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While nanocatalysis is fascinating, our understanding of the issues related to nanocatalysts, such as surface restructuring and induction time, is still in its infancy. If a nanocatalyst is made in such a way that it performs its role as a nanocatalyst and at the same time provides information about its surroundings through a suitable optical output signal, it is anticipated that several insights into the catalytic mechanisms will emerge. These insights, in turn, can facilitate the design of more effective nanocatalysts. With an aim to understand this, two types of fluorescent Cu-based nanocatalysts, tannic acid (TA-CuNCs) and cysteine-capped (Cys-CuNCs), have been synthesized, and their catalytic performance in the reduction of 4-nitrophenol (4-NP) to 4-aminophenol has been investigated. Along with the usual analytical methods, the fluorescence property of the nanocatalysts has also been exploited to extract relevant information on the catalytic reaction. The data have also been compared with ligand-free CuNCs. Kinetic data obtained from absorption studies have revealed that the rate constants for the nanocatalyst-catalyzed reaction follow the order: kTA–CuNCs> kCuNCs> kCys–CuNCs. Quite interestingly, it has been observed that unlike TA-CuNCs, Cys-CuNCs, and ligand-free CuNCs exhibit an induction time in the catalytic reaction, indicating the crucial role of ligand-mediated surface restructuring. Furthermore, it has been found that eliminating dissolved oxygen from the reaction medium increases the rate constants and eliminates the induction time. This finding has essentially indicated the influence of dissolved oxygen on facilitating the reverse oxidation of 4-nitrosophenol (an intermediate) to 4-aminophenol. It has also been observed that the catalytic activity decreases with an increase in 4-NP concentration, suggesting a Langmuir–Hinshelwood mechanism for the event. The outcome of the present work sheds light on the role of surface ligands in nanocatalysis and presents new opportunities for designing new nanocatalysts for practical applications.

An inorganic–organic nanohybrid material comprising an inorganic exciton (CdTe@ZnS) and an organic exciton (J-aggregates) has been synthesized, and subsequently investigations on exciton–exciton coupling between two components of the materials are carried out by employing various spectroscopic techniques. Analysis of the data has revealed very high Förster-type resonance energy transfer (FRET) from the donor quantum dots (QDs) to the acceptor J-aggregates. Interestingly, a clear splitting of the QD emission band during the FRET event is observed, indicating efficient coupling between inorganic and organic excitons. The observation of valley splitting of QD emission by organic J-aggregates, even in the absence of an external field, is new and exciting. More interestingly, the investigations have also shown that the valley splitting of the QD emission can be controlled by regulating the FRET process. In fact, a linear relationship between the energy separation value of the valley splitting and the FRET efficiency between QDs and J-aggregates is obtained. Moreover, in the present hybrid system, the presence of an organic moiety becomes advantageous in the sense that the valley splitting can also be controlled easily through chemical modification of the organic moiety. The outcome of the present investigation essentially demonstrates that the present nanohybrid system can be considered as a potential candidate for the fabrication of valleytronic materials.

The present paper aims at theoretical development of a strain gauge-based methodology for accurate determination of notch stress intensity factor (NSIF) in sharp center V-notched tensile configuration (CENT). In line with Dally-Sanford's single strain gauge technique for determination of stress intensity factor (SIF) in cracked configuration, theoretical formulations have first been developed for single edge notch tensile (SENT) specimen and the same is applied to CENT by making necessary changes. Efficacy of the theoretical formulations developed has been investigated by carrying out finite element (FE) simulation in extracting NSIF for CENT. Results from FE simulations show that the theoretical formulations developed could correctly guide in accurate extraction of NSIF from the strain gauge readings in the case of CENT. In addition, it was also observed that the bounds on the strain gauge location put forward by the present formulation has an important bearing on accuracy of extracted NSIF. Placing strain gauges within and outside the upper bound results in highly accurate (<5%) and highly erroneous (>30%) values of NSIF respectively.

