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A new hydrazone, ethyl Z-2-(pyridine-2yl-methylene)hydrazinecarboxylate (C9H11N3O2; Hpyec) and its metal complexes bis(ethyl Z-2-(pyridine-2yl-methylene)hydrazinecarboxylate)nickel(II) monohydrate, [Ni(pyec)2]·H2O (1) and bis(acetato)(ethyl Z-2-(pyridine-2yl-methylene)hydrazinecarboxylate)cadmium(II), [Cd(Hpyec)(CH3COO)2] (2), have been prepared by mechanochemical syntheses and characterized by elemental analysis, UV–vis, IR and NMR spectroscopies, TG-DTA, and solid state emission techniques. The X-ray single crystal structures of both complexes were determined. In 1, the Ni2+ ion is coordinated by two N,N,O-tridentate anionic ligands to generate a distorted cis-NiO2N4 octahedron. In 2, the cadmium ion is seven-coordinate by one neutral N,N,O-tridentate ligand and two chelating acetate ions to generate a very-distorted CdN2O5 pentagonal bipyramid with the Hpyec atoms occupying both axial and one equatorial site. Crystal data: 1, C18H22N6NiO5, M r = 461.12, monoclinic, P21/c, a = 10.8759(3) Å, b = 11.7055(4) Å, c = 16.8424(5) Å, β = 108.583(1)°, V = 2032.38(11) Å3, Z = 4, R(F) = 0.023, wR(F 2) = 0.065; 2, C13H17CdN3O6, M r = 423.69, monoclinic, Cc, a = 13.0215(10) Å, b = 15.8104(11) Å, c = 7.99(6) Å, β = 96.692(2)°, V = 1621.7(2) Å3, Z = 4, R(F) = 0.017, wR(F 2) = 0.038.

Supplementary data related to this article can be found at https://doi.org/10.1016/j.molstruc.2018.12.076.

A novel hydrazone, ethyl 4-(pyridine-4yl-methylene) hydrazinecarboxylate (C9H11N3O2; 4-py), and Cu(II) complex [Cu(4-py)2(CH3COO)2(H2O)] (1) were synthesized and characterized via elemental analysis, FT-IR, 1H NMR and 13C NMR spectral techniques. The structure of 1 was determined through single crystal X-ray diffraction. The structure consists of monomers in which copper is penta-coordinated through a distorted square pyramidal geometry. The pyridine nitrogen atoms of two monodentate 4-py ligands and oxygen atoms from two monodentate acetate anions form the basal plane. The apical site is occupied by a water molecule. Nano sized copper metal (∼5 nm) and copper oxide (∼10 nm) were separately prepared via thermal decomposition of the as-prepared copper complex by varying the atmospheric conditions under which the complex was calcined at 400 °C for 1 h. Powder x-ray diffraction (PXRD) patterns confirmed that the prepared Cu and CuO nanoparticles were of high purity and crystallinity. Hence, this complex could be used as a single solid-state precursor to prepare both Cu and CuO nanoparticles via low temperature decomposition under different atmospheric conditions.

Safety remains a central obstacle preventing widespread use of RL in the real world: learning new tasks in uncertain environments requires extensive exploration, but safety requires limiting exploration. We propose Recovery RL, an algorithm which navigates this tradeoff by (1) leveraging offline data to learn about constraint violating zones before policy learning and (2) separating the goals of improving task performance and constraint satisfaction across two policies: a task policy that only optimizes the task reward and a recovery policy that guides the agent to safety when constraint violation is likely. We evaluate Recovery RL on 6 simulation domains, including two contact-rich manipulation tasks and an image-based navigation task, and an image-based obstacle avoidance task on a physical robot. We compare Recovery RL to 5 prior safe RL methods which jointly optimize for task performance and safety via constrained optimization or reward shaping and find that Recovery RL outperforms the next best prior method across all domains. Results suggest that Recovery RL trades off constraint violations and task successes 2 - 20 times more efficiently in simulation domains and 3 times more efficiently in physical experiments. See https://tinyurl.com/rl-recovery for videos and supplementary material., RA-L and ICRA 2021. First two authors contributed equally

