Premix Solution Research Articles

Efficacy and safety of greater occipital nerve block with a small volume of lidocaine and methylprednisolone in tertiary headache center

Background: The greater occipital nerve block (GON-B) is used in clinical practice for treating different forms of headache. There is no standardized procedure to perform GON-B. This study evaluates the efficacy and feasibility of a low-volume GON-B protocol utilizing a pre-mixed solution of lidocaine (10 mg) and methylprednisolone (40 mg) across various headache disorders. Methods: This observational case series included patients receiving their first GON-B from November 2019 to February 2021. Participants were diagnosed with migraine, cluster headache, cervicogenic headache, or paroxysmal hemicrania. The primary outcome was the degree of response to the GON-B. Results: Thirty-nine patients with migraine underwent a first GON-B. Regarding headache frequency, 26% achieved substantial response and 33% partial response. For headache intensity, 26% reported substantial and 49% partial improvement. Migraine patients experienced a significant reduction in median monthly headache days from 25 to 13 (p=0.001) and in headache intensity from a median of 8 to 6 on the Numerical Rating Scale (NRS) scale (p<0.001). Of the 27 patients receiving a second GON-B, 33% had a substantial response, 48% a partial response, and 19% no response. Results from subsequent sessions were consistent with these findings. Ten patients with cluster headache underwent GON-B, showing a significant reduction in pain intensity from a median NRS score of 10 to 5 (p=0.008). Two patients with cervicogenic headache showed a partial response to GON-B, with pain intensity decreasing from 8 to 6 and 8 to 7 over 30 monthly episodes. A patient with paroxysmal hemicrania received seven GON-B injections, reducing daily attacks from 30 to 10 and pain intensity from 7 to 6 on the NRS scale. Conclusions: These outcomes affirm GON-B potential in interrupting pain pathways, even at a low dose, in a wide range of headache disorders.

Evaluation of the methacrylamide/ N’N,-methylenebisacrylamide gel binder system for gel-casting of titanium powder

Gel-casting, a near-net-shape manufacturing technique developed for ceramic powder processing, is investigated to produce titanium parts. In this study, the MAM/MBAM gel-binder system is used to develop a suitable slurry formulation and gel-casting procedure for commercially pure titanium powder. The polymeric binder system was evaluated by altering process parameters to produce a stable slurry of uniformly dispersed titanium powder that resists particle settling. Stable slurry formulations are gel-cast into rectangular bars to evaluate the green properties. The suitability of the binder system was studied by evaluating the gelation time and settling behaviour of the slurry for three dispersants at concentrations up to 0.6 wt% of the titanium powder, a range of MAM:MBAM ratios from 3:1 to 15:1 and monomer concentrations from 17 to 40 wt% of the premix solution. The green density and strength were evaluated for bars that were gel-cast from slurries with 37 vol% solids loading, 0.6 wt% Dolapix CE64 dispersant, a MAM:MBAM ratio of 3:1 and a monomer concentration of 23, 29 and 37 wt% in the premix solution. The 37 wt% monomer concentration gel-cast titanium bar produced the highest green density, 2.50 g/cm3 (55% relative density), with density gradients varying less than 4% from this average within the green part. This formulation also produced the highest green strength of 8.92 MPa.

The effect of a methadone reformulation on opioid agonist treatment outcomes: A population-based study in British Columbia, Canada, 2013–14

