Negative Pressure Method Research Articles

An epoxy resin-based superhydrophobic coating incorporating pH-responsive functional multiwall carbon nanotubes assembled L-proline for corrosion protection

Purpose This paper aims to improve the corrosion resistance of AH36 carbon steel, an epoxy resin (EP)-based superhydrophobic coating was prepared on the surface of AH36 carbon steel. Design/methodology/approach The hydroxylated multi-walled carbon nanotubes were used as nanocontainers, and the corrosion inhibitor L-proline was loaded by negative pressure method and then modified it with 3-aminopropyltriethoxysilane and 3-mercaptopropyltrimethoxysilane, got functionalized hydroxy carbon nanotubes (KH-CNTs@LP). The KH-CNTs@LP was mixed with the EP, and the KH-CNTs@LP/EP superhydrophobic coating was successfully prepared on the surface of the AH36 carbon steel matrix by spraying. Findings The results showed that the water contact angle of the KH-CNTs@LP/EP superhydrophobic coating is 155.2° and the rolling angle is 5°. The KH-CNTs@LP/EP superhydrophobic coating had a good corrosion resistance in the pH = 4 corrosion environment, |Z|0.01 Hz was 7.21 × 107 Ω·cm2. Originality/value The KH-CNTs@LP/EP superhydrophobic coating is pH-responsive and releases L-proline, which increased the impedance of the coating and can effectively improve the protection efficiency of the coating on the metal. The active protection is provided by loaded L-proline inhibitor from KH-CNTs@LP, whereas the passive protection is achieved through the water rejection of superhydrophobic surfaces.

Measurement of inward leakage of full-face masks in EN and ISO standards: comparison of gas and aerosol test agents.

In Europe, respiratory protective devices must be certified before they can be marketed. Among the parameters of interest, inward leakage (IL) characterizes the tightness between the face seal and the face, to verify that the device is well-designed. European standard EN 13274-1 (2001) and International Organization for Standardization (ISO) standard ISO 16900-1 (2019) specify that IL should be measured using sodium chloride (NaCl) aerosol or sulfur hexafluoride (SF6) gas. For reusable masks made of nonporous materials, both test agents are considered equally acceptable. However, the few studies that have compared IL values measured with various aerosols and gases have come to divergent conclusions. This work then aimed to measure IL with the test agents recommended by the standards to determine whether they are really equivalent. Since krypton (Kr) is an interesting candidate for replacing SF6 in standard tests, IL was assessed with SF6 and Kr simultaneously, and with NaCl aerosol using various calculation methods. Tests were carried out on 5 models of full-face masks donned on a headform connected to a breathing machine simulating 3 sinusoidal breathing rates of various intensities. The respirator fit on the headform was evaluated using a controlled negative pressure method to determine a manikin fit factor. Four scenarios were then tested to represent very poor, bad, good, and excellent fit. Gas concentration was measured using a mass spectrometer, and IL was calculated for SF6 and Kr. A combination of 3 devices allowed the determination of the number-based concentration of particles with diameters between 20 nm and 2 µm, and IL was calculated for each of the 33 channels, as well as using a cumulative number concentration. In addition, to comply with standards, a conversion was carried out to calculate IL using a cumulative mass concentration. The results of this work evidenced that the IL values measured with NaCl were systematically lower than those determined with gases. IL was also shown to vary with particle size, with a maximum value exceeding that calculated with cumulative concentrations (in number or mass). As part of the revision of the standards, protocols for measuring inward leakage should be redefined. On the one hand, acceptability thresholds should be re-evaluated according to the nature of the test agent (gas or aerosol), as it is clear that the 2 options do not give the same results for a given configuration. On the other hand, the aerosol leakage measurement protocol needs to be reworked to enable the measurement of a well-defined, robust, and reproducible inward leakage value.