A new imidazole core unsymmetrical diamine monomer (4, 4′ (4, 5-diphenyl-1H-imidazol-1, 2-diyl) dianiline) was successfully synthesized and used as precursor to develop polyimide (PI). In addition, different weight percentages of octaaminophenyl silsesquioxane (NH2-POSS) were reinforced to form, respective, POSS–PI nanocomposites. The formation of polyimides and composites was confirmed by various spectral analyses in addition to their morphology studies by scanning electron microscopy and high-resolution transmission electron microscope. Further, the developed neat PI and POSS–PI nanocomposites were studied for their thermal, optical, dielectric and antimicrobial properties. Data resulted from different studies indicated that the incorporation of 10 wt% NH2-POSS into the PI matrix show higher glass transition temperature, higher thermal stability and better UV shielding behavior when compared to the neat PI matrix as well as other POSS–PI composites. Dielectric studies infer that the value of dielectric constant was decreased with increasing the weight percentages of NH2-POSS reinforcement and the lowest value of dielectric constant (k = 2.1) was obtained for 10 wt% POSS–PI hybrid nanocomposites in addition to its better antimicrobial behavior. Thus, the current study promises that the developed PI and POSS–PI can be used as a multifunctional composite in various high-performance applications.

Mercury (Hg) contamination of aquatic sites represents a serious risk for human health and the environment. Therefore, effective and rapid monitoring of Hg in aqueous samples is a challenge of timely importance nowadays. In the present study, a rapid and sensitive mercury sensor based on the fluorescence quenching of MoS2 nanosheets/DNA/silicon dot nanoassembly has been developed for the efficient detection of mercury(II) in aquatic environments. In this process, silicon dots were synthesized through one-step high-temperature calcinations and thermomagnesium reduction method at 900 °C using rice husk as a silicon source, which demonstrates superior photophysical properties and excitation-dependent fluorescence behavior. The interaction between MoS2 nanosheets/DNA/silicon dot nanoassembly and Hg2+ ions was studied using photoluminescence spectroscopy. The addition of Hg2+ ions to the assay solution induced the detachment of fluorescent probe from the surface of MoS2 nanosheets. Thus, the fluorescent probes sustained its fluorescence intensity. The developed sensor was tested on various concentrations of Hg2+ ions ranging from 0 to 1000 nM as well as on various metal ions. In addition, MoS2 nanosheets/DNA/silicon dot nanoassembly fluorescent Hg sensor efficiently detected the presence of Hg2+ ions in real-time water samples, which was comparably detected by the conventional atomic absorbance spectrometer (AAS). Overall, our results highlighted the high reliability of the present approach for environmental monitoring of Hg2+ ions, if compared to that of the customary method with a lowest detection limit of 0.86 nM.

The influence of solute-solvent interactions was realized at the crystal-solution interface on the end crystal morphology of the nonlinear optical monoclinic methyl-p-hydroxybenzoate (p- MHB) single crystal when growing from solutions with solvents of different in nature. Polar protic solvents such as methanol and ethanol and polar aprotic solvents such as acetone and ethyl acetate afforded p-MHB single crystals having a prismatic morphology and the nonpolar solvent toluene provided a crystal with columnar morphology. Because of the difference in their polar nature, these solvents show a significant difference in the solute solubility, rate of evaporation, level of supersaturation generated within the solution, time consumed for nucleation and growth rate along different crystallographic directions of the growing crystal. Slow evaporation method was employed for the growth of smaller size p-MHB single crystals from solutions with various solvents and a large dimensional p-MHB single crystal of size 45 × 42 × 62 mm3 was grown through seeded controlled cooling of the solution method. The results indicate that the nature of hydrogen bonding interactions exists between different crystal faces and the corresponding solvent molecules used in the present study caused a significant change in the end habit and morphology of crystals.