IntroductionThe province of British Columbia, Canada, changed the existing oral anhydrous methadone solution to a 10-times more concentrated pre-mixed solution, Methadose®, on February 1, 2014. We aimed to assess the immediate effects of the methadone reformulation on missed doses, days off methadone, changes in medication dosing and dispensations of opioids for pain, and hospitalizations and mortality among all people receiving treatment at or near the time of the change. MethodsWe conducted a population-based retrospective cohort study including all individuals receiving at least one methadone dispensation in the 12 months prior to the study period. We executed a difference-in-differences analysis by estimating a multivariate regression model to compare outcomes in the three months before and after the reformulation (November 1, 2013 to April 30, 2014) versus a time-lagged control cohort with similar characteristics observed during an equivalent nonoverlapping interval. We used daily individual-level linked health administrative data capturing missed doses, days off methadone, changes in methadone dosing, concurrent dispensations of opioids for pain, hospitalizations, and mortality. We stratified the cohorts into three subgroups: (i) those receiving OAT for ≥12 months; (ii) those receiving OAT for <12 months; and (iii) those not receiving OAT at the start of the study period. We conducted sensitivity analyses and placebo tests to assess the robustness of our results. ResultsAmong the 16,339 individuals receiving methadone during the study period, the reformulation was associated with more instances of methadone dose increases (34.5% [95% Confidence Interval (CI): 27.4%, 41.5%]). For those retained in treatment ≥12 months prior to the study period (n = 7449), the reformulation was associated with more instances of methadone dose increases (50.2% [39.5%, 60.8%]) and dispensations of opioids for pain (62.2% [40.8%, 83.5%]), as well as an increase in missed doses (41.9% [29.1%, 54.7%]) and days off methadone (62.6% [39.7%, 85.4%]). We found no statistically significant change in risk of hospitalization or mortality. Sensitivity analyses supported our results. ConclusionOur results reinforce the need expressed by people receiving methadone for greater client involvement in the planning and implementation of regulatory changes that may impact client care, especially those patients with a relatively long treatment history.

Should we be concerned about histologic changes caused by novel submucosal injection agents used for EMR and ESD?

Normal saline mixed with dyes is a widely used submucosal lifting agent for endoscopic resection of small gastrointestinal (GI) lesions. For larger GI lesions, novel agents are used to achieve optimal results. ORISE gel is a novel, premixed submucosal lifting solution for endoscopic resection procedures. The initial histologic appearance of endoscopic specimens with injection of ORISE gel is characterized by a pale, basophilic amorphous appearance which has the potential to be misinterpreted as a pathologic finding. The histologic appearance changes overtime to an eosinophilic appearance that is reflected by an inflammatory, foreign body reaction.&#x0D; We summarize the @GIJournal discussion held on May 12, 2021, about the article by Olivas et al “Histologic changes caused injection of a novel submucosal lifting agent for endoscopic resection in GI lesions” 1. The guest experts to discuss pathology included Drs. Emma Furth (EF), and Pallavi Patil (PP), the discussion was moderated by Dr. Dmitriy Kedrin (DK).

Growth Mechanisms of Nano-to Micro-Sized Lead Sulfate Particles.

PbSO4 is a key component in the charging and discharging of lead acid batteries—such as the cycling of automotive batteries. PbSO4 is a poor conductor that forms on the positive and negative electrodes during discharging and dissolves during charging of a lead acid battery. Over time, buildup of PbSO4 occurs on the electrodes, ultimately reducing the efficiency of the battery. This study aims to determine the nucleation and growth mechanisms of PbSO4 nanoparticles in various solutions to potentially reduce or control the buildup of PbSO4 on battery electrodes over time. The time dependency of particle morphology was observed using various reaction conditions. PbSO4 particles were created using premixed solutions at various times of reaction. H2O, acetone, methanol, ethanol, and isopropanol were used to stop the reaction and development of the PbSO4 particles. The structure of the nanoparticles was characterized via transmission electron microscopy, high-angle annular dark field scanning transmission electron microscopy, and selected area electron diffraction. This study provides insight into the mechanism by which PbSO4 nanoparticles form in various solutions and reveals that the degree of complexity of the solution plays a large role in the nucleation and growth of the PbSO4 nanoparticles. This insight can provide avenues to reduce unwanted buildup of PbSO4 on battery electrodes over time, which can extend battery life and performance.

Sugar, a powerful substitute for ethanol in ethanol postdependent rats: Relevance for clinical consideration?

