Fiber Size Distribution Research Articles

Effect of the fibre diameter polydispersity on the permeability of nonwoven filter media

AbstractThis paper studies the permeability values of air filter media obtained by 3‐D simulations using the GeoDict® code. 3‐D fibrous structures with different specific characteristics that can be encountered in air filtration (0.03 ≤ solid volume fraction [α] ≤ 0.25, monodisperse fibres [1 μm ≤ df ≤8 μm], or polydisperse fibres) were generated. For monodisperse fibres, the permeability values obtained were compared with various correlations identified in the literature. After confirming that Davies' or Jackson and James' relations allowed a good estimate of the permeability, it is shown that the modified Happel's correlation provides a better prediction. In the case of normal (standard deviation: σ ≤ 1.5) or lognormal fibre size distribution (geometric standard deviation: σG ≤ 2), this modified Happel's correlation, in which the fibre diameter is replaced by an equivalent fibre diameter, leads to a relative deviation of less than ±8% and ±4% for lognormal and normal fibre distributions, respectively. The comparison with experimental permeability values obtained on real media provides quite encouraging results.

A baseline assessment of the relationship between microplastics and plasticizers in sediment samples collected from the Barcelona continental shelf.

It has been suggested that the seafloor may be a sink for the plastic debris that enters the ocean. Therefore, the collection of data in the seafloor sediments regarding the co-presence of microplastics (MPs) and contaminants associated to plastic is considered a relevant topic. However, the number of studies addressing their possible correlation in this environment is still limited, and very little is known about the mechanisms that determine the release of plastic additives from plastic items. Starting from this basis, we investigated the presence of MPs and eleven phthalic acid esters (PAEs) in the continental shelf offshore Barcelona. Following a shelf-slope continuum approach, we sampled sediments from five stations, and we performed analysis by means of infrared micro spectroscopy (µFTIR) and liquid chromatography tandem mass spectrometry (LC-MS/MS). MPs were found to range from 62.0 to 931.1 items/kg d.w. with maximum concentration in the submarine canyon Besòs and at the highest depth. Moreover, different trends in the size distribution of fibers and non-fibers were observed, indicating the occurrence of a size dependent selection mechanism during transport and accumulation. PAEs resulted comprised between 1.35 to 2.41mg/kg with Di(2-ethylhexyl)phthalate (DEHP) the most abundant congeners (1.04mg/kg). Statistical analysis revealed no correlation between the Σ11PAEs and the total MPs concentration, but correlation between DEHP and fibers (σ = 0.667, p = 0,037), that resulted both correlated to the distance to the coast (ρ = 0.941 with p = 0,008 and ρ = 0.673 with p = 0.035, respectively).

Loss of FoxOs in muscle increases strength and mitochondrial function during aging.

Muscle mitochondrial decline is associated with aging-related muscle weakness and insulin resistance. FoxO transcription factors are targets of insulin action and deletion of FoxOs improves mitochondrial function in diabetes. However, disruptions in proteostasis and autophagy are hallmarks of aging and the effect of chronic inhibition of FoxOs in aged muscle is unknown. This study investigatedthe role of FoxOs in regulating muscle strength and mitochondrial function with age. We measured muscle strength, cross-sectional area, muscle fibre-type, markers of protein synthesis/degradation, central nuclei, glucose/insulin tolerance, and mitochondrial bioenergetics in 4.5-month (Young) and 22-24-month-old (Aged) muscle-specific FoxO1/3/4 triple KO (TKO) and littermate control (Ctrl) mice. Lean mass was increased in Aged TKO compared with both Aged Ctrl and younger groups by 26-33% (P<0.01). Muscle strength, measured by max force of tibialis anterior (TA) contraction, was 20% lower in Aged Ctrl compared with Young Ctrls (P<0.01) but was not decreased in Aged TKOs. Increased muscle strength in Young and Aged TKO was associated with 18-48% increased muscle weights compared with Ctrls (P<0.01). Muscle cross-sectional analysis of TA, soleus, and plantaris revealed increases in fibre size distribution and a 2.5-10-fold increase in central nuclei in Young and Aged TKO mice, without histologic signs of muscle damage. Age-dependent increases in Gadd45a and Ube4a expression as well accumulation of K48 polyubiquitinated proteins were observed in quad and TA but were prevented by FoxO deletion. Young and Aged TKO muscle showed minimal changes in autophagy flux and no accumulation of autophagosomes compared with Ctrl groups. Increased strength in Young and Aged TKO was associated with a 10-20% increase in muscle mitochondrial respiration using glutamate/malate/succinate compared with controls (P<0.05). OXPHOS subunit expression and complex I activity were decreased 16-34% in Aged Ctrl compared with Young Ctrl but were prevented in Aged TKO. Both Aged Ctrl and Aged TKO showed impairedglucose tolerance by 33% compared to young groups (P<0.05) indicating improved strength and mitochondrial respiration are not due to improved glycemia. FoxO deletion increases muscle strength even during aging. Deletion of FoxOs maintains muscle strength in part by mild suppression of atrophic pathways, including inhibition of Gadd45a and Ube4a expression, without accumulation of autophagosomes in muscle. Deletion of FoxOs also improved mitochondrial function by maintenance of OXPHOS in both young and aged TKO.