The present paper investigates the dynamic responses and associated damage of GLARE 5–2/1 plates subjected to successive repeated low-velocity impacts (LVIs) by spherical impactors having varied masses. For low-energy LVIs characterized by surface dents on the outer aluminium layer, the progression of damage of the internal plies is evaluated by incorporating a continuum damage model based on Hashin’s criteria considering the in situ 3D stress state. For the present analysis, a 3D finite element code is implemented to obtain the dynamic responses of the target GLARE plate by incorporating the Newmark-β method and Hertzian contact law, considering the effect of local indentation on the contact stiffness. Results show that the impactor mass, the impact energy divisions and their order of occurrence significantly influence the indentation at the impact site, thereby affecting the dynamic responses and the damage sustained by the GLARE plates. Results also show that the indentation post the first impact leads to an increase in the local stiffness at the impact site of GLARE, though the same does not indicate the absence of internal damage.

Visible light-mediated photoredox catalysis has emerged to be a fascinating approach for the activation of CO2and its subsequent fixation into valuable chemicals utilizing renewable and inexhaustible solar energy. Although great progress has been made in CO2photoreduction, visible light-assisted organic synthesis using CO2as a reactive substrate is rarely explored. Herein, we report an efficient, facile, and economically viable photoredox-mediated approach for the synthesis of important β-thioacids via carboxylation of olefins with CO2and thiols over a porous functionalized metal–organic framework (MOF), Fe-MIL-101-NH2, as a photocatalyst under ambient conditions. This multicomponent reaction offers wide substrate scope, mild reaction conditions, easy work-up, cost-effective and reusable photocatalysts, and higher product selectivity. Computational studies suggested that CO2interacts with the thiophenol–styrene adduct to facilitate the synthesis of β-thioacids in almost quantitative yields.

Although in recent times nanoparticles (NPs) are being used in various biological applications, their mechanism of binding interactions still remains hazy. Usually, the binding mechanism is perceived to be mediated through either the protein corona (PC) or protein complex (PCx). Herein, we report that the nanoparticle (NP)–protein interaction can also proceed via a different pathway without forming the commonly observed PC or PCx. In the present study, the NP–protein interaction between less-toxic zinc–silver–indium-sulfide (ZAIS) quantum dots (QDs) and bovine serum albumin (BSA) was investigated by employing spectroscopic and microscopic techniques. Although the analyses of data obtained from fluorescence and thermodynamic studies do indicate the binding between QDs and BSA, they do not provide clear experimental evidence in favor of PC or PCx. Quite interestingly, high-resolution transmission electron microscopy (HRTEM) studies have shown the formation of a new type of species where BSA protein molecules are adsorbed onto some portion of a QD surface rather than the entire surface. To the best of our knowledge, we believe that this is the first direct experimental evidence in favor of a model-free pathway for NP–protein interaction events. Thus, the outcome of the present study, through experimental evidence, clearly suggests that NP–protein interaction can proceed by following a pathway that is different from classical PC and PCx.

A 52-year-old lady with hypertrophic obstructive cardiomyopathy, atrial flutter, and old right hemispheric stroke in the background underwent implantable cardioverter-defibrillator implantation for complete heart block. She was yet to start her regular anticoagulant and presented to hospital emergency with acute right middle cerebral artery (MCA) territory stroke (NIH Stroke Scale/Score of 14). After ruling out absolute contraindications, she was given intravenous thrombolysis (did not have a blood vessel target for endovascular therapy). Post thrombolysis, she had clot mobilization from the internal carotid artery to the MCA and systemic embolization to kidneys and lower limbs. The patient underwent an urgent embolectomy and lower limbs were saved from amputation. Our case highlights the importance of checking peripheral pulses in acute stroke patients post thrombolysis. Though the patient had initial deterioration after thrombolysis, she gradually improved and later achieved satisfactory modified Rankin scale underscoring the ultimate potential benefits of thrombolysis in acute stroke. There is a high chance of thrombus formation in patients with atrial flutter who undergo recent cardiac procedure especially if they are off anticoagulation for even a short period. Hence, unnecessary apprehension of anticoagulant use in proper situations may create life-threatening complications.

