Controllable large-scale processing of temperature regulating sheath-core fibers with high-enthalpy for thermal management

Temperature regulating fibers(TRF_(s)) with high enthalpy and high form stability are the key factors for thermal management. However, the enthalpies of most TRFsare not high, and the preparation methods are still at the laboratory scale. It remains a great challenge to use industrial spinning equipment to achieve continuous processing of TRF_(s) with excellent thermal and mechanical properties. Here, polyamide 6(PA6) based TRF_(s) with a sheath-core structure were prepared by bicomponent melt-spinning. The sheath-core TRF(TRF_(sc)) are composed of PA6 as sheath and functional PA6 as core, which are filled with the shape stable phase change materials(ssPCM),dendritic silica@polyethylene glycol(SiO_(2)@PEG). With the aid of the sheath structure, the filling content of SiO_(2)@PEG can reach 30 %, so that the enthalpy of the TRF_(s) can be as high as 21.3 J/g. The ultra-high enthalpy guarantees the temperature regulation ability during the alternating process of cooling and heating. In hot environment, the temperature regulation time is 6.59 min, and the temperature difference is 12.93℃. In addition, the mechanical strength of the prepared TRF_(sc) reaches 2.26 cN/dtex, which can fully meet its application in the field of thermal management textiles and devices to manage the temperature regulation of the human body or precision equipment, etc.

The Effects of Thickness and Location of PCMon the Building’s Passive Temperature-Control–A Numerical Study

Building energy consumption and building carbon emissions both account for more than 20%of their total national values in China.Building employing phase change material(PCM)for passive temperature control shows a promising prospect in meeting the comfort demand and reducing energy consumption simultaneously.However,there is a lack of more detailed research on the interaction between the location and thickness of PCM and indoor natural convection,as well as indoor temperature distribution.In this study,the numerical model of a passive temperature-controlled building integrating the developed PCM module is established with the help of ANSYS.In which,the actual weather condition of Beijing city is set as the boundary conditions and the indoor natural convection is simulated with the consideration of radiation model.The effects of PCM’s thickness and location on the internal temperature field are analyzed and discussed.The results show that the room could maintain within the human comfort temperature range with the longest ratio of 94.10%and the shortest ratio of 51.04%as integrating PCM.In comparison,the value is only 26.70%without PCM.The room’s maximum temperature fluctuation can also be improved;it could be lowered by 64.4%compared to the normal condition.When the quantity of PCM is sufficient,further increasing the PCM amount results in a temperature fluctuation reduction of less than 0.1°C and does not increase the comfort time.Placing PCM on the wall induces an apparent variation in indoor temperature along the vertical direction.Conversely,placing PCM on the roof can lead to a heat transfer rate difference of up to seven times.The optimal placement of PCM depends on the difference between the environmental and phase change temperatures.If the difference is positive,placing PCM on the roof is more effective;conversely,the opposite holds.According to the results over the entire cycle,PCM application on vertical walls yields better performance.The significant difference in natural convection caused by the same thickness of PCM but different application positions,coupled with the influence of air movement on the melting and solidification of PCM,further impacts indoor temperature fluctuations and comfort.This study can provide guidance for the application location and thickness of PCM,especially for scenarios where temperature regulation is required at a specific time.

Temperature Regulation Effect of Desert Vegetation in Minqin Desert Area

[ Objective] The paper was to study the effects of desert vegetation on temperature regulation and stabilization in desert area. [ Method] The survey data of quadrats in five kinds of plant communities in Minqin desert area were preliminarily estimated. [Result] Desert vegetation had the ecological functions of regulating desert temperature and stabilizing sharp increase of temperature, especially the irreplaceable ecological function of slowing down sandstorm each spring in northwest China compared to physical sand-fixatian measures. The air humidity in forest region was relatively large, and the climate was more stable. The climate in desert area was dry, with intense changes in air temperature. Although the solar radiation utilization rate of desert vegetation per unit area in Minqin oasis fringe was 5.8% of that of 100% coverage vegetation, it had non-ignorable significance in regulating temperature of local desert. Regulating temperature was one of the ecological functions of desert vegetation. Previous studies only considered wind proof and sand-fixation functions of desert vegetation, but ignored its temperature regulation effect, and this was the ecological function of vegetation sand control different from physical sand-fixation measures such as sand barrier. [ Conclusion] It has important theoretical guiding significance and practical use value for prevention and control of desertification by studying ecological function of desert plants/vegetation.

