Failure of evaporator tubes initiated by lamellar tearing during the commissioning of a waste heat recovery boiler

Successive failures of several new evaporator tubes during commissioning and trial run of a waste heat recovery boiler has been analyzed. The evaporator tubes are cold bent into U-shape and subsequently TIG welded to a 24-mm thick wear plate on either sides of the tube immediately adjacent to the bend. The failed samples showed stepped longitudinal cracks along the rolling direction and parallel to the weld fusion boundary at the fireside surface of the inner bend of the tube,prominently at the center of the bend. It was found that the failure of the evaporator tubes at the tube bends was initiated by lamellar tearing because of inherent defects in the material (segregation leading to banded structure), improper processing of material (inclusions with high aspect ratios along the rolling direction) and accelerated by high transverse shrinkage stresses over the entire bend portion of the tube introduced by the weld. The pre-existing fine cracks in the welded evaporator tube initiated by lamellar tearing have subsequently opened up during service when the total strain in the region increased because of steam pressure resulting in catastrophic failure of the tubes. Contrary to expectation, many of the elongated inclusions were found to be iron oxide scales and only few were manganese sulfide stringers enveloped by iron oxide scales. The iron oxide inclusions were resolved from the manganese sulfide by scanning electron microscopy and EDS spot analysis of the inclusions

A systematic review of the pharmacological modulation of autobiographical memory specificity

BACKGROUND: Over-general autobiographical memory (AM) retrieval is proposed to have a causal role in the maintenance of psychological disorders like depression and PTSD. As such, the identification of drugs that modulate AM specificity may open up new avenues of research on pharmacological modeling and treatment of psychological disorders. AIM: The current review summarizes randomized, placebo-controlled studies of acute pharmacological modulation of AM specificity. METHOD: A systematic search was conducted of studies that examined the acute effects of pharmacological interventions on AM specificity in human volunteers (healthy and clinical participants) measured using the Autobiographical Memory Test. RESULTS: Seventeen studies were identified (986 total participants), of which 16 were judged to have low risk of bias. The presence and direction of effects varied across drugs and diagnostic status of participants (clinical vs. healthy volunteers). The most commonly studied drug-hydrocortisone-produced an overall impairment in AM specificity in healthy volunteers [g = -0.28, CI (-0.53, -0.03), p = 0.03], although improvements were reported in two studies of clinical participants. In general, studies of monoamine modulators reported no effect on specificity. CONCLUSION: Pharmacological enhancement of AM specificity is inconsistent, although monaminergic modulators show little promise in this regard. Drugs that reduce AM specificity in healthy volunteers may be useful experimental-pharmacological tools that mimic an important transdiagnostic impairment in psychological disorders. SYSTEMATIC REVIEW REGISTRATION: PROSPERO, identifier CRD42020199076, https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42020199076

Pharmacotherapeutic Options for Visceral Leishmaniasis—Current Scenario

Visceral leishmaniasis (VL) or Kala-azar is a protozoal disease, which was previously regarded as one of the most neglected tropical diseases. Management of this disease is quite difficult, because it is said to affect the poorest of the poor. Previously Sodium Stibogluconate (SSG) was regarded as the gold standard treatment for VL. But due to the increasing unresponsiveness, to this drug various other drugs were tried and are still being tried. Pentamidine is very toxic and has been discarded of late. Amphotericin B and its lipid formulations are very effective but require hospital admission and monitoring. Oral drugs like Miltefosine have already been launched. An amino glycoside Paromomycin and another oral drug Sitamaquine are in the pipe line. Interferon gamma has been used with discouraging results

Accelerated forgetting of a trauma-like event in healthy men and women after a single dose of hydrocortisone

Posttraumatic stress disorder (PTSD) is characterised by dysregulated hypothalamic-pituitary-adrenal axis activity and altered glucocorticoid receptor sensitivity. Early treatment with glucocorticoids may reduce PTSD risk, although the effect of such treatment on the aetiologically critical step of traumatic-memory-formation remains unclear. Here we examine the effects of exogenous cortisol (hydrocortisone) in a preclinical model of PTSD, using a factorial (Drug × Sex), randomised-controlled, double-blind design. Healthy men and women (n = 120) were randomised to receive 30 mg oral hydrocortisone or matched placebo immediately after watching a stressful film. Effects on film-related intrusions were assessed acutely in the lab, and ecologically using daily memory diaries for one week. We found that participants receiving hydrocortisone showed a faster reduction in daily intrusion frequency. Voluntary memory was assessed once, at the end of the week, but was unaffected by hydrocortisone. Exploratory analyses indicated sex-dependent associations between intrusions and baseline estradiol and progesterone levels. In men receiving hydrocortisone, higher baseline estradiol levels were associated with fewer intrusions, whereas women exhibited the opposite pattern. By contrast, progesterone levels were positively associated with intrusions only in men treated with hydrocortisone. The findings suggest that hydrocortisone promotes an accelerated degradation of sensory-perceptual representations underlying traumatic intrusive memories. In addition, while sex alone was not an important moderator, the combination of sex and sex-hormone levels (especially estradiol) influenced hydrocortisone’s effects on involuntary aversive memories. Future well-powered experimental studies may provide a basis for a precision-psychiatry approach to optimising early post-traumatic glucocorticoid treatments that target intrusive memories, based on individual endocrinological profiles

Effects of Cold Deformation Prior to Sensitization on Intergranular Stress Corrosion Cracking of Stainless Steel

