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1.
Molecules ; 26(5)2021 Feb 25.
Artículo en Inglés | MEDLINE | ID: mdl-33668744

RESUMEN

Total scattering structure factors of per-deuterated methanol and heavy water, CD3OD and D2O, have been determined across the entire composition range as a function of pressure up to 1.2 GPa, by neutron diffraction. The largest variations due to increasing pressure were observed below a scattering variable value of 5 Å-1, mostly as shifts in terms of the positions of the first and second maxima. Molecular dynamics computer simulations, using combinations of all-atom potentials for methanol and various water force fields, were conducted at the experimental pressures with the aim of interpreting neutron diffraction results. The peak-position shifts mentioned above could be qualitatively reproduced by simulations, although in terms of peak intensities, the accord between neutron diffraction and molecular dynamics was much less satisfactory. However, bearing in mind that increasing pressure must have a profound effect on repulsive forces between neighboring molecules, the agreement between experiment and computer simulation can certainly be termed as satisfactory. In order to reveal the influence of changing pressure on local intermolecular structure in these "simplest of complex" hydrogen-bonded liquid mixtures, simulated structures were analyzed in terms of hydrogen bond-related partial radial distribution functions and size distributions of hydrogen-bonded cyclic entities. Distinct differences between pressure-dependent structures of water-rich and methanol-rich composition regions were revealed.


Asunto(s)
Óxido de Deuterio/química , Metanol/química , Simulación de Dinámica Molecular , Enlace de Hidrógeno , Estructura Molecular , Difracción de Neutrones , Presión
2.
Sensors (Basel) ; 21(4)2021 Feb 19.
Artículo en Inglés | MEDLINE | ID: mdl-33669674

RESUMEN

The quantification of plantar pressure distribution is widely done in the diagnosis of lower limbs deformities, gait analysis, footwear design, and sport applications. To date, a number of pressure insole layouts have been proposed, with different configurations according to their applications. The goal of this study is to assess the validity of a 16-sensors (1.5 × 1.5 cm) pressure insole to detect plantar pressure distribution during different tasks in the clinic and sport domains. The data of 39 healthy adults, acquired with a Pedar-X® system (Novel GmbH, Munich, Germany) during walking, weight lifting, and drop landing, were used to simulate the insole. The sensors were distributed by considering the location of the peak pressure on all trials: 4 on the hindfoot, 3 on the midfoot, and 9 on the forefoot. The following variables were computed with both systems and compared by estimating the Root Mean Square Error (RMSE): Peak/Mean Pressure, Ground Reaction Force (GRF), Center of Pressure (COP), the distance between COP and the origin, the Contact Area. The lowest (0.61%) and highest (82.4%) RMSE values were detected during gait on the medial-lateral COP and the GRF, respectively. This approach could be used for testing different layouts on various applications prior to production.


Asunto(s)
Zapatos , Caminata , Adulto , Fenómenos Biomecánicos , Marcha , Alemania , Humanos , Proyectos Piloto , Presión , Dispositivos Electrónicos Vestibles
3.
Sensors (Basel) ; 21(4)2021 Feb 11.
Artículo en Inglés | MEDLINE | ID: mdl-33670238

RESUMEN

(1) Background: Postural sway is frequently used to quantify human postural control, balance, injury, and neurological deficits. However, there is considerably less research investigating the value of the metric in horses. Much of the existing equine postural sway research uses force or pressure plates to examine the centre of pressure, inferring change at the centre of mass (COM). This study looks at the inverse, using an inertial measurement unit (IMU) on the withers to investigate change at the COM, exploring the potential of postural sway evaluation in the applied domain. (2) Methods: The lipopolysaccharide model was used to induce transient bilateral lameness in seven equines. Horses were monitored intermittently by a withers fixed IMU over seven days. (3) Results: There was a significant effect of time on total protein, carpal circumference, and white blood cell count in the horses, indicating the presence of, and recovery from, inflammation. There was a greater amplitude of displacement in the craniocaudal (CC) versus the mediolateral (ML) direction. A significant difference was observed in the amplitude of displacement in the ML direction between 4-12 h and 168 h. (4) Conclusions: The significant reduction in ML displacement during the acute inflammation period alongside greater overall CC displacement may be a compensatory behaviour for bilateral lameness.


