Comparative characterization of P91 and 10CrMo9-10 creep resistant steel welds

Abstract:Abstract: P91 and 10CrMo9-10 creep resistant steels are critical to the performance of boiler tubes and power generating plants in general. Components made from these materials are mainly joined by welding. This paper reports on the comparative study of the effect of TIG and SMAW welding on the mechanical performance of P91 and 10CrMo9-10. TIG was used for root welding while SMAW was used for weld filling of V-butt joints. Specimens of the two alloys prepared using recommended welding procedures are evaluated using optical microscopy and Vickers micro hardness assessment. Some specimens were post weld heat treated while others were not. Post weld heat treated (PWHT) specimens exhibited similar properties as the corresponding base materials for both steels. TIG welding resulted in significant grain size reduction in both steels. PWHT produced more consistent grain structure, which is favorable

Flow Visualization of Two-Phase R-245fa at Low Mass Flux in a Plate Heat Exchanger near the Micro-Macroscale Transition

Two-phase R-245fa flow in a plate heat exchanger is experimentally investigated to understand the unique flow regimes found during operation at low refrigerant mass flux. A transparent plate heat exchanger replica with 3.4 mm hydraulic diameter is 3D-printed for flow visualization using high-speed videography. Observed flow regimes support that the thermofluidic characteristics peculiar to plate heat exchanger (PHE) operation are due to the macro-microscale transitional two-phase flow from the coexistence of fluid inertial force and surface tension effects, corresponding to the operation conditions. Maximum stable bubble diameter is bigger at low mass flux than at high mass flux, and the bubbles can become big enough to be fully confined in the millimeter-scale PHE channel to be deformed or elongated. This represents the main thermo-physical characteristics of two-phase flow in mini- and microchannels, which is different from turbulent mixing flow easily found at high-mass-flux operation or in channels of conventional macroscale. Flow morphology involving complex bubble coalescence and breakup dynamics is captured and analyzed in relation to the fluid properties and geometric obstructions provided by the plate heat exchanger channel. While there exist previous studies, and even heat transfer coefficient correlations, suggesting the potential microscale flow regimes in PHEs, this is the first time presenting evidences via flow visualization

Compounded laxative formulations for substituting phenolphthalein with sennosides A & B in solid dosage forms

Purpose: Following the discovery of the carcinogenicity of phenolphthalein and the subsequent ban of this compound in several countries this study was undertaken to develop compounded formulations of laxative products containing the stimulant laxatives sennosides A and B. Methods: DSC and HPLC analysis was used to determine the compatibility of sennosides with commonly used excipients before compounding capsules, tablets and effervescent tablets containing sennosides A & B. The physical and chemical stability and release properties of these dosage forms were determined for 12 weeks at increased temperature and relative humidity. Results: Sennosides A & B were compatible with a wide variety of powdered excipients. However, these were incompatible with propyl paraben, sodium carbonate, stearic acid, citric acid, PEG, and sugar derivatives such as lactose, glucose and sorbitol when granulated with water. Not withstanding these interactions, it was possible to compound simple capsule, tablet and even an effervescent tablet formulations containing sennosides A & B that complied with pharmacopeial specifications. However, all these formulations were sensitive to moisture because when stored at increased temperature and relative humidity, disintegration times increased and dissolution rates decreased. Conclusion: Based on compatibility and stability studies simple, stable and elegant solid dosage forms containing sennosides A & B were compounded that can be used to replace phenolphthalein in a variety of solid dosage forms. Keywords: Compounding; Sennosides A & B; Phenolphthalein replacement; Drug-Excipient Compatibility > Tropical Journal of Pharmaceutical Research Vol. 3 (1) 2004: pp. 265-27

Re-evaluating the taxonomic status of Phaeoisariopsis griseola, the causal agent of angular leaf spot of bean

