Rod-shaped Particles Research Articles

Precipitation behaviour of simulated high-level liquid waste during the denitration process based on two-step vitrification

In the two-step vitrification process, it is necessary to first reduce the acidity of the waste before calcination. In this study, the influence of formic acid as a denitration agent on the precipitation behavior of a simulated high-level liquid waste during denitration was investigated. The denitration process was conducted at a temperature of 90℃, and the denitration ratio ranged from 1.0 to 2.0. The denitration products were analyzed using various techniques including ICP-OES, XRF, SEM-EDS, Raman, and XRD. The results revealed a significant decrease in nitrate content after denitration when the denitration ratio was between 1.0 and 2.0. As the denitration ratio increased, the nitrate content progressively decreased, while the formic acid content increased. A denitration precipitate containing elements such as Zr, Mo, La, Ce, Nd, Fe, Te, Pr, Cs, Sm, Sr, Y, Co, and Ni was observed. The content of each component and the morphology of the precipitate were found to be correlated with the denitration ratio. Crystallization of MoO2 and Ln2Zr3(MoO4)9 (Ln = La, Ce, Nd, Pr, Sm) in the precipitation occurred when the denitration ratio was between 1.0 and 1.2. On the other hand, predominantly rod-shaped particles (Ln(HCOO)3, Ln = La, Ce, Pr, Nd, Sm) were formed when the denitration ratio was 1.4 or higher.

Sorafenib tosylate-loaded nanosuspension: preparation, optimization, and in vitro cytotoxicity study against human HepG2 carcinoma cells

This study aimed to optimize nanosuspension of sorafenib tosylate (an anticancer hydrophobic drug molecule) using a central composite design. Nanosuspension was prepared using a nanoprecipitation-ultrasonication approach. FTIR and DSC analyses demonstrated that the drug and excipients were physicochemically compatible. X-ray powder diffraction analysis confirmed amorphous form of the payload in the formulation. The optimized formulation (batch NSS6) had a zeta potential of −18.1 mV, a polydispersity of 0.302, and a particle size of 97.11 nm. SEM analysis confirmed formation of rod-shaped particles. After 24 h, about 64.45% and 86.37% of the sorafenib tosylate was released in pH 6.8 and pH 1.2, respectively. The MTT assay was performed on HepG2 cell lines. IC50 value of the optimized batch was 39.4 µg/mL. The study concluded that sorafenib tosylate nanosuspension could be a promising approach in the treatment of hepatocellular cancer.

Chitosan coated copper/silver oxide nanoparticles as carriers of breast anticancer drug: Cyclin D1/P53 expressions and cytotoxicity studies

Developing new treatment strategies for cancer is necessary and inevitable. The aim of this study is the synthesis of a novel nanocomposite (NC) based on chitosan coated copper/silver oxide nanoparticles ((CuO-Ag2O-NCs) ant evaluation of its effect on breast cancer and cyclin D1/P53 expression. A thermal process (500 °C) was used for synthesis of NCs. Characterization was done by powder X-ray Diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR) and field emission electron microscopy (FESEM). The prepared CuO-Ag2O-NCs were also tested against breast cancer cells (MCF-7) and Human foreskin fibroblasts (HFF) cell lines. Also, the expression ofCylclin D1 andP53 genes was measured in MCF-7 cells under CuO-Ag2O-NCs treatment. The XRD showed both CuO and Ag2O phases without no purity or negligible contaminants. The FTIR spectrum also confirmed proper synthesis (peaks at 485, 531and 579 cm−1: CuO vibrations, 721 and 1440 cm−1: Ag2O). FESEM images demonstrated polymorphic particles in which rod-shaped particles were the distinguished ones. Anticancer test indicated significant inhibitory effect of nanoparticle on the growth of MCF-7 cells in a dose-dependent manner. The viability evaluation of MCF-7 cells demonstrated an IC50 value of 173.9, 30.11 and 5.462 µg/mL at 24, 48 and 72 h after treatment, respectively. Prepared NCs had lower toxicity on HFF cell lines in comparison with MCF-7 cells. The results showed that bothcyclin D1andP53expressions enhanced after 48 h of incubation. Results showed that the CuO-Ag2O-NCs induced apoptosis cancer cells compared to control cells. According to results, acquired nanostructures had potent anticancer activity via change in gene expression and apoptosis induction.

