OsRAV1 Regulates Seed Vigor and Salt Tolerance During Germination in Rice.

Seed vigor is a complex trait encompassing seed germination, seedling emergence, growth, seed longevity, and stress tolerance, all are crucial for direct seeding in rice. Here, we report that the AP2/ERF transcription factor OsRAV1 (RELATED TO ABI3 AND VP1) positively regulates seed germination, vigor, and salt tolerance. Additionally, OsRAV1 was differently expressed in embryo and endosperm, with the OsRAV1 localized in the nucleus. Transcriptomic analysis revealed that OsRAV1 modulates seed vigor through plant hormone signal transduction and phenylpropanoid biosynthesis during germination. Haplotype analysis showed that rice varieties carrying Hap3 displayed enhanced salt tolerance during seed germination. These findings suggest that OsRAV1 is a potential target in breeding rice varieties with high seed vigor suitable for direct seeding cultivation.

Osmapentalenofurans Constructed by Reacting Os≡C1 of Osmapentalyne with Phenols.

Over the past decade, significant research efforts have focused on osmapentalyne, characterized by the more reactive Os≡C7 (Carbon atoms numbered in a clockwise direction on the osmapentalyne skeleton), across areas encompassing electrophilic, nucleophilic, and addition reactions. Nevertheless, the reactivity of osmapentalyne featuring Os≡C1 remains ripe for further exploration. In this investigation, we effectively synthesized a lineage of osmapentalenofurans through the nucleophilic reaction of osmapentalyne incorporating Os≡C1 with phenols. These resulting complexes demonstrate near-infrared luminescence traits in both solid and liquid states. Particularly noteworthy is the osmapentalenofuran derived from tetraphenylethane (TPE) unit, which showcases remarkable aggregation-induced emission ( AIE) property in the aggregated state. These osmapentalenofurans are also able to further extend their range of reactions, including reactions with base and isonitrile. This study not only broadens the scope of applications for metal aromatics but also furnishes valuable insights into the realm of specialized functional materials.

Targeting Nrf2/PHKG2 axis to enhance radiosensitivity in NSCLC.

While ferroptosis shows promise in anti-cancer strategy, the molecular mechanisms behind this process remain poorly understood. Our research aims to highlight the regulation of radiotherapy-induced ferroptosis in non-small cell lung cancer (NSCLC) via the NRF2/PHKG2 axis-mediated mechanism. To identify ferroptosis-associated genes associated with radioresistance in NSCLC, this study employed high-throughput transcriptome sequencing and Lasso risk regression analysis. Clinical samples were analyzed to confirm PHKG2 expression changes before and after radiotherapy. The study further examined ferritinophagy-related factors, intracellular iron levels, mitochondrial function, and ferroptosis in NSCLC cells undergoing radiation exposure to explore the effect of PHKG2 on radiosensitivity or radioresistance. The research also demonstrated the transcriptional inhibition of PHKG2 by NRF2 and created in situ transplantation tumor models of NSCLC to examine the role of NRF2/PHKG2 axis in NSCLC radiosensitivity and resistance in vivo. The Lasso risk regression model that incorporated ferroptosis-associated genes effectively predicted the prognosis of patients with NSCLC. Radiotherapy-sensitive tissues exhibited an increased expression of PHKG2. Overexpression of PHKG2 led to elevated intracellular iron levels by promoting ferritinophagy and increased mitochondrial stress-dependent ferroptosis induced by radiotherapy. PHKG2 transcription repression was achieved through NRF2. The FAGs-Lasso risk regression model can accurately predict the prognosis of NSCLC patients. Targeting Nrf2 upregulates the expression of PHKG2 and reverses radiotherapy resistance in NSCLC by promoting iron autophagy and inducing mitochondrial dysfunction, thereby increasing radiotherapy sensitivity.

Interactions between rice starch and flavor components and their impact on flavor.