Fe3O4@MBT composite inhibitor for magnetic field sensitive controlled release and corrosion inhibition

Hollow porous Fe3O4 microspheres were prepared by citrate-assisted solvothermal method and used as nanocarrier, and then the 2-Mercaptobenzothiazole (MBT) inhibitor was encapsulated into the interior of Fe3O4 nanoparticles via vacuum negative pressure method. The results show that the obtained Fe3O4@MBT nanocomposite inhibitor has a MBT loading capacity of 13.831 % and saturation magnetization of 68.7 emu·g−1. Release study reveals the release of MBT inhibitor from the nanocomposites is mainly Fickian diffusion and diffusion among magnetic particles. The external magnetic field (MF) would effectively delay the release of inhibitor by increasing diffusion difficulty among magnetic particles. Additionally, the Fe3O4@MBT has an excellent inhibition effect for carbon steel, and the inhibition behavior can be regulated by MF.

The new insights towards smart pH-responsive anticorrosion coating based on HNTs carrying synergistic inhibitors: Experimental and molecular simulation

Corrosion of steel structures in reinforced concrete structures in coastal areas has long been an urgent concern. In this study, a combined corrosion inhibitor, consisting of benzotriazole (BTA) and sodium D-gluconate (SD), was loaded onto halloysite nanotubes (HNTs) using the vacuum negative pressure method. Then, the HNTs were encapsulated with biomass polyelectrolytes sodium alginate (SA) and chitosan (CS) by layer-by-layer self-assembly technique to prepare BTA/SD-HNTs@CS/SA (FHNTs) composite. Furtherly, a functional epoxy coating (FEP) with pH-responsive and long-term service ability was successfully fabricated. It is found that BTA/SD was released in large quantities under alkaline (pH = 11) and acidic (pH = 2) conditions, while essentially no release under neutral condition. The electrochemical impedance spectroscopy (EIS) measurements demonstrate that the corrosion protection ability of FEP was significantly stronger than pure epoxy coating (EP), and the addition of 2 % FHNTs having the most excellent anticorrosion performance with the maximum charge transfer resistance (Rct) value (4.8 × 106 Ω cm2) after 4 weeks of immersion, which was 2 orders of magnitude greater than the pure EP coating. Particularly, molecular dynamics (MD) simulations indicate that FEP coating has better barrier properties than EP, while the fractional free volume (FFV) value of H2O and Cl− in EP was 9.1 % and 5.1 %, respectively, whereas this value decreased by about 15 % to 7.7 % and 4.4 % in FEP. The results of density functional theory (DFT) calculations suggest that the released BTA and SD molecules have a synergistic adsorption effect on the surface, which can form a compact film to hinder the invasion of corrosive species. Overall, this study provides new insights for developing smart pH-responsive and superior anticorrosion coatings.

Research of Water Absorption and Release Mechanism of Superabsorbent Polymer in Cement Paste.

The water absorption and release properties of superabsorbent polymers' (SAP) internal curing agent are affected by many factors, such as solution properties, the ambient temperature and humidity and the particle size of SAP, which determine the curing effect and the durability of cement concrete structures directly. In this paper, the variation rule of the water absorbing capacity of SAP in simulated cement paste under different solutions and environmental conditions was studied. Based on microscopic image technology, the dynamic swelling behavior of the SAP particles was explored. The water release performance of SAP in cement paste was analyzed by both the tracer method and the negative pressure method. The results show that the water absorption of SAP in cement paste varied from 27 to 33 times. The ionic valence had a significant effect on the water absorption capacity of SAP, which suggests that the larger the ionic radius, the lower the absorption of SAP. The higher the temperature of the solution, the greater the water absorption rate of SAP. While the SAP particle size was less than 40-80 mesh, a slight 'agglomeration effect' was prone to occur, but the absorption state of SAP was more stable. Based on the swelling kinetic equation of SAP and the time-dependent swelling morphology of SAP in cement paste, a swelling kinetic model was established. The water release performance of SAP was less affected by the capillary negative pressures, and it would not release the water prematurely during the plastic stage, which was conducive to the continuous internal curing process of hardened paste in the later stage.

Respiratory protective device: One size to fit them all?

