Are coveralls required as personal protective equipment during the management of COVID-19 patients?

Objectives Few studies have investigated the contamination of personal protective equipment (PPE) during the management of patients with severe-to-critical coronavirus disease (COVID-19). This study aimed to determine the necessity of coveralls and foot covers for body protection during the management of COVID-19 patients. Methods PPE samples were collected from the coveralls of physicians exiting a room after the management of a patient with severe-to-critical COVID-19 within 14 days after the patient’s symptom onset. The surface of coveralls was categorized into coverall-only parts (frontal surface of the head, anterior neck, dorsal surface of the foot cover, and back and hip) and gown-covered parts (the anterior side of the forearm and the abdomen). Sampling of the high-contact surfaces in the patient’s environment was performed. We attempted to identify significant differences in contamination with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) between the coverall-only and gown-covered parts. Results A total of 105 swabs from PPEs and 28 swabs from patient rooms were collected. Of the PPE swabs, only three (2.8%) swabs from the gown-covered parts were contaminated with SARS-CoV-2. However, 23 of the 28 sites (82.1%) from patient rooms were contaminated. There was a significant difference in the contamination of PPE between the coverall-only and gown-covered parts (0.0 vs 10.0%, p = 0.022). Conclusions Coverall contamination rarely occurred while managing severe-to-critical COVID-19 patients housed in negative pressure rooms in the early stages of the illness. Long-sleeved gowns may be used in the management of COVID-19 patients.

Determination of Appropriate Personal Protective Equipment for Management of Patients With COVID-19

Objectives Few studies have investigated the contamination of personal protective equipment (PPE) during the management of patients with severe to critical coronavirus disease (COVID-19). This study aimed to determine the necessity of coveralls and foot cover for body protection during the management of patients with COVID-19. Methods PPE samples were collected from physicians exiting a room after the management of a patient with severe to critical COVID-19 who was within 14 days after symptom onset. The PPE sites were categorized into coverall-only parts (the frontal surface of the head, anterior neck, dorsal surface of the foot cover, and back and hip) and gown-covered parts (the anterior side of the forearm and the abdomen). Environmental sampling was performed in patient rooms. We tried to identify significant differences in contamination with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) between the coverall-only and gown-covered parts. Results A total of 105 swabs from PPE and 28 swabs from patient rooms were collected. Of the PPE swabs, only three (2.8 %) swabs from gown-covered parts were contaminated by SARS-CoV-2. However, 23 of the total 28 sites (82.1%) from patient rooms were contaminated. There was significant difference in the contamination of PPE between coverall-only and gown-covered parts (0.0 vs 6.7%, p = 0.022). Conclusions Coverall contamination rarely occurred while managing severe to critical COVID-19 patients residing in negative pressure rooms in the early stages of the illness. Long-sleeved gowns may be used safely in the management of COVID-19 patients.

MEASURING THE SOIL COMPACTION ZONE AND PRESSURE OF DEFORMED SOIL ON UNDERGROUND OBJECTS WITH AN ASYMMETRIC CYLINDRICAL TIP

At trenchless laying of engineering communications in soil the method of static puncture has received wide application at formation of a well. Power plants that implement it have small dimensions, which make them more effective in laying distribution engineering networks in tight urban conditions. Problem. The main disadvantages of the method are the low accuracy of the trajectory and the significant stress in the soil after its compaction, which can lead to the destruction of adjacent underground objects. The first disadvantage is solved by controlling the trajectory of the soil-piercing working body. To solve the second question, it is necessary to know and take into account the specifics of the formation of communication cavities in the soil with an asymmetric tip, which is used for this purpose. Goal. The aim of the work is to establish the regularity of the process of soil puncture by the soil-piercing working body with an asymmetric tip in the form of a cylinder cut at an angle. Methodology. The approaches adopted in the work to solve this goal are based on the theories of deep soil cutting, scientific foundations of soil mechanics, their normative physical and mechanical properties and the law of conservation of soil mass before and after compaction. Results. The calculated dependences for determining the size of the destructive zone from the elastic-plastic deformation of the soil during its puncture by an asymmetric tip with a frontal surface in the form of a beveled cylinder and the pressure of the deformed soil on underground objects are obtained. It is established that the maximum size of the destruction zone and its pressure on underground objects will occur in solid sand. With a tip diameter of 0.3 m, their values can reach 5 m and 0.245 MPa, respectively. Originality. The obtained regularities of soil puncture by a working body with an asymmetric tip in the form of a beveled cylinder made it possible to get an idea of the influence of its deformed state on adjacent communications depending on geometric parameters of the tip and physical and mechanical properties of soils. Practical value. The obtained results can be recommended in the design and determination of technological capabilities of installations for static soil puncture.

First record of the freshwater copepod Mesocyclops paranaensis Dussart & Frutos, 1986 (Copepoda: Cyclopoida: Cyclopidae) from Colombia

The Neotropical free-living freshwater cyclopoid copepod Mesocyclops paranaensis Dussart & Frutos, 1986 was found in a small temporal pond in La Guajira, northern Colombia. Hitherto, it has been reported from Argentina, Paraguay, and Brazil. This is the first record of this species in Colombia, its northernmost finding in South America, and the fourth locality in which this species has been recorded from. Mesocyclops paranaensis can be distinguished from its closest congeners by a unique combination of the characters of the female, including: 1) leg 4 intercoxal sclerite with two large, acute projections; 2) P3, P4 intercoxal sclerite caudal surface lightly pilose; 3) seminal receptacle with narrow lateral arms and weakly convex anterior margin; 4) second antennary endopodite with seven setae, and insertion of antennary exopodal seta with adjacent spinules; 5)frontal surface of P1 basipodite ornamented with long spinules; 6) posterior margin of anal somite with continuous row of spinules; and 7) inner margin of caudal ramus hirsute. The Colombian population shows some subtle morphological differences with respect to previous reports.