In the present work, a novel cardanol based benzoxazine was synthesised by reacting three different amines (aniline (CrAb), N,N-dimethylaminopropylamine (CrDb) and caprolactam modified N,N-dimethylaminopropylamine (CrCb)) with cardanol in the presence of formaldehyde under appropriate experimental conditions. The resulting benzoxazines were characterised for their molecular structure and thermal behaviour using different analytical methods. Among the different systems studied, the tertiary amine derivatives were found to reduce the curing temperature efficiently (CrAb-275 °C > CrDb-265 °C > CrCb-251 °C) and were confirmed by DSC analysis. These cardanol based CrAb benzoxazines were blended with conventional benzoxazines (Bzs) and bismaleimides (BMIs) as binary and ternary systems and their thermal properties were studied. Three different catalysts (4-hydroxy acetophenone, 4-aminophenol, and 4-hydroxyphenyl maleimide) were used to study the effect of lowering the curing temperature. Further, the prepared benzoxazines were reinforced with varying weight percentages (1, 3, 5 and 10 wt%) of bio-silica derived from rice husk to obtain hybrid composites. The dielectric studies of bio-silica reinforced cardanol benzoxazines infer that the values of dielectric constant decreased with increasing wt% of bio-silica. It was further observed that 10 wt% bio-silica reinforced cardanol benzoxazines show the lowest value of dielectric constant of 1.9 at 1 MHz. From the data obtained from the different studies, it is concluded that the blends of cardanol based benzoxazines can be used in the form of sealants, encapsulants, adhesives and matrices in the fields of microelectronics and automobile applications for better performance.

$$\hbox {Si}@\hbox {SiO}_{2}$$ core–shell nanoparticles were proposed for the development of fluorescent mercury sensor, which also offers a promising alternative to toxic quantum dots (QD)-based heavy metal detection tools. In this study, a sensitive fluorescent assay based on DNA-labelled $$\hbox {Si}@\hbox {SiO}_{2}$$ core–shell nanoparticles for the detection of mercury (II) in environmental samples was investigated. Probe DNA was conjugated on the surface of the $$\hbox {Si}@\hbox {SiO}_{2 }$$ core–shell nanoparticles via $$5^{\prime }$$ -terminal-SH (thiol group) reaction. The detection protocol was based on the DNA hybridization resulted from the formation of mercury-mediated (thymine– $$\hbox {Hg}^{2+}$$ –thymine) base pairs which leave a fluorescent QD on the surface of quartz glass. The synthesized $$\hbox {Si}@\hbox {SiO}_{2}$$ core–shell nanoparticle showed a broad emission peak with strong intensity in the UV range around 423 nm. Transmission electronic microscope (TEM) images confirmed the presence of a uniform core–shell structure with Si core nanoparticles with a particle size ranging from 70 to 80 nm and silica shell thickness of about $$10 \pm 2\,\hbox {nm}$$ . Overall, our findings highlighted that the developed assay can detect $$\hbox {Hg}^{2+ }$$ ions in aqueous solution as low as 0.92 nM concentration. In addition, the labelled $$\hbox {Si}@\hbox {SiO}_{2}$$ core–shell nanoparticles showed prominence sensitivity, acceptable precision, reproducibility and stability, and could be readily applied to environmental sampling systems for $$\hbox {Hg}^{2+}$$ monitoring.

Predicted temperature rise is likely to increase the risks of development and progression of renal/urologic anomalies for workers engaged in physically exerting and high-heat occupations.We conducted a cross-sectional study with 340 steelworkers engaged in moderate to heavy labour with ≥3 year's heat exposures and assessed Wet Bulb Globe Temperature (WBGT) and heat-strain indicators. We captured self-reported heat-strain and kidney symptoms using validated questionnaires and subjected 91 workers to renal ultrasound upon referral of an occupational health specialist to detect and confirm any structural renal anomalies/stones.The results show that heat exposures (Avg.WBGT = 33.2 °C ± 3.8 °C) exceeded the Threshold Limit Value (TLV) for 220 workers. 95% of the workers reported symptoms of heat strain and dehydration and significant associations between heat exposures, rise in Core Body Temperature (CBT) (p = 0.0001) and Urine Specific Gravity (USG) (p = 0.018) were observed. Of the 91 workers subjected to renal ultrasound, 33% were positive for kidney/ureteral stones (n = 25)other structural renal anomalies (n = 5). Renal/urologic anomalies were higher in the heat-exposed workers (AOR = 2.374; 95% C.I = 0.927 to 6.077; p = 0.072) 29% of workers were from exposed group and 4% were from unexposed group. Years of exposure to heat (≥5 vs5) were significantly associated with the risk of renal anomalies/calculi.The preliminary finding concludes that high-heat stress combined with a heavy workload and chronic dehydration are high-risk factors for adverse renal health and calls for the urgent need for cooling interventions, enhanced welfare facilities, and protective labour policies to avert adverse health consequences for few million workers in the climate change scenario.