When exposed to hazardous or toxic substances, workers may be required to wear respiratory protective devices, selected in accordance with the pollutant, required protection level, individual characteristics, and work conditions. To emphasize the importance of the selection procedure, this study aimed to investigate the effects of the facial dimensions and breathing rate on the fit and the protection efficiency provided by full-face respirators. Manikin total efficiency measurements (mTEs) were then conducted on five head forms of various facial dimensions equipped with nine respirators of different models and sizes. A breathing machine simulating sinusoidal breathing rates was used to represent seven work rates, from rest to maximal intensity. For each experiment, the manikin fit factor (mFF), characterizing the respirator fit on the head form, was measured by a controlled negative pressure method. By varying the head form, respirator, breathing rate, and mFF, a total of 485 values of mTE were measured. Findings indicate that even if the respirator was equipped with a high-efficiency filter, mTE strongly decreases if the respirator does not fit the face of the wearer. In particular, it was highlighted that one given respirator cannot fit all facial dimensions and that the best match between the respirator size and facial dimensions is difficult to predict because respirator sizes are not standardized. Moreover, although the total efficiency of a well-fitted respirator naturally decreases when increasing the breathing rate due to filtration mechanisms, the reduction is more significant if the respirator does not fit well. To consider both the mTE and the breathing resistance, a quality factor value was determined for each tested combination of head form, respirator, and breathing rate. The maximum manikin fit factor mFFmax measured for each combination of head form and respirator was compared to that measured on nine human subjects with similar facial dimensions, providing encouraging results concerning the use of head forms during respirator testing.

Biological properties of hydroxyapatite coatings on titanium dioxide nanotube surfaces using negative pressure method.

Titanium (Ti) exhibits superior biocompatibility and mechanical properties but is bioinert, while hydroxyapatite (HA) possesses excellent osteogenesis and is widely used for the modification of Ti surface coatings. However, the synthesis of homogeneous and stable HA on metallic materials is still a major challenge. In this study, porous titanium dioxide nanotube arrays were prepared on Ti surface by anodic oxidation, loaded with calcium and phosphorus precursors by negative pressure immersion, and HA coating was formed by in situ crystallization of calcium and phosphorus on the surface by hydrothermal heating. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and bonding strength were conducted to confirm the surface characteristics of each group. The cell proliferation, mineralization degree, and alkaline phosphatase (ALP) activity of MC3T3-E1 cells on samples were calculated and compared in vitro experiments. Cylindrical samples were implanted into rat femurs to evaluate biocompatibility and osteogenesis in vivo. The results showed that HA crystals successfully synthesized in TiO2 nanotubes, enhancing the bonding strength of HA coating and Ti substrate under negative pressure. Moreover, HA coating on Ti substrate remarkably enhanced cell proliferation and osteogenic differentiation activity in vitro, and improved new bone formation as well as osseointegration in vivo.

Carbonized biomass cattail for flexible pressure sensor

The bio-based flexible sensing materials with flexibility, environmentally friendly, facile preparation and high sensitivity have a broad application prospect in pressure sensing applications. Herein, we reported a cellulose-based pressure sensors manufactured by a simple vacuum negative pressure method with carbonized cattail and polydimethylsiloxane (PDMS). The external strain and stress stimuli transformed into electrical signal successfully through the sensor. The PDMS/ carbonized cattail pressure sensor with a facile preparation process has an excellent mechanical property including high compressibility and durability simultaneously. Moreover, it exhibited a high sensitivity in the compressive range from 0% to 15%, and the corresponding electrical signals can be detected continuously. In addition, the PDMS/carbonized cattail pressure senor could measure the weight within a certain weight with an excellent linear relationship between weights and electrical signals. These characteristic make the senor a good candidate for human motion monitoring.

