Ultra-low Temperature Research Articles

Hydrogen bond crosslinking hydrogel for high-performance ultra-low temperature MXene-based solid state supercapacitors

The electrochemical performance of aqueous electrolytes at low temperatures is frequently suboptimal due to their low freezing point (0 °C). In this study, we constructed MXene-based ultra-low temperature polyvinyl alcohol/nanocellulose-H2SO4 (PVA/CNF-H2SO4) hydrogel electrolytes utilising hydrogen bonding between water molecules and nanocellulose. The process results in a reduction in the amount of free water present in the hydrogel electrolyte, lowering its freezing point to -77.35 °C. PVA/CNF-H2SO4-based solid-state supercapacitors (C7-SSC) demonstrate a capacitance of up to 813 mF cm-2 at -50 °C, exhibiting high-rate performance at low temperatures. The capacitance remains at 45 F g-¹ at a current density of 20 A g-¹. The maximum areal energy and power densities of our C7-SSC achieve 113 μWh cm-² and 0.4 μW cm-² at -50 °C, respectively, surpassing the majority of state-of-the-art devices. This work provides new insights into MXene-based hydrogel manufacturing and expands the range of potential applications for such materials.

Carbon Nanofibers Encapsulated CoNiFe Bifunctional Electrocatalysts for Durable Zn-Air Batteries at Room and −40 °C Ultralow Temperatures

Carbon Nanofibers Encapsulated CoNiFe Bifunctional Electrocatalysts for Durable Zn-Air Batteries at Room and −40 °C Ultralow Temperatures

Experimental optimization and evaluation of an R600a/R1150 auto-cascade refrigeration systems for ultra-low temperature applications

Auto-cascade refrigeration systems are the most employed systems for ultra-low temperature applications, especially for small capacity systems. Recent investigations have allowed to analyze them energetically and thermodynamically, starting a research line focused on enhancing their energy performance from experimental approaches. This work focuses on the energy optimization of a real auto-cascade system working with the mixture R600a/R1150 [70/30 %], which has been evaluated using two compressor models for R404A and R290 as well as the optimization of the two capillary tubes used in the system. Results indicate that overall efficiency of the R290 compressor is up to 21 % higher than with R404A, leading to COP increments between 35 and 81 %. Optimum capillary lengths have been determined in terms of COP and energy consumption, reaching similar values, however, the inner parameters of the system change as function of these lengths, which needs to be considered in prototypes design.

Harsh Environment-Tolerant, High Performance Soft Pressure Sensors Enabled by Fiber-Segment Structure and Plasma Treatment.

As the demand for specialized and diversified pressure sensors continues to increase, excellent performance and multi-applicability have become necessary for pressure sensors. Currently, flexible pressure sensors are primarily utilized in fields such as health monitoring and human-computer interaction. However, numerous complex extreme environments in reality, including deep sea, corrosive conditions, extreme cold, and high temperatures, urgently require the services of flexible devices. Here, a piezoresistive flexible pressure sensor based on expanded polytetrafluoroethylene/functionalized carbon nanotubes (EPTFE/FCNT) is proposed. Benefiting from the unique fiber-segment architecture, chemical stability, and strong chemical binding force between EPTFE and FCNT, the fabricated sensor exhibits remarkable sensing capabilities and can be employed in multifarious extreme environments. It demonstrates a sensitivity of 862.28kPa-1, a response time of 6-7ms, and a detection limit below 1Pa. Furthermore, it possesses a pressure resolution of 0.0018% under 111kPa and can withstand over 10,000 loading and unloading cycles under 1MPa. Additionally, the EPTFE/FCNT sensor retains its outstanding pressure response and work efficiency in extreme conditions such as an ultra-low temperature of -80°C, high temperature (200°C), acidic and alkaline corrosion, and underwater. These notable attributes enormously broaden the sensors' real-world application range.

