早产儿能量摄入与胰岛素样生长因子-1的关系

目的:探讨早产儿能量摄入与血清中胰岛素样生长因子-1(insulin like growth factor 1,IGF-1)的浓度关系.方法:早产儿57例,分为＜30周、～＜34周、～＜37周3组,计算每日静脉及肠道摄入总热卡,将能量摄入分为30～50 kcal·kg-1·d-1,50～100 kcal·kg-1·d-...     

NSF-Based Analysis of the Structural Stressing State of Trussed Steel and a Concrete Box Girder

This paper analyses the characteristics of the mechanical behavior of a trussed steel and concrete box beam under bending conditions based on the structural stressing state theory and the numerical shape function method. Firstly, the parametric generalized strain energy density was introduced to characterize the structural stressing state of trussed steel stud concrete box girders, and the strain energy density sum was plotted. Then the Mann-Kendall criterion was used to discriminate the leap point of the curve change and to redefine the structural failure load. By analyzing the strain and displacement, the existence of a sudden change in the structural response during the load-bearing process was again demonstrated. Afterwards, the numerical shape function method was used to extend the strain data, and further in-depth analyses of strain/stress fields and internal forces were carried out to show in detail the working characteristics of each under load. Through an in-depth analysis from different angles, the rationality of updating the failure load was verified. Finally, the effects of different structure parameters on the evolution of the structural stresses of the members were analyzed in a transversal comparison. The analysis results of the stress state of a steel-concrete truss structure reveal the working behavior characteristics of a steel-concrete truss structure from a new angle, which provides a reference for the design of a steel-concrete truss structure in the future.     

The Matrix Matters: Beverage Carbonation Impacts the Timing of Caffeine Effects on Sustained Attention

Both caffeine and the perception of refreshment delivered by cooling, tingling, and mouth-watering flavors have individually been shown to positively impact cognitive performance and mood, though presently there is limited evidence on their possible combined effects. This study explored the contribution of refreshing compounds in beverages, namely, carbon dioxide and citric acid, on the acute effects of caffeine on sustained attention and self-rated physical and mental energy. A randomized, controlled crossover trial was conducted by testing three products: a carbonated caffeinated beverage; a comparator caffeinated beverage; and a flavor-matched control beverage. Findings from 24 healthy adults revealed product-dependent variations in cognitive performance during a 60-min visual sustained-attention task, suggesting that the carbonated-caffeinated beverage led to faster, greater and more consistent levels of accuracy, compared to the control beverage. Specifically, significant differences were found between: (1) the carbonated-caffeinated beverage and the caffeinated beverage, and (2) between the caffeinated beverage and the control beverage for number of hits, reaction time and false alarm scores. Both caffeinated beverages led to higher physical and mental energy, and lower physical and mental fatigue 60-min post-consumption. These findings suggest beneficial effects on sustained attention through the combination of caffeine with refreshing compounds.     

Dietary Intake over a 7-Day Training and Game Period in Female Varsity Rugby Union Players

This study estimated the daily energy intake (EI) and energy expenditure (TDEE) in female varsity rugby union players during a weekly training/game cycle. Fifteen (nine forwards, six backs) players (20.5 ± 0.4 y, 167.1 ± 1.8 cm, 74.9 ± 2.9 kg) were monitored for a 7-day period (one fitness, two heavy training, one light training, one game, and two recovery days) during their regular season. The average EI throughout the week for all 15 players was 2158 ± 87 kcal. There were no significant differences between days, but the lowest EI (1921 ± 227 kcal) occurred on the mid-week recovery day and the highest on game day (2336 ± 231 kcal). The average TDEE was 2286 ± 168 kcal (~6% > EI). The mean energy availability (EA) over the 7-day period was 31.1 ± 3.6 kcal/kg FFM/day for the group. Of the players, 14% were in the optimal EA range (>45 kcal/kg FFM/day); 34% were in the moderate range (≥30–45 kcal/kg FFM/day); and 52% had a poor EA of <30 kcal/kg FFM/day. Carbohydrate (3.38 ± 0.36 g/kg/day, 45% of EI); fat (1.27 ± 0.12 g/kg/day, 37% of EI); and protein (1.38 ± 0.12 g/kg/day, 18% of EI) consumption remained similar throughout the week (p > 0.05). The players consumed 6% less energy than they expended, providing poor to moderate EA; therefore, daily carbohydrate intake recommendations were not met.     

