Pore Size Diameter Research Articles

Probiotics mitigate thermal stress- and pathogen-driven impacts on coral skeleton

Threats leading to a reduction in coral populations are apparent worldwide. Several different approaches have been tested to accelerate the adaptation of corals to a changing climate. Here, we evaluated the skeleton structure, crystal habit, and chemical changes of the coral Pocillopora damicornis in response to the pathogen (Vibrio coralliilyticus) and probiotic (Beneficial Microorganisms for Corals, BMCs) inoculation under ambient conditions (26 °C) and thermal stress (30 °C) during a 50-day mesocosm experiment. The skeletons were analyzed using microtomography, energy-dispersive x-ray spectroscopy (EDX/SEM), and densitometry to investigate the skeleto-physico-chemical micro-morphological changes in porosity, median pore-size diameter, crystal habit, Mg/Ca, Sr/Ca, the skeleton mineral density (g/cm2) and skeleton mineral content (g–2). The results indicate considerable changes in the coral skeleton caused by both temperature and microbial inoculation. Most importantly, lower density (to ∼ x̄ 0.5 g/cm2) and higher porosity (up to ∼ x̄ 47%) were correlated with inoculation of V. coralliilyticus and mitigated by probiotics. BMCs also substantially increased calcification, as evidenced by Mg/Ca in the skeleton of thermally stressed corals. At the micron scale, aragonite crystal fibbers precipitated during the experiments showed an acicular habit in thermally stressed and pathogen-inoculated corals kept at 30 °C. In contrast, a spherulitic habit, characteristic of high growth rates, was observed in corals inoculated with both BMCs and V. coralliilyticus. Our findings reveal that pathogen inoculation and thermal stress had notable impacts on coral skeleton properties, including porosity, density, and crystal morphology, in a short period of time, which highlights the potential impacts of shifts in climate warming and environmental quality. Interestingly, BMCs played a role in maintaining the properties of skeleton calcification.

Adsorption of anionic dye from aqueous environment using surface-engineered Zn/Cu hydroxy double salt-based material: mechanistic, equilibrium and kinetic studies.

Herein, ethylene glycol (EG)-modified Zn/Cu hydroxy double salts (HDS) were synthesized using a facile synthetic approach. The formation of layered structure and presence of EG in the interlayer region were confirmed using PXRD and FTIR techniques. Furthermore, XPS analysis was used to confirm presence of metal ions in synthesized HDS. The surface area and pore size diameter of the HDS was found to be 32.30 m2 g-1 and 2.22 nm, respectively, using BET. The role of HDS was evaluated for its potential application as a sorbent for Congo red (CR) dye uptake. Batch studies were conducted to examine the impact of key variables, i.e., pH, time, adsorbent dosage and dye concentration on adsorption efficiency of HDS. Linear-nonlinear isotherm and kinetic models were employed for detailed analysis of experimental data. Langmuir, Freundlich and Temkin isotherm models were subsequently utilized to fit equilibrium data, among which Langmuir demonstrated to be most accurate. The maximum monolayer adsorption capacity estimated using Langmuir model was computed to be 181.81 mg g-1. The kinetic data follows pseudo-second-order model having good R2 value (0.999). Additionally, thermodynamic study suggested spontaneous and endothermic nature of adsorption process having reusability up to 5 cycles with removal efficiency more than 85%.

Tailored nanofibrous molecularly imprinted polymers for selective removal of di(2-ethylhexyl) phthalate: A computer-aided design and synthesis approach

This study aimed to develop molecularly imprinted polymer nanofibers (MIP-NFs) for the selective removal of di(2-ethylhexyl) phthalate (DEHP). Fifteen commonly used monomers were screened using computational calculations to determine the most suitable functional monomer for MIP-NFs synthesis. Methyl methacrylate (MMA) was selected based on its high binding energy (104.254 kJ mol−1) and strong hydrophobic interaction with DEHP in acetonitrile. The MIP-NFs were synthesized via a precipitation polymerization reaction using MMA as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the crosslinker, DEHP as the molecule template, and benzoyl peroxide (BPO) as the initiator. The resulting MIP-NFs exhibited a highly porous and fibrous structure with a larger surface area, pore volume, and pore diameter size compared to non-imprinted polymer nanofibers (NIP-NFs) and PAN-NFs. The Freundlich isotherm model was found to be the most suitable for describing the DEHP adsorption process by MIP-NFs, and the imprinting factor (IF) >1 indicated that MIP-NFs had a higher affinity for DEHP than NIP-NFs. The pseudo-second-order model better explained the adsorption process of MIP-NFs, and selectivity studies demonstrated that DEHP could selectively adsorb onto MIP-NFs. These results suggest that MIP-NFs have great potential in various applications such as water treatment and environmental remediation.