Flavor is considered one of the most significant factors affecting food quality. However, it is often susceptible to environmental factors, so encapsulation is highly necessary to facilitate proper handling and processing. In this study, the structural changes in starch encapsulation and their effects on flavor retention were investigated using indica starch (RS) as a matrix to encapsulate three flavoring compounds, namely nonanoic acid, 1-octanol, and 2-pentylfuran. The rheological and textural results suggested that the inclusion of flavor compounds improved the intermolecular interactions between starch molecules, resulting in a significant increase in the physicochemical properties of starch gels in the order: nonanoic acid > 1-octanol > 2-pentylfuran. The XRD results confirmed the successful preparation of v-starch. Additionally, the inclusion complexes (ICs) were characterized using FT-IR, SEM, and DSC techniques. The results showed that v-starch formed complexes with Flavor molecules. The higher enthalpy of the complexes suggested that the addition of alcohols and acids could improve the intermolecular complexation between starch molecules. The retention rates of three flavor compounds in starch were determined using HS-GC, with the values of 51.7 %, 32.37 %, and 35.62 %. Overall, this study provides insights into novel approaches to enhance the quality and flavor retention, improve the storability and stability, reduce losses during processing and storage, and extend the shelf life of starchy products.

Top coal drawing law for an extra thick coal seam under the single round group drawing method.

To solve the problems of poor top coal drawing, lagging collapse, and difficulty in parallel operation of mining and drawing in extra-thick coal seams, considering the 8222 working face of the Tashan Mine as the engineering background, we first investigate the basic problems of fully mechanized top coal drawing mining in extra-thick coal seams using the single-round group drawing method (GDM). We then analyze the drawing law of top coal with different thicknesses under the single-round GDM from the aspects of top coal recovery (TCR) and drawing efficiency, coal loss mechanism, and the relation between TCR and gangue content (GC), providing a basis for determining the process parameters of GDM. Results indicate that as the top coal thickness increases, the number of drawing openings considerably influences drawing efficiency and top coal loss. And there is a notable thickness effect of the number of drawing openings on the top coal loss. There is a quantitative relationship among TCR, cumulative GC (CGC) and instantaneous GC (IGC), and CGC and TCR can be predicted based on the IGC. Consequently, theoretical analysis and numerical simulation results indicate that the optimal IGC threshold at the coal drawing openings between 31.2 and 40%. Through optimizing the coal drawing method and strictly controlling the IGC at the coal drawing openings on-site, the measured working face TCR increased from 75.25 to 90.12%, and CGC was controlled at approximately 9%. Meanwhile, the average coordination efficiency of mining and drawing time reaches 68.2%, effectively ensuring the construction of a coal mine with an annual output of 15 million tons.

Enhanced fabrication of size-controllable chitosan-genipin nanoparticles using orifice-induced hydrodynamic cavitation: Process optimization and performance evaluation.

Chitosan nanoparticles (NPs) possess great potential in biomedical fields. Orifice-induced hydrodynamic cavitation (HC) has been used for the enhancement of fabrication of size-controllable genipin-crosslinked chitosan (chitosan-genipin) NPs based on the emulsion cross-linking (ECLK). Experiments have been performed using various plate geometries, chitosan molecular weight and under different operational parameters such as inlet pressure (1-3.5 bar), outlet pressure (0-1.5 bar) and cross-linking temperature (40-70 °C). Orifice plate geometry was a crucial factor affecting the properties of NPs, and the optimized geometry of orifice plate was with single hole of 3.0 mm diameter. The size of NPs with polydispersity index of 0.359 was 312.6 nm at an optimized inlet pressure of 3.0 bar, and the maximum production yield reached 84.82 %. Chitosan with too high or too low initial molecular weight (e.g., chitosan oligosaccharide) was not applicable for producing ultra-fine and narrow-distributed NPs. There existed a non-linear monotonically-increasing relationship between cavitation number (Cv) and chitosan NP size. Scanning electron microscopy (SEM) test indicated that the prepared NPs were discrete with spherical shape. The study demonstrated the superiority of HC in reducing particle size and size distribution of NPs, and the energy efficiency of orifice type HC-processed ECLK was two orders of magnitude than that of ultrasonic horn or high shear homogenization-processed ECLK. In vitro drug-release studies showed that the fabricated NPs had great potential as a drug delivery system. The observations of this study can offer strong support for HC to enhance the fabrication of size-controllable chitosan-genipin NPs.

