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Convolution codes are widely used error correction codes in wireless communication systems. In recursive non-systematic codes, the output of the encoder is more dependent on the previous input bits. Hence, the weight factor of the coded data increases that lead to improvement in the performance of the transmission system. The paper proposes two schemes for making the feedback connections to the recursive convolution encoder. Using these schemes, different feedback connections can be provided to the encoder for improving the performance of the system. The first scheme implements a tri-state buffer with synchronous counters in the feedback connection, and in the second scheme, a negative feedback is provided to the encoder using a NOT gate. Simulations are done using MATLAB software. The two schemes are studied using 16, 32 QAM and 16 PSK modulation schemes over AWGN channel. The results show that the first scheme leads to decrease in the Bit Error Rate (BER) as compared to conventional scheme, and the second scheme has been able to achieve the performance of conventional system. [ABSTRACT FROM AUTHOR]

Background: Glass-ionomer cement (GIC) was introduced in the 1970s by Wilson and Kent. Initial conventional GICs had some disadvantages, so polymerizable functional groups were added to their structure in order to improve the clinical application and physical and chemical properties of conventional GICs, which yielded resin-modified glass-ionomer cements (RMGICs). Aim of the study: To assess micro-shear bond strength of resin modified glass-ionomer to composite resins using various bonding systems. Materials and methods: The present study was conducted in the Department of Conservative Dentistry of the dental institutions. In the present study, we compared GIC and composite resin. A total of 40 specimens of each of the material were fabricated for evaluation. The GIC was manipulated, inserted into acrylic artificial cavities (0.2 cm depth x 1 height x 1 cm width), and pressed with a Mylar strip and a glass slide to protect the material and ensure a smooth surface. Half of the specimens in each group were submitted to a micro-shear test in a universal testing machine with a 50 kgf load cell at a crosshead speed of 0.5 mm/min. The other half was subjected to aging in a thermal cycler and then the micro-shear test. All samples were analyzed in the stereomicroscope at x 10 magnification to evaluate the interfacial fracture and classified as adhesive, cohesive, or mixed. Results: We observed that the micro shear bond strength of composite was more as compared to GIC in both the stages. The shear bond strength of both the materials decreased significantly after thermal cycling. Conclusion: Within the limitations of the present study, it can be concluded that the micro-shear bond strength of composite resin to GIC was higher. [ABSTRACT FROM AUTHOR]

Aerobic reaction of the ligand H2L1, 2-(2-phenylazo)-anilino-4,6-di-tert-butylphenol, CoCl2·6H2O and Et3N in MeOH under refluxing conditions produces, after work-up and recrystallization, black crystals of [Co(L1)2] (1). When examined by cyclic voltammetry, 1 displays in CH2Cl2 three one-electron redox responses: two oxidative, E11/2 = 0.30 V (peak-to-peak separation, ΔEp = 100 mV) and E21/2 = 1.04 V (ΔEp = 120 mV), and one reductive E1/2 = −0.27 V (ΔEp = 120 mV) vs. SCE. Consequently, 1 is chemically oxidized by 1 equiv. of [FeIII(η5-C5H5)2][PF6], affording the isolation of deep purple crystals of [Co(L1)2][PF6]·2CH2Cl2 (2), and one-electron reduction with [CoII(η5-C5H5)2] yielded bluish-black crystals of [CoIII(η5-C5H5)2][Co(L1)2]·MeCN (3). A solid sample of 1 exhibits temperature-independent (50–300 K) magnetism, revealing the presence of a free radical (S = 1/2), which exhibits an isotropic EPR signal (g = 2.003) at 298 K and at 77 K an eight-line feature characteristic of hyperfine-interaction of the radical with the Co (I = 7/2) nucleus. Based on X-ray structural parameters of 1–3 at 100 K, magnetic and EPR spectral behaviour of 1, and variable-temperature (233–313 K) 1H NMR spectral features of 1–3 and 13C NMR spectra at 298 K of 2 and 3 in CDCl3 point to the electronic structure of the complexes as either [CoIII{(LAP)2−}{(LISQ)}Ṗ−] or [CoIII{(L1)2}Ṗ3−] (delocalized nature favours the latter description) (1), [CoIII{(LISQ)Ṗ−}2][PF6]·2CH2Cl2 (2) and [CoIII(η5-C5H5)2][CoIII{(LAP)2−}2]·MeCN (3) [(LAP)2− and (LISQ)Ṗ− represent the redox-level of coordinated ligands o-amidophenolate(2−) ion and o-iminobenzosemiquinonate(1−) π-radical ion, respectively]. Notably, all the observed redox processes are ligand-centred. To the best of our knowledge, this is the first time that six-coordinate complexes of a common tridentate o-aminophenolate-based ligand have been structurally characterized for the parent 1, its monocation 2 and the monoanion 3 counterparts. Temperature-dependent 1H NMR spectra reveal the existence of valence-tautomeric equilibria in 1–3. Density Functional Theory (DFT) calculations at the B3LYP-level of theory corroborate the electronic structural assignment of 1–3 from experimental data. The origins of the observed UV–VIS–NIR absorptions for 1–3 have been assigned, based on time-dependent (TD)-DFT calculations. [ABSTRACT FROM AUTHOR]

