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Present study investigates the stiffening effect on the behavior of tubular T-joints in offshore platform jacket structures subjected to axial compression. Stiffening is crucial to enhance the structures' strength and lifetime. Tubular cross section structures are preferred due to their mechanical properties and cost-efficiency. The study introduces an innovative technique by adding stiffeners at the interface between braces and chords to effectively distribute loads from multiple directions. The T-joint specimen used has specific dimensions: Chord length 400 mm, brace length 200 mm, chord diameter 100 mm, brace diameter 50 mm, chord thickness 4 mm, and brace thickness 3 mm. Experimental tests and Numerical simulations were conducted to measure failure loads for both stiffened and unstiffened T-joints. Stiffened configurations (4, 6, and 8 strips) has a notable impact on the ultimate capacity of the T-joint, showcasing an increase in strength compared to the unstiffened joint. Stiffened joints showed a significant increase in ultimate strength compared to unstiffened joints, with improvements ranging from 67.18 to 73.33% for different stiffener configurations. Joint local stiffness also improved substantially, with percentage increases ranging from 67.03 to 140.80% for various stiffener configurations. Present research work demonstrates the positive impact of stiffeners on tubular T-joints, improving their strength and stiffness while showing strong agreement between numerical simulations and experimental results and the study also concludes that the addition of stiffeners effectively enhances the ultimate capacity and local stiffness of tubular T-joints. These findings emphasize the effectiveness of the proposed reinforcement strategies for optimizing tubular T-joints in offshore structures.

ABSTRACTThe application of artificial neural network (ANN) to predict the wear rate of the surface composites produced using a solid-state technique called friction stir processing (FSP) is presented in this work. The copper surface composites were prepared by incorporating different sort of ceramic particles such as SiC, TiC, Al2O3, WC and B4C. The design of experiments (DOE) strategy was utilised to direct the experimental work. The considered operating parameters were sort of ceramic particle, traverse speed, tool rotational speed and groove width, whereas wear rate is the response. An approximation mechanism having an arbitrary function, the ANN was consequently used for simulating the wear rate of the surface composites. The feedforward back propagation technique was employed to alter the weights of the network to minimise the mean squared error for the development of ANN models. The predicted trends were explained and studied the influence of the considered factors with the aid of observed micro structures. The lower wear rate was observed with B4C-reinforced surface composites.

Wire arc additive manufacturing is a promising reliable free-form fabrication technique suitable for producing large-scale components that feature a very low buy-to-fly ratio. This research work is aimed to fabricate a rectangular prototype Inconel-625 alloy slab using a robotic metal inert gas welding system. The microstructure and mechanical properties of as-deposited and solution-annealed (SA) alloys were investigated. It was found that the as-deposited alloy exhibited a columnar dendritic structure and the presence of intermetallic phases such as the Laves phase, NbC and carbides were observed in the gamma-nickel matrix. In SA deposit, the intermetallic phases were dissolved in the NiCr-matrix and the secondary carbides M23C6, M6C were also observed in the microstructure. It was found that the ultimate tensile strength and microhardness of the as-deposited alloy were higher than that of SA deposit.

ABSTRACTWire arc additive manufacturing is a promising reliable free-form fabrication technique suitable for producing large-scale components that feature a very low buy-to-fly ratio. This research work is aimed to fabricate a rectangular prototype Inconel-625 alloy slab using a robotic metal inert gas welding system. The microstructure and mechanical properties of as-deposited and solution-annealed (SA) alloys were investigated. It was found that the as-deposited alloy exhibited a columnar dendritic structure and the presence of intermetallic phases such as the Laves phase, NbC and carbides were observed in the gamma-nickel matrix. In SA deposit, the intermetallic phases were dissolved in the NiCr-matrix and the secondary carbides M23C6, M6C were also observed in the microstructure. It was found that the ultimate tensile strength and microhardness of the as-deposited alloy were higher than that of SA deposit.

