NMR studies of gas and water adsorption in carbon based materials

In this dissertation, we used 1H NMR to study the gas and water adsorption in carbon based materials. The NMR studies indicated that at room temperature, the interior of cap-opened Single Wall Nanotubes (SWNTs) becomes available for methane and ethane adsorption. The endohedral adsorption is the dominant mechanism when pressure is lower than 1Mpa. The adsorptions follow Langmuir adsorption isotherm with related adsorption energy of 22.7 KJ/mol for methane and 29.2 KJ/mol for ethane. The average exchange time between molecules adsorbed inside SWNTs and free gas molecules outside is on the order of 80ms. It is shown that exposure to oxygen has no effect on methane and ethane endohedral adsorption, which suggests smaller adsorption energy of oxygen compared to that of methane and ethane. In the study of the water adsorption in SWNTs at room temperature, the adsorption isotherm from 1H NMR spectrum indicated clear hysteresis loop. Quantitative analysis gave the adsorption amount of 3 mmol/g in SWNTs at saturated vapor, which was considerably lower compared to 14 mmol/g of bulk liquid water. Combined with T2 analysis, we believed that the state of adsorped water in SWNTs is in between vapor and bulk liquid. The primary adsorption sites are associated with tube ends and defects, which have strong effects on water adsorption. The study of adsorption of hydrogen in Boron doped graphite and Boron doped SWNTs proved considerable increment of adsorption energy at moderately high pressure and room temperature, which may lead to a new method for improving hydrogen storage at room temperature

Pre‐symptomatic transmission of novel coronavirus in community settings

We used contact tracing to document how COVID‐19 was transmitted across 5 generations involving 10 cases, starting with an individual who became ill on January 27. We calculated the incubation period of the cases as the interval between infection and development of symptoms. The median incubation period was 6.0 days (interquartile range, 3.5‐9.5 days). The last two generations were infected in public places, 3 and 4 days prior to the onset of illness in their infectors. Both had certain underlying conditions and comorbidity. Further identification of how individuals transmit prior to being symptomatic will have important consequences.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163478/2/irv12773.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163478/1/irv12773_am.pd

Secure State Estimation of DC Microgrid System Under False Data Injection Attack

In DC microgrids, distributed secondary control plays an important role in maintaining power distribution and voltage recovery. However, distributed control architecture is vulnerable to external attacks, especially false data injection (FDI) attacks. To solve the problem of the controller being attacked, a distributed Kalman filter is proposed to estimate the attack signals and states. In addition, a compensation mechanism is adopted to defend against attacks and improve system resilience. Finally, the effectiveness of the proposed method is verified in the scenario of time-varying attack and load switching. The results show that the proposed method can effectively suppress potential external attacks and ensure the system’s stability

Unification of rheology of thixotropic yield stress fluids and screen printing properties of pastes

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Comparative geochemical study of scheelite from the Shizhuyuan and Xianglushan tungsten skarn deposits, South China: Implications for scheelite mineralization

