Plant antifreeze proteins(AFPs)are special proteins that can protect plant cells from ice crystal damage in low-temperature environments,and they play a crucial role in the process of plants adapting to cold environ-m...Plant antifreeze proteins(AFPs)are special proteins that can protect plant cells from ice crystal damage in low-temperature environments,and they play a crucial role in the process of plants adapting to cold environ-ments.Proteins with these characteristics have been found infish living in cold regions,as well as many plants and insects.Although research on plant AFPs started relatively late,their application prospects are broad,leading to the attention of many researchers to the isolation,cloning,and genetic improvement of plant AFP genes.Studies have found that the distribution of AFPs in different species seems to be the result of independent evolu-tionary events.Unlike the AFPs found infish and insects,plant AFPs have multiple hydrophilic ice-binding domains,and their recrystallization inhibition activity is about 10–100 times that offish and insect AFPs.Although different plant AFPs have the characteristics of low TH and high RI,their DNA and amino acid sequences are completely different,with small homology.With in-depth research and analysis of the character-istics and mechanisms of plant AFPs,not only has our understanding of plant antifreeze mechanisms been enriched,but it can also be used to improve crop varieties and enhance their freezing tolerance,yield,and quality through genetic engineering.In addition,the study of plant AFPs also contributes to our understanding of freezing resistance mechanisms in other organisms and provides new research directions for thefield of biotech-nology.Therefore,based on the analysis of relevant literature,this article will delve into the concepts,character-istics,research methods,and mechanisms of plant AFPs,summarize the latest research progress and application prospects of AFPs in plant,and provide prospects for the future development of AFP gene research.展开更多
The anti-freezing strategy of hydrogels and their self-healing structure are often contradictory,it is vital to break through the molecular structure to design and construct hydrogels with intrinsic anti-freezing/self...The anti-freezing strategy of hydrogels and their self-healing structure are often contradictory,it is vital to break through the molecular structure to design and construct hydrogels with intrinsic anti-freezing/self-healing for meeting the rapid development of flexible and wearable devices in diverse service conditions.Herein,we design a new hydrogel electrolyte(AF/SH-Hydrogel)with intrinsic anti-freezing/self-healing capabilities by introducing ethylene glycol molecules,dynamic chemical bonding(disulfide bond),and supramolecular interaction(multi-hydrogen bond)into the polyacrylamide molecular chain.Thanks to the exceptional freeze resistance(84%capacity retention at-20℃)and intrinsic self-healing capabilities(95%capacity retention after 5 cutting/self-healing cycles),the obtained AF/SH-Hydrogel makes the zinc||manganese dioxide cell an economically feasible battery for the state-of-the-art applications.The Zn||AF/SH-Hydrogel||MnO_(2)device offers a near-theoretical specific capacity of 285 m A h g^(-1)at 0.1 A g^(-1)(Coulombic efficiency≈100%),as well as good self-healing capability and mechanical flexibility in an ice bath.This work provides insight that can be utilized to develop multifunctional hydrogel electrolytes for application in next generation of self-healable and freeze-resistance smart aqueous energy storage devices.展开更多
This work investigates how functionalization of aluminium surfaces with natural type III Anti-Freeze Protein (AFP) affects the mechanism of heterogeneous ice nucleation. First the bulk ice nucleation properties of d...This work investigates how functionalization of aluminium surfaces with natural type III Anti-Freeze Protein (AFP) affects the mechanism of heterogeneous ice nucleation. First the bulk ice nucleation properties of distilled water and aqueous solution of AFP were evaluated by differential scanning calorimetry. Then the modified surface was characterized by Secondary Ions Mass Spectroscopy (SIMS), Fourier Transform InfraRed (FTIR) spectroscopy and contact angle measurement. Freezing experiments were then conducted in which water droplets underwent a slow controlled cooling. This study shows that compared to uncoated aluminium, the anti-freeze proteins functionalized surfaces exhibit a higher and narrower range of freezing temperature. It was found that these proteins that keep living organisms from freezing in cold environment act in the opposite way once immobilized on surfaces by promoting ice nucleation. Some suggestions regarding the mechanism of action of the observed phenomena were proposed based on the Classical Nucleation Theory (CNT).展开更多
The advance of microelectronics requires the micropower of microsupercapacitors(MSCs) to possess wide temperature-and damage-tolerance beyond high areal energy density.The properties of electrolyte are crucial for MSC...The advance of microelectronics requires the micropower of microsupercapacitors(MSCs) to possess wide temperature-and damage-tolerance beyond high areal energy density.The properties of electrolyte are crucial for MSCs to meet the above requirements.Here,an organohydrogel electrolyte,featured with high salt tolerance,ultralow freezing point,and strong self-healing ability,is experimentally realized via modulating its inner dynamic bonds.Spectroscopic and theoretical analysis reveal that dimethyl sulfoxide has the ability to reconstruct Li^(+)solvation structure,and interact with free water and polyvinyl alcohol chains via forming hydrogen bonds.The organohydrogel electrolyte is employed to build MSCs,which show a boosted energy density,promising wide temperature range-and damage-tolerant ability.These attractive features make the designed organohydrogel electrolyte have great potential to advance MSCs.展开更多
Hydrogel electrolytes hold great potential in flexible zinc ion supercapacitors(ZICs)due to their high conductivity,good safety,and flexibility.However,freezing of electrolytes at low temperature(subzero)leads to dras...Hydrogel electrolytes hold great potential in flexible zinc ion supercapacitors(ZICs)due to their high conductivity,good safety,and flexibility.However,freezing of electrolytes at low temperature(subzero)leads to drastic reduction in ionic conductivity and mechanical properties that deteriorates the performance of flexible ZICs.Besides,the mechanical fracture during arbitrary deformations significantly prunes out the lifespan of the flexible device.Herein,a Zn^(2+)and Li^(+)co-doped,polypyrrole-dopamine decorated Sb_(2)S_(3)incorporated,and polyvinyl alcohol/poly(N-(2-hydroxyethyl)acrylamide)double-network hydrogel electrolyte is constructed with favorable mechanical reliability,anti-freezing,and self-healing ability.In addition,it delivers ultra-high ionic conductivity of 8.6 and 3.7 S m^(-1)at 20 and−30°C,respectively,and displays excellent mechanical properties to withstand tensile stress of 1.85 MPa with tensile elongation of 760%,together with fracture energy of 5.14 MJ m^(-3).Notably,the fractured hydrogel electrolyte can recover itself after only 90 s of infrared illumination,while regaining 83%of its tensile strain and almost 100%of its ionic conductivity during−30–60°C.Moreover,ZICs coupled with this hydrogel electrolyte not only show a wide voltage window(up to 2 V),but also provide high energy density of 230 Wh kg^(-1)at power density of 500 W kg^(-1)with a capacity retention of 86.7%after 20,000 cycles under 20°C.Furthermore,the ZICs are able to retain excellent capacity even under various mechanical deformation at−30°C.This contribution will open up new insights into design of advanced wearable flexible electronics with environmental adaptability and long-life span.展开更多
