158 research outputs found
The Economics of Municipal Solid Waste Management
为减轻大量禽畜废弃物对环境的污染,将其资源化为优质的无害化有机肥料,研究了微生物F468对降低鸡粪N营养元素损失和促进其无害化进程的影响。结果表明,继代80次,F468降低鸡粪氨气挥发的能力无显著变化,能降低鸡粪79%的N元素损失。F468还能通过降低蛔虫卵和粪肠杆菌的数量,促进鸡粪的无害化进程。不添加F468,蛔虫卵和粪肠杆菌达到我国无害化标准(NY884-2004)的时间分别需要25d和20d。加入F468后,蛔虫卵和粪肠杆菌达到我国无害化标准的时间分别需要15d和10d,均比不加微生物提前10d达到我国无害化标准
The study of the feasibility of segmental bone defect repair with tissue- engineered bone membrane: a qualitative observation
The objective of the study was to investigate the feasibility of intramembranous osteogenesis from tissue-engineered bone membrane in vivo. Bone marrow mesenchymal stem cells (MSCs) of rabbits were harvested, expanded and some of them were induced into osteoblasts. Porcine small intestinal submucosa (SIS) was converted by a series of physical and chemical procedures into a scaffold. MSCs and induced osteoblasts were seeded separately onto the scaffold, thus fabricating two kinds of tissue-engineered bone membrane. A total of 12 New Zealand rabbits were subjected to a surgical operation; a 15 mm bone segment, including the periosteum, was resected from the radius on both sides of each rabbit to create critical bone defects. The two kinds of tissue-engineered bone membrane and SIS (as control) were implanted randomly into the site of bone defect. The animals had radiographs and were killed after 4 weeks. The specimens were harvested and histological examination performed for evidence of osteogenesis. Bone tissue had formed in defects treated by the two kinds of tissue-engineered bone membrane at 4 weeks. This was supported by the X-ray and histological examination, which confirmed the segmental gap bridged by bone. There was no attempt to bridge in the bone defect treated by SIS. Tissue-engineered bone membrane, constructed by seeding allogeneic cells on an xenogeneic and bio-derived scaffold, can repair critical bone defects successfully
Experiment and simulation research on sound insulation performance of magnesium alloy dash panel
The finite element model of dash panel was built and its reliability was then verified by the comparison between the simulation and the experimental results. Subsequently, FE-SEA simulation model of dash panel was built and then compared with the structure-acoustic coupling method as well as the experimental results. As a result, the superiority and reliability of FE-SEA method for predicting the sound insulation performance of dash panel are shown. In addition, the sound insulation performance of the original steel dash panel was also calculated and compared with magnesium alloy dash panel, and the results show that the sound insulation performance of magnesium alloy dash panel has reached the level of steel dash panel. The mentioned analysis shows that magnesium alloy material has a low noise characteristic and it can also achieve light-weight. Then, sound package was applied to dash panel to calculate its sound insulation performance, and the results are found that sound insulation performance is not significantly improved at low-frequency range. Reversely, it will be reduced with increasing of sound package thickness. However, improvement of sound insulation performance is very obvious at high frequency range. In order to evaluate the comprehensive performance in terms of noise reduction and lightweight, noise reduction efficiency was proposed and calculated. This research does also provide a reference for the acoustic design of magnesium alloy components
Degradation of Toxic Organic Contaminants by Graphene Cathode in an Electro‐Fenton System
A novel composite electrode was constructed by pressing graphene and CuO, using a cathode in an electro‐Fenton (EF) system. Cyclic voltammetry, charge/discharge curve and electrochemical impedance spectroscopy (EIS) were used to characterize the composite electrode. The degradation of a toxic organic contaminant, Terramycin, by EF system was studied in an undivided electrolysis cell. The possible degradation products of Terramycin were studied by a Fourier transform‐infrared spectrum, and the findings showed that the structure of Terramycin was damaged. The variations of hydrogen peroxide and the relative content of hydroxyl radical (.OH) during the degradation process were traced by enzyme catalysis method and fluorescence spectrometry. The results showed that the electro‐catalytic degradation of Terramycin occurred by an ·OH radical mechanism. More importantly, this as‐prepared cathode was very stable and could be reused without any catalytic activity decrease, suggesting its potential application in the wastewater treatment
Live Cells Exert 3-Dimensional Traction Forces on Their Substrata
