Design and control of jumping microrobots with torque reversal latches.

Jumping microrobots and insects power their impressive leaps through systems of springs and latches. Using springs and latches, rather than motors or muscles, as actuators to power jumps imposes new challenges on controlling the performance of the jump. In this paper, we show how tuning the motor and spring relative to one another in a torque reversal latch can lead to an ability to control jump output, producing either tuneable (variable) or stereotyped jumps. We develop and utilize a simple mathematical model to explore the underlying design, dynamics, and control of a torque reversal mechanism, provides the opportunity to achieve different outcomes through the interaction between geometry, spring properties, and motor voltage. We relate system design and control parameters to performance to guide the design of torque reversal mechanisms for either variable or stereotyped jump performance. We then build a small (356 mg) microrobot and characterize the constituent components (e.g. motor and spring). Through tuning the actuator and spring relative to the geometry of the torque reversal mechanism, we demonstrate that we can achieve jumping microrobots that both jump with different take-off velocities given the actuator input (variable jumping), and those that jump with nearly the same take-off velocity with actuator input (stereotyped jumping). The coupling between spring characteristics and geometry in this system has benefits for resource-limited microrobots, and our work highlights design combinations that have synergistic impacts on output, compared to others that constrain it. This work will guide new design principles for enabling control in resource-limited jumping microrobots.

Zinc-Substituted Cobalt Phosphate [ZnCo2(PO4)2] as a Bifunctional Electrocatalyst.

Development of highly efficient, earth-abundant, and stable bifunctional electrocatalysts is pivotal for designing viable next-generation metal-air batteries. Cobalt-based phosphates provide a treasure house to design electrocatalysts, with a wide range of cation substitutions to further enhance their electrocatalytic activity. In particular, phosphates with distorted geometry show favorable binding efficiency toward water molecules with low overpotential. In the present work, zinc-substituted cobalt phosphate ZnCo2(PO4)2 was investigated. Its crystal structure was solved to a monoclinic framework built with CoO6 octahedra and distorted CoO5/ZnO5 trigonal bipyramid leading to efficient bifunctional electrocatalytic activity. It offers robust structural stability with onset potential values of 0.87 V (vs reversible hydrogen electrode (RHE)) and 1.50 V (vs RHE) for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) processes, respectively, comparable to the precious metal catalysts. The origin and stability of the bifunctional activity were probed by combining ex situ diffraction and electron microscopy corroborated by ab initio calculations. Overall, zinc-substituted cobalt phosphate [ZnCo2(PO4)2] forms a potential bifunctional electrocatalyst with tunable local cobalt coordination that can be harnessed for metal-air batteries.

Delivering surgical education: a specialist surgical society and undergraduate student collaboration.

Currently, the delivery of the undergraduate medical curriculum includes various teaching, learning and assessment strategies. Self-directed learning is an important aspect of this mix and includes the use of resources, sometimes not provided by the parent University, in the student's own time to enhance the student's knowledge, skills and professional practice. Societies aimed at a particular specialty contain a pool of professionals that can provide undergraduate students with opportunities for further self-directed learning, development of specialty-specific core skills and exploration of research interests. This may then enhance and enlighten the students' approach to a particular orthopaedic problem and reinforce the curriculum they are studying while providing an understanding of current areas of debate that are not part of the curriculum at present. The collaboration of postgraduate societies with undergraduate students in developing and implementing undergraduate engagement strategies is of benefit to undergraduate education, the specialty society and the collaborating students. We explore the planning and implementation of an interactive webinar series run by the British Indian Orthopaedic Society in collaboration with undergraduate students. We provide a case study of a surgical specialty society engaging with undergraduate students with synergistic effect. We pay particular attention to the benefits accrued by the specialty society and the student collaborators by this joint effort.

Toxicity assessment of common acaricides and mineral oils on Anagyrus vladimiri, an effective biocontrol agent of citrus mealybug.