Solid-state zinc-ion capacitors are emerging as promising candidates for large-scale energy storage owing to improved safety,mechanical and thermal stability and easy-to-direct stacking.Hydrogel electrolytes are appea...Solid-state zinc-ion capacitors are emerging as promising candidates for large-scale energy storage owing to improved safety,mechanical and thermal stability and easy-to-direct stacking.Hydrogel electrolytes are appealing solid-state electrolytes because of eco-friendliness,high conductivity and intrinsic flexibility.However,the electrolyte/electrode interfacial contact and anti-freezing properties of current hydrogel electrolytes are still challenging for practical applications of zinc-ion capacitors.Here,we report a class of hydrogel electrolytes that couple high interfacial adhesion and anti-freezing performance.The synergy of tough hydrogel matrix and chemical anchorage enables a well-adhered interface between hydrogel electrolyte and electrode.Meanwhile,the cooperative solvation of ZnCl2 and LiCl hybrid salts renders the hydrogel electrolyte high ionic conductivity and mechanical elasticity simultaneously at low temperatures.More significantly,the Zn||carbon nanotubes hybrid capacitor based on this hydrogel electrolyte exhibits low-temperature capacitive performance,delivering high-energy density of 39 Wh kg^(-1)at-60°C with capacity retention of 98.7%over 10,000 cycles.With the benefits of the well-adhered electrolyte/electrode interface and the anti-freezing hydrogel electrolyte,the Zn/Li hybrid capacitor is able to accommodate dynamic deformations and function well under 1000 tension cycles even at-60°C.This work provides a powerful strategy for enabling stable operation of low-temperature zinc-ion capacitors.展开更多
The recent advances in aqueous magnesium-ion hybrid supercapacitor(MHSC)have attracted great attention as it brings together the benefits of high energy density,high power density,and synchronously addresses cost and ...The recent advances in aqueous magnesium-ion hybrid supercapacitor(MHSC)have attracted great attention as it brings together the benefits of high energy density,high power density,and synchronously addresses cost and safety issues.However,the freeze of aqueous electrolytes discourages aqueous MHSC from operating at low-temperature conditions.Here,a low-concentration aqueous solution of 4 mol L^(-1) Mg(ClO_(4))_(2) is devised for its low freezing point(-67℃)and ultra-high ionic conductivity(3.37 mS cm^(-1) at-50℃).Both physical characterizations and computational simulations revealed that the Mg(ClO_(4))_(2) can effectively disrupt the original hydrogen bond network among water molecules via transmuting the electrolyte structure,thus yielding a low freezing point.Thus,the Mg(ClO_(4))_(2) electrolytes endue aqueous MHSC with a wider temperature operation range(-50℃–25℃)and a higher energy density of 103.9 Wh kg^(-1) at 3.68 kW kg^(-1) over commonly used magnesium salts(i.e.,MgSO_(4) and Mg(NO_(3))_(2))electrolytes.Furthermore,a quasi-solid-state MHSC based on polyacrylamide-based hydrogel electrolyte holds superior low-temperature performance,excellentflexibility,and high safety.This work pioneers a convenient,cheap,and eco-friendly tactic to procure low-temperature aqueous magnesium-ion energy storage device.展开更多
The influence of anti-freezing admixture on the alkali aggregate reaction in mortar was analyzed with accelerated methods. It is confirmed that the addition of sodium salt ingredients of anti-freezing admixture accele...The influence of anti-freezing admixture on the alkali aggregate reaction in mortar was analyzed with accelerated methods. It is confirmed that the addition of sodium salt ingredients of anti-freezing admixture accelerates the alkali silica reaction to some extent, whereas calcium salt ingredient of anti-freezing admixture reduces the expansion of alkali silica reaction caused by high alkali cement. It is found that the addition of the fly ash considerably suppresses the expansion of alkali silica reaction induced by the anti-freezing admixtures.展开更多
Zinc-ion hybrid supercapacitors(ZHSCs)have been widely considered as promising candidates for flexible electrochemical energy storage devices.The key challenge is to develop hydrogel electrolytes with high hydrophilic...Zinc-ion hybrid supercapacitors(ZHSCs)have been widely considered as promising candidates for flexible electrochemical energy storage devices.The key challenge is to develop hydrogel electrolytes with high hydrophilicity,anti-freezing,bending resistance,and stable interface with electrodes.This study reported a hydrogel electrolyte system that can meet the above functions,in which the zincophilic and negatively charged SO3−,migratable Na+,abundant hydrophilic functional groups,gum xanthan,and porous architecture could effectively promote the electrochemical performance of ZHSCs.ZHSCs with such hydrogel electrolytes not only exhibited good low-temperature performance but also showed excellent bending resistance ability.A high specific capacitance could be kept after a long air-working lifespan over 10,000 cycles under a wide operation voltage of 1.85 V at−10℃.Furthermore,flexible ZHSCs could maintain the capacitance retention of 93.18%even after continuous 500 bends at an angle of 180°.The designed hydrogel electrolytes could be also used for other electrochemical energy storage devices with anti-freezing and bending resistance by changing electrolyte salt.展开更多