Sugar has been shown to be a powerful substitute for drugs in preclinical studies on addiction. However, the link between sugar intake and alcohol use disorder (AUD) is poorly understood. We assessed the influence of sucrose on ethanol drinking in both nondependent (ND) and dependent (D) Long-Evans rats during acute withdrawal using the postdependent state model. Ethanol (10%-40%) and sucrose (1%-4%) solutions were offered in an operant paradigm either independently or concurrently under ratio schedules of reinforcement. We showed that D rats displayed an enhanced motivation for both 10% ethanol solution (10E) and 4% sucrose solution (4S) as compared with ND rats, and a clear preference for 4S was observed in both groups. During acute withdrawal, D rats showed a strong motivation for 30% ethanol (30E), even when adulterated with quinine, but still preferred 4S despite the fact that a high level of negative reinforcement could be expected. However, when a premix solution (30E4S) was offered concurrently with 4S, the preference for 4S was lost in D animals, which consumed as much premix as 4S, whereas ND animals displayed preference for 4S. Altogether, those results suggest that reinforcing properties of sucrose surpass those of ethanol in D rats under acute withdrawal, which indicates that sugar is a powerful substitute for ethanol. Our results suggest that craving for sugar may be increased in AUD patients during withdrawal and raise the issue of dependence transfer from alcohol to sugar.

Compatibility of aqueous film-forming foams (AFFF) with sea water

This contribution combines the observations from fire experiments with modelling of ionisation of fluorosurfactants to explain the compatibility of AFFF with sea water. We report detailed chemical structures of fluorosurfactants introduced into the firefighting foam market since the development of the so-called light water by the US Naval Research Laboratory (NRL) in late 1960s and study their ionisation constants (i.e., pKa). The analyses of recent formulations of foam concentrates indicate that, almost all of them include four species of high purity C6 fluorotelomer and non-fluorotelomer surfactants, which have their roots in fluorosurfactant chemistries developed by 3M, Ciba-Geigy and Elf Atochem (and its predecessors). The earliest fluorosurfactants emerged as derivatives of perfluorocarbon acyl and sulfonyl fluorides, from a series of discoveries made by the 3M Company. We review the foaming and filming technologies developed by 3M, derived from the products of electrochemical fluorination (ECF), comprising acidic, propane-sultone, acrylic and amine-oxide concentrates, with potassium perfluorooctane sulfonate (K-PFOS) filmers used together with the sultone and acrylic foamers. To the best of our knowledge, these chemistries have not been documented in one reference in the open literature, and some of the chemicals used have not yet been identified in the environment. While we do not cover the development of fluorotelomer chemistries in the same detail, we discuss the fluorotelomer surfactants that have proven themselves to be successful in compatibility with sea water and compare their structure with those of the ECF-derived chemicals. We discovered that, the chemical compatibility with sea water is related to the formation of the specific ionised species that combine with divalent alkaline-earth metal cations to form ionic assemblies in the premix (solution made by mixing foam concentrates with water). These species arise at high pH values that are characteristic of sea water. We also reveal that, changes in the ionisation state of amine-oxide and tertiary-amine head groups, as pH varies between that of fresh and sea-water premix, may impact the performance of fluorosurfactants. The physical compatibility of fluorosurfactants with sea water manifests itself by shielding of the ionised head groups by metal cations decreasing the surface tension and modifying the size, shape and diffusion of micelles. For foam concentrates that satisfy the necessary condition of chemically compatible with sea water, the physical effect usually improves the foam quality and the fire-suppression performance of AFFF. We analyse in detail the patent literature and the early NRL reports to gain an intimate understanding of the first formulations introduced by the 3M Company. Although PFOS has been banned internationally, Chinese manufacturers produce PFOS-type concentrates for the domestic market, in addition to fluorotelomer surfactants destined for export. We provide detailed formulations of all types of concentrates that employed the ECF-based fluorosurfactant technologies, including hydrocarbon surfactants, solvents, corrosion inhibitors and buffers and link the chemical composition of the concentrates with the firefighting performance of the foams. We outline the correlations between the ionisation states of fluorosurfactants and their fundamental properties, such as surface packing and interfacial tension and comment that very little is known about these critical structure-activity relationships. Finally, we stress the need to reboot the progress in the field and give directions for future research.

