Constant Low Pressure Research Articles

Theoretical and Molecular Dynamics Simulation Approaches to Praseodymium Content Effect on Radiation Shielding and Time Dependent Volume‐Collapse for a Newly Produced Borate Glass

AbstractGamma‐ray, fast neutron and charged particle shielding characteristics of Praseodymium (Pr3+) activated glasses with composition 10ZnF2‐(10‐x)SrO‐15Li2O‐65H3BO3‐xPr2O3(where x = 0.1, 0.5, 1.0, 1.5, and 2.0) are investigated. For this, the radiation shielding parameters are estimated by using Photon Shielding and Dosimetry (Phy‐X/PSD), Interaction of Proton, Alpha, Gamma rays, Electrons, and X‐rays with matter (PAGEX), Stopping Powers and Ranges for Electrons (ESTAR), and The Stopping and Range of Ions in Matter (SRIM) codes. Furthermore, the results are compared comprehensively and comparatively. The glasses with increasing Pr3+ content exhibited higher shielding potential. It can be said that the ZFLHBPr2.0 sample could be used as a shielding material in various applied fields. Additionally, the effect of Pr composition on structural transitions and time‐dependent volume‐collapse of this new family of borate glass doped with Pr is analyzed by molecular dynamics study (MD) based density functional tight binding method. The simulation results show that the addition of Pr led to the cubic‐orthorhombic transformation of simulation cell at determined temperature and 1 atm pressure. Also, a sudden decrease in volume are observed within a short time at 8% Pr composition (x = 2.0) atmospheric pressure. This result provides a strong connection between Pr composition and volume change with time and at constant low pressure.

A realist evaluation of devices used for the prevention of heel pressure ulcers: An ethnographic study of clinical practice

BackgroundIt is known that heel offloading devices are widely used in clinical practice for the prevention of heel pressure ulcers, even though there is a lack of robust, good quality evidence to inform their use. ObjectiveTo explore how and why heel offloading devices are used (or not used) and reasoning behind their use in population at high risk of developing heel pressure ulcers. MethodsAn ethnographic study was conducted as part of a realist evaluation in three orthopaedic wards in a large English hospital. Twelve observations took place, with 49 h and 35 min of patient care observed. A total of 32 patients were observed and 19 members of the nursing team were interviewed and in-depth interviews with the three ward managers were conducted. ResultsAlthough the focus of the study was on offloading devices, constant low pressure heel specific devices were also observed in use for pressure ulcer prevention, whilst offloading devices were perceived to be for higher risk patients or those already with a heel pressure ulcer. Nursing staff viewed leadership from the ward manager and the influence of the Tissue Viability Nurse Specialists as key mechanisms for the proactive use of devices. ConclusionsThis study informs trial design as it has identified that a controlled clinical trial of both types of heel specific devices is required to inform evidence-based practice. Involving the ward managers and Tissue Viability Nurse Specialists during set up phase for clinical equipoise could improve recruitment.Tweetable abstractHow, for whom, and in what circumstances do devices work to prevent heel pressure ulcers? Observations of clinical practice.

Effects of simulated climate change conditions of increased temperature and [CO2] on the early growth and physiology of the tropical tree crop, Theobroma cacao L.

