Single Droplet Tweezer Revealing the Reaction Mechanism of Mn(II)-Catalyzed SO2 Oxidation.

Sulfate aerosol is one of the major components of secondary fine particulate matter in urban haze that has crucial impacts on the social economy and public health. Among the atmospheric sulfate sources, Mn(II)-catalyzed SO2 oxidation on aerosol surfaces has been regarded as a dominating one. In this work, we measured the reaction kinetics of Mn(II)-catalyzed SO2 oxidation in single droplets using an aerosol optical tweezer. We show that the SO2 oxidation occurs at the Mn(II)-active sites on the aerosol surface, per a piecewise kinetic formulation, one that is characterized by a threshold surface Mn(II) concentration and gaseous SO2 concentration. When the surface Mn(II) concentration is lower than the threshold value, the reaction rate is first order with respect to both Mn(II) and SO2, agreeing with our traditional knowledge. But when surface Mn(II) concentration is above the threshold, the reaction rate becomes independent of Mn(II) concentration, and the reaction order with respect to SO2 becomes greater than unity. The measured reaction rate can serve as a tool to estimate sulfate formation based on field observation, and our established parametrization corrects these calculations. This framework for reaction kinetics and parametrization holds promising potential for generalization to various heterogeneous reaction pathways.

ABSCISIC ACID-INSENSITIVE 5-KIP-RELATED PROTEIN 1-SHOOT MERISTEMLESS modulates reproductive development of Arabidopsis.

Soil (or plant) water deficit accelerates plant reproduction. However, the underpinning molecular mechanisms remain unknown. By modulating cell division/number, ABSCISIC ACID-INSENSITIVE 5 (ABI5), a key bZIP (basic (region) leucine zippers) transcription factor, regulates both seed development and abiotic stress responses. The KRP (KIP-RELATED PROTEIN) cyclin-dependent kinases (CDKs) play an essential role in controlling cell division, and SHOOT MERISTEMLESS (STM) plays a key role in the specification of flower meristem identity. Here, our findings show that abscisic acid (ABA) signaling and/or metabolism in adjust reproductive outputs (such as rosette leaf number and open flower number) under water-deficient conditions in Arabidopsis (Arabidopsis thaliana) plants. Reproductive outputs increased under water-sufficient conditions but decreased under water-deficient conditions in the ABA signaling/metabolism mutants abscisic acid2-1 (aba2-1), aba2-11, abscisic acid insensitive3-1 (abi3-1), abi4-1, abi5-7, and abi5-8. Further, under water-deficient conditions, ABA induced-ABI5 directly bound to the promoter of KRP1, which encodes a CDK that plays an essential role in controlling cell division, and this binding subsequently activated KRP1 expression. In turn, KRP1 physically interacted with SHOOT MERISTEMLESS (STM), which functions in the specification of flower meristem identity, promoting STM degradation. We further demonstrate that reproductive outputs are adjusted by the ABI5-KRP1-STM molecular module under water-deficient conditions. Together, our findings reveal the molecular mechanism by which ABA signaling and/or metabolism regulate reproductive development under water-deficient conditions. These findings provide insights that may help guide crop yield improvement under water deficiency.

Efficacy and Safety of Risankizumab in Patients with Psoriatic Arthritis: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