Biomimetic human eyes in adaptive lenses with conductive gels

To investigate the imaging effect, adaptive robust lenses are prepared by sealing transparent liquid or gel. Lenses are fabricated using the negative-pressure method, which is a benefit for a stable biconvex shape. Under the action of an electric field, the soft lens deforms following the dielectric elastomer actuator (DEA). DE (dielectric elastomer) membranes expand in the plane perpendicular to the electric field lines. The toroidal driving area leads to a decrease in lens diameter and an increase in convex curvature. Therefore, the focal length of the lens becomes shorter. The experimental measurement utilizes the double focal length method. As a result, the largest focal length change that could be achieved was 44.7% (190 mm→105 mm) of the soft lens using a DEA with carbon grease electrodes. Furthermore, the ECG (electrocardiogram) conductive gel could replace traditional carbon grease for DEA electrodes in optics. This type of transparent electrode is creatively applied to a biomedical lens. Under the same conditions, the electrostriction rate in a DEA with ECG gel was achieved at 33%, which was greater than that of 28% in a DEA coupled with carbon grease electrode. Adaptive lenses have characteristics such as easy fabrication, low cost, and strong operability, and they possess great potential application value in biomedical feild.

Improving the controlled-release effects of composite flame retardant by loading on porous attapulgite and coating

The attapulgite (ATP) is one of important raw materials of ceramics and often used as a loading carrier. To control the release rate of composite flame retardant (CFR) when exposed to a fire, and to meet the multi-stage flame retarding requirements, the vacuum negative pressure method was adopted to load four kinds of monomer flame retardants on porous ATP as a carrier after activating pretreatment, respectively. Then CFR nanoparticles with controlled-release effects were prepared by the in-situ polymerization reaction on the surface of monomer flame retardants. After that, zinc hydroxyl stannate, styrene, melamine formaldehyde resin and silicon dioxide with high thermal stability and excellent flame retarding properties were selected as the coating layer of four kinds of monomer flame retardants on ATP carrier. Test results of environmental scanning electron microscope and energy dispersive spectrometer show the satisfactory loading and coating results of CFR nanoparticles. Test results of X-ray photoelectron spectroscopy further confirm the excellent loading conditions and coating film formation on ATP carrier. The thermogravimetry-differential thermal scanning calorimetry tests indicate that the flame retarding duration of both loaded and coated CFR nanoparticles on ATP carrier is prolonged and has a satisfactory controlled-release effect.

Microbiological spectrum of causative agents of implant-associated infection in the treatment of complications of transpedicular fixation of the spine using the negative pressure method

Objective. To analyze the leading pathogens of implant-associated infection (IAI) after spinal surgery and identification of trends in the change in the pattern of microorganisms at the stages of treatment using the negative pressure method (NPWT systems).Material and Methods. The results of microbiological cultures of 25 patients with IAI of the spine were studied. The frequency of occurrence of Gram-positive and Gram-negative pathogens was estimated. The leading pathogens in the species spectrum were identified. Changes in the structure of identified microorganisms were studied at various time intervals of treatment.Results. A total of 136 microbiological studies were performed in 25 patients at the stages of treatment with the negative pressure method, with the identification of microorganisms in 127 (93.3 %) cases. The frequency of gram-negative microflora was 50.0 %, gram-positive – 42.6 %, Candida sp. – 0.7%, in 15.4 % microbial associations with the dominance of gram-negative microflora were identified at all periods of treatment. Not only the diversity of the isolated flora was noted (E. faecalis – 16.5 %, P. aeruginosa – 14.2 %, K. pneumoniae – 11.0 %, S. aureus and A. baumannii – 9.4 % each and S. epidermidis – 8.6 %), but also changes in the spectrum of flora at the stages of treatment: on the 1st and 2nd weeks from the first debridement intervention and the installation of the NPWT system, E. faecalis was most often detected, on the 3rd and 4th weeks – P. aeruginosa and A. baumannii, during the 2nd month – E. faecalis and P. aeruginosa, later – gram-negative bacteria against the background of an increase in the incidence of K. pneumoniae. The frequency of verification of other species of microorganisms had no statistically significant differences. Microbial associations were found from the 2nd month of treatment. The change in pathogens was noted in 72 % of cases during the treatment of IAI of the spine. On average, this treatment required 7–8 NPWT dressing changes per patient. This method of treatment made it possible to achieve both negative results of microbiological examination and stable relief of the infectious process.Conclusion. IAI, which complicates surgical interventions on the spine, is characterized by a change in pathogens during treatment, which requires not only multiple debridement with the replacement of the NPWT dressing, but also adequate long-term rational (etiologically justified) antibacterial therapy, based on the control of data on both the spectrum and on microbial resistance.

