Long Period Gratings (LPGs) have been developed using carbon dioxide laser in a standard optical fibre. LPGs with a periodicity of 600 μm and grating length of 24 mm have been inscribed on standard single mode fibre. Such gratings have been used in designing temperature sensors and temperature is monitored up to 80 • C. The sensitivity of such type of sensor is 0·06 nm/ • C where as for standard Fibre Bragg Grating (FBG) it is 0·011 nm/ • C. The LPG performance is also evaluated after γ -ray irradiation for total dose of 5 KGy and has not shown any effect on transmission spectrum.

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Background. Increased mobile phone usage among undergraduate medical students causes a detrimental effect on their health. The main focus of this study is to determine the pattern of mobile phone usage among undergraduate medical students in Hyderabad, India, and the detrimental effect on their health due to excess mobile use. Materials and Methods. A cross-sectional study was conducted among undergraduate medical students from various medical colleges in Hyderabad, India, from September 2020 to January 2021. Data were collected from 626 respondents using a semistructured, pretested questionnaire. Smartphone Addiction Scale-Short Version (SAS-SV) was used to assess the risk of smartphone addiction. Microsoft Excel and SAS were employed to analyze the data. Associations were examined using Fisher’s exact test. Results. 100% of the respondents were using mobiles, with 83.2% spending more than 4 hours on them. Only 22% reported that no mobile use during classes. Half (51.6%) admitted to keeping their mobiles close by while sleeping. 84.3% used social networking apps via their mobiles. Common symptoms arising from prolonged mobile usage included eye strain (67.9%), blurred vision (31.4%), and numbness or tingling in palms (30.9%). 52.70% of the respondents were at high risk of mobile addiction according to SAS-SV. Screen time more than 4 hours was associated with high risk of mobile addiction ( p < 0.0001 ). Significant association was found between high risk of mobile addiction and eye strain ( p < 0.0001 ), blurry vision ( p = 0.0115 ), numbness/tingling in palms ( p < 0.0001 ), and heat/tingling in the auditory area ( p < 0.0001 ). Conclusion. The study shows the alarming rate of risk of smartphone addiction among medical students. Students can be encouraged to assess their mobile addiction status and become aware of the issue. More research may be performed to develop standardized tools for early identification of mobile addiction and appropriate therapies for its rectification.

Purpose The purpose of this study is to investigate the microstructural evolution of high-strength 2024 Al alloy prepared by the laser powder bed fusion (L-PBF) additive manufacturing (AM) route. The high-strength wrought Al alloy has typically been unsuitable for AM due to its particular solidification characteristics such as hot cracking, porosity and columnar grain growth. Design/methodology/approach In this research work, samples were fabricated using L-PBF under various laser energy densities by varying laser power and scan speed. The microstructural features that developed during the solidification are correlated with operating laser parameters. In addition, finite element modelling (FEM) was performed to understand the experimentally observed results. Findings Microstructure evolution and defect formation have been assessed, quantified and correlated with operating laser parameters. Thermal behaviour of samples was predicted using FEM to support experimental observations. An optimised combination of intermediate laser power and scan speed produced the least defects. Higher energy density increased hot tearing along the columnar grain boundaries, while lower energy density promoted void formation. From the quantitative results, it is evident that with increasing energy density, both the top surface and side wall roughness initially reduced till a minimum and then increased. Hardness and compressive strength were found to decrease with increasing power density due to stress relaxation from hot tearing. Originality/value This research work examined how L-PBF processing conditions influence the microstructure, defects, surface roughness and mechanical properties. The results indicates that complete elimination of solidification cracks can be only achieved by combining process optimisation and possible grain refining strategies.

This information may improve prevention counseling and aid preparation for the management of pediatric HNT.