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Multiple DC microgrids are interconnected to form a DC microgrid cluster, which can effectively improve the renewable energy consumption capacity and power supply reliability of the microgrid cluster through sharing of energy storage among the participating DC microgrids. However, the existing methods are not able to flexibly coordinate the power flows between DC microgrids connected by a multiport converter. In this paper, a distributed cooperative control method is proposed for a DC microgrid cluster with multiple voltage levels connected by a multi-port interconnected converter. A multi-active-bridge (MAB) converter acts as a bridge for power exchange among microgrids, enabling the sharing of distributed energy storage among microgrids under a sparse communication network. The improved secondary control overcomes the drawbacks of droop control and achieves deviation-free voltage regulation and accurate load/source sharing of the energy storage converters within the cluster. The proposed secondary control can be used to retrofit the existing DC distribution grids to permit access of renewable energy. In addition, the improved voltage observer provides the voltage information of other nodes in a microgrid in addition to the energy storage information, reducing the voltage estimation error caused by the uneven distribution of energy storages. Finally, hardware-in-the-loop (HiL) experiments of the cluster with three DC microgrids verify the control performance, the flexible plug-and-play capability, and the high tolerance of communication failure.

AbstractGenus Penicillium comprising the most important and extensively studied fungi has been well-known as a rich source of secondary metabolites. Our study aimed to analyze and investigate biological activities, including in vitro anti-cancer, anti-inflammatory and anti-diabetic properties, of metabolites from a marine-derived fungus belonging to P. levitum. The chemical compounds in the culture broth of P. levitum strain N33.2 were extracted with ethyl acetate. Followingly, chemical analysis of the extract leaded to the isolation of three ergostane-type steroid components, namely cerevisterol (1), ergosterol peroxide (2), and (3β,5α,22E)-ergosta-6,8(14),22-triene-3,5-diol (3). Among these, (3) was the most potent cytotoxic against human cancer cell lines Hep-G2, A549 and MCF-7 with IC50 values of 2.89, 18.51, and 16.47 µg/mL, respectively, while the compound (1) showed no significant effect against tested cancer cells. Anti-inflammatory properties of purified compounds were evaluated based on NO-production in LPS-induced murine RAW264.7 macrophages. As a result, tested compounds performed diverse inhibitory effects on NO production by the macrophages, with the most significant inhibition rate of 81.37 ± 1.35% at 25 µg/mL by the compound (2). Interestingly, compounds (2) and (3) exhibited inhibitory activities against pancreatic lipase and α-glucosidase enzymes in vitro assays. Our study brought out new data concerning the chemical properties and biological activities of isolated steroids from a P. levitum fungus.

This paper presents the design of three-port converters (TPCs) for smooth transitions (i.e., fast settling time, and no obvious overshoot/undershoot) of 7 distinctive operating modes, depending on sources and loads scheduling. Two viable converter configurations have been identified and selected for further analysis and design of PV-battery systems. Conventionally, mode transition is achieved by assigning specific switching patterns through feedback signals and appropriate control algorithms. This incurs a delay in the response and unavoidable noise in the circuit. Additionally, in TPCs, three voltage sensors and three current sensors are generally required for decision making in mode selection, where errors in sensors may lead to an inaccurate response. This paper presents a new control strategy where the number of switching patterns is significantly reduced to 3 patterns instead of minimum 5 patterns for existing reported topologies. Therefore, decisions are simplified so that the transition occurs naturally based on the power availability and load demand but not deliberately as in the conventional method. In addition, instead of six sensors, three voltage sensors and only one current sensor are required to achieve all the necessary operations, namely, MPPT, battery protection, and output regulation. Moreover, these sensors do not participate in mode selection decision, which leads to seamless and fast mode transition. In addition, this work considers two bidirectional ports as compared with only one bidirectional port in most reported topologies. This configuration enables both standalone and DC grid-connected applications. Experimental results are reported to verify the proposed solution.

