Investigation of a Resistive-Gate MESFET Contiguous Domain Oscillator

The goal of this research is to investigate a novel microwave oscillator — the MESFET version contiguous domain oscillator. By combining the transferred electron effect in GaAs material with the two dimensional electrostatics in the device, a series of contiguous electron packets can be generated in the channel of a resistive gate MESFET. Therefore this novel device can eliminate some restraints which are suffered by the presently existing oscillators, and provides unique new features for oscillators: a wide range of oscillation frequency (from a few tens of GHz to a hundred GHz), an ideal current source, instantaneous frequency tuning, compatibility with the presently existing planar semiconductor integration technology, etc. This investigation is composed of two parts. The first pa rt is to use various semiconductor processing technologies to fabricate the devices which can supply an ideal electrostatic condition for the electrons in the channel; the second part is the device characterization; which includes power output, frequency tunability, and the relationship between device performance and device parameters

Comparative Approaches in Managing Wetland Environments and Land Uses: Rainbow Lake in Michigan, Guangzhou City in China, and Chinese Sponge Concept Case Studies

Environmental scientists, natural resources agencies, planners, landscape architects, engineers, and concerned citizens are interested in the impacts that land uses within watersheds have upon lake water quality and water runoff volume. For the past 40 years, much has been discovered and many North American water bodies from small to large can be reliably modeled and studied, employing phosphorus as the identifier of water quality. We present an overview of the key features in this multi-disciplinary effort and illustrate how to apply the general method to Rainbow Lake, in Gratiot County, Michigan, the USA. In addition, we illustrate how these fundamental ideas are being employed at the Haizhu wetland park, a large wetland setting in Guangzhou, the People’s Republic of China, and present Chinese planning and design efforts termed “sponge city” to address new ideas to reduce runoff and improve water quality

Weight-Constrained Reliability Allocation for All Electric Aircraft Powertrains

The shift towards electric aircraft poses significant challenges in balancing lightweight design and high reliability of powertrains. Typically, improving reliability requires redundancy, which adds weight, while lightweight designs often compromise reliability. In this paper, we propose a weight-constrained reliability allocation model for the powertrain design of electric aircraft. The relationship between reliability and weight for each component, including battery, inverter, and electric motor is analytically and linearly expressed using universal generating functions (UGF) and McCormick envelope technique. Our model considers variable operating conditions that impact component reliability, such as changes in core temperature caused by high-attitude and variable thrust power caused by wind speed and direction. Our approach enhances the overall performance of electric powertrains systems for aircraft. Using the " Spirit of Innovation " electric aircraft as a case study, the proposed method can improve the powertrain reliability from 0.9786 to 0.9870 through reasonable allocation without adding extra weight. Alternatively, it can reduce the weight by 3.1% without compromising the reliability of the powertrain.</p

Examining the impact of perceived stress, anxiety, and resilience on depression among medical staff after COVID-19 quarantine: a chain mediation analysis

IntroductionThe COVID-19 pandemic and subsequent quarantine measures have led to a significant impact on mental health worldwide. Medical staff, in particular, have been exposed to high levels of stress due to their frontline work during the crisis. However, there is still limited research on the psychological mechanism among medical staff after quarantine.MethodsIn this cross-sectional observational study, 150 medical staff from Shanghai YangZhi Rehabilitation Hospital, Shanghai, China, were enrolled in October 2022. SPSS 26.0 and PROCESS 4.0 model 6 were used to analyze the chain mediating effect of perceived stress, anxiety, resilience and depression among medical staff after quarantine. Anxiety and depression were compared during and after the quarantine. All scales have high validity and reliability in a Chinese population.ResultsOur findings revealed a positive correlation between perceived stress and anxiety (r = 0.60, p &lt; 0.001) and depression (r = 0.60, p &lt; 0.001) levels among medical staff. Conversely, resilience was found to have a negative correlation with perceived stress (r = −0.67, p &lt; 0.001), anxiety (r = −0.57, p &lt; 0.001) and depression (r = −0.61, p &lt; 0.001). The score of depression during the quarantine was higher than the score after the quarantine, but the p-value is only marginally significant (p = 0.067). The score of anxiety during the quarantine was significantly higher than the score after the quarantine (p &lt; 0.05). Moreover, the chain mediation model suggested that anxiety and resilience could mediate the association between perceived stress and depression among medical staff following quarantine. Specifically, perceived stress had no direct effect on depression (β = 0.025, t = 0.548, p = 0.59) but positively predicted anxiety (β = 0.381, t = 8.817, p &lt; 0.001) and resilience (β = −1.302, t = −6.781, p &lt; 0.001), which influenced depression levels indirectly through multiple pathways. The three indirect paths: the mediating role of anxiety, the mediating role of resilience, and the chain mediating role of both anxiety and resilience.DiscussionThis study emphasizes the importance of psychological interventions aimed at protecting medical staff’s psychological resilience and promoting coping mechanisms to manage stress during and after crises such as the COVID-19 pandemic. Additionally, our findings suggest that both anxiety and resilience play critical roles in mitigating the detrimental effects of perceived stress on mental health and further highlight the need for continued research to better understand the complex interplay of these factors