An Evidence for a Novel Antiviral Mechanism: Modulating Effects of Arg-Glc Maillard Reaction Products on the Phase Transition of Multilamellar Vesicles.

Maillard reaction products (MRPs) of protein, amino acids, and reducing sugars from many foods and aqueous extracts of herbs are found to have various bioactivities, including antiviral effects. A hypothesis was proposed that their antiviral activity is due to the interaction with the cellular membrane. Aiming to estimate the possible actions of MRPs on phospholipid bilayers, the Arg-Glc MRPs were prepared by boiling the pre-mixed solution of arginine and glucose for 60 min at 100°C and then examined at a series of concentrations for their effects on the phase transition of MeDOPE multilamellar vesicles (MLVs), for the first time, by using differential scanning calorimetry (DSC) and temperature-resolved small-angle X-ray scattering (SAXS). Arg-Glc MRPs inhibited the lamellar gel–liquid crystal (Lβ-Lα), lamellar liquid crystal–cubic (Lα-QII), and lamellar liquid crystal–inverted hexagonal (Lα-HII) phase transitions at low concentration (molar ratio of lipid vs. MRPs was 100:1 or 100:2), but promoted all three transitions at medium concentration (100:5). At high concentration (10:1), the MRPs exhibited inhibitory effect again. The fusion peptide from simian immunodeficiency virus (SIV) induces membrane fusion by promoting the formation of a non-lamellar phase, e.g., cubic (QII) phase, and inhibiting the transition to HII. Arg-Glc MRPs, at low concentration, stabilized the lamellar structure of SIV peptide containing lipid bilayers, but facilitated the formation of non-lamellar phases at medium concentration (100:5). The concentration-dependent activity of MRPs upon lipid phase transition indiciates a potential role in modulating some membrane-related biological events, e.g., viral membrane fusion.

Injectable concentrated potassium concentrate, emblematic of the lack of safety of the drug use process in French hospitals

Despite its proven dangers, the ward stock drug distribution system predominates in French hospitals. This system allows 12 million injectable ampoules of concentrated potassium chloride to circulate uncontrolled each year. Such a situation is absurd for the following reasons: 1) injected by mistake, concentrated potassium kills within seconds; 2) the true incidence of potassium-related fatalities and incidents is unknown; 3) fatal intravenous injection of potassium produces no specific anatomical changes and subtle, if any, findings at autopsy; 4) it is used for capital punishment by lethal injection in various countries; and 5) healthcare worker serial killers benefit from the fact that potassium is not identifiable in post-mortem examinations and that investigations to find the murderer are complex and of uncertain outcome. Other medications classed as high-risk have similar characteristics to those of concentrated potassium solutions. Injectable potassium can therefore be regarded as emblematic of the lack of safety of the drug use process in French hospitals. The priority measure to protect patients from this deadly risk is to remove these drugs from uncontrolled ward stocks and to provide premixed potassium solutions. Evidence of the increased safety of the unit dose drug dispensing system should compel health policy makers to systematically implement it, thus bringing the drug use process into compliance with existing French and European regulations.