Monoamine oxidase B (MAO-B) is a potential biomarker for Parkinson’s disease (PD), a neurodegenerative disease associated with the loss of motor activities in human subjects. The disease state is associated with dopamine deprival, and so the inhibitors of MAO-B can serve as therapeutic drugs for PD. Since the expression level of MAO-B directly correlates to the disease progress, the distribution and population of this enzyme can be employed to monitor disease development. One of the approaches available for estimating the population is two-photon imaging. The ligands used for two-photon imaging should have high binding affinity and binding specificity toward MAO-B along with significant two-photon absorption cross sections when they are bound to the target. In this article, we study using a multiscale modeling approach, the binding affinity and spectroscopic properties (one- and two-photon absorption) of three (Flu1, Flu2, Flu3) of the currently available probes for monitoring the MAO-B level. We report that the binding affinity of the probes can be explained using the molecular size and binding cavity volume. The experimentally determined one-photon absorption spectrum is well reproduced by the employed QM/MM approaches, and the most accurate spectral shifts, on passing from one probe to another, are obtained at the coupled-cluster (CC2) level of theory. An important conclusion from this study is also the demonstration that intrinsic molecular two-photon absorption strengths (δ2PA) increase in the order δ2PA(Flu1) > δ2PA(Flu2) > δ2PA(Flu3). This is in contrast with experimental data, which predict similar values of two-photon absorption cross sections for Flu1 and Flu3. We demontrate, based on the results of electronic-structure calculations for Flu1 that this discrepancy cannot be explained by an explicit account for neighboring residues (which could lead to charge transfer between a probe and neighboring aromatic amino acids thus boosting δ2PA). In summary, we show that the employed multiscale approach not only can optimize two-photon absorption properties and verify binding affinity, but it can also help in detailed analyses of experimental data.

In this investigation, Friction stir welding (FSW) was performed to join 3 mm-thick AISI 321 stainless steel sheets. The rectangular sheets of size 100 mm × 50 mm were butt joined to contemplate the impact of tool rotational speeds for the steady welding traverse speed of 55 mm/min, axial force of 13 kN and tool tilt angle of 1.5°. The present assessment aims to correlate the relationship between the weld joint properties and important FSW parameter, the tool rotational speed. Microstructural investigation on the FS welded joints was performed using optical microscope and scanning electron microscopy (SEM). Transverse tensile test was undertaken to ascertain the quality and strength of the welded joints such as yield strength, ultimate tensile strength, etc. The microstructural features reveal evolution of fine equiaxed austenite grain structures in the weld stir zone dominated by discontinuous dynamic recrystallization mechanism. The weld joints fabricated at 500 rpm and 700 rpm had significantly better strength about 88% and 93% compared to the base metal. Subsequently, the hardness of the weld stir zones was significantly greater than the hardness of the base metal. All the welds fractured at a distance to that of the weld stir zone and dimple structures were observed at the fracture locations.

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 β-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 π–π 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.

Sirtuins are a family of nicotinamide adenine dinucleotide (NAD+)-dependent enzymes, which undergo robust deacetylase activity, resulting in the production of nicotinamide. It is well known that nicotinamide, which is one of the products, can also act as an inhibitor for further deacetylation process by forming NAD+again. Hence, the removal of nicotinamide from sirtuins is a demanding process, and the mechanistic understanding of the process remains elusive. In this investigation, we have made an attempt to unravel the unbinding pathways of nicotinamide from SIRT1, SIRT2, and SIRT3 (SIRT1–3) using Random Acceleration Molecular Dynamics (RAMD) Simulations, and we have successfully identified various unbinding channels. The selectivity of the egression channel is determined by using a thorough analysis of the frequency of egression trajectories. Similarly, various inhibitors have been docked with the active sites of SIRT1–3, and their egression pathways have been investigated to understand whether they follow the same egression pathway as that of nicotinamide. The residues that are responsible for the unbinding pathways have been determined from the analysis of RAMD trajectories. From these results, it is clear that phenylalanine and histidine residues play major roles in the egression of inhibitors. Additionally, the key residues Leu, Pro, Met, Phe, Tyr, and Ile are found to control the release by acting as gateway residues. The role of these residues from different egression channels has been studied by carrying out mutations with alanine residue. This is the first report on sirtuins, which demonstrates the novel unbinding pathways for nicotinamide/inhibitors. This work provides new insights for developing more promising SIRT1–3 inhibitors.

6-mm-thick pure copper and dual-phase brass plates were joined using friction stir welding (FSW). The role of plate location prior to welding and the tool rotational speed on the microstructure evolution was evaluated and correlated to the tensile properties of the joint. All the joints with copper on advancing side produced defects. Typical zones commonly found in FSW joints were observed. TMAZ was not found on the copper side, and no coarsening of grains was noticed in the HAZ on the brass side. The microstructure of the weld zone was heterogeneous and grouped into three categories. The plate position and the tool rotational speed influenced the material flow and the formation of different structures. The weld zone was further characterized by ultra-fine grains, dislocations and annealing twins. The hardness across the weld zone was varying considerably. The process parameter had an opposite effect on the hardness of brass and copper portion of the weld zone. The joints with brass on advancing side showed higher tensile strength. The fracture location and surfaces were further reported.

