The Ising triangular-lattice antiferromagnet neodymium heptatantalate as a quantum spin liquid candidate.

Disordered magnetic states known as spin liquids are of paramount importance in both fundamental and applied science. A classical state of this kind was predicted for the Ising antiferromagnetic triangular model, while additional non-commuting exchange terms were proposed to induce its quantum version-a quantum spin liquid. However, these predictions have not yet been confirmed experimentally. Here, we report evidence for such a state in the triangular-lattice antiferromagnet NdTa7O19. We determine its magnetic ground state, which is characterized by effective spin-1/2 degrees of freedom with Ising-like nearest-neighbour correlations and gives rise to spin excitations persisting down to the lowest accessible temperature of 40 mK. Our study demonstrates the key role of strong spin-orbit coupling in stabilizing spin liquids that result from magnetic anisotropy and highlights the large family of rare-earth (RE) heptatantalates RETa7O19 as a framework for realization of these states, which represent a promising platform for quantum applications.

Gapless Quantum Spin Liquid in the Triangular System Sr_{3}CuSb_{2}O_{9}.

We report gapless quantum spin liquid behavior in the layered triangular Sr_{3}CuSb_{2}O_{9} system. X-ray diffraction shows superlattice reflections associated with atomic site ordering into triangular Cu planes well separated by Sb planes. Muon spin relaxation measurements show that the S=1/2 moments at the magnetically active Cu sites remain dynamic down to 65 mK in spite of a large antiferromagnetic exchange scale evidenced by a large Curie-Weiss temperature θ_{CW}≃-143 K as extracted from the bulk susceptibility. Specific heat measurements also show no sign of long-range order down to 0.35 K. The magnetic specific heat (C_{m}) below 5 K reveals a C_{m}=γT+αT^{2} behavior. The significant T^{2} contribution to the magnetic specific heat invites a phenomenology in terms of the so-called Dirac spinon excitations with a linear dispersion. From the low-T specific heat data, we estimate the dominant exchange scale to be ∼36 K using a Dirac spin liquid ansatz which is not far from the values inferred from microscopic density functional theory calculations (∼45 K) as well as high-temperature susceptibility analysis (∼70 K). The linear specific heat coefficient is about 18 mJ/mol K^{2} which is somewhat larger than for typical Fermi liquids.

Risk factors for bovine anthrax in Bangladesh, 2010-2014: a case-control study.

A matched case-control study was conducted in Bangladesh by enrolling case smallholdings of cattle affected with anthrax in the period of October 2010 to December 2014. The cases were initially reported by mass media and/or in surveillance reports from authorities concerned in the country. In total, 43 case smallholdings were enrolled. For each case, a control was matched by similarity in herd-size and rearing of animals, selected from a distantly located (within 3-10 km) place but within the same sub-district of the case farm. Data collected by administering a prototype questionnaire were analysed by matched-pair analysis and multivariable conditional logistic regression. Out of the 43 smallholdings, 41 were located in three adjoining districts: Pabna, Sirajganj and Tangail, apparently forming a spatial cluster, could be termed 'anthrax hot spot' in Bangladesh. Sick animal on farm or a nearby farm slaughtered in the recent past (odds ratio (OR) 12.2, 95% confidence interval (CI) 1.6-93.4, P = 0.016)), history of heavy rains occurring in the last 2 weeks preceding an outbreak (OR 13.1, 95% CI 1.2-147.1, P = 0.037) and disposing of dead animal into nearby water body (OR 11.9, 95% CI 1.0-145.3, P = 0.052) were independent risk factors for anthrax in cattle in the country.

Breakdown of Magnetic Order in the Pressurized Kitaev Iridate ß-Li_{2}IrO_{3}.

