Mechanism Of Suppression Research Articles

Combustion-explosion suppression and environmental protection of typical sulfur-containing hazardous chemicals.

Sulfur, as a crucial chemical raw, poses increased combustion-explosion risks when mixed with other hazardous substances due to its dual nature as both an oxidant and a reducing agent. Additionally, sulfur-induced combustion and explosions can result in environmental pollution. Combustion-explosion suppression technology plays a crucial role in industrial production by effectively preventing hazardous chemical explosion incidents. This research investigates the combustion-explosion suppression of black powder, a common hazardous chemical containing sulfur, by utilizing two solid-based blast suppressants, NH4H2PO4 and NaHCO3. On this basis, examining changes in the oxidation states of sulfur and explaining the mechanisms of combustion-explosion suppression through the examination of combustion-explosion products. Additionally, numerical calculations are employed to analyze the evolution patterns of gaseous and solid-phase products throughout the entire combustion-explosion process. Research indicates that NaHCO3 exhibits a more effective combustion-explosion suppression effect on black powder compared to NH4H2PO4, which attributed to the valence state transformation of sulfur and the reduction of carbon oxidation. Furthermore, with the enhancement of combustion-explosion suppression effect, K2S, which a pollutes the environment, is gradually transform converted into potassium fertilizer K2SO4, which benefits plants. These results offer new insights into the research of combustion-explosion suppression of sulfur-containing substances and environmental protection strategies.

Cortisol affects macrophage polarization by inducing miR-143/145 cluster to reprogram glucose metabolism and by promoting TCA cycle anaplerosis

Chronic stress can have adverse consequences on human health by disrupting the hormonal balance in our body. Earlier, we observed elevated levels of cortisol, a primary stress hormone, and some exosomal microRNAs in the serum of breast cancer patients. Here, we investigated the role of cortisol in microRNA induction and its functional consequences. We found that cortisol induced the expression of miR-143/145 cluster in human monocyte (THP1 and U937)-derived macrophages but not in breast cancer cells. In silico analysis identified glucocorticoid-response element in the upstream CARMN promoter utilized by the miR-143/145 cluster. Enhanced binding of glucocorticoid-receptor (GR) upon cortisol exposure and its regulatory significance was confirmed by chromatin-immunoprecipitation and promoter-reporter assays. Further, cortisol inhibited IFNγ-induced M1 polarization and promoted M2 polarization, and these effects were suppressed by miR-143-3p and miR-145-5p inhibitors pretreatment. Cortisol-treated macrophages exhibited increased oxygen-consumption rate (OCR) to extracellular-acidification rate (ECAR) ratio, and this change was neutralized by functional inhibition of miR-143-3p and miR-145-5p. HK2 and ADPGK were confirmed as the direct targets of miR-143-3p and miR-145-5p, respectively. Interestingly, silencing of HK2 and ADPGK inhibited IFNγ-induced M1 polarization, but failed to induce M2 polarization, since it suppressed both ECAR and OCR, while OCR was largely sustained in cortisol-treated M2-polarized macrophages. We found that cortisol treatment sustained OCR by enhancing fatty acid and glutamine metabolism through upregulation of CPT2 and GLS, respectively, to support M2 polarization. Thus, our findings unfold a novel mechanism of immune suppression by cortisol and open avenues for preventive and therapeutic interventions.

Tailor-made green composts with suppressive properties against tracheofusariosis of wild rocket (Diplotaxis tenuifolia): Useful option for sustainable circular horticulture

