Experimental Evaluation of the Blackbody Radiation Shift in the Cesium Atomic Fountain Clock

The cesium atomic fountain clock is the world’s most accurate microwave atomic clock. The uncertainty of blackbody radiation (BBR) shift accounts for an increasingly large percentage of the uncertainty associated with fountain clocks and has become a key factor in the performance of fountain clocks. The uncertainty of BBR shift can be reduced by improving the system environment temperature. This study examined the mechanism by which the BBR shift of the transition frequency between the two hyperfine energy levels of the 133Cs ground state is generated and the calculation method for the BBR shift in the atomic fountain. Methods used to reduce the uncertainty of BBR shift were also examined. A fountain system structure with uniform temperature and good heat preservation was designed, and related technologies, such as that for measuring the temperature of the cesium fountain system, were studied. The results of 20 days of measurements, in combination with computer simulation results, showed that the temperature uncertainty of the atomic action zone is 0.12 °C and that the resulting uncertainty of BBR shift is 2.4 × 10−17.

Diffusion Bonding of Ti6Al4V at Low Temperature via SMAT

Titanium alloys used to be welded to gain good joint strength at 920 °C through diffusion bonding. However, due to the heat preservation at high temperatures for a long time, we obtain joints with great bond strength while the mechanical properties of the sheet are lost. In this paper, taking Ti6Al4V alloy as an example, we studied the microstructure of the surface under the different times of surface mechanical attrition treatment (SMAT). In addition, the microstructure and mechanical properties after diffusion bonding at 800 °C-5 MPa-1 h were also conducted. The results show that the shear strength of TC4 alloy welded joint after SMAT treatment is improved, and the maximum shear strength can reach 797.7 MPa, up about 32.4%

Research on the Application Value of Intelligent Heating Box in Newborn Nursing

The aim of this study was to explore the application effect of intelligent incubator in neonatal care. We selected the period from January 1, 2018, to December 31, 2020, where there were 100 full-term and premature babies born in a hospital and transferred to the neonatal intensive care unit (NICU) within 1 hour after birth. Before the improved heat preservation, 100 full-term infants in the control group and 100 full-term infants in the intervention group of the intelligent warming box were formed into a full-term infant group for a comparative study. Statistics and comparison of the two groups of term infants and premature infants admitted to the hospital were carried out to assess body temperature and the changes in the incidence of each system. The research found that on comparison of admission body temperature between the control group and the intervention group, with the intervention group in the intelligent heating box, the incidence of hypothermia was significantly lower than that of the control group (95% vs. 37% of full-term infants; 98% vs. 49% of premature babies; there is a statistical significance ( P < 0.05 )). The intelligent heating box can reduce the fluctuation of the newborn’s body temperature, keep the internal environment of newborns stable, and provide suitable conditions for the rapid growth of newborns, suitable for clinical promotion and application.

Effect of external thermal insulation layer on the Chinese solar greenhouse microclimate

In order to optimize the heat preservation capacity of Chinese solar greenhouse (CSG) and further reduce energy consumption, we clarified the mechanism of the external thermal insulation layer that affects the microclimate environment of CSG. The most suitable external insulation layer thickness (EILT) of the solar greenhouse envelope structure in high latitude and cold region has been indicated. A three-dimensional mathematical model was developed based on computational fluid dynamics and verified using experimental measurement. The temperature variations, heat variations and economic benefit were analysed. The results indicated that covering the outer surface of the enclosures with a thermal insulation layer could effectively increase the greenhouse temperature by 1.2–4.0°C. The influence degree of the external thermal insulation layer on the greenhouse microclimate was as follows: sidewall (SW) > north wall (NW) > north roof (NR). In high-dimensional and cold areas, covering the outer surface of all enclosures with insulation layer as the suitable solution could raise the greenhouse air temperature maximally. The suitable EILT of each maintenance structure was obtained as follows: NW 80 mm, SW 80 mm, NR 100 mm.

