Gamma-butyrolactone Research Articles

Injector port acylation of γ-hydroxybutyrate (GHB): Condition optimisation, source adjustments, and characterisation of the derivatives

For several years, gas chromatography-mass spectrometry (GC–MS) has been used to identify gamma-hydroxybutyrate (GHB) in forensic toxicology cases. However, under injector port conditions GHB can dehydrate into gamma-butyrolactone (GBL). Therefore, it is important for GHB to undergo a derivatisation reaction before an analysis to avoid the production of GBL; various analytical methods have been developed for the analysis of GHB but very few methods use acylation as a form of derivatisation. This study explores the optimisation of injector port acylation of GHB to improve its detectability and thermostability. By utilising trifluoroacetic acid anhydride (TFAA) and heptafluorobutyric acid anhydride (HFBA) to enhance the chromatography and mass spectra of the resulting derivatives. As a result, both reagents improved the detectability of GHB, with TFAA producing more predominant peaks within the chromatogram and HFBA offering a more complex mass spectrum. The optimal injector temperature was found to be 240 °C for both reagents, which significantly increased the derivatisation yields. These results demonstrate the effectiveness of injector port acylation as an alternative derivatisation route for GHB related drug cases.

Superwettable microchip for visual detection of date-rape drug in beverages

Gamma-hydroxybutyric acid (GHB), which is used in drug-facilitated sexual assault, is typically delivered in the form of gamma-butyrolactone (GBL) in beverage carriers. In response to the growing need of methods for rapid and on-site sensing of the drugs, we carried out an investigation aimed at developing a superwettable microchip for visual detection of the date-rape drug GBL in adulterated beverages. The superwettable microchip is comprised of Fe3O4 nanoparticles which aggregate to form a reactive spot on a superhydrophobic fabric. The spot captures and confines microdroplets containing GBL on the superhydrophobic substrate. Fe(III), generated by HCl promoted reaction of the Fe3O4 spot, then participates in a colorimetric reaction with GBL to form a naked eye observable colored complex. Quantitative determination of GBL in beverages is achieved by analyzing the red proportion of a smartphone camera derived image. The detection range of this assay protocol is ca. 0.1–10 mg mL−1, which meets the requirements to detect potentially dangerous concentration of GBL in drinks. The detection stability of the superwettable microchip for GBL in water and common beverages is maintained over at least 30 cycles.

Optogenetic stimulation of dorsal striatum bidirectionally controls seizures.

Engagement of the striatum (caudate/putamen) and other basal ganglia nuclei during seizures was first observed over 75 years ago. Basal ganglia output nuclei, and the substantia nigra pars reticulata, in particular, have well-established anti-seizure effects across a large array of experimental models. However, striatal control of seizures is understudied. To address this gap, we used optogenetic approaches to activate and inactivate neurons in the dorsal striatum of Sprague-Dawley rats submitted to the gamma-butyrolactone (GBL) model of absence epilepsy, amygdala kindling model of temporal lobe epilepsy, and pilocarpine-induced Status Epilepticus (SE). All tests were performed on a within-subject basis. Animals were tested in two different light frequencies (5 Hz and 100 Hz). Open-loop (continuous light delivery) optogenetic activation of the dorsal striatal neurons robustly suppressed seizures in all models. On the other hand, optogenetic silencing of the dorsal striatal neurons increased absence seizure expression and facilitated SE onset but had no effect on kindled limbic seizures. In the GBL model, we also verified if the closed- loop strategy (light delivery in response to seizure detection) would be enough to induce antiseizure effects. On-demand light delivery in ChR2-expressing animals reduced SWD duration, while the same approach in ArchT-expressing animals increased SWD duration. These results demonstrated previously unrecognized anti-absence effects associated with striatal continuous and on-demand neuromodulation. Together, these findings document a robust, bidirectional role of the dorsal striatum in the control of seizure generation and propagation in a variety of seizure models, including focal seizure onset and generalized seizures.

Temporal and Potential Predictive Relationships between Sleep Spindle Density and Spike-and-Wave Discharges.

