Comprehensive characterization of the structure of Zr-based metallic glasses.

Structure of metallic glasses fascinates as the generic amorphous structural template for ubiquitous systems. Its specification necessitates determination of the complete hierarchical structure, starting from short-range-order (SRO) → medium-range-order (MRO) → bulk structure and free volume (FV) distribution. This link has largely remained elusive since previous investigations adopted one-technique-at-a-time approach, focusing on limited aspects of any one domain. Reconstruction of structure from experimental data inversion is non-unique for many of these techniques. As a result, complete and precise structural understanding of glass has not emerged yet. In this work, we demonstrate the first experimental pathway for reconstruction of the integrated structure, for Zr 67 Ni 33 and Zr 52 Ti 6 Al 10 Cu 18 Ni 14 glasses. Our strategy engages diverse (× 7) multi-scale techniques [XAFS, 3D-APT, ABED/NBED, FEM, XRD, PAS, FHREM] on the same glass. This strategy complemented mutual limitations of techniques and corroborated common parameters to generate complete, self-consistent and precise parameters. Further, MRO domain size and inter-void separation were correlated to identify the presence of FV at MRO boundaries. This enabled the first experimental reconstruction of hierarchical subset: SRO → MRO → FV → bulk structure. The first ever image of intermediate region between MRO domains emerged from this link. We clarify that determination of all subsets is not our objective; the essence and novelty of this work lies in directing the pathway towards finite solution, in the most logical and unambiguous way.

Chemical composition, pesticidal activities and in-silico investigation of Hedychium spicatum Sm. chloroform extract.

The present study aimed to identify the bioactive constituents in the chloroform extract of H. spicatum rhizomes (HS-RCLE), further evaluated for its in-vitro pesticidal activities validating via molecular docking techniques. GC/MS analysis of HS-RCLE identified 14 compounds contributing 84.1 % of the total composition. The extract was dominated by oxygenated sesquiterpenes (43.1 %) with curcumenone (25.2 %) and coronarin E (14.8 %) as the major compounds. The extract recorded 89.4 % egg hatchability inhibition and 82.6 % immobility of Meloidogyne incognita, 66.7 % insecticidal activity on Spodoptera litura, 100 % phytotoxic activity on Raphanus raphanistrum seeds, and 74.7 % anti-fungal activity on Curvularia lunata at the respective highest dose studied. The biological activities were furthermore validated by using docking studies on certain proteins/enzymes namely acetylcholinesterase (PBD ID: IC2O), carboxylesterase (PDB ID: 1CI8), acetohydroxyacid synthase (PBD ID: 1YHZ) and trihydroxy naphthalene reductase (PBD ID: 3HNR). The bioactivity of the major constituents of the extract was predicted with the help of in silico PASS studies. HS-RCLE was observed to be a viable alternative source of natural pesticidal agents and paves the way for further studies on its mechanistic approaches and field trials to ascertain its pesticidal studies.

Polyether phases of formic acid revealed under high pressure.

Evolutionary structure searches reveal that at 20 GPa, formic acid (FA) transforms to an orthorhombic ether-chain polymer phase, ruling out hydrogen bond symmetrization, followed by a novel crowned cyclic-ether tetragonal phase above 60 GPa. Emergence of characteristic polyether and new OH stretching modes in infrared experiments validate the findings. Resemblance of polymer chain with a cosmopolymer polyoxymethylene, shows an engrossing multifaceted evolution of FA.

Dietary lutein supplementation improves immunity and antioxidant status of captive Indian leopards (Panthera fusca).