Temperature-pressure phase diagram of the Kitaev hyperhoneycomb iridate ß-Li_{2}IrO_{3} is explored using magnetization, thermal expansion, magnetostriction, and muon spin rotation measurements, as well as single-crystal x-ray diffraction under pressure and ab initio calculations. The Néel temperature of ß-Li_{2}IrO_{3} increases with the slope of 0.9 K/GPa upon initial compression, but the reduction in the polarization field H_{c} reflects a growing instability of the incommensurate order. At 1.4 GPa, the ordered state breaks down upon a first-order transition, giving way to a new ground state marked by the coexistence of dynamically correlated and frozen spins. This partial freezing in the absence of any conspicuous structural defects may indicate the classical nature of the resulting pressure-induced spin liquid, an observation paralleled to the increase in the nearest-neighbor off-diagonal exchange Γ under pressure.

Designer interface peptide grafts target estrogen receptor alpha dimerization.

The nuclear transcription factor estrogen receptor alpha (ERα), triggered by its cognate ligand estrogen, regulates a variety of cellular signaling events. ERα is expressed in 70% of breast cancers and is a widely validated target for anti-breast cancer drug discovery. Administration of anti-estrogen to block estrogen receptor activation is still a viable anti-breast cancer treatment option but anti-estrogen resistance has been a significant bottle-neck. Dimerization of estrogen receptor is required for ER activation. Blocking ERα dimerization is therefore a complementary and alternative strategy to combat anti-estrogen resistance. Dimer interface peptide "I-box" derived from ER residues 503-518 specifically blocks ER dimerization. Recently using a comprehensive molecular simulation we studied the interaction dynamics of ERα LBDs in a homo-dimer. Based on this study, we identified three interface recognition peptide motifs LDKITDT (ERα residues 479-485), LQQQHQRLAQ (residues 497-506), and LSHIRHMSNK (residues 511-520) and reported the suitability of using LQQQHQRLAQ (ER 497-506) as a template to design inhibitors of ERα dimerization. Stability and self-aggregation of peptide based therapeutics poses a significant bottle-neck to proceed further. In this study utilizing peptide grafted to preserve their pharmacophoric recognition motif and assessed their stability and potential to block ERα mediated activity in silico and in vitro. The Grafted peptides blocked ERα mediated cell proliferation and viability of breast cancer cells but did not alter their apoptotic fate. We believe the structural clues identified in this study can be used to identify novel peptidometics and small molecules that specifically target ER dimer interface generating a new breed of anti-cancer agents.

Origin of the Spin-Orbital Liquid State in a Nearly J=0 Iridate Ba_{3}ZnIr_{2}O_{9}.

We show using detailed magnetic and thermodynamic studies and theoretical calculations that the ground state of Ba_{3}ZnIr_{2}O_{9} is a realization of a novel spin-orbital liquid state. Our results reveal that Ba_{3}ZnIr_{2}O_{9} with Ir^{5+} (5d^{4}) ions and strong spin-orbit coupling (SOC) arrives very close to the elusive J=0 state but each Ir ion still possesses a weak moment. Ab initio density functional calculations indicate that this moment is developed due to superexchange, mediated by a strong intradimer hopping mechanism. While the Ir spins within the structural Ir_{2}O_{9} dimer are expected to form a spin-orbit singlet state (SOS) with no resultant moment, substantial frustration arising from interdimer exchange interactions induce quantum fluctuations in these possible SOS states favoring a spin-orbital liquid phase down to at least 100 mK.

Prevalence of sorbitol non-fermenting Shiga toxin-producing Escherichia coli in Black Bengal goats on smallholdings.