BIOLOGICAL BEHAVIOUR OF CHITOSAN ELECTROSPUN NANOFIBROUS MEMBRANES AFTER DIFFERENT NEUTRALISATION METHODS

Chitosan electrospun nanofibres were synthesised in two different trifluoroacetic acid (TFA)/dichloromethane (DCM) solvent ratios and then neutralised in aqueous and ethanol sodium-based solutions (NaOH and Na2CO3) to produce insoluble materials with enhanced biological properties for regenerative and tissue engineering applications. Structural, electronic, and optical properties and the swelling capacity of the prepared nanofibre membrane were studied by scanning electron microscopy, Fourier-transform infrared spectroscopy, and photoluminescence. Cell viability (with the U2OS cell line) and antibacterial properties (against Staphylococcus aureus and Escherichia coli) assays were used to assess the biomedical potential of the neutralised chitosan nanofibrous membranes. A 7:3 TFA/DCM ratio allows for an elaborate nanofibrous membrane with a more uniform fibre size distribution. Neutralisation in aqueous NaOH only maintains a partial fibrous structure. At the same time, neutralisation in NaOH ethanol-water maintains the structure during 1 month of degradation in phosphate-buffered saline and distilled water. All membranes demonstrate high biocompatibility, but neutralisation in ethanol solutions affects cell proliferation on materials made with 9:1 TFA/DCM. The prepared nanofibrous mats could constrain the growth of both gram-positive and gram-negative microorganisms, but 7:3 TFA/DCM membranes inhibited bacterial growth more efficiently. Based on structural, degradation, and biological properties, 7:3 TFA/DCM chitosan nanofibrous membranes neutralised by 70% ethanol/30% aqueous NaOH exhibit potential for biomedical and tissue engineering applications.

SEDDS-loaded mucoadhesive fiber patches for advanced oromucosal delivery of poorly soluble drugs.

To date, buccal administration of lipophilic drugs is still a major challenge due to their poor solubility in saliva and limited penetration into mucosal tissues. To overcome these limitations, we developed electrospun patches combining the benefits of mucoadhesive fibers and self-emulsifying drug delivery systems (SEDDS). The fiber system comprises a combination of mucoadhesive thiolated polyacrylic acid fibers and SEDDS-loaded fibers fabricated by parallel electrospinning. The resulting mucoadhesive electrospun SEDDS patches were systemically investigated for fiber characteristics, self-emulsification, mucoadhesion, drug penetration into porcine buccal tissue and biocompatibility. The patches showed high encapsulation efficiency for SEDDS without causing fiber defects or leakage. SEDDS incorporation enhanced the spinning process and reduced the fiber diameter and fiber size distribution. Hydration-dependent self-emulsification provided a controlled release of curcumin being encapsulated in nano-scaled o/w emulsion for over 3h. Due to the thiolated polyacrylic acid fibers, the buccal residence time of patches was 200-fold prolonged. Further, they promoted a significantly increased drug penetration into buccal tissue compared to fiber patches without SEDDS. Finally, biocompatibility and improved therapeutic effects of curcumin-loaded patches on human keratinocytes and fibroblasts were confirmed. Mucoadhesive electrospun SEDDS patches represent a promising approach to overcome current challenges in the oromucosal delivery of lipophilic drugs to unlock their full therapeutic potential.

