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The electrospinning of cellulose acetate (CA) was investigated to develop biodegradable nanostructured membranes for the controlled release of drugs used to treat skin wounds. CA nanofibers were successfully prepared via the electrospinning in the four mixed solvents acetic acid : water; acetone : water; DMAc : acetone; DMAc : acetone : water. Design of experiments (DOE) was applied to see what combinations of parameters could affect the production of electrospun microfibers and nanofibers to optimize the process. The results of this work indicated that both the processing parameters and the solvent mixtures were responsible for the fiber diameter and nanostructure membrane appearance. The optimized condition for each solvent mixture was obtained and compared with each one of the others. The best conditions achieved were dimethylacetamida (DMAc) : acetone with 17% of CA, which provided homogeneous and free bead fibers with an average diameter of 295 nm. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 [ABSTRACT FROM AUTHOR]

Summary The taxonomy of 58 locally isolated antibiotic- and enzyme-producing Bacillus isolates deposited at the Philippine National Collection of Microorganisms (PNCM)-BIOTECH was reassessed in this study using a polyphasic approach since they had been only partially identified prior to deposition in the culture collection. The isolates had 41.1–69% G + C, and possessed the characteristic diaminopimelic acid (DAP) and fatty acid methyl ester (FAMEs) properties of Bacillus species. Molecular analysis using specific PCR primers differentiated the isolates into two major groups, the Bacillus cereus group and the Bacillus subtilis group. To further differentiate these isolates, they were subjected to 39 phenotypic tests. Using the dichotomous key constructed for Bacillus, 45 isolates maintained their original identities, five were named at the species level, and 12 were re-identified and renamed. These results showed that the classical phenotypic tests allowed the reclassification of the isolates, while modern techniques of chemotaxonomy and the molecular approach led only to genus and cluster classification and confirmation. [ABSTRACT FROM AUTHOR]

Summary At present, observational studies and expert opinion are the best evidence for the use of physical restraints. Large regional and national disparities are described in acute and long-term care. Epidemiological data demonstrate a prevalence of 35% body-fixed or near body restraint devices. The hip fracture rate in Germany are approximately 50 per 1000 resident years. Between 4050% of the residents in nursing homes are treated with psycho-tropic medication potentially limiting their physical mobility. The presented study protocol was designed to test the effectiveness of a multifactorial intervention to reduce physical restraints in long-term care (LTC) residents particularly with cognitive impairment. The intervention consists of an educational and an organizational part to empower staff members to improve their skills and practice in using restraints. Technical devices to reduce fall related injuries are additionally offered to the LTC facilities. The study population includes 200 LTC residents in 54 facilities in three states in Germany. The samle size calculation was based upon a 5% prevalence rate in the control group and an expected reduction of 50% in the intervention group. The protocol is a waiting-list control design. All waiting facilities will be offered to participate after their waiting period. Primary endpoints are the number of restrained residents and resident time (hours) of being restrained. The use of psychotropics, falls, fall-related injuries and the incidence of residents newly being restrained is being monitored. The study starts with a baseline documentation of all facilities followed by randomization and a three month intervention. Change agents will be responsible for the intervention. Technical devices will include a newly developed soft hip protector and sensor mats which notice the intent of leaving the bed. The aim of the study is to develop an evidence-based model for a knowledge transfer project to implement minimum restraint environments in LTC. [ABSTRACT FROM AUTHOR]

