Synthesis of Porous BPPO-Based Anion Exchange Membranes for Acid Recovery Via Diffusion Dialysis

Diffusion dialysis (DD) is an anion exchange membrane-based functional separation process used for acid recovery. TMA (trimethylamine) and BPPO (brominated poly (2,6-dimethyl-1,4-phenylene oxide) were utilized in this manuscript to formulate AEMs (anion exchange membranes) for DD (diffusion dialysis) using the phase-inversion technique. FTIR (Fourier transfer infrared) analysis, proton NMR spectroscopy, morphology, IEC (ion exchange capacity), LER (linear expansion ratio), CR (fixed group concentration), WR (water uptake/adsorption), water contact angle, chemical, and thermal stability, were all used to evaluate the prepared membranes. The effect of TMA content within the membrane matrix on acid recovery was also briefly discussed. It was reported that porous AEMs have a WR of 149.6% to 233.8%, IEC (ion exchange capacity) of 0.71 to 1.43 mmol/g, CR (fixed group concentration) that ranged from 0.0046 mol/L to 0.0056 mol/L, LER of 3.88% to 9.23%, and a water contact angle of 33.10° to 78.58°. The UH (acid dialysis coefficients) for designed porous membranes were found to be 0.0043 to 0.012 m/h, with separation factors (S) ranging from 13.14 to 32.87 at the temperature of 25 °C. These observations are comparable to those found in the DF-120B commercial membrane with UH of 0.004 m/h and S of 24.3 m/h at the same temperature (25 °C). This porous membranes proposed in this paper are excellent choices for acid recovery through the diffusion dialysis process.

Diamine Oxidase-Conjugated Multiwalled Carbon Nanotubes to Facilitate Electrode Surface Homogeneity

Carbon nanomaterials have gained significant interest over recent years in the field of electrochemistry, and they may be limited in their use due to issues with their difficulty in dispersion. Enzymes are prime components for detecting biological molecules and enabling electrochemical interactions, but they may also enhance multiwalled carbon nanotube (MWCNT) dispersion. This study evaluated a MWCNT and diamine oxidase enzyme (DAO)-functionalised screen-printed electrode (SPE) to demonstrate improved methods of MWCNT functionalisation and dispersion. MWCNT morphology and dispersion was determined using UV-Vis spectroscopy (UV-Vis) and scanning electron microscopy (SEM). Carboxyl groups were introduced onto the MWCNT surfaces using acid etching. MWCNT functionalisation was carried out using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-Hydroxysuccinimide (NHS), followed by DAO conjugation and glutaraldehyde (GA) crosslinking. Modified C-MWNCT/EDC-NHS/DAO/GA was drop cast onto SPEs. Modified and unmodified electrodes after MWCNT functionalisation were characterised using optical profilometry (roughness), water contact angle measurements (wettability), Raman spectroscopy and energy dispersive X-ray spectroscopy (EDX) (vibrational modes and elemental composition, respectively). The results demonstrated that the addition of the DAO improved MWCNT homogenous dispersion and the solution demonstrated enhanced stability which remained over two days. Drop casting of C-MWCNT/EDC-NHS/DAO/GA onto carbon screen-printed electrodes increased the surface roughness and wettability. UV-Vis, SEM, Raman and EDX analysis determined the presence of carboxylated MWCNT variants from their non-carboxylated counterparts. Electrochemical analysis demonstrated an efficient electron transfer rate process and a diffusion-controlled redox process. The modification of such electrodes may be utilised for the development of biosensors which could be utilised to support a range of healthcare related fields.

Organic monolayers modified by vacuum ultraviolet irradiation for solution-processed organic thin-film transistors

A trimethylsilyl-monolayer modified by vacuum ultraviolet (VUV) light has been investigated for use in solution-processed organic thin-film transistors (OTFTs). The VUV irradiation changed a hydrophobic trimethylsilyl-monolayer formed from hexamethyldisilazane vapor into a hydrophilic surface suitable for solution processing. The treated surface was examined via water contact angle measurement and X-ray photoelectron spectroscopy. An appropriate irradiation of VUV light enabled the formation of a dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) film on a modified monolayer by spin-coating. Consequently, the C8-BTBT-based OTFT with a monolayer modified for an optimal VUV irradiation time exhibited a field-effect mobility up to 4.76 cm2 V−1 s−1. The partial monolayer modification with VUV can be adapted to a variety of solution-processes and organic semiconductors for prospective printed electronics.