Kollajen/Jelatin/Bal Esaslı Çift Katmanlı Doku İskelesi Üretimi ve Karakterizasyonu

In this project, a porous tissue scaffold composed of collagen/gelatin, which are natural, biocompatible, and biodegradable polymers, was fabricated by lyophilization, then a nanofibrous gelatin/polyethylene oxide (PEO)/honey blend was accumulated onto this layer via the electro-spinning process. The tissue scaffold was cross-linked by treating with glutaraldehyde vapor followed by EDC/NHS reagents. For the characterization, Fourier Transformed Infrared (FTIR) spectroscopy, Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), pore size distribution analysis, and aqueous degradation tests were performed. While the lyophilized layer was fabricated by 1:1 (w/w) collagen/gelatin mixture, the top layer was electro-spun onto this layer by selecting the most appropriate blend ratio (2:2:2 w/w, %6 w/v total material). The lyophilized scaffold layer had a wide pore size distribution in the 5−200 µm range. After the cross-linking, pore size distribution became more homogenous (concentrating around 30−40 µm). According to SEM analysis, a uniform fiber size distribution (Dave = 423 ± 85 nm) was obtained and after the cross-linking and rinsing processes a slight fiber fusion occurred. Regarding the TGA and degradation results, the scaffold robustness increased after the cross-linking. Overall, the developed tissue scaffold with its stable, porous and fibrous form could be a suitable candidate for different tissue engineering applications.

The Significance of Multi-Size Carbon Fibers on the Mechanical and Fracture Characteristics of Fiber Reinforced Cement Composites

One of the main challenges of using a high fiber volume content in a cement composite is the narrow margin of fiber volume content beyond which fibers can cause an adverse effect on the mechanical properties. In this paper, the significance of fiber size distribution and fiber volume content of different proportions of chopped and milled carbon microfibers are investigated. The mixes’ flowability showed improvement with altering the fiber size distribution despite having a high fiber content. Uniaxial compression cylinders and unnotched and notched beams were cast and then tested at 7 and 28 days of age. It was found that the compressive strength is significantly affected by fiber size distribution more than fiber volume content. On the other hand, the modulus of rupture and fracture toughness are proportional to the fiber volume content with little effect of fiber size distribution. Finally, neither high fiber volume content nor altered fiber size distribution significantly affected the elastic modulus of the fiber cement composites.

Tri-Layered Doxycycline-, Collagen- and Bupivacaine-Loaded Poly(lactic-co-glycolic acid) Nanofibrous Scaffolds for Tendon Rupture Repair.

Achilles tendon rupture is a severe injury, and its optimal therapy remains controversial. Tissue engineering scaffolds play a significant role in tendon healing and tissue regeneration. In this study, we developed tri-layered doxycycline/collagen/bupivacaine (DCB)-composite nanofibrous scaffolds to repair injured Achilles tendons. Doxycycline, collagen, and bupivacaine were integrated into poly(lactic-co-glycolic acid) (PLGA) nanofibrous membranes, layer by layer, using an electrospinning technique as healing promoters, a 3D scaffold, and painkillers, respectively. After spinning, the properties of the nanofibrous scaffolds were characterized. In vitro drug discharge behavior was also evaluated. Furthermore, the effectiveness of the DCB–PLGA-composite nanofibers in repairing ruptured Achilles tendons was investigated in an animal tendon model with histological analyses. The experimental results show that, compared to the pristine PLGA nanofibers, the biomolecule-loaded nanofibers exhibited smaller fiber size distribution and an enhanced hydrophilicity. The DCB-composite nanofibers provided a sustained release of doxycycline and bupivacaine for over 28 days in vivo. Additionally, Achilles tendons repaired using DCB-composite nanofibers exhibited a significantly higher maximum load-to-failure than normal tendons, suggesting that the biomolecule-incorporated nanofibers are promising scaffolds for repairing Achilles tendons.

Development of a traditional Chinese medicine-based agent for the treatment of cancer cachexia.