A cross-sectional survey was carried out in Bangladesh with the sampling of 514 Black Bengal goats on smallholdings to determine the presence of sorbitol non-fermenting (SNF) Shiga toxin-producing E. coli (STEC). Swab samples collected from the recto-anal junction were plated onto cefixime and potassium tellurite added sorbitol MacConkey (CT-SMAC) agar, a selective medium for STEC O157 serogroup, where this serogroup and other SNF STEC produce colourless colonies. The SNF E. coli (SNF EC) isolates obtained from the survey were investigated by PCR for the presence of Shiga toxin-producing genes, stx1 and stx2, and two other virulence genes, eae and hlyA that code for adherence factor (intimin protein) and pore-forming cytolysin, respectively. The SNF EC isolates were also assessed for the presence of the rfbO157 gene to verify their identity to O157 serogroup. The results revealed that the proportions of goats carrying SNF EC isolates and stx1 and stx2 genes were 6·2% (32/514) [95% confidence interval (CI) 4·4-8·7)], 1·2% (95% CI 0·5-2·6) and 1·2% (95% CI 0·5-2·6), respectively. All the SNF STEC tested negative for rfbO157, hlyA and eae genes. The risk for transmission of STEC from Black Bengal goats to humans is low.

Sorbitol non-fermenting shiga toxin-producing Escherichia coli in cattle on smallholdings.

We investigated faecal samples collected from the rectum of 518 cattle on 371 randomly selected smallholdings in Bangladesh for the presence of sorbitol non-fermenting (SN-F) shiga toxin-producing Escherichia coli (STEC). The SN-F isolates were tested for the presence of rfb O157, stx1, stx2, eae and hlyA genes by polymerase chain reaction (PCR). Seven SN-F isolates lacking these genes were profiled by pulsed-field gel electrophoresis (PFGE) to verify their clonality. SN-F E. coli was identified in 44 [8·5%, 95% confidence interval (CI) 6·4-11·2] samples; of these, 28 (5·4%, 95% CI 3·8-7·7) had shiga toxin-producing strains, although only two carried the rfb O157 gene. Thirteen isolates carried the hlyA gene while 18 harboured the eae gene. Based on PFGE, six pulsotypes were observed among the seven isolates that had no virulence genes. To the best of our knowledge this is the first report on shiga toxin-producing E. coli from direct rectal faecal samples of cattle on smallholdings.

Isosorbide Mononitrate versus Misoprostol for Cervical Ripening and Induction of Labour at Term.

To assess the efficacy and safety of isosorbide mononitrate (IMN) compared with misoprostol for cervical ripening and labour induction at term. In this comparative study two hundred term pregnant women with indication for induction of labour were randomly divided to receive either 40 mg IMN tablet vaginally (n=100) or 50 µg misoprostol tablet vaginally (n=100) every 6 hours interval for a maximum of 4 doses. Progress & outcome of cervical ripening, labour induction and adverse effects were assessed. Change in cervical score was higher in misoprostol group than IMN group. Time from start of medication to vaginal delivery in IMN group was significantly longer, 28.66 ± 5.283 hours, than in misoprostol group, 16.12 ± 5.581 hours. Vaginal delivery occurred in 77% in IMN group and 69% in misoprostol group. There were no tachysystole or uterine hyper stimulation in the IMN group while in misoprostol group it was 17% and 11% respectively. Maternal satisfaction was higher in IMN group. Cervical ripening is satisfactory with IMN. Though misoprostol is singly more effective than IMN but IMN with oxytocin results in more vaginal delivery. Fetal and maternal side effects are less in IMN group.

Two-dimensional superfluid density in an alkali metal-organic solvent intercalated iron selenide superconductor Li(C5H5N)0.2Fe2Se2.

We report the low-temperature electronic and magnetic properties of the alkali metal-organic solvent intercalated iron selenide superconductor Li(C5H5N)0.2Fe2Se2 using muon-spin-spectroscopy measurements. The zero-field muon spin relaxation (µSR) results indicate that nearly half of the sample is magnetically ordered and spatially phase separated from the superconducting region. The transverse-field µSR results reveal that the superfluid density of Li(C5H5N)0.2Fe2Se2 is two dimensional in nature. The temperature dependence of the penetration depth λ(T) can be explained using a two-gap s-wave model. This implies that, despite the 2D nature of the superfluid density, the symmetry of the superconducting gap remains unaltered to the parent compound FeSe.

First-order reorientation transition of the flux-line lattice in CaAlSi.