The limited stock of classical nonrenewable energy sources has motivated researchers to explore efficient strategies for sustainable and renewable energy production. Hydrogen production via electrochemical water splitting is one of the key solutions that can meet this demand. Today 3d transition metal based nanomaterials offer a huge opportunity in the hydrogen evolution reaction (HER) via electrochemical water splitting. Herein, we report an easy and convenient synthesis route for designing the novel tetradentate phosphonate ligand based metal–organic framework (MOF, H8L-Co-crystal). The material has been characterized by single crystal X-ray diffraction (SXRD), powder XRD, thermogravimetric analysis, scanning electron microscopy, and Fourier transform infrared spectroscopy, and explored in the HER from various mediums including seawater. This single crystal belongs to the monoclinic phase having C2/cspace group, with unit cell parameters a= 29.364(8) (Å), b= 12.204(4) (Å), c= 9.925(3) (Å), α = 90° = γ, β = 97.405° (CCDC no. 1922964) and the unit cell volume = 3527.04 Å3. The material H8L-Co-crystal shows very good catalytic activity towards H2evolution with a low overpotential of 243 mV at a current density 10 mA/cm2as well as a low Tafel slope of 102 mV/dec in acidic medium, which is comparable to commercial HER catalysts, and one of the best among non-postsynthetically modified MOFs. The electrochemical active surface area (ECSA) data have been measured to explain the high hydrogen evolution rate in different mediums. Density functional theory (DFT) study based on first-principle calculations provides a very useful understanding about the structure–catalytic property relationship and reveals the role of surface active sites toward electrochemical HER.

With an aim to understand the interaction mechanism of bovine serum albumin (BSA) with copper nanoclusters (CuNCs), three different types CuNCs having chemically different surface ligands, namely, tannic acid (TA), chitosan, and cysteine (Cys), have been fabricated, and investigations are carried out in the absence and presence of protein (BSA) at ensemble-averaged and single-molecule levels. The CuNCs, capped with different surface ligands, are consciously chosen so that the role of surface ligands in the overall protein–NCs interactions is clearly understood, but, more importantly, to find whether these CuNCs can interact with protein in a new pathway without forming the “protein corona”, which otherwise has been observed in relatively larger nanoparticles when they are exposed to biological fluids. Analysis of the data obtained from fluorescence, ζ-potential, and ITC measurements has clearly indicated that the BSA protein in the presence of CuNCs does not attain the binding stoichiometry (BSA/CuNCs > 1) that is required for the formation of “protein corona”. This conclusion is further substantiated by the outcome of the fluorescence correlation spectroscopy (FCS) study. Further analysis of data and thermodynamic calculations have revealed that the surface ligands of the CuNCs play an important role in the protein–NCs binding events, and they can alter the mode and thermodynamics of the process. Specifically, the data have demonstrated that the binding of BSA with TA-CuNCs and Chitosan-CuNCs follows two types of binding modes; however, the same with Cys-CuNCs goes through only one type of binding mode. Circular dichroism (CD) measurements have indicated that the basic structure of BSA remains almost unaltered in the presence of CuNCs. The outcome of the present study is expected to encourage and enable better application of NCs in biological applications.

The development of an efficient and robust material for adsorptive removal of highly toxic metals like mercury from water resources is very challenging from the perspectives of hygiene and sustainable environment. Heteroatoms such as sulfur and nitrogen in this high surface area porous organic polymer is very promising for mercury remediation because it offers strong interactions between Hg(ii) ions and S/N bound at the pore surface of the adsorbent. Thus, herein we developed a new secondary amine-linked, sulfur-containing and N-rich porous organic polymer, TTP-1, viapolycondensation of a tetrapodal amine and thiophene-2-carbaldehyde. TTP-1 displayed a high BET surface area of 1034 m2g−1with hierarchical porosity and exceptionally high uptakes of 3106 and 691 mg g−1for inorganic Hg2+and organic methylmercury (CH3Hg+), respectively. The high adsorption efficiency for mercury capture is also supported from the strong noncovalent interaction of the ligand S and N lone pairs with Hg2+, as revealed from the ab initioquantum chemical calculation and AIM analysis. Cost-effective, eco-friendly and scaleable synthesis of porous organic polymer with hierarchical porosity reported herein may contribute to the design of a benchmark adsorbent for the remediation of mercury (Hg(ii)/CH3Hg+) and may significantly aid in industrial and environmental cleanup.

