Types Of PVA Research Articles

Patient-ventilator asynchrony classification in mechanically ventilated patients: Model-based or machine learning method?

Background and objectivePatient-ventilator asynchrony (PVA) is associated with poor clinical outcomes and remains under-monitored. Automated PVA detection would enable complete monitoring standard observational methods do not allow. While model-based and machine learning PVA approaches exist, they have variable performance and can miss specific PVA events. This study compares a model and rule-based algorithm with a machine learning PVA method by retrospectively validating both methods using an independent patient cohort. MethodsHysteresis loop analysis (HLA) which is a rule-based method (RBM) and a tri-input convolutional neural network (TCNN) machine learning model are used to classify 7 different types of PVA, including: 1) flow asynchrony; 2) reverse triggering; 3) premature cycling; 4) double triggering; 5) delayed cycling; 6) ineffective efforts; and 7) auto triggering. Class activation mapping (CAM) heatmaps visualise sections of respiratory waveforms the TCNN model uses for decision making, improving result interpretability. Both PVA classification methods were used to classify incidence in an independent retrospective clinical cohort of 11 mechanically ventilated patients for validation and performance comparison. ResultsSelf-validation with the training dataset shows overall better HLA performance (accuracy, sensitivity, specificity: 97.5 %, 96.6 %, 98.1 %) compared to the TCNN model (accuracy, sensitivity, specificity: 89.5 %, 98.3 %, 83.9 %). In this study, the TCNN model demonstrates higher sensitivity in detecting PVA, but HLA was better at identifying non-PVA breathing cycles due to its rule-based nature. While the overall AI identified by both classification methods are very similar, the intra-patient distribution of each PVA type varies between HLA and TCNN. ConclusionThe collective findings underscore the efficacy of both HLA and TCNN in PVA detection, indicating the potential for real-time continuous monitoring of PVA. While ML methods such as TCNN demonstrate good PVA identification performance, it is essential to ensure optimal model architecture and diversity in training data before widespread uptake as standard care. Moving forward, further validation and adoption of RBM methods, such as HLA, offers an effective approach to PVA detection while providing clear distinction into the underlying patterns of PVA, better aligning with clinical needs for transparency, explicability, adaptability and reliability of these emerging tools for clinical care.

Effect of sodium 2‐acrylamido‐2‐methylpropanesulfonate on the structure and properties of thermoplastic polyvinyl alcohol copolymers

AbstractThermoplastic poly(vinyl alcohol) (PVA) with water‐soluble behavior has received great attention. In this work, a thermoplastic PVA was prepared via solution radical polymerization of vinyl acetate, vinyl pivalate and sodium 2‐acrylamido‐2‐methyl propane sulfonate (SAMPS). The effects of SAMPS content on the structure and properties of modified poly(vinyl alcohol) (MPVA) were investigated. On increasing the proportion of SAMPS, the characteristic band of –OH moved to a larger wavenumber. Compared to PVA, the melting temperature (Tm) of MPVA decreased from 223.1 to 161.5 °C at 0.03 mol of SAMPS, and the initial thermal decomposition temperature (Td) of MPVA increased from 244.3 to 262.2 °C at 0.05 mol of SAMPS. The crystallinity of the resin reduced from 51.46% to 10.21%. The enlarged difference between Td and Tm ensured the preparation of MPVA by thermal processing. The maximum tensile strength and elastic modulus of the obtained sheets were 137.56 and 2639.32 MPa, respectively. The introduction of SAMPS reduced the alcoholysis degree from 99.03% to 95.80%. The high alcoholysis degree of MPVA meant that it could be dissolved in water at 60 °C. This type of thermoplastic PVA shows a promising application on film and textiles that require water solubility. © 2024 Society of Chemical Industry.

The Mechanical Performance and Reaction Mechanism of Slag-Based Organic-Inorganic Composite Geopolymers.