INTRODUCTION: Currently, the cause of psoriatic arthritis (PsA) is unknown, and the effectiveness of current drug treatments is unsatisfactory. In March 2019, the US Food and Drug Administration (FDA) approved risankizumab, a humanized immunoglobulin G1 (IgG1) monoclonal antibody targeting the p19 subunit of interleukin (IL)-23, for the treatment of PsA in adults. This study aimed to conduct a meta-analysis of double-blind, randomized, placebo-controlled trials to evaluate the effectiveness and safety of risankizumab in moderate-to-severe PsA. METHODS: We conducted a thorough search of relevant databases from the establishment of the databases to October 1, 2023. We conducted a meta-analysis using Stata 12.0 and utilized I2 and Egger tests to assess heterogeneity and publication bias among the studies. Bias assessment was performed using the risk bias map and bias risk summary diagram generated by Revman5.4 software. The review protocols were registered on PROSPERO (CRD42023451894) and adhered to the preferred reporting item of system evaluation (PRISMA) guideline. RESULTS: Six randomized controlled trials (RCTs) involving 5038 patients with PsA treated with either risankizumab or placebo were included in the analysis. At 24 weeks, the risankizumab group demonstrated a significantly higher American College of Rheumatology-20 (ACR20) response rate compared to the placebo group (RR 1.760, 95% CI 1.568-1.977, P < 0.001). Additionally, the risankizumab group showed a significantly higher Minimal Disease Activity (MDA) response rate compared to the placebo group (RR 1.827, 95% CI 1.048-3.184, P < 0.05). The risankizumab group also exhibited improvement in Short Form 36 Questionnaire (SF-36) score (SMD 0.51, 95% CI 0.33-0.69, P < 0.001), with significantly lower Health Assessment Questionnaire Disability Index (HAQ-DI) score (SMD - 0.27, 95% CI - 0.37 to - 0.17, P < 0.001) and higher Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) score (SMD 0.27, 95% CI 0.20-0.35, P < 0.001) compared to the placebo group. Moreover, the risankizumab group had a significantly lower Psoriasis Area and Severity Index (PASI) score (SMD - 6.12, 95% CI - 10.02 to 2.23, P < 0.001). A study by Mease et al. indicated that patients receiving risankizumab generally demonstrated numerical improvements in the Leeds Enthesitis Index (LEI), although the small sample size limits the evidence. Further research is necessary to provide evidence-based guidelines. There were no significant differences in the incidence of serious adverse events (SAE) and serious treatment-emergent adverse events (STEAE) between the risankizumab and placebo groups (RR 0.76, 95% CI 0.45-1.28, P = 0.31; RR 0.99, 95% CI 0.49-1.99, P = 0.97, respectively), and the overall incidence of adverse events (AE) was not comparable (RR 1.10, 95% CI 0.63-1.94, P = 0.73). CONCLUSION: Risankizumab showed superior efficacy across multiple outcome measures compared to placebo, with no significant increase in adverse events. Our findings endorse risankizumab as an excellent treatment option for PsA, offering valuable insights for clinicians and patients when choosing appropriate therapeutic interventions. TRIAL REGISTRATION: Retrospectively registered (CRD42023451894, 16 August 2023).

An injectable PC10ARGD/Cu2+/DOX hydrogel for combined chemodynamic and chemotherapy of tumors.

Nowadays, chemotherapy is a common clinical treatment for cancer, but it still faces many limitations and challenges. Therefore, the combination of chemotherapy and other treatments often enhances the effectiveness of treatments. Herein, an injectable hydrogel of PC10ARGD/Cu2+/DOX based on Cu2+, hydrophilic doxorubicin (DOX), and genetically engineered polypeptide PC10ARGD was prepared. First, Cu2+ was attached to the histidines in the PC10ARGD polypeptide by the coordination reaction to form PC10ARGD/Cu2+ hydrogel, then the PC10ARGD/Cu2+/DOX hydrogel was prepared by encapsulating the DOX into the PC10ARGD/Cu2+ hydrogel. The results of scanning electron microscopy showed that the PC10ARGD/Cu2+/DOX hydrogel displayed loose porous morphology. In vitro, reactive oxygen species production results showed that the PC10ARGD/Cu2+/DOX hydrogel could continuously produce ·OH in the presence of H2O2. In vitro MTT results showed that the PC10ARGD/Cu2+/DOX hydrogel had a good inhibitory effect on cell activity. Flow cytometry further confirmed the antitumor effect of the PC10ARGD/Cu2+/DOX hydrogel. In vivo experiment results showed that the tumor volume of mice treated with the PC10ARGD/Cu2+/DOX hydrogel was significantly inhibited compared with control groups, which was due to the combination of chemodynamic and chemotherapy. The results of body weight and blood analysis of mice showed that the PC10ARGD/Cu2+/DOX hydrogel possessed good biocompatibility.

Glucose status within dark-grown etiolated cotyledons determines seedling de-etiolation upon light irradiation.