Asunto(s)
Caballos , Cojera Animal/diagnóstico , Equilibrio Postural , Animales , Estudios de Factibilidad , Cojera Animal/inducido químicamente , Presión , Torso
4.
Waste Manag ; 125: 316-327, 2021 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-33725517

RESUMEN

Low bulk density, variable moisture content, and particle size of municipal solid waste (MSW) create feeding, handling, storage, and transportation challenges. In this study, MSW bales were size-reduced in stage-1 and stage-2 hammer mill grinders fitted with 50.8-mm and 6.35-, 12.7-, and 19.05-mm screens. Ground MSW was densified further in a pilot-scale briquette press by varying moisture content in the range of 10-25% wet basis (w.b.). At 40% (w.b.) MSW moisture content, the stage-1 grinder fitted with a 50.4-mm screen took about 136kWh/ton, while the stage-2 grinder fitted with a 19.05-mm screen took about 151kWh/ton. The bulk density of MSW after stage-1 and stage-2 grinding was about 25-50 kg/m3. Unit bulk and tapped density were in the range of 680-850 kg/m3, 478-315 kg/m3, and 346-540 kg/m3 post briquetting, and 591-830 kg/m3, 295-458 kg/m3, and 319-519 kg/m3 post five days of storage at 20 °C. The durability was about 93.40-98.54% post briquetting, and after five days of storage. Increasing the moisture content and screen size decreased density and improved durability. Briquetting energy increased to 120 kWh/ton at a higher moisture content and larger grind size. MSW flow characteristics improved after briquetting. Higher lignin content (≈30%) and calorific value (19-21 MJ/kg) suggest MSW is suitable for thermochemical conversion. Ash content in the MSW was in the 11.9-14.8% range. CT-scan images of the briquettes showed a network of interconnected pores formed due to compression of various MSW fractions.


Asunto(s)
Eliminación de Residuos , Residuos Sólidos , Presión , Residuos Sólidos/análisis
5.
Biomed Eng Online ; 20(1): 30, 2021 Mar 25.
Artículo en Inglés | MEDLINE | ID: mdl-33766034

RESUMEN

BACKGROUND: The regulation and control of pressure stimuli is useful for many studies of pain and nociception especially those in the visceral pain field. In many in vivo experiments, distinct air and liquid stimuli at varying pressures are delivered to hollow organs such as the bladder, vagina, and colon. These stimuli are coupled with behavioral, molecular, or physiological read-outs of the response to the stimulus. Care must be taken to deliver precise timed stimuli during experimentation. For example, stimuli signals can be used online to precisely time-lock the stimulus with a physiological output. Such precision requires the development of specialized hardware to control the stimulus (e.g., air) while providing a precise read-out of pressure and stimulus signal markers. METHODS: In this study, we designed a timed pressure regulator [termed visceral pressure stimulator (VPS)] to control air flow, measure pressure (in mmHg), and send stimuli markers to online software. The device was built using a simple circuit and primarily off-the-shelf parts. A separate custom inline analog-to-digital pressure converter was used to validate the real pressure output of the VPS. RESULTS: Using commercial physiological software (Spike2, CED), we were able to measure mouse bladder pressure continuously during delivery of unique air stimulus trials in a mouse while simultaneously recording an electromyogram (EMG) of the overlying abdominal muscles. CONCLUSIONS: This device will be useful for those who need to (1) deliver distinct pressure stimuli while (2) measuring the pressure in real-time and (3) monitoring stimulus on-off using physiological software.