Soft strain sensors that can transduce stretch stimuli into electrical readouts are promising as sustainable wearable electronics.However,most strain sensors cannot achieve highly-sensitive and wide-range detection of...Soft strain sensors that can transduce stretch stimuli into electrical readouts are promising as sustainable wearable electronics.However,most strain sensors cannot achieve highly-sensitive and wide-range detection of ultralow and high strains.Inspired by bamboo structures,anti-freezing microfibers made of conductive poly(vinyl alcohol)hydrogel with poly(3,4-ethylenedioxythiphene)-poly(styrenesulfonate)are developed via continuous microfluidic spinning.The microfibers provide unique bamboo-like structures with enhanced local stress to improve both their length change and resistance change upon stretching for efficient signal conversion.The microfibers allow highlysensitive(detection limit:0.05%strain)and wide-range(0%-400%strain)detection of ultralow and high strains,as well as features of good stretchability(485%strain)and anti-freezing property(freezing temperature:-41.1°C),fast response(200 ms),and good repeatability.The experimental results,together with theoretical foundation analysis and finite element analysis,prove their enhanced length and resistance changes upon stretching for efficient signal conversion.By integrating microfluidic spinning with 3D-printing technique,the textiles of the microfibers can be flexibly constructed.The microfibers and their 3D-printed textiles enable highperformance monitoring of human motions including finger bending and throat vibrating during phonation.This work provides an efficient and general strategy for developing advanced conductive hydrogel microfibers as highperformance wearable strain sensors.展开更多
The auxiliary shaft is an important location for coal mine heating in the winter, where the main purpose of heating is to prevent icing of the shaft. Wellhead heating requires characteristics of openness, no-noise and...The auxiliary shaft is an important location for coal mine heating in the winter, where the main purpose of heating is to prevent icing of the shaft. Wellhead heating requires characteristics of openness, no-noise and big heat loads. The original coal-fired boiler heating mode causes significant waste of energy and environmental pollution due to the low efficiency of the heat exchange. Therefore, to solve these prob- lems, we will use deep mine geothermal energy to heat the wellhead by making full use of its negative pressure field and design a low-temperature water and fan-free heating system. Through numerical cal- culations we will simulate temperature fields, pressure fields and velocity fields under different air sup- ply temperatures, as well as different air supply outlet locations and varying number of radiators in the wellhead room of a new auxiliary shaft to find the proper layout and number of radiators that meet well- head anti-frost requirements from our simulation results, in order to provide guidelines for a practical engineering design. Tests on the Zhangshuanglou auxiliary shaft wellhead shows good, look promising and appear to resolve successfully the problem of high energy consumption and high pollution of well- head heating by a coal-fired boiler.展开更多
In order to analyze the microstructure of salt anti-freezing asphalt concrete, i e, MFL(Mafilon) modified asphalt concrete, MIP(mercury intrusion porosity) method was used to obtain the data including porosity and...In order to analyze the microstructure of salt anti-freezing asphalt concrete, i e, MFL(Mafilon) modified asphalt concrete, MIP(mercury intrusion porosity) method was used to obtain the data including porosity and pore size distribution in micro scale. Results show that the porosity grows up with the increase of immersion duration and the salt content. During the immersion, the amount of large pores(60-200 μm) grow up gradually and porosity also grows up correspondingly. Even with different immersion duration, most pores' size distribute is beyond 7000 nm.展开更多
The complexity of application environment stimulates the development of wearable devices based on functional hydrogels.Among all the promising performances,self-healing and self-adhesion properties are ideal for hydro...The complexity of application environment stimulates the development of wearable devices based on functional hydrogels.Among all the promising performances,self-healing and self-adhesion properties are ideal for hydrogel sensors,which can guarantee good accuracy,comfort and long service life.However,it is still a challenge to achieve simultaneous self-healing and self-adhesion in different environments(in the air,underwater and at low temperatures).Herein,a feasible new strategy was successfully carried out to prepare a starch-based composite conductive organohydrogel based on the reversible borate ester bonds formed by complexing starch/polyvinyl alcohol(PVA)/tea polyphenol(TP)with borax,and multiple hydrogen-bond interactions among PVA,starch,TP and ethylene glycol(EG).Silver nanoparticles(Ag-NPs),reduced and stabilized by TP,and MWCNTs(multi-walled carbon nanotubes)were introduced into the cross-linking networks to endow the resulting PBSTCE organohydrogel with considerable antibacterial property and conductivity,respectively.The organohydrogel possessed rapid self-healing(HE(self-healing efficiency)=96.07%in 90 s,both in the air and underwater,also at-20℃),considerable self-adhesion(both in the air and underwater,also at-20℃),remarkable stretchability(814%of elongation),anti-freezing(-20℃)and moisture-retention abilities,antibacterial activity,sensitive pH/sugar-responsiveness,and plasticity.The strain sensor formed by the PBSTCE organohydrogel can not only effectively record large-scale human motions(e.g.finger/wrist/elbow bending,walking,etc.),but also accurately capture subtle motion changes(e.g.breathing,chewing,swallowing,speaking,smiling and frowning).Moreover,the self-healed organohydrogel sensor also exhibited almost invariable mechanical,electrical and sensing behaviors.This work demonstrates a feasible strategy to construct multifunctional starch-based organohy-drogels,and promotes their efficient,stable and eco-friendly application as flexible wearable devices.展开更多
Aqueous zinc-ion batteries(ZIBs)have attracted immense attention for flexible energy storage devices due to their high safety and low cost.However,conventional flexible aqueous ZIBs will undergo severe capacity loss a...Aqueous zinc-ion batteries(ZIBs)have attracted immense attention for flexible energy storage devices due to their high safety and low cost.However,conventional flexible aqueous ZIBs will undergo severe capacity loss at subzero temperature due to the inevitably freeze of electrolytes.In addition,under large bending or stretching strains,the encapsulation of devices would be damaged,which causes the evaporation of water in electrolytes and results in device failure.Herein,an anti-freezing and anti-drying gel electrolyte based on polyacrylamide(PAM)and glycerol(Gly)is developed.The strong hydrogen-bonding interactions between PAM or Gly and water molecules not only avoid the crystallization of the gel electrolyte at low temperatures,but also constrain the free water and restrict its evaporation.Therefore,such gel electrolyte displays a high ionic conductivity of 9.65×10^(−5)S cm^(−1)at−40℃.Furthermore,it can restrict the dehydration process when the electrolyte is exposed to ambient environment.The flexible ZIBs based on such gel electrolyte exhibit excellent electrochemical performance at−40℃and the devices without encapsulation retain 98%of their initial capacity in ambient condition after 30 days.This work provides a route to design anti-freezing and anti-drying gel electrolytes for aqueous energy storage devices.展开更多