Exposure of dark-grown etiolated seedlings to light triggers the transition from skotomorphogenesis/etiolation to photomorphogenesis/de-etiolation. In the life cycle of plants, de-etiolation is essential for seedling development and plant survival. The mobilization of soluble sugars (glucose [Glc], sucrose, and fructose) derived from stored carbohydrates and lipids to target organs, including cotyledons, hypocotyls, and radicles, underpins de-etiolation. Therefore, dynamic carbohydrate biochemistry is a key feature of this phase transition. However, the molecular mechanisms coordinating carbohydrate status with the cellular machinery orchestrating de-etiolation remain largely opaque. Here, we show that the Glc sensor HEXOKINASE 1 (HXK1) interacts with GROWTH REGULATOR FACTOR5 (GRF5), a transcriptional activator and key plant growth regulator, in Arabidopsis (Arabidopsis thaliana). Subsequently, GRF5 directly binds to the promoter of phytochrome A (phyA), encoding a far-red light (FR) sensor/cotyledon greening inhibitor. We demonstrate that the status of Glc within dark-grown etiolated cotyledons determines the de-etiolation of seedlings when exposed to light irradiation by the HXK1-GRF5-phyA molecular module. Thus, following seed germination, accumulating Glc within dark-grown etiolated cotyledons stimulates a HXK1-dependent increase of GRF5 and an associated decrease of phyA, triggering the perception, amplification, and relay of HXK1-dependent Glc signaling, thereby facilitating the de-etiolation of seedlings following light irradiation. Our findings, therefore, establish how cotyledon carbohydrate signaling under subterranean darkness is sensed, amplified, and relayed, determining the phase transition from skotomorphogenesis to photomorphogenesis on exposure to light irradiation.

Sugar status in preexisting leaves determines systemic stomatal development within newly developing leaves.

Stomata are pores found in the epidermis of stems or leaves that modulate both plant gas exchange and water/nutrient uptake. The development and function of plant stomata are regulated by a diverse range of environmental cues. However, how carbohydrate status in preexisting leaves might determine systemic stomatal formation within newly developing leaves has remained obscure. The glucose (Glc) sensor HEXOKINASE1 (HXK1) has been reported to decrease the stability of an ethylene/Glc signaling transcriptional regulator, EIN3 (ETHYLENE INSENSITIVE3). EIN3 in turn directly represses the expression of SUC2 (sucrose transporter 2), encoding a master transporter of sucrose (Suc). Further, KIN10, a nuclear regulator involved in energy homeostasis, has been reported to repress the transcription factor SPCH (SPEECHLESS), a master regulator of stomatal development. Here, we demonstrate that the Glc status of preexisting leaves determines systemic stomatal development within newly developing leaves by the HXK1-¦EIN3-¦SUC2 module. Further, increasing Glc levels in preexisting leaves results in a HXK1-dependent decrease of EIN3 and increase of SUC2, triggering the perception, amplification and relay of HXK1-dependent Glc signaling and thereby triggering Suc transport from mature to newly developing leaves. The HXK1-¦EIN3-¦SUC2 molecular module thereby drives systemic Suc transport from preexisting leaves to newly developing leaves. Subsequently, increasing Suc levels within newly developing leaves promotes stomatal formation through the established KIN10⟶ SPCH module. Our findings thus show how a carbohydrate signal in preexisting leaves is sensed, amplified and relayed to determine the extent of systemic stomatal development within newly developing leaves.

Baicalein Attenuates Neuroinflammation in LPS-Treated BV-2 Cells by Inhibiting Glycolysis via STAT3/c-Myc Pathway.

More and more evidence shows that metabolic reprogramming is closely related to the occurrence of AD. The metabolic conversion of oxidative phosphorylation into glycolysis will aggravate microglia-mediated inflammation. It has been demonstrated that baicalein could inhibit neuroinflammation in LPS-treated BV-2 microglial cells, but whether the anti-neuroinflammatory mechanisms of baicalein were related to glycolysis is unclear. Our results depicted that baicalein significantly inhibited the levels of nitric oxide (NO), interleukin-6 (IL-6), prostaglandin 2 (PGE2) and tumor necrosis factor (TNF-α) in LPS-treated BV-2 cells. 1H-NMR metabolomics analysis showed that baicalein decreased the levels of lactic acid and pyruvate, and significantly regulated glycolytic pathway. Further study revealed that baicalein significantly inhibited the activities of glycolysis-related enzymes including hexokinase (HK), 6-phosphate kinase (6-PFK), pyruvate kinase (PK), lactate dehydrogenase (LDH), and inhibited STAT3 phosphorylation and c-Myc expression. By using of STAT3 activator RO8191, we found that baicalein suppressed the increase of STAT3 phosphorylation and c-Myc expression triggered by RO8191, and inhibited the increased levels of 6-PFK, PK and LDH caused by RO8191. In conclusion, these results suggested that baicalein attenuated the neuroinflammation in LPS-treated BV-2 cells by inhibiting glycolysis through STAT3/c-Myc pathway.