Removal of collagen three-dimensional scaffold bubbles utilizing a vacuum suction technique.

The process of generating type I/II collagen scaffolds is fraught with bubble formation, which can interfere with the three-dimensional structure of the scaffold. Herein, we applied low-temperature vacuum freeze-drying to remove mixed air bubbles under negative pressure. Type I and II rubber sponges were acid-solubilized via acid lysis and enzymolysis. Thereafter, vacuum negative pressure was applied to remove bubbles, and the cover glass press method was applied to shape the type I/II original scaffold. Vacuum negative pressure was applied for a second time to remove any residual bubbles. Subsequent application of carbamide/N-hydroxysuccinimide cross-linked the scaffold. The traditional method was used as the control group. The structure and number of residual bubbles and pore sizes of the two scaffolds were compared. Based on the relationship between the pressure and the number of residual bubbles, a curve was created, and the time of ice formation was calculated. The bubble content of the experimental group was significantly lower than that of the control group (P < 0.05). The pore diameter of the type I/II collagen scaffold was higher in the experimental group than in the control group. The time of icing effect of type I and II collagen solution was 136.54 ± 5.26 and 144.40 ± 6.45s, respectively. The experimental scaffold had a more regular structure with actively proliferating chondrocytes that possessed adherent pseudopodia. The findings indicated that the vacuum negative pressure method did not affect the physical or chemical properties of collagen, and these scaffolds exhibited good biocompatibility with chondrocytes.

Experimental Study on High-Temperature Damage Repair of Concrete by Soybean Urease Induced Carbonate Precipitation

In this study, the effects of soybean-urease-induced carbonate precipitation on a high-temperature damage repair of concrete were explored. C50 concrete specimens were exposed to high temperatures from 300 to 600 °C, then cooled to an ambient temperature and repaired by two different methods. The influences of the damage temperature and repair methods on surface film thickness, average infrared temperature increase, water absorption, and compressive strength were investigated. Scanning electron microscopy (SEM) images were carried out to further study the mechanism involved. The results revealed that the white sediments on the surface of the repaired specimens were calcium carbonate (CaCO3) and calcium oxalate (CaC2O4). The surface film thickness reached up to 1.94 mm after repair. The average infrared temperature increase in the repaired specimens at different damage temperatures was averagely reduced by about 80% compared with that before the repair. It showed more obvious repair effects at higher temperatures in water absorption and compressive strength tests; the compressive strength of repaired specimens was 194% higher than that before repairs at 600 °C. A negative pressure method was found to be more effective than an immersion method. This study revealed the utilization of SICP on repairing high-temperature damage of concrete is feasible theoretically.

Service life of sewage culvert with bacteria coating from waste sludge and negative pressure method

Service life of sewage culvert with bacteria coating from waste sludge and negative pressure method

Catalytic ozonation membrane reactor integrated with CuMn2O4/rGO for degradation emerging UV absorbers (BP-4) and fouling in-situ self-cleaning