Background: Many patients with gallstone disease continue to report gastrointestinal symptoms after cholecystectomy, but the predictive value of preoperative factors is not well understood. We aimed to investigate whether psychological symptoms can be associated with poor outcome after cholecystectomy in patients with gallstones and dyspepsia. Methods: A sample of 52 consecutive patients with uncomplicated gallstone disease and dyspepsia (conceived in a broader sense to include symptoms of the whole digestive tract) were assessed for psychological (revised 90-item Hopkins Symptom Checklist) and gastrointestinal symptoms (Gastrointestinal Symptom Rating Scale). One year after laparoscopic cholecystectomy, patients rated their gastrointestinal symptoms and were divided into improved and unimproved on the basis of the change in symptoms. Results: Twenty-one (40.4%) patients did not improve after surgery. Improved and unimproved patients did not differ in terms of sex, age, education or illness duration. Unimproved patients showed significantly higher psychological and dyspeptic symptoms than improved patients before surgery. Logistic regression showed that psychological factors were significantly associated with unimprovement after surgery. Conclusions: Patients with gallstone disease and dyspeptic symptoms are unlikely to improve 1 year after surgery if they show psychological distress before surgery. Psychological symptoms were strongly associated with poor post-cholecystectomy outcome, thus highlighting the clinical relevance of joint assessment of psychological and gastrointestinal symptoms before surgery. [ABSTRACT FROM AUTHOR]

This work explores the effect of nitrogen addition on CO2 dissociation under various non-equilibrium plasma conditions. Experiments are performed in non-thermal plasmas sustained by DC pulsed discharges, for pressure and current ranges of 1 to 5 Torr and 20 to 50 mA, respectively. A self-consistent model, previously validated for pure CO2 discharges, is further extended to take into account e-V, V-T and V–V reactions involving N2. Both model predictions and experimental data reveal a maximum of the asymmetric vibrational temperature T3 at 5 Torr during the discharge around 1 ms, while no such maximum is visible at 1 Torr before the saturation occurs. It is shown that V-T deactivation by O atoms can have a strong influence on the vibrational kinetics, by directly affecting the relaxation of N2 vibrational excited states and, as a consequence, the very important energy transfers between vibrationally excited N2 and CO2 molecules. The experimental results show a twice as large CO2-conversion rate when N2 gas is added to the plasma. The simulations suggest this effect cannot be the result of an increased dissociation by direct electron impact due to modifications in the reduced electric field, but rather of some other contribution to dissociation and/or inhibition of reactions giving back CO2. [ABSTRACT FROM AUTHOR]

This work employs in situ rotational Raman spectroscopy to study the effect of N2 and O2 addition to CO2 in pulsed glow discharges in the mbar range. The spatiotemporally resolved measurements are performed in CO2 and 25%, 50% and 75% of N2 or O2 admixture, in a 5–10 ms on-off cycle, 50 mA plasma current and 6.7 mbar total pressure. The rotational temperature profile is not affected by adding N2, ranging from 400 to 850 K from start to end of the discharge pulse, while the addition of O2 decreases the temperature at corresponding time points. Molecular number densities of CO2, CO, O2 and N2 are determined, showing the spatial homogeneity along the axis of the reactor and uniformity during the cycle. The measurements in the N2 containing mixtures show that CO2 conversion factor α increases from 0.15 to 0.33 when the content of N2 is increased from 0% to 75%, demonstrating the potential of N2 addition to enhance the vibrational pumping of CO2 and its beneficial effect on CO2 dissociation. Furthermore, the influence of admixtures on CO2 vibrations is examined by analysing the vibrationally averaged nuclear spin degeneracy. The difference between the fitted odd averaged degeneracy and the calculated odd degeneracy assuming thermal conditions increases with the addition of N2, demonstrating the growth of vibrational temperatures in CO2. On the other hand, the addition of O2 leads to a decrease of α, which might be attributed to quenched vibrations of CO2, and/or to the influence of the back reaction in the presence of O2. [ABSTRACT FROM AUTHOR]