Estimation of affinities of ligands in mixtures via magnetic recovery of target-ligand complexes and chromatographic analyses: chemometrics and an experimental model

<p>Abstract</p> <p>Background</p> <p>The combinatorial library strategy of using multiple candidate ligands in mixtures as library members is ideal in terms of cost and efficiency, but needs special screening methods to estimate the affinities of candidate ligands in such mixtures. Herein, a new method to screen candidate ligands present in unknown molar quantities in mixtures was investigated.</p> <p>Results</p> <p>The proposed method involves preparing a processed-mixture-for-screening (PMFS) with each mixture sample and an exogenous reference ligand, initiating competitive binding among ligands from the PMFS to a target immobilized on magnetic particles, recovering target-ligand complexes in equilibrium by magnetic force, extracting and concentrating bound ligands, and analyzing ligands in the PMFS and the concentrated extract by chromatography. The relative affinity of each candidate ligand to its reference ligand is estimated <it>via </it>an approximation equation assuming (a) the candidate ligand and its reference ligand bind to the same site(s) on the target, (b) their chromatographic peak areas are over five times their intercepts of linear response but within their linear ranges, (c) their binding ratios are below 10%. These prerequisites are met by optimizing primarily the quantity of the target used and the PMFS composition ratio.</p> <p>The new method was tested using the competitive binding of biotin derivatives from mixtures to streptavidin immobilized on magnetic particles as a model. Each mixture sample containing a limited number of candidate biotin derivatives with moderate differences in their molar quantities were prepared <it>via </it>parallel-combinatorial-synthesis (PCS) without purification, or <it>via </it>the pooling of individual compounds. Some purified biotin derivatives were used as reference ligands. This method showed resistance to variations in chromatographic quantification sensitivity and concentration ratios; optimized conditions to validate the approximation equation could be applied to different mixture samples. Relative affinities of candidate biotin derivatives with unknown molar quantities in each mixture sample were consistent with those estimated by a homogenous method using their purified counterparts as samples.</p> <p>Conclusions</p> <p>This new method is robust and effective for each mixture possessing a limited number of candidate ligands whose molar quantities have moderate differences, and its integration with PCS has promise to routinely practice the mixture-based library strategy.</p

Molecular analysis of phosphomannomutase (PMM) genes reveals a unique PMM duplication event in diverse Triticeae species and the main PMM isozymes in bread wheat tissues

BACKGROUND: Phosphomannomutase (PMM) is an essential enzyme in eukaryotes. However, little is known about PMM gene and function in crop plants. Here, we report molecular evolutionary and biochemical analysis of PMM genes in bread wheat and related Triticeae species. RESULTS: Two sets of homoeologous PMM genes (TaPMM-1 and 2) were found in bread wheat, and two corresponding PMM genes were identified in the diploid progenitors of bread wheat and many other diploid Triticeae species. The duplication event yielding PMM-1 and 2 occurred before the radiation of diploid Triticeae genomes. The PMM gene family in wheat and relatives may evolve largely under purifying selection. Among the six TaPMM genes, the transcript levels of PMM-1 members were comparatively high and their recombinant proteins were all enzymatically active. However, PMM-2 homoeologs exhibited lower transcript levels, two of which were also inactive. TaPMM-A1, B1 and D1 were probably the main active isozymes in bread wheat tissues. The three isozymes differed from their counterparts in barley and Brachypodium distachyon in being more tolerant to elevated test temperatures. CONCLUSION: Our work identified the genes encoding PMM isozymes in bread wheat and relatives, uncovered a unique PMM duplication event in diverse Triticeae species, and revealed the main active PMM isozymes in bread wheat tissues. The knowledge obtained here improves the understanding of PMM evolution in eukaryotic organisms, and may facilitate further investigations of PMM function in the temperature adaptability of bread wheat

Case report and literature review: Robot-assisted laparoscopic left renal mucinous cystadenocarcinoma radical nephrectomy

BackgroundMucinous cystadenocarcinoma (MC) of the kidney is a rare renal epithelial tumor originating from the renal pelvic urothelium. There are only a few published reports on MC. Due to its rare and unknown tissue origin, its diagnosis is difficult which almost can be diagnosed through the pathological method.Case presentationIn this case report, we report a female patient whose chief complaint was low back pain lasting for one month. The three-dimensional computed tomography scan of the urinary system detected approximately 7 cm of a left renal cystic mass. The renal cystic mass was diagnosed as MC after robot-assisted laparoscopic radical nephrectomy. The MC originated from the kidney after completing colorectal adenocarcinoma and ovarian adenocarcinoma.ConclusionsWe reported a case of MC of the kidney which was a rare renal tumor. We not only aimed to present an unusual case of MC and review the previous literature on its pathology and differential diagnosis, but also used new method to treat this type of tumor