Multilayer 3D bioprinting and complex mechanical properties of alginate-gelatin mesostructures

In the biomedical field, extrusion-based 3D bioprinting has emerged as a promising technique to fabricate tissue replacements. However, a main challenge is to find suitable bioinks and reproducible procedures that ensure good printability and generate final printed constructs with high shape fidelity, similarity to the designed model, and controllable mechanical properties. In this study, our main goal is to 3D print multilayered structures from alginate-gelatin (AG) hydrogels and to quantify their complex mechanical properties with particular focus on the effects of the extrusion process and geometrical parameters, i.e. different mesostructures and macroporosities. We first introduce a procedure including a pre-cooling step and optimized printing parameters to control and improve the printability of AG hydrogels based on rheological tests and printability studies. Through this procedure, we significantly improve the printability and flow stability of AG hydrogels and successfully fabricate well-defined constructs similar to our design models. Our subsequent complex mechanical analyses highlight that the extrusion process and the mesostructure, characterized by pore size, layer height and filament diameter, significantly change the complex mechanical response of printed constructs. The presented approach and the corresponding results have important implications for future 3D bioprinting applications when aiming to produce replacements with good structural integrity and defined mechanical properties similar to the native tissue, especially in soft tissue engineering. The approach is also applicable to the printing of gelatin-based hydrogels with different accompanying materials, concentrations, or cells.

Removal of arsenic from contaminated water: Phytoaccumulation and adsorbent-based removal by activated carbon prepared from Typha tripholia

Aim: To assess the phytoaccumulation efficiency of arsenic in different parts of Typha tripholia (cattail) grown in the natural habitat of a pond located in Rada village of Bijua block, district Lakhimpur Kheri (U.P.) and to develop an adsorbent based removal technology by activated carbon prepared from Typha tripholia (ACTT) using physical activation. Methodology: Phytoaccumulation of arsenic was studied in cattail plants. Rhizomes and leaves of plants were used to prepare activated carbon. The morphological characterization and surface structure were studied by using different modern techniques like Scanning electron microscopy (SEM), Energy-dispersive X-ray (EDX), and Brunauer-Emmett- Teller (BET). The adsorption efficiency and removal of arsenic were studied by using different doses of ACTT, i.e., 0.5, 1.0, 1.5, 2.0, 2.5 g 100 m l-1 in the known solution of arsenate (30 ppb). Results: The arsenic concentration in pond water was 19 µg l-1, which was higher than the permissible limit (10 µg l-1) of WHO, while in the soil it was 123 µg kg-1. The maximum As concentration in the root was 360 µg kg-1, while in the stem and leaf, it was 20 µg kg-1 and 26 µg kg-1, respectively. Characteristics properties of ACTT showed amorphous nature and it contained 81.71 % carbon while other elements like oxygen (10.65 %), chloride (2.12 %) and potassium (5.52%) were also detected. The porosity of ACTT was 1.271 × 10-3 cc g-1 with pore volume 3.7 × 10-3 cc g-1, while the pore size, pore width, and pore diameter were 4.498 nm, 2.0208 nm and 4.498 nm, respectively. Removal of arsenic increased on increasing the dose of activated carbon, and the maximum adsorption (99.6%) was observed at 1.5 g 100-1 ml further it decreased. Interpretation: Thus, Typha tripholia may be used as phytoremediation, a plant-based green technology for the removal of As from contaminated water while ACTT acts as a good adsorbent for As, due to its large surface area and pore space and a high degree of surface reactivity. Key words: Arsenic removal, Activated carbon, Adsorption, Cattail, Phytoaccumulation

Surface investigations of selective biosorption and reduction of hexavalent chromium ions Cr(VI) over chitosan@MoO3 and chitosan-cellulose@MoO3 biocomposite.