Angular leaf spot of Phaseolus vulgaris is a serious disease caused by Phaeoisariopsis griseola, in which two major gene pools occur, namely Andean and Middle-American. Sequence analysis of the SSU region of nrDNA revealed the genus Phaeoisariopsis to be indistinguishable from other hyphomycete anamorph genera associated with Mycosphaerella, namely Pseudocercospora and Stigmina. A new combination is therefore proposed in the genus Pseudocercospora, a name to be conserved over Phaeoisariopsis and Stigmina. Further comparisons by means of morphology, cultural characteristics, and DNA sequence analysis of the ITS, calmodulin, and actin gene regions delineated two groups within P. griseola, which are recognised as two formae, namely f. griseola and f. mesoamericana

A scoping review: Identifying targeted intervention strategies for workers with occupational hearing loss

An apparent disconnect exist in workplaces regarding identification of occupational hearing loss (OHL) and implementation of specific strategies to prevent progression of OHL, evident through continued high incidence of OHL. This scoping review aimed to identify evidence regarding targeted intervention used by industry, specifically to prevent the progression of OHL for workers. The scoping review was undertaken using the PRISMA-ScR methodology. Search terms were based on three broad categories, hearing loss, workplace, and intervention. Initially 1309 articles were identified for screening and 1,207 studies not meeting the criteria were excluded. Full text reviews of 102 articles were completed and a further 93 studies excluded. The scoping review produced nine studies which were quantitatively analysed. All interventions focused primarily on lower order controls, specifically administrative and personal protective equipment. Eight studies focused on awareness training, health monitoring, mandating hearing protection device use and fit testing, and using personal attenuation ratings as a predictor to OHL. Only one study mentioned isolation of workers from noise sources, and this was an interview study with workplace managers, not a specific intervention at a workplace. The result of the review highlights the lack of published literature on targeted interventions for workers with OHL. There is insufficient evidence to inform effective, impactful change in practice to prevent the progression of OHL. It is recommended that a system of collecting and assessing specific interventions and controls for workers with OHL be developed to better inform industry on strategies that will provide adequate protection for these workers

Influence of Apple stem grooving virus on Malus sieboldii-derived apple proliferation resistant rootstocks

Apple stem grooving virus (ASGV, Capillovirus) is widely spread in apple growing regions. As it causes no symptoms on most cultivated apple varieties and rootstocks it is considered latent in Malus x domestica. In Asia, however, ASGV has been found associated with topworking disease of apple rootstocks originating from Malus sieboldii. Recently, M. sieboldii and its hybrids have gained new interest in Europe as they confer resistance to apple proliferation (AP) disease. A new breeding program aiming to develop AP-resistant rootstocks of agronomic value for modern apple culture, reported unexpected tree decline which was to be associated with ASGV. As little information is available on the variability of ASGV isolates in Germany, the complete genome of a German isolate of ASGV associated with tree decline was cloned and sequenced. Sequence comparisons with available ASGV isolates revealed two regions of high variability in the genome. The genetic variability of additional isolates from Germany and other countries were collected and the variable areas characterised. In addition ASGV was successfully maintained in micropropagated apple trees and could be transmitted by in vitro grafting to various genotypes, making it possible to study in vitro the effect of the virus and virus/phytoplama combination on M. sieboldii-derived genotypes. Keywords: Latent apple viruses, Candidatus Phytoplasma mali, micropropagation, in vitro grafting, genetic variabilit

Formulation of a topical sun protection cream for people with albinism

The aim of this investigation was to design and develop a sun protection product for people with albinism that is affordable, applicable to their specific skin condition, and provide them with the maximum sun protection possible. To achieve the required Sun Protection Factor value of > 20, simple creams were combined with very fine inorganic oxides (zinc oxide and titanium dioxide) and organic sunscreen filters (2-ethylhexyl cinnamate and octyl methoxycinnamate). These combinations also ensured high UVA/UVB protection ratios. The physical stability and change in Sun Protection Factor were for products stored for 8 weeks at 25°C (60% RH) and 45°C (75% RH) were also determined. Hypoallergenic and physically stable product(s) were formulated with SPF values between 20 to 30 and UVA/UVB ratios above 0.8 by combining simple cream formulations with fine particle inorganic oxides and organic UV protection agents. This approach offered an opportunity to formulate broad-spectrum sunscreen products that met the needs of albinos.Keywords: sun protection cream, sun protection factor, albinismThe East and Central African Journal of Pharmaceutical Sciences Vol. 7(3) 2006: 60-6

