Boundary layer structure in turbulent rayleigh-bénard convection in a slim box

Logarithmic boundary layers have been observed in different regions in turbulence. However, how thermal plumes correlate to the log law of temperature and how the velocity profile changes with pressure gradient are not fully understood. Here, we perform three-dimensional simulations of turbulence in a slim-box without the front and back walls with aspect ratio, width:depth:height=L:D:H=1:1/6:1width:depth:height=L:D:H=1:1/6:1 (respectively corresponding to xx, yy and zz coordinates), in the Rayleigh number Ra=[1×10^8,1×10^10]Ra=[1×10^8,1×10^10] for Prandtl number Pr=0.7Pr=0.7. To investigate the structures of the viscous and thermal boundary layers, we examine the velocity profiles in the streamwise and vertical directions (i.e. UU and WW) along with the mean temperature profile throughout the plume-impacting, plume-ejecting, and wind-shearing regions. The velocity profile is successfully quantified by a two-layer function of a stress length, e^+u=e^+0(z^+)3/2[1+(z^+/z^+sub)4]^1/4eu+=e^+0(z+)3/2[1+(z+/zsub+)4]1/4, as proposed by She et al.(J Fluid Mech, 2017), though it is neither \pb type nor logarithmic. In contrast, the temperature profile in the plume-ejecting region is logarithmic for all simulated cases, being attributed to the emission of thermal plumes. The coefficient of the temperature log-law, AA, can be described by composition of the thermal stress length ■■θ0■θ0■ and the thicknesses of thermal boundary layer z■subzsub■ and z?bufzbuf■, i.e. A■z?sub/(■■θ0z■buf3/2)A■zsub?/(■θ0■zbuf^3/2). The adverse pressure gradient responsible for turning the wind direction contributes to intensively emitting plumes and the logarithmic temperature profile at the plume-ejecting region. The Nusselt number scaling and the local heat flux in the slim box are consistent with previous results of the confined cells. Therefore, the slim-box RBC is a preferable system for investigating in-box kinetic and thermal structures of turbulent convection with the large-scale circulation in a fixed plane.

Numerical study of heat-transfer in two-and quasi-two-dimensional Rayleigh–Bénard convection

A detailed comparative numerical study between the two-dimensional（2 D） and quasi-two-dimensional（quasi-2 D）turbulent Rayleigh–B＇enard（RB） convection on flow state, heat transfer, and thermal dissipation rate（TDR） is made. The Rayleigh number（Ra） in our simulations ranges up to 5×10^10 and Prandtl number（Pr） is fixed to be 0.7. Our simulations are conducted on the Tianhe-2 supercomputer. We use an in-house code with high parallelization efficiency, based on the extended PDM–DNS scheme. The comparison shows that after a certain Ra, plumes with round shape, which is called the ＂temperature islands＂, develop and gradually dominate the flow field in the 2 D case. On the other hand, in quasi-2 D cases, plumes remain mushroom-like. This difference in morphology becomes more significant as Ra increases, as with the motion of plumes near the top and bottom plates. The exponents of the power-law relation between the Nusselt number（Nu） and Ra are 0.3 for both two cases, and the fitting pre-factors are 0.099 and 0.133 for 2 D and quasi-2 D respectively,indicating a clear difference in magnitude of the heat transfer rate between two cases. To understand this difference in the magnitude of Nu, we compare the vertical profile of the horizontally averaged TDR for both two cases. It is found that the profiles of both cases are nearly the same in the bulk, but they vary near boundaries. Comparing the bifurcation height zb with the thermal boundary layer thickness dq, it shows that zb 〈 δθ（3 D） 〈 δθ（2 D） and all three heights obey a universal power-law relation z ~Ra^-0.30. In order to quantify the difference further, we separate the domain by zb, i.e., define the area between two zb（near top and bottom plates respectively） as the ＂mid region＂ and the rest as the ＂side region＂, and integrate TDR in corresponding regions. By comparing the integral it is found that most of the difference in TDR between two cases, which is connected to the heat transfer rate, occurs within the thermal boundary layers. We also compare the ratio of contributions to total heat transfer in BL–bulk separation and side–mid separation.

