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There is a critical limit of thrust force during drilling operation in a composite laminate below which no delamination takes place, which is known as the “critical thrust force”. In this paper, various critical thrust force models have been discussed in detail for circular- and elliptical-shaped delaminations around the drilled hole. Critical thrust force models for circular-shaped delamination for isotropic composite laminates and anisotropic composite laminates for different loadings like point load, uniformly distributed load, triangular load, and their combinations using different drill geometries have been discussed. With elliptical-shaped delamination, critical thrust force models for anisotropic composite laminates are discussed for: point load, uniformly distributed load, combined point plus distributed load, and point load for antisymmetric composite laminates. At several locations, graphs have been created to illustrate the dependence of various parameters on the critical thrust force. These graphs will be of use for practising engineers while selecting tool or/and machining parameters during drilling of polymer matrix composites. A tool designer can get good insight from these graphs while designing an optimal drilling tool. The paper highlights the importance of load distribution across the drill causing deflection leading to damage due to delamination in composite laminates. Special drill geometries help in better distribution of thrust forces towards periphery and improve the critical thrust force for the prevention of damage due to delamination during drilling in composite laminates.

Electrochemical micromachining (ECMM) is a well-known advanced machining process for fabrication of micro components such as tools, nozzles, mixers, etc. on electrically conductive workpieces. In the present work, experiments are conducted for fabrication of micro tools and micro patterns on the in-house developed and fabricated electrochemical micromachining setup. Effect of various process parameters such as voltage, interelectrode gap, machining time, duty cycle, and electrolyte concentration are studied on micro tools and over potential (in case of fabrication of micro patterns). It is observed that the average change in diameter of the micro tool after the ECMM process increases almost linearly with increase in voltage and time, and increases quadratically with increase in pulse duty ratio and electrolyte concentration. Overpotential increases with increase in applied voltage, interelectrode gap, and duty cycle. Further, overpotential initially decreases quadratically with increase in electrolyte concentration and then increases.

Introduction: Hypothyroidism in adults has an insidious onset with a range of non-specific symptoms resulting in delayed diagnosis. Hypothyroidism is characterized by a broad clinical spectrum ranging from an overt state of myxedema, end-organ effects and multisystem failure to an asymptomatic or subclinical condition with normal levels of thyroxine and triiodothyronine and mildly elevated levels of serum thyrotropin. Thyroid dysfunction leads to altered glucose and lipid metabolism leading to insulin resistance, which is an important risk factor for cardio vascular diseases. This study attempts to study clinical and biochemical profile of patients with subclinical hypothyroidism or overt hypothyroidism. Aim of study:To study clinical and investigative profile of hypothyroidism in the newly diagnosed patients of hypothyroidism.Methods: All newly diagnosed hypothyroidism patients fulfilling inclusion and exclusion criteria were taken in to study. Demographic profile of all enrolled patients was recorded. They were subjected to detailed history and examination and the findings were recorded as a predesigned Performa. The clinical diagnosis of hypothyroidism was made as per Indian thyroid society guidelines. The following laboratory investigations were performed: serum lipid profile and serum uric acid using enzymatic assay, fasting insulin, creatinine, direct bilirubin, and the following liver function parameters: aspartate aminotransferase (AST), alanine aminotransferase (ALT). Thyroid-hormone profile, including thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), and free thyroxine (FT4), including anti-thyroid peroxidase (TPO). Observation and results:Between October 1, 2015 and September 30, 2016, 226 patients with newly diagnosed hypothyroidism were studied. Out of 226 patients, 48 patients excluded from the study. Central hypothyroidism was present in 4 patients and 44 were pregnant and lactating women. 178 patients with newly diagnosed hypothyroidism were enrolled in study. Out of 178 patients' subclinical hypothyroidism was present in 29(16.9%) patients. Out of 178 patients, 131 (73.6%) were females and 47 (26.4%) were males and various parameters were studied. Conclusion:Our study confirms that dyslipidemia, insulin resistance and metabolic syndrome correlate positively with newly diagnosed hypothyroid patients.

Objective:Fetal microchimerism during pregnancy and abortion has been linked with autoimmune hypothyroidism in females. We conducted a case–control study to investigate the odds of “abortion in the past” in the newly diagnosed hypothyroid females compared to their age-matched euthyroid controls.Methods:All consecutive newly diagnosed hypothyroid females, over 1 year, were enrolled as cases. Age-matched euthyroid controls were selected from the same region. The exposure variable tested was “past history of abortion (elective or therapeutic).”Results:Totally, 120 cases and 172 controls were recruited over 1 year with a mean age of 42.2 ± 9.8 years and 41.1 ± 12.4 years, respectively. The exposure variable (abortion) was present in 71 (59%) cases and 10 (6%) controls. Odds ratio (OR): 23.5 (12.2–48.9) P < 0.0001. Autoimmunity, based on thyroid peroxidase (TPO) positivity (TPO levels ≥30 U/ml), was present in 92 (77%) of the cases; TPO was negative in 28 (33%) of cases. The exposure variable was documented in 62.4% and 50% of TPO positive and negative cases, respectively (P = 0.28).Discussion and Conclusion:The study suggests that abortion (elective or therapeutic) in the past is strongly associated with newly diagnosed hypothyroidism in females aged 42.2 ± 9.8 years; OR: 23.5 (P < 0.0001). Interestingly, abortion was associated with both, TPO positive and negative hypothyroidism.