Despite multiple studies of the impact of climate change on temperate tree species, experiments on tropical and economically important tree crops, such as cacao (Theobroma cacao L.), are still limited. Here, we investigated the combined effects of increased temperature and atmospheric carbon dioxide concentration ([CO2]) on the growth, photosynthesis and development of juvenile plants of two contrasting cacao genotypes: SCA 6 and PA 107. The factorial growth chamber experiment combined two [CO2] treatments (410 and 700p.p.m.) and three day/night temperature regimes (control: 31/22°C, control+2.5°C: 33.5/24.5°C and control+5.0°C: 36/27°C) at a constant vapour pressure deficit (VPD) of 0.9kPa. At elevated [CO2], the final dry weight and the total and individual leaf areas increased in both genotypes, while the duration for individual leaf expansion declined in PA 107. For both genotypes, elevated [CO2] also improved light-saturated net photosynthesis (Pn) and intrinsic water-use efficiency (iWUE), whereas leaf transpiration (E) and stomatal conductance (gs) decreased. Under a constant low VPD, increasing temperatures above 31/22 °C enhanced the rates of Pn, E and gs in both genotypes, suggesting that photosynthesis responds positively to higher temperatures than previously reported for cacao. However, dry weight and the total and individual leaf areas declined with increases in temperature, which was more evident in SCA 6 than PA 107, suggesting the latter genotype was more tolerant to elevated temperature. Our results suggest that the combined effect of elevated [CO2] and temperature is likely to improve the early growth of high temperature-tolerant genotypes, while elevated [CO2] appeared to ameliorate the negative effects of increased temperatures on growth parameters of more sensitive material. The evident genotypic variation observed in this study demonstrates the scope to select and breed cacao varieties capable of adapting to future climate change scenarios.

The biomechanical efficacy of a hybrid support surface in protecting supine patients from sacral pressure ulcers.

Support surfaces are the most important pressure ulcer/injury prevention technology available to clinicians for protecting their at-risk patients. A hybrid support surface marries the benefits of reactive and active support surfaces, by using high-quality foam material inside inflatable air cells. When used in its "static mode", it is a constant low air pressure mattress which delivers pressure redistribution in response to patient bodyweight and movements, by maximising the immersion and envelopment performance of the support surface. When used in its powered "dynamic mode", this system further delivers alternating pressure care via the connected foam and air cells. Modes of action of hybrid support surfaces were never studied quantitatively before, excluding through the limited scope of interface pressure mapping. In this work, we developed a novel computational modelling framework and simulations to visualise and quantify the state of soft tissue loading at the buttocks of a supine patient positioned on a hybrid support surface, in both the static and dynamic modes. We found that the dynamic mode effectively shifts deep concentrated soft tissue loading from under the sacral bone (towards the sacral promontory) to the tip of the sacrum (coccyx) and vice versa, and thereby, generates a deep tissue offloading effect.

Desenvolvimento da Órtese de Descompressão Occipital (ODO) para pacientes críticos em unidades de terapia intensiva

Abstract Introduction Pressure ulcers (PU) are caused by prolonged contact of the skin with a surface, leading to significant damage that is difficult to recover from. Occupational therapists can play a role in preventing these injuries through the creation of assistive technology devices. Objectives To present the development of a device to prevent and treat PU in the occipital region: the Occipital Decompression Orthosis (ODO). Method This is an exploratory study applied using the project management method and developed in four stages. The device began to be developed in 2017 in a reference trauma hospital in the metropolitan region of Belém, state of Pará, Brazil. Results A survey of devices available on the market was conducted, from which the ODO was developed. This orthosis uses the pyramidal mattress, a low-cost material that provides constant low pressure on the patient’s occipital segment and was designed through an anthropometric assessment. Based on a literature review and a financial study, a model was created for decompression of the segment. This alternative model is low-cost and effective in preventing PU. Conclusion The ODO is still under a refinement process. Although it is based on current literature addressing pressure injury prevention, it is still necessary to conduct a rigorous scientific study to verify its efficacy. The ODO presents limitations, especially regarding its approval for use by hospitals.

Comparative effectiveness of heel-specific medical devices for the prevention of heel pressure ulcers: A systematic review