• The combination of CuMn 2 O 4 and rGO enhanced the catalytic ozonation. • Coating times and calcination temperature determined catalytic membrane properties. • [Ozone] and TMP affected the degradation of micropollutants significantly. • Self-cleaning and catalytic ozonation are catalytic ceramic membrane superiority. To develop degradation efficiency of emerging ultraviolet absorbers (benzophenone-4, BP-4) and in-situ self-cleaning of membrane fouling in membrane filtration, a novel CuMn 2 O 4 /rGO catalytic ceramic membrane (CR/CM) was fabricated and used in catalytic ozonation membrane reactor (COMR) for water purification. Firstly, the CuMn 2 O 4 /rGO powder catalyst was optimized, according to the performance of catalytic ozonation BP-4. After that, the potential reaction sites was proposed as surface oxygen defect in CuMn 2 O 4 /rGO. Secondly, the optimized CuMn 2 O 4 /rGO powder was deposited on the surface of ceramic membrane by the vacuum negative pressure method. The thickness and roughness of the active layer were adjusted by changing the coating times. The best fabrication condition was twice surface coating. The performance of this CR/CM mainly depended on [ozone] and transmembrane pressure (TMP). The optimum reaction parameters were [ozone] = 20 mg/L and TMP was 0.20 bar. Compared with the pristine ceramic membrane coupled with ozonation, the degradation efficiency of BP-4 increased by 61.3%, the self-cleaning efficiency of catalytic membrane was 52.87%. The proposed COMR, gave a full play to the respective advantages of membrane filtration and catalytic ozonation technology, including degrading micro-organic pollutants effectively and alleviating membrane fouling.

A Method for Solving Percolation Overflow Boundary Based on Maximum of Horizontal Energy Loss Rate

The determination of overflow boundary is a prerequisite for the accurate solution of the seepage field by the finite element method. In this paper, a method for solving overflow boundary according to the maximum value of horizontal energy loss rate is proposed, which based on the analysis of the physical meaning of functional and the water head distribution of seepage field under different overflow boundaries. This method considers that the overflow boundary that makes the horizontal energy loss rate reach the maximum value is the real boundary overflow. Compared with the previous iterative computation method of overflow point and free surface, the method of solving overflow boundary based on the maximum horizontal energy loss rate does not need iteration, so the problem of non-convergence does not exist. The relative error of the overflow points is only 1.54% and 0.98% by calculating the two-dimensional model of the glycerol test and the three-dimensional model of the electric stimulation test, respectively. Compared with the overflow boundary calculated by the node virtual flow method, improved cut-off negative pressure method, initial flow method, and improved discarding element method, this method has a higher accuracy.

Enhancement of Strength and Resistance to Sulfate Attack in Bio-Coating Material through Negative Pressure Method for Bacteria Immobilization

In recent years, many studies have been performed on the crack repairing technique in concrete or the protection of the concrete surface against sulfate ions. Bacterial immobilization and survival rate are the dominant influencing factors for the repair of concrete. In this study, a negative pressure method (NPM) was developed to forcibly remove air in the porous materials of concrete, which was applied for surface repair through bio-coating using Rhodobacter capsualtus. For normal repair—repair using the conventional simple soaking method (SSM) and repair through NPM—various evaluations of the concrete strength and durability were performed. Since a reinforced concrete (RC) structure for the application of these repair methods is a sewer pipe exposed to sulfate ingress, variations in concrete mass and strength were analyzed by the accelerated sulfate resistance test. The diffusion coefficient of the sulfate ion in the repair materials and the bacterial count after the accelerating test were also measured. In order to investigate the changes in the properties of the concrete hydrates, surface analyses with SEM, XRD, and TGA were carried out on the concrete under the repair layer after the tests. In all the experimental results, the bacterial immobilization rate was evaluated, and the high immobilization rate indicates the excellent shielding of sulfate ions as well as improves the survival rate of bacteria. This not only improves the service life of the coating repair but also extends the service life of the structure itself. As a result of analyzing the composition of concrete protected by different types of repair, the results most similar to the general concrete composition without sulfate attack were obtained in the case of applying NPM, which shows the least damage from sulfate attack.

TREATMENT OF LONG-TERM NON-HEALING PURULENT WOUNDS OF THE LOWER LIMBS USING VAC-THERAPY

Summary. The purpose of the study is - To improve the results of treatment of patients with purulent long-term non-healing wounds of the lower extremities using the method of local negative pressure.in purulent long-term non-healing wounds (PLTNHW).&#x0D; Objectives of the research — according to the clinic’s data, to study the features of the course of the wound process and the microbiological characteristics of purulent long-term non-healing wounds of the lower extremities when exposed to the wound surface of local negative pressure.&#x0D; Conclusions. The use of the local negative pressure method in the complex treatment of patients with purulent long-term non-healing wounds of the lower extremities helps to reduce the duration of the phases of the course of the wound process, early tissue decontamination and a rapid reduction in the size of wound defects.