This work is focused on developing AA2124/4wt.%B4C nano-composite coatings on Ti−6Al−4V using friction surfacing to improve the wear resistance. The composite was produced using conventional stir casting method and coatings were laid using an indigenously-developed friction surfacing machine. The rotational speed of the mechtrode was varied. The microstructure of the composite coating was observed using conventional and advanced microscopic techniques. The sliding wear behavior was evaluated using a pin-on-disc apparatus. The coating geometry (thickness and width) increased with increased rotational speed. The interface was straight without thick intermetallic layer. Homogenous distribution of nano B4C particles and extremely fine grains was observed in the composite coating. The interfacial bonding between the aluminum matrix and B4C particles was excellent. The composite coating improved the wear resistance of the titanium alloy substrate due to the reduction in effective contact area, lower coefficient of friction and excellent interfacial bonding.

To address drug resistance to HIV-1 non-nucleoside reverse transcriptase inhibitors (NNRTIs), a series of novel diarylpyrimidine (DAPY) derivatives targeting “tolerant region I” and “tolerant region II” of the NNRTIs binding pocket (NNIBP) were designed utilizing a structure-guided scaffold-hopping strategy. The dihydrofuro[3,4-d]pyrimidine derivatives 13c2and 13c4proved to be exceptionally potent against a wide range of HIV-1 strains carrying single NNRTI-resistant mutations (EC50= 0.9–8.4 nM), which were remarkably superior to that of etravirine (ETV). Meanwhile, both compounds exhibited comparable activities with ETV toward the virus with double mutations F227L+V106A and K103N+Y181C. Furthermore, the most active compound 13c2showed favorable pharmacokinetic properties with an oral bioavailability of 30.96% and a half-life of 11.1 h, which suggested that 13c2is worth further investigation as a novel NNRTI to circumvent drug resistance.

Friction stir welding (FSW) was applied for the joining of 3-mm-thick AISI 316L stainless steel sheets. The investigation was aimed to explore the relationship between weld joint characteristics and one of the very important primary FSW parameters, the welding speed. The soundness of the fabricated joints was tested by x-ray radiography technique initially. The microstructural studies of the joints were carried out using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron back scattered diffraction (EBSD). Discontinuous dynamic recrystallization was the suggestive dominant recrystallization mechanism in the weld stir zone (SZ). The presence of fine equiaxed austenite grain boundaries and the consequent increase in hardness at the weld SZ resulted in joint strength superior to that of the base steel at higher welding speeds. But, at lower welding speeds, the evolution of delta ferrite decreased the toughness and strength of the joints owing to higher heat generation (higher peak temperature). However, the delta ferrite formed in the weld SZ has not transformed into sigma phase, probably due to fast cooling of the weld zone.

Understanding the mechanism of fibrillization of amyloid forming peptides could be useful for the development of therapeutics for Alzheimer’s disease (AD). Taking this standpoint, we have explored in this work the free energy profile for the interconversion of monomeric and dimeric forms of amyloid forming peptides into different secondary structures namely beta-sheet, helix, and random coil in aqueous solution using umbrella sampling simulations and density functional theory calculations. We show that the helical structures of amyloid peptides can form β sheet rich aggregates through random coil conformations in aqueous condition. Recent experiments (Chem. Eur. J.2018, 24, 3397–3402 and ACS Appl. Mater. Interfaces2017, 9, 21116–21123) show that molybdenum disulfide nanosurface and nanoparticles can reduce the fibrillization process of amyloid beta peptides. We have unravelled the free energy profile for the interconversion of helical forms of amyloid forming peptides into beta-sheet and random coil in the presence of a two-dimensional nanosurface of MoS2. Results indicate that the monomer and dimeric forms of the peptides adopt the random coil conformation in the presence of MoS2while the helical form is preferable for the monomeric form and that the beta-sheet and helix forms are the preferable forms for dimers in aqueous solution. This is due to strong interaction with MoS2and intramolecular hydrogen bonds of random coil conformation. The stabilization of random coil conformation does not lead to a β sheet like secondary structure for the aggregate. Thus, the confinement of MoS2promotes deaggregation of amyloid beta peptides rather than aggregation, something that could be useful for the development of therapeutics for AD.