Indian leopards kept in zoos are fed solely on carabeef on bone (CBB) diets. Carabeef contains lesser or no carotenoids. Hence, the captive Indian leopard diets are suspected to be deficient in carotenoids while their wild counterparts acquire these pigments from their natural prey. Lutein is a vital carotenoid that plays its role as an antioxidant and immunomodulator. This experiment investigates the effect of lutein supplementation on antioxidant status, immunity, and stress in captive Panthera fusca fed CBB diets. Nine leopards were used based on 3 × 3 replicated Latin square designs in the experiment. Groups CON, LUT20, and LUT40 were supplemented with 0, 20, and 40 ppm of lutein, respectively. Each experiment comprised of 10 days of wash-out period, 11 days of adaptation, and 4 days of collection. Digestibility of crude protein (CP) was higher (p < .01) in groups LUT20 and LUT40. Serum concentration of protein, globulin, urea (p < .05), total carotenoids, total antioxidant capacity (TAC), catalase (CAT) activity, and lymphocyte transformation test (LTT) index were higher (p < .001) in groups LUT20 and LUT40. Activity of superoxide dismutase (SOD) and serum concentration of immunoglobulin were higher (p < .001) in group LUT20. Serum concentration of malonaldehyde (MDA) and fecal concentration of cortisol decreased (p < .001) in groups LUT20 and LUT40. Serum concentration of total immunoglobulin (µg/ml) and LTT were higher in group LUT20. Fecal concentration of cortisol (ng/g) was lower in LUT20 and LUT40. The study concludes that supplementation of lutein at 20 ppm would improve antioxidant status and immunity and alleviate stress in captive Indian leopards.

First principles investigations on the controversy of structural phase transitions in thorium dialuminide under pressure.

We study the high pressure structural aspects of thorium dialuminide, ThAl2, by performing evolutionary crystal structure searches and first principles calculations. We predict a phase transition from the ambient AlB2-type hexagonal structure to a P63/mmc hexagonal structure above 2.4 GPa. We also note that the new structure remains stable up to 50 GPa. This differs from the finding of an earlier study in which three phase transitions were reported close to 5.5, 12 and 25 GPa. An analysis of the electronic structures, Bader charge and electron localization function (ELF) indicates a complex chemical bonding comprising partial metallic, ionic (Th-Al) and covalent (Al-Al) characters in the ambient phase. Comparison of crystal parameters and ELFs for ambient and high pressure phases indicates that a change of Al-Al bonding under pressure is responsible for the structural phase transition. Furthermore, we computed the high P-T phase diagram by including the temperature effects via free energies for the most relevant structures, namely, AlB2-type, MgCu2-type and new hexagonal. We found that a MgCu2-type structure becomes stable only under high P-T conditions. We also provide a plausible explanation for the observed isostructural transition in the ambient AlB2-type structure at 5.5 GPa.

Effect of Arsenic Stress on Expression Pattern of a Rice Specific miR156j at Various Developmental Stages and Their Allied Co-expression Target Networks.

In plants, arsenic (As) stress modulates metabolic cascades at various developmental stages by influencing the pattern of gene expressions mediated by small non-coding RNAs, especially Micro-RNAs, involved in the moderation of a myriad of cellular processes needed for plant adaptation upon oxidative stress. miR156j of miR156 gene family, involved mainly in the regulation of growth and development in plants. This study was designed to find out the role of arsenic toxicity on Osa-miR156j expression in all physiological growth stages. To better understand the functional role of Osa-miR156j in rice, we observed the expression in different developmental stages (seedlings, tillering and flowering) and various tissues of leaf, stem and root tissues (at 0, 24, 48, and 72 h) under 25 µM arsenite [As (III)] exposure. Additionally, using bioinformatic tools to target genes of Osa-miR156j and the potential co-expressed genes were explored at different development stages in the various tissues of rice under stress conditions. The expression of Osa-miR156j showed its temporal downregulation in various tissues in different developmental stages. Of note, the downregulation was more pronounced in root tissues at seedlings, tillering, and flowering stages during 0-72 h under arsenite exposure as compared to other tissues. Overall, the As stress altered the gene expression more prominently at seedlings developmental stage followed by flowering and tillering. Additionally, through the In silico approach, the target functions and presence of oxidative stress-responsive cis-acting regulatory elements/motifs also confirmed Osa-miR156j involvement in the regulation of arsenic stress in rice. The findings of this study demonstrate the prominent role of Osa-miR156j in rice under arsenite stress, which was found to modulate the metabolic activities in rice plants at different developmental stages, and thus it might be useful for the development of arsenic tolerant varieties.