The LisbOn KInetics Boltzmann (LoKI-B) is an open-source simulation tool (https://github.com/IST-Lisbon/LoKI) that solves a time and space independent form of the two-term electron Boltzmann equation, for non-magnetised non-equilibrium low-temperature plasmas excited by DC/HF electric fields from different gases or gas mixtures. LoKI-B was developed as a response to the need of having an electron Boltzmann solver easily addressing the simulation of the electron kinetics in any complex gas mixture (of atomic/molecular species), describing first and second-kind electron collisions with any target state (electronic, vibrational and rotational), characterized by any user-prescribed population. LoKI-B includes electron-electron collisions, it handles rotational collisions adopting either a discrete formulation or a more convenient continuous approximation, and it accounts for variations in the number of electrons due to non-conservative events by assuming growth models for the electron density. On input, LoKI-B defines the operating work conditions, the distribution of populations for the electronic, vibrational and rotational levels of the atomic/molecular gases considered, and the relevant sets of electron-scattering cross sections obtained from the open-access website LXCat (http://lxcat.net/). On output, it yields the isotropic and the anisotropic parts of the electron distribution function (the former usually termed the electron energy distribution function), the electron swarm parameters, and the electron power absorbed from the electric field and transferred to the different collisional channels. LoKI-B is developed with flexible and upgradable object-oriented programming under MATLAB®, to benefit from its matrix-based architecture, adopting an ontology that privileges the separation between tool and data. This topical review presents LoKI-B and gives examples of results obtained for different model and real gases, verifying the tool against analytical solutions, benchmarking it against numerical calculations, and validating the output by comparison with available measurements of swarm parameters. [ABSTRACT FROM AUTHOR]

A consistent theoretical analysis of a pulsed DC glow discharge operating at pressure of 5 Torr, current of 50 mA and plasma pulse of 5 ms in CO2 is presented. The model couples the electron Boltzmann equation to a rate balance equations involving ~70 individual vibrational states. The kinetic scheme and the corresponding e–V, V–T and V–V rate coefficients are validated via comparison between the model predictions and recent experimental data available in literature. The bending and symmetric vibrational levels show a continuous increase along the plasma pulse while the levels in the asymmetric mode present a maximum at around 0.7 ms. A corresponding maximum of the temperature of the asymmetric stretch vibration mode is observed as well at the start of the pulse reaching a value of about 900 K, well above the vibrational temperatures of the symmetric and bending modes, which remain always nearly equilibrated. A quick thermalization of the CO2 vibrational temperatures is always observed in the afterglow. [ABSTRACT FROM AUTHOR]

This is the second of two papers presenting the study of vibrational energy exchanges in non-equilibrium CO2 plasmas in low-excitation conditions. The companion paper addresses a theoretical and experimental investigation of the time relaxation of ∼70 individual vibrational levels of ground-state CO molecules during the afterglow of a pulsed DC glow discharge, operating at pressures of a few Torr and discharge currents around 50 mA, where the rate coefficients for vibration–translation (V–T) and vibration–vibration (V–V) energy transfers among these levels are validated (Silva et al 2018 Plasma Sources Sci. Technol.27 015019). Herein, the investigation is focused on the active discharge, by extending the model with the inclusion of electron impact processes for vibrational excitation and de-excitation (e-V). The time-dependent calculated densities of the different vibrational levels are compared with experimental data obtained from time-resolved in situ Fourier transform infrared spectroscopy. It is shown that the vibrational temperature of the asymmetric stretching mode is always larger than the vibrational temperatures of the bending and symmetric stretching modes along the discharge pulse—the latter two remaining very nearly the same and close to the gas temperature. The general good agreement between the model predictions and the experimental results validates the e-V rate coefficients used and provides assurance that the proposed kinetic scheme provides a solid basis to understand the vibrational energy exchanges occurring in CO2 plasmas. [ABSTRACT FROM AUTHOR]

This work explains the need for plasma models, introduces arguments for choosing the type of model that better fits the purpose of each study, and presents the basics of the most common nonequilibrium low-temperature plasma models and the information available from each one, along with an extensive list of references for complementary in-depth reading. The paper presents the following models, organised according to the level of multi-dimensional description of the plasma: kinetic models, based on either a statistical particle-in-cell/Monte-Carlo approach or the solution to the Boltzmann equation (in the latter case, special focus is given to the description of the electron kinetics); multi-fluid models, based on the solution to the hydrodynamic equations; global (spatially-average) models, based on the solution to the particle and energy rate-balance equations for the main plasma species, usually including a very complete reaction chemistry; mesoscopic models for plasma–surface interaction, adopting either a deterministic approach or a stochastic dynamical Monte-Carlo approach. For each plasma model, the paper puts forward the physics context, introduces the fundamental equations, presents advantages and limitations, also from a numerical perspective, and illustrates its application with some examples. Whenever pertinent, the interconnection between models is also discussed, in view of multi-scale hybrid approaches. [ABSTRACT FROM AUTHOR]

