Editorial: Special subject on the mechanical behavior of thermal protection materials and structures

The thermal protection materials and structures are widely used in hypersonic vehicles for the purpose of thermal insulation, and their mechanical behavior is one of the key issues in design and manufacture of hypersonic vehicles. It is our great pleasure to present the seven papers in this special subject of Theoretical ＆ Applied Mechanics Letters （TAML） and introduce the recent progresses on the mechanical behavior of thermal protection materials and structures by the authors.

Protective performance of shear stiffening gel-modified foam against ballistic impact:Experimental and numerical study

As one of the most widely used personal protective equipment(PPE),body armors play an important role in protecting the human body from the high-velocity impact of bullets or projectiles.The body torso and critical organs of the wear may suffer severe behind-armor blunt trauma(BABT)even though the impactor is stopped by the body armor.A type of novel composite material through incorporating shear stiffening gel(STG)into ethylene-vinyl acetate(EVA)foam is developed and used as buffer layers to reduce BABT.In this paper,the protective performance of body armors composed of fabric bulletproof layers and a buffer layer made of foam material is investigated both experimentally and numerically.The effectiveness of STG-modified EVA in damage relief is verified by ballistic tests.In parallel with the experimental study,numerical simulations are conducted by LS-DYNA®to investigate the dynamic response of each component and capture the key mechanical parameters,which are hardly obtained from field tests.To fully describe the material behavior under the transient impact,the selected constitutive models take the failure and strain rate effect into consideration.A good agreement between the experimental observations and numerical results is achieved to prove the validity of the modelling method.The tests and simulations show that the impact-induced deformation on the human body is significantly reduced by using STG-modified EVA as the buffering material.The improvement of protective performance is attributed to better dynamic properties and more outstanding energy absorption capability of the composite foam.

Protective mechanism of quercetin compounds against acrylamide-induced hepatotoxicity

Quercetin compounds have antioxidant,anti-inflammatory and anticancer pharmacological functions.Longterm exposure to acrylamide(AA)can cause liver injury and endanger human health.However,whether quercetin compounds can attenuate AA-induced liver injury and the specific mechanism are not clear.Here,we studied the mechanism and structure-activity relationship of quercetin compounds in reducing AA-induced hepatotoxicity in vivo and in vitro.In vivo studies found that quercetin-like compounds protect against AAinduced liver injury by reducing oxidative stress levels,activating the Akt/m TOR signaling pathway to attenuate autophagy,and improving mitochondrial apoptosis and endoplasmic reticulum stress-mediated apoptosis.In vitro studies found that quercetin compounds protected Hep G2 cells from AA by attenuating the activation of AA-induced autophagy,lowering reactive oxygen species(ROS)levels by exerting antioxidant effects and thus attenuating oxidative stress,increasing mitochondrial membrane potential(MMP),and improving apoptosis-related proteins,thus attenuating AA-induced apoptosis.Furthermore,the conformational differences between quercetin compounds correlated with their protective capacity against AA-induced hepatotoxicity,with quercetin showing the best protective capacity due to its strongest antioxidant activity.In conclusion,quercetin compounds can protect against AA-induced liver injury through multiple pathways of oxidative stress,autophagy and apoptosis,and their protective capacity correlates with antioxidant activity.

Protection behavior of fluorine-containing cover gases on molten magnesium alloys

The sulphur hexa-fluoride gas（SF6）, which is commonly used as the cover gas of molten magnesium alloys in the magnesium industry today, has an extremely high global warming potential（GWP）. The protection mechanism of SF6 containing cover gases on molten magnesium alloys was presented. The cover gas protects the melt by reacting with the melt to form a coherent protective film on the melt surface. The film contains MgO and MgF2. Particles containing MgF2 form on the interface between the oxide film and the bulk magnesium alloy, which correspond to the concave areas from the surface observation. These particles increase the Pilling and Bedworth ratio of surface film and enhance the protective capability of the films. Based on the understanding of the mechanism of SF6, a melting technology in a sealed furnace was proposed, and the protection behavior of magnesium alloys in the sealed melting furnace was investigated under the protective atmosphere containing HFC-134a. The morphology and composition of the surface film were also studied. Experiments to evaluate the protective effect of two other fluorine containing gases with low GWPs on AZglD alloy in the sealed furnace were also carried out, and the results show that the new gases are potential substitutes for SF6.

