The influence of tetraethoxysilane sol preparation on the electrospinning of silica nanofibers

The critical parameters determining the electrospinning of silica nanofibers starting from tetraethoxysilane sols are reported. By controlling the reaction conditions, the rheological properties of the sol allowed for electrospinning without needing the addition of an organic polymer. This allows the polymer removal step, which is deleterious to the fibers and an economic and ecological inconvenience, to be skipped. The effects on the electrospinning process of the viscosity of the sol, the concentration of ethanol, the degree of crosslinking and the size of the colloidal species were studied in depth with ATR-FTIR, Si-29 NMR, H-1 NMR and DLS. Moreover, to separate the contributions of the different parameters three different set-ups for sol preparation were used. An optimum amount of 9 mol L-1 ethanol for electrospinning was determined. In addition, the optimum degree of crosslinking and size of colloidal particles, approximately 3.5-7 nm, were obtained for stable electrospinning and for producing uniform, beadless nanofibers that were stable in time. The optimum viscosity range is in between 100 and 200 mPa s, which is in line with previous work. Using these optimum conditions, continuous electrospinning was carried out for 3 h, resulting in large flexible silica nanofibrous membranes

Critical Behaviour of Non-Equilibrium Phase Transitions to Magnetically Ordered States

We describe non-equilibrium phase transitions in arrays of dynamical systems with cubic nonlinearity driven by multiplicative Gaussian white noise. Depending on the sign of the spatial coupling we observe transitions to ferromagnetic or antiferromagnetic ordered states. We discuss the phase diagram, the order of the transitions, and the critical behaviour. For global coupling we show analytically that the critical exponent of the magnetization exhibits a transition from the value 1/2 to a non-universal behaviour depending on the ratio of noise strength to the magnitude of the spatial coupling.Comment: 4 pages, 5 figure

Supplementing goat kids with coconut medium chain fatty acids in early life influences growth and rumen papillae development until 4 months after supplementation but effects on in vitro methane emissions and the rumen microbiota are transient

The aim of this study was to investigate the methane (CH4) reducing potential of a combination of prenatal and/or postnatal treatment with coconut oil medium chain fatty acids (CO MCFA) in goat kids. The hypothesis is that influencing rumen function during early life has more chances for success than in the adult life, related to the resilience of the mature rumen microbiota. Forty-eight pregnant does were split into two experimental groups: treated does (D+) received 40 g/d of CO MCFA in a test compound feed, while control does (D-) received a control compound feed, during the last 3 wk of gestation. Twin kids from 10 does of each group were split up into a treated (K+) and nontreated (K-) group, resulting in four experimental groups: D+ K+, D+ K-, D-K+, and D-K-. The K+ kids received 1.8 mL/d of CO MCFA from birth until 2-wk postweaning (11 wk). Irrespective of treatment, the experimental rearing conditions resulted in absence of rumen protozoa at all sampling times, assessed by quantitative PCR (qPCR). In vitro incubations with rumen fluid at 4 wk old showed 82% lower CH4 production of inoculum from D+ K+ kids compared to D-K-kids (P = 0.01). However, this was accompanied by lower total volatile fatty acids (tVFA) production (P = 0.006) and higher hydrogen accumulation (P = 0.008). QPCR targeting the mcrA and rrs genes confirmed a lower abundance of total methanogens (P < 0.02) and total eubacteria (P = 0.02) in D+ K+ kids at 4 wk old. Methanogenic activity, as assessed by mcrA expression by RT-qPCR, was also lower in these kids. However, activity did not always reflect methanogen abundance. At 11 and 28 wk old, prenatal and postnatal effects on in vitro fermentation and rumen microbiota disappeared. Nevertheless, lower milk replacer intake in the first 4 wk resulted in reduced BW in K+ kids, persisting until 28 wk of age. Additionally, differences assigned to postnatal treatment were found in papillae density, width, and length in different areas of the rumen, recorded at 28 wk old. Conclusion: prenatal and postnatal supplementation with CO MCFA reduced in vitro CH4 emissions until 4 wk old by depressing methanogen abundance and activity but at the expense of rumen fermentation and eubacterial abundance. Unfortunately, daily gain of K+ kids was suppressed. Some rumen papillae characteristics differed at 28 wk old due to postnatal treatment which ended at 11 wk old, indicating rumen papillary development can be affected by the early-life nutritional circumstances

Cation-pi Interactions accelerate the living cationic ring-opening polymerization of unsaturated 2-alkyl-2-oxazolines

Cation-dipole interactions were previously shown to have a rate-enhancing effect on the cationic ring-opening polymerization (CROP) of 2-oxazolines bearing a side-chain ester functionality. In line with this, a similar rate enhancement-via intermolecular cation-pi interactions-was anticipated to occur when pi-bonds are introduced into the 2-oxazoline side-chains. Moreover, the incorporation of pi-bonds allows for facile postfunctionalization of the resulting poly(2-oxazoline)s with double and triple bonds in the side-chains via various click reactions. Herein, a combined molecular modeling and experimental approach was used to study the CROP reaction rates of 2-oxazolines with side-chains having varying degrees of unsaturation and side-chain length. The presence of cation-pi interactions and the influence of the degree of unsaturation were initially confirmed by means of regular molecular dynamics simulations on pentameric systems. Furthermore, a combination of enhanced molecular dynamics simulations, static calculations, and a thorough analysis of the noncovalent interactions was performed to unravel to what extent cation-pi interactions alter the reaction kinetics. Additionally, the observed trends were confirmed also in the presence of acetonitrile as solvent, in which experimentally the polymerization is performed. Most intriguingly, we found only a limited effect on the intrinsic reaction kinetics of the CROP and a preorganization effect in the reactive complex region. The latter effect was established by the unsaturated side-chains and the cationic center through a complex interplay between cation-pi, pi-pi, pi-induced dipole, and cation-dipole interactions. These findings led us to propose a two-step mechanism comprised of an equilibration step and a CROP reaction step. The influence of the degree of unsaturation, through a preorganization effect, on the equilibration step was determined with the following trend for the polymerization rates: n-ButylOx = PentynOx. The trend was experimentally confirmed by determining the polymerization rate constants