Silver molybdate nanocrystal-reinforced high-performance anti-coronavirus composite polymer coating

In response to the present epidemic situation, this work proposes an anti-coronavirus composite polymer coating with nano-Ag2MoO4 as the core component to reduce the potential safety hazards caused by excessive use of disinfectants. Nano-β-Ag2MoO4 with mixed morphology was produced with industrialized preparation technology. Among them, oval nanoparticles are core components with antiviral properties, and long rod-shaped particles are used to identify whether the stirring process meets the standard. After x-ray diffraction and field emission scanning electron microscopy testing, nano-β-Ag2MoO4 stored for 4 years still meets the design requirements in terms of purity, crystal phase, shape, and scale, which solves the problem of the long-term effect of core components. In the existing water-based paint production process, the mixing process and formula of nano-β-Ag2MoO4 were explored, and the large-scale production process of anti-virus water-based paint was solved. Resistance tests against the HCoV-229E coronavirus showed that the anti-coronavirus activity rate of the nano-β-Ag2MoO4 coating at a weight concentration of 200 ppm was 99.5% within 2 h, which verified the effectiveness of the composite polymer coating.

Molecular and Biological Characterization of a Novel Tobamovirus Infecting Sunn Hemp (Crotalaria juncea) in Hawaii.

Sunn hemp (Crotalaria juncea L.) cultivar Tropic Sun plants, stunted and displaying mottle and mosaic symptoms on foliage, were observed at a seed farm in Maui County, Hawaii. Lateral flow assays indicated the presence of either tobacco mosaic virus or a serologically related virus. High-throughput sequencing results coupled with real-time PCR experiments recovered the 6,455-nucleotide genome of a virus with an organization typical of tobamoviruses. Nucleotide and amino acid sequence comparisons and phylogenetic analyses indicated that this virus was most closely related to sunn-hemp mosaic virus but represents a distinct species. Sunn-hemp mottle virus (SHMoV) is being proposed as the common name of this virus. Transmission electron microscopy of virus extracts purified from symptomatic leaves revealed rod-shaped particles approximately 320 by 22 nm in size. In inoculation studies, the experimental host range of SHMoV appeared limited to members of the plant families Fabaceae and Solanaceae. Greenhouse experiments demonstrated plant-to-plant transmission of SHMoV that increased with ambient wind speed. Seeds from SHMoV-infected Tropic Sun were collected and were either surface disinfested or directly planted. A total of 924 seedlings germinated; 2 were positive for the virus, resulting in a seed transmission rate of 0.2%. Both infected plants came from the surface disinfestation treatment, suggesting that the virus might be unaffected by the treatment.

Phase Field Simulation of the Effect of Second Phase Particles with Different Orientations on the Microstructure of Magnesium Alloys.

In this study, the phase field method has been used to study the effect of second phase particles with different shapes and different orientations on the grain growth of AZ31 magnesium alloy, after annealing at 350 °C for 100 min. The results show that the shape of the second phase particles would have an effect on the grain growth; the refinement effect of elliptical particles and rod-shaped particles was similar, and better than the spherical particles; the spatial arrangement direction of the second phase particles had no significant effect on the grain growth. On the other hand, when the microstructure of AZ31 magnesium alloy contained second phase particles with different shapes, the effect of mixing different shapes of second phase particles on the grain refinement was enhanced gradually with the decrease im the volume fraction of spherical particles.

SiO2–CaO rod-like particles in chitosan matrix as bioactive coatings for stainless steel implants

