Microwave-assisted synthesis, characterization and tribological properties of a g-C3N4/MoS2 nanocomposite for low friction coatings

This study explores the tribological performance of microwave-assisted synthesized g-C3N4/MoS2 coatings. The two-dimensional transition metal dichalcogenide (TMD) nanosheet is getting prominence in the study of tribology due to its layered structure. The graphitic carbon nitride (g-C3N4) nanosheet was made using the calcination method and its nanocomposite with molybdenum disulfide (MoS2) was produced using a microwave-assisted method. The structure and morphology of the samples were characterized by some well-known methods, and tribological properties were studied by a pin-on-disc (POD) apparatus. Morphological analysis revealed that graphitic carbon nitride and molybdenum disulfide coexisted, and the layer structured MoS2 was well dispersed on graphitic carbon nitride nanosheets. BET analysis was used to determine the pore volume and specific surface area of the synthesized materials. The inclusion of MoS2 nanoparticles caused the composite's pore volume and specific surface area to decrease. The reduction in g-C3N4 pore volume and specific surface area confirmed that the pores of calcinated graphitic carbon nitride were filled with MoS2 nanoparticles. The tribological property of g-C3N4/MoS2 nanocomposite was systematically investigated under different factors such as applied loads (5N to 15N), sliding speed (500 to 1000 mm/s) and material composition (uncoated, MoS2-coated, 9 wt.% of g-C3N4 and 20 wt.% of g-C3N4 in the composite). The optimal composite material ratio was taken 9%, by weight of g-C3N4 in the g-C3N4/MoS2 composite for a variety of levels of loads and sliding speeds. The results indicates that the incorporation of g-C3N4 in nanocomposites could reduce friction and improve wear life, which were better than the results with single MoS2. This study demonstrates a solution to broaden the possible uses of g-C3N4 and MoS2-based materials in the field of tribology.Web of Science1212art. no. 184

Spin distribution as a probe to investigate the dynamical effects in fusion reactions

The spin distributions are measured for the compound nucleus 80Sr populated in the reactions 16O+64Zn and 32S+48Ti. The comparison of the experimental results for both the systems shows that the mean γ-ray multiplicity values for the system 32S+48Ti are lower than those for 16O+64Zn. The spin distribution of the compound nucleus populated through the symmetric channel is also found to be lower than the asymmetric channel. Present investigation directly shows the effect of entrance channel mass asymmetry on the reaction dynamics

Is every chest pain a cardiac event?: an audit of patients with chest pain presenting to emergency services in India

Chest pain is one of the most common presenting complaints of a cardiac ischemic event. As the presenting complaint often dictates further interventions, it is necessary to identify and stratify the risk of a cardiac ischemic event in cases of chest pain as the primary complaint. The study also aimed to evaluate the actual number of cardiac ischemic events from all cases of complaints of chest pain. The study aimed to evaluate the occurrence of chest pain as an emergency attended by our emergency management service-108 services. During the period of January 1st-December 31st 2007, a total of 9,130 calls with chest pain were attended to, out of which 6,235 (68.3%) were included who were patients above 30 years of age and for whom complete data were available. Risk factor analysis to predict myocardial events and stratification was done to calculate an odds ratio. A cardiac risk scoring was devised and analyzed for probability of survival against final outcome. Probable cardiac cases were 5,887, out of which the critical/mortal cases were chosen for risk factor analysis and stratification. This resulted in age (odds ratio: 1.6; 95% CI: 1.3-2.0) and respiratory rate (odds ratio: 1.4; 95% CI: 1.1-1.8) being significant risk factors. The cardiac risk scoring accurately predicted 71% of final outcome. Age and respiratory rate may be constituted as primary qualifying criteria to define a cardiac ischemic event and given higher weights in risk scoring. Systolic blood pressure, which showed a non-significant change, may also be included to accurately identify cardiac ischemic events. From the total sample of patients presenting with chest pain, only 5.5-8% were definitive cardiac ischemic events