Intensive cultivation systems of wild rocket (Diplotaxis tenuifolia) are threatened by the outbreak of tracheofusariosis caused by the soil-borne fungal pathogen Fusarium oxysporum f. sp. raphani. The disease is difficult to eradicate by curative methods due to the endophytic progression of the pathogen. Suppressive composts can help to prevent this adversity by providing organic matter carrying chemical and biological components that can directly and/or indirectly interfere with the plant-pathogen system. In this study, a collection of seven promising composts from different selected green feedstocks were investigated for their suppressive properties towards wild rocket Fusarium wilting. In planta assays identified two composts, obtained from olive tree pruning + plant and tomato residues, and from olive waste + straw + wool residues, with the highest levels of suppressiveness, influenced by both application dose and plant development stage. These active composts showed overlapping 13C NMR profiles as in vivo suppressiveness, being positively correlated with the organic aliphatic alkyl, O-Aryl and carboxyl C fractions and subsequently with the hydrophobic index and alkyl ratio, and negatively with the lignin ratio. On the contrary, although biotic compost components showed antifungal effects, biological properties did not correlate with in planta wilting suppression. Consistently, reflectance spectroscopy in the Vis-NIR-SWIR highlighted the clustering of samples depending on their feedstock and chemical composition. The results allow the hypothesis of a plant-mediated suppression mechanism. The composting of crop residues improves the circularity of horticulture and makes it possible to produce, from selected matrices, tailored compost towards the sustainable cultivation of wild rocket.

Phage-antibiotic synergy suppresses resistance emergence of Klebsiella pneumoniae by altering the evolutionary fitness.

Phage-antibiotic synergy (PAS) has been recently proposed as a superior strategy for the treatment of multidrug-resistant pathogens to effectively reduce bacterial load and slow down both phage and antibiotic resistance. However, the underlying mechanisms of resistance suppression by PAS have been poorly and rarely been studied. In this study, we tried to understand how PAS suppresses the emergence of resistance using a hypervirulent Klebsiella pneumoniae (KP) strain and a novel phage H5 in combination with ceftazidime (CAZ) as a model. Our study reveals a novel mechanism by which PAS drives altered evolutionary trajectory of bacterial populations, leading to suppressed emergence of resistance. The findings advance our understanding of how PAS suppresses the emergence of resistance, and are imperative for optimizing the efficacy of phage-antibiotic therapy to further improve clinical outcomes.

Suppression of Interferon Response and Antiviral Strategies of Bunyaviruses.

The order Bunyavirales belongs to the class of Ellioviricetes and is classified into fourteen families. Some species of the order Bunyavirales pose potential threats to human health. The continuously increasing research reveals that various viruses within this order achieve immune evasion in the host through suppressing interferon (IFN) response. As the types and nodes of the interferon response pathway are continually updated or enriched, the IFN suppression mechanisms and target points of different virus species within this order are also constantly enriched and exhibit variations. For instance, Puumala virus (PUUV) and Tula virus (TULV) can inhibit IFN response through their functional NSs inhibiting downstream factor IRF3 activity. Nevertheless, the IFN suppression mechanisms of Dabie bandavirus (DBV) and Guertu virus (GTV) are mostly mediated by viral inclusion bodies (IBs) or filamentous structures (FSs). Currently, there are no effective drugs against several viruses belonging to this order that pose significant threats to society and human health. While the discovery, development, and application of antiviral drugs constitute a lengthy process, our focus on key targets in the IFN response suppression process of the virus leads to potential antiviral strategies, which provide references for both basic research and practical applications.

Evaluating Mechanisms of Soil Microbiome Suppression of Striga Infection in Sorghum.

The root parasitic weed Striga hermonthica has a devastating effect on sorghum and other cereal crops in Sub-Saharan Africa. Available Striga management strategies are rarely sufficient or not widely accessible or affordable. Identification of soil- or plant-associated microorganisms that interfere in the Striga infection cycle holds potential for development of complementary biological control measures. Such inoculants should be preferably based on microbes native to the regions of their application. We developed a method to assess microbiome-based soil suppressiveness to Striga with a minimal amount of field-collected soil. We previously used this method to identify the mechanisms of microbe-mediated suppression of Striga infection and to test individual microbial strains. Here, we present protocols to assess the functional potential of the soil microbiome and individual bacterial taxa that adversely affect Striga parasitism in sorghum via three major known suppression mechanisms. These methods can be further extended to other Striga hosts and other root parasitic weeds. Key features • This protocol provides a detailed description of the methods used in Kawa et al. [1]. • This protocol is optimized to assess soil suppressiveness to Striga infection by using natural field-collected soil and the same soil sterilized by gamma-radiation. • This protocol is optimized to test bacterial (and not fungal) isolates. • This protocol can be easily extended to other host-parasite-microbiome systems.