BackgroundPressure ulcers (PUs) impact on patient's quality of life and are costly for healthcare providers. Heels are a particular concern due to specific risk factors. Relative effectiveness of medical devices, e.g., dressings, off-loading devices, heel cushioning devices, to reduce PU development is unknown. MethodsSystematic review of the effectiveness of heel-specific medical devices for the prevention of heel PU (HPU)s. Database searches were performed from inception to June 2021 for RCTs. The primary outcome was incidence of new HPUs. Trials were assessed for risk of bias and data analysed with risk ratios, mean difference or hazard ratios as appropriate. ResultsFifteen RCTs (4724 participants) were identified.Dressings, as constant low pressure (CLP) devices vs standard care: eight trials (very low quality) showed no-significant difference in effectiveness (RR 0.31, 95%CI 0.10 to 1.01).Off-loading devices vs standard care: three trials (low quality), showed significant reduction in development of Category≥1 HPUs (RR 0.20, 95%CI 0.05 to 0.80) two trials (medium quality), showed significant reduction in development of Category≥2 HPUs (RR 0.08, 95%CI 0.01 to 0.67).Comparisons between off-loading devices: two trials (low quality) showed no clear difference in HPU incidence.In a paediatric post-surgical population, one trial of off-loading device and one of a dressing (CLP device), both versus standard care, showed no clear difference in HPU incidence (RR 0.19 95%CI 0.02 to 1.55 and RR 0.89 95%CI 0.56 to 1.42 respectively). ConclusionsOff-loading devices may reduce HPU incidence, from low-quality evidence. There is insufficient evidence to suggest that dressings reduce HPU incidence.

Creep properties and constitutive model for salt rock subjected to uniaxial trapezoidal cyclic loading

Uniaxial trapezoidal cyclic loading creep tests with different loading and unloading rates are performed on salt rock to study its creep properties. The results indicate that the axial strain produced by salt rock under trapezoidal cyclic loading occurs mainly in the 1st cycle, and other cycles generate less axial strain. The existence of constant high pressure stage leads to an obvious horizontal segment in the stress-strain curve, while constant low pressure stage has little effect on its stress-strain curve. The stress-strain curve in the 1st cycle includes elastic stage, plastic stage, creep stage and deformation recovery stage. The axial strain generated at plastic deformation stage gradually tends to 0 with increasing cycle numbers, then the curve in a single cycle includes only elastic stage, creep stage and deformation recovery stage. When the cycle numbers is small, the irreversible deformation produced by salt rock in a single cycle mainly consists of plastic deformation produced at the loading stage and creep deformation generated at the constant high pressure stage. After several cycles, the irreversible deformation in a single cycle mainly consists of creep deformation generated at the constant high pressure stage. With increasing cycle numbers, the minimum value of creep rate in a single cycle basically does not change, and the maximum value of creep rate decreases firstly and then keeps constant. Moreover, with increasing loading rate, the mean value of minimum creep rate basically remains unchanged and the mean value of maximum creep rate gradually increases. With increasing unloading rate, both the mean values of minimum and maximum creep rate decrease gradually. Finally, the creep equation for the Burgers model subjected to trapezoidal cyclic loading is deduced, and the reasonableness of which is checked.

Do clinical practice guidelines for the prevention of pressure ulcers really prevent pressure ulcers? An analysis of the guidelines

This review article aims to analyze sections of the 2012 Australian Wound Management Association, Pan Pacific, Clinical Practice Guideline for the Prevention and Management of Pressure Injury, the “Guide,” mandated for use in all Australian residential aged care facilities to explain why pressure ulcers still occur, I considered two sections of the “Guide:” a) “Assess all patients as soon as possible following admission to service and within a minimum of 8 h;” and b) “Implement a prevention plan – strategies for patients at high risk: Use a high specification foam reactive (constant low pressure) support surface OR consider using an (active alternate pressure) support surface.” Nowhere in the “Guide” is there an explanation for a) “Assessing all patients as soon as possible following admission and within a minimum of 8 h.” Similarly, there is no explanation for why b) “a high specification foam reactive (constant low pressure) support surface” is recommended to prevent pressure ulcers. The evidence for screening “within a minimum of 8 h,” does not consider the speed at which pressure ulcers develop. If the resident is lying in one position for 30 min or more and a “constant low pressure” mattress is used, residents may still develop pressure ulcers because a “constant low pressure” does not relieve pressure.