Single-cell transcriptomic sequencing data reveal aberrant DNA methylation in SMAD3 promoter region in tumor-associated fibroblasts affecting molecular mechanism of radiosensitivity in non-small cell lung cancer.

OBJECTIVE: Non-small cell lung cancer (NSCLC) often exhibits resistance to radiotherapy, posing significant treatment challenges. This study investigates the role of SMAD3 in NSCLC, focusing on its potential in influencing radiosensitivity via the ITGA6/PI3K/Akt pathway. METHODS: The study utilized gene expression data from the GEO database to identify differentially expressed genes related to radiotherapy resistance in NSCLC. Using the GSE37745 dataset, prognostic genes were identified through Cox regression and survival analysis. Functional roles of target genes were explored using Gene Set Enrichment Analysis (GSEA) and co-expression analyses. Gene promoter methylation levels were assessed using databases like UALCAN, DNMIVD, and UCSC Xena, while the TISCH database provided insights into the correlation between target genes and CAFs. Experiments included RT-qPCR, Western blot, and immunohistochemistry on NSCLC patient samples, in vitro studies on isolated CAFs cells, and in vivo nude mouse tumor models. RESULTS: Fifteen key genes associated with radiotherapy resistance in NSCLC cells were identified. SMAD3 was recognized as an independent prognostic factor for NSCLC, linked to poor patient outcomes. High expression of SMAD3 was correlated with low DNA methylation in its promoter region and was enriched in CAFs. In vitro and in vivo experiments confirmed that SMAD3 promotes radiotherapy resistance by activating the ITGA6/PI3K/Akt signaling pathway. CONCLUSION: High expression of SMAD3 in NSCLC tissues, cells, and CAFs is closely associated with poor prognosis and increased radiotherapy resistance. SMAD3 is likely to enhance radiotherapy resistance in NSCLC cells by activating the ITGA6/PI3K/Akt signaling pathway.

Effects of Hyperthyroidism on Venous Thromboembolism: A Mendelian Randomization Study.

Objective: Observational studies show the correlation between thyroid dysfunction and risk of venous thromboembolism. However, the causal effects remain uncertain. Our study was conducted to evaluate whether thyroid function and dysfunction were causally linked to the risk of venous thromboembolism. Methods: Publicly available summary data of thyrotropin (TSH) and free thyroxine (FT4), hypothyroidism, and hyperthyroidism were obtained from the ThyroidOmics Consortium and the UK Biobank. With single nucleotide polymorphisms (SNPs) as instrumental variables, the casual effects of genetically predicted TSH and FT4 and hypo- and hyperthyroidism on venous thromboembolism outcome were estimated through Mendelian randomization analysis methods (inverse variance weighted (IVW), MR-Egger, weighted median, simple mode, and weighted mode). Cochran's Q test was performed to evaluate the heterogeneity and horizontal pleiotropy. Results: Our study selected 15 FT4-, 36 TSH-, 3 hyperthyroidism-, and 79 hypothyroidism-associated SNPs as instrumental variables. The IVW analysis results showed that the odds ratio of venous thromboembolism for hyperthyroidism was 1.124 (95% confidence interval: 1.019-1.240; p = 0.019), demonstrating the casual effect of hyperthyroidism not FT4, TSH, and hypothyroidism on venous thromboembolism. No heterogeneity or horizontal pleiotropy was observed according to Cochran's Q test. Conclusion: Our Mendelian randomization analysis supports the causal effect of hypothyroidism on risk of venous thromboembolism. There is no evidence that genetically predicted TSH, FT4, and hypothyroidism have casual effects on venous thromboembolism. Future studies should be conducted to elucidate the underlying pathophysiological mechanisms.

OsFTL4, an FT-like Gene, Regulates Flowering Time and Drought Tolerance in Rice (Oryza sativa L.).

