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An attempt is made to study the effects of gamma irradiation on multi walled carbon nanotubes (MWCNTs) with a specific focus on surface modification, structural changes and identification of irradiation generated defects on their surface. The as-received MWCNTs were chemically treated in order to attach required functional group on the surface and to remove traces of metallic impurities. The MWCNTs were then gamma irradiated at 25, 50, 75 and 100 kGy doses. Micro Raman analysis was performed on irradiated MWCNTs to estimate the irradiation induced defects on their surface, which revealed that the number of defects increased with dose. XRD analysis was also performed to observe the same and it was revealed that the MWCNTs were subjected to micro-straining. The selective area electron diffraction pattern revealed that traces of amorphous carbon were formed after irradiation. Various defects such as bending, variation of internal and external diameter, wall damages formed on the MWCNTs was verified using TEM. It is concluded that subjecting MWCNTs to irradiation sources has produced structural changes and defects on their surface which can influence the properties of nanocomposites. [ABSTRACT FROM AUTHOR]

Nanocrystalline TiO2 sample was prepared by high-energy ball mill method. A known quantity of anatase phase-TiO2 was milled for 83 h in air. The samples were collected at intervals of 5 h of milling. The XRD patterns were recorded for all the samples. The crystal structure changed from anatase phase for bulk material to rutile-rich phase for nanocrystalline material. Nanocrystalline TiO2, which is a mixture of anatase, rutile, and srilankite phase, was prepared by milling for 60 h. The XRD pattern of unmilled anatase phase of TiO2 could be refined with I41/amd space group. The crystallite size of the TiO2 was found to decrease with milling time upto 50 h and then the size of rutile phase increases while the sizes of anatase and srilankite phases remain constant upto 60 h of milling. After 60 h, the sizes of all the phases remain constant. The average crystallite size for rutile phase is found to be 12 nm after 60 h of milling. [ABSTRACT FROM AUTHOR]

We study the efficiency of molecular hydrogen recombination on grain surfaces using both the rate equation (which tracks the average number of species) and the master equation (which tracks the expectation values of the species). We have incorporated Langmuir-Hinselwood rejection term in obtaining the efficiency. We vise this result to compute H2 production rates as a function of the grain temperature and accretion rate of atomic hydrogen. Our general conclusion is that the H2 formation efficiency is very much dependent on the grain temperature and the accretion rate of the atomic hydrogen on grains. We provide tables of H2 production rates which could be readily used for future calculation of production of more complex molecules in the gas phase. [ABSTRACT FROM AUTHOR]

Nanocrystalline TiO2 sample was prepared by high-energy ball mill method. A known quantity of anatase phase-TiO2 was milled for 83 h in air. The samples were collected at intervals of 5 h of milling. The XRD patterns were recorded for all the samples. The crystal structure changed from anatase phase for bulk material to rutile-rich phase for nanocrystalline material. Nanocrystalline TiO2, which is a mixture of anatase, rutile, and srilankite phase, was prepared by milling for 60 h. The XRD pattern of unmilled anatase phase of TiO2 could be refined with I41/amd space group. The crystallite size of the TiO2 was found to decrease with milling time upto 50 h and then the size of rutile phase increases while the sizes of anatase and srilankite phases remain constant upto 60 h of milling. After 60 h, the sizes of all the phases remain constant. The average crystallite size for rutile phase is found to be 12 nm after 60 h of milling. [ABSTRACT FROM AUTHOR]

The development of artificial light-harvesting systems mimicking the natural photosynthesis method is an ever-growing field of research. Numerous systems such as polymers, metal complexes, POFs, COFs, supramolecular frameworks etc. have been fabricated to accomplish more efficient energy transfer and storage. Among them, the supramolecular coordination complexes (SCCs) formed by non-covalent metal-ligand interaction, have shown the capacity to not only undergo single and multistep energy migration but also to utilize the harvested energy for a wide variety of applications such as photocatalysis, tunable emissive systems, encrypted anti-counterfeiting materials, white light emitters etc. This review sheds light on the light-harvesting behavior of both the 2D metallacycles and 3D metallacages where design ingenuity has been executed to afford energy harvesting by both donor ligands as well as metal acceptors., (© 2024 Wiley‐VCH GmbH.)