A series of organic-inorganic composite geopolymer paste samples were prepared with slag-based geopolymer and three types of hydrophilic organic polymers, i.e., PVA, PAA, and CPAM, by ordinary molding and pressure-mixing processes. The reaction mechanism between slag-based geopolymer and organic polymers was studied by FT-IR, NMR, and SEM techniques. The experimental results showed that the slag-based geopolymer with the addition of 3% PVA presented the highest 28-day flexural strength of 19.0 MPa by means of a pressure-mixing process and drying curing conditions (80 °C, 24 h) compared with the geopolymers incorporating PAA and CPAM. A more homogeneous dispersion morphology was also observed by BSE and SEM for the 3% PVA-incorporated slag-based geopolymer. The FT-IR testing results confirmed the formation of a C-O-Si (Al) bond between PVA and the slag-based geopolymer. The deconvolution of the Q3 and Q2(1Al) species obtained by 29Si NMR testing manifested the addition of PVA and increased the length of the silicon backbone chain in the geopolymer. These findings confirmed that a composite geopolymer with high toughness can be produced based on the interpenetrating network structure formed between organic polymers and inorganic geopolymer.

Hyaluronic acid – PVA films for the simultaneous delivery of dexamethasone and levofloxacin to ocular tissues

Ocular drug delivery is challenging due to the poor drug penetration across ocular barriers and short retention time of the formulation at the application site. Films, applied as inserts or implants, can be used to increase residence time while controlling drug release. In this work, hydrophilic films made of hyaluronic acid and two kinds of PVA were loaded with dexamethasone (included as hydroxypropylcyclodextrin complex) and levofloxacin. This association represents one of the main treatments for the post cataract surgery management, and it is also promising for eye infections with pain and inflammation. Films were characterized in terms of swelling and drug release and were then applied to porcine eye bulbs and isolated ocular tissues. Film swelling leads to the formation of either a gel (3D swelling) or a larger film (2D swelling) depending on the type of PVA used. Films, prepared in an easy and scalable method, demonstrated high loading capacity, controlled drug release and the capability to deliver dexamethasone and levofloxacin to the cornea and across the sclera, to potentially target also the posterior eye segment. Overall, this device can be considered a multipurpose delivery platform intended for the concomitant release of lipophilic and hydrophilic drugs.

Basic Study on Manufacturing of Inkjet Paper by High-Speed Coating (II) : Effects of Binder Composition on Rheological Property of Inkjet Coating Colors

To investigate the change in coating-color characteristics upon blending water-soluble polymer [PVA(OH)] and emulsion binder (VAE), a VAE emulsion binder and two types of PVA(OH) with different molecular weights were used to design the blending composition. Then, the characteristics of the resulting coating colors were analyzed. In the case of the coating color using PVA, the smaller the molecular weight, the higher the elasticity. In both types of PVA having different polymerization degrees, the viscoelastic properties tended to increase as the blending ratio of the VAE emulsion increased. The high shear viscosity of the coating color decreased with an increase in the blending ratio of the VAE emulsion. The coating color using low-molecular-weight PVA exhibited low viscosity. The VAE emulsion binder has a lower high shear viscosity compared with PVA(OH) with a linear structure; hence, it has excellent runnability in terms of preparing coating colors.

Environmentally Friendly Melt-Processed Chitosan/Starch Composites Modified with PVA and Lignin.

Chitosan/starch-based composites were prepared by thermomechanical processing as an alternative to the traditional solution method, with the aim of fabricating environmentally friendly materials on a larger scale. Different contents and types of lignin and poly(vinyl alcohol), PVA were incorporated into chitosan/starch compositions to improve their mechanical properties. It was demonstrated that the presence of both lignin and PVA increases the values of tensile strength and elongation at break of the composites. Moreover, it was observed that by the selection of a type of lignin and PVA, it was possible to tailor the internal microstructure of the samples. As observed in scanning electron microscope (SEM) micrographs, the introduction of lignin and PVA resulted in the formation of a smooth surface and homogeneous samples.

