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[en] Objective: To study the necessity of dipyridamole stress myocardial SPECT imaging before the operation in patients with dissecting aneurysm of aorta. Methods: 30 patients with diagnosed dissecting aneurysm of aorta were included. All of them underwent dipyridamole stress and rest myocardial SPECT imaging separately before operation with 1∼7 days' interval between two modalities. Two of the patients also underwent coronary angiography. Results: According to the findings in operation, of the 30 patients, 20 belonged under Debackey I and 10 under Debackey III. In the 19 patients with normal SPECT imaging, 18 had successful operations while the remaining one died of acute inferior wall infarction after operation. The mortality was 5.26%. In the 11 patients with abnormal SPECT imaging, 5 had successful operations while 6 died of cardiac insufficiency or low cardiac output syndrome. Of the 6 cases who died right in or after the operation, 5 belonged to Debackey I and 3 had sandwiches torn to the opening of the right coronary artery. Of these 3 patients, 2 had the sandwiches filled with thrombi or atheromatous plaque,the other one belonged to Debackey III accompanied by the formation of aortic atheromatous plaque. The mortality was 54.55%. Conclusions: Dipyridamole stress myocardial SPECT imaging is necessary for prognostication before operation for patients with dissecting aneurysm of aorta, especially for patients belonging to Debackey I
[en] This study involved a comprehensive thirteen month survey of synthetic musks, triclosan (TCS) and methyl triclosan (MTCS) in surface water, as well as suspended particular matter (SPM) and bottom sediments in a tropical urban catchment in Singapore. The polycyclic musk, Galaxolide (HHCB), exhibited the highest concentration among musk compounds, ranging from 5.16 to 42.9 ng/L in surface water, 11.0 to 108 ng/g dry wt. in sediments and 44.1 to 81.3 ng/g dry wt. in SPM. Concentrations of musk ketone, the dominant nitroaromatic musk, ranged from 0.08 to 6.45 ng/L in water, 0.082 to 0.72 ng/g dry wt. in sediments and 1.75 to 5.50 ng/g dry wt. in SPM. Concentrations of MTCS ranged from 0.0056 to 5.6 ng/L in water, 0.01 to 0.17 ng/g dry wt. in bottom sediments and 0.75 to 2.81 ng/g dry wt. in SPM. These concentrations are below predicted no-effect concentrations (PNEC). Principal components analysis (PCA) results showed that synthetic musk concentrations were positively correlated, indicating common source emissions. Rainfall amount and land-use index were found to be key determinants of hydrophobic organic contaminant concentrations in this catchment. Concentrations of TCS and its methylated degradation product, MTCS, were also positively correlated. However, the relative composition of MTCS to total triclosans was relatively low in water (2.8 ± 2.5%) and bottom sediments (0.3 ± 0.1%), suggesting only minor transformation of TCS to MTCS. The organic carbon-water distribution ratio, log Koc (observed), ranged between 3.8 and 5.4 for musks, TCS and MTCS, indicating relatively strong partitioning from dissolved to solid phases. These field-derived log Koc (observed) values are comparable to estimated values based on physicochemical properties. The results provide insight into the occurrence, transport pathways and exposure risks of synthetic musks, triclosan and methyl triclosan in this tropical catchment. - Highlights: • Synthetic musks, triclosan, and methyl triclosan were prevalent in the studied tropical urban catchment in both dissolved and solid phases. • Several musk compounds were highly correlated, indicating a common source • Triclosan and methyl triclosan concentrations were highly correlated • Methyl triclosan exhibited only a small fraction of total triclosans • Rainfall amount and land use index influenced contaminant concentrations • Field-derived Koc values (103.8 to 105.4) were comparable to estimated values
[en] Highlights: • Underwater superoleophobic CS/PVA coatings were prepared using a facile method. • Immersion in NaOH solution was crucial to enhance roughness of the coating surface. • Effects of coating composition on wettability of coating surface were investigated. • The CS/PVA coatings possess self-cleaning property. • The CS/PVA coatings can be used for oil/water separation with high efficiency. - Abstract: In this paper, chitosan (CS)/poly(vinyl alcohol) (PVA) coatings cross-linked with glutaraldehyde (GA) were prepared. Effects of the coating composition and NaOH solution treatment on surface morphology and topography were investigated by scanning electron microscope and atomic force microscope. It was found that the process of immersing the CS/PVA coatings into NaOH solution was crucial to enhance rough structure on the coating surface. The rough surface structure and the hydrophilic groups of CS and PVA made the CS/PVA coatings possess underwater superoleophobicity and low adhesion to oil. Oil contact angle of the prepared CS/PVA coatings was up to 161° and slide angle was only 3°. Moreover, the CS/PVA coatings showed stable superoleophobicity in high salt, strong acidic, and alkaline environments as well as underwater self-cleaning property and excellent transparency. The CS/PVA coatings could be used for gravity driven oil/water separation with high efficiency.