Numerical Investigation on Shape Optimization of Small-Spacing Twin-Well for Salt Cavern Gas Storage in Ultra-Deep Formation

Small-spacing twin-well (SSTW) salt caverns have an extensive application prospect in thin or bedded rock salt formations due to their good performance, while they are rarely used in ultra-deep formations. The target strata depth of Pingdingshan salt mine is over 1700 m, and it is planned to apply an SSTW cavern to construct the underground gas storage (UGS). A 3D geomechanical model considering the viscoelastic plasticity of the rock mass is introduced into Flac3D to numerically study the influence of internal gas pressure, cavern upper shape and well spacing on the stability of an SSTW salt cavern for Pingdingshan UGS. A set of assessment indices is summarized for the stability of gas storage. The results show that the minimum internal gas pressure is no less than 14 MPa, and the cavern should not be operated under constant low gas pressure for a long time. The cavern with an upper height of 70 m is recommended for Pingdingshan gas storage based on the safety evaluation and maximum volume. The well spacing has a limited influence on the stability of the salt cavern in view of the volume shrinkage and safety factor. Among the values of 10 m, 20 m and 30 m, the well spacing of 20 m is recommended for Pingdingshan gas storage. In addition, when the cavern groups are constructed, the pillar width on the short axis should be larger than that on the long axis due to its greater deformation in this direction. This study provides a design reference for the construction of salt cavern gas storage in ultra-deep formations with the technology of SSTW.

РАЗРАБОТКА МОДЕЛИ ПТИЦЫ-УДАРНИКА ДЛЯ МАТЕМАТИЧЕСКОГО МОДЕЛИРОВАНИЯ ПРОЦЕССОВ ПОВРЕЖДЕНИЯ ДЕТАЛЕЙ ТУРБОРЕАКТИВНОГО ДВУХКОНТУРНОГО ДВИГАТЕЛЯ

This study aims to develop of the bird-impactor model for mathematical modeling of turbofan engine parts damage processes in case of a bird ingestion into the its air-gas channel. The bird-impactor model was justified for simulation of bird with mass of 0,70…3,65 kg for certification requirements on aircraft engines according to aviation regulations CS-E, FAR-33, AP-33. It was implemented in numerical SPH model for explicit LS-DYNA Solver of ANSYS LS-DYNA software package. The pre - and postprocessor LS-PrePost program also was used for numerical SPH model generating, preparing input data and processing the results from calculations. The bird-impactor model was had a hemispherical-ended cylinder geometry form. Material of the bird-impactor model was defined as a mixture of water (90-percent of volume) and air (10-percent of volume). The Null material model with low strength and the linear polynomial equation of state were used for the bird modeling. It was considered impacts bird to the rigid plate at striking velocities of 100...300 m/s and impact angle of 45°, 90° for the bird- impactor model verification. The rigid plate was modeled as a fixed thick steel plate. Volume of rigid plate was meshed with finite elements. The transducer was installed in center of the rigid plate. It was modeled by one finite element. The pressure of impact bird was obtained by dividing the contact force for finite element - transducer to its area. Thus the pressure curves were calculated for each impact bird to rigid plate. The Hugoniot pressure (shock pressure) was defined as maximum of pressure curve. The stagnation pressure was defined for phase of curve with approximately constant low pressure level by Simpson's rule. Verification of the developed bird-impactor model was performed by comparing the calculating results of Hugoniot and stagnation pressures used the developed bird-impactor, the one-dimensional hydrodynamic theory and calculation results of other authors. Verification of developed the bird-impactor model was shown good agreement with the one-dimensional hydrodynamic theory and with results of other authors.

Phospholipid fatty acids are correlated with critical thermal tolerance but not with critical pressure tolerance in the shallow-water shrimp Palaemon varians during sustained exposure to low temperature

