Developing a procedure to reduce thermal shock influence in a steam turbine due to cold start

An improved procedure is developed to reduce the thermal shock influence in a steam turbine due to a cold start operation. Thermal shock, a term used to describe the sudden imposition of a large heat flux and temperature gradient on a material surface, is a potential damage mechanism if its intensity is sufficiently high. For the case of a turbine cold start, the thermal shock intensity depends on the film coefficient and the initial temperature difference between the steam and the rotor surface. Reduction of thermal shock intensity can be achieved in several ways, such as lengthening the transit time. lowering the film coefficient, and reducing the temperature difference between the steam and the rotor surface. One of the most efficient procedures employed to control the thermal shock influence is to increase the heating steps and warm up time. A case studied in this project, the normal two-step heating operation causes a very high compressive stress, 437 MPA, on the platform during the first heating step. Sometimes its magnitude is two or three times greater than the compressive stresses during second heating step. In this two-step heating operation the first heating temperature was 204C and the total operating time for the first heating step was 75 seconds. An improved procedure, a three-step heating operation, was developed to make the stresses caused by each heating step uniform. The first heating step of the two-step heating operation was substituted by the first two heating steps of the three-step heating operation. The maximum thermal stress as a result of the improved operation was 358 MPA and the total operating time of the first two steps was 22.5 minutes. Under the 22.5 minutes operating time the optimum temperature for the first heating step was 162C, followed by another temperature increment to 204C. Another study was conducted to study the effects of thermal stresses on different film coefficients (heat transfer coefficients). Under the same operating conditions the stress did not change significantly for the film coefficients from 50% to 150% of the normal operating value of 10,000 W/m-K. The thermal behavior obtained in this project will be useful for a turbine designer to ensure that no propagating crack would be formed within the life-time of the design machine. It is obvious that the longer the warm up time, the lower the thermal shock will be. From an economic point of view, longer warm up times are undesirable. A turbine designer needs to consider both these aspects before arriving at a strategy for the cold start

Genomic organization of ATOX1, a human copper chaperone

BACKGROUND: Copper is an essential trace element that plays a critical role in the survival of all living organisms. Menkes disease and occipital horn syndrome (OHS) are allelic disorders of copper transport caused by defects in a X-linked gene (ATP7A) that encodes a P-type ATPase that transports copper across cellular membranes, including the trans-Golgi network. Genetic studies in yeast recently revealed a new family of cytoplasmic proteins called copper chaperones which bind copper ions and deliver them to specific cellular pathways. Biochemical studies of the human homolog of one copper chaperone, ATOX1, indicate direct interaction with the Menkes/OHS protein. Although no disease-associated mutations have been reported in ATOX1, mice with disruption of the ATOX1 locus demonstrate perinatal mortality similar to that observed in the brindled mice (Mo(br)), a mouse model of Menkes disease. The cDNA sequence for ATOX1 is known, and the genomic organization has not been reported. RESULTS: We determined the genomic structure of ATOX1. The gene contains 4 exons spanning a genomic distance of approximately 16 kb. The translation start codon is located in the 3' end of exon 1 and the termination codon in exon 3. We developed a PCR-based assay to amplify the coding regions and splice junctions from genomic DNA. We screened for ATOX1 mutations in two patients with classical Menkes disease phenotypes and one individual with occipital horn syndrome who had no alterations detected in ATP7A, as well as an adult female with chronic anemia, low serum copper and evidence of mild dopamine-beta-hydroxylase deficiency and no alterations in the ATOX1 coding or splice junction sequences were found. CONCLUSIONS: In this study, we characterized the genomic structure of the human copper chaperone ATOX1 to facilitate screening of this gene from genomic DNA in patients whose clinical or biochemical phenotypes suggest impaired copper transport

Addressing Key Risk of Water Resources and Describing the Adaptation Pathways to Uncertain Future Climate Change

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchive

Precision Medicine for Frontotemporal Dementia

Frontotemporal dementia (FTD) is a common young-onset dementia presenting with heterogeneous and distinct syndromes. It is characterized by progressive deficits in behavior, language, and executive function. The disease may exhibit similar characteristics to many psychiatric disorders owing to its prominent behavioral features. The concept of precision medicine has recently emerged, and it involves neurodegenerative disease treatment that is personalized to match an individual's specific pattern of neuroimaging, neuropathology, and genetic variability. In this paper, the pathophysiology underlying FTD, which is characterized by the selective degeneration of the frontal and temporal cortices, is reviewed. We also discuss recent advancements in FTD research from the perspectives of clinical, imaging, molecular characterizations, and treatment. This review focuses on the approach of precision medicine to manage the clinical and biological complexities of FTD

Antimicrobial Susceptibility and Multiplex PCR Screening of AmpC Genes From Isolates of Enterobacter cloacae, Citrobacter freundii, and Serratia marcescens

