This work presents a method to produce conductive and auxetic composite membranes from a biobased and biodegradable matrix: polybutylene succinate (PBS). The conductivity was improved by the addition ...of graphene nanoplatelets (GNP) and the samples were produced via solution electrospinning. The membrane properties were shown to increase with increasing GNP concentration and the rotational speed of the collector. In particular, a membrane having 0.2% w/v GNP and fabricated at the highest collector speed (9.96 m/s) showed the highest electrical conductivity (1.56 × 10−4 S/m) while having a negative Poisson's ratio (NPR) of −1.5 in tension. To complete the analysis, mechanical characterizations showed that the presence of GNP led to a substantial increase in Young's modulus (234%) and tensile strength (190%) compared to the neat PBS membrane produced under the same conditions. Differential scanning calorimetry (DSC) revealed a slight crystallinity increase since GNP are acting as heterogeneous nucleating agents, while thermogravimetric analysis (TGA) showed an improved thermal stability for the GNP/PBS membranes. This unique combination of auxetic and conductive properties can be useful for a wide range of innovative applications such as electronic devices, smart textiles, biomaterials, and biomedical devices.
Highlights
Electrospinning was successful to produce polybutylene succinate (PBS) nanofibers.
A careful control of the processing conditions led to auxetic fiber mats.
Electrically conductive mats were produced by adding graphene nanoplatelets (GNP) to PBS.
The PBS mechanical properties were highly improved (200%) with low GNP content (0.2%).
PBS and GNP were mix in solution to produce electrically conductive nanofibers via electrospinning after optimization of the processing conditions.
Electrospinning is a simple and affordable method of producing nanofibers, offering a large specific surface area and highly porous structures with diameters ranging from nanometers to micrometers. ...This process relies on an electrostatic field, providing precise control over the fiber dimensions and morphologies through parameter optimization and the use of specialized spinnerets and collectors. The paper extensively covers the electrospinning process and parameters, shedding light on the factors influencing electrospinning. It addresses the morphological and structural aspects of electrospun fibers that are used in different applications. Additionally, this paper explores various polymeric and non-polymeric materials used in electrospinning. Furthermore, it investigates the incorporation of fillers during electrospinning, using an electric field to enhance properties and functionality. The review concludes by offering insights into upscaling electrospinning production.
Effects of cotreatment with
(UD) methanolic leaf extract on gentamicin (GM)-induced acute kidney injury were evaluated in rats.
Male Wistar rats (n=32) were separated into four groups. Gentamicin ...(100 mg/kg/day, IP) was injected for eight days with or without UD methanolic extract (200 mg/kg/day, gavage). The renal blood flow (RBF) and systolic blood pressure of rats were recorded. Concentration of creatinine, blood urea nitrogen (BUN), sodium, and potassium and osmolarity were measured in the urine and plasma samples. Oxidative stress level was determined by assessment of the levels of antioxidant power (FRAP) and lipid peroxidation (MDA) in the renal tissue. The renal injury and histopathological changes in the kidney were determined by microscopic evaluations.
Administration of UD extract along with GM, compared to GM group, significantly decreased the amounts of plasma creatinine and BUN, urinary sodium excretion, fractional excretion of sodium and potassium, and MDA levels but significantly increased creatinine clearance, urine osmolarity, renal blood flow and FRAP levels.
The cotreatment of UD extract can attenuate renal injury of GM by reduction of oxidative stress, lipid peroxidation, and oxygen free radicals. The potential nephroprotective effects of UD extract are probably mediated via its antioxidant and anti-inflammatory activity.
Cajal-Retzius cells (CRs) are a class of transient neurons in the mammalian cortex that play a critical role in cortical development. Neocortical CRs undergo almost complete elimination in the first ...two postnatal weeks in rodents and the persistence of CRs during postnatal life has been detected in pathological conditions related to epilepsy. However, it is unclear whether their persistence is a cause or consequence of these diseases. To decipher the molecular mechanisms involved in CR death, we investigated the contribution of the PI3K/AKT/mTOR pathway as it plays a critical role in cell survival. We first showed that this pathway is less active in CRs after birth before massive cell death. We also explored the spatio-temporal activation of both AKT and mTOR pathways and reveal area-specific differences along both the rostro-caudal and medio-lateral axes. Next, using genetic approaches to maintain an active pathway in CRs, we found that the removal of either PTEN or TSC1, two negative regulators of the pathway, lead to differential CR survivals, with a stronger effect in the
model. Persistent cells in this latter mutant are still active. They express more Reelin and their persistence is associated with an increase in the duration of kainate-induced seizures in females. Altogether, we show that the decrease in PI3K/AKT/mTOR activity in CRs primes these cells to death by possibly repressing a survival pathway, with the mTORC1 branch contributing less to the phenotype.
The present study aimed to determine the association between pregnancy-associated plasma protein A (PAPP-A) and Gestational Diabetes Methods (GDM) to detect a risk factor for predicting GDM at ...gestational weeks 11-14.
