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Gain-enabled optical delay readout unit using CMOS-compatible avalanche photodetectors

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Photonics Research 2022年第10期10卷 2422-2433页

作者： RANJAN DAS YANRAN XIE HENRY FRANKIS KERU CHEN HERMANN RUFENACHT GUILLAUME LAMONTAGNE JONATHAN D.B.BRADLEY ANDREW P.KNIGHTS Department of Engineering Physics McMaster UniversityHamiltonOntario L8S 4L7Canada McDonald Detwiler Associates Sainte-Anne-de-BellevueQuebec H9X 3R2Canada

A compact time delay unit is fundamental to integrated photonic circuits with applications in,for example,optical beam-forming networks,photonic equalization,and finite and infinite impulse response optical filtering.In this paper,we report a novel gain-enabled delay readout system using a tunable optical carrier,low-frequency RF signal and CMOS-compatible photodetectors,suitable for silicon photonic integration.The characterization method relies on direct phase measurement of an input RF signal and thereafter extraction of the delay profile.Both integrated silicon and germanium photodetectors coupled with low-bandwidth electronics are used to characterize a microring resonator-based,true-time delay unit under distinct ring–bus coupling formats.The detectors,used in both linear and avalanche mode,are shown to be successful as optical-to-electrical converters and RF amplifiers without introducing significant phase distortion.For a Si–Ge separate-absorption-charge-multiplication avalanche detector,an RF amplification of 10 dB is observed relative to a Ge PIN linear detector.An all-silicon defect-mediated avalanche photodetector is shown to have a 3 dB RF amplification compared to the same PIN detector.All ring delay measurement results are validated by full-wave simulation.Additionally,the impact of photodetector biasing and system linearity is analyzed.

关键词： delay unit optical

COVID-19 and Liver Transplantation:Challenges and Opportunities

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Journal of Clinical and Translational Hepatology 2023年第3期11卷 521-522页

作者： Georgios Tsoulfas Department of Transplantation Surgery Aristotle University School of MedicineThessalonikiGreece

Coronavirus disease 2019(COVID-19)has presented hu-manity with a significant global challenge that has neces-sitated changes and adaptations at all levels.Liver transplant(LT)activity could not have been an exception,as it was impacted both by changes in the urgency of the use of medi-cal resources,including shortage of hospital and intensive care unit beds,problems in outpatient follow-up,redefining the urgency of a LT among others.In addition to the fact that the quarantines placed and the resulting emotional isolation have led to increased alcohol use and abuse.1,2 An effort by several transplant associations and the Centers for Medicare and Medicaid led to issuing guidance and recommendations regarding transplantation surgery during COVID-19.3,4 In the paper“Impact of COVID-19 on Liver Transplant Activity in the USA:Variation by Etiology and Cirrhosis Complications”by Kuo et al.,5 the authors provide us with a thorough evalu-ation of the impact of the COVID-19 pandemic on LT activity based on etiology in the USA,by analysing data from the united Network of Organ Sharing(UNOS)database(2018-2021).The authors looked at two different time periods,one in the pre-COVID era between April 2018 and February 2020.

关键词： Liver alcohol unit

A water-evaporation-induced self-charging hybrid power unit for application in the Internet of Things

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科学通报：英文版 2019年第19期64卷 1409-1417页

作者： Haoxuan He Tianming Zhao Hongye Guan Tianyan Zhong Hui Zeng Lili Xing Yan Zhang Xinyu Xue School of Physics University of Electronic Science and Technology of ChinaChengdu610054China College of Sciences Northeastern UniversityShenyang110819China

A self-charging hybrid power unit has been developed by integrating a water-evaporation-induced nano- generator with a flexible nano-patterned supercapacitor. The nanogenerator can harvest environmental thermal energy and mechanical energy through the water evaporation process, and the supercapacitor can be charged simultaneously. The former offers stable electrical power as output, whereas the Ppy- based supercapacitor shows a capacitance of 12.497 m F/cm^2 with 96.42% retention after 4,000 cycles. After filling the power unit with water as the fuel, it can be fully charged in about 20 min. The power unit can be flexibly integrated with electronic devices such as sensor nodes and wireless transmitters employ- ing the Internet of Things. This new approach can offer new possibilities in continuous future operation of randomly distributed electronic devices incorporated in the Internet of Things.