Some extant deep-sea shrimp are known to be descended from shallow-water ancestors that adapted to environmental conditions (constant low temperature and high hydrostatic pressure) in the deep sea. During acclimation to low temperature and high hydrostatic pressure representative of the deep-sea, critical thermal tolerance decreases and critical pressure tolerance increases in the shallow-water shrimp Palaemon varians. It has been suggested that these shifts may depend in part on adjustments to phospholipid fatty acid composition and/or metabolic adjustments. Here, we present evidence that metabolic rate does not change during sustained exposure to low temperature (5 °C) in the shallow-water shrimp Palaemon varians, and that metabolic rate and acute environmental tolerances are not correlated during sustained exposure to low temperature, suggesting that standard metabolic rate does not affect acute environmental tolerances. In contrast, we present evidence that phospholipid fatty acid composition does shift during sustained exposure to low temperature. Desaturation of fatty acids during sustained exposure to low temperature supports the suggestion that cell lipid bilayer homeoviscous modifications are important in low temperature acclimation. Shifts in several individual phospholipid fatty acids during sustained low temperature exposure are correlated with critical thermal tolerance. Exploring the greater complexity apparent in the responses of these phospholipid fatty acids to sustained low temperature exposures suggests a potential homeostatic impact moderating adverse impacts on nervous system function. However, shifts in phospholipid fatty acids are not correlated with critical pressure tolerance during exposure to low temperature, suggesting that shifts in critical pressure tolerance are related to modifications other than cell lipid bilayer composition.

Hyperoxia affects the lung tissue: A porcine histopathological and metabolite study using five hours of apneic oxygenation

BackgroundOxygen is a liberally dosed medicine; however, too much oxygen can be harmful. In certain situations, treatment with high oxygen concentration is necessary, e.g. after cardiopulmonary resuscitation. The amount of oxygen and duration of hyperoxia causing pulmonary damage is not fully elucidated. The aim of this study was to investigate pathophysiological and metabolite changes in lung tissue during hyperoxia while the lungs were kept open under constant low pressure. MethodsSeven pigs were exposed to 100% oxygen for five hours, using an apneic oxygenation technique with one long uninterrupted inspiration, while carbon dioxide was removed with an interventional lung assist. Arterial blood samples were collected every 30 minutes. Lung biopsies were obtained before and after hyperoxia. Microscopy and high-resolution magic angle spinning nuclear magnetic resonance spectroscopy were used to detect possible pathological and metabolite changes, respectively. Unsupervised multivariate analysis of variance and paired sample tests were performed. A two-tailed p-value ≤ 0.05 was considered significant. ResultsNo significant changes in arterial pH, and partial pressure of carbon dioxide, and no clear histopathological changes were observed after hyperoxia. While blood glucose and lactate levels changed to a minor degree, their levels dropped significantly in the lung after hyperoxia (p ≤ 0.04). Reduced levels of antioxidants (p ≤ 0.05), tricarboxylic acid cycle and energy (p ≤ 0.04) metabolites and increased levels of several amino acids (p ≤ 0.05) were also detected. ConclusionDespite no histological changes, tissue metabolites were altered, indicating that exposure to hyperoxia affects lung tissue matrix on a molecular basis.

Parametric study of electronics components joining using reactive films for high temperature applications

Abstract In this paper, in order to assemble electronic components onto substrates, a local rapid soldering process using an exothermic reactive foil sandwiched between solder preforms was evaluated. Among others, the main interest of this technique is that it can allow the use of high temperature melting solders, without the need to heat the whole assembly above this melting temperature. The reactive foil is commercially available and is formed from alternatively stacked nanolayers of Ni and Al until it reaches the total film thickness. Once the film is activated by using an external power source, a reaction takes place and releases such an amount of energy that is transferred to the solder preforms. If this amount of energy is high enough, solder preforms melt and insure the adhesion between the materials of the assembly. The process was evaluated using a standard SAC305 and a high temperature Au80Sn20 preforms. The influences of the applied pressure, the reactive film thickness as well as the solder and the attached materials nature and thicknesses were investigated. The initial joint quality was evaluated using scanning acoustic microscopy, scanning electron microscopy, and shear strength measurements. It was shown that the applied pressure during the process has a strong effect on the joint initial quality. The voids ratio between metallized diode dice and an Active Metal Braze (AMB) substrate decreases from 64% to 26% for pressure values between 0.5kPa and 100kPa respectively. Otherwise, under a constant low pressure of 13kPa, reducing the substrate metal thickness on a low thermal conductivity insulator allows the improvement of the initial joint quality and a voids ratio of about 15% was reached when using 35μm of copper on FR4 substrate. The use of aluminum instead of copper as a metal for the ceramic metallized substrate (with the same gold finishing layer) led to a reduction in the void ratio in the joint. The microstructure of the AuSn joint achieved using the reactive films shows very fine phase distribution compared to the one obtained using conventional solder reflow process in the oven. The mechanical properties of the joint were evaluated using shear tests performed on 350μm thick silicon diodes assembled on AMB substrates under a pressure of 100kPa. The reactive films were 60μm thick and were sandwiched between two 25μm thick SAC preforms. The void ratio was about 37% for the tested samples and shear strength values above 9.5MPa were achieved which remains largely higher than MIL-STD-883H requirements. Finally, the process impact on the electrical properties of the assembled diodes was compared with a commonly used solder reflow assembly and results show a negligible variation.

