cm−1 due to the zwitter ionic structure. The surface morphology was slightly changed while changing the grafting agent. The simultaneous grafting of CEA and CAA onto PI yielded better results. The thermal stability of PI before and after functionalization was compared with the recent literature reports. [Display omitted] • A zwitter ionic functionalized polyimide membrane was prepared. • The FTIR spectrum confirmed the formation of zwitter ionic structure. • The Zwitter ionic functionalized polyimide was characterized by various analytical methods. [ABSTRACT FROM AUTHOR]

[Display omitted] Stereoselectivity is important in many pharmacological processes but its impact on drug membrane transport is scarcely understood. Recent studies showed strong stereoselective effects in the cellular uptake of fenoterol by the organic cation transporters OCT1 and OCT2. To provide possible molecular explanations, homology models were developed and the putative interactions between fenoterol enantiomers and key residues explored in silico through computational docking, molecular dynamics simulations, and binding free energy calculations as well as in vitro by site-directed mutagenesis and cellular uptake assays. Our results suggest that the observed 1.9-fold higher maximum transport velocity (v max) for (R,R)- over (S,S)-fenoterol in OCT1 is because the enantiomers bind to two distinct binding sites. Mutating PHE355 and ILE442, predicted to interact with (R,R)-fenoterol, reduced the v max ratio to 1.5 and 1.3, respectively, and to 1.2 in combination. Mutating THR272, predicted to interact with (S,S)-fenoterol, slightly increased stereoselectivity (v max ratio of 2.2), while F244A resulted in a 35-fold increase in v max and a lower affinity (29-fold higher K m) for (S,S)-fenoterol. Both enantiomers of salbutamol, for which almost no stereoselectivity was observed, were predicted to occupy the same binding pocket as (R,R)-fenoterol. Unlike for OCT1, both fenoterol enantiomers bind in the same region in OCT2 but in different conformations. Mutating THR246, predicted to interact with (S,S)-fenoterol in OCT2, led to an 11-fold decreased v max. Altogether, our mutagenesis results correlate relatively well with our computational predictions and thereby provide an experimentally-corroborated hypothesis for the strong and contrasting enantiopreference in fenoterol uptake by OCT1 and OCT2. [ABSTRACT FROM AUTHOR]

Abstract: Friction stir processing has evolved as a novel solid state technique to fabricate surface composites. The objective of this work is to apply the friction stir processing technique to fabricate boron carbide particulate reinforced copper surface composites and investigate the effect of B4C particles and its volume fraction on microstructure and sliding wear behavior of the same. A groove was prepared on 6mm thick copper plates and packed with B4C particles. The dimensions of the groove was varied to result in five different volume fractions of B4C particles (0, 6, 12, 18 and 24vol.%). A single pass friction stir processing was done using a tool rotational speed of 1000rpm, travel speed of 40mm/min and an axial force of 10kN. Metallurgical characterization of the Cu/B4C surface composites was carried out using optical microscope and scanning electron microscope. The sliding wear behavior was evaluated using a pin-on-disk apparatus. Results indicated that the B4C particles significantly influenced the area, dispersion, grain size, microhardness and sliding wear behavior of the Cu/B4C surface composites. When the volume fraction of B4C was increased, the wear mode changed from microcutting to abrasive wear and wear debris was found to be finer. [Copyright &y& Elsevier]

Highlights: [•] AA6061/AlNp composite was welded by friction stir welding process. [•] Parameters considered in this study independently influenced the UTS of FS welded AMC. [•] AlNp are uniformly distributed in weld zone. [•] Size of AlNp is reduced in weld zone as compared with size of AlNp in base composite. [ABSTRACT FROM AUTHOR]

Along with the growing evidence that relates membrane abnormalities to various diseases, biological membranes have been acknowledged as targets for therapy. Any such abnormality in the membrane structure alters the membrane potential which in principle can be captured by measuring properties of specific optical probes. There exists by now many molecular probes with absorption and fluorescence properties that are sensitive to local membrane structure and to the membrane potential. To suggest new high-performance optical probes for membrane-potential imaging it is important to understand in detail the membrane-induced structural changes in the probe, the membrane association dynamics of the probe, and its membrane-specific optical properties. To contribute to this effort, we here study an optical probe, N-acetylaladanamide (NAAA), in the presence of a POPC lipid bilayer using a multiscale integrated approach to assess the probe structure, dynamics, and optical properties in its membrane-bound status and in water solvent. We find that the probe eventually assimilates into the membrane with a specific orientation where the hydrophobic part of the probe is buried inside the lipid bilayer, while the hydrophilic part is exposed to the water solvent. The computed absorption maximum is red-shifted when compared to the gas phase. The computations of the two-photon absorption and second harmonic generation cross sections of the NAAA probe in its membrane-bound state which is of its first kind in the literature suggest that this probe can be used for imaging the membrane potential using nonlinear optical microscopy. [ABSTRACT FROM AUTHOR]

An aggregate production-distribution model, which minimizes the regular, overtime and outsourced production costs along with inventory holding, backorder, hiring/laying-off and trip-wise distribution costs, is developed for a renowned bearing manufacturing industry in India. The proposed integer non-linear programming (INLP) problem is NP-hard and hence a discrete particle swarm optimization (DPSO) algorithm is applied to solve the multi-site, multi-period production-distribution problem. The results obtained using DPSO algorithm are compared with the results of memetic algorithm (MA), genetic algorithm (GA) and simulated annealing (SA). DPSO algorithm results are far superior to that of other meta-heuristic approaches for the problem considered. [ABSTRACT FROM AUTHOR]

Intensities of spin-forbidden transitions in electronic absorption and emission spectra of molecular oxygen are analyzed in order to understand the key mechanisms of spin-states mixing induced by spin-orbit coupling (SOC) and the ways to overcome spin prohibition for various photophysical and biochemical processes. Multireference configuration interaction calculations with SOC account are used to generalize spin-selection rules for the oxygen atmospheric and Herzberg bands in free O2 molecule and in collision complexes. Intensity enhancement of the atmospheric a1Δ g → X3Σ g−, b1Σ g+ → X3Σ g−, and Noxon b1Σ g+ → a1Δ g transitions upon bimolecular collisions are compared with those for Herzberg III transitions A′3Δ u ← X3Σ g−. Electric quadrupole, dipole, and magnetic approximations are used for transition probability calculations. Intensity distribution in rotational lines is also considered. With this background, we propose some simple spin-selection rules for dioxygen activation in enzymatic reactions. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]