Extra Volume Research Articles

Mitigating saliva aerosol contamination in a dental school clinic

BackgroundTransmission of COVID-19 via salivary aerosol particles generated when using handpieces or ultrasonic scalers is a major concern during the COVID-19 pandemic. The aim of this study was to assess the spread of dental aerosols on patients and dental providers during aerosol-generating dental procedures.MethodsThis pilot study was conducted with one volunteer. A dental unit used at the dental school for general dental care was the site of the experiment. Before the study, three measurement meters (DustTrak 8534, PTrak 8525 and AeroTrak 9306) were used to measure the ambient distribution of particles in the ambient air surrounding the dental chair. The volunteer wore a bouffant, goggles, and shoe covers and was seated in the dental chair in supine position, and covered with a surgical drape. The dentist and dental assistant donned bouffant, goggles, face shields, N95 masks, surgical gowns and shoe covers. The simulation was conducted by using a high-speed handpiece with a diamond bur operating in the oral cavity for 6 min without touching the teeth. A new set of measurement was obtained while using an ultrasonic scaler to clean all teeth of the volunteer. For both aerosol generating procedures, the aerosol particles were measured with the use of saliva ejector (SE) and high-speed suction (HSS) followed a separate set of measurement with the additional use of an extra oral high-volume suction (HVS) unit that was placed close to the mouth to capture the aerosol in addition to SE and HSS. The distribution of the air particles, including the size and concentration of aerosols, was measured around the patient, dentist, dental assistant, 3 feet above the patient, and the floor.ResultsFour locations were identified with elevated aerosol levels compared to the baseline, including the chest of the dentist, the chest of patient, the chest of assistant and 3 feet above the patient. The use of additional extra oral high volume suction reduced aerosol to or below the baseline level.ConclusionsThe increase of the level of aerosol with size less than 10 µm was minimal during dental procedures when using SE and HSS. Use of HVS further reduced aerosol levels below the ambient levels.

Topological shadows and complexity of islands in multiboundary wormholes

Recently, remarkable progress in recovering the Page curve of an evaporating black hole (BH) in Jackiw-Teitelboim gravity has been achieved through use of Quantum Extremal surfaces (QES). Multi-boundary Wormhole (MbW) models have been crucial in parallel model building in three dimensions. Motivated by this we here use the latter models to compute the subregion complexity of the Hawking quanta of the evaporating BH in AdS3 and obtain the Page curve associated with this information theoretic measure. We use three- and n-boundary wormhole constructions to elucidate our computations of volumes below the Hubeny-Rangamani-Takayanagi (HRT) surfaces at different times. Time is represented by the growing length of the throat horizons corresponding to smaller exits of the multi-boundary wormhole and the evaporating bigger exit shrinks with evolving time. We track the change in choice of HRT surfaces with time and plot the volume with time. The smooth transition of Page curve is realized by a discontinuous jump at Page time in volume subregion complexity plots and the usual Page transition is realized as a phase transition due to the inclusion of the island in this context. We discuss mathematical intricacies and physical insights regarding the inclusion of the extra volume at Page time. The analysis is backed by calculations and lessons from kinematic space and tensor networks.

A passive thermal management system of Li-ion batteries using PCM composites: Experimental and numerical investigations

This paper is dedicated to the design of an optimal thermal management system using a PCM-Metal Foam composite at the scale of a Li-ion batteries cells. To study the ability of a PCM and a PCM- Metal foam composite to absorb the heat generated by a Li-ion cell, a mathematical and numerical model was developed. The modeling is based on the data collected from characterizing experiments conducted with a new experimental test bench developed in the CERTES lab. In order to characterize the thermal behavior of Li-ion cell, the developed two-dimensional numerical model integrates the Brinkmann-Forchheimer-extended Darcy equation, the enthalpy-porosity method and two-temperature energy equations. The numerical study was made by coupling Matlab and COMSOL Multiphysics. The results showed that the addition of an aluminum foam allows a more efficient thermal management of the cell. The optimization study showed that an underestimation of the thickness (mass of PCM required) leads to extreme temperatures. It was also found that the addition of an extra volume of PCM does not have a great influence on the cell surface temperature.

