An Alternative Approach to the Fracture Toughness of Dual Phase Steels

In this study, the effects of ferrite morphology and of ferrite volume fraction on the mechanical properties and the fracture toughness values ( ) KIc of dual phase steels were investigated. The fracture toughness values were determined using an approach that was different from the standard one. A homogenization heat treatment was applied to the steels. Two different starting microstructures were then obtained by either the full annealing of or the quenching of the steels from austenite before applying intercritical annealing to the steels in the austenite region. After this process, dual phase steels with two types of morphology, coarse and fine, were obtained with 40, 20, and 10% ferrite volume fractions, depending on the starting microstructure. Tempered specimens with 10% ferrite exhibited improved fracture toughness values compared with those of the other steels.Исследуется влияние морфологии структуры феррита и его объемного содержания на механические свойства и вязкость разрушения двухфазных сталей. Для определения значений вязкости разрушения использовали не стандартный, а альтернативный подход. Стали подвергали гомогенизирующей термообработке. Путем полного отжига или закалки сталей из аустенитного состояния до применения докритического отжига в аустенитной области получены две различные исходные микроструктуры. Получены двухфазные стали с двумя типами морфологии (крупно- и мелкозернистая) с 40-, 20- и 10%-ным объемным содержанием феррита в зависимости от исходной микроструктуры. Отпущенные образцы с 10%-ным объемным содержанием феррита имели более высокие значения вязкости разрушения по сравнению с таковыми других образцов из этих сталейДосліджується вплив морфології структури фериту та його об’ємного вмісту на механічні властивості і в’язкість руйнування двофазних сталей. Для визначення значень в’язкості руйнування використовували не стандартний, а альтернативний підхід. Сталі піддавали гомогенізуючій термообробці. Шляхом повного відпалу або загартування сталей з аустенітного стану до використання докритичного відпалу в аустенітній області отримано дві різні початкові мікроструктури. Отримано двофазні сталі з двома типами морфології (великоі дрібнозеренна) з 40-, 20- і 10%-ним об’ємним вмістом фериту в залежності від початкової мікроструктури. Відпущені зразки з 10%-ним об’ємним вмістом фериту мали більш високі значення в’язкості руйнування порівняно з такими інших зразків із цих сталей

High-Speed High Effiency Large Area Resonant Cavity Enhanced p-I-n Photodiodes for Multimode Fiber Communications

Cataloged from PDF version of article.In this letter, we report AlGaAs–GaAs p-i-n photodiodes with a 3-dB bandwidth in excess of 10 GHz for devices as large as 60- m diameter. Resonant cavity enhanced photodetection is employed to improve quantum efficiency, resulting in more than 90% peak quantum efficiency at 850 nm

High-speed >90% quantum-efficiency p–i–n photodiodes with a resonance wavelength adjustable in the 795–835 nm range

Cataloged from PDF version of article.We report GaAs/AlGaAs-based high-speed, high-efficiency, resonant cavity enhanced p–i–nphotodiodes. The devices were fabricated by using a microwave-compatible fabrication process. By using a postprocess recess etch, we tuned the resonance wavelength from 835 to 795 nm while keeping the peak efficiencies above 90%. The maximum quantum efficiency was 92% at a resonance wavelength of 823 nm. The photodiode had an experimental setup-limited temporal response of 12 ps. When the system response is deconvolved, the 3 dB bandwidth corresponds to 50 GHz, which is in good agreement with our theoretical calculations. © 1999 American Institute of Physic

Hypertensive Disorders of Pregnancy are Associated with Differences in Maternal Serum Concentrations of Arachidonic Acid Metabolites

Background: Hypertensive disorders of pregnancy (HDP), including gestational hypertension, chronic hypertension, and preeclampsia, are a significant cause of maternal morbidity and mortality in the United States. Dysregulation of inflammation is thought to play a role in the development of HDP. Maternal diet has the potential to alter the risk of HDP by modulating inflammation. Arachidonic acid (AA) is a dietary polyunsaturated fatty acid which can be metabolized into both pro- and anti-inflammatory bioactive metabolites. Significance of Problem: HDP places women and their infants at risk for potentially severe pregnancy complications including placental abruption, embolism, end-organ failure, or death. Few treatments are currently available for HDP. Question: The objective of this study was to describe how maternal AA metabolites serum concentrations are associated with diagnosis of HDP. Experimental Design: Serum was collected from 121 pregnant women admitted to the labor and delivery unit at Nebraska Medical Center. Women were divided into normotensive or hypertensive groups based on definitions from the American College of Obstetricians and Gynecologists (ACOG). Concentrations of AA metabolites were measured using liquid chromatography-mass spectrometry. Descriptive statistics were generated, and Mann-Whitney U tests were used to compare metabolite concentrations between groups. Results: Women with HDP had significant higher serum concentrations of PGF2α (p=0.02) and 15-HETE (p=0.04), two metabolites with known inflammatory and vasoconstrictive properties. Women with HDP had significantly lower serum concentrations of 8(9)-DiHET (p=0.04), 11(12)-DiHET (p=0.04), and 14(15)-DiHET (p=0.001), which are all associated with vasodilation. Unexpectantly, hypertensive mothers also had lower serum concentrations of 5-HETE (p=0.02), which is associated with vasoconstriction. Conclusion: Overall, our study reveals that mothers diagnosed with HDP had significantly higher serum concentrations of vasoconstrictive AA metabolites and significantly lower serum concentrations of vasodilating AA metabolites compared to normotensive mothers. Future directions include analyzing differences in maternal metabolite profile separately for mothers with chronic hypertension, gestational hypertension, and preeclampsia compared to normotensive mothers. Results from these analyses will guide nutritional recommendations for women at risk of developing HDP.https://digitalcommons.unmc.edu/chri_forum/1062/thumbnail.jp