Scheelite has been analyzed from the Shizhuyuan and the Xianglushan world-class W deposits from the Nanling W–Sn region and Jiangnan W belt, respectively. The Shizhuyuan deposit consists of proximal skarn and greisen W–Sn–Mo–Bi and distal Pb–Zn–Ag veins. The Xianglushan deposit, contains layer-like sulfide–scheelite and skarn W orebodies on granite cupolas overprinted by W greisen veins. Scheelite in skarn ores from the Shizhuyuan contains higher concentrations of Mo than those in the sulfide–scheelite and skarn ores from the Xianglushan deposit, reflecting differences between oxidizing and reducing magmatic-hydrothermal fluids. Under oxidizing conditions, W is accompanied by Mo partitions into exsolved fluids to form W–Mo garnet skarns, whereas under reducing conditions, little Mo is carried by exsolved fluids to form W pyroxene skarns. Trace element patterns of scheelite from both deposits show negative Ba, Sr, Zr, and Ti, and positive Ta anomalies. Rare earth element (REE) patterns of scheelite within skarns from the Shizhuyuan deposit have negatively inclined and flat M-type tetrad patterns, and scheelite from the greisens displays flat and positively inclined M-type tetrad patterns. We infer that the fluids formed scheelite within the W skarns and greisens inherited parental magma trace element and REE characteristics (depleted Ba, Sr, Zr, and Ti, enriched Ta, negative Eu anomalies, and tetrad effects). Whereas, scheelite from sulfide–scheelite veins and skarns of the Xianglushan deposit also has W- and MW-type tetrad REE patterns. The W-type tetrad REE patterns are complementary to REE patterns from the Renjiashan granite, and the MW-type tetrad REE patterns occur during a single evolutionary stage within a complex hydrothermal environment. Sulfide mineralization can form after or before W skarns (the former like Shizhuyuan deposit and the latter like Xianglushan deposit). The formation conditions of the latter included reducing conditions and sulfide firstly supersaturated in the melt, resulting in sulfide drops which carried W aggregated on the cupolas. W skarns and greisens in both deposits underwent generally successive processes related to water supersaturation in the melt. Following a temperature decrease and crystallization, bubbles carried material changing from Si and metal to Si oxide complexes.This work was supported by the National Natural Science Foundation of China (Nos. 41430314 and 41303034), National Nonprofit Institute Research Grant of Chinese Academy of Geological Sciences (Nos. K1617 and JYYWF20180601), and National Key R&D Plan (2016YFC0600408)

Geology and molybdenite Re–Os age of the Dahutang granite-related veinlets-disseminated tungsten ore field in the Jiangxin Province, China

This is a brief research report about the recently-discovered and currently being explored Dahutang tungsten deposit (or ore field) in northwestern Jiangxi, south-central China. The deposit is located south of the Middle–Lower Yangtze River valley Cu–Au–Mo–Fe porphyry–skarn belt (YRB). The mineralization is genetically associated with Cretaceous porphyritic biotite granite and fine-grained biotite granite and is mainly hosted within a Neoproterozoic biotite granodiorite batholith. The Dahutang ore field comprises veinlets-disseminated (~ 95% of the total reserve), breccia (~ 4%) and wolframite–scheelite quartz vein (~ 1%) ore styles. The mineralization and alteration are close to the pegmatite shell between the Cretaceous porphyritic biotite granite and Neoproterozoic biotite granodiorite and the three styles of ore bodies mentioned above are related to zoned hydrothermal alteration that includes greisenization, K-feldspar alteration, silicification, carbonatization, chloritization and fluoritization arranged in time (early to late) and space (bottom to top). Five samples of molybdenite from the three types of ores have been collected for Re/Os dating. The results show Re/Os model ages ranging from 138.4 Ma to 143.8 Ma, with an isochron age of 139.18 ± 0.97 Ma (MSWD = 2.9). The quite low Re content in molybdenite falls between 0.5 ppm and 7.8 ppm that is indicative of the upper crustal source. This is quite different from molybdenites in the YRB Cu–Au–Mo–Fe porphyry–skarn deposits that contain between 53 ppm and 1169 ppm Re, indicating a mantle source. The Dahutang tungsten system is sub-parallel with the YRB porphyry–skarn Cu–Au–Mo–Fe system. Both are situated in the north margin of the Yangtze Craton and have a close spatial–temporal relationship. This possibly indicates a comparable tectonic setting but different metal sources. Both systems are related to subduction of the Paleo-Pacific plate beneath the Eurasian continent in Early Cretaceous. The Cu–Au–Mo–Fe porphyry–skarn ores are believed genetically related to granitoids derived from the subducting slab, whereas the porphyry W deposits are associated with S-type granitoids produced by remelting of the upper crust by heat from upwelling asthenoshere

Ureteral reconstruction using a tapered non-vascularized bladder graft: an experimental study in a canine animal model