Extending Openhole Gravel-Packing Intervals through Enhanced Shunted Screens

Summary For offshore wells requiring sand control, it is beneficial to extend the openhole length to access more reserves with a reduced well count. In challenging environments (e.g., low fracture pressure, highly unconsolidated sand), gravel packing with shunt tubes has been used successfully to virtually ensure a complete pack, thereby minimizing the risk of sand-control failure. Although shunt-tube gravel-pack technologies already exist, several issues must be addressed to gravel pack longer wells. First, the extra volume of gravel passing through shunt-tube manifolds raises erosion concerns. Second, the burst rating of the entire shunt system needs to be increased to allow continuous packing through shunts in a heel-to-toe fashion. Third, higher leakoff through the packed interval might increase gravel concentration, which increases friction and the risk of bridging inside the shunts. This study discusses the development and testing of a modified shunted screen that could extend openhole gravel-packing lengths to more than 7,000 ft with zonal isolation. The first step was to use computational fluid dynamics (CFD) simulations to investigate the erosion-prone areas in our existing conventional shunted-screen-technology (SST) manifold design. The CFD results were then used to modify the manifold and make it more resistant to erosion. Prototypes were manufactured and erosion tests were conducted to validate and qualify the new design for targeted proppant concentrations, flow rates, and treatment volumes. Any weak areas found in the shunt system were modified to enable higher burst pressure. The modified shunt system was then independently tested to quantify the burst limits. The concerns regarding high leakoff, friction, and bridging inside the tubes were first addressed by means of experimentation. The first nozzle distance was then modified according to these results. Verification of the modified system design was performed by means of gravel-pack testing on a full-scale model. It was observed that the proposed enhanced-SST (ESST) had no erosion failure after 450,000 lbm of proppant at a slurry rate of 5 bbl/min. The proposed ESST was successfully tested for 10,000-psi burst pressure after the erosion test. The initial motivation, design changes, and tests that led to the development of the modified system are presented herein.

Analysis of One-Dimensional Compression under a Wide Range of Stress with Densely Arrayed BPM

In this paper, the densely arrayed bonded particle model is proposed for simulation of granular materials with discrete element method (DEM) considering particle crushing. This model can solve the problem of pore calculation after the grains are crushed, and reduce the producing time of specimen. In this work, several one-dimensional compressing simulations are carried out to investigate the effect of particle crushing on mechanical properties of granular materials under a wide range of stress. The results show that the crushing process of granular materials can be divided into four different stages according to er-logσy curves. At the end of the second stage, there exists a yield point, after which the physical and mechanical properties of specimens will change significantly. Under extremely high stress, particle crushing will wipe some initial information of specimens, and specimens with different initial gradings and void ratios present some similar characteristics. Particle crushing has great influence on grading, lateral pressure coefficient and compressibility of granular materials, and introduce extra irreversible volume deformation, which is necessary to be considered in modelling of granular materials in wide stress range.

COVID ‐19 transmission in cold chain: A safe and green new‐generation cold chain is demanded

<scp>COVID</scp> ‐19 transmission in cold chain: A safe and green new‐generation cold chain is demanded

Co-Reduction of Common Mode Noise and Loop Current of Three-Level Active Neutral Point Clamped Inverters

The increased switching frequency and speed of silicon carbide (SiC) MOSFETs lead to higher power density of inverters, but meanwhile resulting in weak electromagnetic interference (EMI). The impedance balance technique is a good way to reduce the common mode (CM) noise by making the voltage across the line impedance stabilization network (LISN) as small as possible. However, a side effect of this technique is the generation of relatively large loop current that circulates in the inverter. It can cause additional losses and cost, which can be a factor that stops the increase of the switching frequency by SiC MOSFET. This article, for the first time, analyzes the relationship between the CM noise and loop current of the three-level active neutral point clamped (ANPC) inverter, and proposes a co-reduction method for both. First, the CM noise and loop current are clarified for the ANPC inverter, and the analytical models for both are established. The conflict between the CM noise and loop current is introduced with a specific case by the existing design method. Then a co-reduction method is proposed and elaborated, which can both suppress the CM noise and the loop current. The extra cost and volume by the proposed method are also analyzed and are negligible. The design guideline is further shown for clarity. Finally, the analysis and proposed method is validated by the experiment.

