Asymptotic analysis and reflection photoelasticity for the study of transient crack propagation in graded materials

The behavior of a rapidly moving transient crack in functionally graded materials (FGMs) is investigated theoretically and experimentally. First, a systematic theoretical analysis is presented for the development of the transient elastodynamic local stress, strain, and displacement field expansions near a growing mixed mode crack tip in FGMs. The crack propagation direction is assumed to be inclined to the direction of the property variation. The displacement potential approach in conjunction with asymptotic analysis is utilized to derive explicit expressions for stress, strain, and in-plane displacement fields. The transient crack growth is assumed to include processes in which both the crack tip speed and the dynamic stress intensity factor are differentiable functions of time. These stress fields are used to generate the contours of constant maximum shear stress (isochromatics fringes) and the effect of transient crack growth on these contours is discussed. To further understand the transient crack growth behavior, a series of dynamic fracture experiments are performed with functionally graded material fabricated in-house. The phenomenon of transition from a static crack to a dynamic mode I crack is examined in these experiments. The full-field stress data around the crack is recorded using dynamic photoelasticity and high-speed digital photography. Due to opaqueness of FGMs, birefringent coatings are employed to obtain the full-field isochromatics around the crack tip. The stress field expansions developed in the first part of the study are used to interpret the experimental observations. The results of the experiments showed that the higher order transient expansion provides an accurate representation of crack tip fields under severe transient conditions

Pregnancy in unicornuate uterus without rudimentary horn: a case report

A unicornuate uterus is associated with numerous obstetric and gynaecological complications such as infertility, endometriosis, miscarriage, malpresentations, and intrauterine growth restriction. Around 2.3-13% of Mullerian duct anomalies present as unicornuate uterus. Management of unicornuate uterus is still uncertain and it leads to poorer pregnancy outcome. We present here a case of 26-year-old primigravida who presented to us with 40-weeks pregnancy associated with breech presentation. She was taken for elective caesarean section and intra-operatively she was found to have unicornuate uterus without rudimentary horn. Unicornuate uterus is associated with poor pregnancy outcome but a successful pregnancy is possible. Usual presentation of patients with unicornuate uterus is near their menarche and they have higher than usual gynaecological complications. Pregnancies in unicornuate uterus are prone to intra uterine growth restriction hence serial ultrasound should be done for regular fetal growth monitoring

Proximity-induced superconductivity in nanowires: Mini-gap state and differential magnetoresistance oscillations

We study proximity-induced superconductivity in gold nanowires as a function of the length of the nanowire, magnetic field, and excitation current. Short nanowires exhibit a sharp superconducting transition, whereas long nanowires show nonzero resistance. At intermediate lengths, however, we observe two sharp transitions; the normal and superconducting regions are separated by what we call the mini-gap phase. Additionally, we detect periodic oscillations in the differential magnetoresistance. We provide a theoretical model for the mini-gap phase as well as the periodic oscillations in terms of the coexistence of proximity-induced superconductivity with a normal region near the center of the wire, created either by temperature or application of a magnetic field.Comment: 11 pages, 4 figure

Novel 2,5-disubstituted-1,3,4-oxadiazole derivatives induce apoptosis in HepG2 cells through p53 mediated intrinsic pathway

AbstractA series of novel 1,3,4-oxadiazole derivatives (OSD, OCOD, ONOD, OPD, COD, PMOD, and PCOD) were synthesized and characterized. Their structures were confirmed on the basis of IR, NMR and mass spectroscopy and molecular weights were found in the range 300–325g/mol. Cancerous cell lines (MCF-7, HepG2) and non-cancerous cell lines (Chang liver cells) were treated with these compounds for 48h, which caused dose dependent decrease in the cell viability. From the seven derivatives, OSD was found to be most potent with IC50 value close to 50μM on all tested cell lines. Hence, this compound was selected for mechanistic study on HepG2 cell lines. Fluorescent cell staining and DNA fragmentation study of 50μM OSD on HepG2 cells, showed events marked by apoptosis such as nuclear fragmentation, cytoplasm shrinkage and DNA damage. Further, the cells with same treatment were quantified for apoptosis using annexin V-PI flow cytometric technique. The percentage of apoptotic cells was significantly higher (p<0.05) after OSD treatment compared to control cells. OSD induced a significant increase (p<0.05) in the expression of the tumor suppressor p53 in HepG2 cells. The constitutive expression of anti-apoptotic protein Bcl-2 significantly decreased (p<0.05) after treatment, while the expression of proapoptotic protein Bax significantly increased (p<0.05). The change in Bax to Bcl-2 ratio suggested involvement of Bcl-2 family in induction of apoptosis. Furthermore, the levels of caspase-9 and caspase-3 were significantly (p<0.05) up regulated in HepG2 cells after OSD treatment. The data suggest that 1,3,4-oxadiazole derivatives induce apoptosis mediated by intrinsic pathway of apoptosis. The findings strengthen the potential of the 1,3,4-oxadiazole scaffold OSD, as an agent with chemotherapeutic and cytostatic activity in human hepatocellular carcinoma in vitro