Metals have outstanding mechanical properties, being capable of supporting the combined stresses applied to biomaterials (e.g. orthopaedic implants) by the human body. Metals can be biocompatible (such as Ti or stainless steel) but they are bioinert, they generally do not generate a natural bonding with bone tissue, and it is then necessary to produce a kind of anchor or external fixation to improve the implant-bone interface. The surface chemistry and morphology of stainless steel, a material widely used for orthopaedic implants, can affect the interaction of the implant with the surrounding medium and cell attachment and growth, thus affecting the compatibility between the host tissue and the material. The aim of this work is to enhance the bioactivity of stainless steel implants by the application of a combined coating of chitosan and bioactive silica-calcia (SiCa) rod-shaped particles. Stainless steel substrates were coated in two different concentrations of SiCa particles produced by the Stöber method, immersed in a chitosan matrix via electrophoretic deposition. Thick and homogeneous coatings were achieved following the optimization of the deposition parameters, with average thicknesses between 12 and 19 μm. Although the coating exhibited fast rates of dissolution, the formation of carbonated calcium phosphate could be observed after immersion for 10 days in simulated body fluid (SBF), in microscopic images, which was confirmed via spectroscopic analysis. Murine stromal ST-2 cell proliferation was found after 4 and 10 days of seeding, indicating that the coating was not toxic and able to sustain the adhesion and growth of ST-2 cells.

Study of supersaturated solid solution decomposition during quenching of sheets from Al-Mg-Si aluminum alloy

This paper presents the results of a study of the stability of a supersaturated solid solution (SSS) of sheets made of thermally hardened aluminum alloy of the Al-Mg-Si system with a small addition of copper (Al-0.6Mg-1.0Si-0.2Cu) under various quenching modes. The samples were subjected to isothermal or continuous quenching with different quenching cooling rates, after which artificial aging was carried out at a temperature of 170°C. From the results of thermodynamic modeling of the equilibrium phase composition of the alloy, it was found that for the temperature range from 300 to 530°C, the presence of the β-phase (Mg2Si) is most likely. With the use of transmission electron microscopy and X-ray spectral microanalysis, it was found that during quenching, the decomposition of SSS leads to the precipitation of undesirable large particles of metastable β-type phases or equilibrium β-phase. The nucleation of the secretions is realized in the form of rod-shaped particles by a heterogeneous mechanism mainly on the surface of the α-phase dispersoids (Al15(Mn,Fe)3Si2), which thus significantly increase the quenching sensitivity of the alloy. The formation of these secretions at a low quenching rate causes, during subsequent aging, a decrease in the proportion and density of formation of strengthening particles of the β" phase, and also leads to an increase in their size and heterogeneity of distribution in the aluminum matrix, which reduces the potential of dispersion hardening during aging and corrosion resistance of the material.

First report of tobacco rattle virus infecting Weigela florida in the USA.

Weigela (Weigela florida (Bunge) A. DC., Family: Caprifoliaceae) are woody shrubs native to North China, Korea, and Japan. In the U.S., weigela are commonly used as landscape ornamental plants (McNamara et al. 2010). Two viruses have been reported in weigela: tomato spotted wilt orthotospovirus and impatiens necrotic spot orthotospovirus (Sastry et al. 2019). Ten weigela plants, originating from commercial nurseries in Minnesota, exhibiting chlorosis, chlorotic line patterns, and necrosis (e-Xtra) were submitted for virus diagnostics as potted plants at the University of Minnesota Plant Disease Clinic and the Virology Lab in 2019 and 2020 (five plants each year). Under greenhouse conditions, symptoms progressed from chlorosis to necrosis and even plant death in two of the five plants in 2019. Electron microscopy revealed rod-shaped particles of ≈20 nm in diameter and lengths between 40-200 nm with similar morphology to members of the genus Tobravirus (e-Xtra). Virus-like particles were enriched by ultracentrifugation and total nucleic acids were extracted from partial purifications using a phenol:chloroform extraction method (Lockhart et al. 1997). Tobacco rattle virus (TRV) was identified by cloning and sequencing of the 463bp amplicon obtained with the TRV detection primers described in Robinson, 1992. High-throughput sequencing (HTS) was done to confirm the TRV detection. A cDNA library was prepared from purified viral RNA using the TruSeq Stranded mRNA kit and sequenced on Illumina NovaSeq 6000 platform as 150 bp-paired end reads. A total of 44,316,446 raw data reads were obtained, preprocessed using the BBDuk plugin, and de novo assembled using SPAdes assembler. Viral contigs were identified using the NCBI BLASTX tool. The assembly of TRV RNA1 was 6,842 nt with 20,627,348 reads (47% of total reads) mapped to it and an average coverage per nucleotide at 323,639X. The assembly of TRV RNA2 was 3,033 nt with 22,769,253 reads (52% of total reads) mapped to it and an average coverage per nucleotide at 798,660X. NCBI GenBank accession numbers for the assemblies representing RNA1 and RNA2 are OQ408335 and OQ408336, respectively. NCBI BLASTn analysis showed the highest level of nucleotide identity to TRV genomic RNA segments 1 and 2, with 97% and 99% identity to the TRV isolate RNA1 (GQ903771) and RNA2 (GQ903772), respectively, that originated from Michigan potato. No other viral contigs were detected from the virion nucleic acid extraction by HTS, however this enrichment method doesn't exclude other viruses. In addition to using the detection primers by Robinson 1992, we designed primers based on our HTS data: TRV-WG-DetF3 5'- GACGAAGGAGGCTGTCATTGC-3' and TRV-WG-DetR3 5'-CGGACTATCGTGATGCCCATGC- 3'. RT-PCR amplicons from each of the 10 symptomatic plants were cloned and sequenced. Among these clones, Sanger sequence identities ranged between 96-100% compared to the HTS data and 98-99% to the TRV potato isolate from MI. To our knowledge, this is the first report of TRV infecting the ornamental host W. florida worldwide. TRV is a nematode-transmitted viral pathogen of economic importance, most notably in potatoes (Sastry et al. 2019). In the US, TRV has been reported on several landscape ornamentals, horticultural crops, and native habitats. Further research is needed to investigate the impact of TRV on the ornamental industry and the role of ornamentals as reservoirs for cultivated crops like potatoes.