This analytical prospective study recruited 284 pregnant women presenting to six healthcare centers of Qazvin, Iran from February to December 2016. PAPP-A was measured at gestational weeks 11-14 and glucose tolerance test was conducted at gestational weeks 24-28. The participants were assigned into two groups of exposure (reduced PAPP-A) and non-exposure (normal PAPP-A). The association between GDM and PAPP-A was studied. The number of women in exposure group were 201 and 83 in the non-exposure group. Differences between groups were assessed by the Mann-Whitney, Chi-square, T test, logistic regression analysis and ROC Curve with a significance level of 0.05.
Twenty eight (33.73%) patients of the exposure group and 17 (8.46%) of non-exposure group developed GDM. There was a significant difference between the two groups in terms of GDM (p<0.001) and the risk of GDM was 3.98 fold higher in the exposure group (reduced PAPPA
) than that of the non-exposure group (CI=2.39-6.65, p<0.001). Also, 53.3% of the exposure group and 46.7% of the nonexposure group were diagnosed with GDM (p=0.02). There was a significant difference in GDM between the groups and the risk of GDM was 1.85 times higher in the exposure group (reduced PAPPA MOM) than that in the control group (CI=1.09-3.15, p=0.020). According to the ROC curve results, PAPP-A and MOM are acceptable indicators for predicting GDM.
A low PAPP-A level (MOM, MU/L) as a new risk factor for GDM can help early prediction and prevent maternal and fetal complication by timely treatment.
This work presents a method to produce conductive and auxetic composite membranes from a biobased and biodegradable matrix: polybutylene succinate (PBS). The conductivity was improved by the addition ...of graphene nanoplatelets (GNP) and the samples were produced via solution electrospinning. The membrane properties were shown to increase with increasing GNP concentration and the rotational speed of the collector. In particular, a membrane having 0.2% w/v GNP and fabricated at the highest collector speed (9.96 m/s) showed the highest electrical conductivity (1.56 * 10.sup.-4 S/m) while having a negative Poisson's ratio (NPR) of -1.5 in tension. To complete the analysis, mechanical characterizations showed that the presence of GNP led to a substantial increase in Young's modulus (234%) and tensile strength (190%) compared to the neat PBS membrane produced under the same conditions. Differential scanning calorimetry (DSC) revealed a slight crystallinity increase since GNP are acting as heterogeneous nucleating agents, while thermogravimetric analysis (TGA) showed an improved thermal stability for the GNP/PBS membranes. This unique combination of auxetic and conductive properties can be useful for a wide range of innovative applications such as electronic devices, smart textiles, biomaterials, and biomedical devices.
The field of nanofiber research has been gradually shifting towards sustainable materials, but the main challenges include modifying their properties to fit specific needs and applications. In this ...study, ultrathin and porous biobased poly(butylene succinate) (PBS) membranes were fabricated using electrospinning. The neat PBS polymer was found to be very difficult to process, but defect-free nanofibers were generated by adding cetyltrimethylammonium bromide (CTAB) as a surfactant. To determine the effect of CTAB on PBS membranes, extensive characterization of the newly developed material was performed, including morphology, wettability, water absorption, thermal, mechanical, and hydrolytic degradation properties. Scanning electron microscopy (SEM) showed that adding 0.04% w/v of CTAB produced smooth and beadless nanofibers with an average diameter of 380 nm. The presence of CTAB, as a surfactant, significantly improved the membrane porosity and generated higher hydrophilicity even when starting with an intrinsically hydrophobic material (original PBS). The result was a higher water absorption and hydrolytic degradation of the membrane. On the mechanical side, the surfactant highly improved the elongation at break from 51% for the neat PBS membrane to 192% for the PBS/CTAB membrane with 0.04% w/v CTAB. However, CTAB addition had a negligible effect on thermal stability and crystallinity. The results of this study showed that the high porosity and hydrophilicity of PBS/CTAB electrospun membranes, combined with their outstanding water absorption capacity, elasticity, and biodegradability, present a novel solution for enhancing the performance and functionality of biomaterials in various biomedical fields, especially in tissue engineering and wound dressing applications.
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•Polybutylene succinate (PBS) nanofibers were generated via solution electrospinning.•CTAB (surfactant) was needed to generate stable nanofibers.•Membranes with good wettability and excellent water absorbance were produced by combining PBS and CTAB.•Faster hydrolytic degradation was observed due to CTAB.
The impact of dopamine on synaptic plasticity and cognitive function following seizure is not well understood. Here, using optogenetics in the freely behaving animal, we examined exploratory behavior ...and short-term memory in control and kindled male mice during tonic stimulation of dopaminergic neurons within the ventral tegmental area (VTA). Furthermore, using field potential recording, we compared the effect of dopamine on synaptic plasticity in stratum radiatum and stratum oriens layers of both ventral and dorsal hippocampal CA1 regions, and again in both control and kindled male mice. Our results demonstrate that tonic stimulation of VTA dopaminergic neurons enhances novelty-driven exploration and short-term spatial memory in kindled mice, essentially rescuing the seizure-induced cognitive impairment. In addition, we found that dopamine has a dual effect on LTP in control versus kindled mice, such that application of dopamine prevented LTP induction in slices from control mice, but rescued LTP in slices taken from the kindled animal. Taken together, our results highlight the potential for dopaminergic modulation in improving synaptic plasticity and cognitive function following seizure.
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