Investigation and optimization of high-valent Ta-doped SrFeO_(3-δ)as air electrode for intermediate-temperature solid oxide fuel cells

To explore highly active and thermomechanical stable air electrodes for intermediate-temperature solid oxide fuel cells(ITSOFCs),10mol%Ta5+doped in the B site of strontium ferrite perovskite oxide(SrTa_(0.1)Fe_(0.9)O_(3-δ),STF)is investigated and optimized.The effects of Ta^(5+)doping on structure,transition metal reduction,oxygen nonstoichiometry,thermal expansion,and electrical performance are evaluated systematically.Via 10mol%Ta^(5+)doping,the thermal expansion coefficient(TEC)decreased from 34.1×10^(-6)(SrFeO_(3-δ))to 14.6×10^(-6) K^(-1)(STF),which is near the TEC of electrolyte(13.3×10^(-6) K^(-1) for Sm_(0.2)Ce_(0.8)O_(1.9),SDC),indicates excellent thermomechanical compatibility.At 550-750℃,STF shows superior oxygen vacancy concentrations(0.262 to 0.331),which is critical in the oxygen-reduction reaction(ORR).Oxygen temperature-programmed desorption(O_(2)-TPD)indicated the thermal reduction onset temperature of iron ion is around 420℃,which matched well with the inflection points on the thermos-gravimetric analysis and electrical conductivity curves.At 600℃,the STF electrode shows area-specific resistance(ASR)of 0.152Ω·cm^(2) and peak power density(PPD)of 749 mW·cm^(-2).ORR activity of STF was further improved by introducing 30wt%Sm_(0.2)Ce_(0.8)O_(1.9)(SDC)powder,STF+SDC composite cathode achieving outstanding ASR value of 0.115Ω·cm2 at 600℃,even comparable with benchmark cobalt-containing cathode,Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-δ)(BSCF).Distribution of relaxation time(DRT)analysis revealed that the oxygen surface exchange and bulk diffusion were improved by forming a composite cathode.At 650℃,STF+SDC composite cathode achieving an outstanding PPD of 1117 mW·cm^(-2).The excellent results suggest that STF and STF+SDC are promising air electrodes for IT-SOFCs.

A novel structure of ultra-high-loading small moleculesencapsulated ZIF-8 colloid particles

The safety of nanoparticle-based drug delivery systems(DDSs)for cancer treatment is still a challenge,restricted by the intrinsic cytotoxicity of drug carriers and leakage of loaded drug.Here,we propose a novel nanocarrier’s cytotoxicity avoidance strategy by synthesizing an encapsulation core–shell structure of zeolitic imidazolate framework-8(ZIF-8)-based colloid particles(CPs)with an amorphous ZIF-8 skin.This encapsulation structure achieves an ultra-high loading rate(LR)of 90%(i.e.,9 mg doxorubicin(DOX)per 1 mg ZIF-8)for DOX and the protection of DOX from leaking.Notably,to deliver unit-dose drug,this ultra-high LR of 90%significantly reduces the usage of ZIF-8 to 1.2%(2 orders of magnitude)compared to that of DOX@ZIF-8 with a 10%LR,in which cytotoxicity of ZIF-8 could well below the safety limit and then be relatively ignored.Safety,drug delivery efficacy,scale-up ability,and universality of this encapsulation structure have been further verified.Our findings suggest the great potential of this ZIF-8-based encapsulation core–shell structure in the field of drug delivery.

Diversity analysis of tick-associated viruses in northeast China

Dear Editor,The ongoing threat of tick-borne diseases,especially the increasing rate of new infections caused by tick-borne viruses has drawn wide attention in recent years(Madison-Antenucci et al.,2020;Yang et al.,2023).Therefore,there is a need to strengthen the surveillance of a wide range of viruses carried by ticks to prevent outbreaks of tick-borne diseases.

A harmonic-wave bio-thermal method for continuous monitoring skin thermal conductivity and capillary perfusion rate

The revelation of thermal energy exchange mechanism of human body is challenging yet worthwhile,because it can clearly explain the changes in human symptoms and health status.Understanding,the heat transfer of the skin is significant because the skin is the foremost organ for the energy exchange between the human body and the environment.In order to diagnose the physiological conditions of human skin without causing any damage,it is necessary to use a non-invasive measurement technique by means of a conformal flexible sensor.The harmonic method can minimize the thermal-induced injury to the skin due to its low heat generating properties.A novel type of computational theory assessing skin thermal conductivity,blood perfusion rate of capillaries in the dermis,and superficial subcutaneous tissues was formed by combining the multi-medium thermal diffusion model and the bio-thermal model(Pennes equation).The skins of the hand back of six healthy subjects were measured.It was found that the results revealed no consistent changes in thermal conductivity were observed across genders and ages.The measured blood perfusion rates were within the range of human capillary flow.It was found that female subjects had a higher perfusion rate range(0.0058-0.0061 s^(-1))than male subjects(0.0032-0.0049 s^(-1)),which is consistent with invasive medical studies about the gender difference in blood flow rates and stimulated effects in relaxation situations.