Nerinetide, an eicosapeptide that interferes with post-synaptic density protein 95, is a neuroprotectant that is effective in preclinical stroke models of ischaemia-reperfusion. In this trial, we assessed the efficacy and safety of nerinetide in human ischaemia-reperfusion that occurs with rapid endovascular thrombectomy in patients who had an acute ischaemic stroke.

Free vibration analysis of functionally graded (FG) non-spinning simply supported shaft having a transverse surface crack has been carried out. Material properties of the FG shaft are assumed to be graded radially following the power law of material gradation. Local flexibility coefficients as a function of depth of crack are computed with the help of Paris’ equation along with Castigliano’s theorem. Finite element (FE) formulation has been done using Timoshenko beam elements with two nodes and having four degrees of freedom per node. Based on the formulation, FE analysis has been performed to understand the effects of shaft’s slenderness, crack’s depth and location, gradient parameter and thermal gradient on the free vibration response of the cracked FG shaft. FE analysis show that for a cracked FG shaft, both gradation parameter and crack parameters have significant influence on the free vibration response. Gradation parameter could be suitably chosen in the design of FG shafts so as to minimize the increase in flexibility due to appearance of cracks.

A large number of scientific investigations are needed for developing a sustainable solid sorbent material for precombustion CO2capture in the integrated gasification combined cycle (IGCC) that is accountable for the industrial coproduction of hydrogen and electricity. Keeping in mind the industrially relevant conditions (high pressure, high temperature, and humidity) as well as good CO2/H2selectivity, we explored a series of sorbent materials. An all-rounder player in this game is the porous organic polymers (POPs) that are thermally and chemically stable, easily scalable, and precisely tunable. In the present investigation, we successfully synthesized two nitrogen-rich POPs by extended Schiff-base condensation reactions. Among these two porous polymers, TBAL-POP-2exhibits high CO2uptake capacity at 30 bar pressure (57.2, 18.7, and 15.9 mmol g–1at 273, 298, and 313 K temperatures, respectively). CO2/H2selectivities of TBAL-POP-1and 2at 25 °C are 434.35 and 477.93, respectively. On the other hand, at 313 K the CO2/H2selectivities of TBAL-POP-1and 2are 296.92 and 421.58, respectively. Another important feature to win the race in the search of good sorbents is CO2capture capacity at room temperature, which is very high for TBAL-POP-2(15.61 mmol g–1at 298 K for 30 to 1 bar pressure swing). High BET surface area and good mesopore volume along with a large nitrogen content in the framework make TBAL-POP-2an excellent sorbent material for precombustion CO2capture and H2purification.

In fibre reinforced polymer (FRP) composite laminates subjected to low velocity impact, one of the common mode of failure is ply breakage followed by interfacial delamination at the site of ply break. Improving the delamination resistance at the interface is therefore important and the present work examines quantitative understanding of how the addition of CNTs to epoxy might enhance the resistance to such delamination at the interface. A laminate made of plies with CNT-epoxy as the matrix and carbon fibre as the reinforcement has been considered to be broken through the full width. A full three dimensional FE analysis was carried out for such a carbon/CNT-epoxy laminate for different wt% of CNTs. Resistance to delamination has been assessed by computing critical strain energy release rate (Gc) using quadratic stress criterion (QSC) and virtual crack closure integral (VCCI). From the results, by adding CNTs to epoxy, a significant improvement in the delamination resistance could be observed. However, the improvement is till a certain specific CNT wt% and adding CNTs further leads to a significant reduction in delamination resistance. In addition, the effect of various factors such as fiber orientation of the adjacent continuous ply and resin layer thickness on critical strain energy release rate (Gc) have been studied. The results show that Gcalso depends upon the fiber orientation of the adjacent ply and on the resin layer thickness. As the resin layer thickness increases, a significant increase in Gcis observed.