Chemical pesticides, while playing an important role in the suppression of insect pests, should be used in a manner that minimizes negative effects on natural enemies. The parasitoid, Anagyrus vladimiri Triapitsyn (Hymenoptera: Encyrtidae), plays an important role in the management of mealybug pests of citrus groves in the Mediterranean region. This study was conducted to evaluate the effect of commonly used acaricides (Spirodiclofen, Spirotetramat, Sulfur, Fenpyroximate, Abamectin) and mineral oils (Levanola, EOS, JMS, and Ultrapaz) on acute mortality of A. vladimiri. Toxicity was assessed in 4 cases: (i) direct spray application on adults, (ii) pesticide application on the mummified host, (iii) feeding with contaminated food, and (iv) contact with pesticide residue. The pesticide Abamectin, applied alone and with Levanola oil was highly toxic to adults in all bioassays, with the exception of direct spray application on the mummified host. Fenpyroximate was found to be highly toxic only when sprayed directly on adults, and sulfur was slightly harmful. Mineral oils were harmful when ingested with food; otherwise, they did not cause appreciable adult mortality. The findings of the present study suggest that all tested materials, with the exception of Abamectin and Fenpyroximate, are compatible with the survival of A. vladimiri. Direct ingestion of oils can, however, cause a degree of mortality. Given that indiscriminate use of these pesticides may affect the population ecology of A. vladimiri, they should be used with caution.

First principles investigation of anionic redox in bisulfate lithium battery cathodes.

The search for an alternative high-voltage polyanionic cathode material for Li-ion batteries is vital to improve the energy densities beyond the state-of-the-art, where sulfate frameworks form an important class of high-voltage cathode materials due to the strong inductive effect of the S6+ ion. Here, we have investigated the mechanism of cationic and/or anionic redox in LixM(SO4)2 frameworks (M = Mn, Fe, Co, and Ni and 0 ≤ x ≤ 2) using density functional calculations. Specifically, we have used a combination of Hubbard U corrected strongly constrained and appropriately normed (SCAN+U) and generalized gradient approximation (GGA+U) functionals to explore the thermodynamic (polymorph stability), electrochemical (intercalation voltage), geometric (bond lengths), and electronic (band gaps, magnetic moments, charge populations, etc.) properties of the bisulfate frameworks considered. Importantly, we find that the anionic (cationic) redox process is dominant throughout delithiation in the Ni (Mn) bisulfate, as verified using our calculated projected density of states, bond lengths, and on-site magnetic moments. On the other hand, in Fe and Co bisulfates, cationic redox dominates the initial delithiation (1 ≤ x ≤ 2), while anionic redox dominates subsequent delithiation (0 ≤ x ≤ 2). In addition, evaluation of the crystal overlap Hamilton population reveals insignificant bonding between oxidized O atoms throughout the delithiation process in the Ni bisulfate, indicating robust battery performance that is resistant to irreversible oxygen evolution. Finally, we observe that both GGA+U and SCAN+U predictions are in qualitative agreement for the various properties predicted. Our work should open new avenues for exploring lattice oxygen redox in novel high voltage polyanionic cathodes, especially using the SCAN+U functional.

Pyrophosphate Na2CoP2O7 Polymorphs as Efficient Bifunctional Oxygen Electrocatalysts for Zinc-Air Batteries.

Developing earth-abundant low-cost bifunctional oxygen electrocatalysts is a key approach to realizing efficient energy storage and conversion. By exploring Co-based sodium battery materials, here we have unveiled nanostructured pyrophosphate Na2CoP2O7 polymorphs displaying efficient bifunctional electrocatalytic activity. While the orthorhombic polymorph (o-NCPy) has superior oxygen evolution reaction (OER) activity, the triclinic polymorph (t-NCPy) delivers better oxygen reduction reaction (ORR) activity. Simply by tuning the annealing condition, these pyrophosphate polymorphs can be easily prepared at temperatures as low as 500 °C. The electrocatalytic activity is rooted in the Co redox center with the (100) active surface and stable structural framework as per ab initio calculations. It marks the first case of phospho-anionic systems with both polymorphs showing stable bifunctional activity with low combined overpotential (ca. ∼0.7 V) comparable to that of reported state-of-the-art catalysts. These nanoscale cobalt pyrophosphates can be implemented in rechargeable zinc-air batteries.

Facile synthesis and phase stability of Cu-based Na2Cu(SO4)2·xH2O (x = 0-2) sulfate minerals as conversion type battery electrodes.