Lei Chen,1 Kun Chi,2 Huaguo Xiang,3 Yan Yang4 1Department of Emergency Medicine, Xiang’an Hospital of Xiamen University, Xiamen, 361101, People’s Republic of China; 2Department of Nursing, Qingdao Municipal Hospital (Group), Qingdao 266071, People’s Republic of China; 3Medical Laboratory, Shenzhen Baoan District Fuyong People’s Hospital, Shenzhen 518103, People’s Republic of China; 4Department of Gastroenterology, Central People’s Hospital of Tengzhou, Tengzhou 277500, People’s Republic of ChinaCorrespondence: Yan YangDepartment of Gastroenterology, Central People’s Hospital of Tengzhou, Tengzhou, Shandong 277500, People’s Republic of ChinaEmail yangyandoctor0623@163.comBackground: Circular RNAs (circRNAs) play an essential role in the pathogenesis of malignant tumors, including gastric cancer (GC). However, the effect of circ_0032821 on GC remains largely unknown.Methods: QRT-PCR assay was employed to examine the levels of circ_0032821, CEP128 mRNA and miR-1236-3p. RNase R digestion assay was utilized to verify the feature of circ_0032821. Cell Counting Kit-8 (CCK-8) assay and transwell assay were adopted to evaluate cell proliferation and metastasis. The level of glycolysis was evaluated through detecting ECAR, OCR, lactate production, glucose uptake and ATP synthesis. Dual-luciferase reporter assay and RIP assay were conducted to analyze the relationship between miR-1236-3p and circ_0032821 or HMGB1. Western blot assay was adopted for high mobility group box 1 (HMGB1) level. Murine xenograft model assay was utilized for the effect of circ_0032821 in vivo.Results: High level of circ_0032821 was observed in GC tissues and cells. Silencing of circ_0032821 markedly repressed cell proliferation, metastasis and glycolysis in GC cells in vitro and blocked tumorigenesis of GC in vivo. For mechanism analysis, circ_0032821 was identified as the sponge of miR-1236-3p and HMGB1 was the target gene of miR-1236-3p. Moreover, miR-1236-3p suppression restored the influences of circ_0032821 deficiency on GC cell proliferation, metastasis and glycolysis. Overexpression of miR-1236-3p relieved the malignant behaviors of GC cells by targeting HMGB1.Conclusion: Circ_0032821 accelerated GC development through elevating HMGB1 expression via sponging miR-1236-3p.Keywords: gastric cancer, circ_0032821, miR-1236-3p, HMGB1

Kui Chi,1 Jinwen Zhang,1 Huanhuan Sun,1 Yang Liu,1 Ye Li,2 Tao Yuan,1 Feng Zhang1 1Department of Vascular Surgery, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei 050000, People’s Republic of China; 2Department of Anesthesiology, The Second Hospital of Hebei Medical University, Shijiazhuang, Hebei 050000, People’s Republic of ChinaCorrespondence: Feng Zhang Email zhangfeng_12@126.comBackground: Atherosclerosis can lead to multiple cardiovascular diseases, especially myocardial infarction. Long noncoding RNAs (lncRNAs) are involved in multiple diseases, including atherosclerosis. LncRNA HOXA-AS3 was found to be notably upregulated in atherosclerosis. However, the biological function of HOXA-AS3 during the occurrence and development of atherosclerosis remains unclear.Materials and Methods: Human vascular endothelial cells (HUVECs) were treated with oxidized low-density lipoprotein (oxLDL) to mimic atherosclerosis in vitro. Gene and protein expressions in HUVECs were detected by RT-qPCR and Western blot, respectively. Cell proliferation was tested by CCK-8 and Ki67 staining. Cell apoptosis and cycle were measured by flow cytometry. Additionally, the correlation between HOXA-AS3 and miR-455-5p was confirmed by dual luciferase report assay and RNA pull-down. Finally, in vivo model of atherosclerosis was established to confirm the function of HOXA-AS3 during the development of atherosclerosis in vivo.Results: LncRNA HOXA-AS3 was upregulated in oxLDL-treated HUVECs. In addition, oxLDL-induced growth inhibition of HUVECs was significantly reversed by knockdown of HOXA-AS3. Consistently, oxLDL notably induced G1 arrest in HUVECs, while this phenomenon was greatly reversed by HOXA-AS3 siRNA. Furthermore, downregulation of HOXA-AS3 notably inhibited the progression of atherosclerosis through mediation of miR-455-5p/p27 Kip1 axis. Besides, silencing of HOXA-AS3 notably relieved the symptom of atherosclerosis in vivo.Conclusion: Downregulation of HOXA-AS3 significantly suppressed the progression of atherosclerosis via regulating miR-455-5p/p27 Kip1 axis. Thus, HOXA-AS3 might serve as a potential target for the treatment of atherosclerosis.Keywords: atherosclerosis, lncRNA HOXA-AS3, miR-455-5p, p27 Kip1