Biochar Synthesis from Mineral- and Ash-Rich Waste Biomass,Part 1: Investigation of Thermal Decomposition Mechanism during Slow Pyrolysis

Synthesizing biochar from mineral- and ash-rich waste biomass (MWB), a by-product of human activities in urban areas, can result in renewable and versatile multi-functional materials, which can also cater to the need of solid waste management. Hybridizing biochar with minerals, silicates, and metals is widely investigated to improve parent functionalities. MWB intrinsically possesses such foreign materials. The pyrolysis of such MWB is kinetically complex and requires detailed investigation. Using TGA-FTIR, this study investigates and compares the kinetics and decomposition mechanism during pyrolysis of three types of MWB: (i) mineral-rich banana peduncle (BP), (ii) ash-rich sewage sludge (SS), and (iii) mineral and ash-rich anaerobic digestate (AD). The results show that the pyrolysis of BP, SS, and AD is exothermic, catalyzed by its mineral content, with heat of pyrolysis 5480, 4066, and 1286 kJ/kg, respectively. The pyrolysis favors char formation kinetics mainly releasing CO₂ and H₂O. The secondary tar reactions initiate from ≈318 °C (BP), 481 °C (SS), and 376 °C (AD). Moreover, negative apparent activation energies are intrinsic to their kinetics after 313 °C (BP), 448 °C (SS), and 339 °C (AD). The results can support in tailoring and controlling sustainable biochar synthesis from slow pyrolysis of MWB.     

The Effect of Pore Structure on Impact Behavior of Concrete Hollow Brick,Autoclaved Aerated Concrete and Foamed Concrete

Porous concrete is an energy absorption material, which has been widely used in civil engineering, traffic engineering and disaster reduction engineering. However, the effect of pore structure on the impact behavior of the porous concrete is lacked. In this study, a series of drop-weight impact tests were carried out on three typical types of porous concrete, i.e., concrete hollow brick (CHB), autoclaved aerated concrete (AAC) and foamed concrete (FC), to investigate the effect of pore structures on their impact behavior. For comparison, static load tests were also conducted as references. According to the damage to the samples, the developments of impact force, strain, contact stress–strain relationship and absorbed energy during drop-weight during the impact test were measured and analyzed. The results show that the ratio between the peak impact stress and compressive strength of CHB was 0.44, while that of AAC and FC increased to about 0.6, indicating that the small and uniform pore structure in AAC and FC had a higher resistance against impact load than the hollow cavity of CHB. In addition, the elastic recovery strain in AAC increased by about 0.2% and its strain at peak contact stress increased by about 160% for a comparison of CHB, implying that a small open pore structure could enhance ductility. Besides, the peak contact stress of FC was close to that of AAC during impact loading, while the strain at peak contact stress of FC increased by about 36% compared with AAC, revealing that the closed-pore structure could further enhance the deformation potential. Correspondingly, the energy absorption rates of CHB, AAC and FC were 85.9 kJ/s, 54.4 kJ/s and 49.7 kJ/s, respectively, where AAC decreased by about 58% compared with CHB, and FC decreased by about 10% compared with AAC.     