Fingermarks development on gloves: Relative efficiency of 1,2 Indanedione/ZnCl2, ninhydrin and wet powder

Powder suspensions such as wet powder are used to develop fingermarks on adhesive surfaces. They can also be used on gloves but these ready-to-use commercial pre-mixed solutions are not entirely satisfactory. Among other things, they generate some background noise that can sometimes be substantial and make the exploitation of the fingermarks difficult. Recent studies have proven the effectiveness of a HFE ninhydrin solution on some types of gloves. Ninhydrin and 1,2-indanedione are reagents that are commonly used for the visualisation of fingermarks on porous and semi-porous substrates. Applying them on gloves might help to overcome the issue of background noise being produced by powder suspensions. In this study, several formulations of ninhydrin and 1,2-indanedione are compared to wet powder on a sample of nitrile, latex and vinyl gloves. The subsequent results show a greater effectiveness with the use of wet powder.

Surface rheology and morphology of beer protein and iso-humulone at air-liquid surface

Foam is one of the unique properties of beer, but how the amphiphilic components stabilize the foam is still not fully understood. This study concerns the main surface active components. For this purpose, protein from barley and iso-humulone from hop, were extracted from raw materials separately to be able to consider their effect separately and in the controlled mixture. The layers were formed in three ways, i.e. single component, pre-mixed solution and sequential addition of the individual components. Drop tensiometry and Brewster angle microscopy were employed to reveal the surface tension effects, rheological properties and morphology of the adsorbed layers.Both protein and iso-humulone showed surface activity and the combination gave synergistic effects in terms increasing the surface pressure. Surface rheology showed the combination of pre-mixed solutions of protein and iso-humulone formed the stiffest surface film. The pre-mixed solution gave higher dilatational moduli than if the two components were added sequentially. Furthermore, protein had a major influence on resisting deformation of the surface layer. The attractive interaction was confirmed by comparing the surface rheology and morphology of adsorbed layers formed by pre-mixed solutions and sequential addition. Iso-humulone also had a significant influence on interfacial properties. But this depends on whether it was pre-mixed with protein before added in to a buffer sub-phase or added to a pre-adsorbed protein layer. BAM reveals different surface morphology between the sequential addition and the pre-mixed sample. Thus, the property of the adsorbed film depends not only on the chemical composition, but also on the addition order of components.

Improved Alignment of PEDOT:PSS Induced by in-situ Crystallization of "Green" Dimethylsulfone Molecules to Enhance the Polymer Thermoelectric Performance.

Dimethylsulfone (DMSO2), a small organic molecule, was observed to induce the alignment of poly(3,4-ethylenedioxythiophene): poly(4-styrenesulfonate) (PEDOT:PSS) via in-situ crystallization in PEDOT:PSS mixture, which was verified by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and atomic force microscopy (AFM). A chemically stable dopant, DMSO2, remarkably raised the electrical conductivity of the PEDOT:PSS film, which was fabricated from pre-mixed solution of PEDOT:PSS and DMSO2, up to 1080 S/cm, and more importantly, such a PEDOT:PSS film showed a long-term humidity stability and it retained near 90% electric conductivity after 60 days, suggesting DMSO2 is promising for an eco-friendly alternative to replace dimethyl sulfoxide (DMSO), ethylene glycol (EG) and various acids dopants that have been widely employed to dope and post-treat PEDOT:PSS. Pairwise interaction energies and free energy of solvation between PEDOT:PSS and DMSO2 were calculated by first-principles and molecular mechanics, respectively, revealing the mechanism of DMSO2 in enhancing the electrical conductivity.

Investigating the Effect of Selective Oropharyngeal Decontamination Using Topical Antibiotics on Oropharyngeal and Tracheal Colonization in Trauma Patients Admitted to the Intensive Care Units of Zahedan, Iran: A Clinical Trial Study