Electrochemical deposition of a biofunctionalised silver and strontium substituted hydroxyapatite nanocomposite coating on a β-type titanium alloy

ABSTRACT As a result of hydroxyapatite’s (HAp) similarity to the mineral component of bone, it has been extensively investigated for biomedical application. To mimic the non-stoichiometric hydroxyapatite of bone or add positive features to it, different cationic and anionic substitutions have been studied. In this study, the nanocomposite coating of strontium (Sr) and silver (Ag) substituted HAp was deposited on a rarely investigated β type titanium alloy with low Young’s modulus to investigate its morphological and chemical features, crystallographic structure, thickness, biocompatibility, and hydrophilicity. The coating was deposited via a little reported electrochemical method which has the advantages of both electrolytic and electrophoretic deposition. The process is simple and can be conducted under mild experimental conditions to prevent potential high-temperature induced-thermal stress complications. The chemical, morphological and crystallographic features were characterised using EDAX, FE-SEM, and XRD analysis. The coating thickness was measured using a profilometry test. The biocompatibility and wetting behaviour were evaluated by MTT assay and the sessile drop technique, respectively. The coatings have shown rod-shaped, homogenous, and nano-sized HAp particles, with a close Ca/P ratio to stoichiometric apatite; meanwhile, Sr and Ag nanosphere particles are capable of modifying its surface. The coating can support cell growth and proliferation and shows a superhydrophilic surface.

Development of a novel flexible thin PWO(Er)/ZnO(Ag) nanocomposite for ionizing radiation sensing

Radiation dosimetry is an essential aspect of modern radiotherapy. Optically stimulated luminescence (OSL) dosimetry is a promising technique that uses materials to measure radiation doses. However, current OSL dosimeters are limited in their ability to provide comprehensive validation of spatial dose distributions, particularly in flexibility radiation sensitivity. In this regard, a novel flexible PWO(Er)/ZnO(Ag) nanocomposite sensor has been developed by a solvothermal procedure and its ionization radiation responses were investigated under UV, proton, laser 980 nm, and 241Am sources. The calculated alpha detection efficiency showed that the prepared PWO(Er)/ZnO(Ag) sensor is highly sensitive to alpha radiation (99.6 %) with good stability/repeatability and linear response. According to the Photo/Ionoluminescence study, the doped dual nanocomposite sample showed the strongest blue, green, and yellow emissions at room temperature compared with pure and single doped samples with an exciton lifetime of τ = 143.30 ±0.07 μs. The XRD, FTIR, Raman, and EDX results indicated that the prepared pure and doped nanocomposites have two-phase compositions of PWO and ZnO and related chemical compounds/elements in the nanocomposite structure. The morphologies of the PWO and PWO(Er) nanoparticles (NPs) were mostly cubic and heterogeneous with average particle sizes of 125 and 82 nm. ZnO and ZnO(Ag) had hexagonal, spherical, and rod-shaped particles with typical particle diameters of 130 and 90 nm, respectively. Our results indicate the prepared luminescent nanocomposites are transparent, flexible, highly stable, highly sensitive to ionizing radiation, and have the potential for practical use in optoelectronics and medical imaging in the future.