The use of orthogonal analytical approaches to profile lipid nanoparticle physicochemical attributes

Abstract Lipid nanoparticles have become a major disruptor within the drug delivery field of complex RNA molecules. The wide applicability of prototype nanomedicines have the potential to fill clinical requirements against current untreatable diseases. The uptake and implementation of analytical technologies to evaluate these prototype nanomedicines have not experienced similar growth rates hindering the translation of LNPs. Here, we evaluate a model RNA-LNP formulation with a selection of routine, and high-resolution orthogonal analytical techniques across studies on manufacturing process parameter impact and formulation stability evaluation under refrigerated and ultra-low temperatures. We analysed model cationic RNA complexed lipid nanoparticle formulation through process impact on formulation critical quality attributes, short term refrigerated stability evaluation, and frozen storage stability using zetasizer dynamic light scattering and nanoparticle tracking analysis. We also evaluated freeze/thaw induced stress on LNP formulation using high resolution field-flow fractionation. Statistical analysis and correlations between techniques were drawn to further enhance our understanding of LNP formulation design, and physiochemical attributes to facilitate LNP formulation clinical translation.

Montmorillonite modified by composite modifier as a rheological regulator of drilling fluid suitable for ultra-low temperature conditions in Antarctica

Montmorillonite modified by composite modifier as a rheological regulator of drilling fluid suitable for ultra-low temperature conditions in Antarctica

High Molecular Weight Semicrystalline Substituted Polycyclohexene From Alternating Copolymerization of Butadiene and Methacrylate and Its Ambient Depolymerization.

Cyclohexene cannot be polymerized via ring-opening polymerization under any conditions due to its lack of ring strain. A hypothetical polycyclohexene would therefore have a strong thermodynamic driving force to depolymerize to monomer if a metathesis catalyst were provided while otherwise having thermal and hydrolytic stability under normal conditions because of its hydrocarbon backbone. We envisioned access to this otherwise unattainable family of polymers via the alternating polymerization of a diene and an alkene. Ethyl aluminum chloride was found to promote highly alternating polymerization of butadiene and methacrylate when radically initiated at room temperature, resulting in formal polycyclohexene structures. Ultrahigh molecular weight (up to 1750 kDa) polymers can be synthesized at the decagram scale in high monomer conversions. The resulting presumably atactic copolymers exhibited semicrystallinity, leading to high toughness. In the presence of a small amount of the Grubbs catalyst, the generated polycyclohexene can be fully depolymerized at ambient temperatures into pure constituent cyclohexene. The strategy of using orthogonal chemistry for the polymerization and depolymerization processes allows access to polymer structures with subambient ceiling temperatures without using ultralow temperature synthesis or relying on the monomer-polymer equilibrium.

Ultra-low temperature selective catalytic reduction of NOx into N2 by micron spherical CeMnOx in high-humidity atmospheres containing SO2

The solvothermal synthesis of optimized micron-sized spherical Ce1Mn7Ox-350 yields remarkable results in ultra-low temperature NH3-SCR of NOx, with over 91 % NOx conversion achieved between 59 and 255 ℃. Notably, under 5 vol% H2O and 50 ppm SO2, the Ce1Mn7Ox maintains NOx conversion >99 % at 127 ℃ for extended periods, surpassing current ultra-low temperature deNOx standards. This superior performance is attributed to the material's unique characteristics: the regular and porous surface morphology enhances exposure to active sites, particularly Mn3O4(112) facets crucial for ultra-low temperature deNOx, while the rough and loose surface and high Mn2O3(222) exposure mitigate water vapor and SO2 poisoning. Furthermore, the thermal storage effect of the Mn2O3/Mn3O4 system within Ce1Mn7Ox facilitates rapid thermal dissipation and ammonium sulfite decomposition. This process is further augmented by the pores, which aid in the confinement of deNOx reaction heat and facilitate the flushing of flowing flue gas, thereby impeding the formation of ammonium bisulfate.