Convection initiation and bore formation following the collision of mesoscale boundaries over a developing stable boundary layer: a case study from PECAN

This observational study documents the consequences of a collision between two converging shallow atmospheric boundaries over the central Great Plains on the evening of 7 June 2015. This study uses data from a profiling airborne Raman lidar (the Compact Raman Lidar, or CRL) and other airborne and ground-based data collected during the Plains Elevated Convection At Night (PECAN) field campaign to investigate the collision between a weak cold front and the outflow from a MCS. The collision between these boundaries led to the lofting of high-CAPE, low-CIN air, resulting in deep convection, as well as an undular bore. Both boundaries behaved as density currents prior to collision. Because the MCS outflow boundary was denser and less deep than the cold-frontal airmass, the bore propagated over the latter. This bore was tracked by the CRL for about three hours as it traveled north over the shallow cold-frontal surface and evolved into a soliton. This case study is unique by using the high temporal and spatial resolution of airborne Raman lidar measurements to describe the thermodynamic structure of interacting boundaries and a resulting bore.

Studying the Effect of Light Incidence Angle on Photoelectric Parameters of Solar Cells by Simulation

It is crucial to examine the dependence of photoelectric parameters of solar cells on the light incidence angle. In the present study, two solar cell models have been developed using the Sentaurus Technology Computer-Aided Design software package. The light spectrum AM1.5 has been directed on the frontal surface of solar cells at different angles. It has been found that the angular coefficient of the photoelectric parameters of a solar cell with nanoparticles included, is two times more than that of a simple solar cell. Besides, it has been found that the efficiency of platinum nanoparticles induced solar cells is 2.15 times greater than simple solar cell efficiency. When the light incidence angle has been varied from 0 to 60 degrees, the short-circuit current has changed by 11% for simple solar cells and by 10% for solar cells with nanoparticles. Further, it has been observed that the variation of power for simple solar cells is 12.5%, while it is 10.5% for solar cells with nanoparticles. In addition, the short-circuit current of solar cells with nanoparticles has been found to be linear within a light incidence angle ranging from 0 to 60 degrees.

Study of the Spatial Distribution of Forces and Stresses on Wear Surfaces at Optimization of the Excavating Part of an Earthmoving Machine Transverse Profile

The relevance of this research lies in the need to develop a scientifically-grounded methodology for designing the optimal profile of the contact frontal surface of an energy-efficient earthmoving machine operating device, which ensures the redistribution of resistance forces along the cutting elements during the excavation of frozen soil when extracting hydrocarbons. The relevance is confirmed by the need to improve domestic methods for designing the profiles of effective operating devices, ensuring the excavation of frozen soils during the laying of oil and gas pipelines and geological exploration in permafrost areas. Increasing the energy efficiency and service life of highly loaded ripper teeth is done by optimizing the geometric profile and designing a spatial shape that provides minimal resistance to cutting the soil. The object of the research is the process of dynamic interaction of the ripper tooth cutting profile with the frozen soil environment. The research method used was kinematic analysis and force calculation. The cyclic process of dynamic loading of the ripper operating device was investigated. The methodology of system analysis, as well as the method of distribution of resistance forces over the geometric elements of the cutting edge, were used. The mathematical apparatus has been effectively applied to establish the dependences of the change in energy and power properties on performance indicators, soil rheology, and dynamic loads of the ripper tooth. The process of interaction of the ripper tooth tip with frozen soil was investigated. A method for substantiating the design parameters of the operating device by using Legendre polynomials was proposed. Separate calculation results subject to the introduced restrictions were presented for the condition for solving the problem. The optimal parameters of the transverse profile of the contact frontal surface of the earth-moving machine operating device were determined taking into account the coefficient of reducing the fracture resistance of frozen soils.

High-temperature effect of a gas jet of reactants on the front plate

The paper introduces the results of measuring and predicting the heat and force effect of jets of high-temperature reacting mixtures on the oxygen-methane, oxygen-alcohol components when acting on the front plate in the near field of the jet. A high-temperature supersonic gas jet flows out of a model chamber with a Laval nozzle into a medium with atmospheric pressure at a degree of off-design ratio of about unity. In the chamber, ignition and stable combustion of a mixture of selected substances occur, the ratio of these substances providing a stagnation temperature in the range of 1900 ... 3400 K. The pressure distribution function on the front plate obtained in the experiment is used. The proposed model of the high-temperature flow effect on the frontal surface can be used to test software systems and determine the levels of thermal effect during sample tests.

Измерение существенно нестационарных тепловых потоков градиентным датчиком на основе висмута

In this work we performed calibration of the gradient heat flux sensor made of bismuth single crystal. The value of the volt-watt sensitivity of the sensor is found and a data processing method based on the one-dimensional heat equation for a thin plate is presented. An experimental study of the heat flux on the frontal surface of the cylinder after a laser discharge was carried out. The data obtained as a result of the experiment were processed by the proposed method.