Research on Optimization of Cross-sectional shape for Aircraft Door Rubber Seal

Rubber seals are widely used in aircraft door structures, which play important roles on sealing, sound insulation and heat preservation. Aircraft door rubber seals are critical to the normal flight of the aircraft and the safety of the passengers. In this paper, a finite element model of rubber seals for aircraft door with different cross-sections is established. The deformation and stress distribution of the seals under the action of concentrated force and compressive displacement are analyzed, and the calculation results of seals with different cross-sections are compared. The optimal structural form of the cross-sectional shape of the seal is obtained. The research results are of great significance to improve the safety and durability of seals and enhance the sealing performance.

Green Constructing an Intelligent Temperature-Regulating Fabric with Multiple Heat-Transfer Capabilities

Textiles with heat management function have good effects on improving human comfort during sport. However, it is still a great challenge to endow textiles with responsiveness to external environmental changes. Herein, we developed an intelligent temperature-regulating cotton textile with multiple heat transfer capability by a two-step method. Firstly, hydroxylated boron nitride (BN-OH) nanosheet dispersion liquid was prepared using a two-step ultrasonic-alkali treatment. Subsequently, enzymatic graft polymerization of N-isopropyl acrylamide (NIPAM) onto cotton fibers were performed using horseradish peroxidase (HRP). The composite cotton fabric, containing entrapped BN-OH exhibits unique temperature-regulating ability, and the thermal diffusivities in vertical and parallel directions reach 1.2 and 1.7 times of the untreated, respectively. This can be attributed to the temperature responsiveness of poly-NIPAM (PNIPAM) and the increase in the packing density of the thermal conductive nanosheets at high temperatures. Meanwhile, the PNIPAM covering the fiber surfaces slowly expands at low temperatures, accordingly minishes the gap sizes between fabric yarns and endows the fabric with improved heat preservation effects. The present work provides a facile and green strategy for developing the intelligent textiles with ambient temperature self-response ability.

Dandy-Walker malformation in methylmalonic acidemia: a rare case report

Background Methylmalonic acidemia is an organic acid metabolism disorder that usually has nonspecific clinical manifestations. Case presentation A 3-month-old female infant was admitted to the hospital for developmental retardation. Her prenatal and birth history was unremarkable. After admission, she developed dyspnea and severe anemia and was subsequently transferred to the intensive care unit. Magnetic resonance imaging of her brain showed a Dandy-Walker malformation, and metabolic screening indicated methylmalonic acidemia. Thus, she was diagnosed with methylmalonic acidemia and Dandy-Walker malformation. The patient underwent treatment including acidosis correction, blood transfusion, antibiotics, mechanical ventilation and heat preservation. Unfortunately, her condition progressively worsened and she died of metabolic crisis. Conclusions Dandy-Walker malformation may be a clinical manifestation of methylmalonic acidemia. Additionally, the co-existence of methylmalonic acidemia and Dandy-Walker malformation may be an uncharacterized syndrome which needs to be studied further.

Numerical Simulation of Hi Thermal Decomposer in Iodine-Sulfur Cycle Process

The very high-temperature gas-cooled reactor is a fourth-generation reactor with inherent safety and modular high-temperature characteristics. Utilizing ultra-high temperature heat to produce hydrogen by iodine-sulfur cycle is one of the important applications. In this process, the decomposition of hydroiodic acid determines the efficiency of hydrogen production, so it is important to design a hydroiodic acid decomposer with the compact structure and good heat preservation. In this paper, numerical simulations are performed on the hydroiodic acid decomposer used for the decomposition of hydroiodic acid. The species transport model, volume reaction and porous model are used to calculate the temperature field and the distribution of each component. The results show that the temperature of the catalytic zone meets the reaction requirements, the temperature drop in the reactor is about 55 K, and the overall decomposition fraction can reach 21.4%. The current flow rate has an acceptable performance for the improvement of the decomposition rate. The results of this study can provide theoretical calculation references for the engineering application of hydroiodic acid decomposers.