The widespread interest in phase recognition of lipid membranes has led to the use of different optical techniques to enable differentiation of healthy and not fully functional cells. In this work, we show how the combination of different (non)linear optical methods such as one-photon absorption (OPA), two-photon absorption (TPA), and second harmonic generation (SHG) as well as the study of the fluorescence decay time leads to an enhanced screening of membrane phases using a fluorescent 1,1′-dioctadecyl-3,3,3′,3′-tetramethylindocarbocyanine (DiD) probe. In the current study we consider the pure liquid disordered phases of DOPC (dioleoyl-sn-glycero-3-phosphocholine, room temperature) and DPPC (1,2-dipalmitoyl-sn-glycero-3-phosphocholine, 323 K), the solid gel phase of DPPC (298 K), and the liquid ordered phase of a 2:1 binary mixture of sphingomyelin and cholesterol. By means of extensive hybrid quantum mechanics–molecular mechanics calculations and based upon the (non)linear absorption of the embedded probes, it is found that DiD can be used to identify the lipid bilayer phase. The joint TPA and SHG as well as fluorescence analyses qualifies DiD as a versatile probe for phase recognition. In particular, the SHG data obtained by means of hyper-Rayleigh scattering and by electric field induced second harmonic generation reveal differences in polarization of the probe in the different environments. The TPA results finally confirm the particular location of the probe in between the polar headgroup region of the 2:1 SM:Chol mixture in the liquid ordered phase.

The social network, by the name which has popularised in today's world and growing rapidly at all times and controlling over mankind. The social networks like Twitter, Facebook, and LinkedIn, etc., have become a regular and daily usage of many people. It becomes a good mediator for the people who would like to share some posts, are some of their own videos, or some messages. But there has been major issues that the particular user of the social networks like Twitter and Facebook have the problem of indiscipline actions which we call as spam, by the third person who is knowingly doing this to spoil their intention and good opinion upon each other. Also, these spams help to steal information about the people who using social networks. In this paper, we study and analyse about the spam in social networks and machine learning algorithms to detect such kind of spams. This paper also focuses on the ML algorithms detection rate and false positive rate over different datasets.

Friction stir welding (FSW) is one of the new technique for welding materials in solid state welding process. In this proposed work we are using FSW to join the two dissimilar alloys of aluminium. The 6mm thick aluminum plates of aluminium 5086 and aluminum 7075 plates are considered for welding. These have been considered due to their application in various fields. In this experimental process Taguchi’s L9 orthogonal array method is used for optimizing the three process parameters namely rotational speed, axial force and welding speed. To produce a better joint the tensile strength is predicted for the optimum welding parameters and also their percentage of contribution is calculated, by applying the effect of analysis of variance. Depends upon the experimental study, the rotational speed is found better over the other process parameters, which enhances the quality of the weld. The tensile strength has been found for the optimum parameters and the result found during the experiment was 290Mpa which was higher than the base metal strength of aluminium 5086 alloy. The SEM fractograph analysis was done on the optimum parameters welded joints to show the fracture behaviour of tensile test which justifies the visual inspection results of brittle and ductile failures.

The fluorescent marker Laurdan and its new derivative, C-Laurdan, have been investigated by means of theoretical calculations in a DOPC lipid bilayer membrane at room temperature, and a comparison is made with results from fluorescence experiments. Experimentally, the latter probe is known to have a higher sensitivity to the membrane polarity at the lipid headgroup region and has higher water solubility. Results from Molecular Dynamics (MD) simulations show that C-Laurdan is oriented with the carboxyl group toward the head of the membrane, with an angle of 50° between the molecular backbone and the normal to the bilayer, in contrast to the orientation of the Laurdan headgroup whose carbonyl group is oriented toward the polar regions of the membrane and which describes an angle of ca. 70–80° with the membrane normal. This contrast in orientation reflects the differences in transition dipole moment between the two probes and, in turn, the optical properties. QM/MM results of the probes show little differences for one- (OPA) and two-photon absorption (TPA) spectra, while the second harmonic generation (SHG) beta component is twice as large in Laurdan with respect to C-Laurdan probe. The fluorescence anisotropy decay analysis of the first excited state confirms that Laurdan has more rotational freedom in the DOPC membrane, while C-Laurdan experiences a higher hindrance, making it a better probe for lipid membrane phase recognition.