Spike-and-wave discharges (SWDs) and sleep spindles are characteristic electroencephalographic (EEG) hallmarks of absence seizures and nonrapid eye movement sleep, respectively. They are commonly generated by the cortico-thalamo-cortical network including the thalamic reticular nucleus (TRN). It has been reported that SWD development is accompanied by a decrease in sleep spindle density in absence seizure patients and animal models. However, whether the decrease in sleep spindle density precedes, coincides with, or follows, the SWD development remains unknown. To clarify this, we exploited Pvalb-tetracycline transactivator (tTA)::tetO-ArchT (PV-ArchT) double-transgenic mouse, which can induce an absence seizure phenotype in a time-controllable manner by expressing ArchT in PV neurons of the TRN. In these mice, EEG recordings demonstrated that a decrease in sleep spindle density occurred 1 week before the onset of typical SWDs, with the expression of ArchT. To confirm such temporal relationship observed in these genetic model mice, we used a gamma-butyrolactone (GBL) pharmacological model of SWDs. Prior to GBL administration, we administered caffeine to wild-type mice for 3 consecutive days to induce a decrease in sleep spindle density. We then administered low-dose GBL, which cannot induce SWDs in normally conditioned mice but led to the occurrence of SWDs in caffeine-conditioned mice. These findings indicate a temporal relationship in which the decrease in sleep spindle density consistently precedes SWD development. Furthermore, the decrease in sleep spindle activity may have a role in facilitating the development of SWDs. Our findings suggest that sleep spindle reductions could serve as early indicators of seizure susceptibility.

Architecture of bimodal porous CuO/Al2O3-controlled continuous and low-temperature production of biomass-derived γ-butyrolactone

Biomedical activities of gamma butyrolactone (GBL) play an important role in the development of novel physiological and therapeutic agents. Maleic anhydride catalytic liquid phase hydrogenation allows for selective synthesis of GBL. However, this process is hampered by high cost noble metals and high reaction pressure conditions. Here, we demonstrate cyclic dehydrogenation of biomass-derived 1,4-butanediol (1,4-BDO) under atmospheric pressure and low-temperature conditions using highly dispersed and chemically stabilized Cu species on bimodal porous Al2O3. The bimodal porous Al2O3 exhibited both Lewis and Brønsted acidic properties along with high specific surface area and large pore volume. Among prepared catalysts, 15 wt% Cu/Al2O3 catalyst has shown an optimal crystallite size, bimodal porous nature, and high diffusion properties. Hence, high catalytic activity and remarkable GBL yields with very high 1,4-BDO conversion for 50 h of continuous time-on-stream. The unique bimodal textural properties help to enhance the dehydrogenation activity with a high turnover frequency (TOF) of about 5.0118 x 10-3 s-1via efficient chemical interaction between metallic Cu and 1,4-BDO molecules.

One-Pot Electrosynthesis of Gamma-Butyrolactone (GBL) from Biomass-Derived Furoic Acid

An efficient catalytic method to transform biomass into value-added products is critical to promoting a sustainable future. Ideally, such a transformation should be carried out efficiently in mild conditions. Herein, we developed a mild one-pot electrochemical protocol for converting furoic acid (FA), a common biomass-derived feedstock, into a versatile platform chemical, gamma-butyrolactone (GBL). All involved species participate in the desired redox pathway with high selectivity: FA was electrochemically oxidized with 84.2% selectivity to 2(5H)-furanone, the olefin of which was then hydrogenated to yield GBL with 98.5% selectivity. We identified that a specific temperature is an essential factor in enabling the one-pot reaction as it promotes thermal desorption of the key intermediate. The reaction was scalable to gram-scale, producing high-purity GBL isolated through a simple solvent extraction from a 500-mL electrolysis scale reaction.