The traction forces exerted by an adherent cell on a substrate have been studied only in the two-dimensions (2D) tangential to substrate surface (Txy). We developed a novel technique to measure the three-dimensional (3D) traction forces exerted by live bovine aortic endothelial cells (BAECs) on polyacrylamide deformable substrate. On 3D images acquired by confocal microscopy, displacements were determined with image-processing programs, and traction forces in tangential (XY) and normal (Z) directions were computed by finite element method (FEM). BAECs generated traction force in normal direction (Tz) with an order of magnitude comparable to Txy. Tz is upward at the cell edge and downward under the nucleus, changing continuously with a sign reversal between cell edge and nucleus edge. The method was evaluated regarding accuracy and precision of displacement measurements, effects of FE mesh size, displacement noises, and simple bootstrapping. These results provide new insights into cell-matrix interactions in terms of spatial and temporal variations in traction forces in 3D. This technique can be applied to study live cells to assess their biomechanical dynamics in conjunction with biochemical and functional activities, for investigating cellular functions in health and disease
Extraction Method of Driver’s Mental Component Based on Empirical Mode Decomposition and Approximate Entropy Statistic Characteristic in Vehicle Running State
In the driver fatigue monitoring technology, the essence is to capture and analyze the driver behavior information, such as eyes, face, heart, and EEG activity during driving. However, ECG and EEG monitoring are limited by the installation electrodes and are not commercially available. The most common fatigue detection method is the analysis of driver behavior, that is, to determine whether the driver is tired by recording and analyzing the behavior characteristics of steering wheel and brake. The driver usually adjusts his or her actions based on the observed road conditions. Obviously the road path information is directly contained in the vehicle driving state; if you want to judge the driver’s driving behavior by vehicle driving status information, the first task is to remove the road information from the vehicle driving state data. Therefore, this paper proposes an effective intrinsic mode function selection method for the approximate entropy of empirical mode decomposition considering the characteristics of the frequency distribution of road and vehicle information and the unsteady and nonlinear characteristics of the driver closed-loop driving system in vehicle driving state data. The objective is to extract the effective component of the driving behavior information and to weaken the road information component. Finally the effectiveness of the proposed method is verified by simulating driving experiments
Erythrocyte transfusion limits the role of elevated red cell distribution width on predicting cardiac surgery associated acute kidney injury
Background: Acute kidney injury (AKI) is one of the more serious complications after cardiac surgery. Elevated red cell distribution width (RDW) was reported as a predictor for cardiac surgery associated acute kidney injury (CSAKI). However, the increment of RDW by erythrocyte transfusion makes its prognostic role doubtful. The aim of this study is to elucidate the impact of erythrocyte transfusion on the prognostic role of elevated RDW for predicting CSAKI.Methods: A total of 3207 eligible patients who underwent cardiac surgery during 2016–2017 were enrolled. Changes of RDW was defined as the difference between preoperative RDW and RDW measured 24 h after cardiac surgery. The primary outcome was CSAKI which was defined by the Kidney Disease: Improving Global Outcomes Definition and Staging (KDIGO) criteria. Univariate and multivariate analysis were performed to identify predictors for CSAKI.Results: The incidence of CSAKI was 38.07% and the mortality was 1.18%. CSAKI patients had higher elevated RDW than those without CSAKI (0.65% vs. 0.39%, p < 0.001). Multivariate regression showed that male, age, New York Heat Association classification 3–4, elevated RDW, estimated glomerular filtration rate < 60 mL/min/1.73 m2, cardiopulmonary bypass time > 120 min and erythrocyte transfusion were associated with CSAKI. Subgroup analysis showed elevated RDW was an independent predictor for CSAKI in the non-transfused subset (adjusted odds ratio: 1.616, p < 0.001) whereas no significant association between elevated RDW and CSAKI was found in the transfused patients (odds ratio: 1.040, p = 0.497).Conclusions: Elevated RDW is one of the independent predictors of CSAKI in the absence of erythrocyte transfusion, which limits the prognostic role of the former on predicting CSAKI