Competing Interactions: Evolution of Inter and Intramolecular Hydrogen Bonds in Salicylic Acid at High Pressures.

Benzoic acid derivatives are important molecular systems in the pharmaceutical industry. Salicylic acid is distinct among the derivatives of benzoic acid due to the presence of an intramolecular hydrogen bond. With a view to study the evolution of inter and intramolecular hydrogen bonding at shorter length scales, in situ high pressure Raman spectroscopic measurements, angle dispersive X-ray diffraction experiments, and density functional theory (DFT) based first principle calculations have been carried out on crystalline salicylic acid. Subtle structural modifications are noted across ∼1 GPa leading to structural phase transition to a new crystalline phase above 7 GPa which is reversible. Substantial softening of the OH stretching Raman mode associated with intramolecular hydrogen bond is observed prior to the transition pressure. Possible molecular configurations associated with tautomerization are discussed with the aid of DFT calculations.

Surgical Management of Primary Hyperparathyroidism in the Era of Focused Parathyroidectomy: A Study in Tertiary Referral Centre of North India.

BACKGROUND: Despite the benefits of focused parathyroidectomy (FPTx), few studies have questioned its durability with lower long-term cure rates than bilateral or conventional parathyroidectomy (CPTx). The objective of this study is to bring out the information on the type of surgical management versus cure rate, recurrence, and role of intra-operative parathyroid hormone (IOPTH) level monitoring of PHPT patients. MATERIAL AND METHODS: This was a retrospective study of all PHPT patients treated at our center based on operative approach (CPTx vs FPTx) or use of IOPTH. Treatment failure was divided into persistent or recurrent disease, based on documentation of hypercalcemia in combination with an inappropriate PTH within 6 months or more of surgery, respectively. RESULTS: Overall, 50.78% patients underwent CPTx and 49.32% FPTx. 29 FPTx were converted to CPTx. Intention to treat analysis between CPTx and FPTx showed that the persistence rate was not statistically different at 2.54% and 4%, respectively (P = 0.98). Furthermore, when the persistence rate was scrutinized by a treatment received (TR) instead of ITT analysis, the persistence rate was higher for the patients who underwent TR-CPTX than for the patients subjected to TR-FPTX (3.22% vs 1.08%) but not significant statistically. We further analyzed the outcome of FPTx with IOPTH (n = 213) and FPTx without IOPTH (n = 28). The outcome did not differ between two groups statistically. CONCLUSION: FPTx yields a similar success rate as compared to CPTx even in symptomatic PHPT patients and can be performed safely even without intra-opeartive adjunct IOPTH in selected patients.

Pressure induced multi-centre bonding and metal-insulator transition in PtAl2.

A study on pressure induced metallization or metal-insulator transition (MIT) of materials is of enormous importance in high pressure research not only in view of various possible device applications but also for basic physical insight into their mechanism. Though the former transition (metallization) is quite common, the latter one (MIT) is comparatively rare, and only a few simple metals (Na, Al, etc.) are predicted to be an insulator at megabar pressure. In this work, we have shown that the binary intermetallic compound (PtAl2) exhibits a pressure induced metal-insulator transition comparatively at low pressure, near ∼28 GPa. By means of first principles calculations, we have established that a unique multi-centre bonding is developed under pressure which causes charge-density-ordering in the system and finally leads to MIT and structural phase transition involving unit cell reduction. In search of some exotic properties, we have found that the system has a good thermoelectric figure-of-merit in its insulating phase.

Partial replacement of dietary buffalo meat on the bone with chicken carcass improves serum antioxidant profile of zoo-housed Indian leopards (Panthera pardus fusca).