Asunto(s)
Colon/diagnóstico por imagen , Electromiografía , Vejiga Urinaria/diagnóstico por imagen , Vagina/diagnóstico por imagen , Animales , Femenino , Ratones , Proyectos Piloto , Presión , Procesamiento de Señales Asistido por Computador , Programas Informáticos , Dolor Visceral
6.
Food Chem ; 352: 129410, 2021 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-33677210

RESUMEN

The purpose of this exploration was to determine the density and volumetric properties of the aqueous solution of Na2H2P2O7 with the molality varied from 0.08706 to 0.88402 mol·kg-1 measured at temperature intervals of 5 K from 283.15 to 363.15 K at 101.325 kPa using Anton Paar Digital vibrating-tube densimeter. The thermal expansion coefficient (α), apparent molar volume (VΦ), expansibility (ϕE), and partial molar volume (VB) of Na2H2P2O7 (aq) against temperature and molality have been evaluated from density data. On the basis of Pitzer ion-interaction apparent molar volume theory, the Pitzer single-salt parameters (ßM,X0v, ßM,X1v, ßM,X2v and CM,Xv, MX = Na2H2P2O7), and their correlation coefficients ai of the temperature-dependence formula f (i, p, T) = a1 + a2ln(T/298.15) + a3(T - 298.15) + a4/(620 - T) + a5/(T - 227) for Na2H2P2O7 were obtained for the first time. It was revealed that predicted apparent molar volumes agreed well with the experimental values indicating the single salt parameters and the temperature-dependent formula are reliable.


Asunto(s)
Difosfatos/química , Temperatura , Agua/química , Presión , Soluciones
7.
Carbohydr Polym ; 260: 117823, 2021 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-33712164

RESUMEN

A bio-based pressure-responsive sensor with adjustable structural color is prepared by combining aerogel skeleton of cellulose nanocrystals (CNCs)/poly(ethylene glycol) (PEG) obtained via the ice-templating method with flexible polyacrylamide (PAAM) elastomer. The white aerogel is composed of consecutive ribbons, demonstrating chiral nematic structure. These ribbons are rearranged to be vertical to the force direction, leading to immediate appearance of the structural color when the 3D aerogel transforms to a 2D plane. Helical pitches are regulated by the PEG content that the wavelength of structural color covers up to 178 nm. There is an excellent linear correlation between pressure and transmittance of reflectance peak, and the sensitivity to pressure can be regulated by changing solid content of PAAM. Furthermore, the pressure-responsive color is still vivid after 16 cycles of compression. This flexible material with pressure-responsive structural color is promising in sensing, intelligent display, information transmission, and etc.


Asunto(s)
Técnicas Biosensibles/métodos , Geles/química , Presión , Resinas Acrílicas/química , Celulosa/química , Fuerza Compresiva , Nanopartículas/química , Polietilenglicoles/química
8.
J Spec Oper Med ; 21(1): 11-17, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33721300

RESUMEN

BACKGROUND: Limb position changes are likely during transport from injury location to definitive care. This study investigated passive limb position change effects on tourniquet pressure and occlusion. METHODS: Triplicate buddy-applied OMNA® Marine Tourniquet applications to Doppler-based occlusion were done to sitting and laying supine mid-thigh (n=5) and sitting mid-arm (n=3). Tourniqueted limb positions were bent/straight/bent and straight/bent/straight (randomized first position order, 5 seconds/position, pressure every 0.1 second, two-way repeated measures ANOVA). RESULTS: Sitting thigh occlusion pressures leg bent were higher than straight (median, minimum-maximum; 328, 307-403mmHg versus 312, 295-387mmHg, p = .013). In each recipient, the pressure change for each position change for each limb had p < .003. In each recipient, when sitting, leg bent to straight increased pressure (326, 276-415mmHg to 371, 308-427mmHg bent first and 275, 233-354mmHg to 311, 241-353mmHg straight first), and straight to bent decreased pressure (371, 308-427mmHg to 301, 262-388mmHg bent first and 312, 265-395mmHg to 275, 233-354mmHg straight first). When laying, position changes from leg bent first resulted in pressure changes in each recipient but not in the same directions in each recipient. From laying leg straight first, in each recipient changing to bent increased the pressure (295, 210-366mmHg to 328, 255-376mmHg) and to straight decreased the pressure (328, 255-376 mmHg to 259, 210-333 mmHg). Sitting arm bent occlusion pressures were lower than straight (230, 228-252mmHg versus 256, 250-287mmHg, p = .026). Arm position changes resulted in pressure changes in each recipient but not in the same directions in each recipient. Changes in pressure trace character (presence or absence of rhythmically pulsatile traces) and Doppler-based occlusion were consistent with limb position-induced changes in tourniquet pressure (each p ≤ .001 leg, p = .071 arm traces, and p = .188 arm occlusion). CONCLUSIONS: Passive limb position changes can cause significant changes in tourniquet pressure. Therefore, tourniquet adequacy should be reassessed after any limb position change.