BackgroundDespite recent advances in understanding the pathophysiology of cancer cachexia, prevention/treatment of this debilitating disease remains an unmet medical need.MethodsWe developed an integrated, multi‐tiered strategy involving both in vitro and in vivo muscle atrophy platforms to identify traditional Chinese medicine (TCM)‐based anti‐cachectic agents. In the initial screening, we used inflammatory cytokine‐induced atrophy of C2C12 myotubes as a phenotypic screening platform to assess the protective effects of TCMs. The selected TCMs were then evaluated for their abilities to protect Caenorhabditis elegans from age‐related reduction of mobility and contractility, followed by the C‐26 colon adenocarcinoma mouse model of cachexia to confirm the anti‐muscle atrophy effects (body/skeletal muscle weights, fibre size distribution, grip strengths, and serum IL‐6). Transcriptome analysis, quantitative real‐time polymerase chain reaction, and immunoblotting were performed to gain understanding of the potential mechanism(s) by which effective TCM protected against C26 tumour‐induced muscle atrophy.ResultsOf 29 widely used TCMs, Dioscorea radix (DR) and Mu Dan Pi (MDP) showed a complete protection (all P values, 0.0002) vis‐à‐vis C26 conditioned medium control in the myotube atrophy platform. MDP exhibited a unique ability to ameliorate age‐associated decreases in worm mobility, accompanied by improved total body contractions, relative to control (P < 0.0001 and <0.01, respectively), which, however, was not noted with DR. This differential in vivo protective effect between MDP and DR was also confirmed in the C‐26 mouse model. MDP at 1000 mg/kg (MDP‐H) was effective in protecting body weight loss (P < 0.05) in C‐26 tumour‐bearing mice without changing food or water intake, accompanied by the restoration of the fibre size distribution of hindleg skeletal muscles (P < 0.0001) and the forelimb grip strength (P < 0.05). MDP‐treated C‐26‐tumour‐bearing mice were alert, showed normal posture and better body conditions, and exhibited lower serum IL‐6 levels (P = 0.06) relative to vehicle control. This decreased serum IL‐6 was associated with the in vitro suppressive effect of MDP (25 and 50 μg/mL) on IL‐6 secretion into culture medium by C26 cells. RNA‐seq analysis, followed by quantitative real‐time polymerase chain reaction and/or immunoblotting, shows that MDP's anti‐cachectic effect was attributable to its ability to reverse the C‐26 tumour‐induced re‐programming of muscle homoeostasis‐associated gene expression, including that of two cachexia drivers (MuRF1 and Atrogin‐1), in skeletal muscles.ConclusionsAll these findings suggest the translational potential of MDP to foster new strategies for the prevention and/or treatment of cachexia. The protective effect of MDP on other types of muscle atrophy such as sarcopenia might warrant investigations.

Exposure to textile microfibers causes no effect on blood, behavior and tissue morphology in the three-spined stickleback (Gasterosteus aculeatus)

We assessed textile microfibers impacts on the three-spined stickleback, using synthetic and natural fibers originating from yarns or washer effluents. After water exposure at 200 fibers/L, we assessed fish survival, behavior, tissue morphology and hemoglobin concentration, and paid special attention to exposure characterization. We report quantitative fiber distribution in the exposure system, fiber size distribution, and contamination. We provide a fiber preparation procedure and exposure method intended to ensure accurate and stable concentrations over time. Following exposure, no effect was observed on the studied endpoints in any of the treatment conditions. We observed fast sinking of the fibers. Fish organs and feces contained 1.3% and 6.8% of recovered fibers, and 12.6% fibers were found adhered to the tank walls. We show that water renewals in semi-static exposures is a critical step for the maintenance of stable concentrations, and discuss the practical and/or methodological challenges associated to the study of microfibers.

Metal sulfide nano-frameworks anchored into 3D honeycomb-like porous carbon nanofibers as freestanding anodes for high performance lithium-ion batteries

Exploring advanced electrode materials with high lithium storage capacity and long cycling stability is of great importance for further development of lithium-ion batteries (LIBs). Herein, metal sulfide nano-frameworks anchored into 3D honeycomb-like porous carbon nanofibers are well designed and fabricated by electro-blowing spinning method and subsequent carbonization process. The effects of Ni/Co ratios on the nano-frameworks particle size, specific surface area and pore size distribution of fibers are systematically studied. Noticeably, the obtained fibers are crosslinked with each other to form a network film using as freestanding anode of LIBs, which avoids the cumbersome slurry-casting process. Moreover, the porous metal sulfide nano-frameworks meet the demand of high capacity while offering abundant cavities to accommodate volume expansion. More importantly, the 3D honeycomb-like porous carbon nanofibers as an ideal matrix not only provide enough buffer zones to alleviate volume expansion, but also shorten the diffusion pathways of electrons/ions. Benefiting from the advantages of structural feature, the optimized freestanding anode delivers an excellent lithium storage performance, including a high reversible capacity of 736 mAh g−1 after 200 cycles at 0.2 A g−1 and a long cycling stability of 73.5% capacity retention after 500 cycles at 1 A g−1.