The present paper describes the development of a genetic algorithm (GA) based methodology for determination of optimal number of actuators and their locations in smart fiber reinforced polymer composite shell structures. Finite element (FE) based state space representation of the system has been used to determine the optimal placement of actuators in order to maximize the controllability. Spillover from residual modes has also been considered while maximizing controllability. Even though the developed methodology needs a large computational time, it will be useful in off-line determination of optimal actuators locations in large structures.

The accuracy of measurement of opening mode stress intensity factor using strain gage techniques mainly depends on location of the strain gages. The present work proposes a finite element based simple procedure for accurate determination of three parameter zone and optimum strain gage location for various eccentric cracked configurations. In this paper, the effect of specimen size and crack length to width of the eccentric cracked plate on optimum location of strain gage is also studied. The results of the present investigation show that specimen size and ratio of crack length to width of the plate strongly influence the optimum location of strain gage.

We report a Ni-MOF(nickel metal–organic framework), Ni-SIP-BPY, synthesized by using two linkers 5-sulfoisophthalic acid (SIP) and 4,4′-bipyridine (BPY) simultaneously. It displays an orthorhombic crystal system with the Ama2 space group: a= 31.425 Å, b= 19.524 Å, c= 11.2074 Å, α = 90°, β = 90°, γ = 90°, and two different types of nickel(II) centers. Interestingly, Ni-SIP-BPYexhibits excellent sensitivity (limit of detection, 87 ppb) and selectivity toward the 2,4,6-trinitrophenol (TNP)-like mutagenic environmental toxin in the pool of its other congeners via“turn-off” fluorescence response by the synergism of resonance energy transfer, photoinduced electron transfer, intermolecular charge transfer, π–π interactions, and competitive absorption processes. Experimental studies along with corroborated theoretical experimentation, videdensity functional theory studies, shed light on determining the plausible mechanistic pathway in selective TNP detection, which is highly beneficial in the context of homeland security perspective. Along with the sensing of nitroaromatic explosives, the moderately low band gap and the n-type semiconducting behavior of Ni-SIP-BPYmake it suitable as a photoanode material for visible-light-driven water splitting. Highly active surface functionalities and sufficient conduction band minima effectively reduce the water and result in a seven times higher photocurrent density under visible-light illumination.

Bamboo fibers in the form of strips and dust were treated with NaOH solution of varying concentration (10, 15, and 20%). These treated and untreated samples were then subjected to FTIR and morphological studies. Again XRD study was carried out on those treated and untreated bamboo samples in both strip and dust form. It was found that during alkali treatment a lattice transformation from cellulose‐I to cellulose‐II took place. It is observed from IR index value that the conversion is maximum in between 15 and 20% of alkali treatment. Swelling in NaOH introduces considerable changes in crystallinity, orientation angle, etc. Degree of crystallinity and crystallinity index for bamboo strips increases with increasing treatment concentration of alkali and falls off after 15% alkali concentration. This is also supported by d‐spacing value. Orientation factor fx was calculated from the FWHM and it was found that fx value has been increased from 0.9879 to 0.9915 for 15% alkali treated and again lowered to 0.8522 for 50% alkali treated samples. Same observation of X‐ray study was obtained for dust samples but at an earlier concentration. Morphological study of bamboo dust with scanning electron microscope indicates fibrillation at higher alkali concentration. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5050–5056, 2006