Asunto(s)
Muslo , Torniquetes , Presión , Ultrasonografía Doppler
10.
Zhongguo Gu Shang ; 34(3): 243-8, 2021 Mar 25.
Artículo en Chino | MEDLINE | ID: mdl-33787169

RESUMEN

OBJECTIVE: To compared with the modified Robert Jones bandage of 3M elastic bandage, to evaluate the fitness, convenience, safety and comfort of the modular combination lower limb elastic compression device. METHODS: Forty healthy adult college students, including 28 males and 12 females, aged 16 to 25 (20.3±2.2) years old and weighing 40 to 81 (60.4±20.2) kg, were randomly divided into two groups with 40 samples in each group. According to the body surface parameters of Chinese lower limbs and guided by the concept of modularization, a group of modular combined lower limb elastic compression device was designed. Each module was combined to evaluate the fitness of the modular combined compression device in thelength and circumference of the lower limbs. The left and right lower limbs were randomly paired and divided into groups, with 40 samples in each group. The convenience of the operation time, adjustment times and required time were compared between two groups. The safety of the two groups after 24 hours of application of pressure injury was compared. The subjective pain feeling changes within 24 hours were recorded by visual analogue scale (VAS) to evaluate the comfort. RESULTS: The device was composed of several elastic compression outer lining modules with different length and width of 15 cm, an inner lining module for buffering, positioning and attaching the main body, and an elastic ankle compression module. The length of the elastic compression outer lining module covers the circumference of the human lower limbs. The length of a single outer lining module increased from 15 cm to 80 cm every 5 cm interval, and the length of a single inner lining module increased from 62 cm to 83 cm every 3 cm interval. After the modules were selected and combined, the length and circumference of the lower limbs can reach 100% fitness. The operation time of the first placement(118.23±7.33) s and re operation(60.08±5.88) s of experimental group were significantly shorter than those of control group (164.68±8.93) s and re operation (131.23±7.91) s. The adjustment times (3) and operation time (3.50±0.71) s of experimental group were significantly shorter than those of control group(11)and operation time(139.00±5.66) s (P<0.05), but there was no significant difference between two groups (P>0.05). The VAS score of experimental group was significantly lower than that of control group at each time point (P<0.01). CONCLUSION: The modular combined elastic compression device has good fitness, better placement and flexible adjustment, convenience and safety, and better comfort than modified Robert Jones bandage of 3M elastic bandage.


Asunto(s)
Vendajes de Compresión , Extremidad Inferior , Adolescente , Adulto , Femenino , Humanos , Masculino , Dimensión del Dolor , Presión , Resultado del Tratamiento , Adulto Joven
11.
Food Chem ; 345: 128771, 2021 May 30.
Artículo en Inglés | MEDLINE | ID: mdl-33601652

RESUMEN

The isothiocyanate sulforaphane (SF) is one of the most potent naturally occurring Phase 2 enzymes inducers derived from brassica vegetables like broccoli, cabbage, brussel sprouts, etc. Ingestion of broccoli releases SF via hydrolysis of glucoraphanin (GRP) by plant myrosinase and/or intestinal microbiota. However, both SF and plant myrosinase are thermal-labile, and the epithiospecifier protein (ESP) directs the hydrolysis of GRP toward formation of sulforaphane nitrile instead of SF. In addition, bacterial myrosinase has low hydrolyzing efficiency. In this review, we discuss strategies that could be employed to improve the stability of SF, increase SF formation during thermal and non-thermal processing of broccoli, and enhance the myrosinase-like activity of the gut microbiota. Furthermore, new cooking methods or blanching technologies should be developed to maintain myrosinase activity, and novel thermostable myrosinase and/or microbes with high SF producing abilities should also be developed.


