Three-dimensional Bi-chalcogenide topological insulators exhibit surface states populated by massless Dirac fermions that are topologically protected from disorder scattering. Here, we demonstrate ...that these states can be enhanced or destroyed by strain in the vicinity of grain boundaries on the surface of epitaxial Bi2 Se3 (0001) thin films. Using scanning tunnelling and transmission electron microscopy, we show that the low-angle tilt grain boundaries in Bi2 Se3 (0001) films consist of arrays of alternating edge dislocation pairs. Along the boundary, these dislocations introduce periodic in-plane compressive and tensile strains. From tunnelling spectroscopy experiments and first-principles calculations, we find that whereas the energy of the Dirac state shifts in regions under tensile strain, a gap opens in regions under compressive strain, indicative of the destruction of the Dirac states at the surface. These results demonstrate that Dirac states can be tuned by strain at the atomic scale.
•Performance of an ice plant is investigated with nano-refrigerant (R134a/MWCNTs).•Effect of varied mass of MWCNTs (0.05 g-0.25 g) and R134a (175 g-225 g) is studied.•Pull-down time and power ...consumption are reduced by 17.9%, 21.46%.•COP and cooling capacity improved by 40.09% and 11.29% respectively.•Economic analysis is also carried out, the operational cost is reduced by 7.12%.
Ice plant is used for producing ice at a large scale from water filled in standard cans placed inside rectangular tanks filled with brine solution. Ice plant works on the vapour compression refrigeration (VCR) cycle, the researchers are focusing on minimizing compressor work and improving the cycle's performance by introducing nanoparticles with higher thermophysical properties. In this experimental investigation, the performance analysis of the test rig of an ice plant using varied masses of 0.05 g, 0.10 g, 0.15 g, 0.20 g, and 0.25 g of multi-walled carbon nanotubes (MWCNTs), dispersed in 250 ml polyolester (POE) oil charged with masses 175 g, 200 g, and 225 g of tetrafluoro ethane (R134a) refrigerants is carried out separately. REFPROP 9.1 software is used to obtain the properties of refrigerants. The evaluated parameters are pull-down time, cooling capacity, coefficient of performance (COP), Compressor work input, economic analysis, pressure ratio, thermal conductivity, absolute viscosity, and density. It is observed that in comparison to the pure refrigerant, the refrigerator's pull-down time and compressor work are reduced by 17.9% and 21.46%, whereas, COP and cooling capacity improved by 40.09% and 11.29% for 225 g mass of R134a with 250 ml POE respectively. In addition, thermal conductivity, density, and absolute viscosity improved at both the suction side and discharge side of the compressor.
Caesalpinia sappan L.(CS) is a plant of Leguminosae family,commonly known as Brazil or Sappan wood.CS is distributed in Southeast Asia and its dried heartwood has been used as traditional ingredient ...of food or beverages and has a wide variety of medicinal properties.Higher extraction yield of CS wood was achieved with 95% ethanol for 2 h.Chemical constituent’s investigation of sappan wood resulled in the isolation of various structural types of phenolic components including one xanihone,one coumarin,three chalcones,two flavones three homoisoflavonoids and brazilin.Brazilin(6a S-cis)-7,11b-dihydrobcnzbindeno1.2-dpyran-3.6a.9.10(6H)- tetroll.a major and active compound found in CS heartwood.Most of the folkloric uses of brazilin were validated by the scientific studies such as antioxidant,antibacterial,anti-inflammatory,anti-photoaging.hypoglycemic,vasorelaxant,hepatoproteetive and anti-acne activity.CS heartwood extract is safe and did not produce any acute or subacute toxicity in both male and female rats.Brazilin is the safe natural compound having potential to develop as a medicinal compound with application in food,beverage,cosmetics and pharmaceutical industries to screen its clinical use in modern medicine.The information gained could provide the important and potential approach for pharmaceutical researcher to implicate the knowledge of brazilin in the formulation of new drug and to reveal therapeutic and gaps requiring future research opportunities.More studies are needed to evaluate the potential application of brazilin as preservative and coloring agent in food processing industries.