Layered double hydroxides(LDHs)are promising electrode candidates for supercapacitors.However,lim-itations like inferior cycling stability and unsatisfactory charge storage capability at low temperatures have exerted ...Layered double hydroxides(LDHs)are promising electrode candidates for supercapacitors.However,lim-itations like inferior cycling stability and unsatisfactory charge storage capability at low temperatures have exerted negative effects on their applications.Herein,a novel synthetic process has been elaborately designed and provided to have the composition and structure of the C/N-NiCoMn-LDH/Ag(C/N-CNMA)delicately regulated.Both the experimental and theoretical researches unveil that the incorporated manganese species and elemental silver could dramatically modulate the bandgap,crystallinity and surface electron structure of the LDH,leading to the remarkable improvement in its conductivity,exposed active sites and intrinsic electrochemical activity,and thus the OH^(*)and O^(*)adsorption free energy could be remarkably optimized,even at low temperatures.In addition,the low crystallinity C/N-CNMA is of great electrochemical compatibility with both the KOH aqueous electrolyte and the isobutyl alcohol(IPA)modulated organohydrogel electrolyte.By means of adjusting the solvation and hydrogen bonding in the electrolytes,the assembled hybrid supercapacitors deliver excellent energy density,power density and cycling stability in the temperature range of-30 to 25℃.Specifically,the gel electrolyte with IPA as the anti-freezing functional additive displays high flexibility and ionic conductivity at low temperatures.展开更多
It remains a great challenge to balance the kinetic stability and intrinsic healing ability of polymer materials.Here,we present an efficient strategy of using a synthetic reaction cycle to regulate the intrinsic heal...It remains a great challenge to balance the kinetic stability and intrinsic healing ability of polymer materials.Here,we present an efficient strategy of using a synthetic reaction cycle to regulate the intrinsic healing ability of thermodynamically stable and kinetically inert multifunctional organohydrogels.By combining a double decomposition reaction with spontaneous energy dissipation,we can construct the simplest synthetic reaction cycle that can induce a transient out-of-equilibrium state for achieving the healing of organohydrogels with kinetically locked acylhydrazone bonds.In addition to balancing kinetic stability and healing ability,the synthetic reaction cycle also enables the polymer materials to have high tolerance to organic solvents,high ionic strength,high and low temperatures,and other harsh conditions.Therefore,the kinetically stable and healable organohydrogels remain mechanically flexible and electrically conductive even down to−40°C and are readily recyclable.The integration of chemical networks into healable polymers may provide novel,versatile materials for building next-generation electronic devices.展开更多
The challenges of enabling zinc air batteries to operate at ultralow temperatures are twofold.The Prerequisite is preventing the electrolyte from freezing while maintaining high ionic conductivity.Secondly,the catalys...The challenges of enabling zinc air batteries to operate at ultralow temperatures are twofold.The Prerequisite is preventing the electrolyte from freezing while maintaining high ionic conductivity.Secondly,the catalyst has to work efficiently at low temperatures.This highlight presents the latest development to resolve the challenges by tuning the structures of the electrolyte and catalyst,offering a new paradigm to widen the working temperature range of zinc air batteries.展开更多
Hydrogel electrolytes with anti-freezing properties are crucial for flexible quasi-solid-state supercapacitors operating at low temperatures.However,the electrolyte freezing and sluggish ion migration caused by the co...Hydrogel electrolytes with anti-freezing properties are crucial for flexible quasi-solid-state supercapacitors operating at low temperatures.However,the electrolyte freezing and sluggish ion migration caused by the cold temperature inevitably damage the flexibility and electrochemical properties of supercapacitors.Herein,we introduce the concentrated electrolyte into a freezecasted poly(vinyl alcohol)hydrogel film not only reducing the freezing point of the electrolyte(−51.14℃)in gels for ensuring the flexibility,but also improving the ionic conductivity of the hydrogel electrolyte(5.92 mS cm^(−1)at−40℃)at low temperatures.As a proof,an all-in-one supercapacitor,synthesized by the one-step polymerization method,exhibits a good specific capacitance of 278.6 mF cm^(−2)at−40℃(accounting for 93.8%of the capacitance at room temperature),high rate performance(50%retention under the 100-fold increase in current densities),and long cycle life(88.9%retention after 8,000 cycles at−40℃),representing an excellent low-temperature performance.Our results provide a fresh insight into the hydrogel electrolyte design for flexible energy storage devices operating in the wide range of temperature and open up an exciting direction for improving all-in-one supercapacitors.展开更多
Although significant progress has been achieved in developing high energy aqueous zinc ion hybrid supercapacitors(ZHSCs),the sluggish diffusion of zinc ion(Zn^(2+))and unsatisfactory cathodes still hinder their energy...Although significant progress has been achieved in developing high energy aqueous zinc ion hybrid supercapacitors(ZHSCs),the sluggish diffusion of zinc ion(Zn^(2+))and unsatisfactory cathodes still hinder their energy density and cycling life span.This work demonstrates the use of nitrogen-doped mesoporous carbon nanospheres(NMCSs)with appropriately hierarchical pore distribution and enhanced zinc ion storage capability for efficient Zn^(2+)storage.The asprepared aqueous ZHSC delivers a significant specific capacity of 157.8 mA h g^(-1),a maximum energy density of 126.2 W h kg^(-1) at 0.2 A g^(-1),and an ultra-high power density of 39.9 kW kg^(-1) with a quick charge time of 5.5 s.Furthermore,the ZHSC demonstrates an ultra-long cycling life span of 50,000 cycles with an exciting capacity retention of 96.2%.More interestingly,a new type of planar ZHSC is fabricated with outstanding low-temperature electrochemical performance,landmark volumetric energy density of 31.6 mW h cm^(-3),and excellent serial and parallel integration.Mechanism investigation verifies that the superior electrochemical capability is due to the synergistic effect of cation and anion adsorption,as well as the reversible chemical adsorption of NMCSs.This work provides not only an innovative strategy to construct and develop novel high-performance ZHSCs,but also a deeper understanding of the electrochemical characteristics of ZHSCs.展开更多
基金funded by the Fundamental Research Funds for the Central Universities under Grant No.BFUKF202309Special Scientific Research Fund of Talents Introduced into Hebei Agricultural University under Grant No.YJ2022025+1 种基金Basic Scientific Research Projects of Provincial Universities in Hebei Province under Grant No.KY202203Hebei Agriculture Research System under Grant No.HBCT2024200101,S&T Program of Hebei under Grant No.21326301D.
