Limited tumor involvement found at multiple endocrine neoplasia type I pancreatic exploration: can it be predicted by preoperative tumor localization?

Radiologically demonstrable pancreatic endocrine tumors are a frequent requirement for exploration in patients with multiple endocrine neoplasia type I (MEN-I). Such delayed intervention is accompanied by a 30% to 50% incidence of pancreatic endocrine metastases. This study explores biochemical tumor markers and operative findings in relation to preoperative pancreatic radiology in 25 MEN-I patients. They underwent pancreatic surgery with (n = 19) or without (n = 6) radiologic signs of primary tumor and absence of metastases upon conventional examination, including OctreoScan testing (n = 10). Biochemical diagnosis required an increasing elevation of at least two independent pancreatic tumor markers. Tumor diameters averaged 1.1 cm (0-5 cm) and 0.9 cm (0.2-1.5 cm) in the patients with and without positive preoperative radiology, respectively. These investigations never displayed more than one of the consistently multiple tumors, and the results were falsely positive in 26%. Preoperatively unidentified regional or hepatic metastases were found at surgical exploration in 26% of patients with radiologic localization and in none of the others. Limited pancreatic tumor involvement necessitated intraoperative absence of metastases and pancreatic lesions /= 7 mm in diameter. Conventional pancreatic imaging is insensitive and nonspecific for recognizing even substantial pancreatic tumors associated with MEN-I.     

Performance effect on the TEG system for waste heat recovery in automobiles using ZnO and SiO2 nanofluid coolants

Enhancement in heat transfer of the cold side is vital to amplify the performance of a thermoelectric generator (TEG). With enriched thermophysical properties of nanofluids, significant improvement in heat transfer process can be obtained. The current study concerns the performance comparison of an automobile waste heat recovery system with EG‐water (EG‐W) mixture, ZnO, and SiO₂ nanofluid as coolants for the TEG system. The effects on performance parameters, that is, circuit voltage, conversion efficiency, and output power with exhaust inlet temperature, the total area of TEG, Reynolds number, and particle concentration of nanofluids for the TEG system have been investigated. A detailed performance analysis revealed an increase in voltage, power output, and conversion efficiency of the TEG system with SiO ₂ nanofluid, followed by ZnO and EG‐W coolants. The electric power and conversion efficiency for SiO ₂ nanofluid at an exhaust inlet temperature of 500K were enhanced by 11.80% and 11.39% respectively, in comparison with EG‐W coolants. Moreover, the model speculates that an optimal total area of TEGs exists for the maximum power output of the system. With SiO ₂ nanofluid as a coolant, the total area of TEGs can be diminished by up to 34% as compared with EG‐W, which brings significant convenience for the placement of TEGs and reduces the cost of the TEG system.     

The effect of polyvinyl alcohol functionalized multiwall carbon nanotubes on the improvement of the compressive strength of concrete

Abstract

Multiwalled carbon nanotubes were functionalized by polyvinyl alcohol in order to synthesize potential additive for concrete to improve mechanical properties. The obtained nanostructure was characterized structurally and surface morphologically by various techniques. These techniques revealed the success of the functionalization process in preparation of the strengthening additive. The mechanical characterization of the concrete composite obtained by the addition of the strengthening additive was performed by the compressive strength method. The results show significant positive effects of the synthesized additive material on the mechanical properties of the prepared concrete composite over the reference material. The novelty of this work is the use of the Fischer esterification reaction for the preparation of the strengthening additives for concrete using polyvinyl alcohol and multiwalled carbon nanotubes.     

Local Labor Markets and Occupational Sex Segregation in an American Metropolis

This study analyzes the reciprocal relationships between place and labor market segmentation by focusing on occupational sex segregation in Minneapolis–St. Paul. On the one hand, employment maps confirm that segmentation produces distinctive places: The slotting of women and men into different lines of work inscribes fine-grained spatial labor submarkets in different parts of the metropolis. On the other hand, logistic regression analyses confirm that place matters in segmentation processes: Workplace location significantly influences the likelihood of occupational sex segregation even after controlling for human capital and residential location factors. Occupational desegregation has advanced most rapidly with the emergence of new opportunities in suburban growth corridors. Continued suburban expansion and industrial restructuring promise increasing complexity of spatial mismatch and spatial segmentation and demand that employment policy incorporate issues of space, place, and scale.     

Ultrasound-guided 1.2-mm cutting-needle biopsies of head and neck tumours

BACKGROUND: The direct effect of halothane on vascular smooth muscle is mediated in part via its effects on the sarcoplasmic reticulum (SR). Little information is available concerning the effects of other volatile anesthetics including isoflurane and sevoflurane, whose vascular effects differ from those of halothane. The aim of the present study was to compare the effects of halothane, isoflurane and sevoflurane on the SR by testing the contraction induced by caffeine in vascular smooth muscle. METHODS: Rings without endothelium from isolated canine mesenteric artery were mounted in physiological saline solution (PSS) for isometric tension recording. After complete depletion of Ca2+ from the SR by adding 35 mM caffeine, the rings were exposed to normal Ca2+ containing PSS (Ca2+ loading), to Ca(2+)-free PSS for 10 min, and then to 15 mM caffeine to induce contraction. Anesthetics were administered during Ca2+ loading, the Ca(2+)-free phase and simultaneously with caffeine administration. RESULTS: Halothane (0.5-2%) attenuated the caffeine-induced contraction of canine mesenteric artery when administered during Ca2+ loading in the SR (P < 0.001), whereas isoflurane and sevoflurane (1-4%) failed to affect the contraction. When given simultaneously with caffeine, halothane (1-2%) potentiated the caffeine-induced contraction (P < 0.05), but isoflurane and sevoflurane had no effect. When given before caffeine administration, halothane (0.5-2%), isoflurane (2-4%) and sevoflurane (4%) all potentiated the caffeine-induced contraction (P < 0.05). CONCLUSION: It has been shown that halothane not only potentiates caffeine-induced Ca2+ release from the SR, but also induces contraction by releasing Ca2+ from the SR. We conclude that halothane decreases Ca2+ accumulation in the SR while exerting facilitative and additive effects on caffeine-induced Ca2+ release from the SR when applied before caffeine administration and simultaneously with caffeine, respectively, whereas isoflurane and sevoflurane lack both the ability to decrease Ca2+ accumulation and an additive effect on caffeine-induced Ca2+ release from the SR, but are able to facilitate Ca2+ release by caffeine.