Fully biobased approach for sustainable flame retardancy, antibacterial and anti-UV modification of silk fabric

The versatile modification of silk fabric using a fully biobased approach is intriguing. In this study, phytic acid and vanillin, which are plant extracts, were utilized to synthesize reactive vanillin phytate ester for modifying silk fabric to achieve durable flame retardancy, antibacterial and anti-UV performance. The multifunctional properties, thermal resistance, smoke and heat suppression capacity, flame-retardant durability and mechanism of modified silk fabrics were investigated. The vanillin phytate ester imparted high antimicrobial and UV resistance to silk fabric, achieving a 97 % inhibition rate against Escherichia coli and reaching an “excellent” level of UV protection. The modified silk fabric also possessed the self-extinguishing capacity, with a limiting oxygen index value as high as 33.5 %. There was also a significant reduction of 71.7 % in peak heat release and 40 % in smoke release compared with those of the original silk. After undergoing 20 washing cycles, the modified silk fabrics also self-extinguished and passed the vertical burning test, and such good washing resistance was achieved by the Schiff base cross-linking of vanillin phytate ester on the silk fabric. An intumescent flame-retardant mechanism was also identified by char residue analyses, which was driven by the synergistic charring action of phosphate groups and aromatic structures.

Resolvent Analysis for Subsonic Compressor With Impedance Boundary Condition Casing Treatment

Abstract A resolvent analysis framework for the axial compressor is established, and the impedance optimization is achieved based on the resolvent analysis framework for the impedance boundary condition casing treatment. This framework is derived by treating the nonlinearity in the perturbation equations as an unknown forcing, the linear relationship between wall impedance and energy gains is obtained. The validity of this framework is confirmed through experiments on rotating inlet distortion, which captures the most susceptible frequency for the stall points of the compressor. The resolvent analysis framework further confirms that the first-order circumferential mode exhibits the highest energy in the given cases. Subsequently, the proposed impedance optimization method is tested under throttling operating conditions, especially focusing on the first-order circumferential mode. The introduction of a favorable impedance boundary condition notably reduces energy gain within the low-order circumferential mode and in the range of the rotor rotating frequency, particularly in near-stall operating conditions. The energy suppression mechanism of the impedance boundary condition casing treatment is investigated, demonstrating that the impedance boundary condition, with an optimal impedance value, significantly suppresses perturbations compared to the case with the solid wall boundary condition. Lastly, a design method for the impedance boundary condition casing treatment is discussed, offering a reliable theoretical design tool for enhancing the stall margin of axial compressors.

An examination of the motivation to manage distraction

Individuals exhibit limited awareness of when their attention is captured by salient but irrelevant stimuli, and it has long been argued that involuntary attentional capture by such stimuli is minimally disruptive to information processing. Yet, robust mechanisms of distractor suppression are hypothesized to support the control of attention, which presumably serve in the interest of managing distraction. In the present study, I examine whether participants are aware of the cost of distraction with respect to task performance, and whether they are motivated to manage this cost even when it is effortful to do so. Across three experiments, participants were willing to exert physical effort in order to reduce the frequency with which they encountered physically salient distractors, and in a fourth experiment tended to prefer trials with fewer distractors when given a choice over distractor frequency. Importantly, the amount of physical effort exerted varied as a function of the degree to which task-irrelevant distractors impaired search performance, suggesting that people are sensitive to the cost of distraction.

Aeroacoustics of a Square Finite-Wall-Mounted Cylinder in Pressure-Gradient Flows