Background: Pneumonia is one of the most common hospital-acquired infections, where 86% is associated with mechanical ventilation, known as ventilator- associated pneumonia (VAP). Oropharyngeal decontamination reduces the incidence of VAP by medicinal agents. Objectives: The aim of the present study was to determine the effect of oropharyngeal decontamination using topical antibiotics on oropharyngeal and tracheal colonization of trauma patients admitted to the intensive care unit (ICU). Methods: The present double-blind clinical trial was performed on trauma patients, who underwent endotracheal intubation during the first 24 hours, at the ICU of Khatam-al-Anbia Hospital, Zahedan, during years 2017 to 2018. The sample size was 100 individuals, who were selected using the convenience sampling method and randomly assigned to intervention and control groups. The study began with the start of intubation and lasted for five days. When oral and tracheal culture samples were sent to the laboratory during the first 24 hours after endotracheal intubation, the pre-mixed solution of nystatin, polymyxin B, and neomycin was rubbed to the mouth, lips, gingiva, and cheeks of the intervention group, using syringes and gloves, four times a day. The tracheal and oral secretions were cultured in the intervention and control groups at the beginning and the end of the study. Data analysis was carried out using the SPSS version 21 software. Independent t test and paired t test were used to compare the quantitative variables, and qualitative variables were compared using the chi-square test and Fisher's exact test. The significance level was considered at 0.05. Results: When the final drop-out occurred, out of 44 remaining patients in the intervention group, the number of negative oral cultures increased from 31 cases (70.5%) in the pretest to 39 (88.6%) in the posttest. A total of 25 negative oral cultures were recorded in the control group in both the pretest and posttest stages. Also, the number of negative tracheal cultures in the intervention group increased from 38 cases (86.4%), in the first turn, to 44 (100%) cases in the second turn; while in the control group, the number of negative tracheal cultures was recorded as 39 (88.6%) in the first turn and increased to 40 cases (100%) in the second turn. Conclusions: Clinically, reduced colonization rate of invasive bacteria, as the main result of the present study, indicates a decrease in the incidence of inappropriate alterations in oral microbial flora that can subsequently be effective in reducing the incidence of diseases, such as pneumonia.

Surface modification and stabilisation of kaolin part 1: effects of CTAC-PP fibre composites

ABSTRACTThis paper presents an experimental study of the effects of surface modification and fibre types on the stabilisation of kaolin slurry. A pre-mixed solution of cationic surfactant – cetyltrimethylammonium chloride (CTAC), selected after preliminary screening based on the knowledge of the substrate, have been used for the surface modification of kaolin prior to stabilisation with different types of synthetic polypropylene (PP) fibres. The results show an improvement in the shearing resistance of kaolin when stabilised with different types, proportions, and lengths of fibres. At higher fibre content, there is an increase in the shearing resistance of the fibre-stabilised kaolin composites for the three categories of fibres tested. Furthermore, the shearing resistance of the CTAC-PP fibre composites converges as the confining stress increases from 160kPa to 480kPa. In general, the shearing resistance of surface modified kaolin stabilised with 5% fibre length is slightly higher than corresponding composites containing unmodified kaolin.

Large eddy simulation/dynamic thickened flame modeling of a high Karlovitz number turbulent premixed jet flame

Due to the complex multiscale interaction between intense turbulence and relatively weak flames, turbulent premixed flames in the thin and broken reaction zones regimes exhibit strong finite-rate chemistry and strain effects and are hence challenging to model. In this work, a laboratory premixed jet flame in the broken reaction zone, which has recently been studied using direct numerical simulation (DNS), is modeled using a large eddy simulation (LES)/dynamic thickened flame (DTF) approach with detailed chemistry. The presence of substantial flame thickening due to strong turbulence-chemistry interactions, which can be characterized by a high Karlovitz number (Ka), requires the DTF model to thicken the flame in an adaptive way based on the local resolution of flame scales. Here, an appropriate flame sensor and strain-sensitive flame thickness are used to automatically determine the thickening location and thickening factor, respectively. To account for finite-rate chemistry and strain effects, the chemistry is described in two different ways: (1) detailed chemistry denoted as full transport and chemistry (FTC), and (2) tabulated chemistry based on a strained premixed flamelet (SPF) model. The performance of the augmented LES/DTF approach for modeling the high Ka premixed flame is assessed through detailed a posteriori comparisons with DNS of the same flame. It is found that the LES/DTF/FTC model is capable of reproducing most features of the high Ka turbulent premixed flame including accurate CO and NO prediction. The LES/DTF/SPF model has the potential to capture the impact of strong turbulence on the flame structure and provides reasonable prediction of pollutant emissions at a reasonable computational cost. In order to identify the impact of aerodynamic strain, the turbulent flame structure is analyzed and compared with unstrained and strained premixed flamelet solutions. The results indicate that detailed strain effects should be considered when using tabulated methods to model high Ka premixed flames.

