To assess the role of in-flight transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), we investigated a cluster of cases among passengers on a 10-hour commercial flight. ...Affected persons were passengers, crew, and their close contacts. We traced 217 passengers and crew to their final destinations and interviewed, tested, and quarantined them. Among the 16 persons in whom SARS-CoV-2 infection was detected, 12 (75%) were passengers seated in business class along with the only symptomatic person (attack rate 62%). Seating proximity was strongly associated with increased infection risk (risk ratio 7.3, 95% CI 1.2-46.2). We found no strong evidence supporting alternative transmission scenarios. In-flight transmission that probably originated from 1 symptomatic passenger caused a large cluster of cases during a long flight. Guidelines for preventing SARS-CoV-2 infection among air passengers should consider individual passengers' risk for infection, the number of passengers traveling, and flight duration.
Objectives
In March 2020, a COVID‐19 outbreak in a major referral hospital in Hanoi, Vietnam led to 7664 patients and staff being sent into lockdown for 2 weeks, and more than 52,200 persons across ...49 provinces being quarantined. We assessed SARS‐CoV‐2 transmission patterns during this to‐date largest hospital outbreak in Vietnam using social network analysis (SNA).
Methods
We constructed a directed relational network and calculated network metrics for ‘degree’, ‘betweenness’, ‘closeness’ and ‘eigenvector’ centrality to understand individual‐level transmission patterns. We analysed network components and modularity to identify sub‐network structures with disproportionately big effects.
Results
We detected 68 connections between 46 confirmed cases, of whom 27 (58.7%) were ancillary support staff, 7 (15.2%) caregivers, 6 (13%) patients and 2 (4.4%) nurses. Among the 10 most important cases selected by each SNA network metric, transmission dynamics clustered in 17 cases, of whom 12 (70.6%) cases were ancillary support staff. Ancillary support staff also constituted 71.1% of cases in the dominant sub‐network and 68.8% of cases in the three largest sub‐communities.
Conclusions
We identified non‐clinical ancillary support staff, who are responsible for room service and food distribution in hospital wards in Vietnam, as a group with disproportionally big impacts on transmission dynamics during this outbreak. Our findings call for a holistic approach to nosocomial outbreak prevention and response that includes both clinical and non‐clinical hospital staff. Our work also shows the potential of SNA as a complementary outbreak investigation method to better understand infection patterns in hospitals and similar settings.
•Scrub typhus, caused by O. tsutsugamushi, is a common fever in Southeast Asia.•Delayed diagnosis of scrub typhus leads to high mortality rates, of up to 70%.•Primers and probe are designed to be ...specific to Southeast Asia's O. tsutsugamushi.•Developed RPA assay showed high sensitivity and high specificity.•Developed RPA assay is promising for field testing.
Scrub typhus, caused by Orientia tsutsugamushi, is a common fever in parts of Southern and Southeast Asia. As delayed diagnosis of scrub typhus leads to inappropriate treatment and high mortality rates, of up to 70%, sensitive and rapid detection of O. tsutsugamushi is required for timely and appropriate treatment. Molecular assays, such as PCR and real-time PCR, have been shown to be more sensitive than conventional immunoassay, however, they are only available in centralized laboratories. In contrast to PCR assays, Recombinase Polymerase Amplification (RPA) is conducted under a constant temperature ranging from 24°C to 45°C. Therefore, this technology is very promising for nucleic acid testing in the field, and in resource-limited areas. An RPA assay for the detection of O. tsutsugamushi based on the target gene encoding for the 47 kDa outer membrane protein has been reported, but the primer and probe sequences of this assay are suboptimal for detection of the majority of recently published sequences of O. tsutsugamushi isolates from Southeast Asia. We have established a real-time RPA assay with primer and probe sequences that are optimized for most Southeast Asia's isolates of O. tsutsugamushi. As a result, the new RPA assay showed better performance than the previous assay in detecting O. tsutsugamushi in clinical samples of scrub typhus cases found in Vietnam. The specificity of RPA assay was also evaluated using genomic DNA from microorganisms commonly encountered in the differential diagnosis of scrub typhus, and blood samples from healthy controls and O. tsutsugamushi negative confirmed cases.