Herein we synthesized two novel chitosan-based bicomposites namely chitosan@ MoO3 (Ch@MoO3) and chitosan-cellulose @ MoO3 (Ch-CS@MoO3) to detoxify water polluted with hexavalent chromium through adsorption reduction technology. The bicomposites were characterised using XPS, FT-IR, SEM, EDS, XRD, TGA, BET and DLS. XPS results suggested that Cr(VI) detoxification occurs through the electrostatic attraction and chemical bonding of Cr(VI) to the surface functional groups (Mo6+, -NH2+, -OH+) followed by reduction of Cr(VI) to Cr(III). FT-IR revealed changes in the surface functional groups after adsorption. XRD showed a successful incorporation of MoO3 into chitosan matrix. The surface texture of Ch@MoO3 was homogeneous with small spherical shape while Ch-CS@MoO3 exhibited a rough and dense fiber-like structure as evidenced by SEM characterization. N2 adsorption-desorption isotherm displayed H3-type hysteresis loop and a pore size diameter of 16.4 nm and 14.3 nm for the Ch@MoO3 & Ch-CS@MoO3 respectively. Adsorption capacity (Qmax) values were 128.2 and 52.3 mg/g for Ch@MoO3 and Ch-CS@MoO3 respectively. The metal surface coverage mapping was 5.4 × 1023 and 3.9 × 1020 atoms/m2 for Ch@MoO3 and Ch-CS@MoO3 respectively. Adsorption followed Langmuir isotherm and pseudo-second-order (PSO) kinetics, indicating monolayer chemisorption dominance. The intraparticle diffusion (IPD) model demonstrated a boundary layer control. Thermodynamically, both bicomposites exhibited spontaneous and endothermic biosorption nature.

Reinforcement of Injectable Hydrogel for Meniscus Tissue Engineering by Using Cellulose Nanofiber from Cassava Pulp.

Injectable hydrogels can be applied to treat damaged meniscus in minimally invasive conditions. Generally, injectable hydrogels can be prepared from various polymers such as polycaprolactone (PCL) and poly (N-isopropylacrylamide) (PNIPAAm). Poly (ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymer-diacrylate (PEO-PPO-PEO-DA) is an interesting polymer due to its biodegradability and can be prepared as water-insoluble injectable hydrogel after curing with UV light at low intensity. However, mechanical and cell adhesion properties are not optimal for these hydrogels. For the improved mechanical performance of the injectable hydrogel, cellulose nanofiber (CNF) extracted from cassava pulp was used as a reinforcing filler in this study. In addition, gelatin methacrylate (GelMA), the denatured form of collagen was used to enhance cell adhesion. PEO-PPO-PEO-DA/CNF/GelMA injectable hydrogels were prepared with 2-hydroxy-1-(4-(hydroxy ethoxy) phenyl)-2-methyl-1-propanone as a photoinitiator and then cured with UV light, 365 nm at 6 mW/cm2. Physicochemical characteristics of the hydrogels and hydrogels with CNF were studied in detail including morphology characterization, pore size diameter, porosity, mechanical properties, water uptake, and swelling. In addition, cell viability was also studied. CNF-reinforced injectable hydrogels were successfully prepared after curing with UV light within 10 min with a thickness of 2 mm. CNF significantly improved the mechanical characteristics of injectable hydrogels. The incorporation of GelMA into the injectable hydrogels improved the viability of human cartilage stem/progenitor cells. At optimum formulation, 12%PEO-PPO-PEO-DA/0.5%CNF/3%GelMA injectable hydrogels significantly promoted cell viability (>80%) and also showed good physicochemical properties, which met tissue engineering requirements. In summary, this work shows that these novel injectable hydrogels have the potential for meniscus tissue engineering.

Design and biomechanical analysis of patientspecific porous tantalum prostheses for knee joint revision surgery.