Mineral exploration forms a key approach for unveiling functional battery electrode materials. The synthetic preparation of naturally found minerals and their derivatives can aid in designing of new electrodes. Herein, saranchinaite Na2Cu(SO4)2 and its hydrated derivative kröhnkite Na2Cu(SO4)2·2H2O bisulfate minerals have been prepared using a facile spray drying route for the first time. The phase stability relation during the (de)hydration process was examined synergising in situ X-ray diffraction and thermochemical studies. Kröhnkite forms the thermodynamically stable phase as the hydration of saranchinaite to kröhnkite is highly exothermic (-51.51 ± 0.63 kJ mol-1). Structurally, kröhnkite offers a facile 2D pathway for Na+ ion migration resulting in 20 times higher total conductivity than saranchinaite at 60 °C. Both compounds exhibited a conversion redox mechanism for Li-ion storage with the first discharge capacity exceeding 650 mA h g-1 (at 2 mA g-1vs. Li+/Li) upon discharge up to 0.05 V. Post-mortem analysis revealed that the presence of metallic Cu in the discharged state is responsible for high irreversibility during galvanostatic cycling. This study reaffirms the exploration of Cu-based polyanionic sulfates, which while having limited (de)insertion properties, can be harnessed for conversion-based electrode materials for batteries.

Crystal and Magnetic Structures of Monoclinic FeOHSO4.

The crystal and magnetic structures and properties of the monoclinic form of the iron hydroxysulfate FeOHSO4 were investigated by magnetometry and neutron powder diffraction. The space group C2/c was confirmed, and the proton position was located close to that predicted by ab initio calculations. The collinear antiferromagnetic k(0,0,0) structure forming below the Néel temperature TN ∼ 125 K is described by the C2'/c' (No. 15.89) magnetic space group, with the moments along the b axis. Overall, FeOHSO4 is isostructural to FeSO4F in terms of both the crystal and magnetic structures.

An overview of hydroxy-based polyanionic cathode insertion materials for metal-ion batteries.

Rechargeable batteries based on Li-ion and post Li-ion chemistry have come a long way since their inception in the early 1980s. The last four decades have witnessed steady development and discovery of myriads of cathode materials taking into account their processing, economy, and performance along with ecological sustainability. Though oxides rule the battery sector with their high energy and power density, polyanionic insertion compounds work as gold mines for designing insertion compounds with rich structural diversity leading to tuneable redox potential coupled with high structural/chemical/thermal stability. The scope of polyanionic compounds can be taken a step further by combining two or more different types of polyanions to get suites of mixed polyanionic materials. While most cathodes are built with metal polyhedra constituted by oxygen (MOm|XOm, M = 3d metals, X = P, S, Si, B, W, etc., m = 3-6), in some cases, selected oxygen sites can form bonding with hydrogen to form OH/H2O ligands. It can lead to the family of hydroxy-based mixed-polyanionic cathode materials. The presence of hydroxy components can affect the crystal structure, local chemical bonding, and electronic, magnetic, diffusivity and electrochemical properties. Employing a mineralogical survey, the current review renders a sneak peek on various hydroxy-based polyanionic cathode materials for Li-ion and post Li-ion batteries. Their crystal structure, and electrochemical properties have been overviewed to outline future research focus and scope for real-life application.

Mild mitochondrial uncoupling protects from ionizing radiation induced cell death by attenuating oxidative stress and mitochondrial damage.

Ionizing radiation (IR) induced mitochondrial dysfunction is associated with enhanced radiation stimulated metabolic oxidative stress that interacts randomly with intracellular bio-macromolecules causing lethal cellular injury and cell death. Since mild mitochondrial uncoupling emerged as a valuable therapeutic approach by regulating oxidative stress in most prevalent human diseases including ageing, ischemic reperfusion injury, and neurodegeneration with comparable features of IR inflicted mitochondrial damage. Therefore, we explored whether mitochondrial uncoupling could also protect from IR induced cytotoxic insult. Our results showed that DNP, BHT, FCCP, and BAM15 are safe to cells at different concentrations range depending on their respective mitochondrial uncoupling potential. Pre-incubation of murine fibroblast (NIH/3T3) cells with the safe concentration of these uncouplers followed by gamma (γ)-radiation showed significant cell growth recovery, reduced ROS generation, and apoptosis, compared to IR treatment alone. We observed that DNP pre-treatment increased the surviving fraction of IR exposed HEK-293, Raw 264.7 and NIH/3T3 cells. Additionally, DNP pre-treatment followed by IR leads to reduced total and mitochondrial oxidative stress (mos), regulated calcium (Ca2+) homeostasis, and mitochondrial bioenergetics in NIH/3T3 cells. It also significantly reduced macromolecular oxidation, correlated with the regulated ROS generation and antioxidant defence system. Moreover, DNP facilitated DNA repair kinetics evidenced by reducing the number of γ-H2AX foci formation and fragmented nuclei with time. DNP pre-incubation restrained the radiation induced pro-apoptotic factors and inhibits apoptosis. Our findings raise the possibility that mild mitochondrial uncoupling with DNP could be a potential therapeutic approach for radiation induced cytotoxic insult associated with an altered mitochondrial function.