This experiment was conducted to study the effect of gradual replacement of dietary buffalo meat on the bone (BMB) with chicken carcass (CC) on nutrient utilization, serum cortisol, and total serum antioxidant profile of zoo-housed Indian leopard. Twelve adult leopards were randomly distributed into a replicated Latin square design comprising three treatments, three periods, four animals, and three sequences. Leopards in group T1 were fed normal zoo diet of BMB. On the basis of dry matter, 10% and 20% of BMB was replaced with CC in groups T2 and T3 , respectively. Each experimental period comprised 21 days. During each period, a digestion trial of 4-day collection period was conducted after an adaptation period of 17 days. On Day 21 of each experimental period, blood was collected from all the animals by puncturing the ventral coccygial vein. Intake and apparent digestibility of major nutrients were similar among the groups. Replacement of 20% BMB with addition of CC increased (p < 0.001) the calculated supply of I, niacin, and vitamin A. Carotenoid intake increased (p < 0.01) with increased level of CC in the diet. Serum concentration of cortisol decreased (p < 0.01) whereas serum concentration of total carotenoids increased (p < 0.001) with increased level of CC in the diet. Serum concentration of antioxidant enzymes increased (p < 0.001) with increased level of CC in the diet. It was concluded that replacement of 20% of BMB with CC increased antioxidant profile. This may reduce oxidative stress in zoo-housed Indian leopards without any adverse effect on nutrient utilization.

A unique metallic phase of H3S at high-pressure: sulfur in three different local environments.

We propose a new metallic phase (R3[combining macron]m, Z = 24) for H3S in a large pressure interval (∼108-166 GPa) using an evolutionary crystal structure search algorithm combined with first-principles calculations. This structure consists of SH6, SH3 and S units which are connected through strong SH hydrogen-bonds. It supports four-types of SH hydrogen-bonds that symmetrize at ∼166 GPa. This is the only phase in the H-S family where sulfur exists in three different local environments. Sulfur in SH6 behaves as a cation, like in the SF6 molecule, whereas other sulfurs behave as anions. Hydrogens in SH6 behave like halogens (anions) whereas other hydrogens behave like alkalis (cations). The new structure has a substantially smaller DOS at the Fermi-level in comparison to earlier structures R3m and Im3[combining macron]m. This implies a lower superconducting temperature (TC) for the new phase and thus questions the validity of earlier high-TC explanations. We also find that S-H covalent bonds are different from the B-B bonds of MgB2.

Clinico-Pathological Profile of Anaplastic Thyroid Carcinoma in an Endemic Goiter Area.

INTRODUCTION: Anaplastic thyroid cancers (ATCs) usually present in the sixth to seventh decades of life and little is known about the disease in young patients. The aim was to analyze the clinicopathological characteristics diagnosed with ATC in an iodine-deficient area. MATERIAL AND METHODS: The medical records of 100 patients diagnosed with ATC at a tertiary care hospital between 1991 and 2013 were reviewed. RESULTS: The mean age of patient was 58 years. About 34 patients were ≤50 years. The common presentation was that of a rapidly growing fixed and hard mass (64%). Due to rapid expansion, 27% patients experienced severe pain. About one-third presented as sudden enlargement of pre-existing goiter over few weeks. The median duration of symptoms before diagnosis was 3 months. About 41% presented with lymph node enlargement and 31% with distant metastasis. The diagnosis was established with fine-needle aspiration or core biopsy. Histopathology was available in 32 patients and showed four major patterns: spindle cell (9), giant cell (7), epithelioid (5), squamoid (1), mixed type in 10 patients. Eight patients presenting with stridor required emergency tracheostomy for airway control. Total thyroidectomy with or without lymph node dissection was possible in 21 patients. Patients received radiotherapy with or without chemotherapy. Median overall survival was 3 months. Overall survival was significantly better in patients receiving some form of treatment. CONCLUSION: ATC in endemic goiter areas presents at an earlier age. One-third of ATC is due to anaplastic transformation of pre-existing goiter and majority of the patients refuse treatment due to dismal outcome.