文摘Plant antifreeze proteins(AFPs)are special proteins that can protect plant cells from ice crystal damage in low-temperature environments,and they play a crucial role in the process of plants adapting to cold environ-ments.Proteins with these characteristics have been found infish living in cold regions,as well as many plants and insects.Although research on plant AFPs started relatively late,their application prospects are broad,leading to the attention of many researchers to the isolation,cloning,and genetic improvement of plant AFP genes.Studies have found that the distribution of AFPs in different species seems to be the result of independent evolu-tionary events.Unlike the AFPs found infish and insects,plant AFPs have multiple hydrophilic ice-binding domains,and their recrystallization inhibition activity is about 10–100 times that offish and insect AFPs.Although different plant AFPs have the characteristics of low TH and high RI,their DNA and amino acid sequences are completely different,with small homology.With in-depth research and analysis of the character-istics and mechanisms of plant AFPs,not only has our understanding of plant antifreeze mechanisms been enriched,but it can also be used to improve crop varieties and enhance their freezing tolerance,yield,and quality through genetic engineering.In addition,the study of plant AFPs also contributes to our understanding of freezing resistance mechanisms in other organisms and provides new research directions for thefield of biotech-nology.Therefore,based on the analysis of relevant literature,this article will delve into the concepts,character-istics,research methods,and mechanisms of plant AFPs,summarize the latest research progress and application prospects of AFPs in plant,and provide prospects for the future development of AFP gene research.
基金supported by the link project of the National Natural Science Foundation of China(52002052 and 22209020)the Key Research and Development Project of Science and Technology Department of Sichuan Province(2022YFSY0004)+2 种基金the Opening project of the State Key Laboratory of New Textile Materials and Advanced Processing Technology(FZ2021009)the Natural Science Foundation of Sichuan Province(2023NSFSC0995)the Natural Science Foundation of Hunan Province(2022JJ30227)。
文摘The anti-freezing strategy of hydrogels and their self-healing structure are often contradictory,it is vital to break through the molecular structure to design and construct hydrogels with intrinsic anti-freezing/self-healing for meeting the rapid development of flexible and wearable devices in diverse service conditions.Herein,we design a new hydrogel electrolyte(AF/SH-Hydrogel)with intrinsic anti-freezing/self-healing capabilities by introducing ethylene glycol molecules,dynamic chemical bonding(disulfide bond),and supramolecular interaction(multi-hydrogen bond)into the polyacrylamide molecular chain.Thanks to the exceptional freeze resistance(84%capacity retention at-20℃)and intrinsic self-healing capabilities(95%capacity retention after 5 cutting/self-healing cycles),the obtained AF/SH-Hydrogel makes the zinc||manganese dioxide cell an economically feasible battery for the state-of-the-art applications.The Zn||AF/SH-Hydrogel||MnO_(2)device offers a near-theoretical specific capacity of 285 m A h g^(-1)at 0.1 A g^(-1)(Coulombic efficiency≈100%),as well as good self-healing capability and mechanical flexibility in an ice bath.This work provides insight that can be utilized to develop multifunctional hydrogel electrolytes for application in next generation of self-healable and freeze-resistance smart aqueous energy storage devices.
文摘This work investigates how functionalization of aluminium surfaces with natural type III Anti-Freeze Protein (AFP) affects the mechanism of heterogeneous ice nucleation. First the bulk ice nucleation properties of distilled water and aqueous solution of AFP were evaluated by differential scanning calorimetry. Then the modified surface was characterized by Secondary Ions Mass Spectroscopy (SIMS), Fourier Transform InfraRed (FTIR) spectroscopy and contact angle measurement. Freezing experiments were then conducted in which water droplets underwent a slow controlled cooling. This study shows that compared to uncoated aluminium, the anti-freeze proteins functionalized surfaces exhibit a higher and narrower range of freezing temperature. It was found that these proteins that keep living organisms from freezing in cold environment act in the opposite way once immobilized on surfaces by promoting ice nucleation. Some suggestions regarding the mechanism of action of the observed phenomena were proposed based on the Classical Nucleation Theory (CNT).
基金National Natural Science Foundation of China(52072297 and 51907149)Key R&D Plan of Shaanxi Province(2021GXLH-Z-068)+1 种基金China Postdoctoral Science Foundation(2019M653609)the Young Talent Support Plan of Xi’an Jiaotong University。
文摘The advance of microelectronics requires the micropower of microsupercapacitors(MSCs) to possess wide temperature-and damage-tolerance beyond high areal energy density.The properties of electrolyte are crucial for MSCs to meet the above requirements.Here,an organohydrogel electrolyte,featured with high salt tolerance,ultralow freezing point,and strong self-healing ability,is experimentally realized via modulating its inner dynamic bonds.Spectroscopic and theoretical analysis reveal that dimethyl sulfoxide has the ability to reconstruct Li^(+)solvation structure,and interact with free water and polyvinyl alcohol chains via forming hydrogen bonds.The organohydrogel electrolyte is employed to build MSCs,which show a boosted energy density,promising wide temperature range-and damage-tolerant ability.These attractive features make the designed organohydrogel electrolyte have great potential to advance MSCs.
基金supported by the National Natural Science Foundation of China(52174247 and 22302066)“Hejian”Innovative Talent Project of Hunan Province(No.2022RC1088)+1 种基金the Hunan Provincial Natural Science Foundation(2023JJ40255)the Scientific Research Foundation of Hunan Provincial Education(22B0599 and 23A0442)。
文摘Hydrogel electrolytes hold great potential in flexible zinc ion supercapacitors(ZICs)due to their high conductivity,good safety,and flexibility.However,freezing of electrolytes at low temperature(subzero)leads to drastic reduction in ionic conductivity and mechanical properties that deteriorates the performance of flexible ZICs.Besides,the mechanical fracture during arbitrary deformations significantly prunes out the lifespan of the flexible device.Herein,a Zn^(2+)and Li^(+)co-doped,polypyrrole-dopamine decorated Sb_(2)S_(3)incorporated,and polyvinyl alcohol/poly(N-(2-hydroxyethyl)acrylamide)double-network hydrogel electrolyte is constructed with favorable mechanical reliability,anti-freezing,and self-healing ability.In addition,it delivers ultra-high ionic conductivity of 8.6 and 3.7 S m^(-1)at 20 and−30°C,respectively,and displays excellent mechanical properties to withstand tensile stress of 1.85 MPa with tensile elongation of 760%,together with fracture energy of 5.14 MJ m^(-3).Notably,the fractured hydrogel electrolyte can recover itself after only 90 s of infrared illumination,while regaining 83%of its tensile strain and almost 100%of its ionic conductivity during−30–60°C.Moreover,ZICs coupled with this hydrogel electrolyte not only show a wide voltage window(up to 2 V),but also provide high energy density of 230 Wh kg^(-1)at power density of 500 W kg^(-1)with a capacity retention of 86.7%after 20,000 cycles under 20°C.Furthermore,the ZICs are able to retain excellent capacity even under various mechanical deformation at−30°C.This contribution will open up new insights into design of advanced wearable flexible electronics with environmental adaptability and long-life span.