Theoretical analysis of the initial nucleation characteristics of trace water vapor frosting on a cryogenic surface

In certain extreme conditions characterized by ultra-low water vapor content and ultra-low temperatures (e.g. cryogenic wind tunnel), trace water vapor frosting can also pose significant hazards. Considering the crucial role of initial nucleation on subsequent frosting processes, this study firstly investigated and compared the nucleation characteristics of frosting at different water vapor contents (0.1−1000 ppmv) from humid air to trace water vapor based on classical nucleation theory. The preferred nucleation phase diagrams and critical nucleation conditions were analyzed. Sensitivity of the nucleation mass transfer rate, as well as the frosting pathways were further identified. Results show that the nucleation characteristics of trace water vapor frosting (<100 ppmv) is significantly different from that of humid air frosting (>1000 ppmv). Trace water vapor frosting is more inclined towards desublimation nucleation due to its lower nucleation temperature and larger critical contact angle. The critical contact angles for 1000 ppmv, 100 ppmv and 0.1 ppmv are 49°, 75° and 120°, respectively. Furthermore, trace water vapor nucleation requires a greater subcooling degree, has a smaller critical nucleation radius, and is highly sensitive to surface contact angle and further-subcooling degree. At a surface contact angle of 120°, the nucleation subcooling degree of 0.1 ppmv is 2.9 K greater than that of 1000 ppmv. This study helps understanding the nucleation characteristics under different water vapor content conditions, which indicates that reducing subcooling degree and increasing contact angle are more effective anti-frosting methods than reducing water vapor content for trace water vapor frosting.

Analysis of the morphology of Sus scrofa domesticus oocyte-cumulus complexes exposed to low and ultra-low temperatures

Relevance. The priority task of reproductive technologies in animal husbandry is the development of effective storage protocols for female gametes. One way to preserve gametes is vitrification, which reduces damage to intracellular organelles by increasing viscosity upon cooling and minimizing crystallization.Methods. Various additives to cryoprotectants are used for optimization. In our work, titanium tetrapolyethylene glycolate was used in a 10-fold molar excess of polyethylene glycol (TTPEG*10PEG), the nature of the effect of which on cells was studied during short-term storage at low (5 °С) and ultra-low temperatures (-196 °С).The purpose of the study is a comprehensive analysis of the morphology of gametes and somatic cells (cumulus) of ovarian follicles of pigs after exposure to low and ultra-low temperatures (vitrification) when included in the TTPEG*10PEG low-temperature storage and vitrification protocol.Results. Exposure to TTPEG*10PEG at 5 °С caused an increase in the level of oocytes with subsequent morphological degenerations in points with control (from 13% to 5%, р = 0.005). After vitrification with TTPEG*10PEG: the level of gametes with low cumulus cells expansion increased to 35% in terms of the proportion of control gametes (23%); the proportion of denudated gametes was reduced to 50% compared to the control 65% (р &lt; 0.05); the level of morphologically degenerated gametes corresponded to that of native oocytes (8% each) and was lower than in the control (17%), р &lt; 0.005. The obtained data indicate the protective and cryoprotective effects of TTPEG*10PEG at a concentration of 2%, which suggests the possibility of its use in the technology of intraovarian vitrification of female reproductive cells.

Silicon carbide ultrafiltration ceramic membrane sintered by ultra-low temperature oxidation

Silicon carbide (SiC) ceramic membranes are promising components for the efficient treatment of various wastewaters in membrane-based techniques. However, the high preparation temperature and then the high production cost inhibits their large-scale application. Here, an ultra-low temperature sintering process was proposed to prepare SiC ultrafiltration membrane. When the ceramic membrane was heated at 600 °C in air, a selective layer comprised of α-SiC and β-SiC formed without the emergence of crystalline silica. The thickness of the membrane layers was determined by the solid content and viscosity of the slurry. Well-dispersed SiC grains and homogeneous-distributed pores formed in the selective layers when using 100 nm SiC powders. The water flux and emulsion flux were investigated to verify the permeability of the ceramic membrane. Thus, this work proposes an energy-saving process for the preparation of SiC UF membrane and achieves the preparation of SiC UF membrane at ultra-low temperature.

Reduce energy consumption in your laboratory – switch ultra-low temperature freezers from – 80 °C to –70 °C. A pilot study on short term storage of plasma samples for coagulation testing

It is common practice in laboratories to store biological samples in ultra-low temperature (ULT) freezers. There is growing interest in raising the temperature of ULT freezers in order to save energy and reduce expenses, as energy conservation becomes increasingly important and sustainable laboratory practices gain popularity. In our laboratory, plasma samples are stored for three months for diagnostic purposes. We therefore took the opportunity to investigate the effect of two different storage temperatures (−70 °C vs −80 °C), on activated partial thromboplastin time (APTT), factor VIII (FVIII), international normalized ratio (INR) and factor VII (FVII) measurements on paired plasma samples collected from 26 individuals after three months of storage. Automated coagulation analysers CS-5100 and ACL TOP were used to perform the tests. We found no consistent difference between the two storage temperatures for any of the four coagulation parameters (all p-values > 0.05). We conclude that the temperature of ULT freezers used to store plasma samples for APTT, FVIII, INR, and FVII measurements can be safely increased from −80 to −70 °C without affecting the stability of the samples.