Copper plays key roles in catalytic and regulatory biochemical reactions essential for normal growth, development, and health. Dietary copper deficiencies or mutations in copper homeostasis genes can lead to abnormal musculoskeletal development, cognitive disorders, and poor growth. In yeast and mammals, copper is acquired through the activities of the CTR1 family of high-affinity copper transporters. However, the mechanisms of systemic responses to dietary or tissue-specific copper deficiency remain unclear. Here, taking advantage of the animal model Caenorhabditis elegans for studying whole-body copper homeostasis, we investigated the role of a C. elegans CTR1 homolog, CHCA-1, in copper acquisition and in worm growth, development, and behavior. Using sequence homology searches, we identified 10 potential orthologs to mammalian CTR1. Among these genes, we found that chca-1, which is transcriptionally up-regulated in the intestine and hypodermis of C. elegans during copper deficiency, is required for normal growth, reproduction, and maintenance of systemic copper balance under copper deprivation. The intestinal copper transporter CUA-1 normally traffics to endosomes to sequester excess copper, and we found here that loss of chca-1 caused CUA-1 to mislocalize to the basolateral membrane under copper overload conditions. Moreover, animals lacking chca-1 exhibited significantly reduced copper avoidance behavior in response to toxic copper conditions compared with WT worms. These results establish that CHCA-1-mediated copper acquisition in C. elegans is crucial for normal growth, development, and copper-sensing behavior. [ABSTRACT FROM AUTHOR]

The accurate measurement of tool tip temperature in turning has been a challenging task for researchers. The present study covers the computational fluid dynamics (CFD) analysis of a single point carbide cutting tool dissipating heat and subjected to streams of nanofluid mist. This study is an attempt to numerically analyze the thermal behavior of the cutting tool having constant temperature heat source at its tip. To determine the optimized experimental value of nodal temperature, machining of AISI 304 steel has been carried out using alumina and alumina-MWCNT hybrid nanofluid mist with minimum quantity lubrication (MQL) system. Furthermore, the conjugate heat transfer (CHT) analysis has been performed to investigate the temperature distribution over the rake and flank face of carbide cutting insert. An overview of the mathematical model, complete geometry, and mesh generation of the carbide cutting tool is presented. Additionally, the CHT simulation results for the mist of alumina and alumina-MWCNT hybrid nanofluids were compared and validated successfully with the experimental data. The maximum variation of 5.79% has been observed between experimental and simulation data, which in turn proves the proposed conjugate heat transfer-based CFD model as an alternative approach to investigate the influence of cooling media on cutting tool under MQL technique. [ABSTRACT FROM AUTHOR]

Present work investigates the effect of alumina/graphene (GnP) hybrid nanoparticle additives on tribological properties of lubricant as cutting fluid in turning of AISI 304 steel. The hybrid nano-lubricant has been developed in different volumetric concentrations (0.25, 0.75 and 1.25 vol%). The tribology and wettability testing of lubricants confirm that wear and friction coefficient reduces with an increase of nanoparticle concentration. The hybrid nanofluid has shown the lowest pin wear and friction coefficient. The performance of hybrid nano-lubricant have been compared with the alumina nanofluid. The results establish that mixing of GnP with alumina enhanced its tribological properties. The developed hybrid nano-lubricant significantly reduced the tool flank wear and nodal temperature by 12.29% and 5.79%, respectively compare to alumina based lubricant. [ABSTRACT FROM AUTHOR]

Shape memory alloys (SMAs) have become the most common choice for the development of mini- and micro-type soft bio-inspired robots due to their high power-to-weight ratio, ability to be installed and operated in limited space, silent and vibration-free operation, biocompatibility, and corrosion resistance properties. Moreover, SMA spring-type actuators are used for developing different continuum robots, exhibiting high degrees of freedom and flexibility. Spring- or any elastic-material-based antagonistic or biasing force is mostly preferred among all other biasing techniques to generate periodic oscillation of SMA actuator-based robotic body parts. In this model-based study, SMA-based spring-type actuators were used to develop a carangiform-type robotic fishtail. Fin size optimization for the maximization of forward thrust was performed for the developed system by varying different parameters, such as caudal fin size, current through actuators, pulse-width modulation signal (PWM), and operating depth. A caudal fin with a mixed fin pattern between the Lunate and Fork "Lunafork" and a fin area of approximately 5000 mm2 was found to be the most effective for the developed system. The maximum forward thrust developed by this fin was recorded as 40 gmf at an operation depth of 12.5 cm in a body of still water. [ABSTRACT FROM AUTHOR]