Over the past decade, the cyber security of power systems has been widely studied. Most previous studies have focused on cyber physical attacks, and barely considered one typical cyber attack: availability attack. We propose a hybrid attack model and apply conventional state estimation processes to study cyber attacks on power grids in this paper. The proposed model considers both integrity attack and availability attack simultaneously. Compared with the particular attack, namely, false data injected attack, we analyze their consequences to power systems in the events of false negatives attack and false alarm attack. The results show that the hybrid attack can confuse the control center by manipulating the integrity and availability of measurements. More importantly, we evaluate the hybrid attack with different values of the cost ratio between integrity and availability attacks, and then verify that the hybrid attack can achieve the same goal with a reduced cost.

The penetration of power electronics into power generation and distribution systems has deepened in recent years, as prompted by the increasing use of renewable sources, the quest for higher performance in the control of power conversion, as well as the increasing influence of economic plans that necessitate power trading among different regions or clusters of power distribution. As a result of the increased use of power electronics for controlling power flows in power systems, interactions of power electronics systems and conventional synchronous machines' dynamics would inevitably cause stability and robustness concerns, which can be readily understood by the coupling effects among interacting dynamical systems of varying stability margins (or transient performances). In this article, we present the various problems of power electronics penetration into power grids and the implications on the stability and robustness of power networks. We specifically attempt to bring together two distinct perspectives, namely, bottom-up (local) and top-down (global) perspectives, and examine the current progress and future direction of research in power systems amidst the extensive deployment of power electronics.

Abstract Background Foot and ankle pain is common in the Australian adult population. People with musculoskeletal foot and ankle conditions are often referred for surgical opinion, yet how patients are managed prior to referral is largely unknown. The aim of this study was to determine the characteristics and management of patients with musculoskeletal foot and ankle complaints prior to public-sector orthopaedic referral in South Australia. Methods People with non-urgent foot or ankle complaints were recruited over a 12-month period from the waiting-lists of three tertiary hospitals in Adelaide, Australia. Participants completed a questionnaire on their medical history, duration and location of their foot or ankle complaint, diagnosis of their condition, previous treatment and medical imaging. The Manchester-Oxford Foot and Ankle Questionnaire, and the EuroQol-5D-5 L measured foot/ankle pain severity and health-related-quality-of-life (HRQoL). Descriptive statistics were generated for sample demographics, medical history and foot/ankle symptoms. Multivariable regressions were used to explore factors associated with foot/ankle pain severity and whether participants considered an operation necessary. Results Two hundred and thirty-three adults returned questionnaires, with a survey response rate of 38.4% (66.1% female, median age 57.7 years IQR 18.5, BMI 29.3 kg/m2 IQR 8.7). Half of the participants had seen a podiatrist (52.8%), and 36.5% did not see any other health professional prior to orthopaedic referral. Sixty-five (27.9%) had not yet been given a diagnosis. BMI was positively associated with foot/ankle pain severity (β 0.48, 95% CI 0.05, 0.92), while HRQoL had a negative association (β − 0.31, 95% CI -0.45, − 0.18). Participants told by their GP that they may need an operation were significantly more likely to consider surgery necessary (OR 31.41, 95% CI 11.30, 87.35), while older people were less likely (OR 0.94, 95% CI 0.90, 0.98). Conclusions More than one-third of the participants had not accessed allied-health care prior to specialist orthopaedic referral. Participants may consider their GPs opinion on the necessity of surgery compelling, and most expected to undergo surgery, but many couldn’t report their diagnosis. The discordance between the expectation of surgery and historically low surgical conversion rates suggests more work is necessary to improve the management of this group.