Comparative analysis of methods for heat losses in turbulent premixed flames using physically-derived reduced-order manifolds

Heat losses have the potential to substantially modify turbulent combustion processes, especially the formation of pollutants such as nitrogen oxides. The chemistry governing these species is strongly temperature sensitive, making heat losses critical for an accurate prediction. To account for the effects of heat loss in large eddy simulation (LES) using a precomputed reduced-order manifold approach, thermochemical states must be precomputed not only for adiabatic conditions but also over a range of reduced enthalpy states. However, there are a number of methods for producing reduced enthalpy states, which invoke different implicit assumptions. In this work, a set of a priori and a posteriori LES studies have been performed for turbulent premixed flames considering heat losses within a precomputed reduced-order manifold approach to determine the sensitivity to the method by which reduced enthalpy states are generated. Two general approaches are explored for generating these reduced enthalpy states and are compared in detail to assess any effects on turbulent flame structure and emissions. In the first approach, the enthalpy is reduced at the boundary of the one-dimensional (1D) premixed flame solution, resulting in a single enthalpy deficit for a single premixed flame solution. In the second approach, a variable heat loss source term is introduced into the 1D flame solutions by mimicking a real heat loss to reduce the post-flame enthalpy. The two approaches are compared in methane–air piloted turbulent premixed planar jet flames with different diluents that maintain a constant adiabatic flame temperature but experience different radiation heat losses. Both a priori and a posteriori results, as well as a chemical pathway analysis, indicate that the manner by which the heat loss is accounted for in the manifold is of secondary importance compared to other model uncertainties such as the chemical mechanism, except in situations where heat loss is unphysically fast compared to the flame time scale. A new theoretical framework to explain this insensitivity is also proposed, and its validity is briefly assessed.

Elucidating the mechanisms behind thermoelectric power factor enhancement of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) flexible films

Conducting polymers that have shown their potential in flexible electronics and sensorics for the last one decade can be looked upon as promising materials for room temperature thermoelectric applications. Among all the existing popular conducting polymers, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is being widely studied because of its extraordinary high electrical conductivity and environmental stability. This article explains the possible mechanisms behind power factor enhancement of solvent-mixed flexible PEDOT:PSS films. The films drop-casted on polyimide sheets by using both pristine and organic solvent (dimethyl sulphoxide i.e. DMSO) pre-mixed solutions were optimized for both annealing temperature and solvent concentrations. The detailed characterization of these films suggested that PSS was detached from PEDOT:PSS after DMSO addition. Selective eviction of PSS from typical core-shell structure of PEDOT:PSS not only caused conformational change in PEDOT chains from benzoid (coiled structure) to quinoid (linear structure) but also re-arranged PSS in more stretched form. Such a modification of the chemical structure caused improvement in power factor mainly due to enhanced charge carriers' mobility rather than increased doping/carrier concentration. A flexible thermoelectric generator consisting of an array of thirty elements was also fabricated by drop-casting DMSO-mixed PEDOT:PSS solution through a patterned mask. This array resulted in an output voltage of ∼17.6 mV under a temperature gradient of 80 °C.

Management of Diarrhoeal Dehydration in Childhood: A Review for Clinicians in Developing Countries.