The initiation of flowering in cereals is a critical process influenced by environmental and endogenous signals. Flowering Locus T-like (FT-like) genes encode the main signals for flowering. Of the 13 FT-like genes in the rice genome, Hd3a/OsFTL2 and RFT1/OsFTL3 have been extensively studied and revealed to be critical for flowering. In this study, a rice FT-like gene, OsFTL4, was functionally characterized. Specifically, osftl4 mutants were generated using a CRISPR/Cas9 system. Compared with the wild-type control (Guangluai 4), the osftl4-1 and osftl4-2 mutants flowered 9.6 and 5.8 days earlier under natural long-day and short-day conditions, respectively. Additionally, OsFTL4 was mainly expressed in the vascular tissue, with the resulting OsFTL4 protein localized in both the nucleus and cytoplasm. Furthermore, OsFTL4 was observed to compete with Hd3a for the interaction with multiple 14-3-3 proteins. An analysis of the effects of simulated drought stress suggested that silencing OsFTL4 enhances drought tolerance by decreasing stomatal conductance and water loss. These results indicate that OsFTL4 helps integrate the flowering process and the drought response in rice.

Exosomal microRNA-506 inhibits biological activity of lung adenocarcinoma cells and increases sensitivity to cisplatin-based hyperthermia.

Exosomal microRNAs (miRNAs) play a vital role in the occurrence and development of lung adenocarcinoma (LUAD). Based on the bioinformatics analyses, the current study sought to explore the effects of exosomal miR-506 on LUAD cell biology and the efficacy of cisplatin (CDDP)-based hyperthermia (HT). After sample preparation, we identified decreased miR-506 and elevated ATAD2. LUAD cells were subsequently transfected with miR-506 mimic, oe-ATAD2 and PI3K/AKT signaling pathway inhibitor LY294002 to analyze effects of the miR-506/ATAD2/PI3K/AKT axis on cell biological processes and chemoresistance. Effects of exosomal miR-506 on sensitivity of LUAD cells to CDDP-based HT were further assessed in a co-culture system of BMSC-derived exosomes and LUAD cells, which was also validated in tumor-bearing nude mice. miR-506 down-regulated ATAD2 to inhibit the PI3K/AKT signaling pathway, thereby inhibiting the malignant phenotypes of LUAD cells and augmenting LUAD cell sensitivity to CDDP-based HT. Further, BMSCs-derived exosomes harboring miR-506 sensitized LUAD cells to DDP/HT both in vitro and in vivo. Collectively, our findings revealed that exosomal miR-506 sensitized LUAD cells to CDDP-based HT by inhibiting ATAD2/PI3K/AKT signaling pathway, offering a potential therapeutic target for LUAD treatment.

Fine Mapping of qTGW7b, a Minor Effect QTL for Grain Weight in Rice (Oryza sativa L.).

Grain weight is a key trait that determines rice quality and yield, and it is primarily controlled by quantitative trait loci (QTL). Recently, attention has been paid to minor QTLs. A minor effect QTL qTGW7 that controls grain weight was previously identified in a set of chromosomal fragment substitution lines (CSSLs) derived from Nipponbare (NPB)/93-11. Compared to NPB, the single segment substitution line (SSSL) N83 carrying the qTGW7 introgression exhibited an increase in grain length and width and a 4.5% increase in grain weight. Meanwhile, N83 was backcrossed to NPB to create a separating population, qTGW7b, a QTL distinct from qTGW7, which was detected between markers G31 and G32. Twelve near-isogenic lines (NILs) from the BC9F3 population and progeny of five NILs from the BC9F3:4 population were genotyped and phenotyped, resulting in the fine mapping of the minor effect QTL qTGW7b to the approximately 86.2-kb region between markers G72 and G32. Further sequence comparisons and expression analysis confirmed that five genes, including Os07g39370, Os07g39430, Os07g39440, Os07g39450, and Os07g39480, were considered as the candidate genes underlying qTGW7b. These results provide a crucial foundation for further cloning of qTGW7b and molecular breeding design in rice.

The comparative study of structural, electronic, and optical properties of hydrogen peroxide and its dihydrate under pressures: first-principle calculations.