Artificial joint revision surgery, as an increasingly common surgery in orthopedics, often requires patient-specific prostheses to repair the bone defect. Porous tantalum is a good candidate due to its excellent abrasion and corrosion resistance and good osteointegration. Combination of 3D printing technology and numerical simulation is a promising strategy to design and prepare patient-specific porous prostheses. However, clinical design cases have rarely been reported, especially from the viewpoint of biomechanical matching with the patient's weight and motion and specific bone tissue. This work reports a clinical case on the design and mechanical analysis of 3D-printed porous tantalum prostheses for the knee revision of an 84-year-old male patient. Particularly, standard cylinders of 3D-printed porous tantalum with different pore size and wire diameters were first fabricated and their compressive mechanical properties were measured for following numerical simulation. Subsequently, patientspecific finite element models for the knee prosthesis and the tibia were constructed from the patient's computed tomography data. The maximum von Mises stress and displacement of the prostheses and tibia and the maximum compressive strain of the tibia were numerically simulated under two loading conditions by using finite element analysis software ABAQUS. Finally, by comparing the simulated data to the biomechanical requirements for the prosthesis and the tibia, a patient-specific porous tantalum knee joint prosthesis with a pore diameter of 600 μm and a wire diameter of 900 μm was determined. The Young's modulus (5719.32 ± 100.61 MPa) and yield strength (172.71 ± 1.67 MPa) of the prosthesis can produce both sufficient mechanical support and biomechanical stimulation to the tibia. This work provides a useful guidance for designing and evaluating a patient-specific porous tantalum prosthesis.

Activity and Selectivity of Mesoporous Silica Catalyst for Hydrocracking Process of Used Palm Oil into Biogasoline

Research on the synthesis of mesoporous silica catalyst, as well as its activity and selectivity in the hydrocracking of used palm oil, has been carried out. The research involved the preparation of mesoporous silica catalyst by varying the volume ratio of TEOS:CTAB at 2:1, 4:1, and 8:1, then calcined at 500 °C. Synthesis success was confirmed by FTIR, XRD, SEM-EDX, GSA, and hydrocracking selectivity by GC-MS analysis. The results showed that the more TEOS added, the silica bond composition, crystallinity, pore size, and product selectivity increased. The best catalyst performance was obtained from a TEOS:CTAB ratio of 8:1 at a calcination temperature of 500 °C (MCT81-500), which indicated the presence of Si-OH and Si-O-Si groups with a Si percentage of 45.31%, pore size diameter of 31.912 nm, and a total pore volume of 0.040 cc/g. In addition, the application of MCT81-500 in the hydrocracking process of used palm oil can produce a bio-gasoline (C5-C12) and kerosene (C12-C15) of 92.24 and 7.76 wt.%, respectively. This study shows that mesoporous silica has good potential for catalytic activity to convert used cooking oil waste into an environmentally friendly energy source.

Expanded hemodialysis: what's up, Doc?

In recent years there has been an increasing interest in expanded hemodialysis (HDx), an emerging renal replacement therapy based on the use of medium cut-off membranes (MCO). Thanks to the internal architecture of these types of membranes, with a higher pore size and smaller fiber inner diameter to favor internal filtration rate, they can increase the removal of larger middle molecules in conventional hemodialysis. Secondarily, several reports suggest that this therapy potentially improve the outcomes for end-stage renal disease patients. However, HDx has not been defined yet and the characteristics of MCO membranes are not well stablished. The aim of this narrative review is to define HDx and summarize the dialyzers that have been used so far to perform this therapy, collect the evidence available on its efficacy and clinical outcomes compared with other hemodialysis techniques and settle the bases for its optimal prescription.

Nanoclay-Incorporated Polycaprolactone Matrix via Electrospinning Techniques-Enriched Spectroscopic Responses

Nanotechnology is one of the most common areas for current research and development in almost all technological fields. A significant factor is the synergistic benefit of nanoscale dimensions over larger scale alteration. Polymer nanoscience is the analysis and application of nanotechnology to polymer nanoparticle matrices, with nanoparticles described as those with at least one dimension of less than 100 nm. The use of polymer nanotechnology and nanocomposites in practical applications is a rapidly developing area. For making polymeric nanofibers from polymer melts and solutions, a spinning technique is used known as electrospinning. Electrospinning is an easy way to produce ultrafine fibers, which is nanosize. For its wide range of variety of spinning polymeric fibers, it is recommended, as well as producing fibers in nanosize accurately. The aim of this project is to use electrospinning to make nanoclay integrated polycaprolactone membranes. The effects of the nanoclay on morphology, thermal, and sorption behaviors of the electrospun membrane were further studied. The scope of this project work is that the electrospun nanocomposites are best studied for biomedical applications. Because of their influence over porosity, pore size, and fiber diameter, they make excellent scaffold materials.