Longevous ionogels with high strength, conductivity, adhesion and thermoplasticity

The longevity of flexible electronics substantially influences their viability for practical use. At present, the service life of pliable devices utilizing conductive gels is frequently compromised due to factors inclusive but not limited to solvent loss. Taking cues from the steadfast structure of human tissues, we hereby delineate a solvent-assisted strategy to fabricate ionogels, predicated on a supramolecular network of hydrogen bonds. Upon subjecting these ionogels to realistic operational environments, it has been empirically ascertained that they maintain a steadfast mechanical and electrical consistency for a minimum duration of 22 months. In terms of dynamic stretchability, they effortlessly endure one million stretch cycles, even when faced with a notch. The induction of a supramolecular structure within the ionogel not only confers exceptional mechanical attributes but also simultaneously enhances conductivity, a feat paralleled by few recent explorations. Furthermore, these ionogels boast of superior anti-freezing and adhesive characteristics, including a toughness extending up to 17.96 MJ/m3 at an ultra-low temperature of −50 °C, and an adhesive capacity permitting movement and bearing of items weighing over 10,000 times its own weight, the lap-shear strength can reach 30.2 kPa. Intriguingly, these gels demonstrate thermoplastic behavior, which facilitates their easy reshaping into diverse forms. Such compelling attributes amplify the potential of supramolecular ionogels, positioning them as formidable contenders for flexible electronics in stringent and challenging scenarios.

The impact of climate on relief in the northern Japanese Alps within the past 1 Myr–The case of the Tateyama mountains

The impact of climate on mountain relief is often questioned, mainly due to the difficulties of measuring surface processes at the timescale of glacial-interglacial cycles. An appropriate setting for studying mountain erosion in response to Quaternary climate change is found in the Tateyama mountains in the Hida mountain range (northern Japanese Alps) due to distinct geomorphological features. The Japanese Alps uplifted within the past ∼1–3 Myr and experienced multiple glaciations during the late Quaternary. We use ultra-low temperature thermochronometers based on the luminescence of feldspar minerals from 19 rock samples and the electron spin resonance (ESR) of quartz minerals from 8 rock samples, in combination with inverse modelling to derive rock cooling rates and exhumation rate histories at 104–106 year timescales from three transects in the Tateyama region. While luminescence signals have already reached their upper dating limit, ESR signals (Al and Ti centres) yielded ESR ages of ∼0.3–1.1 Ma, implying surface processes active in the Pleistocene. Based on a negative age-elevation relationship, local relief reduction at a cirque-basin scale is identified over the past 1 Myr, whereas a positive age distribution with elevation for samples close to the mountain top does not follow this trend. Inverse modelling reveals rock cooling rates on the order of 20–70 °C/Myr, with slightly faster cooling for cirque-floor samples, which equate with erosion rates of 0.5–1 mm/yr that exceed rates from periglacial and slope processes in the same locality. Thus, our data suggest that Quaternary climate change coupled with distinct surface processes modified the slopes of the Tateyama mountains leading to a localised decrease in relief within an individual cirque basin over the second half of the Quaternary.