Antioxidant Protection Mechanisms Reveal Significant Response in Drought-Induced Oxidative Stress in Some Traditional Rice of Assam, India

Drought tolerance levels and antioxidant protection mechanisms were evaluated for 21 traditional rice varieties of Assam, India, along with Sahbhagi Dhan （drought tolerant） and IR64 （drought sensitive） as controls. Drought was imposed in hydroponic culture with polyethylene glycol 6000 （PEG6000） that was initially standardized with different concentrations. All the rice varieties showed apparent decreases in growth characteristics under drought stress （initially at 15% for 7 d followed by 20% PEG6000 for 7 d in Yoshida medium）. On the basis of standard evaluation score （SES）, eight rice varieties showed high drought tolerance which were carried forward for further biochemical analyses. Based on different morpho- physiological parameters, SN03 （Bora）, SN04 （Prosad Bhog）, SN05 （Kola Joha）, SN06 （Helash Bora）, SN08 （Salihoi Bao）, SN12 （Kola Amona）, SN20 （Ronga Bora） and SN21 （Sok-Bonglong） were identified as promising drought tolerant varieties. The non-enzymatic antioxidants activities viz., glutathione, ascorbate and enzymatic antioxidant activities such as superoxide dismutase （SOD）, catalase （CAT）, guaiacol peroxidase （GPX）, ascorbate peroxidase （APX）, glutathione reductase （GR） in shoots and roots of all the selected varieties revealed significant level of protection mechanisms as compared with controls. Enhancement in activities of the overall antioxidant enzymes including SOD, GPX, CAT, GR and APX under drought stress reflects their role in the adaptation process under water stress.

User location privacy protection mechanism for location-based services

With the rapid development of the Internet of Things(IoT),Location-Based Services(LBS)are becoming more and more popular.However,for the users being served,how to protect their location privacy has become a growing concern.This has led to great difficulty in establishing trust between the users and the service providers,hindering the development of LBS for more comprehensive functions.In this paper,we first establish a strong identity verification mechanism to ensure the authentication security of the system and then design a new location privacy protection mechanism based on the privacy proximity test problem.This mechanism not only guarantees the confidentiality of the user s information during the subsequent information interaction and dynamic data transmission,but also meets the service provider's requirements for related data.

Study on Mechanism and Control Effect of Highway Slope Ecological Protection

At present,with the rapid development of social economy,people's awareness of environmental protection continues to increase,and environmental construction and environmental protection work are put on the agenda.Highway slope greening protection is an important means to achieve social sustainable development.Developed countries carried out research earlier in this area,and China's research in this area started later.In engineering construction,ecological protection is to realize slope reinforcement and slope protection depending on the water storage and soil fixation effects of vegetation.Its slope protection can be summarized as the mechanical effect of root system and the hydrological effect of vegetation.As a basic form of slope greening protection,it is necessary for us to understand the mechanism of ecological protection and to enhance the design of ecological protection accordingly.Based on this,the article analyzed the development of slope greening protection technology and ecological protection mechanism from different angles,so as to establish a theoretical framework for future research.

Study on Protection Mechanism of Viscum coloratum (Kom.) Nakai f. lutescens kitag Fruit Polysaccharides on Mice with Acute Alcoholic Liver Injury