The synthesis, characterizations, and lead adsorption studies of chicken eggshell powder and chicken eggshell powder-doped iron (III) oxide-hydroxide

The contamination of lead in wastewater causes water quality problems, which is toxic to aquatic organisms and environment, so wastewater treatment is required before discharging to receiving water. Chicken eggshell powder (CP) and chicken eggshell powder-doped iron (III) oxide-hydroxide (CPF) were synthesized, characterized, and investigated lead removal efficiencies by batch experiments, adsorption isotherms, kinetics, and desorption experiments. The specific surface area and pore volume of CPF were higher than CP, whereas the pore diameter size of CPF was smaller than CP. The phase structures of both materials demonstrated semi-crystalline phases with presenting peaks of calcium carbonate. Their surface morphologies were irregular, rough, and uneven surfaces. In both materials, they detected carbon, calcium, oxygen, OH, NH, CO, CO, and CH. The point of zero charges (pHpzc) of CP and CPF were 4.47 and 4.83. For batch experiments, CPF demonstrated a higher lead removal efficiency than CP because of spending less material dosage and contact time than CP, and both materials had high lead removals at a lead concentration of 50 mg/L by more than 95 %. Thus, the addition of iron (III) oxide-hydroxide helped to increase material efficiency for lead adsorption. CP corresponded to the Langmuir model while CPF corresponded to the Freundlich model. In addition, both materials corresponded to a pseudo-second-order kinetic model relating to a chemisorption process. Moreover, both materials could be reusable for more than 5 cycles for lead adsorption of more than 77 %. Therefore, CPF was a potential material to apply for lead removals in industrial applications.

Effect of incorporating hydrophilic silica on carbon dioxide volumetric mass transfer coefficient using a fabricated membrane as the diffuser

In this work, 0 %,1.5 wt%, and 3 wt%, of the hydrophilic silica loading were prepared respectively (later denoted as N-0, N-1.5 and N-3), and their effect on the membrane surface properties, equivalent bubble diameter, and volumetric CO2 mass transfer coefficient (kLa) were investigated at a different flow rate (0.05 – 20 ml/s). The results show a slight decrease in pore size diameter of N-3, and N-1.5 without significant change in contact angle. At a low flow rate of 0.1 ml/s the bubble size of N-3 decreased by 50 %, which led to an increase of 143 % in the kLa compared to N-0.

Advanced oxidation processes in the treatment of corn stalks

The depletion of fossil fuel reserves and severe environmental damage, resulting in climate change and global warming lead to a necessary shift to alternative renewable resources. Lignocellulose is a valuable feedstock for biorefineries, but its conversion is hindered by the limitations of conventional pretreatments lacking selectivity. This step should also be cost-effective and sustainable. In this paper, combined advanced oxidation techniques were applied for the treatment of corn stalks as a pretreatment for enzymatic hydrolysis. Their effect on delignification and cellulose digestibility was monitored. The combined non-thermal plasma/Fenton treatment appears to be suitable for breaking the complex lignocellulose structure, with a lignin content decrease of 39%. This treatment enhanced carbohydrate hydrolysis, resulting in 2.25 times increase in hexose yield, compared to the untreated sample. Long-term plasma treatment positively affected the textural properties, total porosity, and pore size diameter, of lignocellulose biomass. It enables the creation of materials with a stable system of pores and channels, for the unhindered diffusion of large organic molecules such as enzymes. Additionally, a combination of plasma treatment with Fenton reaction increased selectivity towards lignin degradation in comparison to independently applied Fenton treatment. This could be a significant advantage for a bottleneck in the current valorization of biomass.

Novel preparation of metal-free carbon xerogels under acidic conditions and their performance as high-energy density supercapacitor electrodes.

