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A photo-induced electron donor–acceptor (EDA) complex enabled tandem reaction of alkyne ketones via a radical difluoroalkylation/cyclization cascade sequence is reported. The EDA complex plays a key role, and the C – Br bond homolysis process may also be involved for this transformation. Varieties of difluoroalkyl-substituted thiofavones can be smoothly assembled in moderate to good yields under photocatalyst-, metal- and oxidant-free conditions, thus offering potential applications for pharmaceutical research. [ABSTRACT FROM AUTHOR]

Water jet propulsion pumps start at special stages such as mooring and sailing, the ship is in shallow water, and the underwater keen clearance (UKC) is relatively small, which is easy to induce underwater suction vortex near the inlet position and cause violent vibration of the pumping unit. The powerful suction effect of the water-jet propulsion pump can draw in debris from the bottom of the riverbed, causing damage to the propulsion pump. This research investigated the suction effect of water jet propulsion pump under different UKC conditions. A flow field analysis method based on the entropy weight theory was constructed to reveal the flow characteristics of the flow field where the underwater suction vortex occurs. The research found that the suction effect on the flow field tends to stabilize under the condition of UKC greater than 2.5D0. After UKC reaches 4.2D0, suction effects essentially cease to create large-scale shear stresses near the riverbed. In addition, this research analyzes the vorticity field using vorticity and net circulation to elucidate the vortex strength within the flow field under different UKC conditions. The probability of generation of underwater suction vortices will be greatly reduced when the UKC is greater than 0.83D0. [ABSTRACT FROM AUTHOR]

Objective To investigate the epidemiologic profile of contamination by multiple respiratory viruses (including influenza virus, rhinovirus, adenovirus, and respiratory syncytial virus) in the environments of medical institutions in Changsha City in 2023, aiming to provide scientific evidence for the formulation of infection control measures. Methods A total of 663 environmental samples were collected from 11 medical institutions in Changsha City, encompassing various types such as air, desktops, countertops, trash cans, power switches, door handles, elevator buttons, faucets in washrooms, water dispensers, and other surface swab samples. RT-PCR technology was employed to conduct nucleic acid testing for multiple respiratory viruses. The overall positive rates of respiratory viruses among different types of medical institutions, surveillance areas, and environmental samples were comparatively analyzed. Results The study revealed that the overall positive rate of nucleic acids for multiple respiratory viruses in the medical institution environments of Changsha City in 2023 was 10.41%, and the positive rates for influenza virus, rhinovirus, adenovirus, and respiratory syncytial virus were 0.90%, 5.28%, 3.77%, and 0.45%, respectively. Among the different types of medical institutions, general hospitals exhibited the highest positive rate of multiple respiratory viruses, reaching 15.22%, while specialized hospitals and other medical institutions (including welfare hospitals and physical examination institutions) had positive rates of 10.71% and 2.61%, respectively. In terms of surveillance areas, outpatient diagnosis and treatment areas demonstrated the highest overall positive rate of multiple respiratory viruses, standing at 12.50%, while public areas and inpatient wards exhibited lower positive rates. Additionally, swab samples collected from desktops, countertops, and trash cans showed the highest overall positive rate of multiple respiratory viruses, accounting for 15.45%. Samples from other sources, including faucets and water dispensers in washrooms, power switches, elevator buttons, door handles, and air samples, also exhibited varying degrees of positive rates. Statistical analysis demonstrated significant differences in the overall positive rates of multiple respiratory viruses among different types of medical institutions, surveillance areas, and environmental samples (P < 0.05).Conclusion The presence of multiple respiratory viruses in the environments of medical institutions in Changsha City in 2023 suggests the urgent need for enhanced epidemiologic surveillance and disinfection measures to effectively prevent and control nosocomial infections. [ABSTRACT FROM AUTHOR]

As a special type of through-flow device, bulb turbine pumps have been widely used in the Eastern Route of the South-to-North Water Diversion Project due to their compact structure, flexible installation process, easy maintenance, high efficiency, and strong adaptability. Therefore, structural improvements to enhance their safety and stability through fluid–structure interaction analysis have significant engineering value. This paper conducts static and transient fluid–structure interaction analyses of the bulb turbine pump structure. The results show that the rotor structure experiences the greatest deformation under low-flow conditions, with maximum deformation (2.13 mm) occurring at the leading edge of the impeller inlet and decreasing radially along a gradient distribution. The damping effect of water changes the mode shapes of the rotor structure, and although the vibration modes under wet conditions are similar to those in the air, the frequencies decrease to varying degrees. In transient analyses under different conditions, the total deformation of the rotor system is greater than in static analyses, showing significant regularity. Under low-flow conditions, the deformation of the pressure surface at the inlet and outlet of the blade tip is greater than that of the suction surface, with a maximum total deformation of 3.656 mm. The maximum total deformation under design flow is 3.337 mm; under high flow, it is 2.646 mm. The total deformation of the casing mainly occurs on both sides of the internal bulb body bottom support, with a maximum deformation of 2.0355 mm and an equivalent stress maximum of 44.848 MPa. The equivalent stress and total deformation distribution of the support structure are similar, located at the top support and trailing edge, with a maximum value of 22.94 MPa at the trailing edge. The research results provide technical references and theoretical foundations for the structural optimization of bulb turbine pumps. [ABSTRACT FROM AUTHOR]

Vortices always happen in the forebay and sump of a lateral pumping station, reducing its efficiency and wasting extra electric power. This study utilizes computational fluid dynamics (CFD) technology and a model test method to investigate the distribution of vortices in the forebay of a lateral pumping station of Y-shaped channel. Since the vortex is always accompanied by energy dissipation, the entropy production theory is also introduced to analyze the energy behaviors of the anti-vortex bottom sill. The research results indicate that the model test results verify the accuracy of the CFD. The bottom sill can effectively improve the flow pattern and reduce the rolling vortex behind the sill in the forebay, enhance the axial velocity uniformity at the inlet section of the sump, and reduce energy loss. The high entropy production zone is mainly distributed in the vortex core and the top of the sill. Therefore, the vortex and shock are the main causes of energy loss. The square bottom sill causes more severe energy loss compared to the trapezoidal bottom sill. The research results can provide references for setting up hydraulic optimization measures for similar lateral pumping stations. [ABSTRACT FROM AUTHOR]

Primula meishanensis K.Huang & Z.X.Fu, sp. nov., a new species of Primulaceae from Meishan City, Sichuan Province, China, is described and illustrated. The morphological data and phylogenetic analysis, based on the complete chloroplast genome, suggest that Primula meishanensis is a separate species closely related to Primula dejuniana. The complete chloroplast genome of Primula meishanensis was 152,175 bp and the complete chloroplast genome of Primula dejuniana was 151,988 bp. The new species differs from the latter by the solitary scape, the length of petiole, acute leaf blade apex and pin flower. The distribution map, morphological comparison of related species and conservation status of the new species are also provided. [ABSTRACT FROM AUTHOR]