Improvement of microstructure and acquirement of excellent mechanical properties of high-Nb Ti2AlC/TiAl alloy by Ta under ultrasonic action in solid-liquid zone

To promote element diffusion in the solid-liquid two-phase region, optimize solidification microstructure, and improve the matching degree of strength and toughness, Ti–46Al–8Nb-2.6C-xTa (at. %) alloys were prepared by arc melting under the action of ultrasound. The lamellar colony, precipitate phase, elements distribution, and related mechanisms were analyzed. Results show that the relative content of the γ phase decreases, while the relative content of the α2 phase and Ti2AlC phase increases as the addition of Ta increases. The coarse long rod-shaped Ti2AlC transforms into short rod-shaped particles. The lamellar colony size reduces from 32.1 to 18.6 μm, the lamellar spacing reduces from 1.4 to 0.7 μm, and the aspect ratio of Ti2AlC reduces from 5.8 to 2.5 as the addition of Ta increases from 0 to 1.0 at. %. The acoustic streaming effect of ultrasound promotes the diffusion of tantalum in the solid-liquid two-phase region for a certain ultrasonic processing time. Tantalum is a heterogeneous nucleation particle of Ti2AlC particles and causes composition supercooling at the forefront of the solidification interface, which is the main reason for refining the microstructure. Compressive strength increases from 1996 to 2596 MPa and the strain increases from 25.4 to 29.3% as the addition of Ta increases from 0 to 0.6 at. %. The main reasons for improving the properties of alloy are the refinement of the microstructure and the formation of a large number of dislocations.

High-performance Al2O3 Composite Ceramics Modified with Short Rod-Shaped ZrO2 Particles

In this study, short rod-shaped monoclinic ZrO2 particles were synthesized from Zr(NO3)4.5H2O, Y(NO3)3 and KOH in a hydrothermal reaction. The reaction conditions, structure of the synthetic ZrO2 and effects of different concentrations of ZrO2 on the mechanical properties of Al2O3 composite ceramics were investigated. Dense monoclinic rod-shaped ZrO2 particles with rough surfaces were obtained when the hydrothermal reaction temperature was 180oC, the reaction time was 24 h and the KOH concentration was 6 mol/L. Results from energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction spectroscopy (XRD) confirmed the structure and composition of the reaction product. Composite ceramics were prepared by hot press sintering the synthetic ZrO2 with Al2O3, and optimal values of mechanical properties were obtained for 7.5 wt% zirconia. The ZrO2 strengthened the Al2O3 composite ceramics by mechanisms that included reinforcement by fine grains, enhancement by rod-shaped ZrO2 particles and phase transformation toughening.

Dynamic precipitation and deformation behaviors of a bimodal-grained WE43 alloy with enhanced mechanical properties