One-Pot Electrosynthesis of Gamma-Butyrolactone (GBL) from Furoic Acid

The catalytic valorization of biomass to afford synthetically useful small molecules is essential for sustainable biorefinery processes. Herein, we present a mild cascaded electrochemical protocol for converting furoic acid (FA), a common biomass-derived feedstock, into a versatile platform chemical, gamma-butyrolactone (GBL). All involved species participate in the desired redox pathway with high selectivity: FA was electrochemically oxidized with 84.2% selectivity to 2(5H)-furanone (2-FO), the olefin of which was then hydrogenated to yield GBL with 98.5% selectivity. We identified that a certain temperature is an important factor in enabling the one-pot reaction as it promotes thermal desorption of the key intermediate. The reaction was scalable to gram-scale, producing high-purity GBL isolated through a simple solvent extraction from a 500-mL electrolysis scale reaction.

Fabricating Planar Perovskite Solar Cells through a Greener Approach.

High-quality perovskite thin films are typically produced via solvent engineering, which results in efficient perovskite solar cells (PSCs). Nevertheless, the use of hazardous solvents like precursor solvents (N-Methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), dimethylformamide (DMF), gamma-butyrolactone (GBL)) and antisolvents (chlorobenzene (CB), dibutyl ether (DEE), diethyl ether (Et2O), etc.) is crucial to the preparation of perovskite solutions and the control of perovskite thin film crystallization. The consumption of hazardous solvents poses an imminent threat to both the health of manufacturers and the environment. Consequently, before PSCs are commercialized, the current concerns about the toxicity of solvents must be addressed. In this study, we fabricated highly efficient planar PSCs using a novel, environmentally friendly method. Initially, we employed a greener solvent engineering approach that substituted the hazardous precursor solvents with an environmentally friendly solvent called triethyl phosphate (TEP). In the following stage, we fabricated perovskite thin films without the use of an antisolvent by employing a two-step procedure. Of all the greener techniques used to fabricate PSCs, the FTO/SnO2/MAFAPbI3/spiro-OMeTAD planar device configuration yielded the highest PCE of 20.98%. Therefore, this work addresses the toxicity of the solvents used in the perovskite film fabrication procedure and provides a promising universal method for producing PSCs with high efficiency. The aforementioned environmentally friendly approach might allow for PSC fabrication on an industrial scale in the future under sustainable conditions.

Structure, dynamic, and free energy analyses of 5-hydroxymethylfurfural in aprotic solvents and imidazolium ionic liquids using all-atom molecular dynamics simulations.

5-Hydroxymethylfurfural (5-HMF) is an important chemical generated from lignocellulosic biomass (LCB) to produce a wide variety of value-added chemicals, biofuels, and biochemicals. Different forms of ionic liquids (ILs) have been utilized for the formation of 5-HMF from LCB. However, 5-HMF is highly soluble in imidazolium-based ionic liquids (IMILs), which makes it difficult to separate after its formation from LCB. In this manuscript, we perform all-atom molecular dynamics simulations to investigate the performance of several aprotic solvents in the extraction of 5-HMF from various IMILs. We consider twelve aprotic solvents with different physicochemical properties, such as acetonitrile (AN), acetone (AT), 1,4-dioxane (DI), N,N-dimethyl acetamide (DMA), N,N-dimethyl formamide (DMF), dimethyl sulfoxide (DMSO), gamma-butyrolactone (GBL), gamma-valerolactone (GVL), hexamethylphosphoramide (HMPA), N-methyl pyrrolidone (NMP), propylene carbonate (PC), and sulfolane (SF). We analyze various structures and dynamics and perform a detailed thermodynamic analysis to understand the underlying molecular behavior. The results indicate that solvents AT and DI showed the least favorable interactions with 5-HMF, whereas HMPA showed the most favorable interactions with 5-HMF. Based on the detailed structural insights, HMPA enhances the separation of 5-HMF from the ILs. Furthermore, different anion combinations were tested to benchmark their separation capability. Overall, the results presented in this manuscript guide the selection of solvent and IL combinations for the effective separation of 5-HMF.

Synergistic Cation Solvation Reorganization and Fluorinated Interphase for High Reversibility and Utilization of Zinc Metal Anode.