Advancements in adipose-derived stem cell therapy for skin fibrosis.

Pathological scarring and scleroderma, which are the most common conditions of skin fibrosis, pathologically manifest as fibroblast proliferation and extracellular matrix (ECM) hyperplasia. Fibroblast proliferation and ECM hyperplasia lead to fibrotic tissue remodeling, causing an exaggerated and prolonged wound-healing response. The pathogenesis of these diseases has not been fully clarified and is unfortunately accompanied by exceptionally high medical needs and poor treatment effects. Currently, a promising and relatively low-cost treatment has emerged-adipose-derived stem cell (ASC) therapy as a branch of stem cell therapy, including ASCs and their derivatives-purified ASC, stromal vascular fraction, ASC-conditioned medium, ASC exosomes, etc., which are rich in sources and easy to obtain. ASCs have been widely used in therapeutic settings for patients, primarily for the defection of soft tissues, such as breast enhancement and facial contouring. In the field of skin regeneration, ASC therapy has become a hot research topic because it is beneficial for reversing skin fibrosis. The ability of ASCs to control profibrotic factors as well as anti-inflammatory and immunomodulatory actions will be discussed in this review, as well as their new applications in the treatment of skin fibrosis. Although the long-term effect of ASC therapy is still unclear, ASCs have emerged as one of the most promising systemic antifibrotic therapies under development.

Salvianolic Acid B Attenuates Hypertrophic Scar Formation In Vivo and In Vitro.

BACKGROUND: Hypertrophic scars (HTSs) are a fibroproliferative disorder that occur following skin injuries. Salvianolic acid B (Sal-B) is an extractant from Salvia miltiorrhiza that has been reported to ameliorate fibrosis in multiple organs. However, the antifibrotic effect on HTSs remains unclear. This study aimed to determine the antifibrotic effect of Sal-B in vitro and in vivo. METHODS: In vitro, hypertrophic scar-derived fibroblasts (HSFs) were isolated from human HTSs and cultured. HSFs were treated with (0, 10, 50, 100 µmol/L) Sal-B. Cell proliferation and migration were evaluated by EdU, wound healing, and transwell assays. The protein and mRNA levels of TGFßI, Smad2, Smad3, α-SMA, COL1, and COL3 were detected by Western blots and real-time PCR. In vivo, tension stretching devices were fixed on incisions for HTS formation. The induced scars were treated with 100 µL of Sal-B/PBS per day according to the concentration of the group and followed up for 7 or 14 days. The scar condition, collagen deposition, and α-SMA expression were analyzed by gross visual examination, H&E, Masson, picrosirius red staining, and immunofluorescence. RESULTS: In vitro, Sal-B inhibited HSF proliferation, migration, and downregulated the expression of TGFßI, Smad2, Smad3, α-SMA, COL1, and COL3 in HSFs. In vivo, 50 and 100 µmol/L Sal-B significantly reduced scar size in gross and cross-sectional observations, with decreased α-SMA expression and collagen deposition in the tension-induced HTS model. CONCLUSIONS: Our study demonstrated that Sal-B inhibits HSFs proliferation, migration, fibrotic marker expression and attenuates HTS formation in a tension-induced HTS model in vivo. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Tracking of Mutational Signature of SARS-CoV-2 Omicron on Distinct Continents and Little Difference was Found.