The development of metal-free supercapacitor electrodes with a high energy density is a crucial requirement in the global shift towards sustainable energy sources and industrial pursuit of an optimal supercapacitor. Indeed, from an industrial perspective, time assumes a paramount role in the manufacturing process. A majority of synthesis methods employed for the fabrication of carbon xerogel-based supercapacitor electrodes are characterized by prolonged durations, and result in relatively poor energy and power density. These limitations hinder their practical applications and impede their widespread manufacturing capabilities. In this study, carbon xerogel-based supercapacitor electrodes were made in the shortest time ever reported by making the condition highly acidic with hydrochloric acid (HCl). Furthermore, the investigation of the effect of HCl concentrations (0.1 M, 0.05 M, and 0.01 M) on the morphology and electrochemical behavior of the prepared samples is reported herein. Interestingly, the highest concentration of HCl developed the highest BET surface area, 1032 m2 g-1, which enforced the capacitive behavior to deliver a specific capacitance of 402 F g-1 at 1 A g-1 and a capacitance retention of 80.8% at a current density of 2 A g-1 in an electrolyte containing 0.5 M H2SO4 + 0.5 M Na2SO4. Moreover, an impressive energy density of 45 W h kg-1 at a power density of 18.2 kW kg-1 was achieved. Interestingly, as the HCl concentration increased, the equivalent series resistance decreased to 3.9 W with carbon xerogel 0.1 M HCl (CX0.1). The superior performance of CX0.1 may be attributed to its enlarged BET surface area, pore volume, pore diameter, and smaller particle size. This work provides a facile approach for the large-scale production of metal-free carbon supercapacitor electrodes with improved performance and stability and opens novel horizons to explore the impacts of many types of catalysts during the carbon xerogel preparation.

Textural Properties Characterization for NaX and FeX Zeolites by Nitrogen Adsorption-desorption Technique

The zeolite's textural properties have a significant effect on zeolite's effectiveness in the different industrial processes. This research aimed to study the textual properties of the NaX and FeX zeolites using the nitrogen adsorption-desorption technique at a constant low temperature. According to the International Union of Pure and Applied Chemistry, the adsorption-desorption isotherm showed that the studied materials were mixed kinds I/II isotherms and H3 type hysteresis. The Brunauer-Emmett-Teller isotherm was the best model to describe the nitrogen adsorption-desorption better than the Langmuir and Freundlich isotherms. The obtained adsorption capacity and Brunauer-Emmett-Teller surface area values for NaX were greater than FeX. According to the Kelvin equation, Barrett, Joyner, and Halenda model was used to determine pore size distribution, diameter, and average pore volume for the selected zeolites. The pore size distribution for NaX was wider than FeX zeolites, the pore diameter for NaX was less than FeX, and the average pore volume for FeX was greater than the value of NaX average pore volume. The comparative study was carried out with the previous studies, and the comparison showed that the textual properties of the modified zeolites agreed with other studies.

Preparation of mesoporous carbon with adjustable diameter and pore size

Mesoporous carbon (MC) has attracted extensive scientific and technological interest due to its fascinating and excellent properties. However, it remains a great challenge to synthesize MC materials with adjustable pore diameter and particle size, well-designed functionalities, uniform morphology, relatively high graphitization, and good repeatability. Herein, using mesoporous silicon (SiO2) as a template, we fabricated a locally ordered MC material with controllable pore size by the nanocasting strategy. The carbon material exhibited a large specific surface area (~979 m2/g), relative high graphitization degree, adjustable pore size (2.85–5.79 nm), and particle diameter (79–194 nm). Different experimental conditions were regulated; the organic molecules (cetyltrimethylammonium bromide) played an important role in the change of particle diameter, while the hydrothermal reaction time accurately controlled the pore size. This simple preparation approach simultaneously realized the independent design of the carbon structure and graphitization degree, which is conducive to the subsequent doping modification of carbon materials.