Investigation of the microporous organization of 1,2-disubstituted polyacetylenes using low-temperature argon sorption and small-angle X-ray scattering

The extra free volume of glassy, highly permeable 1,2-disubstituted polyacetylenes is associated with the microporous organization of these polymers. In this work, the microporosity of poly(1-trimethylsilyl-1-propyne) (PTMSP) and poly(4-methyl-2-pentyne) (PMP) is investigated by two independent methods—convenient low-temperature Ar sorption and less commonly used small-angle X-ray scattering (SAXS). The Ar sorption data were analyzed in connection with the specific surface area, pore volume, and micropore size distribution. It is shown that the higher specific surface area, total pore volume, and micropore volume of PTMSP than those of PMP are associated with higher gas permeability coefficients. It was found that the Brunauer–Emmett–Teller-specific surface values obtained for PTMSP and PMP from argon sorption isotherms correlate with the specific surface values obtained from the SAXS method. The correlation of the specific surface values obtained from fundamentally different methods makes it possible to evaluate the small-angle scattering method as adequate for assessing the microporosity of polymeric materials. The microporosity of poly(1-trimethylsilyl-1-propyne) (PTMSP) and poly(4-methyl-2-pentyne) (PMP) is investigated by two independent methods—convenient low-temperature Ar sorption and less commonly used small-angle X-ray scattering (SAXS). The Brunauer–Emmett–Teller-specific surface values obtained for PTMSP and PMP from Ar sorption isotherms correlate with the specific surface values obtained from the SAXS method. The correlation of the specific surface values obtained from fundamentally different methods makes it possible to evaluate the small-angle scattering method as adequate for assessing the microporosity of polymeric materials.

A Compact Waveguide Slot Filtering Antenna Based on Mushroom-Type Surface

A mushroom-type surface-based waveguide slot filtering antenna is proposed herein. First, using a mushroom-type surface replacing the conventional metal plane in the bottom of a rectangular waveguide, a novel filtering waveguide is achieved. This filtering waveguide functions as a bandstop filter when the surface performs as a perfect magnetic conductor. Then, a filtering waveguide slot antenna is obtained by cutting radiating slots on the top of the filtering waveguide. Compared with a traditional waveguide slot antenna, the proposed antenna has nearly the same radiation characteristic while realizes an additional filter selectivity with almost no extra volume occupancy. A prototype is demonstrated in Ku -band with operating in 12.25–12.75 GHz and rejecting over 14.0–14.5 GHz, which can be a candidate for receiving antenna of satellite communication. The measured results agree well with the designed ones, showing a suppression level stronger than 40 dB in the rejecting band.

COVID-19 pandemic: Solid waste and environmental impacts in Brazil

The World Health Organization has recently declared South America the new epicenter of the COVID-19 pandemic, as Brazil has become one of the most affected countries. Besides public health and economic impacts, social isolation has also caused indirect environmental effects. The aim of this study was to assess environmental impacts caused by shifts on solid waste production and management due to the COVID-19 pandemic in Brazil. We have analyzed data from 30 cities, representing a population of more than 53.8 million people (25.4% of the Brazilian population). Unexpectedly, solid waste production in the main cities in Brazil has decreased during the social isolation period, possibly because of reduced activity in commercial areas. The latest data on solid waste in Brazil have revealed that more than 35% of medical waste has not been treated properly. Furthermore, improper disposal of facemasks has been reported in several cities and may increase the risk for COVID-19 spread. The suspension of recycling programs has hindered natural resources from being saved, with emphasis on 24,076 MWh of electric power and 185,929 m3 of potable water – respectively enough to supply 152,475 households and 40,010 people, over a month. Furthermore, total sale price for recyclable materials during the suspension of recycling programs reaches more than 781 thousand dollars, being these materials disposed in landfills – demanding an extra volume of 19,000 m3 – reducing landfill lifespan, and hence causing a double loss: economic and environmental.