Asunto(s)
Brassica/química , Isotiocianatos/metabolismo , Bacterias/enzimología , Proteínas Bacterianas/metabolismo , Brassica/metabolismo , Culinaria , Estabilidad de Medicamentos , Glucosinolatos/química , Glucosinolatos/metabolismo , Glicósido Hidrolasas/metabolismo , Hidrólisis , Imidoésteres/química , Imidoésteres/metabolismo , Isotiocianatos/química , Presión
12.
J Laryngol Otol ; 135(2): 153-158, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33551000

RESUMEN

BACKGROUND: Transoral robotic surgery is frequently described, driven by the desire to offer a less morbid alternative to chemoradiation. However, the objective evaluation of post-operative function has rarely been reported. Therefore, high-resolution manometry was used in this study to evaluate the impact of changes in peri-operative swallowing function on pharyngeal pressure events. METHODS: Ten patients with various stages of oropharyngeal cancer underwent transoral surgery. High-resolution manometry and videofluoroscopic swallow studies were performed before surgery and two months afterwards. The following parameters were obtained: velopharyngeal and mesopharyngeal post-deglutitive upper oesophageal sphincter pressures, velo-meso-hypopharyngeal contractile integral, upper oesophageal sphincter relaxation pressure, and pharyngeal velocity. RESULTS: There was no significant difference in pharyngeal pressure or contractile integral pre- versus post-operatively. However, pharyngeal velocity was significantly higher post-operatively than pre-operatively. CONCLUSION: High-resolution manometry showed that transoral surgery in patients without pre-operative dysphagia preserved pharyngeal constriction. However, transoral surgery might produce scar formation in the pharynx, which could lead to narrowing of the pharynx.


Asunto(s)
Deglución/fisiología , Neoplasias Orofaríngeas/cirugía , Faringe/fisiopatología , Procedimientos Quirúrgicos Robotizados/efectos adversos , Anciano , Anciano de 80 o más Años , Trastornos de Deglución/fisiopatología , Esfínter Esofágico Superior/fisiología , Femenino , Humanos , Masculino , Manometría/métodos , Persona de Mediana Edad , Contracción Muscular/fisiología , Estadificación de Neoplasias , Neoplasias Orofaríngeas/patología , Periodo Posoperatorio , Presión , Procedimientos Quirúrgicos Robotizados/métodos , Carcinoma de Células Escamosas de Cabeza y Cuello/epidemiología , Carcinoma de Células Escamosas de Cabeza y Cuello/patología , Carcinoma de Células Escamosas de Cabeza y Cuello/cirugía
13.
J Vis Exp ; (168)2021 02 02.
Artículo en Inglés | MEDLINE | ID: mdl-33616116

RESUMEN

Lung histology is often used to investigate the contributions provided by airspace cells during lung homeostasis and disease pathogenesis. However, commonly used instillation-based fixation methods can displace airspace cells and mucus into terminal airways and can alter tissue morphology. In comparison, vascular perfusion-fixation techniques are superior at preserving the location and morphology of cells within airspaces and the mucosal lining. However, if positive airway pressure is not simultaneously applied, regions of the lungs may collapse and capillaries may bulge into the alveolar spaces, leading to distortion of the lung anatomy. Herein, we describe an inexpensive method for air-inflation during vascular perfusion-fixation to preserve the morphology and location of airway and alveolar cells and interstitium in murine lungs for downstream histologic studies. Constant air pressure is delivered to the lungs via the trachea from a sealed, air-filled chamber that maintains pressure via an adjustable liquid column while fixative is perfused through the right ventricle.


Asunto(s)
Vasos Sanguíneos/fisiología , Pulmón/fisiología , Perfusión , Presión , Alveolos Pulmonares/fisiología , Animales , Fijadores , Ratones
14.
J Chromatogr A ; 1641: 461971, 2021 Mar 29.
Artículo en Inglés | MEDLINE | ID: mdl-33626439