Batteries based on zinc (Zn) chemistry offer a great opportunity for large-scale applications owing to their safety, cost-effectiveness, and environmental friendliness. However, the poor Zn reversibility and inhomogeneous electrodeposition have greatly impeded their practical implementation, stemming from water-related passivation/corrosion. Here, we present a multifunctional electrolyte comprising gamma-butyrolactone (GBL) and Zn(BF4)2·xH2O to resolve these intrinsic challenges. The systematic results confirm that water reactivity toward a Zn anode is minimized by forcing GBL solvents into the Zn2+ solvation shell and constructing a fluorinated interphase on the Zn anode surface via anion decomposition. Furthermore, NMR was selected as an auxiliary testing protocol to elevate and understand the role of electrolyte composition in building the interphase. The combined factors in synergy guarantee high Zn reversibility (average Coulombic efficiency is 99.74%), high areal capacity (55 mAh/cm2), and high Zn utilization (∼91%). Ultimately, these merits enable the Zn battery utilizing a VO2 cathode to operate smoothly over 5000 cycles with a low-capacity decay rate of ∼0.0083% per cycle and a 0.23 Ah VO2/Zn pouch cell to operate over 400 cycles with a capacity retention of 77.3%.

Reversible Fe3+-induced urushi organogels in gamma butyrolactone

A multinetwork structured urushi organogel was created using low-volatility gamma butyrolactone (GBL) solvent and Fe3+ ions. The urushi organogels were fabricated through chemical crosslinking with the oxidative polymerization of urushiol as well as physical crosslinking due to the coordination bonds with Fe3+ ions in the Fe3+/urushiol/GBL solution. The role of Fe3+ ions is to provide physical crosslinking sites via the coordination bond with the catechol functional moiety of urushiol and also to serve as the catalysts for the polymerization of urushiol. The gelation and characteristics of urushi organogels in GBL with different amounts of Fe3+ ions were investigated. The formation of urushi organogel by chemical crosslinking and physical coordination crosslinking was investigated by FT-IR, Raman spectroscopy and X-ray photoelectron spectroscopy.The presence of a physical coordination bond between the Fe3+ ion and the catechol moiety of urushiol provides reversible adhesive properties, which provide consistent tensile strength after reattaching the urushi organogel film. The stretchability as well as the reversibility in mechanical strength can provide the possibility for various applications of eco-friendly natural urushi. This research provides not only a method to prepare multinetwork natural urushi organogels using Fe3+ ions but also the great possibility of expanding the application area of natural urushi(ol)s.

Synthesis and characterization of mehtylammonium bismuth iodide via solvent engineering

Hybrid organic–inorganic halide perovskites (OIHPs) are an emerging class of photovoltaic materials that have gained tremendous attention in the field of optoelectronics. This work aims to investigate the characteristics of bismuth-based halide perovskite via solvent engineering for solar cell application. A bismuth-based organo-inorganic perovskite was synthesized and characterized for solar cell application via solvent engineering using Gamma Butyrolactone (GBL) as the based solvent and enhanced with Methylamine (MA) and acetonitrile (ACN). A solution processing facile method was adopted in the synthesis of the perovskite. The solvent engineering aims to tune its band gap and a remarkable band gap of 1.58eV which is within the range of an ideal band gap (1.5-1.6) required for solar cell application. The XRD micrograph exhibited several narrow sharp peaks which indicated crystallinity formation of the synthesized sample with 86% crystallinity. The FESEM/EDS micrograph indicated nature of the formed crystals and the chemical composition of the sample. A multilayer heptagonal crystal was observed. The TGA result showed that the sample is thermally stable at a temperature of 200oC before degradation occurred.

Hydrogel-based heterogeneous-acid-catalysts for converting carbohydrates into the platform chemical: 5-hydroxymethylfurfural