TOMOGRAPHIC CHARACTERISTIC OF MYXOMA IN THE ANTERIOR REGION OF THE MANDIBLE: A CASE DISCUSSION

This report presents a case of a 20-year-old female patient, forwarded by an orthodontist in April 2018. An extra-oral exam was taken; however, no face asymmetry was detected. A discrete extra volume in the apical region was found on the vestibular and lingual cortical teeth from 32 to 34, firm on palpation, and pain or paresthesia was reported by the patient. A computed tomography scan of the mandibular region was performed, in the axial sections, and hypodense images were observed with expansion of the vestibular cortex and presence of fine septa. The histopathologic examination showed characteristic of odontogenic myxoma. Based on the imaging and biopsional diagnosis, the patient was referred for surgical treatment, due to age and facial preservation. During the surgical procedure, marginal resection of the mandible and curettage were performed. The patient is in the postoperative period of 8 months with no complaints.

Advancing stereoisomeric separation of an atropisomeric Bruton's tyrosine kinase inhibitor by using sub-2µm immobilized polysaccharide-based chiral columns in supercritical fluid chromatography.

BMS-986142 is a Bruton's tyrosine kinase inhibitor under development to treat several disease types. The compound contains three chiral elements: one chiral center and two chiral axes, resulting in three potential atropisomeric impurities in its drug substance and drug products. Separation of BMS-986142 atropisomers has been successfully achieved on an achiral polar-embedded C18 column in reversed-phase liquid chromatography (RPLC) and on polysaccharide-based chiral columns in RPLC and supercritical fluid chromatography (SFC). Compared to the RPLC chiral separation, the SFC atropisomeric separation on a sub-2 μm immobilized cellulose-based column is much more efficient and environmentally friendly. The analysis time in SFC was reduced by 8-fold compared to that in RPLC, and the method sensitivity in SFC on the sub-2 μm chiral column in 3.0mm I.D. was 2 to 4-fold better than that on 3 μm chiral columns in 4.6mm I.D.. Furthermore, our study suggests that the contribution to band broadening from the extra column volume (ECV) of modern commercial SFC instrument was not negligible for a 3.0mm I.D.×100mm column packed with 1.6 μm particles. This result reaffirms that there is a great need for further improvement of SFC instrument design in order to realize the full theoretical efficiency of both sub-2 μm achiral and chiral columns.

Female foraging impairment related to reproduction in a neotropical spider

Females not only produce costly gametes, but also store the eggs until laying them, a period called gravidity. The volume that eggs occupy in the female abdomen may decrease female foraging ability by making them slower. Although females of all species are subjected to these potential costs, it remains an unexplored matter in invertebrates. Females of the spider Paratrechalea ornata carry their egg sac after oviposition and thus represent a unique opportunity to evaluate gravidity costs because females carry an extra volume before and after laying eggs. We conducted foraging ability experiments using P. ornata females on different treatments regarding gravidity and maternal care. We first hypothesized that internal egg load and egg sac carrying decrease female foraging ability. We also hypothesized that greater egg sac size decreases female foraging ability. We found that both internal egg load and egg sac carrying decreased female foraging ability, and females about to oviposit had a similar foraging ability to females carrying an egg sac. Egg sac size did not influence female foraging ability. Our results show that females’ foraging ability changes before the maternal care period and therefore may influence their life-history evolution. The little support for our second hypothesis may also suggest that the decrease in foraging ability is not due to the volume being carried per se, but possibly an associated physiological state.