Self-adaptive integration of photothermal and radiative cooling for continuous energy harvesting from the sun and outer space

The sun (∼6,000 K) and outer space (∼3 K) are two significant renewable thermodynamic resources for human beings on Earth. The solar thermal conversion by photothermal (PT) and harvesting the coldness of outer space by radiative cooling (RC) have already attracted tremendous interest. However, most of the PT and RC approaches are static and monofunctional, which can only provide heating or cooling respectively under sunlight or darkness. Herein, a spectrally self-adaptive absorber/emitter (SSA/E) with strong solar absorption and switchable emissivity within the atmospheric window (i.e., 8 to 13 μm) was developed for the dynamic combination of PT and RC, corresponding to continuously efficient energy harvesting from the sun and rejecting energy to the universe. The as-fabricated SSA/E not only can be heated to ∼170 °C above ambient temperature under sunshine but also be cooled to 20 °C below ambient temperature, and thermal modeling captures the high energy harvesting efficiency of the SSA/E, enabling new technological capabilities.

Heating and cooling are two kinds of significant end uses of thermal energy in society, which exist in various conditions (e.g., space/water heating, space cooling, and industrial processes) and account for 51% of the total final energy consumption (1). For example, the heating and cooling of buildings are responsible for nearly 48% of the building energy consumption, increasing to be the largest individual energy expense (2). Therefore, heat and cool harvesting relying on clean techniques from renewable energy resources has drawn remarkable attention from fields of engineering to material science because it has considerable potential for global energy conservation and greenhouse emission reduction. Thermodynamically, any heat transportation and work-generation process requires a temperature gradient. The hot sun (∼6,000 K) and cold outer space (∼3 K) are the ultimate heat source and heat sink for the Earth. Theoretical analysis reveals that maximal output work can be extracted from nonreciprocal systems based on the temperature difference between the sun and Earth (∼300 K) with an ultimate solar energy harvesting efficiency limit of 93.3%, while a maximal work of 153.1 W·m⁻² can also be obtained on the basis of temperature difference between the Earth and outer space (3, 4). Thus, the sun and outer space are two significant renewable thermodynamic resources for the Earth, which can be effectively utilized for clean heat and cool collection.Photothermal (PT) is a widely used solar thermal collection method that employs solar absorbers to capture solar photons and convert them to heat. Thermal analysis reveals that a good candidate for a solar absorber should have high solar absorptivity and low thermal emissivity simultaneously for efficient solar thermal collection. Various materials, including multilayer metal/ceramic films (5, 6), photonic crystals (7, 8), and metamaterials (9, 10), have been developed for spectrally selective solar absorbers and have been used for real-world applications. Meanwhile, radiative cooling (RC) has re-elicited considerable interest in recent years because it can passively provide clean cooling without any extra energy input (11–14). The waste heat of terrestrial objects can be continuously pumped into the cold outer space, relying on the transparent atmospheric window (i.e., 8 to 13 μm). So, high emissivity within the atmospheric window of materials is necessary for efficient RC, and excellent solar reflection is also important for RC under sunshine. Thus, different materials with the tailored spectrum, such as photonic structures (15–17), structure materials (18), energy-saving paints (19–21), and even metamaterials (22–24), have been reported for passive cooling. On the potential application level, RC implementations also span a range of fields, including passive cooling of buildings (25–27), thermal management of textiles and color surfaces (28–30), atmospheric water harvesting (31), and thermoelectric generation (32, 33). Although the reported PT and RC can generate heat and cold with high efficiency through different spectrally selective materials, most of the approaches are static and monofunctional, which can only provide heating or cooling under sunlight or darkness. Therefore, the dynamical integration of PT and RC for continuously efficient heat and cool harvesting is a new topic for the energy exploitation of the sun and outer space. The tunable combination of PT and RC hybrid utilization has been recently proposed, but mechanical methods such as switching (e.g., flip action) a PT absorber and an RC emitter manually (34) or changing the optical properties of the materials through extra force stimuli (35) are preferred.Herein, a smart strategy for the dynamic combination of daytime PT and nighttime RC is proposed, corresponding to continuously efficient energy harvesting from the sun and rejecting energy to the universe. A spectrally self-adaptive absorber/emitter (SSA/E) with solar absorption of over 0.8 and emissivity modulation capability of regulating from broadband emissivity of 0.25 within the mid-infrared (MIR) region to the selective high emissivity of 0.75 within the atmospheric window is designed and fabricated for the proof of the concept. Outdoor thermal experimental results demonstrate that the SSA/E can be heated to ∼170 °C above ambient temperature in the daytime PT mode and passively cooled to ∼20 °C below ambient temperature in the nighttime RC mode. Moreover, the heat and cool energy gains of the SSA/E system are respectively predicted to be 78% and 103% larger than those of the reference system that combines static and monofunctional PT absorber and RC emitter.     