Retrospective Analysis of Arthrodesis from Various Options after Anterior Cervical Discectomy.

INTRODUCTION: Anterior cervical discectomy is a surgical procedure performed to treat a herniated/degenerated disc in the cervical region. There have been various studies comparing arthrodesis rates among various procedures. Our patients belonged to varied socioeconomic background and underwent anterior cervical microdiscectomy without/with instrumentation. AIM: The present study was performed to study and compare the arthrodesis rates in the patients operated for anterior cervical microdiscectomy with and without fusion/instrumentation procedures at our institution. MATERIALS AND METHODS: This is a retrospective study performed at Vydehi Institute of Medical Sciences and Research Centre, Bengaluru. Pre- and post-operative X-rays were assessed in 96 patients who had undergone anterior cervical discectomy with/without fusion from June 2012 to June 2015. Radiographic arthrodesis was assessed in all patients. An arbitrary grading was designed by us and categorized into Grade I to IV. The criteria considered for adequate arthrodesis in this study were: (a) <2° movement on dynamic X-rays, (b) restored disc space height (±2 mm accepted), and (c) evidence of solid bone mass around disc space. Arthrodesis was categorized as Grade I if all the above 3 criteria on X-rays was fulfilled, Grade II if any 2 of the criteria was fulfilled, Grade III if any 1 of the criteria was fulfilled, and Grade IV when pseudoarthrosis/none of the criteria was fulfilled. Grade I arthrodesis was noted in about 79 patients (82.2%), Grade II in 14 patients, and only 3 patients had Grade III arthrodesis. There were no patients with absent arthrodesis/pseudoarthrosis. RESULTS: Satisfactory arthrodesis was noted in 82% of the total patients, with patients undergoing fusion ± instrumentation procedure having better results. CONCLUSIONS: Arthrodesis by an interbody graft/implant with/without plating increases chances of success as compared to anterior cervical discectomy alone. Patients should be motivated for any of the available options for fusion/instrumentation.

Plasticity in reproductive output and development in response to thermal variation in ladybird beetle, Menochilus sexmaculatus.

All organisms are exposed to daily as well as seasonal variation in temperature in nature. However, ectotherms are strongly affected by temperature and its variations. Most laboratory studies on effect of temperature on life history traits employ constant instead of fluctuating temperature regimes, though the latter is more reflective of nature. We conducted investigations on the effect of constant, fluctuating and alternate temperature regimes on reproductive and developmental attributes of a biocontrol agent ladybird, Menochilus sexmaculatus (Fabricius) (Coleoptera: Coccinellidae). We used three constant, viz. cold, optimum and hot (15°C, 27°C and 35°C); two fluctuating with variation in mean temperature of the day (15°C/27°C, 35°C /27°C; 10/14h) and three alternating (15°C/27°C, 35°C/27°C, 15°C/35°C; 24/24h) temperatures to evaluate their effects on these life attributes. Oviposition and percent egg viability along with offspring development (immature life stages developmental time and developmental rate) and elytral colouration pattern of adults were observed. The best response in terms of oviposition and percent egg viability was recorded at the constant temperature of 27°C followed by the fluctuating regime with a mean temperature of 30.3°C. The fastest development was found at a constant temperature of 35°C, followed by a fluctuating temperature of 35°C/27°C for 10/14h. Among the different temperature cycles, the most uncustomary trend of oviposition and percent egg viability was recorded on an alternate temperature of 15°C/35°C for 24/24h. The constant (27°C) and fluctuating (35°C/27°C for 10/14h) temperatures caused an incremental effect on reproductive output and developmental rate. This study demonstrates that M. sexmaculatus is able to adjust its physiology according to surrounding environmental conditions and acclimatizes well with the fluctuating/alternate temperatures suggesting its wide range of tolerance. The findings of present work would be helpful in augmenting population dynamics of this biocontrol agent to suppress insect pest.