Effects of severe-strain-induced defects on the mechanical response of two kinds of high-angle grain boundaries

ABSTRACT Grain boundaries of metallic materials subjected to severe plastic deformation exhibit significantly enhanced diffusivity and excess energy compared with their relaxed poly- or bi-crystalline counterparts even when the macroscopic degrees of freedom are the same in both types of grain boundaries. Boundaries of excess energy are/can be relaxed by annealing. As a first step in accounting for this experimentally observed high-energy state of general high-angle grain boundaries subjected to severe plastic deformation, a concept of localised basic shear units and the presence of localised extra free volume in these units situated in different locations in the grain boundaries, which was originally proposed to explain steady-state structural superplastic flow, is made use of. Using MD simulation, the mechanical response of these modified grain boundaries is compared with that of their relaxed state. The results are also compared with a case of a homogeneous distribution of extra free volume within the grain boundary. The localised shear units containing extra free volume introduced in the grain boundaries are found to alter their physical and mechanical features strongly, which, in turn, drastically affect, consistent with experimental results, the mechanical response of the heavily deformed material.

Design 5.0 µm Gap Aluminium Interdigitated Electrode for Sensitive pH Detection

The aim of the research study to design high sensitive biosensor for medical applications. IDE pattern was designed using AutoCAD software with 5 µm ginger gap. The fabrication process was done using a conventional photolithography process and standard CMOS process. The fabricated electrode was physically characterized using a low power microscope (LPM) and a high power microscope (HPM). The electrically validated through I-V measurements and chemically tested with different pH buffer solutions. Al IDE was well fabricated with 0.1 µm tolerance between the design mask and fabricated IDEs. Electrical measurements confirmed that IDE was well fabricated without any shortage and results of similar IDE samples were confirmed that the repeatability of the device. The extremely small current variations in nano ampere range were quantitatively detected using an extra small volume of 2 µl for different pH buffer solutions. It is confirmed that IDEs are sensitive in both alkali and hydroxyl ions medium.

Extracorporeal Life Support Organization (ELSO): Guidelines for Neonatal Respiratory Failure.

Extracorporeal Life Support Organization (ELSO): Guidelines for Neonatal Respiratory Failure.

A Simple Intervention to Decrease Nutrient Losses in Continuous Feeds With Human Milk.

Current evidence suggests that a significant amount of human milk fat is lost because of tubing adsorption. The objective was to evaluate the effect of reintroducing tubing leftover milk on the quality of macronutrient content of delivered milk. This was an in vitro study. The standard method of preparing and delivering fortified human milk includes preparing a small extra volume that would be used for priming the connection tubes. At the end of the infusion, the tubes and any milk leftover would be discarded. This method was compared with a new method where by the exact milk volume was prepared and used to prime the connection tubes. Leftover tubing milk was pushed with air. The standard method was associated with significant losses in fat, protein, and calories of 16.7%, 3.4%, and 9.2% compared with the new method of 8.2%, 0%, and 3.3%, respectively. These losses in the standard method were predominantly explained by the significant gains in the left over milk contents of fat 6.3 ± 1.1 g/dL, protein 3.5 ± 0.4 g/dL, and calories 28 ± 2.6 kcal/oz as compared with prepared milk of 4.8 ± 0.3, 2.9 ± 0.3 g/dL, and 24.0 ± 0.8 kcal/oz respectively, P = 0.002. Traditional continuous delivery methods of human milk are associated with significant losses of fat and protein. By preparing the exact amount of ordered milk and then pushing through the residual milk left in the tubing with a small amount of air, this study offers a simple intervention that would significantly decrease these losses.