Emerging and re-emerging viral infections in India

The number of outbreaks have &nbsp;progressively increased since many years in India. In this era of globalization and rapid international travel, any infectious disease in one country can become a potential threat to the entire globe. Outbreaks of Nipah, Zika, Crimean- Congo Haemorrhagic Fever and Kyasanur Forest Disease and have been reported since a decade and now we are facing COVID 19 pandemic. One of the challenges in the prevention of these outbreaks is that as the cases decrease, the felt need declines, the public demand decreases and the mitigation responses get overshadowed by the need of emergency responses elsewhere. The One Health approach is a movement to promote alliance between medicine field, veterinary medicine and environmental sciences to upgrade the health of humans, animals, and ecosystem. The data in this article is compiled from different websites and publications of World Health Organization (WHO), Centre for Disease Control and Prevention (CDC), Integrated Disease Surveillance Programme (IDSP), grey literature and media. There is an urgent need for better surveillance and disease burden assessments in the country and to gain detailed insights into vector biology, factors of environment influencing the diseases, mapping of endemic areas, strengthen intersectoral coordination, infection control practices, and ensure use of Personal Protective Equipment’s (PPE) and availability of drugs and vaccines to handle the outbreaks in a better way

COVID-19 Infection and Guillain-Barre Syndrome: A Case Series

The coronavirus disease 2019 (COVID-19) pandemic brought about an unprecedented time. Multiple systemic complications have been recognized with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as it can do much more than affect the respiratory system. One of the intriguing neurological complications is Guillain-Barre syndrome (GBS). We reviewed three cases in which patients presented with GBS following COVID-19 infection. All three cases had positive lumbar puncture results with albumino-cytological dissociation. Each patient was treated with plasmapheresis and improved clinically. Although an exact causal relationship between COVID-19 and GBS cannot be drawn from this case series alone, it signifies the importance of this complication. It warrants further studies to establish the causal relationship. One should have a high suspicion for acute inflammatory demyelinating polyneuropathy (AIDP) in patients presenting with acute onset of ascending weakness following COVID-19 infection

Effect of Fibrinolytic Therapy on ST-Elevation Myocardial Infarction Clinical Outcomes during the COVID-19 Pandemic: A Systematic Review and Meta-Analysis

BACKGROUND: ST-elevation myocardial infarction (STEMI) is the result of transmural ischemia of the myocardium and is associated with a high mortality rate. Primary percutaneous coronary intervention (PPCI) is the recommended first-line treatment strategy for patients with STEMI. The timely delivery of PPCI became extremely challenging for STEMI patients during the coronavirus disease 2019 (COVID-19) pandemic, leading to a projected steep rise in mortality. These delays were overcome by the shift from first-line therapy and the development of modern fibrinolytic-based reperfusion. It is unclear whether fibrinolytic-based reperfusion therapy is effective in improving STEMI endpoints. AIM: To determine the incidence of fibrinolytic therapy during the COVID-19 pandemic and its effects on STEMI clinical outcomes. METHODS: PubMed, Google Scholar, Scopus, Web of Science, and Cochrane Central Register of Controlled Trials were queried from January 2020 up to February 2022 to identify studies investigating the effect of fibrinolytic therapy on the prognostic outcome of STEMI patients during the pandemic. Primary outcomes were the incidence of fibrinolysis and the risk of all-cause mortality. Data were meta-analyzed using the random effects model to derive odds ratios (OR) and 95% confidence intervals. Quality assessment was carried out using the Newcastle-Ottawa scale. RESULTS: Fourteen studies including 50136 STEMI patients (n = 15142 in the pandemic arm; n = 34994 in the pre-pandemic arm) were included. The mean age was 61 years; 79% were male, 27% had type 2 diabetes, and 47% were smokers. Compared with the pre-pandemic period, there was a significantly increased overall incidence of fibrinolysis during the pandemic period [OR: 1.80 (1.18 to 2.75); I2= 78%; P = 0.00; GRADE: Very low]. The incidence of fibrinolysis was not associated with the risk of all-cause mortality in any setting. The countries with a low-and middle-income status reported a higher incidence of fibrinolysis [OR: 5.16 (2.18 to 12.22); I2 = 81%; P = 0.00; GRADE: Very low] and an increased risk of all-cause mortality in STEMI patients [OR: 1.16 (1.03 to 1.30); I2 = 0%; P = 0.01; GRADE: Very low]. Meta-regression analysis showed a positive correlation of hyperlipidemia (P = 0.001) and hypertension (P \u3c 0.001) with all-cause mortality. CONCLUSION: There is an increased incidence of fibrinolysis during the pandemic period, but it has no effect on the risk of all-cause mortality. The low- and middle-income status has a significant impact on the all-cause mortality rate and the incidence of fibrinolysis