Structural Phase Transitions in PtIn2 at High Pressure: A Theoretical Investigation.

A study of the bonding and electronic properties of intermetallics under pressure is crucial in the design and development of novel materials for useful applications. These properties are largely controlled by the underlying crystal structures. Here we investigated the high-pressure structural behavior of PtIn2 using crystal structure search calculations, which efficiently combine evolutionary algorithms and state-of-the-art density functional theory. Three new crystal structures, namely, Fe2B-type (I4/mcm, Z = 2), cotunnite-type (Pnma, Z = 4), and monoclinic (C2/m, Z = 2), are proposed at about 9.4, 13.5, and 47.5 GPa, respectively. With pressure, the covalent character of the Pt-In pair interaction is found to increase because of enhancement of spd hybridization, and structural transitions are rationalized in terms of the covalency increase.

The synthesis of unconventional stoichiometric compounds in the K-Br system at high pressures.

Recently, the search for and synthesis of unconventional stoichiometric compounds have become one of the most active areas of high pressure research. Here, we report the synthesis of two new stoichiometric compounds, namely KBr3 and KBr5, at high pressures in the K-Br system. Until now, KBr was the only known compound in this system. Two independent experimental techniques, namely Raman spectroscopy and X-ray diffraction measurements, were employed to detect and confirm the formation of the new compounds. A room temperature chemical reaction between KBr and Br2 resulted in the formation of orthorhombic KBr3 at ∼2.0 GPa. Further compression led to the formation of monoclinic KBr5 at ∼6.0 GPa. This was accompanied by an anomalously large pressure (>2 GPa) increase inside the sample chamber and it remained stable up to the highest pressure, 24 GPa, of our study. Upon decompression, KBr5 remained stable down to 5.0 GPa. High-pressure (14-20 GPa) and high-temperature (>1500 K) laser heating experiments showed the decomposition of KBr5 into KBr3 (trigonal) and Br2 with a large volume reduction. First-principles structural searches were carried out to solve the composition and related crystal structures. The proposed structures give good description of the experimental Raman spectra and X-ray diffraction data. The electronic structure calculations reveal semiconducting behaviour for these compounds.

Prediction of a novel 10-fold gold coordinated structure in AuIn2 above 10 GPa.

A 10-fold gold coordinated tetragonal structure is predicted for AuIn2 above 10 GPa by employing the first-principles crystal structure search method. This structure remains the lowest enthalpy structure up to the highest pressure of this study. Detailed electronic structure analysis is carried out to figure out the underlying factors responsible for the transition. Pressure induced electronic topological transition is found to be one of the main factors behind this transition. Phonon calculations show the softening of TA mode phonons and destruction of the giant Kohn anomaly in close proximity to the transition. Bader charge analysis shows the charge transfer increase from the In to Au atom under pressure. So this study has solved a long-standing structural puzzle of the AuIn2 above 10 GPa. This study is also expected to play an important role in our understanding of the pressure induced metallization of geophysically relevant oxides such as SiO2 and TiO2.

Role of 5f electrons in the structural stability of light actinide (Th-U) mononitrides under pressure.

Pressure induced structural sequences and their mechanism for light actinide (Th-U) mononitrides were studied as a function of 5f-electron number using first-principles total energy and electronic structure calculations. Zero pressure lattice constants, bulk module and C11 elastic module vary systematically with 5f-electron number implying its direct role on crystal binding. There is a critical 5f-electron number below which the system makes B1-B2 and above it B1-R3̄m-B2 structural sequence under pressure. Also, the B1-B2 transition pressure increases with increasing 5f-electron number whereas an opposite trend is obtained for the B1-R3̄m transition pressure. The ascending of N p anti-bonding states through the Fermi level at high pressure is responsible for the structural instability of the system. Above the critical 5f-electron number in the system a narrow 5f-band occurs very close to the Fermi level which allows the system to lower its symmetry via band Jahn-Teller type lattice distortion and the system undergoes a B1-R3̄m phase transition. However, below the critical 5f-electron number this mechanism is not favorable due to a lack of sufficient 5f-state occupancy and thus the system undergoes a B1-B2 phase transition like other ionic solids.