Hydrogen peroxide (H2O2) is used as a fuel and propellant in fuel cells and rockets due to its prominent oxidizing and combustion properties. In addition, hydrogen peroxide, as the energetic material with the simplest molecular structure, exhibits general detonation performance under external stimulation. Based on the first-principle method, we calculated the two crystal structure, electronic properties related to sensitivity closely, optical properties of pure hydrogen peroxide, and 48wt.% hydrogen peroxide (H6O4) under pressure. We found that the band gaps of H2O2 and H6O4 become larger under pressure and the former is larger than the latter; neither has the tendency of metallization phase change. The added peak II of TDOS from H6O4 compared with H2O2 come from molecular H2O in crystal structure. The pressure-induced peak (peak 2 and peak II of TDOS from H2O2 and H6O4) splitting is caused by changes (stronger) in the intermolecular hydrogen bond environment in the crystal under pressure. The specific macroscopic optical properties have the characteristics of overall blue-shift under pressure, which is due to the blueshift of the conduction band and the increase of the band gap. We hope to provide some reference and guidance for deeper future research.

Antibiotic resistance genes in gut of breast-fed neonates born by caesarean section originate from breast milk and hospital ward air.

The human gut is a reservoir of antibiotic resistance genes (ARGs). Even in the absence of antibiotics, ARGs are present in large quantities in faeces of adults, children and even newborns. However, where and when ARGs are acquired remains unclear, as does the types of ARGs acquired. Herein, we recruited 82 pairs of women and their caesarean section newborns. Conventional culture methods and quantitative PCR were employed to detect nine species and six ARG types in meconia, faeces from 3-day-old newborns, amniotic fluid, colostrum, and hospital ward air samples. Furthermore, ARG transfer was explored by tracking Staphylococcus epidermidis isolated from faeces of 3-day-old newborns, colostrum and ward air samples using multi-locus sequence typing (MLST). No ARGs or microorganisms were detected in meconia or amniotic fluid. One or more ARGs were detected in 90.2% of faeces from 3-day-old newborns, and the mecA gene exhibited the highest detection rate (45.1%). ARGs were detected in 85.4% of colostra consistent with ARGs in faeces from 3-day-old newborns. Some ARGs were detected in ward air, and might also be a source of ARGs in neonatal faeces. Isolation of S. epidermidis from neonatal faeces was consistent with antibiotic resistance and gene profiles for colostrum samples. Traceability analysis of S. epidermidis showed that ARGs in neonatal faeces mainly originated from colostrum, and partly from ward air. After birth, neonates born by caesarean section obtain a variety of ARGs mainly from colostrum, and partly from ward air.

Prevalence characteristics of human papillomavirus (HPV) infection among women receiving physical examinations in the Shangcheng District, Hangzhou city, China.

This paper aimed to investigate the characteristics of female HPV infection in the Shangcheng District, Hangzhou city, China. The retrospective study was designed to analyze the HPV prevalence rate of 22,382 women receiving physical examinations from 2016 to 2020 in the Shangcheng District of Hangzhou city in China. A commercial kit was designed to detect the HPV genotypes. Trends were examined for age-specific groups (≤ 30 years, 31-44 years, 45-54 years, 55-64 years, ≥ 65 years). A receiver operating characteristic (ROC) analysis was used to assess the correlation of age classification in high risk HPV (HR-HPV) infection. 22.41% (5015/22,382) of samples were HPV positive, 91.28% (4578/5015) of HPV positive women were infected by HR-HPV. The most prevalent HR-HPV genotypes were 16, 52, 18, 58, 56, and 51. The trend of HPV prevalence showed the significant differences in age-specific groups (χ2 = 164.70, P < 0.001). Moreover, the areas under ROC curve (AUC) was 0.712 in 55-64 years group which showed a strong contribution of age classification for HR-HPV infection. This study provided baseline data on the prevalence characteristics of HPV infection and the critical age group of HR-HPV prevalence rate was 55-64 y among the samples receiving physical examinations.

Osmaindenes: Synthesis and Reversible Mechanochromism Characteristics.

