Sensitivity and Spatial Resolution for Thermal Conductivity Measurements using Non-contact Scanning Thermal Microscopy with Thermoresistive Probes under Ambient Conditions

Thermoresistive probes are increasingly popular in thermal conductivity characterization using Scanning Thermal Microscopy (SThM). A systematic analysis of the thermal conductivity measurement performance (sensitivity and spatial resolution) of thermoresistive SThM probe configurations that are available commercially is of interest to practitioners. In this work, the authors developed and validated 3-Dimensional Finite Element Models (3DFEM) of non-contact SThM with self-heated thermoresistive probes under ambient conditions with the probe-sample heat transfer in transition heat conduction regime for the four types of SThM probe configurations resembling commercially available products: Wollaston wire (WW) type probe, Kelvin Nanotechnology (KNT) type probe, Doped Silicon (DS) type probe, and Nanowire (NW) type probe. These models were then used to investigate the sensitivity and spatial resolution of the WW, KNT, DS and NW type probes for thermal conductivity measurements in non-contact mode in ambient conditions. The comparison of the SThM probes performance for measuring sample thermal conductivity and for the specific operating conditions investigated here show that the NW type probe has the best spatial resolution while the DS type probe has the best thermal conductivity measurement sensitivity in the range between 2-10 W·m−1·K−1. The spatial resolution is negatively affected by large probe diameters or by the presence of the cantilever in close proximity to the sample surface which strongly affects the probe-sample heat transfer in ambient conditions. An example of probe geometry configuration optimization was illustrated for the WW probe by investigating the effect of probe wire diameter on the thermal conductivity measurement sensitivity, showing ∼20% improvement in spatial resolution at the diameter with maximum thermal conductivity measurement sensitivity.

Preparation of Coronavirus nosodes sourced from a clinical sample of SARS-Cov-2 positive patient, inactivated strain, and spike glycoprotein

Introduction Nosodes, the homeopathic preparations sourced from biological materials including clinical samples, cultures of organisms, and diseased tissues have been in use against the source-specific infections as well as other diseases. The nosodes have demonstrated some efficacy in managing epidemics, such as influenza, dengue, and leptospirosis. This article presents the need and process of development of nosodes from the SARS-CoV-2 to explore its prophylactic and therapeutic potentials against certain related viral diseases. MATERIALS AND METHODS A clinical sample of SARS-Cov-2 positive patient, based on the cycle threshold (CT) value of the qRT-PCR, heat-inactivated SARS-CoV-2, and spike glycoprotein all were processed for making nosodes as per the method described in Homoeopathy Pharmacopoeia of India. Molecular tests, such as qRT- PCR and sterility tests were performed to establish the live organisms, RNA material, and the absence of contamination. RESULT Three variants of Coronavirus Nosode were developed using a clinical sample, heat-inactivated SARS-CoV-2, and spike glycoprotein. In potencies 3c and above, no detectable SARS-CoV-2 RNA material was found by PCR. The analytical results for nosodes were reported as compliant for sterility testing as per the IP. CONCLUSION Three variants of Coronavirus nosodes were prepared which need to be evaluated further through pre-clinical and clinical studies.

SARS-CoV-2 detection by extraction-free qRT-PCR for massive and rapid COVID-19 diagnosis during a pandemic

COVID-19 pandemic severely impacted the healthcare and economy on a global scale. It is widely recognized that mass testing is an efficient way to contain the infection spread as well as the development of informed policies for disease management. However, the current COVID-19 worldwide infection rates increased demand in the rapid and reliable screening of SARS-CoV-2 infection. We compared the performance of qRT-PCR in direct heat-inactivated, heat-inactivated/pelleted samples against RNA in a group of 74 subjects (44 positive and 30 negative). In addition, we compared the sensitivity of heat-inactivated/pelleted in another group of 196 COVID-19 positive samples. Our study suggests that swab sample heat-inactivation and pelleting show higher accuracy for SARS-CoV-2 detection PCR assay compared to heat-inactivation only (89% vs 83% of the detection in RNA). The accuracy of detection using direct samples varied depending on the sample transport and storage media as well as the viral titer. Our study suggests that purified RNA provides more accurate results, however, direct qRT-PCR may help to significantly increase testing capacity. Switching to the direct sample testing is justified if the number of tests is doubled at least.