Proton transfer aiding phase transitions in oxalic acid dihydrate under pressure.

Oxalic acid dihydrate, an important molecular solid in crystal chemistry, ecology and physiology, has been studied for nearly 100 years now. The most debated issues regarding its proton dynamics have arisen due to an unusually short hydrogen bond between the acid and water molecules. Using combined in situ spectroscopic studies and first-principles simulations at high pressures, we show that the structural modification associated with this hydrogen bond is much more significant than ever assumed. Initially, under pressure, proton migration takes place along this strong hydrogen bond at a very low pressure of 2 GPa. This results in the protonation of water with systematic formation of dianionic oxalate and hydronium ion motifs, thus reversing the hydrogen bond hierarchy in the high pressure phase II. The resulting hydrogen bond between a hydronium ion and a carboxylic group shows remarkable strengthening under pressure, even in the pure ionic phase III. The loss of cooperativity of hydrogen bonds leads to another phase transition at ∼ 9 GPa through reorientation of other hydrogen bonds. The high pressure phase IV is stabilized by a strong hydrogen bond between the dominant CO2 and H2O groups of oxalate and hydronium ions, respectively. These findings suggest that oxalate systems may provide useful insights into proton transfer reactions and assembly of simple molecules under extreme conditions.

Hydrogen Bond Symmetrization in Glycinium Oxalate under Pressure.

The study of hydrogen bonds near symmetrization limit at high pressures is of importance to understand proton dynamics in complex bio-geological processes. We report here the evidence of hydrogen bond symmetrization in the simplest amino acid-carboxylic acid complex, glycinium oxalate, at moderate pressures of 8 GPa using in-situ infrared and Raman spectroscopic investigations combined with first-principles simulations. The dynamic proton sharing between semioxalate units results in covalent-like infinite oxalate chains. At pressures above 12 GPa, the glycine units systematically reorient with pressure to form hydrogen-bonded supramolecular assemblies held together by these chains.

Hydrogen bonds and ionic forms versus polymerization of imidazole at high pressures.

Imidazole (C3H4N2) is an important biomaterial for material research and applications. Our high-pressure Raman spectroscopic investigations combined with ab initio calculations on crystalline imidazole suggest that C-H---X (X = N, π) and N-H---N intermolecular hydrogen bonding interactions largely influence the nature of its structural and polymeric transformations under pressure. At pressures around ∼10 GPa, the reduction in the N---N distances close to the symmetrization limit and the emergence of the spectral features of the cationic form indicate the onset of proton disorder. The pressure-induced strengthening of the "blue-shifting hydrogen bonds" C-H---X (X = N, π) in this compound is revealed by the Raman spectra and the ab initio calculations. No polymer phase was retrieved on release from the highest pressure of 20 GPa in this study.

Investigation of short-range structural order in Zr69.5Cu12Ni11Al7.5 and Zr41.5Ti41.5Ni17 glasses, using X-ray absorption spectroscopy and ab initio molecular dynamics simulations.

Short-range order has been investigated in Zr69.5Cu12Ni11Al7.5 and Zr41.5Ti41.5Ni17 metallic glasses using X-ray absorption spectroscopy and ab initio molecular dynamics simulations. While both of these alloys are good glass formers, there is a difference in their glass-forming abilities (Zr41.5Ti41.5Ni17 > Zr69.5Cu12Ni11Al7.5). This difference is explained by inciting the relative importance of strong chemical order, icosahedral content, cluster symmetry and configuration diversity.