A hybrid nanofluid (NF) with better thermal and tribological properties has been developed in this investigation by mixing alumina-based nanofluid with graphene nanoplatelets (GnP) in the volumetric concentrations of 0.25, 0.75 and 1.25 vol %. It was noted that an increase of nanoparticle concentration enhances both, the thermal conductivity and viscosity, though the hybrid nanofluid has lower thermal conductivity compare to its constituents and the viscosity lies in between its constituents. The tribological test confirms that the wear decreases with the increase of nanoparticle concentration and the hybrid nanofluid generated least amount of wear. Hybrid nanofluid shows better wettability results as compared to alumina-based nanofluid as well as base fluid. The turning of AISI 304 steel under minimum quantity lubrication (MQL) technique clearly establishes that application of hybrid nanofluid performs better as compared to alumina nanoparticle mixed cutting fluid. The study reveals that blending of GnP with alumina enhances the performance of hybrid nanofluids. The application of hybrid nanofluid with MQL significantly reduces the surface roughness by 20.28% and cutting force, thrust force and feed force by 9.94%, 17.38% and 7.25%, respectively. [ABSTRACT FROM AUTHOR]

Copper plays key catalytic and regulatory roles in biochemical processes essential for normal growth, development, and health. Defects in copper metabolism cause Menkes and Wilson's disease, myeloneuropathy, and cardiovascular disease and are associated with other pathophysiological states. Consequently, it is critical to understand the mechanisms by which organisms control the acquisition, distribution, and utilization of copper. The intestinal enterocyte is a key regulatory point for copper absorption into the body; however, the mechanisms by which intestinal cells transport copper to maintain organismal copper homeostasis are poorly understood. Here, we identify a mechanism by which organismal copper homeostasis is maintained by intestinal copper exporter trafficking that is coordinated with extraintestinal copper levels in Caenorhabditis elegans. Specifically, we show that CUA-1, the C. elegans homolog of ATP7A/B, localizes to lysosome-like organelles (gut granules) in the intestine under copper overload conditions for copper detoxification, whereas copper deficiency results in a redistribution of CUA-1 to basolateral membranes for copper efflux to peripheral tissues. Worms defective in gut granule biogenesis exhibit defects in copper sequestration and increased susceptibility to toxic copper levels. Interestingly, however, a splice isoform CUA-1.2 that lacks a portion of the N-terminal domain is targeted constitutively to the basolateral membrane irrespective of dietary copper concentration. Our studies establish that CUA-1 is a key intestinal copper exporter and that its trafficking is regulated to maintain systemic copper homeostasis. C. elegans could therefore be exploited as a whole-animal model system to study regulation of intra- and intercellular copper trafficking pathways. [ABSTRACT FROM AUTHOR]

In any metal cutting operation, the cutting fluid plays a vital role by cooling the surface of the work piece and the cutting tool, removing chips from the cutting zone and by lubricating the tool–work piece interface. However, misuse of the cutting fluid and wrong methods of its disposal can affect human health and the environment badly. Also, it accounts for 16–20% of the total cost of manufacturing in the production industry. Among various techniques available on application of the coolant, researchers, of late, have been focussing on Near Dry Machining (NDM)/Minimum Quantity Lubrication (MQL) as it minimizes the use of coolant by spraying the mixture of compressed air and cutting fluid in an optimized manner instead of flood cooling. The MQL technique has proved to be suitable because it complies with the requirements of ‘green’ machining. This paper presents a review of the important research papers published regarding the MQL-based application of mineral oils, vegetable oils and nanofluid-based cutting fluids for different machining processes, such as, drilling, turning, milling and grinding, etc. The paper explains the mechanism of the MQL technique. In a systematic manner, the present work also discusses its effect on the performance parameters of different machining processes. Most of the experimental studies have shown that application of MQL produces surface better than dry machining and similar to that as produced under wet machining. Its application also reduces cutting forces, cutting zone temperature, tool wear, friction coefficient in comparison to dry and wet machining. Therefore, MQL technique has proved to be a viable alternative to the flood lubrication under similar performance parameters. [ABSTRACT FROM AUTHOR]

A colloidal mixture of nanometre-sized (<100 nm) metallic and non-metallic particles in conventional fluid is called nanofluid. Nanofluids are considered to be potential heat transfer fluids because of their superior thermal and tribological properties. In recent period, nanofluids have been the focus of attention of the researchers. This paper presents a summary of a number of important research works that have been published on rheological behaviour of nanofluids. This review article not only discusses the influence of particle shape and shear rate range on rheological behaviour of nanofluids but also studies other factors affecting the rheological behaviour. These other factors include nanoparticle type, volumetric concentration in different base fluids, addition of surfactant and externally applied magnetic field. From the literature review, it has been found that particle shape, its concentration, shear rate range, surfactant and magnetic field significantly affect the rheological behaviour of any nanofluid. It has been observed that nanofluids containing spherical nanoparticles are more likely to exhibit Newtonian behaviour and those containing nanotubes show non-Newtonian flow behaviour. Furthermore, nanofluids show Newtonian behaviour at low shear rate values while behave as non-Newtonian fluid at high shear rate values. Authors have also identified the inadequacies in the research works so far which require further investigations. [ABSTRACT FROM AUTHOR]