The Omicron variant is currently ravaging the world, raising serious concern globally. Monitoring genomic variations and determining their influence on biological features are critical for tracing its ongoing transmission and facilitating effective measures. Based on large-scale sequences from different continents, this study found that: (i) The genetic diversity of Omicron is much lower than that of the Delta variant. Still, eight deletions (Del 1-8) and 1 insertion, as well as 130 SNPs, were detected on the Omicron genomes, with two deletions (Del 3 and 4) and 38 SNPs commonly detected on all continents and exhibiting high-occurring frequencies. (ii) Four groups of tightly linked SNPs (linkage I-IV) were detected, among which linkage I, containing 38 SNPs, with 6 located in the RBD, increased its occurring frequency remarkably over time. (iii) The third codons of the Omicron shouldered the most mutation pressures, while the second codons presented the least flexibility. (iv) Four major mutants with amino acid substitutions in the RBD were detected, and further structural analysis suggested that the substitutions did not alter the viral receptor binding ability greatly. It was inferred that though the Omicron genome harbored great changes in antigenicity and remarkable ability to evade immunity, it was immune-pressure selected. This study tracked mutational signatures of Omicron variant and the potential biological significance of the SNPs, and the linkages await further functional verification.

Effect of boiling on texture of scallop adductor muscles and its mechanism based on label-free quantitative proteomic technique.

The mechanism behind textural changes in scallop adductor muscle during boiling was investigated through proteomic analysis, determination of water holding capacity (WHC) and oxidative indices, as well as observation with scanning electron microscopy and multiphoton nonlinear optical microscopy. The hardness and shear force showed the trend of first rising and then falling in 45 min-boiling time. The results suggested that short-time boiling caused the oxidation, denaturation and aggregation of proteins, resulting in the transverse contraction of myofibers and lateral cross-linked aggregation of muscle fibers and a rise in WHC, which led to the increase in hardness and shear force. While long-time boiling caused the progressive degradation of structural proteins such as fibrillin-1, collagen alpha-2(I) chain, myosin heavy chain, basement membrane-specific heparan sulfate proteoglycan core protein, and paramyosin, resulting in a loose myofibril network and the decrease in WHC, which led to the decrease in hardness and shear force.

Analysis of texture properties and water-soluble fraction proteome of sea cucumber body wall with different boiling heating treatment.

Label-free quantitative proteomic analysis was utilized to determine the key proteins that affect texture properties of sea cucumber body wall (SCBW) with different boiling heating treatment. 862, 363, 315, and 258 proteins were confirmed in water-soluble fractions from fresh group, 0.5 h-, 2 h- and 4 h-heat treatment group, respectively. During boiling heating treatment, proteins with an increased abundance in water-soluble fraction primarily belong to structural proteins, such as collagens, microfibril-associated proteins, glycoproteins, and muscle proteins. It was speculated that the degradation of these structural proteins caused the progressive disintegration of network skeleton of collagen fibres and FMs as well as the gelatinization, thus resulted in the decrease of hardness and shear force. Besides, the degradation of FMs was occurred layer by layer during boiling heating treatment, and the fibrilin-1 outer layer degraded first, followed by the fibrilin-2 core component.

Salvianolic Acid B Reduces the Inflammation of Fat Grafts by Inhibiting the NF-Kb Signalling Pathway in Macrophages.

BACKGROUND: Autologous fat grafting is a common method for soft tissue defect repair. However, the high absorption rate of transplanted fat is currently a bottleneck in the process. Excessive inflammation is one of the main reasons for poor fat transplantation. Salvianolic acid B (Sal-B) is a herbal medicine that shows promise for improving the effectiveness of fat transplantation. OBJECTIVE: The aim of this study was to improve fat graft survival by injecting Sal-B into fat grafts locally. METHODS: In vivo, 0.2 mL of Coleman fat was transplanted into nude mice along with Sal-B. The grafts were evaluated by histologic analysis at 2, 4, and 12 weeks posttransplantation and by microcomputed tomography at 4 weeks posttransplantation. In vitro ribonucleic acid sequencing, cell proliferation assays, anti-inflammatory activity assays, molecular docking studies, and kinase activity assays were performed in RAW264.7 cells to detect the potential mechanism. RESULTS: Sal-B significantly improved fat graft survival and attenuated adipose tissue fibrosis and inflammation. Sal-B also inhibited the polarization of M1 macrophages in fat grafts. In vitro, Sal-B inhibited the proliferation and activation of inflammatory pathways in RAW264.7 cells. In addition, Sal-B had an inhibitory effect on NF-κB (nuclear factor κ light polypeptide gene enhancer in B cells) signaling. This bioactivity of Sal-B may result from its selective binding to the kinase domain of the inhibitor of NF-κB kinase subunit ß. CONCLUSIONS: Sal-B could serve as a promising agent for improving the effect of fat transplantation by inhibiting the polarization of M1 macrophages through NF-κB signaling.