An interpretable 1D convolutional neural network for detecting patient-ventilator asynchrony in mechanical ventilation

Background and ObjectivePatient-ventilator asynchrony (PVA) is the result of a mismatch between the need of patients and the assistance provided by the ventilator during mechanical ventilation. Because the poor interaction between the patient and the ventilator is associated with inferior clinical outcomes, effort should be made to identify and correct their occurrence. Deep learning has shown promising ability in PVA detection; however, lack of network interpretability hampers its application in clinic. MethodsWe proposed an interpretable one-dimensional convolutional neural network (1DCNN) to detect four most manifestation types of PVA (double triggering, ineffective efforts during expiration, premature cycling and delayed cycling) under pressure control ventilation mode and pressure support ventilation mode. A global average pooling (GAP) layer was incorporated with the 1DCNN model to highlight the sections of the respiratory waveform the model focused on when making a classification. Dilation convolution and batch normalization were introduced to the 1DCNN model for compensating the reduction of performance caused by the GAP layer. ResultsThe proposed interpretable 1DCNN exhibited comparable performance with the state-of-the-art deep learning model in PVA detection. The F1 scores for the detection of four types of PVA under pressure control ventilation and pressure support ventilation modes were greater than 0.96. The critical sections of the waveform used to detect PVA were highlighted, and found to be well consistent with the understanding of the respective type of PVA by experts. ConclusionsThe findings suggest that the proposed 1DCNN can help detect PVA, and enhance the interpretability of the classification process to help clinicians better understand the results obtained from deep learning technology.

Influences of PVA modification on performance of microencapsulated reversible thermochromic phase change materials for energy storage application

The aim of the paper was to enhance the mechanical properties and anti-permeability performance of microcapsules through shell modification to keep complete and stable structure during the manufacturing process. The effect of PVA adding dosage, modified methods and types of PVA on the performance of microcapsules was discussed in detail. When the PVA/MF ratio (0.04–0.25) was appropriate, the supercooling degree of microcapsules was reduced and thermal stability was improved to some extent. Furthermore, the modified method of adding PVA-1788 into microcapsules after curing probably formed the second protective encapsulation for RTPCMs, which contributed to obtaining MicroRTPCMs-2 with excellent mechanical properties and anti-permeability performance. Compared among the effects of various types of PVA modification on the performance of MicroRTPCMs, PVA with larger polymerization degree and higher alcoholysis degree can form modified resin with larger crosslinking degree, which was beneficial to generating more stable composite shell structure. Therefore, MicroRTPCMs1-2699 presented more outstanding mechanical properties and anti-permeability performance, satisfactory cycle stability and long-term reliability, as well as reversible thermochromic coloration and leakage-prevention performance. In the end, the main characteristic of RTPCMs was to in-situ observe the heat absorption, energy storage and heat release process of PCM cores, which would be great significance for the practical application of MicroRTPCMs in the fields of thermoregulated fibers, thermal energy storage textiles, heat energy transfers and energy-saving building materials.

Pulverization and Densification Behavior of YAG Powder Synthesized by PVA Polymer Solution Method

YAG (Yttrium Aluminum Garnet, Y3Al5O12) has excellent plasma resistance and recently has been used as an alternative to Y2O3 as a chamber coating material in the semiconductor process. However, due to the presence of an impurity phase and difficulties in synthesis and densification, many studies on YAG are being conducted. In this study, YAG powder is synthesized by an organic-inorganic complex solution synthesis method using PVA polymer. The PVA solution is added to the sol in which the metal nitrate salts are dissolved, and the precursor is calcined into a porous and soft YAG powder. By controlling the molecular weight and the amount of PVA polymer, the effect on the particle size and particle shape of the synthesized YAG powder is evaluated. The sintering behavior of the YAG powder compact according to PVA type and grinding time is studied through an examination of its microstructure. Single phase YAG is synthesized at relatively low temperature of 1,000 oC and can be pulverized to sub-micron size by ball milling. In addition, sintered YAG with a relative density of about 98 % is obtained by sintering at 1,650 oC.