Synergistic effect of cerium and structure directing agent on drug release behavior and kinetics

This work was mainly aimed at the study of the dual effect of cerium and structure directing agent template concentration, on vancomycin release profiles and kinetics from Ce-substituted mesoporous bioactive glasses (MBGs). MBG based on (20-x) B2O3 - 55 SiO2 – 20 CaO – 5 P2O5 – x Ce2O (x = 0, 1 and 3 mol %) was synthesized by the evaporation-induced self-assembly process using two molar ratios (0.01 and 0.02 molar ratio) of nonionic block copolymer Pluronic® 123 (P123) surfactant. The TGA-DTA, FTIR, and textural features analyses were carried out for the glasses. Moreover, the in vitro bone-forming activity and degradation analysis were tested using simulated body fluid (SBF). The drug loading capacity, drug release profile, and kinetics (using different kinetic models such as first order, Higuchi, Hixson-Crowell, and Baker-Lonsdale models) were determined using vancomycin as a drug model. The results showed that the isotherms of all MBGs fit with type IV isotherms, and the surface area of MBGs synthesized by 0.02 M template was higher than that prepared by 0.01 M, where it ranged from 174.05 m2.g−1 to 256.73 m2.g−1. The pore size diameter was decreased as cerium content increased in all MBGs (decreased from 5.44 to 3.54 nm). Moreover, the MBGs induced the formation of a bone-like apatite layer, and their biodegradation properties can be tailored by controlling glass composition. Furthermore, Ce-free MBGs showed the lowest drug adsorption and the highest drug release percentage. The drug release kinetic was best fitted with Higuchi and Baker-Lonsdale models which denoted that the mechanism of drug release from MBGs was a diffusion release from spherical particles. In conclusion, vancomycin release was controlled by the glass composition. Meanwhile, the MBGs synthesized in this study are proposed to be applied for bone regeneration, bone cancer treatment, and reducing the bacterial activity around the tumor site.Graphical abstract

Hollow TiO2/Poly (Vinyl Pyrrolidone) Fibers Obtained via Coaxial Electrospinning as Easy-to-Handle Photocatalysts for Effective Nitrogen Oxide Removal.

Herein, we present a method for fabricating hollow TiO2 microfibers from Ti (OBu)4/poly (vinyl pyrrolidone) sol-gel precursors and their effects on denitrification as a photocatalyst for air purification. Various sizes of hollow TiO2 fibers were developed using coaxial electrospinning by controlling the core flow rate from 0 to 3 mL h-1. At higher flow rates, the wall layer was thinner, and outer and core diameters were larger. These features are correlated with physical properties, including specific surface area, average pore diameter, and crystalline structure. The increase in the core flow rate from 0 to 3 mL h-1 leads to a corresponding increase in the specific surface area from 1.81 to 3.95 µm and a decrease in the average pore diameter from 28.9 to 11.1 nm. Furthermore, the increased core flow rate results in a high anatase and rutile phase content in the structure. Herein, hollow TiO2 was produced with an approximately equal content of anatase/rutile phases with few impurities. A flow rate of 3 mL h-1 resulted in the highest specific surface area of 51.28 m2 g-1 and smallest pore diameter size of ~11 nm, offering more active sites at the fiber surface for nitrogen oxide removal of up to 66.2% from the atmosphere.

Structure sensitivity of propane partial oxidation over chromium-manganese binary oxides

Catalytically active chromium-manganese oxides (CMO) were synthesized by the sol-gel route for the partial oxidation of propane to propene. The effects of calcination temperature and time on the catalytic performance of the CMO were examined in a fixed bed reactor within 300–600 °C at a gas hourly space velocity (GHSV) of 6,000 mL·g−1cat·h−1. Structural and morphological analysis disclosed nano-crystallite sizes and spherical shapes with smooth and tiny particles. The introduction of Cr tends to increase the specific surface area, decrease the pore diameter and crystallite size, as well as the bandgap energy of the obtained samples, which promoted the movement of abundant lattice oxygen. Based on the light-off curves, the catalyst CM32 (CMO calcined at 300 °C@2 h), with low calcination temperature and long calcination time, achieved the best performance and stability. CM32 exhibited the highest selectivity and yield, 79.35% and 29.80%, respectively. CM32 owned a reaction rate of 2.93 mol·g−1cat·s-1 and apparent activation energy of 49.52 kJ mol-1, which could be related to not only its higher quantity of lattice oxygen (O2−) and Cr6+/Cr3+ ratio, but also to the decrement in pore diameter size and bandgap energy. The reaction pathway was proposed based on the MvK mechanism for the propane partial oxidation. Moreover, CM32 maintained its catalytic performance after a stability test of 100 h’ time-on-stream. The highly stable and active CM32 catalyst obtained shows good potential for partial oxidation of propane to propene.