South African agricultural R&D investments : sources, structure, and trends, 1910-2007

The twentieth century saw substantive shifts in the structure, funding and conduct of public agricultural research and development (R&D) and related regulatory and extension activities in South Africa. Following a long period of steady (and at times quite rapid) growth beginning in the early twentieth century, real spending on public agricultural R&D has essentially flat lined since the 1970s. There has also been an erratic pattern of funding per scientist and a loss of scientific personnel in recent decades. Notably, South Africa has lost ground relative to its competitors in international commodity markets, such as the United States (US) and Australia in terms of the intensity of investment in agricultural R&D. In the absence of changes to these trends, these developments may well have enduring, and detrimental, consequences for the productivity performance and competitiveness of South African agriculture. They deserve serious policy attention as the twenty-first century unfolds, with a firm eye to the long-run given the lengthy lags (often many decades) that typify the relationship between public agricultural R&D spending and productivity growth.The research supporting this paper was funded principally by the South African DoA and ARC, with additional support from the International Food Policy Research Institute, InSTePP, the University of Pretoria, and the Bill and Melinda Gates Foundation.http://www.tandfonline.com/loi/ragr2

Predictors of 1-year survival in South African transcatheter aortic valve implant candidates

Background. Transcatheter aortic valve implantation (TAVI) has undergone rapid expansion internationally over the past 15 years. In view of resource constraints in developing countries, a major challenge in applying this technology lies in identifying patients most likely to benefit. The development of a risk prediction model for TAVI has proved elusive, with a reported area under the curve (AUC) of 0.6 - 0.65. The available models were developed in a First-World setting and may not be applicable to South Africa (SA).Objectives. To evaluate novel indicators and to develop a TAVI risk prediction model unique to the SA context. The current work represents the important initial steps of derivation cohort risk model development and internal validation.Methods. Seven-year experience with 244 successive TAVI implants in three centres in Western Cape Province, SA, was used to derive risk parameters. All outcomes are reported in accordance with the Valve Academic Research Consortium definitions. Multiple preprocedural variables were assessed for their impact on 1-year survival using univariate and multivariate models.Results. Factors found not to correlate with 1-year survival included age, renal function and aortic valve gradients. The commonly used surgical risk prediction models (Society of Thoracic Surgeons score and EuroSCORE) showed no correlation with outcomes. Factors found to correlate best with 1-year survival on multivariate analysis were preprocedural body mass index (BMI) (favouring higher BMI), preprocedural left ventricular end-diastolic dimension (LVED) and ejection fraction (EF) (favouring smaller LVED and higher EF), absence of atrial fibrillation, and three novel parameters: independent living, ability to drive a car, and independent food acquisition/cooking. Discriminant analysis of these factors yielded an AUC of 0.8 (95% confidence interval 0.7 - 0.9) to predict 1-year survival, with resubstitution sensitivities and specificities of 72% and 71%, respectively.Conclusions. Apart from existing predictors, we identified three novel risk predictors (independent living, ability to drive a car, and independent food acquisition/cooking) for 1-year survival in TAVI candidates. These novel parameters performed well in this early evaluation, with an AUC for predicting 1-year survival higher than the AUCs for many of the internationally derived parameters. The parameters are inexpensive and easy to obtain at the initial patient visit. If validated prospectively in external cohorts, they may be applicable to other resource-constrained environments.