Attempted suicides in India: a comprehensive look

Suicide continues to be one of the biggest killers in the world, with suicide rates varying between 8.1 and 58.3/100,000 population for different parts of India. Andhra Pradesh, the fourth largest state in India, is responsible for more than 11% of these. Unfortunately, most suicides are under-reported and there is scant data on attempted suicides. This study aimed to comprehensively study the characteristics of attempted suicides in Andhra Pradesh and using the primary data, make secondary projections for the forthcoming years. Using Patient Care Record (PCR) forms of all emergencies serviced by 108, the first comprehensive emergency service in India, an analysis of all cases was done to detect possible suicides during the period January-December 2007. A follow up 48 hours later was then done to confirm status and diagnosis. A total of 1007 cases were recorded as confirmed suicides. Hanging and insecticide poisoning (72%) were the most common methods used. Males preferred hanging and insecticide poisoning while females preferred self-immolation and hanging as common methods. Self-immolation and insecticide poisoning had the highest mortality (41.6%). Estimates of attempted suicides for the year 2008 revealed a mean of 3.2-3.8 per 1000 population for males, 3.3-3.7 per 1000 population for females and 6.4-7.6 per 1000 population combined. A serious epidemic of suicides seems to be in store in the coming years unless preventive steps in the form of policy changes are undertaken. Restricting access to poisonous substances or prescription drugs and taking into consideration the prevailing social, economic and cultural factors could help in reducing numbers. Starting tele-help services or offering brief interventions during hospital stays are other programs which may be considered

An Investigation for Minimizing the Wear Loss of Microwave-Assisted Synthesized g-C₃N₄/MoS₂ Nanocomposite Coated Substrate

Mechanical components frequently come into contact against one another causing friction that produces heat at the contact area and wear of the components that shortens part life and increases energy consumption. In the current study, an attempt was made to optimize the parameters for the pin-on-disc wear tester. The experiments were carried out in ambient thermal conditions with varying sliding speeds (0.5 m/s, 0.75 m/s, and 1.0 m/s) and applied loads (5 N, 10 N, and 15 N) for pure molybdenum disulfide with 9% and 20% weight percentage of graphitic carbon nitride (g-C3N4) in molybdenum-disulfide (MoS2)-nanocomposite-coated steel substrate. Analysis of variance (ANOVA) was used to determine the outcome of interaction between various constraints. To identify the minimum wearing conditions, the objective was defined as the criterion ‘smaller is better’. The maximum impact of the applied load on the coefficient of friction and wear depth was estimated to be 59.6% and 41.4%, respectively, followed by sliding speed. The optimal condition for the minimum coefficient of friction and wear was determined to be 15 N for applied load, 0.75 m/s for sliding speed, and weight percentage of 9 for g-C3N4 in MoS2 nanocomposite. At the 95% confidence level, applied load was assessed to have the most significant effect on the coefficient of friction, followed by sliding speed and material composition, whereas material composition considerably impacts wear, followed by loading and sliding speed. These parameters show the effect of mutual interactions. Results from the Taguchi method and response surface methodology are in good agreement with the experimental results

Evaluation of platelet surface glycoproteins in patients with Glanzmann thrombasthenia: Association with bleeding symptoms

Background & objectives: Glanzmann thrombasthenia (GT) is a rare, inherited autosomal recessive disorder characterized by qualitative or quantitative deficiency of integrin αIIbβ3 [glycoprotein IIb (GPIIb)/IIIa, CD41/CD61] diagnosed by absent or reduced platelet aggregation to physiological agonists, namely, collagen, adenosine-di-phosphate, epinephrine and arachidonic acid. The objective of this study was to quantitate platelet surface GPs, classify GT patients and relate the results with the severity of bleeding and platelet aggregation studies. Methods: Fifty one patients of GT diagnosed by platelet aggregation studies were evaluated for the expression of CD41, CD61, CD42a and CD42b on platelet surface by flow cytometry. The association between the clinical phenotype based on bleeding score and GT subtype on flow cytometric evaluation was assessed. Results: Twenty four (47%) patients of GT were classified as type I (as CD41/CD61 were virtually absent, <5%), six (11.8%) patients as type II (5-20% CD41/CD61) and 21 (41.2%) as type III or GT variants as they had near normal levels of CD41 and CD61. Type III GT patients had significantly lower numbers of severe bleeders (P=0.034), but the severity of bleeding did not vary significantly in type I and II GT patients. In all GT patients, mean CD41 expression was found to be lower than mean CD61 expression (P=0.002). Interpretation & conclusions: Type I GT was found most common in our patients and with lowered mean CD41 expression in comparison with CD61. Type III GT patients had significantly lower numbers of severe bleeders, but the severity of bleeding did not vary significantly in type I and II GT patients