慢性阻塞性肺疾病并骨质疏松患者Th17及Treg相关细胞因子水平的变化

目的探讨辅助性T细胞17(Th17)及调节性T细胞(Treg)相关细胞因子IL-17A、IL-10在慢性阻塞性肺疾病(COPD)并骨质疏松患者的表达情况及意义。方法选取2019年6月~2021年12月于我院就诊的76例稳定期COPD患者(COPD组)及同期38例健康体检者(对照组)为研究对象。COPD组患者根据骨密度结果分为骨质疏松组(n=31)和非骨质疏松组(n=45),测定所有研究对象入组当天血清IL-17A、IL-10水平并进行统计学分析。结果①76例COPD患者中31例合并骨质疏松,占比41%。与对照组相对,COPD组患者IL-17A明显升高,但IL-10显著降低(均P<0.05);②与COPD非骨质疏松组患者相比,骨质疏松组血清IL-17A水平明显升高,但IL-10水平显著降低(均P<0.05)。COPD骨质疏松组患者血清IL-17A水平随肺功能的下降而逐渐升高,但IL-10水平逐渐降低;③腰椎及股骨颈BMD与血清IL-17A水平呈负相关,但与IL-10水平及FEV_(1)(%)呈正相关(均P<0.05)。结论COPD、COPD并骨质疏松患者均存在IL-17A及IL-10表达失衡,血清IL-17A及IL-10水平与肺功能及骨密度相关。

Strong coupling between height of gaps and thickness of thermal boundary layer in partitioned convection system

A direct numerical simulation(DNS) method is used to calculate the partitioned convection system with Ra number ranging from 10^7 to 2×10^9.Using the boundary layer thickness to normalize the height of gaps d, we find a strong consistency between the variation of the TD number(the average value of the temperature in each heat transfer channel is averaged after taking the absolute values) with the change of the height of gaps and the variation of the TD number with the change of Ra number in partitioned convection.For a given thickness of partition, heights of gaps are approximately equal to 0.5 or 1 time of the thermal boundary layer thickness λθ at different Ra numbers.TD number representing temperature characteristics is almost the constant value, which means that TD number is a function of d/λθ only.Analysis of local temperature field of area in gaps shows that the temperature distribution in the gaps are basically the same when d/λθ is certain.The heat transfer Nu number of the system at d/λθ≈ 0.5 is larger than that of d/λθ≈ 1, both of them have the same scaling law with Ra number and Nu^Ra^0.25.

A High-Performing and Cost-Effective SNP Genotyping Method Using rhPCR and Universal Reporters

We have developed a novel dual enzyme chemistry called rhAmp&reg;SNP genotyping based on RNase H2-dependent PCR (rhPCR) that provides high signal and specificity for SNP analysis. rhAmp SNP genotyping combines a unique two-enzyme system with 3’ end blocked DNA-RNA hybrid primers to interrogate SNP loci. Activation of the blocked primers occurs upon hybridization to its perfectly matched target, which eliminates or greatly reduces primer dimers. A thermostable hot-start RNase H2 cleaves the primer immediately 5’ of the ribose sugar, releasing the blocking group and allowing primer extension. PCR specificity is further improved with the use of a mutant Taq DNA polymerase, resulting in improved allelic discrimination. Signal generation is obtained using a universal reporter system which requires only two reporter probes for any bi-allelic SNP. 1000 randomly selected SNPs were chosen to validate the 95% design rate of the design pipeline. A subsampling of 130 human SNP targets was tested and achieved a 98% call rate, and 99% call accuracy. rhAmp SNP genotyping assays are compatible with various qPCR instruments including QuantStudioTM 7 Flex, CFX384TM, IntelliQube&reg;, and Biomark HDTM. In comparison to TaqMan&reg;, rhAmp SNP genotyping assays show higher signal (Rn) and greater cluster separation, resulting in more reliable SNP genotyping performance. The rhAmp SNP genotyping solution is suited for high-throughput SNP genotyping applications in humans and plants.

Effects of Prandtl number in two-dimensional turbulent convection

We report a numerical study of the Prandtl-number(Pr)effects in two-dimensional turbulent Rayleigh-Bénard convection.The simulations were conducted in a square box over the Pr range from 0.25 to 100 and over the Rayleigh number(Ra)range from 10^(7) to 10^(10).We find that both the strength and the stability of the large-scale flow decrease with the increasing of Pr,and the flow pattern becomes plume-dominated at high Pr.The evolution in flow pattern is quantified by the Reynolds number(Re),with the Ra and the Pr scaling exponents varying from 0.54 to 0.67 and-0.87 to-0.93,respectively.It is further found that the non-dimensional heat flux at small Ra diverges strongly for different Pr,but their difference becomes marginal as Ra increases.For the thermal boundary layer,the spatially averaged thicknesses for all the Pr numbers can be described byδθ~Ra^(-0.30) approximately,but the local values vary a lot for different Pr,which become more uniform with Pr increasing.