The flux-line lattice in CaAlSi has been studied by small-angle neutron scattering. A well-defined hexagonal flux-line lattice is seen just above H(c1) in an applied field of only 54 Oe. A 30° reorientation of this vortex lattice has been observed in a very low field of 200 Oe. This reorientation transition appears to be first-order and could be explained by nonlocal effects. The magnetic field dependence of the form factor is well-described by a single penetration depth of λ=1496(1) Å and a single coherence length of ξ=307(1) Å at 2 K. At 1.5 K, the penetration depth anisotropy is γ(λ)=2.7(1), with the field applied perpendicular to the c axis, and agrees with the coherence length anisotropy determined from critical field measurements.

Risk factors associated with anthrax in cattle on smallholdings.

SUMMARY Unprecedented high rates of anthrax outbreaks have been observed recently in cattle and humans in Bangladesh, with 607 human cases in 2010. By enrolling 15 case and 15 control cattle smallholdings in the spatial zone in July-September 2010, we conducted a case-control study, data of which were analysed by matched-pair analysis and multivariable conditional logistic regression. Feeding animals with uprooted and unwashed grass [odds ratio (OR) 41·2, 95% confidence interval (CI) 3·7-458·8, P=0·003], and feeding water hyacinth (Eichhornia crassipes) (OR 22·2, 95% CI 1·2-418·7, P=0·039) were independent risk factors for anthrax in cattle.

Elucidation of the mechanistic pathways of the hydroxyl radical scavenging reaction by daidzein using hybrid QM/MM dynamics.

Employing a hybrid QM/MM simulation we explored the reaction dynamics of the hydroxyl radical scavenging activity of daidzein, a soy isoflavone. Our simulations illustrate that the highly reactive hydroxyl radical can participate in hydrogen abstraction reaction with both OH functional groups of daidzein and can form stable daidzein radicals. We found that the reaction involving the 4'-OH site of daidzein is energetically favorable over the other reaction pathway involving the 7-OH site of daidzein by ∼29 kcal/mol. The high enthalpic stabilization involved in daidzein radical formation at the 4'-OH site can be partly attributed to better solvation through hydrogen-bonding interactions with water and higher electron density delocalization of radical over the adjacent aromatic ring. As evident from the QM/MM dynamics, both HAT pathways led to formation of ketones at the 7-OH and 4'-OH sites of daidzein, respectively, and the adjacent aromatic rings appear in a p-quinonoid form, a highly stable resonating structure. The suitability of the QM/MM methodology to study the reaction mechanism, identification of intermediate states, and pathways of flavonoid radical stabilization reported here opens up a new possibility to study a similar reaction mechanism in other systems.

Multiscale QM/MM molecular dynamics study on the first steps of guanine damage by free hydroxyl radicals in solution.

Understanding the damage of DNA bases from hydrogen abstraction by free OH radicals is of particular importance to understanding the indirect effect of ionizing radiation. Previous studies address the problem with truncated DNA bases as ab initio quantum simulations required to study such electronic-spin-dependent processes are computationally expensive. Here, for the first time, we employ a multiscale and hybrid quantum mechanical-molecular mechanical simulation to study the interaction of OH radicals with a guanine-deoxyribose-phosphate DNA molecular unit in the presence of water, where all of the water molecules and the deoxyribose-phosphate fragment are treated with the simplistic classical molecular mechanical scheme. Our result illustrates that the presence of water strongly alters the hydrogen-abstraction reaction as the hydrogen bonding of OH radicals with water restricts the relative orientation of the OH radicals with respect to the DNA base (here, guanine). This results in an angular anisotropy in the chemical pathway and a lower efficiency in the hydrogen-abstraction mechanisms than previously anticipated for identical systems in vacuum. The method can easily be extended to single- and double-stranded DNA without any appreciable computational cost as these molecular units can be treated in the classical subsystem, as has been demonstrated here.

In silico design of peptidic inhibitors targeting estrogen receptor alpha dimer interface.