A series of novel osmaindenes 1-6 bearing different substituents (CF3 , H, I, Br, OCH3 , N(Ph)2 ) has been synthesized by nucleophilic reaction of water with the corresponding aromatic osmanaphthalyne complexes. All osmaindenes 1-6 have been characterized by elemental analysis (EA) and nuclear magnetic resonance (NMR) spectroscopy, although the low solubilities of 3 and 4 precluded the accumulation of their 13 C NMR spectra. Osmaindenes 2, 3 and 5 have also been characterized by single-crystal X-ray diffraction analysis. Subsequently, through solid-state fluorescence spectroscopy, mechanochromic studies, and powder X-ray diffraction (XRD) analysis, we found that osmaindenes 1-6 fluoresce at wavelengths in the range 500-800 nm, while also displaying reversible mechanochromic properties. The solid-state fluorescence emission of 1 after grinding extends into the near-infrared region. This research provides new insight into the design and synthesis of metallic materials with excellent mechanochromic properties.

Hydrodynamic cavitation: A feasible approach to intensify the emulsion cross-linking process for chitosan nanoparticle synthesis.

Chitosan nanoparticles (NPs) exhibit great potential in drug-controlled release systems. A controlled hydrodynamic cavitation (HC) technique was developed to intensify the emulsion crosslinking process for the synthesis of chitosan NPs. Experiments were performed using a circular venturi and under varying operating conditions, i.e., types of oil, addition mode of glutaraldehyde (Glu) solution, inlet pressure (Pin), and rheological properties of chitosan solution. Palm oil was more appropriate for use as the oil phase for the HC-intensified process than the other oil types. The addition mode of water-in-oil (W/O) emulsion containing Glu (with Span 80) was more favorable than the other modes for obtaining a narrow distribution of chitosan NPs. The minimum size of NPs with polydispersity index of 0.342 was 286.5 nm, and the maximum production yield (Py) could reach 47.26%. A positive correlation was found between the size of NPs and the droplet size of W/O emulsion containing chitosan at increasing Pin. Particle size, size distribution, and the formation of NPs were greatly dependent on the rheological properties of the chitosan solution. Fourier transform infrared spectroscopy (FTIR) analysis indicated that the molecular structure of palm oil was unaffected by HC-induced effects. Compared with ultrasonic horn, stirring-based, and conventional drop-by-drop processes, the application of HC to intensify the emulsion crosslinking process allowed the preparation of a finer and a narrower distribution of chitosan NPs in a more energy-efficient manner. The novel route developed in this work is a viable option for chitosan NP synthesis.

Analysis of the Influencing Factors of the Hydroxyl Radical Yield in a Hydrodynamic Cavitation Bubble of a Chitosan Solution Based on a Numerical Simulation.

In this paper, the hydroxyl radical yield of a cavitation bubble and its influencing factors in the process of chitosan degradation with hydrodynamic cavitation in a single-hole orifice plate was investigated by a numerical simulation method. The hydroxyl radical yield of the cavitation bubble was calculated and analyzed by the Gilmore equation as the dynamic equation combined with the mass transfer equation, heat transfer equation, energy balance equation, and the principle of Gibbs free energy minimization. The influence of geometric parameters of the orifice plate and operating parameters on the formation of hydroxyl radicals was investigated. The results showed that the hydroxyl radicals produced at the moment of cavitation bubble collapse increased with the increase of the initial radius (R 0), upstream inlet pressure (P 1), downstream recovery pressure (P 2), downstream pipe diameter (d p), and the ratio of the orifice diameter to the pipe diameter (ß). The simulation results provide a certain basis for the regulation of hydrodynamic cavitation degradation of chitosan.

Upregulation of KCNQ1OT1 promotes resistance to stereotactic body radiotherapy in lung adenocarcinoma by inducing ATG5/ATG12-mediated autophagy via miR-372-3p.