Vestibular Infant Screening (VIS)–Flanders : results after 1.5 years of vestibular screening in hearing-impaired children

Due to the close anatomical relationship between the auditory and vestibular end organs, hearing-impaired children have a higher risk for vestibular dysfunction, which can affect their (motor) development. Unfortunately, vestibular dysfunction often goes unnoticed, as vestibular assessment in these children is not standard of care nowadays. To timely detect vestibular dysfunction, the Vestibular Infant Screening–Flanders (VIS–Flanders) project has implemented a basic vestibular screening test for hearing-impaired infants in Flanders (Belgium) with a participation rate of 86.7% during the first year and a half. The cervical Vestibular Evoked Myogenic Potentials (cVEMP) test was applied as vestibular screening tool to map the occurrence of vestibular (mainly saccular) dysfunction in this population. At the age of 6 months, 184 infants were screened. No refers on vestibular screening were observed in infants with permanent conductive hearing loss. In infants with permanent sensorineural hearing loss, a cVEMP refer rate of 9.5% was observed. Failure was significantly more common in infants with severe-profound compared to those with mild-moderate sensorineural hearing loss (risk ratio = 9.8). Since this is the first regional study with a large sample size and successful participation rate, the VIS–Flanders project aims to set an example for other regions worldwide

The social context of severe child malnutrition: A qualitative household case study from a rural area of the Democratic Republic of Congo

Introduction The magnitude of child malnutrition including severe child malnutrition is especially high in the rural areas of the Democratic Republic of Congo (the DRC). The aim of this qualitative study is to describe the social context of malnutrition in a rural part of the DRC and explore how some households succeed in ensuring that their children are well-nourished while others do not. Methodology This study is based on participant observation, key informant interviews, group discussions and in-depth interviews with four households with malnourished children and four with well-nourished children. We apply social field theory to link individual child nutritional outcomes to processes at local level and to the wider socio-economic environment. Findings We identified four social fields that have implications for food security and child nutritional outcomes: 1) household size and composition which determined vulnerability to child malnutrition, 2) inter-household cooperation in the form of ‘gbisa work party’ which buffered scarcity of labour in peak seasons and facilitated capital accumulation, 3) the village associated with usufruct rights to land, and 4) the local NGO providing access to agricultural support, clean drinking water and health care. Conclusions Households that participated in inter-household cooperation were able to improve food and nutrition security. Children living in households with high pressure on productive members were at danger of food insecurity and malnutrition. Nutrition interventions need to involve local institutions for inter-household cooperation and address the problem of social inequalities in service provision. They should have special focus on households with few resources in the form of land, labour and capita

Improving flubendazole efficiency through time-stable electrospun amorphous solid dispersions

Over 2/3rd of all newly developed drugs are rendered useless because they don't dissolve in our stomach. Their high crystallinity prevents any active ingredients from entering our system. For this reason, increasing the aqueous solubility of poorly soluble drugs is highly researched. Solvent electrospinning of a solution of the flubendazole and poly(2-ethyl-2-oxazoline) is demonstrated to be a viable strategy to produce stable nanofibrous amorphous solid dispersions with ultrahigh drug-loadings (up to 55 wt\% flubendazole). Importantly, at such high drug loadings, the concentration of the polymer in the electrospinning solution has to be lowered below the concentration where it can be spun in absence of the drug as the interactions between the polymer and the drug result in increased solution viscosity. X-ray diffraction results and in vitro drug release studies confirm the remarkable amorphous stability and potential of this electrospinning formulation strategy by significantly increased drug solubility values and dissolution rates even after storing the formulation for one year

Improving Flubendazole Efficiency Through Time-Stable Electrospun Amorphous Solid Dispersions

Over 2/3rd of all newly developed drugs are rendered useless because they don’t dissolve in our stomach. Their high crystallinity prevents any active ingredients from entering our system. For this reason, increasing the aqueous solubility of poorly soluble drugs is highly researched. Solvent electrospinning of a solution of the flubendazole and poly(2-ethyl-2-oxazoline) is demonstrated to be a viable strategy to produce stable nanofibrous amorphous solid dispersions with ultrahigh drug-loadings (up to 55 wt% flubendazole). Importantly, at such high drug loadings, the concentration of the polymer in the electrospinning solution has to be lowered below the concentration where it can be spun in absence of the drug as the interactions between the polymer and the drug result in increased solution viscosity. X-ray diffraction results and in vitro drug release studies confirm the remarkable amorphous stability and potential of this electrospinning formulation strategy by significantly increased drug solubility values and dissolution rates even after storing the formulation for one year