A kinetic model describing the time evolution of ∼70 individual CO2(X1Σ+) vibrational levels during the afterglow of a pulsed DC glow discharge is developed in order to contribute to the understanding of vibrational energy transfer in CO2 plasmas. The results of the simulations are compared against in situ Fourier transform infrared spectroscopy data obtained in a pulsed DC glow discharge and its afterglow at pressures of a few Torr and discharge currents of around 50 mA. The very good agreement between the model predictions and the experimental results validates the kinetic scheme considered here and the corresponding vibration–vibration and vibration–translation rate coefficients. In this sense, it establishes a reaction mechanism for the vibrational kinetics of these CO2 energy levels and offers a firm basis to understand the vibrational relaxation in CO2 plasmas. It is shown that first-order perturbation theories, namely, the Schwartz–Slawsky–Herzfeld and Sharma–Brau methods, provide a good description of CO2 vibrations under low excitation regimes. [ABSTRACT FROM AUTHOR]

This work presents an experimental study of microwave (2.45 GHz excitation frequency) micro-plasmas, generated in dry air (N2 80%: O2 20%) within a small radius silica capillary (345 µm inner radius) at low pressure (300 Pa) and low powers (80–130 W). Experimental diagnostics are performed using optical emission spectroscopy calibrated in absolute intensity. Axial-resolved measurements (50 µm spatial resolution) of atomic transitions N(3p4S)  →  N(3s4P); O(3p5P)  →  O(3s5S) and molecular transitions N2(C,v′)  →  N2(B,v″); (B,v′)  →  (X,v″) allow us to obtain, as a function of the coupled power, the absolute densities of N(3p4S), O(3p5P), N2(C), N2(B) and (B), as well as the gas (rotational) temperature (700–1000 K), the vibrational temperature of N2(C,v) (7000–10 000 K) and the excitation temperatures of N2(C) and N2(B) (11 000 K). The analysis of the Hβ line-width gives an upper limiting value of 1013 cm−3 for the electron density; its axial variation (4  ×  1011–6  ×  1012 cm−3) being estimated by solving the wave electrodynamics equations for the present geometry, plasma length and electron–neutral collision frequency. The experimental results were compared with the results from a 0D model, presented in companion paper I [1], which couples the system of rate balance equations for the dominant neutral and charged plasma species to the homogeneous two-term electron Boltzmann equation, taking the measured gas temperature and the estimated electron density as input parameters. Good qualitative agreement is found between the measurements and calculations of the local species densities for various powers and axial positions. The dissociation degree of oxygen is found above 10%. Moreover, both the measurements and calculations show evidence of the non-equilibrium behavior of low-temperature plasmas, with vibrational and excitation temperatures at least ten times higher than the gas temperature. These observations confirm that low-pressure microwave micro-plasmas exhibit high-reactivity, and the present study shows that these features are controlled by electron kinetics, as expected. [ABSTRACT FROM AUTHOR]

This work presents the self-consistent modeling of micro-plasmas generated in dry air using microwaves (2.45 GHz excitation frequency), within capillaries (<1 mm inner radius) at low pressure (300 Pa). The model couples the system of rate balance equations for the most relevant neutral and charged species of the plasma to the homogeneous electron Boltzmann equation. The maintenance electric field is self-consistently calculated adopting a transport theory for low to intermediate pressures, taking into account the presence of O− ions in addition to several positive ions, the dominant species being O, NO+ and O+ . The low-pressure small-radius conditions considered yield very-intense reduced electric fields (∼600–1500 Td), coherent with species losses controlled by transport and wall recombination, and kinetic mechanisms strongly dependent on electron-impact collisions. The charged-particle transport losses are strongly influenced by the presence of the negative ion, despite its low-density (∼10% of the electron density). For electron densities in the range (1– cm−3, the system exhibits high dissociation degrees for O2 (∼20–70%, depending on the working conditions, in contrast with the  ∼0.1% dissociation obtained for N2), a high concentration of O2(a) (∼1014 cm−3) and NO(X) ( cm−3) and low ozone production (<). [ABSTRACT FROM AUTHOR]