An Obscure Case of Hepatic Subcapsular Hematoma

Spontaneous liver bleeding is often reported in preeclampsia. It is otherwise rare and has been linked to gross anatomical lesions and coagulopathy. We report a case of subcapsular hematoma of the liver without any apparent lesion and in the absence of coagulopathy. A 41-year-old male, paraplegic for 16 years, presented to the emergency department 3 days after sudden onset of right upper quadrant and shoulder pain. He had been on vitamins and 5,000 units subcutaneous heparin 12-hourly at the nursing home for the last month. He was in no distress, afebrile, with stable vitals. Physical examination showed a diverting colostomy, tender hepatomegaly and sacral decubiti. A fecal occult blood test was negative. There was spastic paraplegia below the level of T12. Two days after admission, the patient was afebrile and hemodynamically stable. PTT, PT, liver profile, BUN and creatinine were all normal, however his hemoglobin had dropped from 11.3 to 7.6 g/dl. An abdominal CT scan revealed an isolated 9.0 × 1.8 cm subcapsular hematoma. The patient received blood transfusion in the intensive care unit and was discharged 7 days later. In conclusion, spontaneous liver hemorrhage occurs in the nonobstetrical population in the setting of gross anatomical lesions or coagulopathy. This is the first report of an isolated subcapsular liver hematoma

Palaeozoic-Recent geological development and uplift of the Amanos Mountains (S Turkey) in the critically located northwesternmost corner of the Arabian continent

<p>We have carried out a several-year-long study of the Amanos Mountains, on the basis of which we present new sedimentary and structural evidence, which we combine with existing data, to produce the first comprehensive synthesis in the regional geological setting. The ca. N-S-trending Amanos Mountains are located at the northwesternmost edge of the Arabian plate, near the intersection of the African and Eurasian plates. Mixed siliciclastic-carbonate sediments accumulated on the north-Gondwana margin during the Palaeozoic. Triassic rift-related sedimentation was followed by platform carbonate deposition during Jurassic-Cretaceous. Late Cretaceous was characterised by platform collapse and southward emplacement of melanges and a supra-subduction zone ophiolite. Latest Cretaceous transgressive shallow-water carbonates gave way to deeper-water deposits during Palaeocene-Eocene. Eocene southward compression, reflecting initial collision, resulted in open folding, reverse faulting and duplexing. Fluvial, lagoonal and shallow-marine carbonates accumulated during Late Oligocene(?)-Early Miocene, associated with basaltic magmatism. Intensifying collision during Mid-Miocene initiated a foreland basin that then infilled with deep-water siliciclastic gravity flows. Late Miocene-Early Pliocene compression created mountain-sized folds and thrusts, verging E in the north but SE in the south. The resulting surface uplift triggered deposition of huge alluvial outwash fans in the west. Smaller alluvial fans formed along both mountain flanks during the Pleistocene after major surface uplift ended. Pliocene-Pleistocene alluvium was tilted towards the mountain front in the west. Strike-slip/transtension along the East Anatolian Transform Fault and localised sub-horizontal Quaternary basaltic volcanism in the region reflect regional transtension during Late Pliocene-Pleistocene (<4 Ma).</p

Development and validation of stability indicating method for determination of sertraline following ICH guidlines and its determination in pharmaceuticals and biological fluids

<p>Abstract</p> <p>Background</p> <p>Sertraline is a well known antidepressant drug which belongs to a class called selective serotonin reuptake inhibitor. Most published methods do not enable studying the stability of this drug in different stress conditions.</p> <p>Results</p> <p>Two new methods were developed for the determination of sertraline (SER). Both methods are based on coupling with 4-chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) in borate buffer of pH 7.8 and measuring the reaction product spectrophotometrically at 395 nm (Method I) or spectrofluorimetrically at 530 nm upon excitation at 480 nm (Method II). The response-concentration plots were rectilinear over the range 2-24 μg/mL and 0.25-5 μg/mL for methods I and II respectively with LOD of 0.18 μg/mL and 0.07 μg/mL, and LOQ of 0.56 μg/mL and 0.21 μg/mL for methods I and II, respectively.</p> <p>Conclusion</p> <p>Both methods were applied to the analysis of commercial tablets and the results were in good agreement with those obtained using a reference method. The fluorimetric method was further applied to the in vivo determination of SER in human plasma. A proposal of the reaction pathway was presented. The spectrophotometric method was extended to stability study of SER. The drug was exposed to alkaline, acidic, oxidative and photolytic degradation according to ICH guidelines. Moreover, the method was utilized to investigate the kinetics of oxidative degradation of the drug. The apparent first order rate constant and t_1/2of the degradation reaction were determined.</p