An experimental investigation of the wake flow structures, surface pressure fluctuations, and noise production of a square finite-wall-mounted cylinder with an aspect ratio of 2.4 is presented. The cylinder was immersed in flows with favorable, near-zero, and adverse pressure gradients at a Reynolds number of 48,000, based on cylinder width. Far-field noise, unsteady surface pressure, and particle image velocimetry measurements were taken simultaneously using the open-jet pressure-gradient test rig in the UNSW Anechoic Wind Tunnel. Favorable and adverse pressure gradients were found to enhance and suppress the cylinder tonal noise, respectively. A favorable pressure gradient reduced the size of the recirculation region in the wake, which intensified the free-end downwash and suppressed the junction upwash. The intensities of the cylinder surface pressure fluctuations were slightly increased at the primary and secondary shedding Strouhal numbers (based on cylinder width) of approximately 0.1 and 0.2. Conversely, the recirculation region expanded under an adverse pressure gradient, with the downwash weakened and the upwash enhanced. The peaks in the surface pressure spectra were noticeably attenuated at the primary shedding Strouhal number and completely suppressed at the secondary Strouhal number. Wake flow structures correlated with the surface pressure fluctuations and far-field noise were identified to understand the enhancement or suppression mechanisms of the surface pressure fluctuations and the associated shedding regimes.

Plasmids affect microindel mutations in Acinetobacter baylyi ADP1

Plasmids can impact the evolution of their hosts, e.g. due to carriage of mutagenic genes, through cross-talk with host genes or as result of SOS induction during transfer. Here we demonstrate that plasmids can affect the level of microindel mutations in the host genome. These mutations are driven by the production of single-stranded DNA molecules that invade replication forks at microhomologies and subsequently get integrated into the genome. Using the gammaproteobacterial model organism Acinetobacter baylyi, we show that carriage of broad host range plasmids from different incompatibility groups can cause microindel mutations directly or indirectly. The plasmid vector pQLICE belonging to the incompatibility group Q (IncQ) and replicating by a characteristic strand displacement mechanism can generate chromosomal microindel mutations directly with short stretches of DNA originating from pQLICE. In addition, results with the IncP plasmid vector pRK415 (theta replication mechanism) show that the presence of plasmids can increase microindel mutation frequencies indirectly (i.e., with chromosomal ectopic DNA), presumably through plasmid-chromosome interactions that lead to DNA damages. These results provide new mechanistic insights into the microindel mutation mechanism, suggesting that single-stranded DNA repair intermediates are the causing agents. By contrast, the IncN plasmid RN3 appears to suppress host microindel mutations. The suppression mechanism remains unknown. Other plasmids in this study (belonging to IncA/C2, IncW, pBBR incompatibility groups) confer ambiguous or no quantifiable mutagenic effects.

Investigation of mechanisms on leading edge vortex generation and suppression in vaned diffuser of a centrifugal compressor

This study numerically investigates the mechanisms for generating and suppressing the leading edge vortex (LEV) in a vaned diffuser of a centrifugal compressor, aiming to enhance the compressor's stable operating range. Detailed analyses focus on the mechanisms of the rotating stall and the initiation process of the LEV. Notably, the end wall contouring method is applied to vaned diffuser to suppress the LEV and improve diffuser stability. The suppression mechanisms of the LEV are examined to deepen the understanding of stability enhancement mechanisms. Results demonstrate that, under stall conditions, the vaned diffuser experiences two-cell rotating stalls moving opposite to the impeller rotation direction, each rotating at approximately 12% of impeller rotation speed. The formation of diffuser stall is attributed to a longitudinal vortex developing from the LEV and causing the passage blockage. The increasing spanwise distortion of leading edge (LE) incidence angles and circumferential distortion of static pressures at the diffuser inlet promote the evolution of the longitudinal vortex from LEV. The end wall contouring of vaned diffuser effectively enhances the compressor's stable operating range by 15.10% and 8.90% toward lower flow rate conditions for machine Mach numbers 1.3 and 1.2, respectively. At near-stall points, the end wall contoured diffuser reduces spanwise distortion of LE incidence angles and circumferential distortion of static pressures at the diffuser inlet, mitigates the LE flow separation and corner separation, suppresses the generation and development of the LEV, delays the onset of rotating stall in vaned diffuser, and thereby improves the stable operating range of centrifugal compressor stage.