Abstract Background Reconstruction of ureteral defects and strictures remains problematic for urologists. We aimed to investigate the possibility of a tapered non-vascularized bladder graft as a novel substitute for ureteral reconstruction. Methods This experimental study was conducted on nine beagles. Under general anesthesia, a full-thickness graft with 5–6 cm in length was disassociated from the anterior upper wall of the bladder, and tapered into 1/3 to 1/2 thickness, remaining the urothelial surface. After removal of 5 cm of right-sided mid-ureter, the tapered bladder graft was tubularized along the long axis and then respectively anastomosed to the upper and lower stumps of the ureter. A retrograde urography through a cystostomy was performed 8 weeks after the ureteral reconstruction. The animals were euthanized, and histopathologic examinations of the neoureters were performed. Results There were no severe complications during postoperative follow-up. The urography indicated patent urine excretion and no fistula or stenosis. Histopathologic examinations of the neoureters showed open lumen with urothelial lining. Nutrient vessels were observed in healthy submucosa, lamina muscularis and peripheral connective tissue. Conclusions Our study implied that ureteral reconstruction by a tapered non-vascularized bladder graft was anatomically possible in our animal model. Further studies are expected to confirm long-term and functional outcomes

Liquid Hybridization and Solid Phase Detection: A Highly Sensitive and Accurate Strategy for MicroRNA Detection in Plants and Animals

MicroRNAs (miRNAs) play important roles in nearly every aspect of biology, including physiological, biochemical, developmental and pathological processes. Therefore, a highly sensitive and accurate method of detection of miRNAs has great potential in research on theory and application, such as the clinical approach to medicine, animal and plant production, as well as stress response. Here, we report a strategic method to detect miRNAs from multicellular organisms, which mainly includes liquid hybridization and solid phase detection (LHSPD); it has been verified in various species and is much more sensitive than traditional biotin-labeled Northern blots. By using this strategy and chemiluminescent detection with digoxigenin (DIG)-labeled or biotin-labeled oligonucleotide probes, as low as 0.01–0.25 fmol [for DIG-CDP Star (disodium2-chloro-5-(4-methoxyspiro{1,2-dioxetane-3,2′-(5′-chloro)tricyclo[3.3.1.13,7]decan}-4-yl)phenyl phosphate) system], 0.005–0.1 fmol (for biotin-CDP Star system), or 0.05–0.5 fmol (for biotin-luminol system) of miRNA can be detected and one-base difference can be distinguished between miRNA sequences. Moreover, LHSPD performed very well in the quantitative analysis of miRNAs, and the whole process can be completed within about 9 h. The strategy of LHSPD provides an effective solution for rapid, accurate, and sensitive detection and quantitative analysis of miRNAs in plants and animals

Effect of ultrasound-guided transversus abdominis plane block in reducing atelectasis after laparoscopic surgery in children: A randomized clinical trial

Background: Atelectasis is a commonly observed postoperative complication of general anesthesia in children. Pulmonary protective ventilation strategies have been reported to have a beneficial effect on postoperative atelectasis in children. Therefore, the present study aimed to evaluate the efficacy of the ultrasound-guided transversus abdominis plane (TAP) block technique in preventing the incidence of postoperative atelectasis in children. Materials and methods: This study enrolled 100 consecutive children undergoing elective laparoscopic bilateral hernia repair and randomly divided them into the control and TAP groups. Conventional lung-protective ventilation was initiated in both groups after the induction of general anesthesia. The children in the TAP group received an ultrasound-guided TAP block with 0.3 mL/kg of 0.5% ropivacaine after the induction of anesthesia. Results: Anesthesia-induced atelectasis was observed in 24% and 84% of patients in the TAP (n = 50) and control (n = 50) groups, respectively, before discharge from the post-anesthetic care unit (T3; PACU) (odds ratio [OR], 0.062; 95% confidence interval [CI], 0.019–0.179; P < 0.001). No significant difference was observed between the control and TAP groups in terms of the lung ultrasonography (LUS) scores 5 min after endotracheal intubation (T1). However, the LUS scores were lower in the TAP group than those in the control group at the end of surgery (T2, P < 0.01) and before discharge from the PACU (T3, P < 0.001). Moreover, the ace, legs, activity, cry and consolability (FLACC) pain scores in the TAP group were lower than those in the control group at each postoperative time point. Conclusion: Ultrasound-guided TAP block effectively reduced the incidence of postoperative atelectasis and alleviated pain in children undergoing laparoscopic surgery