Background/PurposeThe emergence of multiple drug resistance in Enterobacteriaceae is of particular concern. The aim of this study was to evaluate the antimicrobial susceptibility and screen for the ampC gene in three members of the Enterobacteriaceae family (Enterobacter cloacae, Citrobacter freundii, and Serratia marcescens) found at Taichung Veterans General Hospital during the past 5 years using multiplex polymerase chain reaction (PCR).MethodsThe susceptibility of thirty isolates from each of the three Enterobacteriaceae family members to five antimicrobial agents (ceftazidime, flomoxef, imipenem, moxifloxacin, and colistin) was assessed. The susceptibility was analyzed by disk diffusion, screening and confirmatory tests for extended-spectrum β-lactamases (ESBL) and minimum inhibitory concentration tests according to the recommendations of the Clinical and Laboratory Standards Institute. The detection of ampC genes (3 families, including DHA, EBC and CIT) was performed by multiplex PCR. To detect the coexistence of ESBL genes, PCR was performed using five primer pairs: TEM, SHV, SHV-5, CTX-M-3, and CTX-M-14.ResultsOf the 90 isolates, 53 (58.9%) were positive in the screening test for ESBL. Resistance genes were detected in 12 (22.6%) of these isolates: ampC gene of DHA type in one E. cloacae isolate and EBC type in three E. cloacae isolates; ampC gene of CIT type in four C. freundii isolates; CTX-M-3-like in one C. freundii isolate and one S. marcescens isolate; TEM in three E. cloacae isolates, three C. freundii isolates and two S. marcescens isolates; SHV in one C. freundii isolate.ConclusionAntibiotic phenotypes cannot accurately distinguish the resistance mechanisms caused by ampC or ESBL, and especially in ESBL-ampC combinations. However, PCR is a useful technique for the identification of the different types of resistance genes

Childhood tuberculosis in southern Taiwan, with emphasis on central nervous system complications

Background/PurposeChildhood tuberculosis (TB) continues to be a major public health problem in Taiwan. Taiwan remains a highly endemic area despite neonatal Bacillus Calmette–Guérin (BCG) vaccination and the availability of anti-TB therapy. The presentation is highly variable and it is often difficult to make an accurate diagnosis. This study was designed to evaluate the demographic, clinical, and laboratory findings and outcomes of TB in children with emphasis on central nervous system (CNS) complications.MethodsThe medical records of 80 children diagnosed with TB at a medical center in southern Taiwan over the past 24 years (1988–2012) were reviewed.ResultsAmong them, 48.8% (39/80) had pulmonary TB, 27.5% (22/80) had isolated extrapulmonary TB, and 23.7% (19/80) had disseminated TB. Most infected cases were aged either < 4 years or > 12 years. TB contact history was found in 42.5% (34/80) cases. Fourteen (17.5%) of the cases had CNS involvement. The most common presentations were fever (85.7%), signs of increased intracranial pressure (71.4%), drowsiness (64.3%), and focal neurological signs (57.1%). The major radiological findings were tuberculoma (50%), basilar enhancement (41.6%), infarction (41.6%), hydrocephalus (16.6%), and transverse myelitis (16.6%). The case fatality of CNS TB was 14.3% and 21.4% had neurologic sequelae.ConclusionFindings suggest that positive exposure history and suspicious clinical presentations are important clues for further confirmatory laboratory and image studies in childhood TB. CNS TB usually presented as part of disseminated TB in children. Early diagnosis and treatment may lead to favorable outcomes in CNS TB

The Related Effects of Increased PN Junction Area on ESD Protection Capability

ESD protection devices comprising polysilicon resistor, Vcc and Vss connected diodes with different sizes of PN junction area were fabricated on CMOS test chip and underwent ESD stress. The result of testing shows that larger PN junction area will subject the polysilicon resistor to bear more energy from ESD stress and end up with more failures. The relationship between stressing energy and junction area is hereby derived. Different failure modes for positive and negative ESD pulses are also identified. By comparing our own design with those of commercial designs, a safe length of contacting parameter at Al-polysilicon contact capable of handling the discharging current is identified to be more than 90 μm

Comparison of secondary signs as shown by unenhanced helical computed tomography in patients with uric acid or calcium ureteral stones

AbstractUnenhanced helical computed tomography (UHCT) has evolved into a well-accepted diagnostic method in patients with suspected ureterolithiasis. UHCT not only shows stones within the lumen of the ureter, it also permits evaluation of the secondary signs associated with ureteral obstruction from stones. However, there we could find no data on how secondary signs might differ in relation to different compositions of ureteral stones. In this study, we compared the degree of secondary signs revealed by UHCT in uric acid stone formers and in patients forming calcium stones. We enrolled 117 patients with ureteral stones who underwent UHCT examination and Fourier transform infra-red analysis of stone samples. Clinical data were collected as follows: age, sex, estimated glomerular filtration rate (eGFR), urine pH, and radiological data on secondary signs apparent on UHCT. The uric acid stone formers had significantly lower urine pH and eGFR in comparison to calcium stone formers, and on UHCT they also had a higher percentage of the secondary signs, including rim sign (78.9% vs. 60.2%), hydroureter (94.7% vs. 89.8%), perirenal stranding (84.2% vs. 59.2%) and kidney density difference (73.7% vs. 50.0%). The radiological difference was statistically significant for perirenal stranding (p=0.041). In conclusion, we found that UHCT scanning reveals secondary signs to be more frequent in patients with uric acid ureteral stones than in patients with calcium stones, a tendency that might result from an acidic urine environment

Simple Yet Powerful Native Language Identification on TOEFL11

Abstract Native language identification (NLI) is the task to determine the native language of the author based on an essay written in a second language. NLI is often treated as a classification problem. In this paper, we use the TOEFL11 data set which consists of more data, in terms of the amount of essays and languages, and less biased across prompts, i.e., topics, of essays. We demonstrate that even using word level n-grams as features, and support vector machine (SVM) as a classifier can yield nearly 80% accuracy. We observe that the accuracy of a binary-based word level ngram representation (~80%) is much better than the performance of a frequency-based word level n-gram representation (~20%). Notably, comparable results can be achieved without removing punctuation marks, suggesting a very simple baseline system for NLI