(E)-1-[2-Hydroxy-4,6-bis(methoxymethoxy)phenyl]-3-[3-methoxy-4-(methoxymethoxy)phenyl]prop-2-en-1-one
The title compound, C22H26O9, crystallizes with two independent molecules in the asymmetric unit in which the dihedral angles between the two benzene rings are 21.4 (2) and 5.1 (2)°. An intramolecular O—H⋯O hydrogen bond occurs in each molecule. Intermolecular C—H⋯O hydrogen bonds stabilize the crystal structure
New paleomagnetic constraints on the Cretaceous tectonic framework of the Antarctic Peninsula
Understanding the tectonic framework of the Antarctic Peninsula is hindered by a paucity of paleomagnetic data from key locations. In this study, we present paleomagnetic data from the South Shetland Islands, to the northwest of the Antarctic Peninsula, which provides valuable paleoposition constraints on the Western domain of the Antarctic Peninsula. We report a key reliable paleopole (58.1°S, 354.3°E, A95=6.3°) from Livingston Island in the South Shetland Islands at ∼102 Ma. Plate reconstruction models from the Early Cretaceous attach the South Shetland Islands to the Pacific margin of southern Patagonia-Fuegian Andes at ∼140 Ma. The South Shetland Islands then experienced southward translation to its current position to the northwest of the Antarctic Peninsula following counterclockwise rotation during ∼100-90 Ma. A similar counterclockwise rotation has also been identified from southern Patagonia-Fuegian Andes but is absent in the Antarctic Peninsula, suggesting a direct affinity between the South Shetland Islands and southern Patagonia-Fuegian Andes. However, the consistent, almost northward Cretaceous paleomagnetic declination in the Antarctic Peninsula, and the near-synchronous tectonic-magmatic history between the Antarctic Peninsula and the southern Patagonia-Fuegian Andes support an autochthonous continental subduction model for most of the Antarctic Peninsula
Clinical features of COVID-19-related optic neuritis: a retrospective study
ObjectiveThis retrospective study aimed to investigate the clinical features of optic neuritis associated with COVID-19 (COVID-19 ON), comparing them with neuromyelitis optica-associated optic neuritis (NMO-ON), myelin oligodendrocyte glycoprotein-associated optic neuritis (MOG-ON), and antibody-negative optic neuritis (antibody-negative ON).MethodsData from 117 patients (145 eyes) with optic neuritis at the Shantou International Eye Center (March 2020–June 2023) were categorized into four groups based on etiology: Group 1 (neuromyelitis optica-related optic neuritis, NMO-ON), Group 2 (myelin oligodendrocyte glycoprotein optic neuritis, MOG-ON), Group 3 (antibody-negative optic neuritis, antibody-negative ON), and Group 4 (optic neuritis associated with COVID-19, COVID-19 ON). Characteristics of T2 and enhancement in orbital magnetic resonance imaging (MRI) were assessed. Best-corrected visual acuity (BCVA) was compared before treatment, at a short-term follow-up (14 days), and at the last follow-up after treatment.ResultsThe COVID-19-associated optic neuritis (COVID-19 ON) group exhibited 100% bilateral involvement, significantly surpassing other groups (P < 0.001). Optic disk edema was observed in 100% of COVID-19 ON cases, markedly differing from neuromyelitis optica-related optic neuritis (NMO-ON) (P = 0.023). Orbital magnetic resonance imaging (MRI) revealed distinctive long-segment lesions without intracranial involvement in T1-enhanced sequences for the COVID-19 ON group compared to the other three groups (P < 0.001). Discrepancies in optic nerve sheath involvement were noted between the COVID-19 ON group and both NMO-ON and antibody-negative optic neuritis (antibody-negative ON) groups (P = 0.028). Before treatment, no significant difference in best-corrected visual acuity (BCVA) existed between the COVID-19 ON group and other groups. At the 14-day follow-up, BCVA in the COVID-19 ON group outperformed the NMO-ON (P < 0.001) and antibody-negative ON (P = 0.028) groups, with no significant difference observed compared to the myelin oligodendrocyte glycoprotein optic neuritis (MOG-ON) group. At the last follow-up after treatment, BCVA in the COVID-19 ON group significantly differed from the NMO-ON group (P < 0.001).ConclusionOptic neuritis associated with COVID-19 (COVID-19 ON) predominantly presents with bilateral onset and optic disk edema. Orbital magnetic resonance imaging (MRI) demonstrates that COVID-19 ON presents as long-segment enhancement without the involvement of the intracranial segment of the optic nerve in T1-enhanced images. Glucocorticoid therapy showed positive outcomes
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