Flexible Cotton Fiber-Based Composite Films with Excellent Bending Stability and Conductivity at Cryogenic Temperature.

The commonly used metal thin film or resin-based flexible composites cannot meet the requirement of cryogenic flexible conductive functional devices, which may be used in space exploration, biomedicine, and other science and technology fields facing a very low temperature environment, because of their poor fatigue and anti-bending properties at cryogenic temperature. In this work, a composite based on functionalized cotton fibers is proposed to achieve the application requirement of flexible electrical systems at cryogenic temperature. A conductive composite film with optimized strength and flexibility was obtained by controlling the size distribution of cotton fibers and adjusting the interaction force among the cotton fibers. The obtained composite film could endure over 10,000 times of bending at 77 K (-196 °C), with the resistance changing less than ±5%, indicating its excellent mechanical flexibility and electrical stability at cryogenic temperature. Finally, a demonstration was successfully conducted by applying the composite film as a flexible electrical connection to a robot arm, which worked at 77 K. This work might be a reference significance for the application of flexible conductors from room temperature to cryogenic temperature.

Prediction of filtration performance of compressed fibrous media

Fibrous filter media is usually subjected to compression in practice. However, the effect of compression on the pore structure, flow field and filtration performance of heterogeneous compressed filter media has not been studied well. In this work, the filtration performance of two fibrous filter media with different compressions was investigated by experiments, classical single fiber efficiency theory and simulations. Artificial 3-D structures were established via GeoDict software based on the parameters of real uncompressed fibrous filter media. There was good agreement between the experimental and simulated results. For compressed filter media, it was found that the equivalent fiber diameter increased with increasing compression ratio. After compression, a shift in the pore size distribution and an increase in the channel tortuosity can be observed. The filtration performance varies for different compressed filter media. In addition, the filtration efficiency decreases as the angle between the fibers and the X-Y plane increases. There is a decrease in the penetration for structures with a broader fiber size distribution. Not only the real fiber size distribution and orientation but also the variation in fiber diameters with compression should be considered when predicting or calculating the performance of compressed filter media.

The cellular basis of compensatory muscle growth in the teleost Odontesthes bonariensis.

This study evaluates white muscle growth and in vivo cell proliferation during a fasting and refeeding trial, using pejerrey (Odontesthes bonariensis) as animal model, in order to better understand the cellular basis governing catch-up growth. Experiments consisted of two groups of fish, a control group continuously fed ad libitum, and a group fasted for 2 weeks and then fed for another 2 weeks. We examined how the formation of new muscle fibers and their increase in size were related to muscle precursor cell (MPC) proliferation under both experimental conditions. During fasting, the number of 5-ethynyl-2'-deoxyuridine-positive (EdU+) cells decreased along with myogenic regulatory factor (MRF) mRNA levels related to myoblast proliferation and differentiation, and the muscle stem cell marker Pax7 mRNA level increased. Analysis of myomere cross-sectional area, distribution of muscle fiber sizes and number of fibers per myomere showed that muscle hypertrophy but not hyperplasia was inhibited during fasting. Both higher igf2 mRNA level and the persistence of cell proliferation could be supporting new myofiber formation. In contrast, an exacerbated MPC proliferation occurred during catch-up growth, and this increase in cell number could be contributing to the growth of both pre-existing and newly formed small fibers. The findings that some MPCs proliferate during fasting and that muscle growth mechanisms, hyperplasia and hypertrophy are differentially regulated could help to explain why re-fed fish could grow at faster rates, and why they return to the lost growth trajectory.