Proton‐Driven Dynamic Behavior of Nanoconfined Water in Hydrophilic MXene Sheets

Liquid water under nanoscale confinement has attracted intensive attention due to its pivotal role in understanding various phenomena across many scientific fields. MXenes serve an ideal paradigm for investigating the dynamic behaviors of nanoconfined water in a hydrophilic environment. Combining deep neural networks and an active learning scheme, here we elucidate the proton‐driven dynamics of water molecules confined between V2CTx sheets using molecular dynamics simulation. Firstly, we have found that the Eigen and Zundel cations can inhibit water‐induced oxidation by adjusting the orientation of water molecules, thus proposing a general antioxidant strategy. Besides, we also identified a hexagonal ice phase with abnormal bonding rules at room temperature, rather than only at ultralow temperatures as other studies reported, and further captured the proton‐induced water phase transition. This highlighted the importance of protons in the maintaining stable crystal phase and phase transition of water. Furthermore, we discussed the conversions of different water structures and water diffusivity with changing proton concentrations in detail. The results provide useful guidance in practical applications of MXenes including developing antioxidant strategies, identifying novel 2D water phases and optimizing energy storage and conversion.

Intracytoplasmic sperm injection zone: insights and applications from a university-based assisted reproduction laboratory

Intracytoplasmic sperm injection (ICSI) has become one of the most important tools used for in vitro production of embryos (IVP) in equine reproduction management programs around the world. This procedure is often performed in the US for several breeds and is used primarily to optimize foal production for broodmares and performance mares but also for stallions with limited semen availability or poor semen quality. As such, there are a limited number of US laboratories capable of using this method, which requires advanced training of personnel and specialized equipment. Many veterinarians and breeding farms currently aspirate ovarian follicles in cycling mares and ship oocytes to ICSI-capable laboratories, where embryos can be produced and typically vitrified for ultralow temperature storage and transport for transfer to recipient mares and establishment of surrogate pregnancies. The Veterinary Assisted Reproduction Laboratory in the School of Veterinary Medicine at the University of California, Davis, maintains a 3-dimensional approach to equine assisted reproductive technology. We offer commercial solutions to breeders, educational advice and training to other laboratories, veterinarians, and visiting scholars. Moreover, as a research laboratory, our objective is to analyze and apply observations from IVP to elucidation of complex developmental problems such as embryonic and fetal loss. In 2018, we reported the birth of the first foal produced at UC Davis using ICSI, and we have since developed a commercial ICSI program for practitioners and horse breeders in the US. Today, our laboratory receives thousands of immature oocytes for ICSI sessions every year, with an average of 2 embryos per mare-session. Our research is focused on molecular, cellular and genetic aspects of gamete biology, perifertilization events, and early equine development using an array of tools including advanced microscopy, sequencing, and time-lapse imaging of developing embryos. In this review, we have highlighted our laboratory’s current methods for commercial equine IVP and research and clinical studies conducted to optimize IVP in horses.

Challenges and Perspectives of Environmental Catalysis for NO x Reduction.

Environmental catalysis has attracted great interest in air and water purification. Selective catalytic reduction with ammonia (NH3-SCR) as a representative technology of environmental catalysis is of significance to the elimination of nitrogen oxides (NO x ) emitting from stationary and mobile sources. However, the evolving energy landscape in the nonelectric sector and the changing nature of fuel in motor vehicles present new challenges for NO x catalytic purification over the traditional NH3-SCR catalysts. These challenges primarily revolve around the application limitations of conventional industrial NH3-SCR catalysts, such as V2O5-WO3(MoO3)/TiO2 and chabazite (CHA) structured zeolites, in meeting both the severe requirements of high activity at ultralow temperatures and robust resistance to the wide array of poisons (SO2, HCl, phosphorus, alkali metals, and heavy metals, etc.) existing in more complex operating conditions of new application scenarios. Additionally, volatile organic compounds (VOCs) coexisting with NO x in exhaust gas has emerged as a critical factor further impeding the highly efficient reduction of NO x . Therefore, confronting the challenges inherent in current NH3-SCR technology and drawing from the established NH3-SCR reaction mechanisms, we discern that the strategic manipulation of the properties of surface acidity and redox over NH3-SCR catalysts constitutes an important pathway for increasing the catalytic efficiency at low temperatures. Concurrently, the establishment of protective sites and confined structures combined with the strategies for triggering antagonistic effects emerge as imperative items for strengthening the antipoisoning potentials of NH3-SCR catalysts. Finally, we contemplate the essential status of selective synergistic catalytic elimination technology for abating NO x and VOCs. By virtue of these discussions, we aim to offer a series of innovative guiding perspectives for the further advancement of environmental catalysis technology for the highly efficient NO x catalytic purification from nonelectric industries and motor vehicles.