New strategy for boosting cathodic performance of low temperature solid oxide fuel cells via chlorine doping

To enhance the performance and widespread use of solid oxide fuel cells(SOFCs),addressing the low-temperature(<650℃)electrochemical performance and operational stability issues of cathode materials is crucial.Here,we propose an innovative approach to enhance oxygen ion mobility and electrochemical performance of perovskite oxide by substituting some oxygen sites with chlorine anions.The designed SrTa_(0.1)Fe_(0.9)O_(3-δ-x)Clx(x=0.05 and 0.10)exhibits improved performance compared to SrTa_(0.1)Fe_(0.9)O_(3-δ)(STF).SrTa_(0.1)Fe_(0.9)O_(2.95-δ)Cl_(0.05)(STFCl0.05)shows the lowest area-specific resistance(ASR)value on Sm0.2Ce0.8O1.9(SDC)electrolyte.At 600℃,STFCl0.05 achieves an ASR value of 0.084Ω·cm^(2),and a single cell with STFCl0.05 reaches a higher peak power density(PPD)value(1143 mW·cm^(-2))than that with STF(672 mW·cm^(-2)).Additionally,besides exhibiting excellent oxygen reduction reaction(ORR)activity at lower temperatures,the STFCl0.05 cathode demonstrates good CO_(2)tolerance and operational stability.Symmetrical cell operation lasts for 150 h,and single cell operation endures for 720 h without significant performance decline.The chlorine doping approach effectively enhances ORR activity and stability,making STFCl0.05 a promising cathode material for low-temperature SOFCs.

Highly active and durable triple conducting composite air electrode for low-temperature protonic ceramic fuel cells

Protonic ceramic fuel cells(PCFCs)are more suitable for operation at low temperatures due to their smaller activation energy(Ea).Unfortunately,the utilization of PCFC technology at reduced temperatures is limited by the lack of durable and high-activity air electrodes.A lot number of cobalt-based oxides have been developed as air electrodes for PCFCs,due to their high oxygen reduction reaction(ORR)activity.However,cobalt-based oxides usually have more significant thermal expansion coefficients(TECs)and poor thermomechanical compatibility with electrolytes.These characteristics can lead to cell delamination and degradation.Herein,we rationally design a novel cobalt-containing composite cathode material with the nominal composition of Sr_(4)Fe_(4)Co_(2)O_(13)+δ(SFC).SFC is composed of tetragonal perovskite phase(Sr_(8)Fe_(8)O_(23)+δ,I4/mmm,81 wt.%)and spinel phase(Co_(3)O_(4),Fd3m,19 wt.%).The SFC composite cathode displays an ultra-high oxygen ionic conductivity(0.053 S·cm^(-1)at 550℃),superior CO_(2)tolerance,and suitable TEC value(17.01×10^(-6)K^(-1)).SFC has both the O_(2)^(-)/e^(-)conduction function,and the triple conducting(H^(+)/O_(2)^(-)/e^(-))capability was achieved by introducing the protonic conduction phase(BaZr_(0.2)Ce_(0.7)Y_(0.1)O_(3-δ),BZCY)to form SFC+BZCY(70 wt.%:30 wt.%).The SFC+BZCY composite electrode exhibits superior ORR activity at a reduced temperature with extremely low area-specific resistance(ASR,0.677Ω·cm^(2)at 550℃),profound peak power density(PPD,535 mW·cm^(-2)and 1.065 V at 550℃),extraordinarily long-term durability(>500 h for symmetrical cell and 350 h for single cell).Moreover,the composite has an ultra-low TEC value(15.96×10^(-6)K^(-1)).This study proves that SFC+BZCY with triple conducting capacity is an excellent cathode for low-temperature PCFCs.

Rational design of graphyne-based dual-atom site catalysts for CO oxidation

There are increasing concerns about the environmental impact of rising atmospheric carbon monoxide concentrations,thus it is necessary to develop new catalysts for efficient CO oxidation.Based on first-principles calculations,the potential ofγ-graphyne(GY)as substrate for metals in the 4th and 5th periods under single-atom and dual-atoms concentration modes has been systematically investigated.It was found that single-atom Co,Ir,Rh,and Ru could effectively oxidate CO molecules,especially for single Rh.Furthermore,proper atoms concentration could boost the CO oxidation activity by supplying more reaction centers,such as Rh^(2)/GY.It was determined that two Rh atoms in Rh^(2)/GY act different roles in the catalytic reaction:one structural and another functional.Screening tests suggest that substituting the structural Rh atom in the center of acetylenic ring by Co or Cu atom is a possible way to maintain the reaction performance while reducing the noble metal cost.This systemic investigation will help in understanding the fundamental reaction mechanisms on GY-based substrates.We emphasize that properly exposed frontier orbital of functional metal atom is crucial in adsorption configuration as well as entire catalytic performance.This study constructs a workflow and provides valuable information for rational design of CO oxidation catalysts.