Effect of nanobubbles on adsorption of sodium oleate on calcite surface

The aim of the study is to explore the effect of nanobubbles on the adsorption capacity of surfactants on mineral surfaces. Firstly, nanobubbles were imaged under the condition that the solution had a dissolved oxygen difference (DOD) by atomic force microscope (AFM). Subsequently, the calcite particles with 37–74 μm and sodium oleate (NaOL) were mixed and stirred under different mixing times and different pressure control (nanobubbles can be produced under the condition of decompression) through a self-made pressurization and decompression device. After nature sedimentation, the supernatant was extracted, and the change of the adsorption capacity of NaOL on the surface of calcite was detected by high performance liquid chromatography (HPLC). Finally, in order to study the direct influence of nanobubbles on the adsorption of NaOL on the surface of calcite, the NaOL on the surface of calcite were imaged under different pressure conditions by AFM. The experimental results showed that many nanobubbles were found on the calcite surface by AFM under the dissolved oxygen difference (DOD) condition of −4 mg/L. Furthermore, the order of adsorption of sodium oleate on the surface of calcite under different pressure conditions was as follows: constant low pressure (0.3 atm) > inflating (0.3 atm to 1 atm) > constant normal pressure (1 atm) > pumping gas (1 atm to 0.3 atm). More interestingly, compared with the constant pressure condition, the coverage of NaOL on the calcite surface was reduced under decompression pressure, about 30% lower at natural pH and about 20% lower at pH = 10, and this decrease was obvious. However, the change in adsorption height was considered by the author to be difficult to judge by AFM.The study concludes that nanobubbles can be generated under the condition that the DOD is less than 0. Moreover, nanobubbles not only promote the formation of floc, but also directly inhibit the adsorption of NaOL on the calcite surface, both reasons can inhibit the adsorption capacity of NaOL on the calcite surface.It provides a better idea and method for understanding of nanobubble, flotation, dissolved air flotation (DAF), and the interaction between surfactant and particles or particles and particles. These findings are benefit for these fields, such as mineral processing, biomedicine, etc.

Flow hydrogen absorption of LaFe10.9Co0.8Si1.3 compound under constant low hydrogen gas pressure

The hydrogen absorption of the LaFe10.9Co0.8Si1.3 compound under constant 1.01 × 105 Pa H2 gas in a flow hydrogen atmosphere was studied. The effects of hydrogen absorption on structure, Curie temperature, phase transition and magnetic property were investigated by X-ray diffraction (XRD), differential scanning calorimeter (DSC) and superconducting quantum interference device, respectively. The hydrides of LaFe10.9Co0.8Si1.3 crystallize into NaZn13-type structural phase after hydrogen absorption at temperature from 548 to 623 K. Lower hydrogen absorption temperature is of no advantage for pure 1:13 phase formation in a flow H2 atmosphere. The Curie temperature (TC) of LaFe10.9Co0.8Si1.3 compound increases by 70 K or more after hydrogen absorption. For LaFe10.9Co0.8Si1.3H1.8 compound, the maximum magnetic entropy change and the relative cooling power under a magnetic field change of 0–2 T are 6.1 J·kg−1·K−1 and 170 J·kg−1, respectively. Large refrigerant capacity, low hysteresis loss and wide temperature span of magnetic entropy change peak make it a competitive practical candidate for magnetic refrigerant.