Mutual promotion between aerosol particle liquid water and particulate nitrate enhancement leads to severe nitrate-dominated particulate matter pollution and low visibility

Abstract. As has been the case in North America and western Europe, the SO2 emissions have substantially reduced in the North China Plain (NCP) in recent years. Differential rates of reduction in SO2 and NOx concentrations result in the frequent occurrence of particulate matter pollution dominated by nitrate (pNO3-) over the NCP. In this study, we observed a polluted episode with the particulate nitrate mass fraction in nonrefractory PM1 (NR-PM1) being up to 44 % during wintertime in Beijing. Based on this typical pNO3--dominated haze event, the linkage between aerosol water uptake and pNO3- enhancement, further impacting on visibility degradation, has been investigated based on field observations and theoretical calculations. During haze development, as ambient relative humidity (RH) increased from ∼10 % to 70 %, the aerosol particle liquid water increased from ∼1 µg m−3 at the beginning to ∼75 µg m−3 in the fully developed haze period. The aerosol liquid water further increased the aerosol surface area and volume, enhancing the condensational loss of N2O5 over particles. From the beginning to the fully developed haze, the condensational loss of N2O5 increased by a factor of 20 when only considering aerosol surface area and volume of dry particles, while increasing by a factor of 25 when considering extra surface area and volume due to water uptake. Furthermore, aerosol liquid water favored the thermodynamic equilibrium of HNO3 in the particle phase under the supersaturated HNO3 and NH3 in the atmosphere. All the above results demonstrated that pNO3- is enhanced by aerosol water uptake with elevated ambient RH during haze development, in turn facilitating the aerosol take-up of water due to the hygroscopicity of particulate nitrate salt. Such mutual promotion between aerosol particle liquid water and particulate nitrate enhancement can rapidly degrade air quality and halve visibility within 1 d. Reduction of nitrogen-containing gaseous precursors, e.g., by control of traffic emissions, is essential in mitigating severe haze events in the NCP.

Pool boiling heat transfer intensification by electro-stimulation

In this investigation, a novel technique for intensification of pool boiling heat transfer coefficient has been proposed. This method is applicable to electrolyte aqueous solutions at the isolated bubble regime. This approach is based on stimulating heating surface by DC electricity. In this condition, boiling and electrolysis phenomena performs simultaneously. Decomposed hydrogen and oxygen blends to vaporized water during boiling and provides extra bubble volume; moreover, active nucleation sites increase on the heating surface. Consequently, bubble dynamics including frequency, diameter and active nucleation site density are significantly affected. In this investigation, two opposing consequence from modified bubble dynamics have been observed: (1) enhanced heat transfer up to 40% as a result of increased active nucleation site density, bubble diameter and frequency at some low voltages of electrolysis, and (2) reduced heat transfer down to 70% because of an interconnected clusters of hydrogen/water vapor mixture which are attached on the heating surface at some high voltages of electrolysis. The experimental data were analyzed by artificial neural network and sensitivity analysis have been performed. The impact of bulk and wall temperatures, also electrolysis and heat power flux on heat transfer rate have been determined by sensitivity analysis. Results present that maximum enhancement of heat transfer coefficient is observed at about 1 kW m−2 electrolysis power flux. At wall temperatures above 290 K, no enhancement is observed by increasing bulk temperatures. Enhancement requires minimum boiling heat flux of 45 kW m−2.

Alloying Element Segregation and Grain Boundary Reconstruction, Atomistic Modeling

Grain boundary (GB) segregation is an important phenomenon that affects many physical properties, as well as microstructure of polycrystals. The segregation of solute atoms on GBs and its effect on GB structure in Al were investigated using two approaches: First principles total energy calculations and the finite temperature large-scale atomistic modeling within hybrid MD/MC approach comprising molecular dynamics and Monte Carlo simulations. We show that the character of chemical bonding is essential in the solute–GB interaction, and that formation of directed quasi-covalent bonds between Si and Zn solutes and neighboring Al atoms causes a significant reconstruction of the GB structure involving a GB shear-migration coupling. For the solutes that are acceptors of electrons in the Al matrix and have a bigger atomic size (such as Mg), the preferred position is determined by the presence of extra volume at the GB and/or reduced number of the nearest neighbors; in this case, the symmetric GB keeps its structure. By using MD/MC approach, we found that GBs undergo significant structural reconstruction during segregation, which can involve the formation of single- or double-layer segregations, GB splitting, and coupled shear-migration, depending on the details of interatomic interactions.