关键词： Self-charging Hybrid power unit Water evaporation Nanogenerator Supercapacitor Internet of Things

unit Test Data Generation for C Using Rule-Directed Symbolic Execution

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Journal of Computer Science & Technology 2019年第3期34卷 670-689页

作者： Ming-Zhe Zhang Yun-Zhan Gong Ya-Wen Wang Da-Hai Jin State Key Laboratory of Networking and Switching Technology Beijing University of Posts and Telecommunications Beijing 100876China

unit testing is widely used in software development. One important activity in unit testing is automatic test data generation. Constraint-based test data generation is a technique for automatic generation of test data, which uses symbolic execution to generate constraints. unit testing only tests functions instead of the whole program, where individual functions typically have preconditions imposed on their inputs. Conventional symbolic execution cannot detect these preconditions, let alone converting these preconditions into constraints. To overcome these limitations, we propose a novel unit test data generation approach using rule-directed symbolic execution for dealing with functions with missing input preconditions. Rule-directed symbolic execution uses predefined rules to detect preconditions in the individual function, and generates constraints for inputs based on preconditions. We introduce implicit constraints to represent preconditions, and unify implicit constraints and program constraints into integrated constraints. Test data generated based on integrated constraints can explore previously unreachable code and help developers find more functional faults and logical faults. We have implemented our approach in a tool called CTS-IC, and applied it to real-world projects. The experimental results show that rule-directed symbolic execution can find preconditions (implicit constraints) automatically from an individual function. Moreover, the unit test data generated by our approach achieves higher coverage than similar tools and efficiently mitigates missing input preconditions problems in unit testing for individual functions.

关键词： automated unit testing program constraint symbolic execution static analysis

Structural and functional damage to the hippocampal neurovascular unit in diabetes-related depression

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Neural Regeneration Research 2019年第2期14卷 289-297页

作者： Jian Liu Yu-Hong Wang Wei Li Lin Liu Hui Yang Pan Meng Yuan-Shan Han First Hospital of Hunan University of Chinese Medicine Hunan University of Chinese Medicine

Previous studies have shown that models of depression exhibit structural and functional changes to the neurovascular unit. Thus, we hypothesized that diabetes-related depression might be associated with damage to the hippocampal neurovascular unit. To test this hypothesis, neurons, astrocytes and endothelial cells were isolated from the brain tissues of rat embryos and newborn rats. Hippocampal neurovascular unit co-cultures were produced using the Transwell chamber co-culture system. A model of diabetes-related depression was generated by adding 150 mM glucose and 200 μM corticosterone to the culture system and compared with the neuron + astrocyte and astrocyte + endothelial cell co-culture systems. Western blot assay was used to measure levels of structural proteins in the hippocampal neurovascular unit co-culture system. Levels of basic fibroblast growth factor, angiogenic factor 1, glial cell line–derived neurotrophic factor, transforming growth factor β1, leukemia inhibitory factor and 5-hydroxytryptamine in the hippocampal neurovascular unit co-culture system were measured by enzyme-linked immunosorbent assay. Flow cytometry and terminal deoxynucleotidyl transferase(TdT)-mediated dUTP nick end labeling staining was used to assess neuronal apoptosis in the hippocampal neurovascular unit. The neurovascular unit triple cell co-culture system had better barrier function and higher levels of structural and secretory proteins than the double cell co-culture systems. In comparison, in the model of diabetes-related depression, the neurovascular unit was damaged with decreased barrier function, poor structural integrity and impaired secretory function. Moreover, neuronal apoptosis was markedly increased, and 5-hydroxytryptamine levels were reduced. These results suggest that diabetes-related depression is associated with structural and functional damage to the neurovascular unit. Our findings provide a foundation for further studies on the pathogenesis of diabetes-related depression.