This study was conducted to investigate the protective mechanism of V. coloratum fruit polysaccharides（ VCFP） on mice with acute alcoholic liver injury. Acute liver injury model was built by one-time alcohol gavage. The mice were randomly divided into VCFP-treated groups（ low-,medium-,and highdose）,alcohol model group and normal control group at the same time. VCFP-treated groups were administrated polysaccharide intragastrically continuously for4 weeks; and the alcohol model group and normal control group were administrated intragastrically the same amount of normal saline. The general situation and liver tissue morphological structure changes were observed. The results showed that the levels of ALT,AST,TC,TG,MDA contents,and CAT and GSH-Px activity of mice in the model group increased significantly（ P 〈 0. 01）,while the activity of SOD and weight and liver index decreased significantly（ P 〈 0. 01） compared with the normal control group. After 4 weeks of gavage,VCFP could significantly improve weight,liver index and SOD activity,and significantly reduce ALT,AST,TC and TG levels,MDA content and CAT and GSH-Px activity. These results suggest that VCFP can improve antioxidant enzyme activity,remove oxygen free radical and reduce membrane lipid peroxidation reaction,thereby protecting liver cells.

Research on the Environmental Protection Mechanism under the Framework of WTO

WTO, as the most influencing international economic organization, has given rise to some problems worthy of thinking deeply when creating a great trade platform for all countries. For example, the original ecological environment has been destroyed by the development of trade and economy, so that the countries from all over the world are encountering serious environmental crisis. In this paper, the current situation under the new economic environment is introduced first, the environmental protection mechanism in the report of the WTO panel, and also comprehensive countermeasures performed in the new environmental protection mechanism are proposed. Hopefully, this paper can play a help in the further researches.

Persist in Law-based Protection of Human Rights and Improve the Mechanism for the Protection of Human Rights by the Rule of Law

General Secretary Xi Jinping delivered an important speech on China’s Path of Human Rights at a group study session of the Political Bureau of the CPC Central Committee on February 25,2022.Persisting with the law-based protection of human rights and improving the mechanism for the protection of human rights by the rule of law are essential for unswervingly following the development path of human rights in China.The improvement of the mechanism for the protection of human rights by the rule of law necessitates adhering to the principle of respecting the dominant role of the people and removing the institutional obstacles in rule of law protection of human rights;to comprehensively strengthen the implementation of the Constitution,advance the filing and examination of the Constitution,and safeguard the authority of the Constitution;to accelerate the theoretical innovation of human rights and the construction of the discipline system,the academic system and the discourse system of human rights that meet the needs of the new era in China,and to actively participate in and contribute to the global governance on human rights,etc.Improving the mechanism for the protection of human rights by the rule of law can provide a solid protection for people enjoying a better life.

Study of Human Rights Protection Mechanisms for Suspects at the Investigation Stage

When criminal suspects are being investigated for criminal responsibil- ity, they are the most vulnerable to infringement by public power. Thus, they need more special attention and protection. It is the in- evitable requirement of the modern democratic rule of law, and also the inevitable historic choice of respecting and protecting human rights.

Design and test of a protective structure for the double vertical explosive welding of large titanium/steel plate

A comprehensive protective structure with rigidity and flexibility was put forward and designed in view of the quality and safety problems for the double vertical explosive welding of large titanium/steel cladding plate.The movement speed and displacement of the protective structure was calculated by establishing its physics model.The dynamics and stabilization properties were analyzed,and the protective structure parameters were optimized and devised.The comprehensive protective structure,which is composed of rigidity unit and flexibility wall,can bear the impact of detonation wave and the high-speed movement of the cladding plate.There are no damage and deformation in the protective structure and the cladding plate.The protective structure can be used many times.The bonding rate of the Ti/steel plate obtained was nearly 100%,and there is no deformation,surface cracks,and big wave and micro-defects.Therefore,the protective problems of the double vertical explosive welding can be solved effectively by the protective structure.