Type 2 diabetes mellitus (T2DM) predominantly considered a metabolic disease is now being considered an inflammatory disease as well due to the involvement of meta-inflammation. Obesity-induced adipose tissue inflammation (ATI) is one of the earliest phenomena in the case of meta-inflammation, leading to the advent of insulin resistance (IR) and T2DM. The key events of ATI are orchestrated by macrophages, which aggravate the inflammatory state in the tissue upon activation, ultimately leading to systemic chronic low-grade inflammation and Non-Alcoholic Steatohepatitis (NASH) through the involvement of proinflammatory cytokines. The CD44 receptor on macrophages is overexpressed in ATI, NASH, and IR. Therefore, we developed a CD44 targeted Hyaluronic Acid functionalized Graphene Oxide Quantum Dots (GOQD-HA) nanocomposite for tissue-specific delivery of metformin. Metformin-loaded GOQD-HA (GOQD-HA-Met) successfully downregulated the expression of proinflammatory cytokines and restored antioxidant status at lower doses than free metformin in both palmitic acid-induced RAW264.7 cells and diet induced obese mice. Our study revealed that the GOQD-HA nanocarrier enhanced the efficacy of Metformin primarily by acting as a therapeutic agent apart from being a drug delivery platform. The therapeutic properties of GOQD-HA stem from both HA and GOQD having anti-inflammatory and antioxidant properties respectively. This study unravels the function of GOQD-HA as a targeted drug delivery option for metformin in meta-inflammation where the nanocarrier itself acts as a therapeutic agent., (© 2023. The Author(s).)

Objective: To compare the growth and neurodevelopmental outcome of term, singleton babies conceived by assisted reproduction with those of naturally conceived babies., Methods: A cohort study evaluating the growth delay in terms of proportion of babies with wasting (W/L < -2SD) at 6, 12 and 24 mo follow-up. Developmental delay was defined as either motor or mental developmental quotient < 70 in DASII., Results: Amongst the 128 artificially conceived babies, at 6 and 12 mo, the proportions of babies with wasting (21.1% and 17.2%), motor (7.03%, 6.3%), and mental developmental delays (5.5% and 3.9%) were significantly higher (p < 0.05) compared to the naturally conceived babies (10.94%, 8.6%, 1.6%, 0.8%, 0.8% and 0%, respectively). However, at 24 mo, the difference in outcomes were not statistically significant (p > 0.05)., Conclusion: The growth and neurodevelopment of artificially conceived babies may be delayed in early infancy but they normalize to catch up with their naturally conceived peers by 24 mo., (© 2022. Dr. K C Chaudhuri Foundation.)

Developing artificial light-harvesting scaffolds with a cascade energy transfer process is significant for better understanding of photosynthesis. Here, we report [3+3] self-assembled Pt II fluorescent macrocycles (3 a and 3 b) as light-harvesting platforms with cascade energy transfer. The Pt II macrocycles aggregate into nanospheres and show emission-enhancement characteristics upon increasing water content in acetone medium. These aggregates (3a a and 3b a ) serve as energy donors when mixed with the hydrophobic dye Eosin-Y (ESY). In the presence of a second dye, Nile Red (NiR), an unusual sequential two-step energy transfer takes place from the macrocycles to NiR. In this case, ESY acts as a bridge in the relay mode. Additionally, a unique strategy to control such an energy transfer process by tuning the chain length of the alkyl group attached to the periphery of the macrocycles is demonstrated., (© 2022 Wiley-VCH GmbH.)

Objective: To study the social, demographic and clinical profile of functional constipation (FC) in children., Methods: A cross-sectional study was performed in a tertiary-care hospital to assess prevalence and profile of functional constipation among children (1-18 years) using Rome IV diagnostic criteria., Results: Children with FC constituted 5.56% (87/1565) of hospital attendees. 64.4% were between 2-6 years old and 48.3% had a past history of use of laxatives. Painful defecation was the commonest (62.1%) presenting symptom, while avoidance to school toilet was the commonest (25.3%) precipitating factor. Fecal impaction was present in 70.1% children., Conclusion: Functional constipation was the commonest cause of constipation, and a majority of these children had associated fecal impaction.

Light-harvesting is one of the key steps in photosynthesis, but developing artificial light-harvesting systems (LHSs) with high energy transfer efficiencies has been a challenging task. Here we report fluorescent hexagonal Pt(II) metallacycles as a new platform to fabricate artificial LHSs. The metallacycles ( 4 and 5 ) are easily accessible by coordination-driven self-assembly of a triphenylamine-based ditopic ligand 1 with di-platinum acceptors 2 and 3 , respectively. They possess good fluorescence properties both in solution and in the solid state. Notably, the metallacycles show aggregation-induced emission enhancement (AIEE) characteristics in a DMSO-H 2 O solvent system. In the presence of the fluorescent dye Eosin Y (ESY), the emission intensities of the metallacycles decrease but the emission intensity of ESY increases. The absorption spectrum of ESY and the emission spectra of the metallacycles show a considerable overlap, suggesting the possibility of energy transfer from the metallacycles to ESY, with an energy transfer efficiency as high as 65% in the 4 a +ESY system.