Friction stir back extrusion (FSBE) is emerging as a novel method to produce high strength fine grained metallic tubes. The objective of the present work is to produce aluminum seamless tubes from solid cylindrical bars using FSBE and to report the microstructure and mechanical characterization. A die, tool and fixture were designed to carry out FSBE. A conventional friction stir welding machine was utilized for FSBE. A cylindrical bar of aluminum alloy AA6061-T6 was kept inside the hole in the die and extruded by plunging the rotating tool. The microstructure of the produced tube was studied using optical microscopy. The microstructure was found to be homogeneous along the tube. The microhardness and compressive strength of the tube have been presented in this paper. The results indicated that the FSBE process was capable of producing sound aluminum seamless tubes.

The design of novel fibril imaging molecules for medical diagnosis requires the simultaneous optimization of fibril-specific optical properties and binding specificity toward amyloid fibrils. Because of the possibility to monitor internal organs and deep tissues, the two-photon probes that can absorb in the infrared (IR) and near-IR (NIR) region with a significant two-photon absorption cross section are of immense interest. To contribute to this exploration of chemical compounds suitable for two-photon fibril imaging, we have computationally studied the one- and two-photon properties of a donor–acceptor-substituted DANIR-2c probe, which was used for in vivo detection of β-amyloid deposits using fluorescence spectroscopy. In particular, a multiscale computational approach was employed involving molecular docking, molecular dynamics, hybrid QM/MM molecular dynamics, and coupled-cluster/MM to study the binding of the studied probe to amyloid fibril and its one- and two-photon absorption properties in the fibrillar environment. Multiple binding sites are available for this probe in amyloid fibril, and the one corresponding to the largest binding affinity exhibits also the largest and experimentally meaningful two-photon absorption cross section, thus demonstrating the potential of the studied probe in two-photon microscopy.

Friction stir welding provides an alternative method of joining aluminum in a reliable way. Anticipation of the joint efficiency is then a necessary step to optimize the process of the welding operation. In the light of this, artificial neural network (ANN) technique may then be applied as a reliable method for simulating and predicting the durability of the joints for different process parameters. In the present work, an ANN model is presented that predicts the ultimate tensile strength of friction stir-welded dissimilar aluminum alloy joints. Four parameters were considered including tool pin profile (straight square, tapered square, straight hexagon, straight octagon and tapered octagon), rotational speed, welding speed and axial force. Experimental tests were conducted according to a four-parameter five level central composite design. A feed-forward back propagation ANN with a single hidden layer comprising 20 neurons was employed to simulate the ultimate tensile strength (UTS) of the joints. The neural network was trained using the data obtained from the experimental work. A comparison between the experimental and simulated data showed that the ANN model reliably predicted the UTS of dissimilar aluminum alloy friction stir-welded joints. The models developed were capable of predicting values with less than 5 % error. Furthermore, the effect of different process parameters on the tensile behavior of dissimilar joints was also investigated and reported upon.

The extraordinary ligand binding properties of albumin makes it a key player in the pharmacokinetics and pharmacodynamics of many vital drugs. Albumin is highly susceptible for nonenzymatic glycation mediated structural modifications, and there is a need to determine structural and functional impact of specific AGEs modifications. The present study was aimed toward determining the AGE mediated structure and function changes, primarily looking into the effect on binding affinity of drugs in the two major drug binding sites of albumin. The impact of the two most predominant AGEs modifications, i.e., carboxyethyllysine (CEL) and argpyrimidine (Arg-P), was studied on the basis of the combination of in vitroand in silicoexperiments. In vitrostudies were carried out by AGEs modification of bovine serum albumin (BSA) for the formation of Arg-P and CEL followed by drug interaction studies. In silicostudies involved molecular dynamics (MD) simulations and docking studies for native and AGEs modified BSAs. In particular the side chain modification was specifically carried out for the residues in the drug binding sites, i.e., Arg-194, Arg-196, Arg-198, and Arg-217, and Lys-204 (site I) and Arg-409 and Lys-413 (site II). The equilibrated structures of native BSA (n-BSA) and glycated BSA (G-BSA) as obtained from MD were used for drug binding studies using molecular docking approach. It was evident from the results of both in vitroand in silicodrug interaction studies that AGEs modification results in the reduced drug binding affinity for tolbutamide (TLB) and ibuprofen (IBP) in sites I and II. Moreover, the AGEs modification mediated conformational changes resulted in the shallow binding pockets with reduced accessibility for drugs.