Neuroprotective effects of naturally sourced bioactive polysaccharides: an update

Polysaccharides are macromolecular complexes that have various biological activities.In vivo and in vitro studies have shown that polysaccharides play neuroprotective roles through multiple mechanisms;consequently,they have potential in the prevention and treatment of neurodegenerative diseases.This paper summarizes related research published during 2015-2020 and reviews advances in the understanding of the neuroprotective effects of bioactive polysaccharides.This review focuses on 15 bioactive polysaccharides from plants and fungi that have neuroprotective properties against oxidative stress,apoptosis,neuroinflammation,and excitatory amino acid toxicity mainly through the regulation of nuclear factor kappa-B,phosphatidylinositol-3-kinase/protein kinase B,mitogen-activated protein kinase,nuclear factor-E2-related factor 2/hemeoxygenase-1,c-jun N-terminal kinase,protein kinase B-mammalian target of rapamycin,and reactive oxygen species-nucleotide-binding oligomerization domain,leucine-rich repeat and pyrin domain-containing 3 signaling pathways.Natural bioactive polysaccharides have potential in the prevention and treatment of neurodegenerative diseases because of their advantageous characteristics,including multi-targeting,low toxicity,and synergistic effects.However,most of the recent related research has focused on cell and animal models.Future randomized clinical trials involving large sample sizes are needed to validate the therapeutic benefits of these neuroprotective polysaccharides in patients having neurodegenerative diseases.

Research progress on ecological protection technology of highway slope: status and challenges

Slope protection has always been a major concern in highway construction and later operation.Ecological protection technology is widely used in highway slope,which takes into account functions of protection,ecology,and landscape.Ecological protection technology is mainly to improve the stability of the slope through the combination of supporting structure and plants,and vegetation restoration can reduce the negative impact of highway construction.In this paper,the latest research progress of ecological protection technology was first reviewed to identify the main construction process and types,which revealed the protection mechanism of ecological protection technology.The comprehensive benefits of ecological slope protection technology were analysed from the aspects of air,water circulation,landscape and biodiversity.It has found that ecological protection technology of highway slope mainly forms the atmosphere-plant-soil system.Ecological protection technology of highway slope improved the stability of the slope through the supporting structure and the anchoring effect of plant roots.And the restoration of the surface vegetation on the slope promoted the photosynthesis and transpiration of plants and purifies the air quality along the highway.Ecological protection technology of highway slope could quickly restore the ecological balance,overall landscape and biodiversity of the region.

Ten golden rules for individualized mechanical ventilation in acute respiratory distress syndrome

Considerable progress has been made over the last decades in the management of acute respiratory distress syndrome(ARDS).Mechanical ventilation(MV)remains the cornerstone of supportive therapy for ARDS.Lung-protective MV minimizes the risk of ventilator-induced lung injury(VILI)and improves survival.Several parame-ters contribute to the risk of VILI and require careful setting including tidal volume(V_(T)),plateau pressure(P_(plat)),driving pressure(ΔP),positive end-expiratory pressure(PEEP),and respiratory rate.Measurement of energy and mechanical power allows quantification of the relative contributions of various parameters(V_(T),P_(plat),ΔP,PEEP,respiratory rate,and airflow)for the individualization of MV settings.The use of neuromuscular blocking agents mainly in cases of severe ARDS can improve oxygenation and reduce asynchrony,although they are not known to confer a survival benefit.Rescue respiratory therapies such as prone positioning,inhaled nitric oxide,and extracorporeal support techniques may be adopted in specific situations.Furthermore,respiratory weaning protocols should also be considered.Based on a review of recent clinical trials,we present 10 golden rules for individualized MV in ARDS management.

Long-term manure application increased soil organic carbon and nitrogen mineralization through accumulation of unprotected and physically protected carbon fractions