Human estrogen receptor alpha (ERα), which acts as a biomarker and as a therapeutic target for breast cancers, is activated by agonist ligands and co-activator proteins. Selective estrogen receptor modulators (SERM) act as antagonists in specific tissues and tamoxifen, a SERM, has served as a drug for decades for ERα-positive breast cancers. However, the ligand-selective and tissue-specific response of ERα biological activity and the resistance to tamoxifen treatment in advanced stages of ERα-positive breast cancers underscores the need to find a ligand-independent inhibitor for ERα. Here we present a ligand-independent approach of inhibiting ERα transactivation targeting its dimerization-a key process of ERα biological activity. Using in silico techniques, we first elucidated the hydrogen bond interactions involved in dimerization and identified three interfacial sequence motifs, where sequence I (DKITD) and sequence II (QQQHQRLAQ) of one monomer form hydrogen bonding with sequence II and sequence I of the second monomer, respectively, and sequence III (LSHIRHMSNK) hydrogen bonds with the same from the second monomer. Studying the structural stability and the binding affinity of the peptides derived from these sequence motifs, we found that an extended and ARG mutated version (LQQQHQQLAQ) of sequence II can act as a suitable template for designing peptidic inhibitors. It provides additional structural stability and interacts more strongly with ERα dimer interface groove formed by helices 9 and 10/11 and prevent ERα dimerization. Our result provides a novel therapeutic designing pipeline for ligand-independent inhibition of ERα.

Early Impact of Cardiopulmonary Bypass on Renal Function after Valve Replacement Surgery.

Renal dysfunction following cardiopulmonary bypass is well recognized. The pathophysiology of renal injury is multifactorial and culmination of the interplay of several pathophysiological mechanism. Cardiac surgery requiring cardiopulmonary bypass (CPB) is being carried out on an extended patient population of different age groups and undergoing complex surgical procedure, and thus it places them at an increased risk of renal impairment. Valve replacement surgery is a major and complex surgical procedure requiring CPB. This study was therefore designed to observe the impact of CPB and short term outcome on patients with reduced estimated Glomerular Filtration Rate (eGFR) (60-89ml/min/1.73m²) after valve replacement surgery. This cross-sectional study was conducted in the Department of Cardiac Surgery, National Institute of Cardio Vascular Diseases (NICVD) during the period of January 2015 to August 2016. After fulfillment of enrollment criteria 100 patients were studied for the purpose of the study and they were grouped in two, patients with normal eGFR (≥90ml/min/1.73m²) in Group A and patients with reduced eGFR (60-89ml/min/1.73m²) in Group B. A total of 100 patients, 50 in each group were studied for renal function alteration after valve replacement surgery under cardiopulmonary bypass. The incidence of Acute Kidney Injury (AKI) was higher in Group B. Chi-square test was done and p value was 0.011 which is statistically significant. Postoperative blood loss (ml/hr) (p=0.038), duration of Intensive Care Unit (ICU) stay (in hours) (p=0.009), postoperative hospital stay (days) (p=0.014) was significantly higher and postoperative Urine Output (ml/hr) (p=0.001) was significantly lower in patients with reduced eGFR (60-89ml/min/1.73m²) in Group B. Deterioration of renal function is more in patient with eGFR (60-89ml/min/1.73m²) after valve replacement surgery under cardiopulmonary bypass in comparison with patients with eGFR (≥90ml/min/1.73m²).

Mortality rate and clinical features of highly pathogenic avian influenza in naturally infected chickens in Bangladesh.