基金This work was supported by the Natural Science Foundation of Jiangsu Province(BK20220213)the Fundamental Research Funds of Jiangsu Key Laboratory of Biomass Energy and Material(JSBEM-S-202210 and JSBEM-S-202102).
文摘Solid-state zinc-ion capacitors are emerging as promising candidates for large-scale energy storage owing to improved safety,mechanical and thermal stability and easy-to-direct stacking.Hydrogel electrolytes are appealing solid-state electrolytes because of eco-friendliness,high conductivity and intrinsic flexibility.However,the electrolyte/electrode interfacial contact and anti-freezing properties of current hydrogel electrolytes are still challenging for practical applications of zinc-ion capacitors.Here,we report a class of hydrogel electrolytes that couple high interfacial adhesion and anti-freezing performance.The synergy of tough hydrogel matrix and chemical anchorage enables a well-adhered interface between hydrogel electrolyte and electrode.Meanwhile,the cooperative solvation of ZnCl2 and LiCl hybrid salts renders the hydrogel electrolyte high ionic conductivity and mechanical elasticity simultaneously at low temperatures.More significantly,the Zn||carbon nanotubes hybrid capacitor based on this hydrogel electrolyte exhibits low-temperature capacitive performance,delivering high-energy density of 39 Wh kg^(-1)at-60°C with capacity retention of 98.7%over 10,000 cycles.With the benefits of the well-adhered electrolyte/electrode interface and the anti-freezing hydrogel electrolyte,the Zn/Li hybrid capacitor is able to accommodate dynamic deformations and function well under 1000 tension cycles even at-60°C.This work provides a powerful strategy for enabling stable operation of low-temperature zinc-ion capacitors.
基金supported by Shenzhen Science and Technology Innovation Committee(Nos.JCYJ20190806145609284,GJHZ20190820091203667,JSGG20201102161000002,SGD-X20201103095607022)Guangdong Basic and Applied Basic Research Foundation(2020A1515010716)+1 种基金Guangdong Introducing Innovative and Entrepreneurial Teams Program(2019ZT08Z656)P.H.would like to acknowledge Shenzhen Science and Technology Program(KQTD20190929172522-248).
文摘The recent advances in aqueous magnesium-ion hybrid supercapacitor(MHSC)have attracted great attention as it brings together the benefits of high energy density,high power density,and synchronously addresses cost and safety issues.However,the freeze of aqueous electrolytes discourages aqueous MHSC from operating at low-temperature conditions.Here,a low-concentration aqueous solution of 4 mol L^(-1) Mg(ClO_(4))_(2) is devised for its low freezing point(-67℃)and ultra-high ionic conductivity(3.37 mS cm^(-1) at-50℃).Both physical characterizations and computational simulations revealed that the Mg(ClO_(4))_(2) can effectively disrupt the original hydrogen bond network among water molecules via transmuting the electrolyte structure,thus yielding a low freezing point.Thus,the Mg(ClO_(4))_(2) electrolytes endue aqueous MHSC with a wider temperature operation range(-50℃–25℃)and a higher energy density of 103.9 Wh kg^(-1) at 3.68 kW kg^(-1) over commonly used magnesium salts(i.e.,MgSO_(4) and Mg(NO_(3))_(2))electrolytes.Furthermore,a quasi-solid-state MHSC based on polyacrylamide-based hydrogel electrolyte holds superior low-temperature performance,excellentflexibility,and high safety.This work pioneers a convenient,cheap,and eco-friendly tactic to procure low-temperature aqueous magnesium-ion energy storage device.
文摘The influence of anti-freezing admixture on the alkali aggregate reaction in mortar was analyzed with accelerated methods. It is confirmed that the addition of sodium salt ingredients of anti-freezing admixture accelerates the alkali silica reaction to some extent, whereas calcium salt ingredient of anti-freezing admixture reduces the expansion of alkali silica reaction caused by high alkali cement. It is found that the addition of the fly ash considerably suppresses the expansion of alkali silica reaction induced by the anti-freezing admixtures.
基金The financial support from National Natural Science Foundation of China(2210910352205489,and 21875144)Shenzhen Science and Technology Research Grant(JCYJ20200109105003940)is gratefully acknowledged.
文摘Zinc-ion hybrid supercapacitors(ZHSCs)have been widely considered as promising candidates for flexible electrochemical energy storage devices.The key challenge is to develop hydrogel electrolytes with high hydrophilicity,anti-freezing,bending resistance,and stable interface with electrodes.This study reported a hydrogel electrolyte system that can meet the above functions,in which the zincophilic and negatively charged SO3−,migratable Na+,abundant hydrophilic functional groups,gum xanthan,and porous architecture could effectively promote the electrochemical performance of ZHSCs.ZHSCs with such hydrogel electrolytes not only exhibited good low-temperature performance but also showed excellent bending resistance ability.A high specific capacitance could be kept after a long air-working lifespan over 10,000 cycles under a wide operation voltage of 1.85 V at−10℃.Furthermore,flexible ZHSCs could maintain the capacitance retention of 93.18%even after continuous 500 bends at an angle of 180°.The designed hydrogel electrolytes could be also used for other electrochemical energy storage devices with anti-freezing and bending resistance by changing electrolyte salt.