Patient-Ventilator Asynchrony in Critical Care Settings: National Outcomes of Ventilator Waveform Analysis

BackgroundPatient–ventilator asynchrony (PVA) is a prevalent and often underrecognized problem in mechanically ventilated patients. Ventilator waveform analysis is a noninvasive and reliable means of detecting PVAs, but the use of this tool has not been broadly studied. MethodsOur observational analysis leveraged a validated evaluation tool to assess the ability of critical care practitioners (CCPs) to detect different PVA types as presented in three videos. This tool consisted of three videos of common PVAs (i.e., double-triggering, auto-triggering, and ineffective triggering). Data were collected via an evaluation sheet distributed to 39 hospitals among the various CCPs, including respiratory therapists (RTs), nurses, and physicians. ResultsA total of 411 CCPs were assessed; of these, only 41 (10.2%) correctly identified the three PVA types, while 92 (22.4%) correctly detected two types and 174 (42.3%) correctly detected one; 25.3% did not recognize any PVA. There were statistically significant differences between trained and untrained CCPs in terms of recognition (three PVAs, p < 0.001; two PVAs, p = 0.001). The majority of CCPs who identified one or zero PVAs were untrained, and such differences among groups were statistically significant (one PVA, p = 0.001; zero PVAs, p = 0.004). Female gender and prior training on ventilator waveforms were found to increase the odds of identifying more than two PVAs correctly, with odds ratios (ORs) (95% confidence intervals [CIs]) of 1.93 (1.07–3.49) and 5.41 (3.26–8.98), respectively. Profession, experience, and hospital characteristics were not found to correlate with increased odds of detecting PVAs; this association generally held after applying a regression model on the RT profession, with the ORs (95% CIs) of prior training (2.89 [1.28–6.51]) and female gender (2.49 [1.15–5.39]) showing the increased odds of detecting two or more PVAs. ConclusionCommon PVAs detection were found low in critical care settings, with about 25% of PVA going undetected by CCPs. Female gender and prior training on ventilator graphics were the only significant predictive factors among CCPs and RTs in correctly identifying PVAs. There is an urgent need to establish teaching and training programs, policies, and guidelines vis-à-vis the early detection and management of PVAs in mechanically ventilated patients, so as to improve their outcomes.

Virtual Migration with the Help of Cloud Simulator to Balance the Data Load

There are various techniques which are giving the solid issues with virtualization like the mode the type and the format of the data between the clients and services and data between services to services. This could lead the data loss and to solve this issue when virtualization the data has to be properly extracted and from the various selected extensions. So this work proposed a new framework with respect to API called personal virtualization application process interface API(PVA). This PVA is platform unspecific and can be utilized over the clouds and across the clouds with virtualization. Generally over the clouds if any data accommodation issues comes into scenario then the data migration can happen with the help of “extension dynamic creation”(EDC) of virtual machine making and data storage can happen in that new virtual machine with out any data loss. The EDC will preserve the data with out any duplication and stores in the virtualized machine. The threshold is based on the data storage capacity of the virtual machine which is allocated from cloud sim when allocation of cloudlets. The data selection process is dynamic and extraction of the solid data in the form PVA and same type of the data model will be maintained throughout the communication when virtualization happens. Now the data migration is safe when compared to the previous works which has no proper allocation of the data formats and extraction.

Strength Improvement of NC-SwBKP Sheets with PAE-PVA Pre-mixed Complexes (II): Effect of Types of PVA

Strength Improvement of NC-SwBKP Sheets with PAE-PVA Pre-mixed Complexes (II): Effect of Types of PVA

Development of Antioxidant Film Based on Blends of Stenochlaena palustris Flour and Poly(Vinyl Alcohol)

The aim of this work is to develop antioxidant films based on blends of Stenochlaena palustris flour and poly(vinyl alcohol) (PVA). Four different PVA types were tested. All films produced were analyzed for their antioxidant activity by diphenyl-picrylhydrazyl radical scavenging (DPPH) method. This study found that S. palustris flour-88% HD PVA blends film contains the highest antioxidant activity. The efficiency study of the film shows the EC50, TEC50 and Antioxidant Efficiency value of 20 mg/ml, 55 min and 0.91×10−3 respectively. The use of low concentration PVA and addition of glycerol made the film more flexible with greater elongation at break but low tensile strength. The formation of hydrogen bonds between the blend components was confirmed by the FTIR spectra analysis. The thermogravimetric analysis shows the thermal degradation of the film produced.