日光温室作业对蔬菜种植人员肺小气道功能的影响

目的 探讨日光温室作业对蔬菜种植人员肺小气道功能的影响。方法 选择西北地区某蔬菜种植基地作业者988人,其中以从事大田种植作业的263人作为对照组,日光温室作业的725人作为温室组,按照累积暴露水平分为低、中、高水平暴露组。测定研究对象最大呼气50%流量(MEF₅₀)、最大呼气25%流量(MEF₂₅)和最大呼气中期流量(MMEF)等肺功能指标,测定指标实测值/预计值%<65%判定为异常;3项指标中≥2项异常判定为小气道功能障碍。应用t检验、χ²检验和Logistic回归模型分析日光温室作业对小气道功能的影响。结果 温室组MEF₅₀%、MEF₂₅%和MMEF%测定平均值分别为(71.1±25.8)%、(56.4±28.5)% 和(68.6±26.0)%,均低于对照组(78.0±24.1)%、(69.0±36.4)%、(76.1±25.5)%(P<0.05)。高水平暴露组3项指标异常率分别为45.2%、73.0%和45.7%,均显著高于对照组(31.9%、54.0%、34.6%)(P<0.05),3项指标异常率随累积暴露水平的增高而升高(P_趋势<0.05)。中、高水平暴露组小气道功能障碍检出率分别为46.8%和48.6%,显著高于对照组(35.4%)(P<0.05),小气道功能障碍检出率随累积暴露水平的增高而升高(P_趋势<0.05)。校正其他可能影响因素后与对照组相比,中、高水平暴露组小气道功能障碍OR值分别为1.555和1.651,并随累积暴露水平的增高而升高(P_趋势<0.05)。结论 日光温室可能引起作业者肺小气道功能损伤,小气道功能障碍与日光温室累积暴露水平有关。     

Comparing surgical efficiencies between phacoemulsification systems: a single surgeon retrospective study of 2000 eyes

AIM: To compare under similar conditions intraoperative surgical efficiencies metrics between an active fluidics and a gravity based phacoemulsification systems. METHODS: Adult patients who were diagnosed with a cataract that compromised visual acuity inferior to 20/40 were included in the study. Patients were excluded from the study if they had a history of severe retinal disorders, clinically significant corneal endothelial dystrophy or history of corneal disease. All phacoemulsification surgeries were performed by a single surgeon. Both phacoemulsification systems used the 0.9 mm 45-degree aspiration bypass system Intrepid Balanced tip and the 0.9 mm Intrepid Ultra infusion sleeve. All cataracts were classified using the Lens Opacities Classification System III, cumulative dissipated energy (CDE) and aspiration fluids were measured in each surgery. RESULTS: Totally 2000 eyes were included in the study. Phacoemulsification was performed in 1000 (50%) eyes with an active fluid dynamics system and in 1000 (50%) eyes with a gravity-based fluidic system. Mean CDE until fracture of the lens was 1.1 and 1.9 percent-seconds and total mean CDE used was 5.6 and 7.2 percent-seconds using an active fluidics dynamics system and gravity-based fluidic system, respectively (P<0.001). Mean aspiration fluids used were 70 mL using an active fluidics dynamics system and 84 mL using a gravity-based fluidic system (P<0.001). CONCLUSION: This study evidences that surgeries performed under similar conditions (same surgeon, phaco tip and sleeve) with the active fluidics dynamics system required significantly lower CDE and aspiration fluids.