Adaptive output-feedback power-level control for modular high temperature gas-cooled reactors

Small modular reactors(SMRs) are beneficial in providing electricity power safely and viable for specific applications such as seawater desalination and heat production. Due to its inherent safety feature, the modular high temperature gas-cooled reactor(MHTGR) is considered as one of the best candidates for SMR-based nuclear power plants. Since its dynamics presents high nonlinearity and parameter uncertainty, it is necessary to develop adaptive power-level control, which is beneficial to safe, stable, and efficient operation of MHTGR and is easy to be implemented. In this paper, based on the physically-based control design approach, an adaptive outputfeedback power-level control is proposed for MHTGRs. This control can guarantee globally bounded closedloop stability and has a simple form. Numerical simulation results show the correctness of the theoretical analysis and satisfactory regulation performance of this control.

Metamaterial terahertz device with temperature regulation function that can achieve perfect absorption and complete reflection conversion of ultrawideband

The field of terahertz devices is important in terahertz technology.However,most of the current devices have limited functionality and poor performance.To improve device performance and achieve multifunctionality,we designed a terahertz device based on a combination of VO_(2)and metamaterials.This device can be tuned using the phase-transition characteristics of VO_(2),which is included in the triple-layer structure of the device,along with SiO_(2)and Au.The terahertz device exhibits various advantageous features,including broadband coverage,high absorption capability,dynamic tunability,simple structural design,polarization insensitivity,and incidentangle insensitivity.The simulation results showed that by controlling the temperature,the terahertz device achieved a thermal modulation range of spectral absorption from 0 to 0.99.At 313 K,the device exhibited complete reflection of terahertz waves.As the temperature increased,the absorption rate also increased.When the temperature reached 353 K,the device absorption rate exceeded 97.7%in the range of 5-8.55 THz.This study used the effective medium theory to elucidate the correlation between conductivity and temperature during the phase transition of VO_(2).Simultaneously,the variation in device performance was further elucidated by analyzing and depicting the intensity distribution of the electric field on the device surface at different temperatures.Furthermore,the impact of various structural parameters on device performance was examined,offering valuable insights and suggestions for selecting suitable parameter values in real-world applications.These characteristics render the device highly promising for applications in stealth technology,energy harvesting,modulation,and other related fields,thus showcasing its significant potential.

Effect of a fever in viral infections-the ‘Goldilocks’ phenomenon?

Acute infections,including those due to Coronaviridae and other viruses,often stimulate a febrile response.A mild fever appears to improve outcome;it appears to diminish viral replication by several mechanisms,including virion entry into host cells and genome transcription,and improving host defence mechanisms against the pathogen.However,a fever may also damage host cellular and tissue function and increase metabolic demands.At temperatures at the lower end of the febrile range,the benefit of the fever appears to outweigh the detrimental effects.However,at higher temperatures,the outcome worsens,suggesting that the disadvantages of fever on the host predominate.A non-infective fever is associated with a worse outcome at lower temperatures,suggesting that hyperthermia carries less benefit in the absence of infection.This review discusses the risks and benefits of a fever on the host response,focusing on the effects of a fever on viral replication and host response,and the detrimental effect on the host.