关键词： nerve regeneration hippocampus neurovascular unit neurons astrocytes brain microvascular cells cell culture co-culture diabetes-related depression hyperglycemia corticosterone neural regeneration

Hyodeoxycholic acid protects the neurovascular unit against oxygen-glucose deprivation and reoxygenation-induced injury in vitro

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Neural Regeneration Research 2019年第11期14卷 1941-1949页

作者： Chang-Xiang Li Xue-Qian Wang Fa-Feng Cheng Xin Yan Juan Luo Qing-Guo Wang School of Traditional Chinese Medicine Beijing University of Chinese Medicine

Calculus bovis is commonly used for the treatment of stroke in traditional Chinese medicine. Hyodeoxycholic acid(HDCA) is a bioactive compound extracted from calculus bovis. When combined with cholic acid, baicalin and jas-minoidin, HDCA prevents hypoxia-reoxygenation-induced brain injury by suppressing endoplasmic reticulum stress-mediated apoptotic signaling. However, the effects of HDCA in ischemic stroke injury have not yet been studied. Neurovascular unit(NVU) dysfunction occurs in ischemic stroke. Therefore, in this study, we investigated the effects of HDCA on the NVU under ischemic conditions in vitro. We co-cultured primary brain microvascular endothelial cells, neurons and astrocytes using a transwell chamber co-culture system. The NVU was pre-treated with 10.16 or 2.54 μg/mL HDCA for 24 hours before exposure to oxygen-glucose deprivation for 1 hour. The cell counting kit-8 assay was used to detect cell activity. Flow cytometry and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling were used to assess apoptosis. Enzyme-linked immunosorbent assay was used to measure the expression levels of inflammatory cytokines, including interleukin-1β, interleukin-6 and tumor necrosis factor-α, and neurotrophic factors, including brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor. Oxidative stress-related factors, such as superoxide dismutase, nitric oxide, malondialdehyde and γ-glutamyltransferase, were measured using kits. Pretreatment with HDCA significantly decreased blood-brain barrier permeability and neuronal apoptosis, significantly increased transendothelial electrical resistance and γ-glutamyltransferase activity, attenuated oxidative stress damage and the release of inflammatory cytokines, and increased brain-derived neurotrophic factor and glial cell line-derived neurotrophic factor expression. Our findings suggest that HDCA maintains NVU morphological integrity and function by modulating inflammation, oxidation stress, apoptosis, and the expression of neu

关键词： hyodeoxycholic acid oxygen glucose deprivation and reoxygenation blood-brain barrier permeability anti-oxidative anti-inflammatory anti-apoptotic brain-derived neurotrophic factor glial cell line-derived neurotrophic factor ischemic stroke in vitro neurovascular unit

A multi-center cross-sectional study on blood purification among adult patients in intensive care unit in China: a study protocol

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Chinese Medical Journal 2019年第10期132卷 1208-1211页

作者： Yang Gao Zhi-Dong Qi Rui-Jin Liu Hai-Tao Liu Qiu-Yuan Han Xing Zhang Rui Huang Ming Li Zhen-Yu Yang Jun-Bo Zheng Jing-Dong Qu Si-Cong Wang Yan-Song Liu Hong-Liang Wang Kai-Jiang Yu Department of Critical Care Medicine The Second Affiliated Hospital of Harbin Medical University Harbin Heilongjiang 150086 China Department of Critical Care Medicine The Cancer Hospital of Harbin Medical University Harbin Heilongjiang 150081 China Institute of Critical Care Medicine in Sino Russian Medical Research Center of Harbin Medical University Harbin Heilongjiang 150081 China Department of Critical Care Medicine The Rrst Affiliated Hospital of Harbin Medical University Harbin Heilongjiang 150001 China

Background: Blood purification (BP) is one of the most important rescue measures for patients with critical illness in the intensive care unit (ICU), espedally for those with acute kidney injury. The purpose of this nationwide survey was to reveal the real world of current BP practice in different ICUs all over China. This study was designed to be a multi-center cross-sectional study. Methods: All adult patients (over 18 years of age), who were admitted to ICU and required BP in 35 sub-centers across China were included during 30-day survey period in 2018. Demographic characteristics and clinical data were recorded including the timing of treatment initiation, indications, modality, relative contraindication, establishment of vascular access, selection of filter/membrane, settings, anti-coagulation, executive department, complication, intake, and output. Discussion: This nationwide survey may contribute to reveal the real world of current BP practice in different ICUs all over China.