Responses of ‘Rocha’ pear to delayed controlled atmosphere storage depend on oxygen partial pressure

Internal disorders hinder long-term controlled atmosphere (CA) storage of ‘Rocha’ pear. The delayed establishment of CA regime is often recommended to reduce internal disorders in pear. This investigation evaluated the effect of delayed CA at two oxygen partial pressures (pO2) at constant low CO2 partial pressure (pCO2) on internal disorders and on storage potential of ‘Rocha’ pear. Fruit were stored at −0.5°C for 257 d under 0.6kPa CO2 combined with 0.5 or 3.0kPa O2. The pull down of pO2 was imposed at the beginning of cold storage (immediate CA) or after 46 d (delayed CA). ‘Rocha’ pear tolerated immediate storage at 0.5kPa O2 without developing internal disorders for 257 d storage. However, 63.3% of fruit immediately stored at 3.0kPa O2 developed internal disorders. Delayed pull down of pO2 for 46 d reduced internal disorders in fruit at 3.0kPa O2 to 35.5%, but increased the disorder incidence in fruit at 0.5kPa O2 to 27.3%. Poststorage ethylene production rate was lower in fruit stored under delayed CA at 3.0 and 0.5kPa O2. In conclusion, the immediate storage of ‘Rocha’ pear at 0.5kPa O2 prevented the development of internal disorders for 257 d, while allowing adequate poststorage ripening and maintenance of quality traits. The effect of delayed CA on internal disorders depended on pO2. Delaying CA for 46 d did not benefit ‘Rocha’ pear during long-term storage.

A new experimental-numerical approach for studying the effects of gas pressure profile on superplastic forming characteristics of Al-Mg5.6 alloy

Controlling the strain rate during superplastic forming is the main reason to implement time-variable gas pressure profiles. In the present research, a new approach is introduced for controlling the strain rate during free bulge forming. The approach was examined by performing the superplastic forming operation with the Al-Mg5.6 aluminum alloy as a valuable material in transportation industries. Free bulge forming operations were performed at 500 °C and a strain rate range of 8 × 10−5–5.7 × 10−4 s−1. The changes of the strain rate at the apex of the workpiece were numerically monitored during the deformation, and a new strategy to smooth these changes was implemented. New time-dependent pressure profiles were defined, and their influences on the forming time and uniformity of the deformed part were examined. Finally, the stepwise rising pressure function followed by a constant pressure at which the time of increasing (Tr) was between 20 and 40% of the total time needed for merely applying that constant pressure was shown to provide the best results. This type of pressure profile can also improve the uniformity of thickness and save the process time, compared with forming at a constant low pressure. Moreover, this stepwise pressure function is easy to be practically employed in various industrial applications.

Non-pharmacological interventions to prevent or treat pressure ulcers in older patients: Clinical practice recommendations. The SENATOR-ONTOP series

IntroductionThe objective is to develop explicit and transparent recommendations for non-pharmacological interventions for older subjects at risk of developing pressure ulcers, as well as for older subjects with pressure ulcers, based on the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) approach to rating the quality of evidence and the strength of recommendations. Material and methodsA multidisciplinary panel was constituted. The results of the evidence retrieved were published in a systematic overview. The GRADE approach was used to rate the evidence and to formulate recommendations in older subjects in hospitals or nursing homes. ResultsThe critical outcomes were incidence of new pressure ulcers and rate of healing. Non-pharmacological interventions were identified. Strong recommendations in favour of the use of alternating pressure and constant low pressure devices in hospitalised (medical or surgical) and nursing home patients at high risk of developing pressure ulcers for ulcer prevention were formulated. In addition, strong recommendations were formulated in favour of regular repositioning to prevent pressure ulcers in older hospitalised patients. Weak recommendations support the use of nutritional intervention to prevent pressure ulcers and of either clinical judgment or assessment scales to detect individuals at risk. For healing of pressure ulcers, weak recommendations support the use of electrotherapy but not of mixed nutritional supplements. Preventive interventions have to be considered also in patients with pre-existing ulcers to reduce the risk of new pressure ulcers. ConclusionsOverall, the panel developed 9 recommendations for the delivery of non-pharmacological interventions to older patients with, or at risk of developing, pressure ulcers.