Investigation of the properties of Ni(OH)2 electrochrome films obtained in the presence of different types of polyvinyl alcohol

Electrochromic films were prepared by cathodic template synthesis in the presence of two types of polyvinyl alcohol: with the hydrolysis degree of 99 % and 85 %. The prepared films show differences in structural, morphological, electrochromic and electrochemical characteristics. Both films were X-ray amorphous and had different shapes of the curve on the XRD patterns in the region of small 2q angles, which corresponds to differences in the direction of 001. Comparison of the morphology of the films prepared from solutions containing PVA with different hydrolysis degrees revealed that the film prepared in the presence of 99 % hydrolyzed PVA has a relatively flat relief with small sizes of bumps. On the other hand, the film prepared in the presence of 85 % hydrolyzed PVA had worse uniformity. Its relief had wavy lines, the height of which reached 1.2 µm. Cyclic voltammograms of both films were also different. CVA of the film prepared in the presence of 85 % hydrolyzed PVA had sharp anodic and cathodic peaks that are similar in height. The potentials of the peaks were +600 and +700 mV. The film prepared in the presence of 99 % hydrolyzed PVA showed broader peaks, with the anodic peak shifted to more positive values (+900 mV). Electrochromic characteristics of both films also differed significantly. The film deposited in the presence 85 % hydrolyzed PVA had a high coloration rate (60 s), but lower coloration degree (18 %). On the other hand, the film deposited in the presence of 99 % hydrolyzed PVA had a coloration rate that is three times slower (200 s), but higher absolute coloration degree (24 %). Several mechanisms that explain such differences in the behavior of the films prepared in the presence of different PVA types have been proposed.

Aqueous solution blow spinning of poly(vinyl alcohol) micro- and nanofibers

This work addresses the challenge to produce fibers from the water-soluble polymer poly(vinyl alcohol) (PVA), using solution blow spinning (SBS) with forced solvent evaporation at the point of fiber formation. PVA at two different molecular weights, with different degrees of acetylation, were successfully blow spun into nano- and micro-fiber membranes, across a range of concentrations in water (12–20w/v%). Fiber spinnability, morphology and size are correlated to precursor solution viscosity and PVA type. PVA with degree of polymerization 1100 and degree of hydrolysis 98–99% was relatively facile to spin into fibers. Difficulties in spinning high molecular weight PVA were overcome by introducing hot air at the point of fiber formation to force water evaporation. The procedure developed here opens SBS to other aqueous-based polymer and composite systems for environmentally benign fiber and membrane formation.

Influence of poly(vinyl alcohol) molecular weight on drop coalescence and breakage rate

The influence of poly(vinyl alcohol), PVA, molecular weight on drop breakage and coalescence in stirred liquid–liquid dispersion was considered. Three types of PVA of the same degree of hydrolysis 88% and different molecular weights in the range 13,000–186,000 were used in experiments. Molecular weight affects steric forces, interfacial tension and surface viscosity, which all have an influence on drop size distribution. PVA of lower molecular weight reduces the interfacial tension more effectively while the adsorption of high molecular weight PVA is slower and more complicated. Drop interfaces can remain partially mobile for polymer concentration as small as 0.001wt% or they can be significantly immobilized for PVA concentration c≥0.002wt%. Drop size distributions were predicted using multifractal breakage and coalescence models. Lost of stabilizing properties of PVA of highest molecular weight at high impeller speed was observed which can be explained by unfavorable molecule conformation in such conditions.