Achieving a high strength-ductility synergy in rolled Mg alloys remains a major challenge, especially for Mg alloys with high contents of rare earth (RE) elements, which are hard-to-deform and exhibit poor formability. In the present work, a bimodal grain structure consisting of fine grains (FGs) and coarse grains (CGs) has been achieved in a novel WE43 alloy sheet prepared by the hard-plate rolling (HPR) technique, which breaks the strength-ductility trade-off dilemma of the conventional WE43 alloy. Notably, the yield strength (YS) reaches as high as ∼312 MPa, presenting a remarkable improvement of YS (∼60 MPa) in comparison to conventionally rolled counterparts. Meanwhile, the ultimate tensile strength (UTS) and elongation-to-failure (EF) are ∼332 MPa and ∼11.8%, respectively, much higher than those of the wrought WE43 alloy reported in literature. Specifically, the disparate dislocation slips and dynamic precipitation behaviors in FGs and CGs have been studied in detail by combining EBSD and TEM analysis. The discrepancy of dynamic precipitation behavior in FGs and CGs is originated from the heterogeneous dislocation slip-dominated deformation behavior during HPR, related to initial grain orientations. It reveals that basal slips are dominant in the FG area, where equilibrium β-Mg14Nd2Y phase has precipitated along grain boundaries. In contrast, non-basal slips are prevalent and the metastable short rod-shaped β1 phase has formed within CGs. The enhanced YS of the present HPRed WE43 alloy sheet is mainly attributed to the formation of large amounts of extremely fine grains with an average size of ∼0.94 μm. The enhanced Orowan strengthening comes from the interaction between short rod-shaped β1 particles and non-basal dislocations (prismatic <a>, pyramidal <c + a> and pyramidal <a> dislocations) in CGs. In particular, the interactions between β1 particles and pyramidal <a> dislocations dominate the Orowan strengthening, leading to an increase of ∼34 MPa in the YS. Basal to basal slip transfers have been observed in FGs while non-basal slips are prevalent in CGs, which could be helpful for release the stress concentration near GBs. It is beneficial for preventing earlier fracture and thus enhancing the tensile strength combined with decent ductility.

Rod-shaped microparticles — an overview of synthesis and properties

Micro particles come in a wide variety of architectural designs and shapes. It is time to look beyond the conventional spherical morphology and focus on anisotropic systems. Rod-shaped micro particles in particular exhibit numerous unique behaviors based on their structural characteristics. Because of their various shapes, architectures, and material compositions, which are based on the wide range of synthesis possibilities, they possess an array of interesting characteristics and applications. This review summarizes and provides an overview of the substantial amount of work that has already been published in the field of rod-shaped micro particles. Nevertheless, it also reveals limitations and potential areas for development.

Shape Discrimination of Individual Aerosol Particles Using Light Scattering

We established an experimental apparatus by combining polarized light scattering and angle-resolved light scattering measurement technology to rapidly identify the shape of an individual aerosol particle. The experimental data of scattered light of Oleic acid, rod-shaped Silicon dioxide, and other particles with typical shape characteristics were analyzed statistically. To better study the relationship between the shape of particles and the properties of scattered light, the partial least squares discriminant analysis (PLS-DA) method was used to analyze the scattered light of aerosol samples based on the size screening of particles, and the shape recognition and classification method of the individual aerosol particle was established based on the analysis of the spectral data after nonlinear processing and grouping by particle size with the area under the receiver operating characteristic curve (AUC) as reference. The experimental results show that the proposed classification method has a good discrimination ability for spherical, rod-shaped, and other non-spherical particles, which can provide more information for atmospheric aerosol measurement, and has application value for traceability and exposure hazard assessment of aerosol particles.

Synthesis and performance of a cathode catalyst derived from Bauhinia accuminata seed pods in single and stacked microbial fuel cell.

The cathode catalyst in microbial fuel cell (MFC) plays a crucial role in scaling up. Activity of biomass-derived activated carbon catalysts with appropriate precursor selection in a natural clay membrane-based MFC of 250mL was studied. The performance of scaled up MFC of 1.5L capacity with two different configurations was monitored. Rod-shaped particles with slit-type pores and amorphous graphitic nature with a surface area of 800.37m2/g was synthesized. The intrinsic doping of heteroatoms N and P in the catalyst was with atomic weight percentages of 4.5 and 3.5, respectively and the deconvolution of N1 spectra confirmed pyridinic N and graphitic N content of 17.3% and 34.1% validating its suitability as a cathode catalyst. Electrochemical characterization of the catalyst coated SS mesh electrode confirmed that a loading of 5mg/cm2 rendered higher catalytic activity compared to bare SS mesh. The maximum power density in catalyst modified cell was 0.91W/m3 compared to 0.02W/m3 as obtained in a plain stainless steel electrode cell at a COD removal efficiency of 93.3%. Series, parallel, and parallel-series combinations of 6 cells showed a maximum voltage of 4.15V when connected in series and a maximum power density of 1.54W/m3 when connected in parallel. System with multielectrode assembly achieved better power and current density (0.84W/m3 and 1.97A/m3) than the mixed parallel series circuitry (0.7W/m3 and 0.57A/m3). These performance results confirm that the catalyst is effective in both stacked and hydraulically connected system.