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The development of Ni-based nanoalloys has been extensively explored due to their low cost, high activity, and durability in the hydrogen evolution reaction (HER). Structural design of Ni-based ...nanoalloys is a promising approach to attain excellent electrocatalytic activity as well as stability of these catalysts. This study reports a facile method to prepare NixRhy nanosponges while using NaBH4 as a reducing agent without any surfactant. The ratio of Ni and Rh has been changed to obtain various NixRhy electrocatalysts (Ni, Ni3Rh1, Ni1Rh1, Ni1Rh3, and Rh), respectively. Among the prepared catalysts, Ni1Rh3 electrocatalyst exhibits a high electrocatalytic activity with an overpotential of 48 mV at a current density of −10 mA cm−2 and a superior stability even after 2000 cycles of CV in 0.5 M H2SO4 electrolyte. In addition, the Ni1Rh3 electrocatalyst shows good electrocatalytic activity in 1.0 M KOH electrolyte compared to commercial Pt/C (20 wt% of Pt) (c-Pt/C). Moreover, the overall water splitting system of the Ni1Rh3 cathode and the commercial RuO2 anode is evaluated, not only exhibiting excellent performance with a potential of 1.52 V at a current density of 10 mA cm−2, but also proving very stable operation for over 100,000 s in 1.0 M KOH electrolyte.
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•NiRh alloy nanosponges are prepared using a facile method without any surfactant.•Rh-rich NiRh alloy nanosponges retain high crystallinity.•Electronic coupling between Ni and Rh atoms can enhance the HER activity.•NiRh nanosponges exhibit excellent HER performance.
Development of highly efficient electrocatalysts to produce hydrogen has been a significant topic over the past few decades. Currently, the platinum metal group shows the best catalytic performance ...for the hydrogen evolution reaction (HER), but the high cost and low abundance of these materials limit their wider application. Therefore, we synthesized transition-metal-based NiCoS along with carbon dots (C-dots) as a structure-directing agent by a hydrothermal method. We also synthesized sulfur-doped NiCo, where the sulfur enhances the conductivity of the catalysts. Herein, the synthesis temperatures were changed in the range from 120 to 240 °C. Among all, NiCoS synthesized at 150 °C shows the best HER performance capabilities. In more detail, NiCoS prepared at this temperature exhibits an onset potential of 96 mV and an overpotential of 232 mV. Especially, as-prepared NiCoS nanoflower subjects to long-term stability over 20 h at a current density of 10 mA/cm2, making it a promising low-cost candidate for hydrogen production.
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•A carbon-dot (C-dot) assisted 3D nanoflower-like NiCoS electro-catalyst is synthesized.•The homogeneous growth of nano-sheets with void structure provides a large surface area.•Sulphur-doped NiCo synthesized at 150 °C exhibits the highest electro-catalytic activity.•The C-dot acts as a protective layer for NiCo and creates easy routes for electron transfers.
In this study, we report a facile synthetic pathway to three-dimensional (3D) Pd nanosponge-shaped networks wrapped by graphene dots (Pd@G-NSs), which show superior electrocatalytic activity toward ...the hydrogen evolution reaction (HER) and exhibited excellent long-term stability in acidic media. Pd@G-NSs were synthesized by simply mixing Pd precursors, reducing agent, carbon dots (Cdots), and Br– ion at 30 °C. Experimental results and density functional theory (DFT) calculations suggested that the Br– ions played an essential role in accelerating the exfoliation of Cdot, supplying graphene layers, which could wrap the nanosponge-shaped Pd and finally form Pd@G-NS. In the absence of the Br– ions, only aggregated Pd nanoparticles (NPs) were formed and randomly mixed with Cdots. The resultant Pd@G-NS exhibited a high electrochemically active surface area and accelerated charge transport characteristics, leading to its superior electrocatalytic activity toward the HER in acidic media. The HER overpotential of Pd@G-NS was 32 mV at 10 mA cm–2, and the Tafel slope was 33 mV dec–1. Furthermore, the unique Pd@G-NS catalyst showed long-term stability for over 3000 cycles in acidic media as well, owing to the protection of Pd nanosponges by graphene dot wrapping. The overall HER performance of the Pd@G-NS catalyst exceeded that of commercial Pt/C.
The explosive development of electrical engineering in the early 19th century marked the birth of the 2nd industrial revolution, with the use of electrical energy in place of steam power, as well as ...changing the history of human development. The versatility of electricity allows people to apply it to a multitude of fields such as transportation, heat applications, lighting, telecommunications, and computers. Nowadays, with the breakout development of science and technology, electric energy sources are formed by many different technologies such as hydroelectricity, solar power, wind power, coal power, etc. These energy sources are connected to form grid systems to transmit electricity to cities, businesses and homes for life and work. Electrical energy today has become the backbone of all modern technologies. To ensure the safe, reliable and energy-efficient operation of the grid, a wide range of grid management applications have been proposed. However, a significant challenge for monitoring and controlling grids is service response time. In recent times, to solve this problem, smart grid management applications based on IoT and edge computing have been proposed. In this work, we perform a comprehensive survey of edge computing for IoT-enabled smart grid systems. In addition, recent smart grid frameworks based on IoT and edge computing are discussed, important requirements are presented, and the open issues and challenges are indicated. We believe that in the Internet of Things era, the smart grid will be the future of energy. We hope that these study results will contribute important guidelines for in-depth research in the field of smart grids and green energy in the future.