Facile Synthesis of Fluorinated Polysilazanes and Their Durable Icephobicity on Rough Al Surfaces

Superhydrophobic Al surfaces with excellent durability and anti-icing properties were fabricated by coating dual-scale rough Al substrates with fluorinated polysilazane (FPSZ). Flat Al plates were etched using an acidic solution, followed by immersion in boiling water to generate hierarchical micro-nano structures on their surfaces. The FPSZ coatings were synthesized by grafting 1H,1H,2H,2H-perfluorodecyltrimethoxysilane (FAS-17), a fluoroalkyl silane), onto methylpolysilazane, an organopolysilazane (OPSZ) backbone. The high water contact angle (175°) and low sliding angle (1.6°) of the FPSZ-coated sample with an FAS-17 content of 17.3 wt% promoted the efficient removal of a frozen ice column with a low ice adhesion strength of 78 kPa at −20.0 °C (70% relative humidity), which was 4.3 times smaller than that of an OPSZ-coated surface. The FPSZ-coated Al surface suppressed ice nucleation, leading to a decrease in ice nucleation temperature from −19.5 to −21.9 °C and a delay in freezing time from 334 to 4914 s at −19.0 °C compared with the OPSZ-coated Al surface. Moreover, after 40 icing–melting cycles the freezing temperature of a water droplet on the FPSZ-coated Al surface remained unchanged, whereas that on the FAS-17-coated Al surface increased from −22.3 to −20.7 °C. Therefore, the durability of the polymeric FPSZ coating was superior to that of the FAS-17 monolayer coating.

Fabrication of 3D scaffolds based on fully biobased unsaturated polyester resins by microstereo-lithography

Additive Manufacturing (AM) technologies are an effective route to fabricate tailor made scaffolds for tissue engineering (TE) and regenerative medicine with microstereo-lithography (µSLA) being one of the most promising techniques to produce high quality 3D structures. Here, we report the crosslinking studies of fully biobased unsaturated polyesters (UPs) with 2-hydroxyethyl methacrylate (HEMA) as the unsaturated monomer (UM), using thermal and µSLA crosslinking processes. The resulting resins were fully characterized in terms of their thermal and mechanical properties. Determination of gel content, water contact angle (WCA), topography and morphology analysis by atomic force microscopy (AFM) and scanning electron microscopy (SEM) were also performed. The results show that the developed unsaturated polyester resins (UPRs) have promising properties for µSLA. In vitro cytotoxicity assays performed with 3T3-L1 cell lines showed that the untreated scaffolds exhibited a maximum cellular viability around 60 %, which was attributed to the acidic nature of the UPRs. The treatment of the UPRs and scaffolds with ethanol (EtOH) improved the cellular viability to 100%. The data presented in this manuscript contribute to improve the performance of biobased unsaturated polyesters in additive manufacturing.

Controlled Frac Height Growth Technique to Avoid Contacting Water-Bearing Layer

Many techniques have been used to model, diagnose and detect fracture dimension and propagation during hydraulic fracturing. Diagnosing fracture dimension growth vs time is of paramount importance to reach the desired geometry to maximize hydrocarbon production potential and prevent contacting undesired fluid zones. The study presented here describes a technique implemented to control vertical fracture growth in a tight sandstone formation being stimulated near a water zone. This gas well was completed vertically as openhole with Multi- Stage Fracturing (MSF). Pre-Fracturing diagnostic tests in combination with high-resolution temperature logs provided evidence of vertical fracture height growth downward toward water zone. Pre-fracturing flowback indicated water presence that was confirmed by lab test. Several actions were taken to mitigate fracture vertical growth during the placement of main treatment. An artificial barrier with proppant was placed in the lower zone of the reservoir before main fracturing execution. The rate and viscosity of fracturing fluids were also adjusted to control the net pressure aiming to enhance fracture length into the reservoir. The redesigned proppant fracturing job was placed into the formation as planned. Production results showed the effectiveness of the artificial lower barrier placed to prevent fracture vertical growth down into the water zone. Noise log consists of Sonic Noise Log (SNL) and High Precision Temperature (HPT) was performed. The log analysis indicated that two major fractures were initiated away from water-bearing zone with minimum water production. Additionally, in- situ minimum stress profile indicated no enough contrast between layers to help confine fracture into the targeted reservoir. Commercial gas production was achieved after applying this stimulation technique while keeping water production rate controlled within the desired range. The approach described in this paper to optimize gas production in tight formation with nearby water contact during hydraulic fracturing treatments has been applied with a significant improvement in well production. This will serve as reference for future intervention under same challenging completion conditions.

Polydopamine Induced Wettability Switching of Cellulose Nanofibers/n-Dodecanethiol Composite Aerogels

The novel wettability switchable cellulose nanofiber- (CNF-) based aerogel was conveniently prepared by polydopamine mediated composition of CNF and n-dodecanethiol. The wettability of aerogels can be controlled by adjusting the PDA and n-dodecanethiol loading content, which leads to a variation of water contact angle from 0-149°. The PDA was coated on cellulose nanofibers via hydrogen bonds and then n-dodecanethiol was anchored onto the scaffolds by Michael addition reaction, which was revealed by XPS and FTIR spectra. The composite aerogel can selectively absorb a series of oily liquids from the oil/water mixture, with the maximum absorption capacity of 68 g/g. This work presented a facile strategy to prepare wettability switchable CNF-based heterogenous aerogel and exhibited the potential of the composite aerogel for oil/water separation.