Soil organic carbon(SOC)and nitrogen(N)mineralization are important biogeochemical processes associated with soil fertility.These processes are influenced by physically,chemically,and biologically stabilized SOC fractions,the mechanisms of which are not well known.The present study was conducted to evaluate the combined effect of manure and mineral fertilizers on the contents of SOC fractions to promote the mineralization of SOC and N.Treatments included:i)no fertilizer control(CK);ii)a combination of mineral N,phosphorus,and potassium fertilizers(NPK);iii)manure alone(M);iv)manure combined with NPK(MNPK);and v)a high dose of manure combined with NPK(hMNPK).The combined uses of manure and mineral fertilizers(MNPK and hMNPK)enhanced the accumulation of the unprotected coarse particulate organic carbon(C)fraction(cPOC)by 44%-72%compared to CK.Manure applications(M,MNPK and hMNPK)enhanced physically microaggregate-protected organic C(μagg),physicochemically protected organic C within the microaggregate-derived silt(μsilt)fraction(H-μsilt),and physicobiochemically protected organic C within theμsilt fraction(NH-μsilt)by 30%-56%,62%-150%,and 27%-51%,respectively.In contrast,all chemically and biochemically protected SOC fractions showed a minor response to manure application.Accumulation of cPOC,μagg,H-μsilt,and physicochemically protected organic C within the microaggregate-derived clay fraction(H-μclay)significantly contributed to the mineralization of SOC and N,resulting in a significant increase in rice grain yield with long-term manure application.In summary,long-term combined use of manure and mineral fertilizers improved SOC accumulation in unprotected and physically protected fractions,which enhanced SOC and N mineralization and benefited soil productivity in a rice-wheat cropping system.

Active anticorrosion and self-healing coatings:A review with focus on multi-action smart coating strategies

The development of smart coatings with potential for active anticorrosion and self-healing protection of metals is essential for long-term performance of metallic structures in aggressive chemical environments.Presently,emphasis has been placed on the development of advanced smart coatings for corrosion protection in different applications.Innovative multifunctional coatings with fascinating stimuliresponsive functionalities are considered“smart”.The stimuli-responsive functionalities of these smart coatings when properly harnessed result in a class of coatings with inherent autonomous control of corrosion.Fundamentally,when metals are exposed to aggressive environments,occurrences at the metalsolution interface cause environmental changes.These changes can be controlled when triggers from external environment set off active components of smart coating,thereby enhancing coating’s life and functionality.Common triggers include the availability of moisture,concentration of chloride ion,p H gradient,mechanical damage,impact,fatigue,light,redox activity and temperature.In this review,recent technological trends in active anticorrosion and self-healing coatings as functional routes for metal protection are summarized,stimuli responsiveness and mechanisms of inhibition are discussed,and recent multi-action protective systems are particularly focused on.

Nature of cerium on improving low-temperature hydrothermal stability of SAPO-34

To probe the function of Ce on enhancing low-temperature stability of SAPO-34,Ce/SAPO-34 with different Ce contents was prepared via one-pot method and further treated at 70℃in 80%relative humidity for 24 h.The structural results prove that the one-pot synthesis is an effective way to introduce Ce(Ce<0.325 wt%)without influencing micro-structural and chemical composition.The lowtemperature hydrothermal stability of Ce/SAPO-34 is enhanced by Ce loading.More than 92%CHA structure and total acidity are maintained over 0.188 wt%Ce/SAPO-34,while only about 20%of that left on pure H/SAPO-34.As Ce exists as Ce^(3+)at exchange sites on the surface of SAPO-34,the results of the linear relationship between protected surface acidity and structure/acidity conservation manifest that Ce^(3+))effectively hinders the structural collapse.This study provides new insight into surface acidity protection for solving the problem of low-temperature hydrothermal stability of SAPO-34.

The programmed death of fetal oocytes and the correlated surveillance mechanisms

Gamete production is essential for mammalian reproduction.In the ovaries,the primordial follicle,which is the basic reproductive unit,is formed either perinatally or during the second pregnancy stage in humans.However,some oocytes die before the establishment of the primordial follicle pool.Consequently,it is essential to uncover how the size of the primordial follicle pool is determined and how the programmed cell death of oocytes is performed under potential surveillance.According to recent studies,the fate of oocytes in the fetal ovary seems to be determined by different protective strategies through the timely control of apoptosis or autophagy.In this review,we discuss at least three oocyte-derived protective biomarkers,glycogen synthase kinase 3 beta,X-linked inhibitor of apoptosis,and Lysine-specific demethylase 1(also known as KDM1A),responsible for surveilling the developmental quality of fetal oocytes to coordinate primordial follicle formation in the fetal ovary.This review contributes to a better understanding of the secrets of the female reproductive reserve under physiological conditions.