[en] Highlights: • A all-glass evacuated tubular solar steam generator consisted of 60 linked collecting units. • Each unit comprises a glass evacuated tube, a simplified CPC and a metal annular tube. • The maximum steam outlet temperature can exceed 200 °C with pressure of 0.55 MPa. • The performance parameters are optimized by experimental study. - Abstract: A low-cost all-glass evacuated tubular solar steam generator with simplified CPC (Compound Parabolic Concentrator) is presented in the paper. It can produce steam exceeding 200 °C with pressure ranging from 0.10 to 0.55 MPa. The solar steam generator primarily consists of 60 collecting units with a total aperture area of 32 m2 and each unit is comprised of an all-glass evacuated tube, a simplified CPC and a metal concentric annular tube which is inserted into the all-glass evacuated tube. The high viscosity mixture made of high temperature oil and graphite powder is filled in the annular space between the inner glass tube and the copper concentric tube in order to enhance heat transfer from the selective absorbing layer to working fluid flowing in the concentric tube. Outdoor experimental studies have been carried out to investigate the actual performance of the designed solar steam generator in summer time under different operating conditions. Experimental results show that the maximum steam outlet temperature can exceed 200 °C with pressure of 0.55 MPa. The present solar steam generator can steadily produce saturated steam over 150 °C at the pressure range of 0.1–0.55 MPa with a collecting efficiency over 0.30, which can be used as an industrial steam supplier with great potentials for various applications
[en] Highlights: • A novel gravity-assisted heat pipe thermal storage unit (GAHP-TSU) is presented and tested. • Composite granular solid–liquid PCM is piled up as the porous medium layer in GAHP-TSU. • GAHP-TSU avoids the major obstacle of low thermal conductivity of the PCM. • GAHP-TSU enables the thermal storage unit with outstanding heat transfer performance. - Abstract: In this study, a novel gravity-assisted heat pipe type thermal storage unit (GAHP-TSU) has been presented for the potential application in solar air conditioning and refrigeration systems, in which composite granular solid–liquid PCMs compounded by RT100 and high-density polyethylene with phase change temperature of 100 °C are piled up as a porous PCMs medium layer. Water is used as heat transfer fluid in the GAHP-TSU. The heat transfer mechanism of heat storage/release in the GAHP-TSU is similar to that of the gravity-assisted heat pipe, which is superior to traditional direct-contact or indirect-contact thermal storage units. The properties of start-up, heat transfer characteristics on the stages of heat absorption and release of the GAHP-TSU are studied in detailed, including necessary calculations based on heat transfer theory. The results show that the whole system is almost isothermal at the temperature over 70 °C and the heat transfer properties are excellent both for heat absorption and release stages. The GAHP-TSU device with low thermal conductivity of the PCMs is promising in potential industry applications
[en] Highlights: • Heating and light-irradiation cycling tests were performed on MWCNT-H2O nanofluids. • Heat treatment improved the photo-absorption capability of MWCNT-H2O nanofluids. • The extinction coefficient increased linearly with the MWCNT concentration at a wavelength range of 500–900 nm. • A temperature increase of 22.7% was achieved for the 0.01 wt% nanofluid as compared with DI water. - Abstract: Stable water-based multi-walled carbon nanotube (MWCNT) nanofluids with mass fractions ranging from 0.0015% to 0.1% were prepared. To investigate the photo-absorption properties and photo-thermal conversion performance of MWCNT-H2O nanofluids, heating and light-irradiation cycling tests were experimentally performed at temperatures below 90 °C. Heat treatment is beneficial to improve the optical absorption capability of MWCNT-H2O nanofluids, and there existed an optimal concentration of about 0.01 wt% with respect to the spectral transmittance and extinction coefficient. Extinction coefficients of MWCNT-H2O nanofluids increased linearly with the MWCNT concentration in a range of 0–0.01 wt% at wavelengths of 500–900 nm. Compared to DI water, the temperature of MWCNT-H2O nanofluid at the optimal mass fraction of 0.01% was increased by about 14.8 °C (or 22.7%) after a light irradiation time of 45 min. The photo-thermal conversion performance was enhanced with increasing the light irradiation cycle at appropriate concentrations of nanofluid, and the probable mechanism caused by the CNT-fiber agglomeration was qualitatively analyzed. The receiver efficiency decreased with increasing the light irradiation time, and the highest value was up to 96.4% at 0.01% mass fraction. The prospects for possible applications of MWCNT-H2O nanofluids in low-temperature direct solar thermal energy absorption were presented.