通心络联合阿托伐他汀对颈动脉粥样斑块的影响分析

目的探讨通心络联合阿托伐他汀对颈动脉粥样斑块的影响分析。方法选取广东省佛山市南海区桂城医院2020年6月-2021年6月收治的80例颈动脉粥样斑块患者作为研究对象,以随机数字表法进行分组,分为试验组和对照组,每组各40例,对照组采用阿托伐他汀治疗,试验组在对照组基础上加用通心络治疗,评价两组患者的血脂水平、炎症指标、颈动脉内膜中层厚度(IMT)和斑块积分。结果试验组患者血脂水平、炎症因子水平、IMT和斑块积分与对照组比较,差异均有统计学意义(P<0.05)。结论通心络联合阿托伐他汀干预颈动脉粥样斑块的临床疗效显著,不仅能够降低患者血脂水平和炎症指标,还能抑制颈动脉内膜中层增厚和斑块形成,值得临床推广。

Characteristics of temperature fluctuation in two-dimensional turbulent Rayleigh-Bénard convection

We study the characteristics of temperature fluctuation in two-dimensional turbulent Rayleigh–Benard convection in´a square cavity by direct numerical simulations.The Rayleigh number range is 1×10^(8)≤Ra≤1×10^(13),and the Prandtl number is selected as Pr=0.7 and Pr=4.3.It is found that the temperature fluctuation profiles with respect to Ra exhibit two different distribution patterns.In the thermal boundary layer,the normalized fluctuationθrms/θrms,max is independent of Ra and a power law relation is identified,i.e.,θrms/θrms,max∼(z/δ)0.99±0.01,where z/δis a dimensionless distance to the boundary(δis the thickness of thermal boundary layer).Out of the boundary layer,when Ra≤5×10^(9),the profiles ofθrms/θrms,max descend,then ascend,and finally drop dramatically as z/δincreases.While for Ra≥1×10^(10),the profiles continuously decrease and finally overlap with each other.The two different characteristics of temperature fluctuations are closely related to the formation of stable large-scale circulations and corner rolls.Besides,there is a critical value of Ra indicating the transition,beyond which the fluctuation hθrmsiV has a power law dependence on Ra,given by hθrmsiV∼Ra−0.14±0.01.

Fever of unknown origin as the first manifestation of Erdheim-Chester disease

Erdheim-Chester disease (ECD) is an uncommon non-Langerhans cell histiocytosis that affects multiple body systems and can present clinically in a myriad of ways. We report the case of a 29-year-old man presented with fever and diffuse bone pain. Physical examination showed bilateral and symmetrical long bone pain, especially the knees. Radiographs showed multiple mixed bone lesions with sclerotic and lytic areas of the femora, tibiae, and fibula. Biopsy of the tibial area displayed foamy lipid-laden histiocytes, confirming the diagnosis of ECD.

Projection of China's Near- and Long-Term Climate in a New High-Resolution Daily Downscaled Dataset NEX-GDDP

The projection of China＇s near- and long-term future climate is revisited with a new-generation statistically down- scaled dataset, NEX-GDDP （NASA Earth Exchange Global Daily Downscaled Projections）. This dataset presents a high-resolution seamless climate projection from 1950 to 2100 by combining observations and GCM results, and re- markably improves CMIP5 hindcasts and projections from large scale to regional-to-local scales with an unchanged long-term trend. Three aspects are significantly improved： （1） the climatology in the past as compared against the ob- servations; （2） more reliable near- and long-term projections, with a modified range of absolute value and reduced inter-model spread as compared to CMIP5 GCMs; and （3） much added value at regional-to-local scales compared to GCM outputs. NEX-GDDP has great potential to become a widely-used high-resolution dataset and a benchmark of modem climate change for diverse earth science communities.

Genetic polymorphisms of 21 STR loci of Goldeneye^(TM) DNA ID 22NC kit in five ethnic groups of China

Dear Editor,Short tandem repeats(STRs),polymorphic DNA regions with a variable number of repeated units(2–6 base pairs),are attractive to forensic applications such as human identification and parentage testing[1].Nowadays,most of the commercial STR kits are designed based on STRs from the combined DNA index system(CODIS),European Standard Set(ESS),expanded CODIS,and extended ESS[2].In this study,we evaluated 21 STRs from GoldeneyeTM DNA ID 22NC kit(PeopleSpot Inc.,Beijing,China),which including 20 polymorphic non-CODIS STR loci(i.e.D1S1656,D2S441,D3S1744,D3S3045,D4S2366,D5S2500,D6S477,D7S1517,D7S3048,D8S1132,D10S1248,D10S1435,D11S2368,D13S325,D14S608,D15S659,D17S1290,D18S535,D19S253,D22GATA198B05)and a CODIS STR locus(D3S1358),in five ethnic groups(i.e.Eastern Han,Ningxia Hui,Xinjiang Uygur,Xizang Tibetan,and Inner Mongolia Mongolian)of China.The forensic genetic investigation of above loci may provide more genetic information in complex kinship testing and population studies[3,4].