Suppressing of alkaline aggregate reaction (AAR) through waterproofing of concrete surface, aggregates, and mortars

Water is necessary for the alkali aggregate reaction to occur and this study investigates the impact of waterproofing on alkali-aggregate reaction (AAR) in concrete by separating water from alkali reactive aggregates through surface, aggregate, and matrix treatments. Accelerated mortar bar tests (AMBT) are conducted to analyze the expansion caused by alkali aggregates. Furthermore, the suppressive mechanism of waterproofing on AAR is explored using scanning electron microscopy (SEM), while the influence of waterproof concrete aggregate and matrix on pore characteristics and hydration products is assessed using nuclear magnetic resonance (NMR) and X-ray diffraction (XRD). The results demonstrate that surface waterproofing with silane and polyvinyl alcohol (PVA) effectively suppress AAR. Moreover, PVA-coated aggregates significantly enhance the compactness of the interfacial transition zone (ITZ) in concrete. Based on these findings, an improved model considering waterproofness is proposed to quantify the degree of alkali aggregate reaction. These findings offer valuable guidance for controlling AAR.

Linear stability analysis of a combustor model with a delayed feedback tube

We conducted a linear stability analysis of a laboratory-scale combustor to develop a delayed feedback method for mitigating combustion oscillations. We employed linearized hydrodynamic equations and a flame transfer function in the frequency domain to assess the stability under various feedback tube configurations, including changes in the length, radius, and connection position. The results of the stability analysis demonstrated a significant improvement in stability when the length of the feedback tube was 0.56 times the wavelength of the unstable mode. Furthermore, the tube radius had an optimal value for stabilizing the system. The connection position also played a crucial role in stability. The effective feedback tube conditions determined in the analysis were applied to a real combustor to demonstrate the successful suppression of oscillations experimentally. The suppression mechanism is discussed using the acoustic power based on the calculation results. The acoustic power profile of the system revealed that the oscillation suppression was not simply an addition of acoustic dissipation, but importantly, a reduction in acoustic power generation at the flame.

Experimental study of NaHCO3/modified vermiculite composite powder for methane explosion suppression

Using a self-constructed experimental platform with 9.5 % methane as the explosive gas, the effects of various masses of NaHCO3, vermiculite, and NaHCO3/modified vermiculite composite powders on the explosion pressure, flame propagation shape, and flame propagation velocity of methane were investigated. The composite powders’ thermal stability and surface microstructure were examined, along with the mechanism of explosion suppression, using thermogravimetric analysis, XRD analysis, and particle size analysis. By comparing various data, 50 wt% NaHCO3/modified vermiculite composite powder with a mass of 360 mg showed the best detonation suppression effect, with Pmax and (dP/dt)max reduced by 53.3 % and 87.1 %, respectively, and Pmax arrival time extended by 142.9 %. The flame disappearance time reached 467 ms, which increased by 165.3 %, and the maximum flame propagation speed decreased by 40 %. Methane explosion suppression is achieved by adding NaHCO3/modified vermiculite composite powder, which prevents flame propagation and breaks the methane explosion chain reaction by chemical and physical suppression of methane explosion.

Endophytic Bacillus velezensis XS142 is an efficient antagonist for Verticillium wilt of potato.

Potato Verticillium wilt (PVW) caused by Verticillium dahliae is a vascular disease, that seriously affects potato (Solanum tuberosum L.) yield and quality worldwide. V. dahliae occupies the vascular bundle and therefore it cannot efficiently be treated with fungicides. Further, the application of these pesticides causes serious environmental problems. Therefore, it is of great importance to find environmentally friendly biological control methods. In this study, bacterial strains were isolated from agricultural lands on which potato had been cultured for 5 years. Five strains with a broad-spectrum antagonistic activity were selected. Among these five strains, Bacillus velezensis XS142 showed the highest antagonistic activity. To study the mechanism of XS142, by which this strain might confer tolerance to V. dahliae in potato, the genome of strain XS142 was sequenced. This showed that its genome has a high level of sequence identity with the model strain B. velezensis FZB42 as the OrthoANI (Average Nucleotide Identity by Orthology) value is 98%. The fungal suppressing mechanisms of this model strain are well studied. Based on the genome comparison it can be predicted that XS142 has the potential to suppress the growth of V. dahliae by production of bacillomycin D, fengycin, and chitinase. Further, the transcriptomes of potatoes treated with XS142 were analyzed and this showed that XS142 does not induce ISR, but the expression of genes encoding peptides with antifungal activity. Here we showed that XS142 is an endophyte. Further, it is isolated from a field where potato had been cultured for several years. These properties give it a high potential to be used, in the future, as a biocontrol agent of PVW in agriculture.