Unlocking Fast Potassium Ion Kinetics: High-Rate and Long-Life Potassium Dual-Ion Battery for Operation at -60 °C.

Energy storage devices operating at low temperatures are plagued by sluggish kinetics, reduced capacity, and notorious dendritic growth. Herein, novel potassium dual-ion batteries (PDIBs) capable of superior performance at -60 °C, and fabricated by combining MXenes and polytriphenylamine (PTPAn) as the anode and cathode, respectively, are presented. Additionally, the reason for the anomalous kinetics of K+ (faster at low temperature than at room temperature) on the Ti3C2 anode is investigated. Theoretical calculations, crossover experiments, and in situ XRD at room and low temperatures revealed that K+ tends to bind with solvent molecules rather than anions at subzero temperatures, which not only inhibits the participation of PF6 - in the formation of the solid electrolyte interphase (SEI), but also guarantees co-intercalation behavior and suppresses undesirable K+ storage. The advantageous properties at low temperatures endow the Ti3C2 anode with fast K+ kinetics to unlock the outstanding performance of PDIB at ultralow temperatures. The PDIBs exhibit superior rate capability and high capacity retention at -40 °C and -60 °C. Impressively, after charging-discharging for 20,000 cycles at -60 °C, the PDIB retained 86.7 % of its initial capacity. This study reveals the influence of temperatures on MXenes and offers a unique design for dual-ion batteries operating at ultralow temperatures.

Unlocking Fast Potassium Ion Kinetics: High‐Rate and Long‐Life Potassium Dual‐Ion Battery for Operation at −60 °C

AbstractEnergy storage devices operating at low temperatures are plagued by sluggish kinetics, reduced capacity, and notorious dendritic growth. Herein, novel potassium dual‐ion batteries (PDIBs) capable of superior performance at −60 °C, and fabricated by combining MXenes and polytriphenylamine (PTPAn) as the anode and cathode, respectively, are presented. Additionally, the reason for the anomalous kinetics of K+ (faster at low temperature than at room temperature) on the Ti3C2 anode is investigated. Theoretical calculations, crossover experiments, and in situ XRD at room and low temperatures revealed that K+ tends to bind with solvent molecules rather than anions at subzero temperatures, which not only inhibits the participation of PF6− in the formation of the solid electrolyte interphase (SEI), but also guarantees co‐intercalation behavior and suppresses undesirable K+ storage. The advantageous properties at low temperatures endow the Ti3C2 anode with fast K+ kinetics to unlock the outstanding performance of PDIB at ultralow temperatures. The PDIBs exhibit superior rate capability and high capacity retention at −40 °C and −60 °C. Impressively, after charging‐discharging for 20,000 cycles at −60 °C, the PDIB retained 86.7 % of its initial capacity. This study reveals the influence of temperatures on MXenes and offers a unique design for dual‐ion batteries operating at ultralow temperatures.

Entropy-Driven Hydrated Eutectic Electrolytes with Diverse Solvation Configurations for All-Temperature Zn-ion Batteries.

Batteries always encounter uncontrollable failure or performance decay under extreme temperature environments, which is largely limited by the properties of electrolytes. Herein, an entropy-driven hydrated eutectic electrolyte (HEE) with diverse solvation configurations is proposed to expand the operating temperature range of Zn-ion batteries. The HEE possesses over 40 types of Zn2+ solvation structure with uniform distribution, contributing to its much higher solvation configurational entropy compared to the conventional aqueous counterpart (only 6 types). These effectively promote its anti-freezing ability under ultralow temperatures, with a high ionic conductivity of 0.42 mS cm-1 even at a low temperature of -40 °C. Moreover, the entropy-driven property can simultaneously enhance the thermal stability under a high temperature over +140 °C. Therefore, the HEE can enable full cells stably working over a wide temperature range of -40~+80 °C, performing over 1500 cycles with 100 % capacity retention at -40 °C and 1000 cycles with ~72 % capacity retention at +80 °C. This inspiring concept of entropy-driven electrolyte with quantized solvation configurational entropy value has charming potential for designing future special batteries with excellent adaptability towards extreme temperature environments.