Tunable Mechanics in Electrospun Composites via Hierarchical Organization.

Design strategies from nature provide vital clues for the development of synthetic materials with tunable mechanical properties. Employing the concept of hierarchy and controlled percolation, a new class of polymer nanocomposites containing a montmorillonite (MMT)-reinforced electrospun poly(vinyl alcohol) (PVA) filler embedded within a polymeric matrix of either poly(vinyl acetate) (PVAc) or ethylene oxide-epichlorohydrin copolymer (EO-EPI) were developed to achieve a tunable mechanical response upon exposure to specific stimuli. Mechanical response and switching times upon hydration were shown to be dependent on the weight-fraction of MMT in the PVA electrospun fibers and type of composite matrix. PVA/MMT.PVAc composite films retained excellent two-way switchability for all MMT fractions; however, the switching time upon hydration was decreased dramatically as the MMT content was increased due to the highly hydrophilic nature of MMT. Additionally, for the first time, significant two-way switchability of PVA/MMT.EO-EPI composites was achieved for higher weight fractions (12 wt %) of MMT. An extensive investigation into the effects of fiber diameter, crystallinity, and MMT content revealed that inherent rigidity of MMT platelets plays an important role in controlling the mechanical response of these hierarchical electrospun composites.

Parasternal electromyography to determine the relationship between patient-ventilator asynchrony and nocturnal gas exchange during home mechanical ventilation set-up

IntroductionPatient-ventilator asynchrony (PVA) can adversely affect the successful initiation of non-invasive home mechanical ventilation (HMV). The aim of this observational study was to quantify the prevalence of PVA during initiation...

PVA 중합도가 고상-액상 혼합 방식에 의한 YAG:Ce3+형광체 분말 합성에 미치는 영향

YAG:Ce 3+ phosphor powders were synthesized using Al(OH)₃ seeds by means of a PVA-polymer-solution route. Various types of PVA with different molecular weights (different polymerization) were used. All dried precursor gels were calcined at 500°C and then heated at 1500°C in a mix of nitrogen and hydrogen gases. The final powders were characterized via XRD, SEM, PSA, PL, and PKG analyses. The phosphor properties and morphologies of the synthesized powders were dependent on the PVA type. As the molecular weight of the PVA was increased, the particle size gradually decreased with agglomeration, and the luminous intensity of the phosphor increased. However, the phosphor powder prepared from the PVA exhibiting very high molecular weight, showed a 531 nm (blue) shift from the 541 nm (yellow) wavelength of the YAG:Ce 3+ phosphor. Finally, the synthesized YAG:Ce 3+ phosphor powder prepared from the PVA with 89,000 - 98,000 molecular weight showed phosphor properties similar to those of a commercial phosphor powder, but without a post-treatment process.

Patient ventilator asynchrony in critically ill adults: Frequency and types

BackgroundPatient ventilator asynchrony (PVA) occurs frequently, but little is known about the types and frequency of PVA. Asynchrony is associated with significant patient discomfort, distress and poor clinical outcomes (duration of mechanical ventilation, intensive care unit and hospital stay). MethodsPressure–time and flow–time waveform data were collected on 27 ICU patients using the Noninvasive Cardiac Output monitor for up to 90 min per subject and blinded waveform analysis was performed. ResultsPVA occurred during all phases of ventilated breaths and all modes of ventilation. The most common type of PVA was Ineffective Trigger. Ineffective trigger occurs when the patient's own breath effort will not trigger a ventilator breath. The overall frequency of asynchronous breaths in the sample was 23%, however 93% of the sample experienced at least one incident of PVA during their observation period. Seventy-seven percent of subjects experienced multiple types of PVA. ConclusionsPVA occurs frequently in a variety of types although the majority of PVA is ineffective trigger. The study uncovered previously unidentified waveforms that may indicate that there is a greater range of PVAs than previously reported. Newly described PVA, in particular, PVA combined in one breath, may signify substantial patient distress or poor physiological circumstance that clinicians should investigate.