Indirect suppression of CD4 T cell activation through LAG-3-mediated trans-endocytosis of MHC class II

Blockade of immune checkpoint receptors has shown outstanding efficacy for tumor immunotherapy. Promising treatment with anti-lymphocyte-activation gene-3 (LAG-3) has already been recognized as the next efficacious treatment, but there is still limited understanding of the mechanism of LAG-3-mediated immune suppression. Here, utilizing high-resolution molecular imaging, we find a mechanism of CD4 Tcell suppression via LAG-3, in which LAG-3-bound major histocompatibility complex (MHC) class II molecules on antigen-presenting cells (APCs) gather at the central region of an immunological synapse and are trans-endocytosed by Tcell receptor-driven internalization motility toward CD4 and CD8 Tcells expressing LAG-3. Downregulation of MHC class II molecules on APCs thus results in the attenuation of their antigen-presentation function and impairment of CD4 Tcell activation. From these data, anti-LAG-3 treatment is suggested to have potency to directly block the inhibitory signaling via LAG-3 and simultaneously reduce MHC class II expression on APCs by LAG-3-mediated trans-endocytosis for recovery from Tcell exhaustion.

Mechanisms of Short-Circuit Suppression in the bc1 Complex

Mechanisms of Short-Circuit Suppression in the bc1 Complex

Numerical and experimental analysis of biomimetic tubercle for cavitation suppression in viscous oil flow around hydrofoil

This study explores the cavitation suppression mechanisms of biomimetic hydrofoils inspired by whale flipper tubercles, focusing on viscous oil flow around hydrofoils. A novel test system for viscous oil cavitation was developed, featuring a high-speed camera to capture transient cavitation phenomena. The study compared the cavitation behaviour of the flow around a basic blade (Base-blade) with that around a biomimetic blade (Bio-blade) designed with leading-edge tubercles. The visualization results demonstrated that the biomimetic structure significantly reduced the degree and unsteadiness of cavitation. The study also employed a three-dimensional CFD model using the Stress-Blended Eddy Simulation (SBES) method and the Zwart-Gerber-Belamri (ZGB) cavitation mass transfer model to reveal the flow mechanism. The Bio-blade reduced the vapour volume fraction by 9.67%, decreased the drag coefficient (Cd ) by 9.36%, and minimized the lift fluctuations compared to the Base-blade. The biomimetic design reduces the transient shedding cavitation scale, effectively suppressing severe cavitation events. The Bio-blade inhibited the formation of leading-edge separation vortices and reduced the scale of U-shaped vortices that enhance cavitation evolution. In summary, this study provides a comprehensive analysis of the cavitation suppression mechanisms of biomimetic hydrofoils in high-viscosity fluids, offering valuable insights for future research and engineering applications.

Effect of direct water injection on knock suppressing mechanism in a high compression ratio gasoline engine

ABSTRACT A low capacity, boosted gasoline engine is an effective approach to enhancing fuel economy. However, knock combustion poses significant limitations to the practical development of these engines. This study investigated the chemical kinetics and macroscopic properties of engines equipped with direct water injection (DWI) at high compression ratios (CRs) to address knock issues. The results indicated that the generation and consumption pathways of OH and CH2O remain unaffected by water injection. Although water exhibited an opposing effect on the sensitive reactions of OH and CH2O, the production reaction rates of OH and CH2O decrease with water injection. Knock index values at each monitoring point approached zero when the water injection quality exceeds 30%. Additionally, knock suppression effectiveness improved with the advancement of water injection timing. The simulation results indicated that the knock index at high CR decreased from 13.61 to 0.27 when the water/fuel ratio exceeded 30%. The indicated specific fuel consumption decreased by 29.3%, and indicated power increased by 41.8% compared to the original engine. Although NOx and CO emissions increased because of the high CR, the water injection coupled with the compression ratio strategy limited the increase in emissions. These findings indicated that DWI coupled with high CR was advantageous to enhancing fuel economy and reducing emissions in low capacity gasoline engines.