Wear Behavior of Plasma Processed LM6 Alloy

In the current work, wear behavior of plasma processed LM6 alloy is investigated. LM6 alloy was prepared by plasma technique. The samples were aged at 350°C & 450°C for 2 hours followed by water quenching. A comparative study of the metallographic structure and properties viz. hardness, density and wear of the non-heat and heat treated alloy samples were carried out. A very fine lamellar structure is observed in case of 450°C heat treated samples than that of sample heat treated at 350°C and non-heat treated samples. Highest hardness value of 68.11 VHN is observed with the sample heat treated at 450°C. Density is found to be the lowest in non-heat treated samples and it increases with increasing heat treatment temperature. Wear experiments were carried on a pin-on-disc set up (of Ducom make), varying applied loads (between 10-40Newton and varying sliding speed (from 0.94 m. s-1 to 2. 83m.s-1). Maximum wear resistance is observed with the specimen heat treated at 450°C.

HEAT TREATMENT EFFECT ON THE CREEP OF INDUSTRIAL COPPER WIRE

<p class="Default">Creep behavior of copper wire, produced by wiredrawing process in ENICAB Biskra, has been investigated by creep tests at 340°C under the stress 98,108 and 118 MPa. In this investigation, three samples have been tested: copper drawn wire non heat treated, and heat treated at 600°C and 700°C. Microstructure after the creep test was observed by optical microscopy to understand the rupture mechanism. We have found that the sample heat treated at 600 °C had a longer creep life. We have also deduced that the dislocation creep was the creep deformation mechanism of the drawn copper. SEM observations of fractured surfaces after creep tests of drawn copper wire non heat treated and treated 10 min at 600 ° C under stress of 118 MPa.</p>

Effect of Heat Treatment on the Micro-Structural, Crystallinity and Photocatalytic Properties of Hydrothermally Prepared Titanate Nanowires

Titanate nanowires were synthesised by hydrothermal process in 10M NaOH aqueous solution at 200oC for 24h. The samples were washed repeatedly in HCl aq. solution and deionized water until pH ~7. Subsequently, the samples were heat-treated at 400-850°C in air for 2h. The X-ray diffraction (XRD) analysis of the sample heat-treated at 800°C showed the crystalline structure of sodium titanate (Na2Ti6O13 ), while the presence of anatase phase was detected from the sample heat-treated at 850°C. Wire-like morphology of the synthesized sample was observed using FE-SEM. The photocatalytic activity of the samples heat-treated at 600,800, 850°C and 900°C was investigated by measuring the degradation of methylene blue (MB) in aqueous solution under UV-light irradiation and more than 90% of the dye was efficiently degraded by the sample heat-treated at 850°C within 45 minutes irradiation time as compared to other tested samples.

Synthesis of porous sulfonated carbon as a potential adsorbent for phenol wastewater

The work reports a facile synthesis procedure for preparation of porous sulfonated carbons and its suitability for adsorption of phenol. The sulfonated carbon was synthesized utilizing a simplified, single-step, shorter duration process by sulfonation, dehydration and carbonization of sucrose in sulfuric acid and tetraethylorthosilicate. The surface and internal structures of the adsorbents were characterized utilizing various characterization techniques to understand the porous nature and surface functional groups of the porous matrix. Adsorption capacity was found to be highest for the sample heat treated at 600 °C, with the maximum adsorption capacity of 440 mg/g at 30 °C. The adsorption isotherms were tested with the Freundlich and Langmuir adsorption isotherms models to identify the appropriate adsorption mechanism.