Background5-hydroxymethylfurfural (5-HMF) is a significant platform chemical with the potential to be converted into hydrocarbon biofuels. Herein, a facile and reusable catalyst was investigated to synthesize 5-HMF from monosaccharides in a green solvent medium following eight green chemistry principles. MethodsA hydrogel-based heterogeneous acid catalyst was synthesized through photoreaction to determine its ability to dehydrate fructose in the invert sugar syrup into 5-HMF. The main structure of the hydrogel catalyst was formed with polyethylene glycol diacrylate (PEGDA), and this backbone structure was modified by 3-sulfopropyl methacrylate potassium salt (3SMP) and further acidified by 3M HCl to form PEGDA-3SMP-H with 32.54 mmole/g of H+ amount on the catalyst. Significant findingsWith the PEGDA-3SMP-H catalyst, fructose conversion of 85.80% with a 5-HMF yield of 46.99% could be attained at 120°C for a 24 h reaction time in an aqueous medium with the co-solvent gamma-butyrolactone (GBL), which is considered a green solvent medium. PEGDA-3SMP-M (M=metal) hydrogel catalyst was synthesized using 8 different metal ions fixed on the 3SMP through ion exchange. The catalytic ability sequence for synthesized hydrogel catalysts followed H+> Cr3+> Cu2+> Al3+> Ni2+> Co2+ > Cu+> Fe3+> Fe2+ for 5-HMF formation. The 5-HMF yield was improved with consecutive cycles of using a regenerated PEGDA-3SMP-H catalyst. In the first cycle, the 5-HMF yield was 36.86%; in the second and third cycles, it was 39.39% and 41.49%, respectively. The prepared heterogeneous catalyst is preferred in terms of industrial applications owing to its facile synthesis, recyclability, stability, simple separation method, low equipment corrosion, and minimization of final product contamination with acid catalysts.

All green sulfolane-based solvent enhanced electrical conductivity and rigidity of perovskite crystalline layer

Industrial commercialization of perovskite solar cells not only depends on sufficient device performance, but also requires complete elimination of hazardous solvents in the fabrication process to enable sustainable development of the technology. This work reports a new solvent system based on sulfolane, gamma-butyrolactone (GBL), and acetic acid (AcOH) as a significantly greener alternative to common but more hazardous solvents. Interestingly, this solvent system not only resulted in densely-packed perovskite layer of bigger crystal size and better crystallinity, the grain boundaries were found to be more rigid and highly conductive to electrical current. The physical changes at the grain boundaries were due to the sulfolane-infused crystal interfaces, which were expected to facilitate better charge transfer and provide stronger barrier to moisture within the perovskite layer, yielding higher current density and longer performance of the device as a result. In fact, by using a mixed solvent system consisting of sulfolane, GBL, and AcOH in the volume ratio of 70.0:27.5:2.5, the device stability was better and the photovoltaic performance was statistically comparable with those prepared using DMSO-based solvent. Our report reflects unprecedented findings of enhanced electrical conductivity and rigidity of the perovskite layer simply by using an appropriate choice of the all-green solvent.

Selective Oxidation of Tetrahydrofuran to Gamma-Butyrolactone over Spinel ZnFe2O4 Nanoparticle Catalyst

The selective oxidation of tetrahydrofuran (THF) to gamma-butyrolactone (GBL) on spinel ZnFe2O4 nanoparticles (ZFNPs) was investigated. The catalyst was prepared with the coprecipitation method and characterized by FTIR, XRD, TEM, SEM, EDS, TGA, XPS, and BET surface area. The characterization techniques showed that a nonuniform spherical spinal oxide with an average particle size of 26 nm was formed. The oxidation reaction was carried out using hydrogen peroxide as an oxidizing agent under solvent-free conditions. GC-MS analysis revealed that the main product was GBL. 2-hydroxytetrahydrofuran (THF-2-OH), gamma-hydroxybutyric acid (GHBA), and gamma-hydroxybutaldehyde (GHBAl) were obtained as minor products. The effects of different reaction parameters, such as temperature, H2O2/THF mole ratio, catalyst dose, reaction time, and reusability, were evaluated. A 47.3% conversion of THF with an 88.2% selectivity of GBL was achieved by conducting the reaction at 80 °C for nine hours using a 1:1 mole ratio of H2O2/THF. A slight increase in the conversion degree was attained at higher temperatures; however, an over-oxidation process was observed as the temperature exceeded 80 °C. The catalyst remained effective and stable over four reuses.

Insight to the Local Structure of Mixtures of Imidazolium-Based Ionic Liquids and Molecular Solvents from Molecular Dynamics Simulations and Voronoi Analysis.