Differences in texture and digestive properties of different parts in boiled abalone muscles.

Differences in texture and digestive properties of different parts in 80 °C-boiled abalone muscle (adductor and transition part) after different processing time were investigated. With the extension of boiling time, the shear force and hardness of adductor increased first (6 min) and then decreased (30 min and 240 min), while the two indexes of transition part dramatically decreased after boiling for 6 min and then maintained until 240 min. Meanwhile, for adductor, the degree of protein hydrolysis, protein digestibility, and peptide transport levels declined with the extension of boiling time; While for transition part, those protein digestion and transport indexes significantly decreased first (6 min and 30 min) and then increased (240 min). By contrast, the adductor contained higher myofibrillar proteins content but lower collagen content than the transition part, which contributed to the differences in texture and digestive properties of the boiled samples.

Studying on effects of boiling on texture, microstructure and physiochemical properties of sea cucumber body wall and its mechanism using second harmonic generation (SHG) microscopy.

The structural foundation of texture changes in sea cucumber body wall (SCBW) during boiling was investigated using second harmonic generation (SHG) microscopy for the first time. The results from SHG signal imaging, light microscopy, scanning electron microscopy and transmission electron microscopy indicated the hierarchical structures of collagen in SCBW underwent progressive destruction with the prolongation of boiling time, including the depolymerization of collagen fibres, the uncoiling and disaggregation of collagen fibrils, the destruction of collagen microfibrils, the loosing of triple helix structure of collagen, and the degradation and gelatinization of collagen, which contributed to the progressive decline in texture indicators including shear force and hardness. SHG analysis also indicated that although collagen macromolecules such as collagen fibres, collagen fibrils and collagen microfibrils could be observed in 0.5 h-boiled and 2 h-boiled SCBW, monomeric collagen, the basic structural components of those macromolecules, has been already damaged.

Construction and validation of a novel Ferroptosis-related gene signature predictive model in rectal Cancer.

BACKGROUND: Rectal cancer (RC) is one of the most common malignant tumors. Ferroptosis is an iron-dependent form of cell death, which plays an important role in various cancers. However, the correlation between ferroptosis-related genes (FRGs) and prognosis in RC remains unclear. METHODS: Gene expression data from The Cancer Genome Atlas Rectum adenocarcinoma (TCGA-READ) and GSE87211 were downloaded. Clustering and functional enrichment were evaluated. A FRGs risk score was established based on the univariate Cox analysis and the Least absolute shrinkage and selection operator (LASSO) analysis. K-M analysis and ROC analysis were conducted to determine prognostic values. qRT-PCR was performed to validate levels of mRNA expression. Multivariate Cox analysis was used to build a prognostic prediction model based on the risk score. RESULTS: Based on FRGs, RC patients were grouped into two clusters. In the functional enrichment of differentially expressed genes between the two clusters, immune-related pathways dominated. A novel FRGs signature with 14 genes related to the overall survival (OS) of RC was established. qRT-PCR of the 14 genes identified TP63, ISCU, PLIN4, MAP3K5, OXSR, FANCD2 and ATM were overexpressed in RC tissue; HSPB1, MAPK1, ABCC1, PANX1, MAPK9 and ATG7 were underexpressed; TUBE1 had no difference. The high-risk group had a significantly lower OS than the low-risk group (P < 0.001), and ROC curve analysis confirmed the signature's predictive capacity. Multivariate analysis demonstrated that the risk score and age were independent prognostic factors. CONCLUSION: A novel FRGs model can be used to predict the prognosis in RC, as well as to guide individual treatment.

Effects of Boiling Processing on Texture of Scallop Adductor Muscle and Its Mechanism.