Wettability and Water Uptake Improvement in Plasma-Treated Alfalfa Seeds

The cultivation of alfalfa (Medicago sativa L.), a forage crop grown worldwide, is negatively affected by hard seed presence. We show that treatment of alfalfa seeds with an inductively coupled radio frequency oxygen plasma improves their surface hydrophilicity, as determined by water contact angle (WCA) measurements and water uptake. Furthermore, we see that these effects are mediated by functionalization and etching of the alfalfa seed surface. Surface chemistry is analyzed by X-ray photoelectron spectroscopy (XPS), while morphology is viewed using scanning electron microscopy (SEM). Plasma produces effective alfalfa seed hydrophilization with a variety of treatment parameters. With its potential for fine-tuning, plasma modification of seed wettability shows promise for introduction into agricultural practice.

Synthesis, Hydrophilicity and Micellization of Coil–Brush Polystyrene-b-(polyglycidol-g-polyglycidol) Copolymer—Comparison with Linear Polystyrene-b-Polyglycidol

In this paper, an original method of synthesis of coil–brush amphiphilic polystyrene-b-(polyglycidol-g-polyglycidol) (PS-b-(PGL-g-PGL)) block copolymers was developed. The hypothesis that their hydrophilicity and micellization can be controlled by polyglycidol blocks architecture was verified. The research enabled comparison of behavior in water of PS-b-PGL copolymers and block–brush copolymers PS-b-(PGL-g-PGL) with similar composition. The coil–brush copolymers were composed of PS-b-PGL linear core with average DPn of polystyrene 29 and 13 of polyglycidol blocks. The DPn of polyglycidol side blocks of coil–b–brush copolymers were 2, 7, and 11, respectively. The copolymers were characterized by 1H and 13C NMR, GPC, and FTIR methods. The hydrophilicity of films from the linear and coil–brush copolymers was determined by water contact angle measurements in static conditions. The behavior of coil–brush copolymers in water and their critical micellization concentration (CMC) were determined by UV-VIS using 1,6-diphenylhexa-1,3,5-trien (DPH) as marker and by DLS. The CMC values for brush copolymers were much higher than for linear species with similar PGL content. The results of the copolymer film wettability and the copolymer self-assembly studies were related to fraction of hydrophilic polyglycidol. The CMC for both types of polymers increased exponentially with increasing content of polyglycidol.

High prevalence of urinary schistosomiasis in a desert population: results from an exploratory study around the Ounianga lakes in Chad

Background Researching a water-borne disease in the middle of the Sahara desert might not seem the most relevant concern. However, nomadic Sahelian pastoralists health concerns regarding their livestock and anecdotal reports about trematode infections of Fasciola spp. and Schistosoma spp. in desert-raised animals justified an exploratory study focusing on the lakes of Ounianga in Northern Chad. The aim was to test whether trematode parasites such as Schistosoma spp. occur in human populations living around the Sahara desert lakes of Ounianga Kebir and Ounianga Serir in northern Chad. Methods The study was carried out in January 2019 and comprised of three components. First, a cross sectional survey based on a random sample drawn from the population to detect infections with S. haematobium and S. mansoni; second, focus group discussions exploring disease priorities, access to health and health seeking behaviour; and third, surveying water contact sites for intermediate host snails. Samples of trematode parasites and snails were confirmed on species level by molecular genetic methods. For parasitological and malacological surveys descriptive statistics were performed. Qualitative data analysis included the full review of all transcripts, followed by a descriptive and explorative thematic analysis. Results Among 258 participants, the overall S. haematobium prevalence using urine filtration was 39.2% [95% confidence interval (CI): 33.5–45.1%], with 51.5% of the infected suffering from heavy infection. The intermediate host snail of S. haematobium (Bulinus truncatus) occurred at water contact sites near both study villages, revealing the potential for local transmission. Although a positive S. mansoni point-of-care circulating cathodic antigen (POC-CCA) test result was obtained from 8.6% (95% CI 5.7–12.8%) of the samples, no intermediate host snails of S. mansoni were found, and the relevance of S. mansoni remains uncertain. Qualitative findings underline the importance of morbidity caused by urinary schistosomiasis, and the lack of access to diagnostics and treatment as a major health concern. Conclusions This research revealed a high prevalence of urinary schistosomiasis in the population living around the lakes of Ounianga in the Sahara, a United Nations Educational, Scientific and Cultural Organization (UNESCO) world heritage site in Chad. Despite the high public health importance of the associated morbidity expressed by the population, there is no access to diagnostics and treatment. Further work is needed to develop and test a context-adapted intervention. Graphical Abstract