While the physicochemical properties as well as the NMR and vibration spectroscopic data of the mixtures of ionic liquids (ILs) with molecular solvents undergo a drastic change around the IL mole fraction of 0.2, the local structure of the mixtures pertaining to this behavior remains unclear. In this work, the local structure of 12 mixtures of 1-butyl-3-methylimidazolium cation (C4mim+) combined with perfluorinated anions, such as tetrafluoroborate (BF4-), hexafluorophosphate (PF6-), trifluoromethylsulfonate (TFO-), and bis(trifluoromethanesulfonyl)imide, (TFSI-), and aprotic dipolar solvents, such as acetonitrile (AN), propylene carbonate (PC), and gamma butyrolactone (γ-BL) is studied by molecular dynamics simulations in the entire composition range, with an emphasis on the IL mole fractions around 0.2. Distributions of metric properties corresponding to the Voronoi polyhedra of the particles (volume assigned to the particles, local density, radius of spherical voids) are determined, using representative sites of the cations, anions, and the solvent molecules, to characterize the changes in the local structure of these mixtures. By analyzing the mole fraction dependence of the average value, fluctuation, and skewness parameter of these distributions, the present study reveals that, around the IL mole fraction of 0.2, the local structure of the mixture undergoes a transition between that determined by the interionic interactions and that determined by the interactions between the ions and solvent molecules. It should be noted that the strength of the interactions between the ions and the solvent molecules, modulated by the change in the composition of the mixture, plays an important role in the occurrence of this transition. The signature of the change in the local structure is traced back to the nonlinear change of the mean values, fluctuations, and skewness values of the metric Voronoi polyhedra distributions.

Paroxysmal slow-wave discharges in a model of absence seizure are coupled to gamma oscillations in the thalamocortical and limbic systems

ObjectiveUsing the gamma-butyrolactone (GBL) model of absence seizures in Long-Evans rats, this study investigated if gamma (30–160 Hz) activity were cross-frequency modulated by the 2–6 Hz slow-wave discharges induced by GBL in the limbic system. We hypothesized that inactivation of the nucleus reuniens (RE), which projects to frontal cortex (FC) and hippocampus, would affect the cross-frequency coupling of gamma (γ) in different brain regions. MethodsLocal field potentials were recorded by electrodes implanted in the FC, ventrolateral thalamus (TH), basolateral amygdala (BLA), nucleus accumbens (NAC), and dorsal hippocampus (CA1) of behaving rats. At each electrode, the coupling between the γ amplitude envelope to the phase of the 2–6 Hz slow-waves (SW) was measured by modulation index (MI) or cross-frequency coherence (CFC) of γ amplitude with SW. In separate experiments, the RE was infused with saline or GABAA receptor agonist, muscimol, before the injection of GBL. ResultsFollowing GBL injection, an increase in MI and CFC of SW to γ1 (30–58 Hz), γ2 (62–100 Hz) and γ3 (100–160 Hz) bands was observed at the FC, hippocampus and BLA, with significant increase in SW-γ1 and SW-γ3 coupling at TH, and increase in peak SW-γ1 CFC at NAC. Strong SW-γ modulation was also found during baseline immobility high-voltage spindles. Muscimol inactivation of RE, as compared to saline infusion, significantly decreased SW-γ1 CFC in the FC, and peak frequency of the SW-γ1 CFC in the thalamus, but did not significantly alter SW-γ CFCs in the hippocampus, BLA or NAC. SignificanceThe paroxysmal 2–6 Hz SW discharges, a hallmark of absence seizure, significantly modulate γ activity in the hippocampus, BLA and NAC, suggesting a modulation of limbic functions. RE inactivation disrupted the SW modulation of FC and TH, partly supporting our hypothesis that RE participates in the modulation of SW discharges.