Stereotactic body radiotherapy (SBRT) has emerged as a standard treatment for non-small-cell lung cancer. However, its therapeutic advantages are limited with the development of SBRT resistance. The SBRT-resistant cell lines (A549/IR and H1975/IR) were established after exposure with hypofractionated irradiation. The differential lncRNAs were screened by microarray assay, then the expression was detected in LUAD tumor tissues and cell lines by qPCR. The influence on radiation response was assessed via in vitro and in vivo assays, and autophagy levels were evaluated by western blot and transmission electron microscopy. Bioinformatics prediction and rescue experiments were used to identify the pathways underlying SBRT resistance. High expression of KCNQ1OT1 was identified in LUAD SBRT-resistant cells and tissues, positively associated with a large tumor, advanced clinical stage, and a lower response rate to concurrent therapy. KCNQ1OT1 depletion significantly resensitized A549/IR and H1975/IR cells to radiation by inhibiting autophagy, which could be attenuated by miR-372-3p knockdown. Furthermore, autophagy-related 5 (ATG5) and autophagy-related 12 (ATG12) were confirmed as direct targets of miR-372-3p. Restoration of either ATG5 or ATG12 abrogated miR-372-3p-mediated autophagy inhibition and radiosensitivity. Our data describe that KCNQ1OT1 is responsible for SBRT resistance in LUAD through induction of ATG5- and ATG12-dependent autophagy via sponging miR-372-3p, which would be a potential strategy to enhance the antitumor effects of radiotherapy in LUAD.

Study on mechanism of chitosan degradation with hydrodynamic cavitation.

Hydrodynamic cavitation is an effective method for chitosan degradation, of which the mechanism directly determines the molecular weight distribution of degradation products. In this study, based on the Monte Carlo simulation and experimental results, the mechanism of chitosan degradation with hydrodynamic cavitation and molecular weight distribution of products were analyzed. The results showed that the algorithm established in the simulation could effectively analyze degradation mechanism and the factors that influenced degradation mechanism and molecular weight distribution of products. The degradation with hydrodynamic cavitation was caused by chemical and mechanical effects, of which the former dominated the degradation process. The outlet and inlet angles and throat length of the cavitator had major and minor influences on the degradation pattern, respectively. The chemical effect led to random cuts resulting in wide distribution of the products, while the mechanical effect led to central cuts resulting in narrow distribution of the products. With more central cuts, the slide-shaped molecular weight distribution curve of degradation products was gradually transferred into a bell-shaped curve. These results provide instructions for researches on the molecular weight distribution of chitosan products degraded with hydrodynamic cavitation.

Ultrasonic assisted water-in-oil emulsions encapsulating macro-molecular polysaccharide chitosan: Influence of molecular properties, emulsion viscosity and their stability.

An ultrasonic technique was applied to formulation of two-phase water-in-paraffin oil emulsions loading a high-molecular polysaccharide chitosan (CS) and stabilized by an oil-soluble surfactant (Span80) at different operational conditions. The influence of chitosan molecular properties, phase volume ratio (φw), Span80 volume fraction (φs) and ultrasonic processing parameters were systemically investigated on the basis of mean droplet diameter (MDD) and polydispersity index (PDI) of emulsions. It was observed that the molecular weight (Mw) of CS was an important influential factor to MDD due to the non-Newtonian properties of CS solution varying with Mw. The minimum MDD of 198.5 nm with PDI of 0.326 was obtained with ultrasonic amplitude of 32% for 15 min at an optimum φw of 35%, φs of 8%, probe position of 2.2 cm to the top of emulsion, while CS with Mw of 400 kDa and deacetylation degree of 84.6% was used. The rise of emulsion viscosity and the reduction of negative zeta potential at φw increasing from 5% to 35% were beneficial to obtain finer droplets and more uniform distribution of emulsions, and emulsion viscosity could be represented as a monotonically-decreasing power function of MDD at the same φw. FTIR analysis indicated that the molecular structure of paraffin oil was unaffected during ultrasonication. Moreover, the emulsions exhibited a good stability at 4 °C with a slight phase separation at 25 °C after 24 h of storage. By analyzing the evolution of MDD, PDI and sedimentation index (SI) with time, coalescence model showed better fitting results as comparison to Ostwald ripening model, which demonstrated that the coalescence or flocculation was the dominant destabilizing mechanism for such W/O emulsions encapsulating CS. This study may provide a valuable contribution for the application of a non-Newtonian macromolecule solution as dispersed phase to generate nano-size W/O emulsions via ultrasound, and widen knowledge and interest of such emulsions in the functional biomaterial field.