Considerable progress in platinum metallacycle-based supramolecular polymerization has promoted the fabrication and application of supramolecular materials. However, despite recent advances, supramolecular polymers constructed through platinum metallacycle-based host-guest complexation remain rare because of the dynamics of platinum metallacycles. Here, we achieve linear supramolecular polymerization via platinum metallacycle-based host-guest complexation by following the design rule of suppressing the dynamics of the metallacycles. The establishment of the platinum metallacycle-based host-guest system and the realization of this type of supramolecular polymerization are expected to open opportunities for platinum metallacycle-based functional materials.

Imine condensation has been known to chemists for more than a century and is used extensively to synthesize large organic cages of defined shapes and sizes. Surprisingly, in the context of the synthetic methods for organic imine cages (OICs), a self-sorting/self-selection (molecular marriage) process has been overlooked over the years. Such processes are omnipresent in nature, from the creation of galaxies to the formation of the smallest building blocks of life (the cell). Such processes have the incredible ability to guide a system toward the formation of a specific product or products out of a collection of equally probable multiple possibilities. This Minireview sheds light on new opportunities in cage design offered by the self-sorting/self-selection protocol in OICs. Recent efforts to explore organic cages for various exciting new applications are discussed; for example, for detection of harmful small organic molecules, as templates for nucleation of metal nanoparticles (MNPs), and as proton-conducting materials., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The recent progress in platinum(II) coordination-driven supramolecular polymers has had a substantial effect on the design of functional soft materials. However, the prospect of realizing polymerization induced by platinum(II) metallacycle-based host-guest interactions has received little attention until recently. Here we report the realization of supramolecular polymerization driven by platinum(II) metallacycle-based host-guest interactions both in the solid state and in solution. On the basis of the disclosed polymerization mechanism, we present a new strategy for the preparation of platinum(II) metallacycle-based supramolecular polymers.

Morphology of nanomaterials has a strong impact on their chemical/physical properties, and controlled synthesis of such materials with desirable morphology is a major challenge. This article presents the role of a building block in the morphology of organic cage particles. In this context, three organic cages (A 3 X 2 , B 3 X 2 , and C 3 X 2 ) were devised from triphenylamine-based dialdehydes (A-C) and a flexible triamine (X) by utilizing dynamic imine chemistry. All of the synthesized cages were characterized by various spectroscopic techniques, which suggested the formation of [3+2] assembled architectures. Though the cages are isostructural, structural variation in the aldehyde building blocks imparted by the incorporation of phenyl moieties into the triphenylamine core produces morphologically diverse cage particles, as indicated by SEM. The synthesized cages were found to be fluorescent; the reduced analogue of cage A 3 X 2 (A 3 X 2 r ) was tested to explore its use as a chemosensor for the detection of nitroaromatic explosives. The experimental findings suggest high selectivity and sensitivity of A 3 X 2 r towards picric acid (PA) among the various nitroaromatics tested. A theoretical investigation of fluorescence quenching suggested that formation of a ground-state charge-transfer complex with a resonance energy-transfer (RET) process could be the main reason behind such selectivity of the cage towards PA., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Two shape-persistent covalent cages (CC1(r) and CC2(r)) have been devised from triphenyl amine-based trialdehydes and cyclohexane diamine building blocks utilizing the dynamic imine chemistry followed by imine bond reduction. The cage compounds have been characterized by several spectroscopic techniques which suggest that CC1(r) and CC2(r) are [2+3] and [8+12] self-assembled architectures, respectively. These state-of-the-art molecules have a porous interior and stable aromatic backbone with multiple palladium binding sites to engineer the controlled synthesis and stabilization of ultrafine palladium nanoparticles (PdNPs). As-synthesized cage-embedded PdNPs have been characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and powder X-ray diffraction (PXRD). Inductively coupled plasma optical emission spectrometry reveals that Pd@CC1(r) and Pd@CC2(r) have 40 and 25 wt% palladium loading, respectively. On the basis of TEM analysis, it has been estimated that as small as ∼1.8 nm PdNPs could be stabilized inside the CC1(r), while larger CC2(r) could stabilize ∼3.7 nm NPs. In contrast, reduction of palladium salts in the absence of the cages form structure less agglomerates. The well-dispersed cage-embedded NPs exhibit efficient catalytic performance in the cyanation of aryl halides under heterogeneous, additive-free condition. Moreover, these materials have excellent stability and recyclability without any agglomeration of PdNPs after several cycles.