This study integrates the daily intercity migration data with the classic Susceptible-Exposed-Infected-Removed (SEIR) model to construct a new model suitable for describing the dynamics of epidemic spreading of Coronavirus Disease 2019 (COVID-19) in China. Daily intercity migration data for 367 cities in China were collected from Baidu Migration, a mobile-app based human migration tracking data system. Early outbreak data of infected, recovered and death cases from official source (from January 24 to February 16, 2020) were used for model fitting. The set of model parameters obtained from best data fitting using a constrained nonlinear optimisation procedure was used for estimation of the dynamics of epidemic spreading in the following months. The work was completed on February 19, 2020. Our results showed that the number of infections in most cities in China would peak between mid February to early March 2020, with about 0.8%, less than 0.1% and less than 0.01% of the population eventually infected in Wuhan, Hubei Province and the rest of China, respectively. Moreover, for most cities outside and within Hubei Province (except Wuhan), the total number of infected individuals is expected to be less than 300 and 4000, respectively.

This work applies a data-driven coding method for prediction of the COVID-19 spreading profile in any given population that shows an initial phase of epidemic progression. Based on the historical data collected for COVID-19 spreading in 367 cities in China and the set of parameters of the augmented Susceptible-Exposed-Infected-Removed (SEIR) model obtained for each city, a set of profile codes representing a variety of transmission mechanisms and contact topologies is formed. By comparing the data of an early outbreak of a given population with the complete set of historical profiles, the best fit profiles are selected and the corresponding sets of profile codes are used for prediction of the future progression of the epidemic in that population. Application of the method to the data collected for South Korea, Italy and Iran shows that peaks of infection cases are expected to occur before mid April, the end of March and the end of May 2020, and that the percentage of population infected in each city or region will be less than 0.01%, 0.5% and 0.5%, for South Korea, Italy and Iran, respectively.

Obstructive sleep apnea (OSA) remains a prominent disease state characterized by the recurrent collapse of the upper airway while sleeping. To date, current treatment may include continuous positive airway pressure (CPAP), lifestyle changes, behavioral modification, mandibular advancement devices, and surgical treatment. However, due to the desire for a more convenient mode of management, pharmacological treatment has been thoroughly investigated as a means for a potential alternative in OSA treatment. OSA can be distinguished into various endotypic or phenotypic classes, allowing pharmacological treatment to better target the root cause or symptoms of OSA. Some medications available for use include antidepressants, CNS stimulants, nasal decongestants, carbonic anhydrase inhibitors, and potassium channel blockers. This review will cover the findings of currently available and future study medications that could potentially play a role in OSA therapy.

This paper presents novel kernel adaptive filters with feedback, namely, kernel recursive maximum correntropy with multiple feedback (KRMC-MF) and its simplified version, a linear recurrent kernel online learning algorithm based on maximum correntropy criterion (LRKOL-MCC). In LRKOL-MCC and KRMC-MF, single output and multiple outputs based on single delay are utilized to construct their feedback structure, respectively. Compared with the minimum mean square error criterion, the maximum correntropy criterion (MCC) adopted by LRKOL-MCC and KRMC-MF captures higher order statistics of errors. The proposed filters are, therefore, robust against outliers. Therefore, the past information can be reused to improve filtering performance in terms of the steady-state mean square error. The convergence characteristics of the filter parameters in LRKOL-MCC and KRMC-MF are also derived. Simulations on chaotic time-series prediction and nonlinear regression illustrate the desirable accuracy and robustness of the proposed filters.

This paper presents a systematic topological study to derive all possible basic and non-isolated three-port converters (TPCs) using power flow diagrams. Unlike most reported TPCs with one bidirectional port, this paper considers up to two bidirectional ports and provides a comprehensive analytical tool. This tool acts as a framework for all power flow combinations, selection, and design. Some viable converter configurations have been identified and selected for further analysis.