RESUMEN

N'-nitrosonornicotine (NNN) is one of the most prevalent and toxic tobacco-specific nitrosoamines. A chiral center at its 2'-position results in R and S enantiomers, the partial double bond character of the NN = O group also results in E and Z isomers, therefore, NNN can form a total of four absolute configurations (E-(R)-NNN, E-(S)-NNN, Z-(R)-NNN, and Z-(S)-NNN). This study investigated the resolution of R/S enantiomers and E/Z isomers of NNN by supercritical fluid chromatography tandem mass spectrometry (SFC-MS/MS). The baseline separation of E/Z-(R,S)-NNN isomers/enantiomers was accomplished through the optimization of chiral columns and co-solvents. Due to the lack of single standard of E/Z isomers, only R-NNN (sum of E-(R)-NNN and Z-(R)-NNN) and S-NNN (sum of E-(S)-NNN and Z-(S)-NNN) were further examined. Through the comprehensive optimization of SFC-MS/MS conditions, R-NNN and S-NNN were separated with a run time of 5 min, the developed method was validated, and its applicability to the determination of NNN enantiomers in burley tobacco samples was demonstrated. This study could be applied to preparative separation of single enantiomer and/or isomer of NNN, and could provide potential benefits to biologic activity studies on these enantiomers and isomers.


Asunto(s)
Cromatografía con Fluido Supercrítico/métodos , Nitrosaminas/química , Nitrosaminas/aislamiento & purificación , Espectrometría de Masas en Tándem/métodos , Metanol/química , Presión , Reproducibilidad de los Resultados , Estereoisomerismo , Temperatura , Tabaco/química
15.
Biophys J ; 120(6): 1105-1119, 2021 03 16.
Artículo en Inglés | MEDLINE | ID: mdl-33631204

RESUMEN

Cell penetration after recognition of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus by the ACE2 receptor and the fusion of its viral envelope membrane with cellular membranes are the early steps of infectivity. A region of the Spike protein of the virus, identified as the "fusion peptide" (FP), is liberated at its N-terminal site by a specific cleavage occurring in concert with the interaction of the receptor-binding domain of the Spike. Studies have shown that penetration is enhanced by the required binding of Ca2+ ions to the FPs of coronaviruses, but the mechanisms of membrane insertion and destabilization remain unclear. We have predicted the preferred positions of Ca2+ binding to the SARS-CoV-2-FP, the role of Ca2+ ions in mediating peptide-membrane interactions, the preferred mode of insertion of the Ca2+-bound SARS-CoV-2-FP, and consequent effects on the lipid bilayer from extensive atomistic molecular dynamics simulations and trajectory analyses. In a systematic sampling of the interactions of the Ca2+-bound peptide models with lipid membranes, SARS-CoV-2-FP penetrated the bilayer and disrupted its organization only in two modes involving different structural domains. In one, the hydrophobic residues F833/I834 from the middle region of the peptide are inserted. In the other, more prevalent mode, the penetration involves residues L822/F823 from the LLF motif, which is conserved in CoV-2-like viruses, and is achieved by the binding of Ca2+ ions to the D830/D839 and E819/D820 residue pairs. FP penetration is shown to modify the molecular organization in specific areas of the bilayer, and the extent of membrane binding of the SARS-CoV-2 FP is significantly reduced in the absence of Ca2+ ions. These findings provide novel mechanistic insights regarding the role of Ca2+ in mediating SARS-CoV-2 fusion and provide a detailed structural platform to aid the ongoing efforts in rational design of compounds to inhibit SARS-CoV-2 cell entry.


Asunto(s)
Calcio/metabolismo , Membrana Celular/metabolismo , Proteínas Recombinantes de Fusión/metabolismo , /metabolismo , Secuencia de Aminoácidos , Permeabilidad de la Membrana Celular , Lípidos de la Membrana/química , Simulación de Dinámica Molecular , Presión , Probabilidad , Estabilidad Proteica , Proteínas Recombinantes de Fusión/química , Agua/química
16.
Water Sci Technol ; 83(4): 771-780, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33617485