A new synthetic protocol based on one-pot, copper(I)-catalysed multicomponent reaction of formaldehyde, secondary amine and terminal alkyne has been employed to postsynthetically modify a self-assembled nanoscopic organic cage. By employing this synthetic strategy, three new cages appended with phenyl-, xylyl- and naphthyl-acetylene moieties have been synthesised. The resulting modified cages were characterised by using a range of spectroscopic techniques. The synthesised cages were fluorescent and thus one of them was tested to explore the potential use of such compounds as chemosensors for the detection of nitroaromatics. Experimental findings suggest a high selective quenching of initial fluorescence intensity in the presence of nitroaromatic compounds. Furthermore, it has been observed that among the various nitroaromatics tested, nitrophenolic compounds have better quenching ability., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The selective formation of a single isomer of a [3+2] self-assembled organic cage from a reaction mixture of an unsymmetrical aldehyde and a flexible amine is discussed. The experimental and theoretical findings suggest that in such a process, the geometric features of the aldehyde play a key role.

Dynamic covalent imine chemistry has been utilized to synthesize a fluorescent [3+2] self-assembled nanoscopic organic cage. The fluorescent nature of the reduced analogue of the cage was further exploited for the highly selective detection of the explosive picric acid (PA).

A supramolecular approach that uses hydrogen-bonding interaction as a driving force to accomplish exceptional self-sorting in the formation of imine-based covalent organic cages is discussed. Utilizing the dynamic covalent chemistry approach from three geometrically similar dialdehydes (A, B, and D) and the flexible triamine tris(2-aminoethyl)amine (X), three new [3+2] self-assembled nanoscopic organic cages have been synthesized and fully characterized by various techniques. When a complex mixture of the dialdehydes and triamine X was subjected to reaction, it was found that only dialdehyde B (which has OH groups for H-bonding) reacted to form the corresponding cage B3X2 selectively. Surprisingly, the same reaction in the absence of aldehyde B yielded a mixture of products. Theoretical and experimental investigations are in complete agreement that the presence of the hydroxyl moiety adjacent to the aldehyde functionality in B is responsible for the selective formation of cage B3X2 from a complex reaction mixture. This spectacular selection was further analyzed by transforming a nonpreferred (non-hydroxy) cage into a preferred (hydroxy) cage B3X2 by treating the former with aldehyde B. The role of the H-bond in partner selection in a mixture of two dialdehydes and two amines has also been established. Moreover, an example of unconventional imine bond metathesis in organic cage-to-cage transformation is reported., (Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Unprecedented self-sorting of three-dimensional purely organic cages driven by dynamic covalent bonds is described. Four different cages were first synthesized by condensation of two triamines and two dialdehydes separately. When a mixture of all the components was allowed to react, only two cages were formed, which suggests a high-fidelity self-recognition. The issue of the preference of one triamine for a particular dialdehyde was further probed by transforming a non-preferred combination to either of the two preferred combinations by reacting it with the appropriate triamine or dialdehyde.

We present laboratory data on pure, layered and mixed CO and O2 ices relevant for understanding the absence of gaseous O2 in space. Experiments have been performed on interstellar ice analogues under ultra high vacuum conditions by molecular deposition at 14 K on a gold surface. A combination of reflection absorption infrared spectroscopy (RAIRS) and temperature programmed desorption (TPD) is used to derive spectroscopic and thermodynamic properties of the ices. It is found that for pure ices the desorption energy of O2 is larger than that of CO and N2. TPD spectra reveal similar desorption processes for all examined CO-O2 ice morphologies. The different amorphous and crystalline components of pure 13CO RAIR spectra are analyzed. The RAIRS data of the 13CO stretching vibration show a significant difference between layered and mixed CO-O2 ices: layered CO-O2 ices resemble that of pure 13CO whereas the spectra of mixed ices are broadened. The experiments also show that the sticking probabilities of O2 on CO and O2 on O2 are close to unity. These new results are compared with recently analyzed data of CO-N2 ices. The differences in the TPD and RAIRS spectra of the CO-N2 and CO-O2 ice systems are explained by differences in quadrupole intermolecular interactions and by different crystallization processes of these ices.