The effects of deformation, prior to sensitization, on intergranular stress corrosion cracking (IGSCC) were studied on the AISI 304 (UNS S30400) stainless steel (SS). The degree of sensitization (DOS) was quantified by the double loop electrochemical potentiokinetic reactivation (DL-EPR) method. The susceptibility to IGSCC was investigated by the slow strain rate test (SSRT) carried out in polythionic acid (PTA) solutions. The results were complemented by scanning electron microscopy (SEM) fractographs. Deformation was found to accelerate sensitization, and a peak in sensitization vs. deformation was always observed. This peak was found to shift toward lower deformations with an increase in sensitization temperature. At 700°C, prior deformation is able to desensitize or heal the SS after 24 h. IGSCC was observed in AISI 304 SS after some treatments. No one-to-one correspondence was observed between IGSCC and DOS; this could be explained by the fact that the DOS measured by the DL-EPR indicates the depleted regions below ~15% Cr, whereas IGSCC depends on the availability of continuous grain boundary paths that are chromium-depleted, along with strain rate and environment (pH, temperature, etc.). Deformation prior to sensitization causes carbide formation and chromium depletion to occur near dislocations within the grain interiors, in addition to along grain boundaries. The DOS does not differentiate between these interior regions and the grain boundary regions, and shows Sensitization is a common phenomenon in stainless steels (SS) when they are exposed to temperatures ranging from about 400°C to 800°C.1-20 Classical sensitization results from the nucleation and growth of chromium carbide along grain boundaries (in solution-annealed SS and nickel alloys) with simultaneous depletion of chromium in adjacent grain boundary regions. The extent of chromium depletion in near grain boundary regions is limited by the equilibrium concentration of chromium at the carbide-matrix interface. The equilibrium chromium level depends on the temperature, the chromium activity coefficient, the carbon activity, and the equilibrium constant for carbide formation. Hall and Briant showed the equilibrium chromium concentrations to be 6.6, 8.4, and 10.8 wt% in AISI 316LN(1) (UNS S31603)(2) sensitized at 600, 650, and 700°C, respectively.21 Sensitization occurs in the temperature range where carbide is thermodynamically stable (500°C)

Intergranular Corrosion of Deformed SS304

Intergranuular corrosion (IGC) and intergranular stress corrosion cracking (IGSCC) of commercial stainless steels e.g. type 304 and 316 are frequently observed in several process environments. These localized attacks are normally attributed to the carbide precipitation and concomitant depletion of chromium near grain boundary due to alloy exposure to sensitization temperature. Such undesirable microchemistry is expected to be changed further if the material undergoes deformation prior to sensitization

Nature of fireside deposits in a bagasse and groundnut shell fired 20 MW thermal boiler

The nature of deposit formation on the fireside surfaces of the boiler tubes in the various parts (water walls, platen superheater, final superheater, economizer, electrostatic precipitator etc.) of a commercial 20 MW stoker-fired boiler being fired with a mixture of 80% bagasse and 20% groundnut shell has been analyzed. The deposits in the various portions of the boiler were characterized by particle size analysis, chemical analysis, X-ray diffraction and scanning electron microscopy. The deposits were found to be mainly quartz, alkali and alkaline earth silicates and sulfates. From the phase constitution and other microscopic characteristics of the deposit, it can be inferred that the silicates in the deposit formed through inertial impaction and the sulfates formed by vapor phase deposition

Contesting restrictive mobility norms among female mentors implementing a sport based programme for young girls in a Mumbai slum.

BACKGROUND: Harmful gender norms are known structural barriers to many public health and development interventions involving adolescent girls. In India, restrictions on girls' liberty to move freely in public spaces contribute to school dropout and early marriage, and negatively affect girls' health and wellbeing, from adolescence into adulthood. We report on mechanisms of change among female mentors 18 to 24 years old who contested discriminatory norms while implementing a sports-based programme for adolescent girls in a Mumbai slum. METHODS: We adopted a prospective qualitative research design. Our analysis is based on case studies derived from two rounds of face to face, in -depth interviews with 10 young women recruited to serve as mentors for the project's young female athletes. We combined both thematic and narrative analysis. RESULTS: The programme created opportunities for collective action, increasing mentors' ability to think and relate in a collectivized manner, and challenged the traditional female identity constructed for young women, which centres on domestic duties. The mentors themselves negotiated freedoms both in and outside their homes, which required careful and strategic bargaining. They changed the nature of key day-to-day social interactions with parents and brothers, as well as with neighbours, parents of their groups of athletes and men on the streets. They formed a new reference group for each other in terms of what was possible and acceptable. Demonstrating greater negotiation skills within the family helped win parents' trust in the mentor's ability to be safe in public spaces. Parents became active supporters by not giving into social sanctions of neighbours and relatives thus co-producing a new identity for their daughters as respectable young women doing 'good work'. They effectively side stepped reputational risk with their presence in public spaces becoming de-sexualised. CONCLUSIONS: Mentors contested mobility restrictions by taking risks as a group first, with collective agency an important step towards greater individual agency. This research provides important insights into addressing embedded social norms that perpetuate gender discriminatory practices and the social patterning of health inequalities

In-Situ Fabrication of Ceramic Matrix Composites by RH-SHS Technique

A rapid heating self propagating high temperature synthe-sis (RII-SHS) technique is developed for the fabrication of in-situ A1203 -SiC„ composites. The adiabatic tempera-ture for the system is calculated to be 2375 K. The green compacts are heated rapidly (w 300 - 400 K/min) from room temperature to various soaking temperatures (T,) ranging from 1473 to 2023 K either in air or argon atmosphere. Two exothermic reactions are observed successively during synthesis. XRD analyses show that the reduction of SiO2 proceeds through aluminothermic route and a holding time of = 30 minutes at T, is sufficient for the completion of reactions. SiC is observed to be present in the form of a-Sic, and the size and proportion of the whiskers depends upon the soaking time and temperature. Dimensional stabi-lity of the sintered products indicates the possibility of near net shape fabrication of composites using this technique