Therapeutic hypothermia (TH) benefits survivors of cardiac arrest and neonatal hypoxic–ischemic injury and may benefit stroke patients. Large TH clinical trials, however, have shown mixed results. ...Given the substantial pre-clinical literature supporting TH, we explored possible mechanisms for clinical trial variability. Using a standard rodent stroke model (n = 20 per group), we found smaller infarctions after 2 h pre- or post-reperfusion TH compared to 4 h. To explore the mechanism of this discrepancy, we used primary cell cultures of rodent neurons, astrocytes, or endothelial cells subjected to oxygen–glucose deprivation (OGD). Then, cells were randomly assigned to 33℃, 35℃ or 37℃ for varying durations after varying delay times. Both 33 and 35℃ TH effectively preserved all cell types, although 33℃ was superior. Longer cooling durations overcame moderate delays to cooling initiation. In contrast, TH interfered with astrocyte paracrine protection of neurons in a temperature-dependent manner. These findings suggest that longer TH is needed to overcome delays to TH onset, but shorter TH durations may be superior to longer, perhaps due to suppression of astrocytic paracrine support of neurons during injury. We propose a scheme for optimizing TH after cerebral injury to stimulate further studies of cardiac arrest and stroke.
•An evaporative vapour compression based combined air conditioning system was fabricated and tested.•System was run in three different modes according to the climatic conditions.•System performance ...was studied for wide range of ambient conditions.•Effects of various operating parameters on system performance were studied in detail.•Maximum energy saving was found 24% at 43.2°C and 18.1% relative humidity.
An evaporative–vapour compression based combined air conditioning system for providing required human comfort conditions at comparatively low cost has been presented. The combined system has been experimentally analysed in a particular experimental setup at Bhopal, India for a wide range of ambient conditions in different modes of operation according to the climatic condition. System has also compared from conventional vapour compression air conditioner working at same fresh air ratio (FAR) and air flow rate for similar inside set temperature. Maximum energy saving in the combined system was found 23.8% at 43.3°C ambient temperature and 18.1% relative humidity, while it was run at no profit–no loss condition for humid climate. The system is working well with an average monthly power saving of 58.5kWh for moderate hot and dry, and 163.5kWh for hot and dry conditions. Therefore it could be a better alternative to conventional air conditioning system for dry and humid climate with a payback period of 8.1years.
To realize the commercialization of sustainable materials, new polymers must be generated and systematically evaluated for material characteristics and end-of-life treatment. Polyester polyols made ...from renewable monomers have found limited adoption in thermoplastic polyurethane (TPU) applications, and their broad adoption in manufacturing may be possible with a more detailed understanding of their structure and properties. To this end, we prepared a series of bio-based crystalline and amorphous polyester polyols utilizing azelaic acid and varying branched or non-branched diols. The prepared polyols showed viscosities in the range of 504–781 cP at 70 °C, with resulting TPUs that displayed excellent thermal and mechanical properties. TPUs prepared from crystalline azelate polyester polyol exhibited excellent mechanical properties compared to TPUs prepared from amorphous polyols. These were used to demonstrate prototype products, such as watch bands and cup-shaped forms. Importantly, the prepared TPUs had up to 85% bio-carbon content. Studies such as these will be important for the development of renewable materials that display mechanical properties suitable for commercially viable, sustainable products.
Abstract
Molybdenum disulfide (MoS
2
) has been combined so far with other photodetecting semiconductors as an enhancing agent owing to its optical and electronic properties. Existing approaches ...demonstrated MoS
2
-incorporated photodetector devices using complex and costly fabrication processes. Here, we report on simplified one-step on the chemical vapor deposition (CVD) based synthesis of a unique microfiber/microflower MoS
2
-based heterostructure formed by capturing MoO
2
intermediate material during the CVD process. This particular morphology engenders a material chemical and electronic interplay exalting the heterostructure absorption up to ~ 98% over a large spectral range between 200 and 1500 nm. An arsenal of characterization methods were used to elucidate the properties of these novel heterostructures including Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectrometry, high-resolution transmission and scanning electron microscopies, and Kelvin probe force microscopy. Our findings revealed that the MoS
2
and the MoO
2
crystallize in the hexagonal and monoclinic lattices, respectively. The integration of the MoS
2
/MoO
2
heterostructures into functional photodetectors revealed a strong photoresponse under both standard sun illumination AM1.5G and blue light excitation at 450 nm. Responsivity and detectivity values as high as 0.75 mA W
−1
and 1.45 × 10
7
Jones, respectively, were obtained with the lowest light intensity of 20 mW cm
−2
at only 1 V bias. These results demonstrate the high performances achieved by the unique MoS
2
/MoO
2
heterostructure for broadband light harvesting and pave the way for their adoption in photodetection applications.
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