Lethal Lust: Suicidal Behavior and Chemsex—A Narrative Review of the Literature

Chemsex is described as the use of certain drugs-commonly methamphetamine, gamma-butyrolactone (GBL)/gammahydroxybutyrate (GHB), and mephedrone-before or during planned sexual activity primarily among men who have sex with men (MSM). Evidence shows that MSM who engage in chemsex are at increased risk of physical harm, such as sexually transmittable infections (STIs), and are more likely to experience mental health symptoms. To further assess this, we reviewed the recent literature to evaluate whether the psychological impact of chemsex behavior includes suicidal ideation and suicidal attempts. Pubmed/MEDLINE was searched for articles reporting suicidal ideation and behavior among chemsex users with the terms "chemsex", "sexualized drug use", "suicide", and "mental health". Twelve articles (three case reports and nine cross-sectional studies) were included in the final narrative review. Overall, we retrieved mixed results regarding the relationship between chemsex practice and suicidality outcomes. Considering the inhomogeneous nature of the studies, the findings indicate that suicidality could be an issue of concern among MSM in general but among chemsex users in particular. Possible risk factors for suicidality among chemsex participants may include adversities experienced due to one's sexual orientation and an increased risk for HIV and other STI infections and the resulting negative impact on mental well-being. These aspects warrant further investigations.

Use of Nucleating Agent NA11 in the Preparation of Polyvinylidene Fluoride Dual-Layer Hollow Fiber Membranes.

Polyvinylidene fluoride (PVDF) dual-layer hollow fiber membranes were simultaneously fabricated by thermally induced phase separation (TIPS) and non-solvent induced phase separation (NIPS) methods using a triple orifice spinneret (TOS) for water treatment application. The support layer was prepared from a TIPS dope solution, which was composed of PVDF, gamma-butyrolactone (GBL), and N-methyl-2-pyrrolidone (NMP). The coating layer was prepared from a NIPS dope solution, which was composed of PVDF, N,N-dimethylacetamide (DMAc), and polyvinylpyrrolidone (PVP). In order to improve the mechanical strength of the dual-layer hollow fiber, a nucleating agent, sodium 2,2'-methylene bis-(4,6-di-tert-butylphenyl) phosphate (NA11), was added to the TIPS dope solution. The performance of the membrane was evaluated by surface and cross-sectional morphology, water flux, mechanical strength, and thermal property. Our results demonstrate that NA11 improved the mechanical strength of the PVDF dual-layer hollow fiber membranes by up to 42%. In addition, the thickness of the coating layer affected the porosity of the membrane and mechanical performance to have high durability in enduring harsh processing conditions.

The use of chlordiazepoxide for outpatient gamma-butyrolactone (GBL) detoxification: An observational study

Background Various detoxification regimens are used for gamma-hydroxybutyrate (GHB) and gamma-butyrolactone (GBL), including diazepam, barbiturates, baclofen and GHB itself. However, these regimens are primarily derived from inpatient units, and literature on outpatient GBL detoxification is sparse with no previous reports on chlordiazepoxide. We describe the characteristics of outpatient GBL detoxification using chlordiazepoxide. Methods Observational study of all patients who attended a community outpatient addiction service in South London between August 2015 and November 2017 seeking detoxification from GBL. The outpatient caseload is predominantly patients with alcohol, opioid and stimulant dependence. Routine clinical data including patient demographics, GBL usage, daily chlordiazepoxide dose and Clinical Institute Withdrawal Assessment for Alcohol-revised (CIWA-Ar) score were recorded. Results In the study period there were 17 attendances for GBL detoxification, 14 of which were undertaken in the outpatient setting. Twelve (86%) patients who had an outpatient detoxification were male, all of whom were men who have sex with men. Of 14 outpatient GBL detoxifications managed with chlordiazepoxide, 10 were successfully completed. One of the four patients that did not complete detoxification required inpatient treatment in an acute hospital. The average successful detoxification took 10 ± 3.1 days. For patients who completed a detoxification, the median maximum CIWA-Ar score on day one of the detoxification was 11 (range 2–17), with the mean dose of chlordiazepoxide used on day one being 140 mg (range 80–225 mg). Conclusions Chlordiazepoxide can be used for outpatient GBL detoxification in combination with a provision for crisis admission to hospital. CIWA-Ar score can be applied to GBL withdrawal to measure severity and inform a reducing regimen of chlordiazepoxide.