Nobel metal composite aerogel fibers made from flexible and porous biopolymers offer a wide range of applications, such as in catalysis and sensing, by functionalizing the nanostructure. However, producing these composite aerogels in a defined shape is challenging for many protein-based biopolymers, especially ones that are not fibrous proteins. Here, we present the synthesis of silk fibroin composite aerogel fibers up to 2 cm in length and a diameter of ~300 μm decorated with noble metal nanoparticles. Lyophilized silk fibroin dissolved in hexafluoro-2-propanol (HFIP) was cast in silicon tubes and physically crosslinked with ethanol to produce porous silk gels. Composite silk aerogel fibers with noble metals were created by equilibrating the gels in noble metal salt solutions reduced with sodium borohydride, followed by supercritical drying. These porous aerogel fibers provide a platform for incorporating noble metals into silk fibroin materials, while also providing a new method to produce porous silk fibers. Noble metal silk aerogel fibers can be used for biological sensing and energy storage applications.

The power grid in a typical micro distribution system is non-ideal, presenting itself as a voltage source with significant impedance. Thus, grid-connected converters interact with each other via the non-ideal grid. In this study, we consider the practical scenario of voltage-source converters connected to a three-phase voltage source with significant impedance. We show that stability can be compromised in the interacting converters. Specifically, the stable operating regions in selected parameter space may be reduced when grid-connected converters interact under certain conditions. In this paper, we develop bifurcation boundaries in the parameter space with respect to Hopf-type instability. A small-signal model in the dq-frame is adopted to analyze the system using an impedance-based approach. Moreover, results are presented in design-oriented forms so as to facilitate the identification of variation trends of the parameter ranges that guarantee stable operation.

Despite the significant improvement on network performance provided by global routing strategies, their applications are still limited to small-scale networks, due to the need for acquiring global information of the network which grows and changes rapidly with time. Local routing strategies, however, need much less local information, though their transmission efficiency and network capacity are much lower than that of global routing strategies. In view of this, three algorithms are proposed and a thorough investigation is conducted in this paper. These algorithms include a node duplication avoidance algorithm, a next-nearest-neighbor algorithm and a restrictive queue length algorithm. After applying them to typical local routing strategies, the critical generation rate of information packets Rc increases by over ten-fold and the average transmission time 〈T〉 decreases by 70-90 percent, both of which are key physical quantities to assess the efficiency of routing strategies on complex networks. More importantly, in comparison with global routing strategies, the improved local routing strategies can yield better network performance under certain circumstances. This is a revolutionary leap for communication networks, because local routing strategy enjoys great superiority over global routing strategy not only in terms of the reduction of computational expense, but also in terms of the flexibility of implementation, especially for large-scale networks.

[This corrects the article DOI: 10.1371/journal.pone.0156756.].

OBJECTIVE: We studied the long-term outcome of radical cystectomy for transitional cell carcinoma and evaluated prognostic factors for disease specific survival. MATERIALS AND METHODS: A retrospective review was carried out for all cystectomies performed for transitional cell carcinoma between 1989 and 2002. Disease specific survival was correlated to patient, pathological and operative factors as well as to adjuvant therapy. RESULTS: Of the 133 cystectomies included, 100 were male and 33 were female patients. The median age was 69 years (range 43 to 86). The median follow up was 20 months (range 0 to 158). With univariate analysis, pT stage, N stage, lymph node density, carcinoma in-situ, surgical margin and post-operative radiotherapy to distant metastasis were predictive of disease specific survival. On the other hand, with multivariate analysis, only pT stage, lymph node density and post-operative radiotherapy to distant metastasis were predictive of disease specific survival. Within the group of node positive disease, lymph node density also predicted disease specific survival with both univariate and multivariate analyses. Patients with lymph node density 20% or below showed better disease specific survival. CONCLUSIONS: pT stage and lymph node density were found to be the most important predictive factors for disease specific survival after cystectomy in the Asian population.