[en] The study aimed to investigate the incidence of bone uptake of tracer on Tc-99m MIBI imaging and explore its influencing factors and significance for diagnosis of metabolic bone disease (MBD) in patients with hyperparathyroidism (HPT). Seventy-nine consecutive patients with histopathologically confirmed HPT (63 primary and 16 secondary) who had preoperative Tc-99m MIBI imaging were retrospectively evaluated. Serum calcium (Ca), phosphorus (P), and intact parathyroid hormone (iPTH) were measured for all patients, and serum alkaline phosphatase (ALP) was measured for 62 patients. Of the 79 patients, 50 underwent bone mineral density (BMD) examination and 30 underwent bone scintigraphy. The incidence and characteristics of abnormal bone uptake of MIBI were recorded. Mann-Whitney test was performed to determine if serum iPTH, Ca, P, ALP, and BMD were different between the patients with and without MIBI bone uptake. Logistic regression analysis was used to analyze the factors that influence the bone uptake of MIBI. The concordance rate between Tc-99m MIBI imaging and bone scintigraphy in delineating MBD was calculated. Tc-99m MIBI imaging disclosed the abnormal bone uptake of tracer in 22 (27.8%) patients. Of them, 19 showed diffusely increased activity in skeleton, 2 showed focal uptake in brown tumors, and one showed both above patterns. Patients with bone uptake MIBI had higher level of serum iPTH (Z=-4.34, P < 0.001) and ALP (Z=-3.50, P < 0.001) than those without bone uptake. Logistic regression analysis also showed that bone uptake of MIBI was correlated with serum iPTH (OR=4.42, P < 0.001) and ALP (OR=3.21, P=0.002). Among the 30 patients that underwent bone scintigraphy, 76.7% patients showed signs of MBD, and the concordance rate between Tc-99m MIBI imaging and bone scintigraphy was 60% for detecting MBD. Bone uptake of MIBI in patients with HPT is commonly related to a high level of iPTH and ALP; it probably reflects an active stage of MBD, and it should be monitored during the conventional Tc-99m MIBI scintigraphy. (author)
[en] Improvised Nuclear Device (IND) has some characteristics such as ease of manufacture and mass destruction, which attract terrorists to use it in modern cities. Two influences would huge city buildings pose on the effects of IND explosion. One is shielding to its prompt effect, the other is shelter to its fallout. Both of the influences can reduce the range of IND destruction to some extent. On the other hand, casualties may increase because of the intense population in modern big cities. Based on analysis of IND effects and related foreign research, measures of prevention and emergency response on how to reduce casualties in modern city are discussed in this article. (authors)
[en] Extracellular signal-regulated kinases (ERKs) have been implicated to be dispensable for self-renewal of mouse embryonic stem (ES) cells, and simultaneous inhibition of both ERK signaling and glycogen synthase kinase 3 (GSK3) not only allows mouse ES cells to self-renew independent of extracellular stimuli but also enables more efficient derivation of naïve ES cells from mouse and rat strains. Interestingly, some ERKs stay active in mouse ES cells which are maintained in regular medium containing leukemia inhibitory factor (LIF) and bone morphogenetic protein (BMP). Yet, the upstream signaling for ERK activation and their roles in mouse ES cells, other than promoting or priming differentiation, have not been determined. Here we found that mouse ES cells express three forms of Raf kinases, A-Raf, B-Raf, and C-Raf. Knocking-down each single Raf member failed to affect the sustained ERK activity, neither did A-Raf and B-Raf double knockdown or B-Raf and C-Raf double knockdown change it in ES cells. Interestingly, B-Raf and C-Raf double knockdown, not A-Raf and B-Raf knockdown, inhibited the maximal ERK activation induced by LIF, concomitant with the slower growth of ES cells. On the other hand, A-Raf, B-Raf, and C-Raf triple knockdown markedly inhibited both the maximal and sustained ERK activity in ES cells. Moreover, Raf triple knockdown, similar to the treatment of U-0126, an MEK inhibitor, significantly inhibited the survival and proliferation of ES cells, thereby compromising the colony propagation of mouse ES cells. In summary, our data demonstrate that all three Raf members are required for ERK activation in mouse ES cells and are involved in growth and survival of mouse ES cells. - Highlights: ●Mouse ES (mES) cells express all three Raf members, A-Raf, B-Raf, and C-Raf. ●Leukemia inhibitory factor (LIF) temporally activates ERKs in mES cells. ●B-Raf and C-Raf are required for LIF-induced maximal ERKs activity in mES cells. ●All Raf members are required for LIF-induced sustained ERK activity in mES cells. ●All Raf members are required the survival and proliferation of mES cells