Dyspnea During Night-Time and at Early Morning in Patients with Stable COPD is Associated with Supine Tidal Expiratory Flow Limitation.

RationalePatients with chronic obstructive pulmonary disorder (COPD) complain of various COPD-related symptoms with different daily frequencies. During the night-time and at early morning, dyspnea is often reported and may predict an increased risk of COPD exacerbation and hospitalization and all-cause mortality. The aim of the study was to assess the underlying mechanisms of this symptom, seeking functional biomarkers of its occurrence.MethodsStable COPD patients with moderate-to-severe airflow obstruction and without confounding comorbidities underwent extensive baseline function respiratory tests. Spirometry, maximal flow-volume curves, lung volumes, and lung diffusion capacity parameters were obtained. Inspiratory capacity was also measured both in seated and supine positions. Forced oscillation technique (FOT) and negative expiratory pressure (NEP) method were used to establish the presence of tidal expiratory flow limitation (EFL) during recumbency. Questionnaires for recording COPD-related symptoms were administered. Sleep-related disturbances reported by the patients were also registered.ResultsForty-two consecutive COPD patients aged 65±9 completed the protocol. They were divided, according to the absence (NFL) or presence (FL) of supine EFL, in NFL group (n=17) and FL group (n=25). FL COPD patients had more severe airflow obstruction (FEV1= 46.4±19.4 vs 65.1±12.5% pred., p<0.01) and they showed no increase of supine IC in contrast with NFL COPD patients (ΔIC= 0.080±0.18 vs 0.390±0.28 L, p<0.01). Dyspnea either during night-time and at early morning was significantly more reported in FL COPD patients than in NFL COPD patients (p<0.05) and in those with less than 10% increase in supine IC (p<0.05).ConclusionSupine EFL is frequently associated with both night-time and early morning dyspnea, suggesting that the development of recumbent dynamic pulmonary hyperinflation, heralded by the lack of increment of IC in supine position, is a pivotal mechanism of this symptom. No or trivial increase in supine IC may indicate the occurrence of dyspnea under these conditions.

The Mobile Lower Body Negative Pressure Gravity Suit for Long-Duration Spaceflight.

Spaceflight Associated Neuro-ocular Syndrome, bone decalcification, and muscle atrophy are among the most prevalent risks associated with long-duration spaceflight. Implementing the lower body negative pressure (LBNP) method is a potential countermeasure for these risks. LBNP counteracts head-ward fluid shifts and generates ground-reaction forces (GRFs). GRFs are beneficial for maintaining bones and muscles by producing gravity-like loads experienced on Earth. Currently, LBNP devices are large/bulky, and usually require the subject to maintain a stationary position. However, our new mobile gravity suit is relatively small, untethered, and flexible in order to improve mobility in space. We hypothesized that this novel mobile gravity suit generates greater GRFs than a standard LBNP chamber. While lying supine, GRF data were recorded in both devices using foot sole sensors and a weight scale. At -40 mmHg, the gravity suit generated a mean maximum bodyweight of 125 ± 22% (P < 0.02) whereas the standard LBNP chamber generated 91 ± 24%. The standard LBNP chamber generated a single force on the stationary subject, which was expressed as AW(LBNP) = GRF, where Aw = cross-sectional area (CSA) of subject’s waist. However, the mobile gravity suit generated an additional force based on the following equation, (AF + AW)LBNP = GRF, where AF = CSA of subject’s feet. The additional force was further expressed as F1 + F2 = AF × LBNP, where F1 = spinal loading force, F2 = waist shear force, and AF × LBNP = the total downward foot force. Thus, the mobile gravity suit produces higher percentages of bodyweight due to the suit’s novel design.