Cold-humid effect of Baiyangdian wetland

Data support for wetland protection function evaluation can be provided by quantitatively analyzing the ability of regulating the regional climate of the wetland ecosystem. In this study, the cold-humid effect of the Baiyangdian wetland was analyzed by comparing the meteorological conditions of the Baiyangdian wetland and its surrounding areas. Meanwhile, the regulatory functions of the Baiyangdian wetland for the processes and magnitudes of temperature and relative humidity from August to October 2008 were evaluated. The results show that daily mean temperatures in the Baiyangdian wetland were lower than in the surrounding areas, and that temperature differences mainly occurred in the daytime but were not obvious at night. Diurnal temperature ranges in the Baiyangdian wetland were lower than in the surrounding areas, and the higher the diurnal temperature range in the surrounding areas was, the stronger the regulation ability of the Baiyangdian wetland. Compared with the surrounding areas, the decline of the daily minimum temperature in the Baiyangdian wetland was gentler, and the mean relative humidity there was higher. The present findings indicate that effects of the Baiyangdian wetland on climate and humidity regulation are significant.

Temperature-induced lattice distortion in CuGeO_(3) nanocrystals

Lattice distortion represents the fundamental factor of crystalline materials and contributes significantly to structural-related properties.Herein,we discover an unexpected temperature-induced lattice distortion in CuGeO_(3) nanocrystals,resulting in color changes of CuGeO_(3).The structural distortions in CuGeO_(3) nanocrystals are characterized by Rietveld analysis in detail,where its cell parameter b and cell volume reveal first decrease and then increase characteristics and correspond well with the XRD patterns and Raman spectra.Besides,both the experimental characterizations and theoretical calculations confirm that the optical and band structural changes mainly arise from the twisted octahedral field of[CuO_(6)],where the lattice distortions regulate the crystal field splitting energy of[CuO_(6)]and account for its changed d-d transition.Furthermore,tetracycline photodegradation is employed as an example to evaluate the effect of lattice distortion on photocatalytic performance,which also highlights the importance of modulating lattice distortion in photocatalysis.This work provides an approach to simply regulate the lattice distortion for nanorods by manipulating calcination temperatures.

Regulation of the multi-emission centers in carbon dots via a bottom-up synthesis approach

Understanding the luminescence mechanisms and regulating the emission centers of carbon dots(CDs)are important for advancing their related applications.In this work,we systematically investigate the formation processes of multi-emission centers in CDs synthesized through a bottom-up approach by controlling the solvothermal reaction temperature.CDs synthesized at a lower temperature(140℃,140-CDs)exhibit smaller particle sizes(3–4 nm)with dominant green–yellow emission,while CDs synthesized at a higher temperature(180℃,180-CDs)exhibit larger particle sizes(8–9 nm)with enhanced red emission and emerging near-infrared(NIR)emission.The green–yellow emission and red emission originate from the core state and the surface-related state,respectively,and the emissions could be regulated by temperature-controlled dehydration and carbonization processes.The clear NIR emission center in 180-CDs is attributable to the increased content of radical defects in the cores during the increased dehydration and carbonization processes during higher-temperature solvothermal treatment.

Temperature‑Regulating Phase Change Fiber Scaffold Toward Mild Photothermal–Chemotherapy

Photothermal therapy(PTT)is a treatment that increases the temperature of tumors to 42–48℃,or even higher for tumor ablation.PTT has sparked a lot of attention due to its ability to induce apoptosis or increase sensitivity to chemotherapy.Excessive heat not only kills the tumor cells,but also damages the surrounding healthy tissue,reducing therapeutic accuracy and increasing the possible side effects.Herein,a phase change fiber(PCF)scaffold serving as a thermal trigger in mild photothermal–chemo tumor therapy is developed to regulate temperature and control drug release.These prepared PCFs,comprised of hollow carbon fibers(HCFs)loaded with lauric acid as a phase change material(PCM),can effectively store and release any excess heat generated by irradiating with a near-infrared(NIR)laser through the reversible solid–liquid transition process of the PCM.With this feature,the optimal PTT temperature of implanted PCF-based composite scaffolds was identified for tumor therapy with minimal normal tissue damage.In addition,controlled release of chemotherapeutic drugs and heat shock protein(HSP)inhibitors from the PCF-based composite scaffolds have been shown to improve the efficacy of mild PTT.The developed PCF-based scaffold sheds light on the development of a new generation of therapeutic scaffolds for thermal therapy.