A retrospective study was performed to assess the mortality rates and clinical signs in commercial and backyard chickens naturally infected with the highly pathogenic avian influenza (HPAI) H5N1 virus in Bangladesh. All of the 33 commercial and 25 backyard farms, recorded during the first wave of HPAI outbreaks (January to November 2007) in Bangladesh, were enrolled in this study. The farm profile data, stock information and major clinical signs recognised by the farmers and/or farm attendants, were collected through a prototype questionnaire. The investigating veterinarians' retrospective appraisals of the clinical signs were recorded by interview. After the clinical onset, the incidence rates of mortality in breeder, commercial broiler, commercial layer and backyard chickens were, respectively: 0.0215, 0.0341, 0.0179 and 0.0703 per chicken-day at risk. The four major clinical signs observed were cyanotic combs and wattles, oedema of the head and face, drowsiness and huddling and ecchymotic discoloration of the leg shanks. The first sign (cyanotic combs and wattles) was equally observed in chickens from commercial and backyard farms (p = 0.44) but the second (oedema of the head and face) was more common in backyard farms (p = 0.03).

Chiral singlet superconductivity in the weakly correlated metal LaPt3P.

Chiral superconductors are novel topological materials with finite angular momentum Cooper pairs circulating around a unique chiral axis, thereby spontaneously breaking time-reversal symmetry. They are rather scarce and usually feature triplet pairing: a canonical example is the chiral p-wave state realized in the A-phase of superfluid He3. Chiral triplet superconductors are, however, topologically fragile with the corresponding gapless boundary modes only weakly protected against symmetry-preserving perturbations in contrast to their singlet counterparts. Using muon spin relaxation measurements, here we report that the weakly correlated pnictide compound LaPt3P has the two key features of a chiral superconductor: spontaneous magnetic fields inside the superconducting state indicating broken time-reversal symmetry and low temperature linear behaviour in the superfluid density indicating line nodes in the order parameter. Using symmetry analysis, first principles band structure calculation and mean-field theory, we unambiguously establish that the superconducting ground state of LaPt3P is a chiral d-wave singlet.

The space-time clustering of highly pathogenic avian influenza (HPAI) H5N1 outbreaks in Bangladesh.

Bangladesh faced two epidemic waves of highly pathogenic avian influenza (HPAI) H5N1 in two consecutive years. The peaks of the waves were observed in February-July 2007 and January-April 2008, respectively. We examined the spatial and temporal patterns of the 293 outbreaks in 143 subdistricts in 2007 and 2008. Global clustering assessed by K-function was seen at distances 150-300 km between subdistricts. Significant local clusters were detected by space-time scan statistics. In both waves, significant primary clusters of HPAI outbreaks were identified in the central part of the country dominated by commercial production systems and in the northwestern part primarily in backyard production systems. Secondary clusters varied from the northwestern part in 2007 and the southern part in 2008. The findings are highly relevant for the successful planning and implementation of control, prevention and surveillance strategies by highlighting areas where detailed investigations should be initiated.

Carcinoma gallbladder.

Carcinoma gallbladder (CaGb) is a rare disease. The aetiology of CaGb is yet not known. However the risk of CaGb is increased in anomalous pancreaticobiliary duct junction (APBDJ), gall stones, xanthogranulomatus cholecystitis, calcified or porcelain gallbladder, cholelithiasis with typhoid carriers, gallbladder adenoma, red meat consumption and tobacco uses. There are protective effects of vegetables on CaGb. Most of the cases present with advanced disease. In early carcinoma of a gallbladder sign and symptoms mimic benign disease. The diagnosis is established by ultrasonography, computerized tomography and guided fine needle aspiration cytology (FNAC). Biochemical tests are of very little value in making a diagnosis. The treatment depends on the clinical stage at presentation. Surgery offers the best chance of cure. In stage T1a, laparoscopic or open cholecystectomy alone is curative, and in T1b, cholecystectomy with hepatoduodenal lymph node dissection without combined resection of an adjacent organ is required. Segment S4a+5 hepatectomy combined with extrahepatic bile duct resection (BDR) and D2 lymph node dissection is a highly recommended operation for the treatment of T2 and T3 CaGb. The dye injection method is useful in determining the appropriate extent of hepatic resection for advanced CaGb. Resurgery is required only in those cases where tumour has invaded the serosa and/ or adjacent structures when diagnosed postoperatively. Biliary bypass is required for palliation. Prognosis depends on early diagnosis and appropriate surgical excision.