Support surfaces for pressure ulcer prevention.

Pressure ulcers (i.e. bedsores, pressure sores, pressure injuries, decubitus ulcers) are areas of localised damage to the skin and underlying tissue.They are common in the elderly and immobile, and costly in financial and human terms. Pressure-relieving support surfaces (i.e. beds, mattresses, seat cushions etc) are used to help prevent ulcer development. This systematic review seeks to establish:(1) the extent to which pressure-relieving support surfaces reduce the incidence of pressure ulcers compared with standard support surfaces, and,(2) their comparative effectiveness in ulcer prevention. In April 2015, for this fourth update we searched The Cochrane Wounds Group Specialised Register (searched 15 April 2015) which includes the results of regular searches of MEDLINE, EMBASE and CINAHL and The Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2015, Issue 3). Randomised controlled trials (RCTs) and quasi-randomised trials, published or unpublished, that assessed the effects of any support surface for prevention of pressure ulcers, in any patient group or setting which measured pressure ulcer incidence. Trials reporting only proxy outcomes (e.g. interface pressure) were excluded. Two review authors independently selected trials. Data were extracted by one review author and checked by another.Where appropriate, estimates from similar trials were pooled for meta-analysis. For this fourth update six new trials were included, bringing the total of included trials to 59.Foam alternatives to standard hospital foam mattresses reduce the incidence of pressure ulcers in people at risk (RR 0.40 95% CI 0.21 to 0.74).The relative merits of alternating- and constant low-pressure devices are unclear. One high-quality trial suggested that alternating-pressure mattresses may be more cost effective than alternating-pressure overlays in a UK context.Pressure-relieving overlays on the operating table reduce postoperative pressure ulcer incidence, although two trials indicated that foam overlays caused adverse skin changes. Meta-analysis of three trials suggest that Australian standard medical sheepskins prevent pressure ulcers (RR 0.56 95% CI 0.32 to 0.97). People at high risk of developing pressure ulcers should use higher-specification foam mattresses rather than standard hospital foam mattresses. The relative merits of higher-specification constant low-pressure and alternating-pressure support surfaces for preventing pressure ulcers are unclear, but alternating-pressure mattresses may be more cost effective than alternating-pressure overlays in a UK context. Medical grade sheepskins are associated with a decrease in pressure ulcer development. Organisations might consider the use of some forms of pressure relief for high risk patients in the operating theatre.

Adventitial vessel growth and progenitor cells activation in an ex vivo culture system mimicking human saphenous vein wall strain after coronary artery bypass grafting.

Saphenous vein graft disease is a timely problem in coronary artery bypass grafting. Indeed, after exposure of the vein to arterial blood flow, a progressive modification in the wall begins, due to proliferation of smooth muscle cells in the intima. As a consequence, the graft progressively occludes and this leads to recurrent ischemia. In the present study we employed a novel ex vivo culture system to assess the biological effects of arterial-like pressure on the human saphenous vein structure and physiology, and to compare the results to those achieved in the presence of a constant low pressure and flow mimicking the physiologic vein perfusion. While under both conditions we found an activation of Matrix Metallo-Proteases 2/9 and of microRNAs-21/146a/221, a specific effect of the arterial-like pressure was observed. This consisted in a marked geometrical remodeling, in the suppression of Tissue Inhibitor of Metallo-Protease-1, in the enhanced expression of TGF-β1 and BMP-2 mRNAs and, finally, in the upregulation of microRNAs-138/200b/200c. In addition, the veins exposed to arterial-like pressure showed an increase in the density of the adventitial vasa vasorum and of cells co-expressing NG2, CD44 and SM22α markers in the adventitia. Cells with nuclear expression of Sox-10, a transcription factor characterizing multipotent vascular stem cells, were finally found in adventitial vessels. Our findings suggest, for the first time, a role of arterial-like wall strain in the activation of pro-pathologic pathways resulting in adventitial vessels growth, activation of vasa vasorum cells, and upregulation of specific gene products associated to vascular remodeling and inflammation.