The influence of moisture content on dust generation in falling curtains of sugarcane bagasse fiber

Bagasse fiber, typically containing 50% moisture, is burned to generate electricity and steam. Pre-combustion drying of fiber increases boiler energy efficiency and steam production, and has been demonstrated to reduce environmental impacts. However, uncertainty surrounding dust explosions are limiting its uptake and bagasse dust has potentially harmful health impacts. Here we propose new methods to assist in assessing dust liberation in bagasse fiber drying. Quantification of liberated combustible dust from bagasse fiber across a typical range of post-drying moisture contents (30 to 45 wt%) was undertaken. Laser diffraction and sieving techniques were used to characterise bagasse fiber and dust particle size distributions, as well as quantify the mass fraction of dust liberated during cascading drying operations. Moisture content was found to significantly influence the liberation of combustible dust, defined as particles in the sub-425 μm range. Drying from 45 to 30% moisture led to a 260% increase in liberated dust particles. Image analysis of dust clouds in falling fiber curtains were used to qualitatively assess and confirm the observations from the dust liberation sieving method. Scanning electron microscope imaging and dust particle specific surface area analysis provide further valuable insights into bagasse material properties that contribute to increased risk during drying.

Occurrence and size distribution of microplastics in mudflat sediments of the Cowichan-Koksilah Estuary, Canada: A baseline for plastic particles contamination in an anthropogenic-influenced estuary

Documenting the prevalence of microplastics in marine-coastal ecosystems serves as a first step towards understanding their impacts and risks presented to higher trophic levels. Estuaries exist at the interface between freshwater and marine systems, and provide habitats for a diverse suite of species, including shellfish, fish, and birds. We provide baseline values for estuarine mudflats using sediment samples collected at Cowichan-Koksilah Estuary in British Columbia, Canada, a biologically-rich estuary. The estuary also contains a marine shipping terminal, forestry log sort area, and input of contaminants from nearby residential and agricultural areas. Microplastics, both fragments and fibers, occurred in 93% (13/14) of sediment samples. A mean of 6.8 microfibers/kg dw (range: 0–12 microfibers/kg dw) and 7.9 microfragments/kg (range: 0–19 fragments/kg dw) occurred in individual samples, and counts of fibers and fragments were strongly correlated (r = 0.78, p = 0.008, n = 14). The abundance of microplastics tended to be higher on the north side of the estuary that receives greater inputs from upland sources relative to the south side. Size distributions of microplastic fragments and fibers were similar to sediment grain size distribution with size categories 0.063 to 0.25 mm and 0.25 to 0.6 mm being the most common for plastics and sediment, indicating the occurrence of microplastics likely followed existing depositional processes within the estuary. Microplastics in sediments were composed of a variety of polymers, including high density polyethylene (HDPE), Nylon 6/6 (polyhexamethylene adipamide), and polyethylene terephthalate-PETE (poly(1,4-cyclohexylene dimethylene terephthalate)). This study indicates that microplastics occur throughout most of the Cowichan-Koksilah Estuary, and future studies should focus on the exposure risk and potential for bioaccumulation for wildlife species that feed on the surface of intertidal mudflats.

Effect of Nanoclay Addition on the Morphology, Fiber Size Distribution and Pore Size of Electrospun Polyvinylpyrrolidone (PVP) Composite Fibers for Air Filter Applications

The fabrication of Polyvinylpyrrolidone (PVP) electrospun layers for air filter applications is the target of this study. Solutions of 10% PVP containing 0, 3, 10 and 25 wt% nanoclay were used to fabricate electrospun fibers. Scanning electron microscopy showed that the fibers’ roughness increased by increasing the nanoclay content, and it was maximum at the nanoclay concentration of 25 wt%. Concurrently, nanoclay decreased the pore size considerably and increased the range of the fibers’ size distribution up to 100%. In addition, as the nanoclay concentration increased, the frequency distribution decreased abruptly for the larger fiber sizes and increased dramatically for the small fiber sizes. This phenomenon was correlated to the effect of nanoclay concentration on the conductivity of the solution. The solution’s conductivity increased from 1.7 ± 0.05 µS/cm for the PVP solution without nanoclay to 62.7 ± 0.19 µS/cm for the solution containing 25 wt% nanoclay and destabilized the electrospun jet, increasing the range of fiber size distribution. Therefore, the PVP solution containing 25 wt% nanoclay has potential characteristics suitable for air-filter applications, owing to its rougher fibers and combination of fine and thicker fibers.

Global Deletion of 11β-HSD1 Prevents Muscle Wasting Associated with Glucocorticoid Therapy in Polyarthritis.