The effect of blending poly(ethyl acrylate) and poly(butyl acrylate) in various proportions with suitably stabilized and plasticized polyvinyl chloride (PVC) was studied with reference to their physical, mechanical, thermal, and morphological properties. The tensile modulus and ultimate tensile strength indicated a rise initially, followed by their steady decrease with increasing concentration of the polyalkyl acrylates. A corresponding behavior of elongation at break and toughness are exhibited. The various polyblends exhibit thermal stability over unmodified PVC, as reflected from their thermomechanical studies, in which the penetration is also inversely related to the respective moduli. The biphasic cocontinuous systems as explicit from the morphological studies support phase mixing at the initial stages, with subsequent phasing‐out tendency, with increasing percentage of polyalkyl acrylate incorporation. The thermomechanical parameters are in conformity to their mechanical parameters, which have been further supported by their morphological studies. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3698–3703, 2006

Bamboo fibers that have been treated in NaOH solutions of varying concentrations were subjected to differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA) studies, respectively. The moisture desorption peak (and the enthalpy values associated with it) was moved to higher values as the alkali concentration increased up to 15% and shifted to lower values beyond that temperature. A broad exotherm was observed in all of the DSC curves for alkali treatments up to 15%. Beyond that concentration, two comparatively smaller exothermic peaks appeared for the 20% and 50% alkali-treated samples. DMTA study of bamboo strip samples reveals that the room-temperature value for the storage modulus (E‘) of the untreated bamboo strips is increased by ∼400% in the case of 15% alkali-treated samples, and the rate of decrease in the modulus over the temperature range of 140−180 °C is also maximum for those samples. The untreated bamboo samples show a primary loss modulus (E‘ ‘) peak at 111.8 °C, which is shifted to higher temperatures for alkali-treated samples. The damping parameter (tan ) is also maximum for untreated samples.

Bamboo strip reinforced novolac resin composites were fabricated using bamboo strips that were treated with varying concentrations of sodium hydroxide solution at a constant filler loading (25%). The mechanical properties of various composites (flexural modulus, toughness, tensile strength, and elastic modulus) were determined. The physical characteristics, such as the wetting ability of the alkali treated reinforcements, were increased because of alkali treatment. With increasing concentrations of alkali, a higher percent loss in weight occurred. The mechanical properties were increased with increasing mercerizing strength. Maximum improvement in properties was achieved with 16–20% of caustic treated reinforcements. An FTIR study indicated aryl alkyl ether formation with &bond;OH groups of cellulose and methylol groups of novolac resin. Beyond 20% there was degradation in all strength properties because of the failure in the mechanical properties of the reinforcements. A correlation was found to exist between the mechanical properties and the developed morphology. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100:238–244, 2006

Blends and full IPNs' of poly(vinyl chloride) and polybutylmethacrylate (PBMA) have been synthesized and characterized with respect to their mechanical, thermomechanical, and morphological properties. Both the systems displayed a rise in the modulus and ultimate tensile strength and a consequent decreasing tendency of elongation at break and toughness are exhibited. The influence of crosslinking of the two polymers as has been done in case of full IPNs over the ordinary blends is quite well understood from these properties. The thermomechanical analysis revealed a substantial rise in stability with increasing methacrylate concentration in the system and this is quite apparent from the softening characteristics of the different samples under study. The biphasic cocontinuous systems as explicit from the morphological studies support phase mixing at the initial stages, with subsequent phasing out tendency with increasing percentage of PBMA incorporation. The thermomechanical parameters are in conformity to their mechanicals which have been further supported by their morphological studies. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006

Semi1 and semi2 interpenetrating polymer networks (IPNs) of PVC and in situ formed PMMA have been synthesized using diallyl phthalate and ethylene glycol dimethacrylate as the crosslinkers of PVC and PMMA, respectively. These two types of IPNs have been compared w.r.t their physical, mechanical, and thermal properties and an endeavor has been made to find a correlation of these properties with the morphology generated in these systems. The semi1 IPNs displayed a decrease in their mechanical parameters and the physical properties as well, while in contrast, the semi2 IPNs exhibited a marginal increase in the corresponding values after an initial drop upto about 15% of crosslinked PMMA incorporation when compared to the crosslinked PVC in the case of semi1 IPN and linear PVC in the case of semi2 IPN. The various samples of semi1 and semi2 IPNs showed a two‐stage degradation typical of PVC, while confirming the increased stability with the samples having higher percentages of PMMA. The influence of crosslinking of the major matrix in semi1 IPN was almost counterbalanced by the influence of crosslinking in the dispersed PMMA phase in the case of semi2 IPN. The softening characteristics as detected by the extent of penetration of the probe, as has been detected by thermomechanical analysis, are in conformity with their mechanicals. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1725–1735, 2005