High-throughput screening (HTS) is a powerful approach to drug discovery, but many lead compounds are found to be unsuitable for use in vivo after initial screening. Screening in small animals like C. elegans can help avoid these problems, but this system has been limited to screens with low-throughput or no specific molecular target. We report the first in vivo 1536-well plate assay for a specific genetic pathway in C. elegans. Our assay measures induction of a gene regulated by SKN-1, a master regulator of detoxification genes. SKN-1 inhibitors will be used to study and potentially reverse multidrug resistance in parasitic nematodes. Screens of two small commercial libraries and the full Molecular Libraries Small Molecule Repository (MLSMR) of ∼364,000 compounds validate our platform for ultra HTS. Our platform overcomes current limitations of many whole-animal screens and can be widely adopted for other inducible genetic pathways in nematodes and humans.

Stationary complex networks have been extensively studied in the last ten years. However, many natural systems are known to be continuously evolving at the local ("microscopic") level. Understanding the response to targeted attacks of an evolving network may shed light on both how to design robust systems and finding effective attack strategies. In this paper we study empirically the response to targeted attacks of the scientific collaboration networks. First we show that scientific collaboration network is a complex system which evolves intensively at the local level--fewer than 20% of scientific collaborations last more than one year. Then, we investigate the impact of the sudden death of eminent scientists on the evolution of the collaboration networks of their former collaborators. We observe in particular that the sudden death, which is equivalent to the removal of the center of the egocentric network of the eminent scientist, does not affect the topological evolution of the residual network. Nonetheless, removal of the eminent hub node is exactly the strategy one would adopt for an effective targeted attack on a stationary network. Hence, we use this evolving collaboration network as an experimental model for attack on an evolving complex network. We find that such attacks are ineffectual, and infer that the scientific collaboration network is the trace of knowledge propagation on a larger underlying social network. The redundancy of the underlying structure in fact acts as a protection mechanism against such network attacks.

Significant efforts are devoted to optimizing the efficiency of triboelectric energy harvesting systems, particularly through the design of an advanced power management system (PMS) for Triboelectric Nanoenerators (TENGs). A critical aspect of PMS is the design and control of switches. However, existing switches face significant limitations. For spark switches, precise control cannot be achieved, and electronic switches can only operate at voltages below several hundred volts which is limited by the risk of electrical breakdown. To address these limitations, a hybrid electronic‐spark switch power management system (HESS) is proposed. HESS changes the connection of capacitors from parallel to series by deploying a maximum voltage tracking switch components at the peak voltage point, resulting in a much‐elevated voltage level to activate the spark switch. This approach achieves precise control of the spark switch for the first time and significantly reduces the operating voltage of electronic switches. Through simulation and experimental verification, HESS achieves the control at a voltage level of 1.8 kV for spark switch, with an electrical component breakdown voltage of only 450 V. The power density of the HESS is 29.8 mW Hz−1 m−2, which is a new record for electronic switches. [ABSTRACT FROM AUTHOR]

The emergence of the novel coronavirus disease-19 (COVID-19) required a rapid shift from in-person instruction to remote learning in our second-semester general chemistry course at the United States Military Academy (USMA), a predominantly undergraduate institution that takes pride in faculty accessibility to students. The decision to conduct remote instruction took effect when students were on spring break; consequently, most students had limited academic resources in hand. This represented a significant paradigm shift for both USMA faculty and students since the institution places an emphasis on in-person engagements with students, as reflected by our low student-to-faculty ratio. We adapted our usual in-person, student-driven instructional method to the remote environment within a 7 day period, which impacted 174 students and six faculty course-wide who were new to the technology, resources, and methodology associated with remote instruction and learning. This communication discusses lessons learned from the transition to asynchronous remote teaching, with a critical focus on the advantages and disadvantages of the adopted teaching methodologies, and includes a discussion of course design and the corresponding adaptions to this new pedagogical environment. We anticipate that these accounts can be leveraged by the broader chemical sciences community to better inform the planning and execution of instruction in future academic terms under remote, in-person, or hybrid (partially remote and partially in-person) environments.