RESUMEN

Rapid filling in horizontal partially filled pipes with entrapped air may result in extreme pressure transients. This study advanced the current understanding of dynamic behavior of entrapped air above tailwater (the initial water column with a free surface in a partially filled pipe) through rigid-column modeling and sensitivity analysis of system parameters. Water and air were considered as incompressible fluid and ideal gas, respectively, and the continuity and momentum equations for water and a thermodynamic equation for air were solved by using the fourth order Runge-Kutta method. The effects of system parameters were examined in detail, including tailwater depth, entrapped air volume, driving head, pipe friction, and relative length of entrapped air and pipe. The results indicate that the presence of tailwater can mitigate the peak pressure when with identical initial volumes of entrapped air, as it can be considered to reflect a certain amount of loss of the net driving head. However, the peak pressure can increase as much as about 45% for the cases with fixed pipe length, due to the reduction in the initial entrapped air volume. The rise time for the first peak pressure was closely related to pipe friction, whereas the oscillation period (defined as the time duration between the first and second peaks) was virtually irrelevant. The applicability of the rigid-column model was discussed, and a time scale relevant indicator was proposed. When the indicator is larger than 20, the relative difference between the peak pressure estimation and experimental measurements is generally below 5%.


Asunto(s)
Modelos Teóricos , Movimientos del Agua , Fricción , Presión , Agua
17.
BMJ Open ; 11(2): e041880, 2021 02 18.
Artículo en Inglés | MEDLINE | ID: mdl-33602704

RESUMEN

OBJECTIVES: To explore the association between N95 respirator wearing and device-related pressure injury (DRPI) and to provide a basis for protecting medical staff from skin injuries. DESIGN: A cross-sectional, multicentre study. SETTING AND PARTICIPANTS: Medical staff of 60 hospitals were selected from 145 designated medical institutions located in the epidemic area where the patients with COVID-19 were treated in China. RESULTS: In total, 1761 respondents wore N95 respirators (use alone 20.8%; combination use 79.2%), and the prevalence of DRPI was 59.2% (95% CI 56.93 to 61.53). A daily wearing time of >4 hours (OR 1.62, 95% CI 1.11 to 2.35), wearing a N95 respirator in combination with goggles both with the presence of sweating (OR 13.40, 95% CI 7.34 to 23.16) and without the presence of sweating (OR 0.80, 95% CI 0.56 to 1.14) and wearing only a N95 respirator with the presence of sweating (OR 9.60, 95% CI 7.00 to 13.16) were associated with DRPI. A correspondence analysis indicated that if there was no sweating, regardless of whether the N95 respirator was worn by itself or in combination with goggles, single-site DRPI mainly occurred on the nose bridge, cheek and auricle. If there was sweating present, regardless of whether the N95 was worn by itself or in combination with goggles, multiple DRPI sites occurred more often on the face. CONCLUSIONS: The prevalence of DRPI among medical staff caused by N95 respirators was very high, which was mainly associated with a longer daily wearing time and interaction with sweating. The nasal bridge, cheeks and auricles were the primary protection locations found.


Asunto(s)
/prevención & control , Exposición Profesional/prevención & control , Traumatismos Ocupacionales/epidemiología , Adulto , China/epidemiología , Estudios Transversales , Femenino , Humanos , Masculino , Presión , Sudoración
18.
J Vis Exp ; (167)2021 01 18.
Artículo en Inglés | MEDLINE | ID: mdl-33522513

RESUMEN

A technique to improve the combustion performance of a hybrid rocket engine using a novel fuel grain structure is presented. This technique utilizes the different regression rates of acrylonitrile butadiene styrene and paraffin-based fuels, which increase the exchanges of both matter and energy by swirl flow and recirculation zones formed at the grooves between the adjacent vanes. The centrifugal casting technique is used to cast the paraffin-based fuel into an acrylonitrile butadiene styrene substrate made by three-dimensional printing. Using oxygen as the oxidizer, a series of tests were conducted to investigate the combustion performance of the novel fuel grain. In comparison to paraffin-based fuel grains, the fuel grain with a nested helical structure, which can be maintained throughout the combustion process, showed significant improvement in the regression rate and great potential in improvement of combustion efficiency.