The effect of blending poly (methyl methacrylate) (PMMA) in various proportions with suitably stabilized and plasticized poly (vinyl chloride) (PVC) was studied with reference to their physical, mechanical, and thermal properties. The resulting morphologies of the various blends were also studied to find a suitable explanation of these properties. The physical and mechanical properties of such polyblends revealed a substantial increase in toughness accompanied with unusual increase in modulus and ultimate tensile strength after an initial drop at the initial stages of PMMA incorporation compared to pure reference compound PVC. The toughening effect, however, undergoes a reduction with increasing proportion of PMMA but it never goes below that of pure PVC (reference compound) within the ranges of PMMA incorporation under study. The various polyblends exhibit the two‐stage degradation typical of PVC and all of them possess higher thermal stability as manifested in their characteristic thermograms. The softening characteristics imparted by PMMA were also reflected in their respective TMA curves. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2721–2730, 2004

The present study examines the delamination initiation at the interface of broken and continuous plies in case of GR/E and GL/E laminates with broken central plies. A full 3D FE analysis has been performed with each layer of the laminate modelled as homogenous and orthotropic. The interface between the broken and continuous plies has been modelled with a thin resin rich layer. Eight-noded isoparametric layered elements have been used to model the laminate specimen. Also, 3D contact elements are used to prevent the interpenetration of delaminated faces at the interface. Based on the results of 3D FE analysis, GI, GI, and GI,, have been calculated at the delamination front using Irwin's Crack Closer Integral. It has been observed that the delamination initiation is a mixed mode phenomenon even in the case of uniaxial loading. Brewer and Lagace's Quadratic Stress Criterion has been used in conjunction with Linear Elastic Fracture Mechanics (LEFM) to calculate the delamination initiation strain and the critical strain energy release rate (Gc). The effects of various factors such as ply thickness, fiber orientation, resin stiffness on Gc have been studied for GR/E and GL/E laminates having broken central plies.

Ply breakage in laminated composites may be caused by impact load. Delamination usually precedes the failure of such broken ply laminates and it occurs at the interface of the broken and continuous plies. In the present work, an attempt has been made to find out the delamination initiation stress as well as critical strain energy release rate (Gc) for unidirectional [00] GL/E and GR/E laminates having one or more central ply/plies broken. Prediction of delamination initiation stress was attempted using "Quadratic Stress Criterion" and critical energy release for delamination has been assessed using LEFM in conjunction with a 3 D FE analysis.

Even though perovskite nanocrystals (PNCs) are quite attractive for optoelectronic applications, issues such as the low photoluminescence quantum yield (PLQY) and poor chemical stability of PNCs still remain formidable challenges that need to be tackled. Because ionic liquids (ILs) possess some interesting physicochemical properties, the present study is undertaken to find out the suitability of ILs in obtaining stable and defect-free PNCs. To explore this possibility, the interaction of ILs with PNCs has been investigated by both spectroscopy and microscopy. Studies have demonstrated that a significant enhancement in the PLQY of PNCs can be obtained by postsynthetic treatment of PNCs with chosen ILs. Analysis of time-resolved fluorescence studies, X-ray photoelectron spectroscopy, and infrared spectroscopy data has suggested that ILs help in removing excess lead from the surface of PNCs. Interestingly, it has also been observed that the chemical stability of PNCs can be increased considerably in the presence of ILs. More interestingly, the investigations have further shown that IL-treated PNCs are stable even at a single-particle level. The outcomes essentially show that ILs can effectively be used in obtaining chemically stable and photostable PNCs with improved photophysical properties.