关键词： Blood purification Acute kidney injury Intensive care unit Adult China

A new building block with intramolecular D-A character for conjugated polymers: ladder structure based on B←N unit

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Science China Chemistry 2019年第10期62卷 1387-1392页

作者： Xingxin Shao Chuandong Dou Jun Liu Lixiang Wang State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China University of Science and Technology of China School of Applied Chemistry and EngineeringHefei 230026China

The general strategy to construct D-A type conjugated polymers is alternating copolymerization of electron-donating(D)monomer and electron-accepting(A)monomer.In this article,we report a new strategy to develop D-A type conjugated polymers,i.***.first fuse the D and A units into a polycyclic structure to produce a building block and then polymerize the building block with another unit.We develop a new building block with ladder structure based on B←N unit,B←N bridged dipyridylbenzene(BNDPB).In the skeleton of BNDPB,one diamine-substituted phenylene ring(D unit)and two B←N-linked pyridyl rings(A unit)are fused together to produce the polycyclic structure.Owning to the presence of intramolecular D-A character,the building block itself exhibits narrow bandgap of 1.74 eV.The conjugated polymers based on BNDPB show unique electronic structures,i.***.localized HOMOs and delocalized LUMOs,which are rarely observed for conventional D-A conjugated polymers.The polymers exhibit smaller bandgap than that of the building block BNDPB and display near-infrared(NIR)light absorption(λabs=ca.700 nm).This study thus provides not only a new strategy to design D-A conjugated polymers but also a new kind of building block with narrow bandgap.

关键词： D-A character conjugated polymers building block ladder structure B-N unit

Diagonal-symmetrical and Midline-symmetrical unit Cells with Same Porosity for Bone Implant: Mechanical Properties Evaluation

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Journal of Bionic Engineering 2019年第3期16卷 468-479页

作者： Jian Li Diansheng Chen Yingying Zhang Yan Yao Zhongjun Mo Lizhen Wang Yubo Fan Robotic Institute Beihang University Beijing 100191 China Beijing Key Laboratory of Rehabilitation Technical Aids for Old-Age and Disability and Key Laboratory of Rehabilitation Aids Technology and System of the Ministry of Civil Affairs National Research Center for Rehabilitation Technical Aids Beijing 100176 China Beijing Advanced Innovation Center for Biomedical Engineering Beihang University Beijing 100191 China Key Laboratory for Biomechanics and Mechanobiology of Ministry of Education School of Biological Science and Medical Engineering Beihang University Beijing 100191 China

In this study, mechanical properties of bionic porous structures with diagonal-symmetrical and midline-symmetrical unit cells were studied when the porosities were same. Three typical unit cells (Diamond (DO), Rhombic Dodecahedron (RD), and Octet Truss (OT)) were selected, in which DO has diagonal-symmetrical shape, while RD and OT share midline-symmetrical structure. Based on the same porosity, corresponding models were designed, and Ti6Al4V samples were manufactured by electron beam melting. Then, using Mechanical Properties Testing (MPT) and Finite Element Analysis (FEA) methodologies, mechanical properties and transmissions of different porous structures were evaluated. Besides, composition and details before and after printing were analyzed with Energy Dispersive Spectrometer (EDS), X-ray diffraction (XRD) and Scanning Electron Microscope (SEM). MPT results showed that midline-symmetrical shape would have superior compressive performance than diagonal-symmetrical shape, but opposite trend for the torsion performance, which were in line with FEA prediction. Furthermore, effective modulus of DO, RD and OT were 2.59 GPa, 4.89 GPa, and 1.77 GPa, approximating the mechanical properties of human bones. Additionally, manufacturing defects and discrepancies between FEA and MPT were found. This study would provide great helps for unit cell selection and initial mechanical properties matching for optimum bone implants.

关键词： bionic design porous implant mechanical properties unit cell additive manufacturing 3D printing