Large magnetoelectric coupling in nanoscale BiFeO3_3 from direct electrical measurements

We report the results of direct measurement of remanent hysteresis loops on nanochains of BiFeO$_3$ at room temperature under zero and $\sim$20 kOe magnetic field. We noticed a suppression of remanent polarization by nearly $\sim$40\% under the magnetic field. The powder neutron diffraction data reveal significant ion displacements under a magnetic field which seems to be the origin of the suppression of polarization. The isolated nanoparticles, comprising the chains, exhibit evolution of ferroelectric domains under dc electric field and complete 180$^o$ switching in switching-spectroscopy piezoresponse force microscopy. They also exhibit stronger ferromagnetism with nearly an order of magnitude higher saturation magnetization than that of the bulk sample. These results show that the nanoscale BiFeO$_3$ exhibits coexistence of ferroelectric and ferromagnetic order and a strong magnetoelectric multiferroic coupling at room temperature comparable to what some of the type-II multiferroics show at a very low temperature.Comment: 7 pages with 5 figures, published in Phys. Rev.

The development and validation of a scoring tool to predict the operative duration of elective laparoscopic cholecystectomy

Background: The ability to accurately predict operative duration has the potential to optimise theatre efficiency and utilisation, thus reducing costs and increasing staff and patient satisfaction. With laparoscopic cholecystectomy being one of the most commonly performed procedures worldwide, a tool to predict operative duration could be extremely beneficial to healthcare organisations. Methods: Data collected from the CholeS study on patients undergoing cholecystectomy in UK and Irish hospitals between 04/2014 and 05/2014 were used to study operative duration. A multivariable binary logistic regression model was produced in order to identify significant independent predictors of long (> 90 min) operations. The resulting model was converted to a risk score, which was subsequently validated on second cohort of patients using ROC curves. Results: After exclusions, data were available for 7227 patients in the derivation (CholeS) cohort. The median operative duration was 60 min (interquartile range 45–85), with 17.7% of operations lasting longer than 90 min. Ten factors were found to be significant independent predictors of operative durations > 90 min, including ASA, age, previous surgical admissions, BMI, gallbladder wall thickness and CBD diameter. A risk score was then produced from these factors, and applied to a cohort of 2405 patients from a tertiary centre for external validation. This returned an area under the ROC curve of 0.708 (SE = 0.013, p  90 min increasing more than eightfold from 5.1 to 41.8% in the extremes of the score. Conclusion: The scoring tool produced in this study was found to be significantly predictive of long operative durations on validation in an external cohort. As such, the tool may have the potential to enable organisations to better organise theatre lists and deliver greater efficiencies in care

Spontaneous exchange bias in a nanocomposite of BiFeO3-Bi2Fe4O9

We have observed a large as well as path-dependent spontaneous exchange bias (H-SEB) (similar to 30-60 mT) in a nanocomposite of BiFeO3-Bi2Fe4O9 across 5-300K when it is measured in an unmagnetized state following zero-field cooling and appropriate demagnetization. The path dependency yields a variation in the exchange bias depending on the sign of the starting field and the path followed in tracing the hysteresis loop. The asymmetry thus observed-Delta H-SEB-is found to be decreasing nonmonotonically across 5-300K with a peak around 200K. The Delta H-SEB together with large H-SEB could have significant ramification in tuning the exchange bias driven effects and consequent applications. (c) 2013 American Institute of Physics

Ring opening of activated cyclopropanes with NIS/NaN3: synthesis of C-1 linked pseudodisaccharides

NIS/NaN3 mediated ring opening of various donor-acceptor cyclopropanes has been investigated. The study shows the necessity of the donor oxygen lone pair in such ring opening reactions. This methodology has been utilized in the synthesis of C-1 linked pseudodisaccharides through the use of click chemistry. (C) 2013 Elsevier Ltd. All rights reserved

A Review on Advances in Biocontrol Techniques for Managing Insect Pests in Sustainable Agriculture

Biocontrol techniques represent a vital avenue in the quest for sustainable agricultural practices. This approach, integrating ecological intelligence with modern scientific advancements, is seeing increasing adoption in various regions, notably in India. Drawing inspiration from nature's own mechanisms, biocontrol employs specific organisms or their biological derivatives to manage and mitigate pests, thereby decreasing the dependency on chemical agents. Through an in-depth exploration of biocontrol applications, this study places a special emphasis on India's initiatives and contrasts them with global endeavors. Noteworthy examples include the innovative use of parasitic wasps to combat the papaya mealybug menace in Tamil Nadu, the strategic application of fungi like Trichoderma for disease control in Maharashtra, and the successful introduction of parasitoid wasps to manage olive flies in regions like California. Rooted in foundational ecological principles, these methodologies exhibit potential benefits that span improved crop yields, economic viability, and most importantly, reduced environmental adversities. Effective deployment and scaling of these techniques require an integrated approach, emphasizing collaboration among researchers, farming communities, and industry stakeholders. By presenting a detailed analysis of these synergistic efforts, this review accentuates the transformative potential of biocontrol. As the global community faces the dual challenges of an expanding population and the unpredictable impacts of climate change, the promise of biocontrol looms large, offering a sustainable pathway for the agriculture of the future

Nanoindentation and nanowear study of Sn and Ni-Sn coatings

As potential high capacity anode materials for lithium ion batteries, the Sn and Ni-Sn alloy coatings have been investigated by many electrochemical researchers. However, their mechanical properties have not been extensively studied, despite the fact that such anode films may fail mechanically during service. Thus, in this study nanoindentation and nanowear tests have been performed. Nanoindentation tests reveal that the ability to carry the load dramatically reduces in the Sn coating after one charge-discharge cycle which makes the plastic strain accumulation in the copper substrate play a greater contribution to crack formation and propagation in repeated charge-discharge cycling. Upon the nanoindentation analysis, it also shows that the pores formed by lithiation/delithiation can easily collapse at low loads. Furthermore, nanowear tests explore that the damage resistance of the Sn-Ni alloy film significantly improves after one charge-discharge cycle but it decreases in the Sn film after the same charge-discharge cycle; this explains why the degradation rate of the Ni-Sn alloy is slow after the first charge-discharge cycle and why the high capacity is maintained in further cycling. The links between the mechanical characterization and the degradation in charge-discharge cycling are also discussed