In this paper, the experimental performance of a SS304 heat pipe under natural and forced convection modes using two different wick mesh sizes is reported. Deionised water was used as a working fluid with different heat inputs. The wick material is made up of SS303 with two mesh sizes (such as, 100 and 200 mesh). The heat pipe was positioned at three orientations (such as, horizontal, inclined, and vertical). During experiments, the ambient temperature was maintained at 30 ± 2°C. The results showed that the heat pipe at an inclined position of 45° has about 71% higher heat transfer coefficient with minimum thermal resistance when compared to the horizontal and vertical positions. Moreover, the results confirmed that, the heat pipe using wick with 200 mesh specification at inclined position is an optimal configuration when compared to other configurations.

A new hydrazinium(+1) salt of 3,5-pyrazoledicarboxylic acid (H2Pzdca) of formula, (N2H5)HPzdca·H2O (HPzdca is a hydrogen-3,5-pyrazoledicarboxylate anion), was prepared and characterized using elemental analysis, FT-IR spectroscopy, TG-DTA, and single-crystal X-ray diffraction analysis. The salt crystallized in the space group P21/c. The monoclinic unit cell of the title compound, N2H5 +·C5H4N2O4 −·H2O, is a molecular salt consisting of one mono-protonated hydrazine cation [hydrazinium(+1) cation], one singly deprotonated hydrogen-3,5-pyrazoledicarboxylate anion, and one solvent water molecule. The overall structure is a 3-D supramolecular network formed through extensive O–H…O and N–H…O hydrogen-bonding interactions. Although the H2Pzdca monohydrate exhibited a two-step (110 and 298 °C) decomposition, its salt had multiple-step decompositions. The free acid underwent only endothermic decomposition, while its hydrazinium salt underwent an endothermic decomposition, followed by sharp exothermic degradation to form a black residue as the end product.

New copper(II) complexes [Cu(Pytc)(Cl)2]·2H2O (1) and [Cu2(tzp)2(CH3COO)4] (2) (Pytc = tert-butyl 2-(pyridine-2yl-methylene)hydrazinecarboxylate; tzp = 1,2,3-triazolo[1,5-a]pyridine) were prepared and were characterized by elemental analysis, electron impact mass spectrometry, UV–visible spectroscopy, infrared spectroscopy, and photoluminescence studies. A single-crystal X-ray diffraction study of 2 revealed a paddle-wheel copper(II) acetate structure with tzp acting as a monodentate ligand coordinated axially. Pytc and the metal complexes showed emissive, antibacterial, and antifungal properties. Furthermore, 2 was demonstrated to be a solid-state single-source precursor to form Cu and CuO nanoparticles (NPs) under different atmospheric conditions. By transmission electron microscopy, the as-prepared nanoparticles were observed to be roughly spherical with average particle sizes of approximately 10–12 nm for Cu NPs and approximately 20–22 nm for CuO NPs. Furthermore, high crystallinity, high purity, and the single-phase nature of the as-prepared NPs were revealed by the powder X-ray diffraction pattern.

A new hydrazone-type ligand, methyl 4-(pyridine-4yl-methylene) hydrazinecarboxylate (C8H9N3O2; 4-pymc) and its Cu(II) complex [Cu(4-pymc)2(CH3COO)2(H2O)] (1) were prepared and characterized. The structure of 1 comprises monomers in which Cu is five-coordinated with a distorted square pyramidal structure. Oxygen atoms of two monodentate acetate anions and a pair of nitrogen atoms from pyridine rings form the basal plane. The apical position is filled by a water molecule. Further, the TEM images demonstrated successful preparation of both Cu (~35 nm) and CuO (~95 nm) nanoparticles (NPs) using the single source as-prepared Cu(II) complex via a thermal decomposition approach simply by changing the atmospheric conditions (i.e., vacuum and air atmospheres) under which the Cu(II) complex was calcined for 1 h at 400 °C. Furthermore, the TG-DTA studies indicate that 1 underwent endo- followed by exo-thermic decomposition to form CuO as the end residue in an air atmosphere. The production of Cu and CuO NPs was corroborated by powder x-ray diffraction (PXRD) analysis. The sharp and high intensity PXRD peaks of the calcined samples corroborated that the formed NPs had no impurity and high crystallinity. Furthermore, both ligand and Cu(II) complex showed photoluminescence properties. Also, we demonstrated that the prepared 1 can act as a single, solid-source precursor to form both Cu and CuO NPs.