Glucocorticoids provide indispensable anti-inflammatory therapies. However, metabolic adverse effects including muscle wasting restrict their use. The enzyme 11beta-hydroxysteroid dehydrogenase type 1 (11β-HSD1) modulates peripheral glucocorticoid responses through pre-receptor metabolism. This study investigates how 11β-HSD1 influences skeletal muscle responses to glucocorticoid therapy for chronic inflammation. We assessed human skeletal muscle biopsies from patients with rheumatoid arthritis and osteoarthritis for 11β-HSD1 activity ex vivo. Using the TNF-α-transgenic mouse model (TNF-tg) of chronic inflammation, we examined the effects of corticosterone treatment and 11β-HSD1 global knock-out (11βKO) on skeletal muscle, measuring anti-inflammatory gene expression, muscle weights, fiber size distribution, and catabolic pathways. Muscle 11β-HSD1 activity was elevated in patients with rheumatoid arthritis and correlated with inflammation markers. In murine skeletal muscle, glucocorticoid administration suppressed IL6 expression in TNF-tg mice but not in TNF-tg11βKO mice. TNF-tg mice exhibited reductions in muscle weight and fiber size with glucocorticoid therapy. In contrast, TNF-tg11βKO mice were protected against glucocorticoid-induced muscle atrophy. Glucocorticoid-mediated activation of catabolic mediators (FoxO1, Trim63) was also diminished in TNF-tg11βKO compared to TNF-tg mice. In summary, 11β-HSD1 knock-out prevents muscle atrophy associated with glucocorticoid therapy in a model of chronic inflammation. Targeting 11β-HSD1 may offer a strategy to refine the safety of glucocorticoids.

Preparation and characterization of electrospun cellulose acetate sub-micro fibrous membranes

Electrospun sub-microfiber membrane of cellulose acetate (CA), with excellent biodegradability, high specific surface area and high porosity, has attracted wide attention in various research fields. Even so, the stable continuous electrospinning of CA sub-micro fibers is affected by the solution parameters and CA acetylation degree dramatically, which still remains challenging. In the present work, electrospun CA sub-micro fibrous membranes have been prepared from four distinct solvent systems, respectively, to explore the proper solution parameters for membrane fabrication. After hydrolysis and electrospinning, the produced CA sub-micro fibrous membranes were analyzed in terms of fiber size distribution, hydrophilicity and porosity. Current analysis has shown that the degree of substitution of CA sub-micro fibers decreases with the increase in hydrolysis time, resulting in increased diameter irregularity, decreased average porosity and increased hydrophilicity of the sub-micro fibrous membrane.

Synthesis and Characterization of Electrospun Carbon Quantum Dots – Polyacrylonitrile/Polycaprolactone Composite Nanofiber Membranes for Copper (II) Adsorption

Heavy metal adsorption (HMA) is one of the remediation techniques used to remove heavy metals from water/wastewater. Composite membranes with functionalized additives for selective adsorption are being investigated. In this study, Carbon Quantum Dots – Polyacrylonitrile/Polycaprolactone nanocomposite membranes are synthesized by electrospinning which is intended for HMA of Cu2+. The nanofiber mats were characterized using SEM, FTIR, and Contact Angle. Batch adsorption process were performed and to utilize the AAS for kinetic adsorption behavior analysis. SEM micrographs revealed the addition of CQD in PAN and PAN/PCL membrane matrix shifted the fiber size distribution from 50 – 100 nm to 150 – 250 nm indicates the decrease in effective surface area. FTIR analysis exhibited vibrational peaks and binding of distinct functional groups such as amine, nitrile, carboxylic, hydroxyl, and carbonyl for CQD, PAN and PCL, respectively. CQD in aqueous form further increases the hydrophilicity of PAN/PCL membrane matrix which is essential for HMA of Cu2+ions. The increase of nanofiber mat’s adsorption capacity with respect to contact time obtained a maximum at 63.45 mg/g with a maximum efficiency of adsorption at 90.74%. Kinetic adsorption studies show that the pseudo – first order kinetic model best fits the data for CQD – PAN/PCL nanofiber mat in Cu2+ions obtaining a correlation value of R2= 0.9418 and a rate constant k = 0.0172 min1indicating the adsorption behavior follows the physical adsorption process involving Van der Waals forces and hydrogen bonding between the adsorbent and adsorbate.