Surface-wave discharges in argon at atmospheric pressure were experimentally studied by optical emission spectroscopy (OES) and mass spectrometry (MS). OES was employed to determine the rotational temperature using the ultraviolet OH band, Q1 branch and found to be between 450 and 970 K. The electron density (5   ×   1013 cm−3  ≤  ne  ≤  7   ×   1014 cm−3) was estimated using the Hβ line profile, and produced by dissociation of the water present as an impurity in the Ar gas. The electron temperature (0.63 eV  ≤  Te  ≤  1.3 eV) was estimated using a collisional–radiative (CR) model that takes the input measured intensities of four emission lines originating from 2p states including 2p2, 2p4, 2p6, and 2p10. The density of the metastable state Ar(1s5) (2.0   ×   1011 cm−3  ≤  Ar(1s5)  ≤  4.2   ×   1012 cm−3) was estimated by means of OES using the self-absorbing method. Positive and negative ions were probed along the plasma column using MS. A theoretical model based on the solution of the homogeneous electron Boltzmann equation, considering inelastic and superelastic collisions with the Ar(1s) states and electron–electron collisions, coupled with a system of rate balance equations describing the creation and destruction of the most important heavy particles, is proposed. The experimental results are compared with theoretical ones obtained from a self-consistent model of these discharges, providing physical insight into the basic mechanisms and phenomena ruling the discharges. [ABSTRACT FROM AUTHOR]

The homogeneous Boltzmann equation for electrons in N2, O2 and H2 is solved under the classical two-term approximation, for reduced electric fields in the interval 10  −  4  −10 Td where the electron-neutral encounters are limited to elastic, rotational and vibrational collisions. Rotational excitations/de-excitations are described using the following three different approaches: the discrete inelastic/superelastic collisional operator, written for a number of rotational levels that depends on the molecular gas and the specific rotational cross sections considered; the continuous approximation for rotations; a modified version of the continuous approximation for rotations, including a Chapman–Cowling corrective term proportional to the gas temperature. The expression of the rotational collision operator for this latter approach is deduced here and the results show that it bridges the gap between the discrete and the continuous descriptions at low/intermediate reduced electric fields. The calculations are compared with the measurements for the available swarm parameters to assess the validity of the different approaches and cross sections adopted to describe the rotational mechanisms. [ABSTRACT FROM AUTHOR]

A kinetic model is developed to study the afterglow plasma of a pulsed discharge in air. This model includes a detailed analysis of the temporal evolution of heavy species during the pulse, followed by their relaxation in the afterglow. The predicted results are compared with two experimental sets performed in the time afterglow of a pulsed discharge in N2-20%O2 at a pressure p = 133 Pa involving the measurements of (i) N2(B) and N2(C) fluorescences for a discharge current I = 40 mA and a pulse duration t = 200 us and 10 ms, together with (ii) the absolute concentration of NO(X) for I = 40 and 80 mA with t varying from 1 to 4 ms. The results of the model agree reasonably well with the measurements of N2(B) and N2(C) decays. It is shown that under these experimental conditions, N2(B) is always populated mainly via the process N2(A) + N2(X, 5 [?] v [?] 14) - N2(B) + N2(X, v = 0), while the relaxation of N2(C) is dominated by the pooling reaction N2(A) + N2(A) - N2(C) + N2(X, v = 0). An almost constant concentration of NO(X) is experimentally observed until the remote afterglow, but the present model is only capable of predicting the same order of magnitude for afterglow times t [?] 0.05 s. Several hypotheses are discussed and advanced in order to explain this discrepancy. [ABSTRACT FROM AUTHOR]