The equilibrium moisture content (EMC) of raw lignocellulosic biomass, along with four samples subjected to thermal pretreatment, was measured at relative humidities ranging from 11% to 97% at a ...constant temperature of 30°C. Three samples were prepared by treatment in hot compressed water by a process known as wet torrefaction, at temperatures of 200, 230, and 260°C. An additional sample was prepared by dry torrefaction at 300°C. Pretreated biomass shows EMC below that of raw biomass. This indicates that pretreated biomass, both dry and wet torrefied, is more hydrophobic than raw biomass. The EMC results were correlated with a recent model that takes into account additional non-adsorption interactions of water, such as mixing and swelling. The model offers physical insight into the water activity in lignocellulosic biomass.
As a renewable non-food resource, lignocellulosic biomass has great potential as an energy source or feedstock for further conversion. However, challenges exist with supply logistics of this ...geographically scattered and perishable resource. Hydrothermal carbonization treats any kind of biomass in 200 to 260
°C compressed water under an inert atmosphere to produce a hydrophobic solid of reduced mass and increased fuel value. A maximum in higher heating value (HHV) was found when 0.4
g of acetic acid was added per g of biomass. If 1
g of LiCl and 0.4
g of acetic acid were added per g of biomass to the initial reaction solution, a 30% increase in HHV was found compared to the pretreatment with no additives, along with greater mass reduction. LiCl addition also reduces reaction pressure. Addition of acetic acid and/or LiCl to hydrothermal carbonization each contribute to increased HHV and reduced mass yield of the solid product.
Composites made of zeolites with silver (Ag) and high molecular weight chitosan matrices were synthesized using a solvent-casting technique. XRD, ED-XRF, and FTIR results revealed the successful ...inclusion of Ag into the natural zeolite. Results also showed the possible redistribution of the exchangeable cations within the zeolite framework after the ion-exchange process. Plasma treatment modified the surface properties of the composites as revealed by AFM and surface free energy (SFE) calculations. Roughness increased with increasing Ag-zeolite content and increased further by at least 2.3 times after plasma exposure. Water contact angle decreased by half after treatment. SFE increased by at least 25% due to the increased contribution of the polar component after plasma treatment. This work showed that the ion-exchange method is effective in incorporating Ag into the zeolite framework and plasma treatment can tune the surface properties such as roughness and wettability. With the promising properties of the composites attributed to the biocompatibility of chitosan and zeolite, the antibacterial activity of Ag and the improved surface characteristics due to plasma treatment, the material is a suitable candidate for biomedical applications.
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•29.3 wt% silver was incorporated into the zeolite framework via ion exchange process.•Silver-exchanged-zeolite-chitosan composite was successfully fabricated.•Roughness increased with higher AgZ content and doubled after plasma exposure.•Surface energy is mostly dispersive; plasma treatment increased the polar component.
Pernio after COVID‐19 vaccination Lopez, S.; Vakharia, P.; Vandergriff, T. ...
British journal of dermatology (1951),
August 2021, Letnik:
185, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Dear Editor: Pernio-like acral lesions are a common dermatologic manifestation reported after SARS-CoV-2 (COVID-19) infection
. The pernio-like eruption characteristically seen on the feet has been ...coined "COVID toes". These lesions are more often seen in mild to asymptomatic patients and represent a late manifestation of COVID-19 infection
. Here, we present a case of pernio that appeared after the Pfizer BNT162b1 COVID-19 vaccine, in an asymptomatic patient with negative polymerase chain reaction (PCR) testing.
The use of materials to restore or replace the functions of damaged body parts has been proven historically. Any material can be considered as a biomaterial as long as it performs its biological ...function and does not cause adverse effects to the host. With the increasing demands for biofunctionality, biomaterials nowadays may not only encompass inertness but also specialized utility towards the target biological application. A hydrogel is a biomaterial with a 3D network made of hydrophilic polymers. It is regarded as one of the earliest biomaterials developed for human use. The preparation of hydrogel is often attributed to the polymerization of monomers or crosslinking of hydrophilic polymers to achieve the desired ability to hold large amounts of aqueous solvents and biological fluids. The generation of hydrogels, however, is shifting towards developing hydrogels through the aid of enabling technologies. This review provides the evolution of hydrogels and the different approaches considered for hydrogel preparation. Further, this review presents the plasma process as an enabling technology for tailoring hydrogel properties. The mechanism of plasma-assisted treatment during hydrogel synthesis and the current use of the plasma-treated hydrogels are also discussed.
The influence of plasma-forming gases such as argon and oxygen in the reduction of silver ions (
Ag
+
) infused into a natural zeolite framework has been investigated for antibacterial applications. ...Impregnation by soaking and ion exchange were combined with 13.56 MHz radio-frequency plasma to reduce
Ag
+
to their metallic state for a greener and energy-efficient process. The plasma treatment of the silver zeolite (AgZ) composites did not alter the crystalline structure of the zeolite, while successfully reducing
Ag
+
to its metallic form as a nanoparticle encapsulated by the zeolite. The antibacterial index of the AgZ composites against
Staphylococcus aureus
and
Escherichia coli
confirmed the fervent antibacterial activity of plasma-reduced Ag NP embedded in the zeolite matrix against the two bacterial strains. The highest activity belongs to the samples treated with oxygen plasma. This result is related to increased active area of contact and the incorporation of reactive oxygen species in the zeolite matrix, which contributed to the antibacterial sensitivity of the plasma-treated AgZ.