Asunto(s)
Gasolina/análisis , Nave Espacial , Oxígeno/química , Parafina/química , Presión , Análisis de Regresión , Reología , Emisiones de Vehículos
19.
BMC Pulm Med ; 21(1): 62, 2021 Feb 22.
Artículo en Inglés | MEDLINE | ID: mdl-33618696

RESUMEN

BACKGROUND: The most important target cell of SARS-CoV-2 is Type II pneumocyte which produces and secretes pulmonary surfactant (PS) that prevents alveolar collapse. PS instillation therapy is dramatically effective for infant respiratory distress syndrome but has been clinically ineffective for ARDS. Nowadays, ARDS is regarded as non-cardiogenic pulmonary edema with vascular hyper-permeability regardless of direct relation to PS dysfunction. However, there is a possibility that this ineffectiveness of PS instillation for ARDS is caused by insufficient delivery. Then, we performed PS instillation simulation with realistic human airway models by the use of computational fluid dynamics, and investigated how instilled PS would move in the liquid layer covering the airway wall and reach to alveolar regions. METHODS: Two types of 3D human airway models were prepared: one was from the trachea to the lobular bronchi and the other was from a subsegmental bronchus to respiratory bronchioles. The thickness of the liquid layer covering the airway was assigned as 14 % of the inner radius of the airway segment. The liquid layer was assumed to be replaced by an instilled PS. The flow rate of the instilled PS was assigned a constant value, which was determined by the total amount and instillation time in clinical use. The PS concentration of the liquid layer during instillation was computed by solving the advective-diffusion equation. RESULTS: The driving pressure from the trachea to respiratory bronchioles was calculated at 317 cmH2O, which is about 20 times of a standard value in conventional PS instillation method where the driving pressure was given by difference between inspiratory and end-expiratory pressures of a ventilator. It means that almost all PS does not reach the alveolar regions but moves to and fro within the airway according to the change in ventilator pressure. The driving pressure from subsegmental bronchus was calculated at 273 cm H2O, that is clinically possible by wedge instillation under bronchoscopic observation. CONCLUSIONS: The simulation study has revealed that selective wedge instillation under bronchoscopic observation should be tried for COVID-19 pneumonia before the onset of ARDS. It will be also useful for preventing secondary lung fibrosis.


Asunto(s)
Bronquios/fisiología , Bronquiolos/fisiología , Simulación por Computador , Hidrodinámica , Presión , Surfactantes Pulmonares/administración & dosificación , Tráquea/fisiología , Broncoscopía , Humanos , Instilación de Medicamentos , Respiración Artificial
20.
Nihon Ronen Igakkai Zasshi ; 58(1): 134-142, 2021.
Artículo en Japonés | MEDLINE | ID: mdl-33627550

RESUMEN

PURPOSE: It is important to prevent sarcopenia in community-dwelling elderly adults. Thus, we investigated the relationship between the swallowing function, nutritional status, and physical function in elderly outpatients. METHODS: A total of 90 elderly outpatients (77.2±8.3 years) participated in the study. The investigation items included the Seirei dysphagia screening questionnaire, 20 masticable foods questionnaire, tongue pressure, grip strength, the skeletal muscle mass index (SMI), the questionnaire for sarcopenia screening (SARC-F), and the Mini Nutritional Assessment-Short Form (MNA-SF). The odds ratio for the swallowing function and six items was determined by a logistic regression analysis. RESULTS: About 83.3% of the participants were at risk of dysphagia. The questions that detected the symptom in ≥30% of the participants were, "Do you cough during a meal?", "Have you become slower at eating?", and "Has it become more difficult to eat hard food?". The 20 masticable foods questionnaire, SARC-F, and MNA-SF were correlated with the Seirei dysphagia screening questionnaire. The results of the logistic regression analysis indicated that SARC-F was a significant predictor for a loss of the swallowing function. CONCLUSION: Because elderly outpatients have a decreased oral function, including chewing, they are at an increased risk of dysphagia. This study suggested that the swallowing function in elderly outpatients is related to the chewing ability, nutritional status, and sarcopenia. The swallowing function can thus be used to detect sarcopenia in elderly outpatients at an early stage and is important for preventing dysphagia.


Asunto(s)
Deglución , Sarcopenia , Anciano , Evaluación Geriátrica , Humanos , Estado Nutricional , Pacientes Ambulatorios , Presión , Sarcopenia/diagnóstico , Lengua
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