基金support from the National Natural Science Foundation of China(Nos.22278281 and 21991101)Sichuan University(2020SCUNG112)
文摘Soft strain sensors that can transduce stretch stimuli into electrical readouts are promising as sustainable wearable electronics.However,most strain sensors cannot achieve highly-sensitive and wide-range detection of ultralow and high strains.Inspired by bamboo structures,anti-freezing microfibers made of conductive poly(vinyl alcohol)hydrogel with poly(3,4-ethylenedioxythiphene)-poly(styrenesulfonate)are developed via continuous microfluidic spinning.The microfibers provide unique bamboo-like structures with enhanced local stress to improve both their length change and resistance change upon stretching for efficient signal conversion.The microfibers allow highlysensitive(detection limit:0.05%strain)and wide-range(0%-400%strain)detection of ultralow and high strains,as well as features of good stretchability(485%strain)and anti-freezing property(freezing temperature:-41.1°C),fast response(200 ms),and good repeatability.The experimental results,together with theoretical foundation analysis and finite element analysis,prove their enhanced length and resistance changes upon stretching for efficient signal conversion.By integrating microfluidic spinning with 3D-printing technique,the textiles of the microfibers can be flexibly constructed.The microfibers and their 3D-printed textiles enable highperformance monitoring of human motions including finger bending and throat vibrating during phonation.This work provides an efficient and general strategy for developing advanced conductive hydrogel microfibers as highperformance wearable strain sensors.
基金the National Basic Research Program of China (No.2006CB202200)the National Major Project of the Ministry of Education (No. 304005)the Program for Changjiang Scholars and Innovative Research Team in University of China (No. IRT0656)
文摘The auxiliary shaft is an important location for coal mine heating in the winter, where the main purpose of heating is to prevent icing of the shaft. Wellhead heating requires characteristics of openness, no-noise and big heat loads. The original coal-fired boiler heating mode causes significant waste of energy and environmental pollution due to the low efficiency of the heat exchange. Therefore, to solve these prob- lems, we will use deep mine geothermal energy to heat the wellhead by making full use of its negative pressure field and design a low-temperature water and fan-free heating system. Through numerical cal- culations we will simulate temperature fields, pressure fields and velocity fields under different air sup- ply temperatures, as well as different air supply outlet locations and varying number of radiators in the wellhead room of a new auxiliary shaft to find the proper layout and number of radiators that meet well- head anti-frost requirements from our simulation results, in order to provide guidelines for a practical engineering design. Tests on the Zhangshuanglou auxiliary shaft wellhead shows good, look promising and appear to resolve successfully the problem of high energy consumption and high pollution of well- head heating by a coal-fired boiler.
基金Funded by the National Natural Science Foundation of China(No.51578290)
文摘In order to analyze the microstructure of salt anti-freezing asphalt concrete, i e, MFL(Mafilon) modified asphalt concrete, MIP(mercury intrusion porosity) method was used to obtain the data including porosity and pore size distribution in micro scale. Results show that the porosity grows up with the increase of immersion duration and the salt content. During the immersion, the amount of large pores(60-200 μm) grow up gradually and porosity also grows up correspondingly. Even with different immersion duration, most pores' size distribute is beyond 7000 nm.
基金This work is financed by the National Natural Science Founda-tion of China(No.21978180).We appreciate the valuable help of Dr.Jinwei Zhang from the College of Biomass Science and Engineering of Sichuan University and Hui Wang from the Analytical&Testing Center of Sichuan University.We thank eceshi(www.eceshi.com)for the great help in SEM analysis.
文摘The complexity of application environment stimulates the development of wearable devices based on functional hydrogels.Among all the promising performances,self-healing and self-adhesion properties are ideal for hydrogel sensors,which can guarantee good accuracy,comfort and long service life.However,it is still a challenge to achieve simultaneous self-healing and self-adhesion in different environments(in the air,underwater and at low temperatures).Herein,a feasible new strategy was successfully carried out to prepare a starch-based composite conductive organohydrogel based on the reversible borate ester bonds formed by complexing starch/polyvinyl alcohol(PVA)/tea polyphenol(TP)with borax,and multiple hydrogen-bond interactions among PVA,starch,TP and ethylene glycol(EG).Silver nanoparticles(Ag-NPs),reduced and stabilized by TP,and MWCNTs(multi-walled carbon nanotubes)were introduced into the cross-linking networks to endow the resulting PBSTCE organohydrogel with considerable antibacterial property and conductivity,respectively.The organohydrogel possessed rapid self-healing(HE(self-healing efficiency)=96.07%in 90 s,both in the air and underwater,also at-20℃),considerable self-adhesion(both in the air and underwater,also at-20℃),remarkable stretchability(814%of elongation),anti-freezing(-20℃)and moisture-retention abilities,antibacterial activity,sensitive pH/sugar-responsiveness,and plasticity.The strain sensor formed by the PBSTCE organohydrogel can not only effectively record large-scale human motions(e.g.finger/wrist/elbow bending,walking,etc.),but also accurately capture subtle motion changes(e.g.breathing,chewing,swallowing,speaking,smiling and frowning).Moreover,the self-healed organohydrogel sensor also exhibited almost invariable mechanical,electrical and sensing behaviors.This work demonstrates a feasible strategy to construct multifunctional starch-based organohy-drogels,and promotes their efficient,stable and eco-friendly application as flexible wearable devices.
基金supported by the Natural Science Foundation of Tianjin(18JCJQJC46300 and 19JCZDJC31900)the National Natural Science Foundation of China(51822205 and 21875121)+2 种基金the Ministry of Science and Technology of China(2019YFA0705600 and 2017YFA0206701)the Ministry of Education of China(B12015)the"Frontiers Science Center for New Organic Matter",Nankai University(63181206)。
文摘Aqueous zinc-ion batteries(ZIBs)have attracted immense attention for flexible energy storage devices due to their high safety and low cost.However,conventional flexible aqueous ZIBs will undergo severe capacity loss at subzero temperature due to the inevitably freeze of electrolytes.In addition,under large bending or stretching strains,the encapsulation of devices would be damaged,which causes the evaporation of water in electrolytes and results in device failure.Herein,an anti-freezing and anti-drying gel electrolyte based on polyacrylamide(PAM)and glycerol(Gly)is developed.The strong hydrogen-bonding interactions between PAM or Gly and water molecules not only avoid the crystallization of the gel electrolyte at low temperatures,but also constrain the free water and restrict its evaporation.Therefore,such gel electrolyte displays a high ionic conductivity of 9.65×10^(−5)S cm^(−1)at−40℃.Furthermore,it can restrict the dehydration process when the electrolyte is exposed to ambient environment.The flexible ZIBs based on such gel electrolyte exhibit excellent electrochemical performance at−40℃and the devices without encapsulation retain 98%of their initial capacity in ambient condition after 30 days.This work provides a route to design anti-freezing and anti-drying gel electrolytes for aqueous energy storage devices.