Constitutive model for epoxy shape memory polymer with regulable phase transition temperature

The epoxy shape memory polymer(SMP)with adjustable phase transition temperature is a kind of high-performance shape mem-ory polymer,which can change its phase transition temperature and improve its mechanical properties through the process of photo curing.An epoxy SMP constitutive model combining phase transition and viscoelasticity is established by discretizing the epoxy SMP into several glass phase units and rubbery phase units in this paper.The model includes the viscoelastic constitutive equa-tions of glass phase units and rubber phase units,the parameter expression during shape memory process,and material parameter equation during photocuring process.And the stress relaxation behavior of epoxy SMP at different temperatures and the change of material parameters during the photo-curing process are simu-lated numerically,and the simulation results perform consistency with the experimental data.The model can not only relate shape memory effect and phase transformation in physics but also better characterize the viscoelastic properties of SMP and predict the shape memory response of SMP.

Researchers revealed a neural mechanism underlying body temperature regulation

Subject Code:C09 With the support by the National Natural Science Foundation of China,a research group led by Dr.Shen Wei(沈伟)from Shanghai Tech University has deconstructed a neural circuit for body temperature regulation,which was published in PNAS(2017,114:2042—2047).

液态金属基柔性可穿戴热电冷却结构及冷却性能优化

为了提高柔性热电冷却器(TEC)的冷却能力,解决液态金属材料的泄漏问题,同时研究热电腿的尺寸、密度和形状对TEC冷却能力的影响.本文将具有液态核心氧化壳结构的Ni-GaIn(掺镍液态金属)和LMPs(液态金属纳米颗粒)引入柔性TEC中,并针对材料的特性,采用“较大的电极”和“三层PDMS”对传统的热电冷却结构进行了改进.采用“大电极”和“三层PDMS”解决了液态金属量大、易泄漏的问题,降低了成本和环境污染,提高了产品可靠性和制造效率.利用有限元分析软件对结构进行了进一步优化,提供了多物理场和多因素影响下的TEC设计方案.与已报道的采用EGaIn互连和传统热电冷却结构的柔性TEC相比,本文制备的两种新型柔性TEC分别具有冷却能力高(7.4℃)和性能稳定(受弯曲变形影响小)的特点.

Xiyanping injection therapy for children with mild hand foot and mouth disease:a randomized controlled trial

OBJECTIVE: To evaluate the clinical effects of Xiyan-ping injection intervention in pediatric patients with mild hand foot and mouth disease(HFMD).METHODS: A total of 329 patients were stratified and block-randomized for symptomatic treatment of HFMD and assigned to one of the following groups: Western Medicine(group A, n = 103), Xiyanping injection(group B, n = 109), or Xiyanping injection and symptomatic treatment using Western Medicine(group C, n = 117). During the trial, fever,rash, ulcers of the mouth were observed among participants in each group before and after treatment, and conversion rates from mild to severe HFMD were measured.RESULTS: After 3-7 days' treatment, no significant differences in the conversion rates from mild to severe HFMD were observed among the three groups(P > 0.05). There was a significantly low number of patients with the onset time of antifebrile effect,vanished time of hand and foot rashes and cumulative time for the ulcers in the mouth vanished,among the three groups(P < 0.05, P < 0.01). The onset time of antifebrile effect of patients in groups B and C were markedly shorter compared with those in group A(P < 0.05, P < 0.01); there was no statically significant difference observed between groups B and C(P > 0.05). No significant differences were observed in the time for body temperature recovery among the three groups(P > 0.05). There were no significant differences in adverse effects among the three groups(P > 0.05).CONCLUSION: Xiyanping injection together with use of Western Medicine is most effective for symptomatic treatment of mild HFMD. No severe adverse reactions were observed.