A new type of three-dimensional PtMo nanosponge wrapped with graphene dots (abbreviated as 3D PtxMo1-x@graphene) has been developed for catalyzing the hydrogen evolution reaction (HER). The ...graphene-dot wrapping takes place via the exfoliation of carbon dots during the co-reduction of Pt/Mo precursors and carbon dots at a low temperature in an aqueous solution. The synergistic effects of inner metallic alloy networks and outer graphene dots in the 3D PtxMo1-x@graphene are responsible for the outstanding HER performance and superb durability in both acidic and alkaline electrolytes. The 3D PtxMo1-x@graphene shows a low Tafel slope of 32 mV/dec and 51 mV/dec together with a low overpotential of 32 mV and 97 mV at a current density of −10 mA cm−2 in acidic and alkaline media, respectively. The catalyst also shows superb stability, as confirmed by a large amount of repeated potential cycling exceeding 5000 cycles in acidic solution and long-term durability of over 50,000 seconds in an alkaline solution. This work provides a new feasible mean of synthesizing graphene-dot-wrapped Pt-based nanostructures with highly efficient catalytic activity and superb stability for HER without the need for surfactants or stabilizers.
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A single-layered slot antenna system working at 5.8 GHz Industrial, Scientific and Medical (ISM) band is proposed for in-band full duplex (IBFD) operation applications without the use of a coupler. ...First, high isolation is achieved by strong separation of even- and odd-mode feeds. The microstrip-coupled coplanar waveguide (CPW) is used at Port 1 (TX port) to excite a stepped-slot antenna in the CPW odd mode. On the opposite side, a microstrip T-junction power divider is employed at Port 2 (RX port) to feed two offset-fed stepped-slot antennas in even mode. Second, isolation is further improved by 30 dB by using a lumped capacitor at the termination of the CPW. The measured isolation between the two ports is about 50 dB across the bandwidth. The measured −10 dB bandwidth of Port 1 is 0.49 GHz (8.5%), while that of Port 2 is 1.06 GHz (18.3%). The gains of TX and RX antennas are 5.4 and 5.8 dBi at 5.8 GHz. The proposed antenna can also be deployed as a dual-polarized antenna. Mathematical analysis and equivalent transmission line circuit models are provided to give physical insight into the working principals of the antenna with validation from ANSYS HFSS simulation.
For the first time, a versatile, novel and environmentally-friendly aerogel was successfully fabricated from rice straw – one of the most abundant agricultural waste in South-east Asia. The final ...product is able to be applied in a wide range of applications including oil-spill cleaning, thermal insulation and acoustic absorption. The fabrication process is simple, cost-efficient and totally green without disposal of harmful by-products into the environment. Specifically, rice straw fibers were dispersed along with reinforcers (PVA or cationic starch) followed by freeze-drying to form shaped aerogels. Those samples were then turned into hydrophobic by coating with MTMS using chemical vapor deposition (CVD) method to produce aerogels with exceptional water repellency (WCA exceeding 1500). The morphology, pore structure and physical properties of the aerogels were characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA), thermal conductivity, water contact angle (WCA) measurements, oil adsorption and sound absorption measurements. The aerogel samples exhibit extremely low densities (0.05–0.06 g/cm3), high porosities (~97%), excellent heat reduction properties with low thermal conductivities (0.034–0.036 W/m.K), good mechanical properties (Young modulus up to 47 kPa) and oil adsorption efficiency proven with the capacity up to 13 g/g. In addition, huge potential of rice straw aerogels in sound absorption applications is also demonstrated with high noise reduction coefficient (up to 0.6). The samples still retain their thermal insulation, sound insulation capability and hydrophobicity after 2-month exposure in ambient environment.
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•Rice straw is converted into aerogel by a simple and efficient fabrication process.•PVA and cationic starch are used as crosslinking agents.•Rice straw – PVA aerogel is the strongest sample.•Exceptional hydrophobicity is found for the aerogels with high water contact angles.•The aerogels have high potential in thermal insulation, sound absorption and oil spill cleaning.
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