The objective of this study was to reveal the effects of boiling processing on the texture of scallop adductor muscle (SAM) and its mechanism. Compared to the fresh sample, all the texture indicators, including the hardness, chewiness, springiness, resilience, cohesiveness, and shear force of 30-s- and 3-min-boiled SAMs increased time-dependently (p < 0.05). As the boiling time increased further to 15 min, the shear force and cohesiveness still increased significantly (p < 0.05), and the resilience and hardness were maintained (p > 0.05), but the springiness and chewiness decreased significantly (p < 0.05). The overall increase in the texture indicators of the boiled SAMs was due to the boiling-induced protein denaturation, aggregation, and increased hydrophobicity, resulting in the longitudinal contraction and lateral expansion of myofibrils, the longitudinal contraction and lateral cross-linked aggregation of muscle fibers, and the loss of free water. However, the decreasing springiness and chewiness of the 15-min-boiled SAMs was due to the significant degradation of proteins (especially collagen), resulting in the destruction of the connective tissue between the muscle fiber clusters. Both from a subjective sensory point of view and from the objective point of view of protein denaturation and degradation, 3-min-boiled SAMs are recommended. The quality improvement of thermally processed products by controlled, moderate cooking is of practical value from the perspective of food consumption.

Effect of different sous-vide cooking conditions on textural properties, protein physiochemical properties and microstructure of scallop (Argopecten irradians) adductor muscle.

Among 26 sous-vide cooking conditions of scallop adductor muscle (SAM), 65 °C-5.5 h, 70 °C-1.5 h and 100 °C-5 min were selected by the differential scanning calorimetry analysis. After sous-vide cooking, the shear force, hardness, springiness, cohesiveness, chewiness and recoverability of SAM increased significantly compared to fresh sample. The cooking also changed the secondary structures of the proteins in SAM with the rising ß-sheet and descending α-helix, and the chemical interactions with the rising hydrophobic interactions and disulfide bonds but the descending ionic bonds and hydrogen bonds. These caused the longitudinal shrinkage and transverse aggregation of muscle fibers, and the aggregation and cross-linking between myofibrils which led to the squeeze of immobile water from myofibril network structure. This indicated that the denaturation, oxidation, aggregation and cross-linking of proteins caused by heat treatment changed the microstructure and water distribution, which contributed to the increased textural indicators of sous-vide cooked SAM.

Rapid Sulfate Formation via Uncatalyzed Autoxidation of Sulfur Dioxide in Aerosol Microdroplets.

Severe winter haze events in Beijing and North China Plain are characterized by rapid production of sulfate aerosols with unresolved mechanisms. Oxidation of SO2 by O2 in the absence of metal catalysts (uncatalyzed autoxidation) represents the most ubiquitous SO2 conversion pathway in the atmosphere. However, this reaction has long been regarded as too slow to be atmospherically meaningful. This traditional view was based on the kinetic studies conducted in bulk dilute solutions that mimic cloudwater but deviate from urban aerosols. Here, we directly measure the sulfate formation rate via uncatalyzed SO2 autoxidation in single (NH4)2SO4 microdroplets, by using an aerosol optical tweezer coupled with a cavity-enhanced Raman spectroscopy technique. We find that the aqueous reaction of uncatalyzed SO2 autoxidation is accelerated by two orders of magnitude at the high ionic strength (∼36 molal) conditions in the supersaturated aerosol water. Furthermore, at acidic conditions (pH 3.5-4.5), uncatalyzed autoxidation predominately occurs on droplet surface, with a reaction rate unconstrained by SO2 solubility. With these rate enhancements, we estimate that the uncatalyzed SO2 autoxidation in aerosols can produce sulfate at a rate up to 0.20 µg m-3 hr-1, under the winter air pollution condition in Beijing.

Effect of boiling on texture of abalone muscles and its mechanism based on proteomic techniques.

The precise mechanism of texture changes in abalone muscles during boiling was investigated using quantitative proteomic analysis. A total 353 water-soluble proteins were identified in fresh abalone muscle. The number was decreased to 233 (6 min) and 201 (30 min), and then increased to 271 (240 min) during boiling. The undetectable protein in water-soluble fraction caused by boiling mainly belong to hemocyanins, protein kinases, dehydrogenases, phosphorylases, and transferases, while the newly identified proteins in water-soluble fraction during boiling mainly belong to collagen and myofibrillar proteins (MPs).Additionally, results also showed that boiling caused protein oxidation, denaturation, aggregation, crosslinking and degradation. Combined with the texture changes of abalone muscles during boiling, it was speculated that the oxidation, denaturation, aggregation and crosslinking of proteins led to the increase of shear force, however, the degradation of structural proteins such as MPs and collagen caused the decreases in shear force and hardness.