New cobalt (II) complexes of general formula [Co(L) (NO3) (H2O)2]·NO3 (L = methyl 2-(pyridine-2yl-methylene) hydrazinecarboxylate, C8H9N3O2 (2-PYMC) (1) and ethyl 2-(pyridine-2yl-methylene) hydrazinecarboxylate, C9H11N3O2 (2-PYEC) (2), have been synthesized and characterized by elemental analysis, UV–vis, IR, and photoluminescence measurements. The crystal structures of 1 and 2 reveal the presence of CoN2O5 pentagonal-bipyramidal coordination polyhedra in each complex: the basal plane consists of an N, N, O-tridentate 2-PYMC/2-PYEC ligand and a chelating nitrate anion and the axial sites are occupied by water molecules. The crystal structures are consolidated by O–H⋯O and C–H⋯O hydrogen bonds.

A rapid and sensitive fluorescent sensor based on the MoS2 nanosheet/DNA/carbon dot nanoassembly has been developed towards the detection of mercury(II) present in environmental samples. Bio-carbon dots (CDs) having strong fluorescence maxima at 451 nm were synthesized via one-step treatment with honey under low temperature carbonization. These CDs were nearly spherical with good size distribution and excellent monodispersity, and the average sizes of CD were around 2–4 nm as evidenced from transmission electron microscopy. The conjugation of DNA strands on the surface of the carbon dots provided an efficient fluorescent probe. The fluorescence of the MoS2 nanosheet/DNA/carbon dot nanoassembly enhanced gradually with the increase in the concentration of Hg2+ ions and the detection limit was found to be 1.02 nM. Furthermore, the fluorescence intensity was found to be linear with the concentration of Hg2+ ions in the range from 0 to 10 nM and their respective coefficient of determination was found to be 0.93676 and 0.98178. The present MoS2 nanosheet/DNA/carbon dot nanoassembly is highly selective toward Hg2+ ions over a wide range of metal ions tested.

Contact-rich manipulation tasks in unstructured environments often require both haptic and visual feedback. However, it is non-trivial to manually design a robot controller that combines modalities with very different characteristics. While deep reinforcement learning has shown success in learning control policies for high-dimensional inputs, these algorithms are generally intractable to deploy on real robots due to sample complexity. We use self-supervision to learn a compact and multimodal representation of our sensory inputs, which can then be used to improve the sample efficiency of our policy learning. We evaluate our method on a peg insertion task, generalizing over different geometry, configurations, and clearances, while being robust to external perturbations. Results for simulated and real robot experiments are presented., Comment: ICRA 2019

We propose a neural multi-document summarization (MDS) system that incorporates sentence relation graphs. We employ a Graph Convolutional Network (GCN) on the relation graphs, with sentence embeddings obtained from Recurrent Neural Networks as input node features. Through multiple layer-wise propagation, the GCN generates high-level hidden sentence features for salience estimation. We then use a greedy heuristic to extract salient sentences while avoiding redundancy. In our experiments on DUC 2004, we consider three types of sentence relation graphs and demonstrate the advantage of combining sentence relations in graphs with the representation power of deep neural networks. Our model improves upon traditional graph-based extractive approaches and the vanilla GRU sequence model with no graph, and it achieves competitive results against other state-of-the-art multi-document summarization systems., In CoNLL 2017

Background Workers laboring in steel industries in tropical settings with high ambient temperatures are subjected to thermally stressful environments that can create well-known risks of heat-related illnesses and limit workers’ productivity. Methods A cross-sectional study undertaken in a steel industry in a city nicknamed “Steel City” in Southern India assessed thermal stress by wet bulb globe temperature (WBGT) and level of dehydration from urine color and urine specific gravity. A structured questionnaire captured self-reported heat-related health symptoms of workers. Results Some 90% WBGT measurements were higher than recommended threshold limit values (27.2–41.7°C) for heavy and moderate workloads and radiational heat from processes were very high in blooming-mill/coke-oven (67.6°C globe temperature). Widespread heat-related health concerns were prevalent among workers, including excessive sweating, fatigue, and tiredness reported by 50% workers. Productivity loss was significantly reported high in workers with direct heat exposures compared to those with indirect heat exposures (χ2 = 26.1258, degrees of freedom = 1, p