基金supported by the Science Foundation for Excellent Youth of Henan Province(202300410166)the Science and Technology Project of Henan Province(212102210201 and 212102310015)+3 种基金China Postdoctoral Science Foundation(2020M672179)the Key Project of Science and Technology Research of Henan Provincial Department of Education(21A430017)the Training Program for Young Backbone Teachers in the University of Henan Province(2020GGJS052)the Major Project of WIUCAS(WIUCASQD2021004 and WIUCASQD2021035)。
基金supported by the National Natural Science Foundation of China (Nos.51972049 and 51672040)the Jilin Province Development and Reform Commission (No.2021C040-4).
文摘Layered double hydroxides(LDHs)are promising electrode candidates for supercapacitors.However,lim-itations like inferior cycling stability and unsatisfactory charge storage capability at low temperatures have exerted negative effects on their applications.Herein,a novel synthetic process has been elaborately designed and provided to have the composition and structure of the C/N-NiCoMn-LDH/Ag(C/N-CNMA)delicately regulated.Both the experimental and theoretical researches unveil that the incorporated manganese species and elemental silver could dramatically modulate the bandgap,crystallinity and surface electron structure of the LDH,leading to the remarkable improvement in its conductivity,exposed active sites and intrinsic electrochemical activity,and thus the OH^(*)and O^(*)adsorption free energy could be remarkably optimized,even at low temperatures.In addition,the low crystallinity C/N-CNMA is of great electrochemical compatibility with both the KOH aqueous electrolyte and the isobutyl alcohol(IPA)modulated organohydrogel electrolyte.By means of adjusting the solvation and hydrogen bonding in the electrolytes,the assembled hybrid supercapacitors deliver excellent energy density,power density and cycling stability in the temperature range of-30 to 25℃.Specifically,the gel electrolyte with IPA as the anti-freezing functional additive displays high flexibility and ionic conductivity at low temperatures.
基金supported by the National Natural Science Foundation of China(grant no.21975145).Prof.Junqi Sun at Jilin University is thanked for the helpful discussions.
文摘It remains a great challenge to balance the kinetic stability and intrinsic healing ability of polymer materials.Here,we present an efficient strategy of using a synthetic reaction cycle to regulate the intrinsic healing ability of thermodynamically stable and kinetically inert multifunctional organohydrogels.By combining a double decomposition reaction with spontaneous energy dissipation,we can construct the simplest synthetic reaction cycle that can induce a transient out-of-equilibrium state for achieving the healing of organohydrogels with kinetically locked acylhydrazone bonds.In addition to balancing kinetic stability and healing ability,the synthetic reaction cycle also enables the polymer materials to have high tolerance to organic solvents,high ionic strength,high and low temperatures,and other harsh conditions.Therefore,the kinetically stable and healable organohydrogels remain mechanically flexible and electrically conductive even down to−40°C and are readily recyclable.The integration of chemical networks into healable polymers may provide novel,versatile materials for building next-generation electronic devices.
文摘The challenges of enabling zinc air batteries to operate at ultralow temperatures are twofold.The Prerequisite is preventing the electrolyte from freezing while maintaining high ionic conductivity.Secondly,the catalyst has to work efficiently at low temperatures.This highlight presents the latest development to resolve the challenges by tuning the structures of the electrolyte and catalyst,offering a new paradigm to widen the working temperature range of zinc air batteries.
基金This work was supported by the Major Science and Technology Projects of Heilongjiang Province(2019ZX09A01)the National Key Technology R&D Program(2017YFB1401805).
文摘Hydrogel electrolytes with anti-freezing properties are crucial for flexible quasi-solid-state supercapacitors operating at low temperatures.However,the electrolyte freezing and sluggish ion migration caused by the cold temperature inevitably damage the flexibility and electrochemical properties of supercapacitors.Herein,we introduce the concentrated electrolyte into a freezecasted poly(vinyl alcohol)hydrogel film not only reducing the freezing point of the electrolyte(−51.14℃)in gels for ensuring the flexibility,but also improving the ionic conductivity of the hydrogel electrolyte(5.92 mS cm^(−1)at−40℃)at low temperatures.As a proof,an all-in-one supercapacitor,synthesized by the one-step polymerization method,exhibits a good specific capacitance of 278.6 mF cm^(−2)at−40℃(accounting for 93.8%of the capacitance at room temperature),high rate performance(50%retention under the 100-fold increase in current densities),and long cycle life(88.9%retention after 8,000 cycles at−40℃),representing an excellent low-temperature performance.Our results provide a fresh insight into the hydrogel electrolyte design for flexible energy storage devices operating in the wide range of temperature and open up an exciting direction for improving all-in-one supercapacitors.
基金financially supported by the National Natural Science Foundation of China(52063019,51973088,and 51761135114)the“Double Thousand Plan”Science and Technology Innovation High-end Talent Project of Jiangxi Province(jxsq2019201107)+1 种基金the International Science and Technology Cooperation of Jiangxi Province(20203BDH80W011)the Graduate Students Innovation Special Foundation of Jiangxi Province(YC2021-B017)。
文摘Although significant progress has been achieved in developing high energy aqueous zinc ion hybrid supercapacitors(ZHSCs),the sluggish diffusion of zinc ion(Zn^(2+))and unsatisfactory cathodes still hinder their energy density and cycling life span.This work demonstrates the use of nitrogen-doped mesoporous carbon nanospheres(NMCSs)with appropriately hierarchical pore distribution and enhanced zinc ion storage capability for efficient Zn^(2+)storage.The asprepared aqueous ZHSC delivers a significant specific capacity of 157.8 mA h g^(-1),a maximum energy density of 126.2 W h kg^(-1) at 0.2 A g^(-1),and an ultra-high power density of 39.9 kW kg^(-1) with a quick charge time of 5.5 s.Furthermore,the ZHSC demonstrates an ultra-long cycling life span of 50,000 cycles with an exciting capacity retention of 96.2%.More interestingly,a new type of planar ZHSC is fabricated with outstanding low-temperature electrochemical performance,landmark volumetric energy density of 31.6 mW h cm^(-3),and excellent serial and parallel integration.Mechanism investigation verifies that the superior electrochemical capability is due to the synergistic effect of cation and anion adsorption,as well as the reversible chemical adsorption of NMCSs.This work provides not only an innovative strategy to construct and develop novel high-performance ZHSCs,but also a deeper understanding of the electrochemical characteristics of ZHSCs.