Objective: This study investigated the remineralization potential of theobromine in comparison to a standard NaF dentifrice. Methods: Three tooth blocks were produced from each of 30 teeth. ...Caries-like lesion was created on each block using acidified gel. A smaller block was cut from each block for baseline scanning electron microscopy imaging and electron-dispersive spectroscopy (EDS) analysis for surface Ca level. A tooth slice was cut from each lesion-bearing block for transverse microradiography (TMR) quantification of baseline mineral loss (Δz) and lesion depth (LD). Then baseline surface microhardness (SMH) of each lesion was measured. The three blocks from each tooth were assigned to three remineralizing agents: (1) artificial saliva; (2) artificial saliva with theobromine (0.0011 mol/l), and (3) NaF toothpaste slurry (0.0789 mol/l F). Remineralization was conducted using a pH cycling model with storage in artificial saliva. After a 28-day cycle, samples were analyzed using EDS, TMR, and SMH. Intragroup comparison of pre- and posttest data was performed using t tests (p < 0.05). Intergroup comparisons were performed by post hoc multistep comparisons (Tukey). Results: SMH indicated significant (p < 0.01) remineralization only with theobromine (38 ± 32%) and toothpaste (29 ± 16%). With TMR (Δz/lD), theobromine and toothpaste exhibited significantly (p < 0.01) higher mineral gain relative to artificial saliva. With SMH and TMR, remineralization produced by theobromine and toothpaste was not significantly different. With EDS, calcium deposition was significant in all groups, but not significantly different among the groups (theobromine 13 ± 8%, toothpaste 10 ± 5%, and artificial saliva 6 ± 8%). Conclusion: The present study demonstrated that theobromine in an apatite-forming medium can enhance the remineralization potential of the medium.
Despite advances in cancer treatment, breast cancer remains the second foremost cause of cancer mortality among women, with a high rate of relapse after initial treatment success. A subpopulation of ...highly malignant cancer cells, known as cancer stem cells (CSCs), is suspected to be linked to metastasis and relapse. Targeting of CSCs may therefore provide a means of addressing cancer-related mortality. However, due to their low population in vivo and a lack of proper culture platform for their propagation, much of the CSC biology remains unknown. Since maintenance of CSCs is heavily influenced by the tumor microenvironment, this study developed a 3D culture platform that mimics the metastatic tumor extracellular matrix (ECM) to effectively increase CSC population in vitro and allow CSC analysis. Through electrospinning, nanofibers that were aligned, porous, and collagen-coated were fabricated from polycaprolactone to recreate the metastatic tumor ECM assemblage. Breast cancer cells seeded onto the nanofiber scaffolds exhibited gross morphology and cytoskeletal phenotype similar to invasive cancer cells. Moreover, the population of breast cancer stem cells increased in nanofiber scaffolds. Analysis of breast cancer cells grown on the nanofiber scaffolds demonstrated an upregulation of mesenchymal markers and an increase in cell invasiveness suggesting the cells have undergone epithelial-mesenchymal transition. These results indicate that the fabricated nanofiber scaffolds effectively mimicked the tumor microenvironment that maintains the cancer stem cell population, offering a platform to enrich and analyze CSCs in vitro.
This paper presents a neural network-based classifier to predict whether a person is at risk of developing chronic kidney disease (CKD). The model is trained with the demographic data and medical ...care information of two population groups: on the one hand, people diagnosed with CKD in Colombia during 2018, and on the other, a sample of people without a diagnosis of this disease. Once the model is trained and evaluation metrics for classification algorithms are applied, the model achieves 95% accuracy in the test data set, making its application for disease prognosis feasible. However, despite the demonstrated efficiency of the neural networks to predict CKD, this machine-learning paradigm is opaque to the expert regarding the explanation of the outcome. Current research on eXplainable AI proposes the use of twin systems, where a black-box machine-learning method is complemented by another white-box method that provides explanations about the predicted values. Case-Based Reasoning (CBR) has proved to be an ideal complement as this paradigm is able to find explanatory cases for an explanation-by-example justification of a neural network's prediction. In this paper, we apply and validate a NN-CBR twin system for the explanation of CKD predictions. As a result of this research, 3,494,516 people were identified as being at risk of developing CKD in Colombia, or 7% of the total population.
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•AgZ-Ch composites exhibited antibacterial activity due to the presence of AgZ.•Plasma treatment improved wettability and surface adhesion of AgZ-Ch composites.•AgZ-Ch composites ...possess cytocompatible and blood clotting abilities.•Pristine AgZ-Ch composites have wound healing applications potential.•Plasma-treated AgZ-Ch composites have potential as tissue scaffolds.
Silver-exchanged zeolite-chitosan (AgZ-Ch) composites with varying AgZ content were prepared by solvent casting and modified under argon (Ar) plasma excited by a 13.56MHz radio frequency (RF) power source. Silver (Ag) was successfully incorporated in a natural zeolite host without losing its antibacterial activity against Escherichia coli and Staphylococcus aureus. The AgZ particles were incorporated into a chitosan matrix without making significant changes in the matrix structure. The composites also exhibited antibacterial sensitivity due to the inclusion of AgZ. Plasma treatment enhanced the surface wettability of polar and nonpolar test liquids of the composites. The average increase in total surface free energy after treatment was around 49% with the polar component having a significant change. Cytocompatibility tests showed at least 87% cell viability for pristine and plasma-treated composites comparable with supplemented RPMI as positive control. Hemocompatibility tests revealed that pristine composites does not promote hemolysis and the blood clotting ability is less than 10min. Coupled with antibacterial property, the fabricated composites have promising biomedical applications.
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