The survival of a child with severe volume depletion at the emergency department depends on the competency of the first responder to recognize and promptly treat hypovolemic shock. Although the basic principles on fluid and electrolytes therapy have been investigated for decades, the topic remains a challenge, as consensus on clinical management protocol is difficult to reach, and more adverse events are reported from fluid administration than for any other drug. While the old principles proposed by Holliday and Segar, and Finberg have stood the test of time, recent systematic reviews and meta-analyses have highlighted the risk of hyponatraemia, and hyponatraemic encephalopathy in some children treated with hypotonic fluids. In the midst of conflicting literature on fluid and electrolytes therapy, it would appear that isotonic fluids are best suitable for the correction of hypotonic, isonatraemic, and hypernatraemic dehydration. Although oral rehydration therapy is adequate to correct mild to moderate isonatraemic dehydration, parenteral fluid therapy is safer for the child with severe dehydration and those with changes in serum sodium. The article reviews the pathophysiology of water and sodium metabolism and, it uses the clinical case examples to illustrate the bed-side approach to the management of three different types of dehydration using a pre-mixed isotonic fluid solution (with 20 or 40 mmol/L of potassium chloride added depending on the absence or presence of hypokalemia, respectively). When 3% sodium chloride is unavailable to treat hyponatraemic encephalopathy, 0.9% sodium chloride becomes inevitable, albeit, a closer monitoring of serum sodium is required. The importance of a keen and regular clinical and laboratory monitoring of a child being rehydrated is emphasized. The article would be valuable to clinicians in less-developed countries, who must use pre-mixed fluids, and who often cannot get some suitable rehydrating solutions.

Fabrication and properties of porous Si3N4 ceramics by aqueous gelcasting using low-toxic DMAA gelling agent

A low-toxic and water-soluble monomer N, N-dimethylacrylamide (DMAA) was employed as a gelling agent in the gelcasting of porous Si3N4 ceramics. The process conditions and composition for slurry preparation (with a solid loading of 36 vol%), the consolidation and sintering of green bodies were investigated and optimized. The effects of various factors such as zeta potential, pH value of the premix solution, dispersant dosage and ball milling time on the rheological properties of the slurries were investigated. The results suggest that the best rheological properties (66.5 mPa.s at a shear rate of 96.3 s−1) of the slurries were obtained when pH value ranged between 9 and 11, dispersant dosage reached 1 wt%, and ball milling time was 6 h. All the as-prepared green bodies showed a homogeneous microstructure and high flexural strength ≥ 26 MPa with a maximum up to 46.3 MPa when the ratio of DMAA to MBAM, initiator dosage, polymerization temperature and time were 14, 1 wt%, 70 °C and 90 min, respectively. The sintered bodies had a homogeneous microstructure, excellent and regulatable properties, a flexural strength of 216.3–327.3 MPa, and a porosity of 39.6–29.1% by varying the sintering temperature from 1710 °C to 1810 °C and the holding time from 1 h to 3 h. The superior comprehensive effect makes DMAA a promising candidate for an environmentally friendly gelling agent in gelcasting of porous Si3N4 ceramics.

Centrifugation-Controlled Thermal Convection and Its Application to Rapid Microfluidic Polymerase Chain Reaction Devices

Here, we report the developed cyclo olefin polymer (COP) microfluidic chip on a fabricated rotating heater stage that utilizes centrifugation-assisted thermal cycle in a ring-structured microchannel for polymerase chain reaction (PCR). The PCR solution could be driven by thermal convection and continuously exchanged high/low temperatures in a ring structured microchannel without the use of typical syringe pump. More importantly, the flow rate was controlled by the relative gravitational acceleration only. The platform enables amplification within 10 min at 5G and has a detection limit of 70.5 pg/channel DNA concentration (β-actin, 295 bp). The current rotating system is capable of testing four different samples in parallel. The microfluidic chip can be preloaded with the PCR premix solution for on-site utility, and, with all of the features integrated to the system, the test can be conducted without the need for specialized laboratory and trained laboratory staff. In addition, this innovative chemical reaction technique has the potential to be utilized in other micromixing applications.