Decreasing the CTE of Thermoplastic Polyimide by Blending with a Thermosetting System

A series of thermoplastic polyimide resins with a low coefficient of thermal expansion(CTE)were prepared by blending a rigid resin system 3,3’,4,4’-biphenyltetracarboxylic dianhydride(BPDA)/p-phenylenediamine(PDA)with a flexible resin system 4,4’-[isopropylidenebis(pphenyleneoxy)]diphthalic anhydride(BPADA)/PDA.The effects of the blending ratio on the macromolecular coil size,free volume,and CTE of the mixed system were studied.The mixing is carried out in the prepolymer poly(amide acid)(PAA)stage,which makes the two systems more compatible and is conducive to the formation of a semi-interpenetrating network structure between the rigid molecular chains and flexible molecular chains.The flexible structure of the BPADA/PDA system is used to ensure the melt processing performance.The rigid characteristics of the BPDA/PDA system can inhibit the movement of molecular chains and reduce the free volume fraction,thereby reducing the CTE value.When the rigid system content reaches 30%,the CTE can be reduced to 38 ppm/K.This method provides a new approach for studying low CTE thermoplastic polyimide resins.

Photoaging mechanism of microplastics:a perspective on the effect of dissolved organic matter in natural water

Plastic products widespread in natural water can be broken into smaller-sized microplastics(MPs,<5 mm)under light irradiation,thermal degradation and biodegradation,posing a serious threat to aquatic ecosystems and human health.This perspective concludes that MPs can generate reactive oxygen species(ROS)through initiation,propagation and termination steps,which can attack the polymer resulting in the photoaging and breakdown of C–C and C–H bonds under ultraviolet(UV)irradiation.Free radical generation and weathering degree of MPs depend on their physicochemical properties and environmental conditions.In general,UV irradiation and co-existed MPs can significantly accelerate MP photoaging.With plentiful chromophores carbonyl,carboxyl and benzene rings,Dissolved organic matter(DOM)mainly absorbs photons(300–500 nm)and generates hydrated electrons,^(3)DOM^(*) and ROS,which may affect MP photoaging.However,whether DOM may transfer the electron and energy to MPs under UV irradiation,affect ROS generation of MPs and their photoaging pathway are inadequately studied.More studies are needed to elucidate MP photoaging pathways and mechanisms,consider the influence of stabilization capacity,photosensitization and photoionization of DOM as well as their competitive light absorption with MPs,which provides valuable insights into the environmental behavior and ecological risk of MPs in natural water.

A subpopulation of CD146^(+) macrophages enhances antitumor immunity by activating the NLRP3 inflammasome

As one of the main tumor-infiltrating immune cell types, tumor-associated macrophages (TAMs) determine the efficacy of immunotherapy. However, limited knowledge about their phenotypically and functionally heterogeneous nature restricts their application in tumor immunotherapy. In this study, we identified a subpopulation of CD146+ TAMs that exerted antitumor activity in both human samples and animal models. CD146 expression in TAMs was negatively controlled by STAT3 signaling. Reducing this population of TAMs promoted tumor development by facilitating myeloid-derived suppressor cell recruitment via activation of JNK signaling. Interestingly, CD146 was involved in the NLRP3 inflammasome-mediated activation of macrophages in the tumor microenvironment, partially by inhibiting transmembrane protein 176B (TMEM176B), an immunoregulatory cation channel. Treatment with a TMEM176B inhibitor enhanced the antitumor activity of CD146+ TAMs. These data reveal a crucial antitumor role of CD146+ TAMs and highlight the promising immunotherapeutic approach of inhibiting CD146 and TMEM176B.

Constructing the separation pathway for photo-generated carriers by diatomic sites decorated on MIL-53-NH2(Al)for enhanced photocatalytic performance

High yield production of phenol from hydroxylation of benzene with low energy consumption is of paramount importance,but still challenging.Herein,a new strategy,consisting of using diatomic synergistic modulation(DSM)to effectively control the separation of photo-generated carriers for an enhanced production of phenol is reported.The atomic level dispersion of Fe and Cr respectively decorated on Al based MIL-53-NH_(2)photocatalyst(Fe1/Cr:MIL-53-NH_(2))is designed,in which Cr single atoms are substituted for Al3+while Fe single atoms are coordinated by N.Notably,the Fe1/Cr:MIL-53-NH_(2)significantly boosts the photooxidation of benzene to phenol under visible light irradiation,which is much higher than those of MIL-53-NH_(2),Cr:MIL-53-NH_(2),Fe1/MIL-53-NH_(2),and Fe nanoparticles/Cr:MIL-53-NH_(2)catalysts.Theoretical and experimental results reveal that the Cr single atoms and Fe single atoms can act as electron acceptor and electron donor,respectively,during photocatalytic reaction,exhibiting a synergistic effect on the separation of the photo-generated carriers and thereby causing great enhancement on the benzene oxidation.This strategy provides new insights for rational design of advanced photocatalysts at the atomic level.