Tandem photo-crosslinking/sol–gel reaction for the green synthesis of morphology-alterable, redox-responsive silica particles

Silica-based nanoparticles have been employed in versatile biomedical applications during the past decades and one of the important research focuses has been the synthesis of biothiol-degradable redox responsive silica to resolve the toxicity concerns of bioaccumulation. In the conventional sol-gel approach, the use of acidic or basic catalyst was always necessary. Solvent, heating, and templates were often applied. Besides, multi-step synthetic procedures were also frequently required to obtain the desired silane with disulfide-linkage for the following synthesis. We developed a facile and green photo-crosslinking coupled sol–gel reaction to produce disulfide-linked redox-responsive silica particles in water at room temperature. The reaction was template-free and initiated by visible light irradiation of photosensitizer (rose bengal). The particle size was tunable by adjusting the concentration of silica precursors, photosensitizer, and irradiation time of LED. The morphologies of the silica nanoparticles can be dramatically altered by simply changing the thiolated silica precursors. The kinetics of the silica precursors during the hydrolysis and photocrosslinking reactions played a critical role. Rose bengal served as a photosensitizer for silica nanoparticle formation and a photodynamic drug. The encapsulated rose bengal remained effective to generate singlet oxygen with superior performance than that of free ones. The disulfide bonds created in the silica matrix responded to reducing reagents, resulting in controllable self-disassembly. Additionally, we found that the presence of magnesium salts affected the rate of the photocrosslinking reaction, forming rod-shaped particles. The current results provide insights for future stimuli-responsive silica-based material development.

Increase in rod diffusivity emerges even in Markovian nature.

Rod-shaped particles embedded in certain matrices have been reported to exhibit an increase in their center of mass diffusivity upon increasing the matrix density. This increase has been considered to be caused by a kinetic constraint in analogy with tube models. We investigate a mobile rodlike particle in a sea of immobile point obstacles using a kinetic Monte Carlo scheme equipped with a Markovian process, that generates gaslike collision statistics, so that such kinetic constraints do essentially not exist. Even in such a system, provided the particle's aspect ratio exceeds a threshold value of about 24, the unusual increase in the rod diffusivity emerges. This result implies that the kinetic constraint is not a necessary condition for the increase in the diffusivity.

Synthesis, characterization, and in vitro apatite formation of strontium-doped sol-gel-derived bioactive glass nanoparticles for bone regeneration applications

The morphology of bioactive glass nanoparticles has been reported to impact apatite-forming ability, biocompatibility, and cell functions. In this study, mesoporous bioactive glass nanoparticles (MBGNs) of mixed morphologies with nominal compositions (%mol) given by 74Si O2_(26−x)CaO_xSrO, (where x=0,1,3,and5) were prepared through a modified sol-gel method. The MBGNs were characterized by thermal gravimetric analysis (TGA), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), N2 adsorption/desorption, X-ray diffraction (XRD), solid-state nuclear magnetic resonance (NMR), and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). In particular, the effect of Sr concentration on the glass structure, surface morphology, particle size, microstructure, chemical durability, ion release, and in vitro mineralization on the MBGNs was studied. All compositions showed similar thermal degradation profiles irrespective of Sr concentrations. SEM observation showed a mixture of aggregated spherical- and rod-shaped particles in which particle sizes decreased with increasing Sr concentration. Textural analysis showed a decrease in specific surface area with increasing Sr concentration. NMR analysis revealed a reduction in glass network polymerization with increasing Sr concentration. NMR analysis showed hasty depletion of modifier cations from the MBGNs to the simulated body fluid (SBF), the effect more prominent in the pristine sample. We observed prompt surface modifications on MBGNs as a response to their interaction with SBF that led to interconversion of 29Si speciation in the order QCa,Sr1+QCa,Sr2→QH2→QH3. SEM, EDX, and XRD revealed the formation of crystalline hydroxyapatite (HA) on the MBGNs after three days of immersion in SBF. In vitro apatite-forming ability of MBGNs decreased with increasing Sr concentration. The MBGNs revealed promising potential properties for applications in orthopedics, dentistry, wound healing, and drug delivery systems.