Signatures of a gapless quantum spin liquid in the Kitaev material Na3_3Co2−x_{2-x}Znx_xSbO6_6

The honeycomb-lattice cobaltate Na$_3$Co$_2$SbO$_6$ has recently been proposed to be a proximate Kitaev quantum spin liquid~(QSL) candidate. However, non-Kitaev terms in the Hamiltonian lead to a zigzag-type antiferromagnetic~(AFM) order at low temperatures. Here, we partially substitute magnetic Co$^{2+}$ with nonmagnetic Zn$^{2+}$ and investigate the chemical doping effect in tuning the magnetic ground states of Na$_3$Co$_{2-x}$Zn$_x$SbO$_6$. X-ray diffraction characterizations reveal no structural transition but quite tiny changes on the lattice parameters over our substitution range $0\leq x\leq0.4$. Magnetic susceptibility and specific heat results both show that AFM transition temperature is continuously suppressed with increasing Zn content $x$ and neither long-range magnetic order nor spin freezing is observed when $x\geq0.2$. More importantly, a linear term of the specific heat representing fermionic excitations is captured below 5~K in the magnetically disordered regime, as opposed to the $C_{\rm m}\propto T^3$ behavior expected for bosonic excitations in the AFM state. Based on the data above, we establish a magnetic phase diagram of Na$_3$Co$_{2-x}$Zn$_x$SbO$_6$. Our results indicate the presence of gapless fractional excitations in the samples with no magnetic order, evidencing a potential QSL state induced by doping in a Kitaev system.Comment: 10 pages, 5 figure

Analysis of Natural Ventilation Performance Gap between Design Stage and Actual Operation of Office Buildings

Suitable natural ventilation in office buildings can not only reduce energy consumption of air conditioning, but also improve indoor air quality. In the architectural design stage, the effect of natural ventilation design is mainly simulated by CFD simulation software for indoor air speed, pressure, and age of air, etc.. However, during the actual building operation, the indoor natural ventilation effect will be affected by many factors, such as surrounding buildings, indoor layout, window position and open-close status, human behavior, etc., and the natural ventilation performance between design stage and actual operation is often different. In this paper, a typical office building was selected and FloVENT software was used to quantitatively analyse the influence of surrounding buildings, indoor layout, door/window opening conditions on indoor natural ventilation. Field measurement of indoor air flow rates in typical positions in office were carried out under different circumstances. In order to reduce the instantiate influence of outdoor wind speeds, a new index named Wind Speed Ratio(WSR) is put forward.Through comparative analysis of simulated data and measured data. the gap degree in natural ventilation performance between design stage and operation operation is discussed, and results show that the relative errors of the WSR, which could be considered to reflect the performance gap, are about 78.0%, 28.7% and 150% respectively, under corresponding condition settings of surrounding buildings, indoor layout, and door/window opening

Ecological renovation process of Nanjing’s housing stock built between 1840 and 1949, China

Numerous in number and mostly still in use, buildings built between 1840 and 1949 are valuable assets in the rapid development and renovation of Chinese cities. However, due to lack of maintenance and being inhabited mainly by the elderly and people with low incomes, many of these buildings are in poor condition and have much higher possibilities of being demolished. The objectives of ecological renovation presented in this paper are to improve building performance and to achieve higher levels of comfort and lower levels of energy consumption. The housings in Zhong-nong-li block in Nanjing are used as an example in this paper to show how a strategy of “basic” renovation and “thorough” renovation is used in the ecological renovation of housing stock between 1840 and 1949 in China. The paper demonstrates that these are very practical steps for this building stock in China and could not only help to balance social and economic factors in practice, but also improve the living conditions of the residents, and endow the old houses with a new, long life. Numerical simulations of the natural day lighting and ventilation situations before and after renovation are made to show the improvement in building performance after renovation

Field survey on energy consumption due to hot water supply and cooking in Nanjing and Hefei, China

A field survey on energy consumption by hot water supply and cooking was conducted in two cities in China, Nanjing, and Hefei. In each city, 5 housing complexes were selected, and approximately 100 or 200 residential units were selected from each of them. The following items were surveyed: (1) fundamental information, such as number of family members, data on residents, etc., (2) bathing style, and (3) frequency of cooking and cooking time. Most of the residents take showers seven times a week in the summer, but less frequently in the winter. In contrast, the frequency of taking baths increases to several times a week during the winter, compared with 0 or 1 times a week in the summer. These results differ slightly depending on the heating and cooling systems used in the houses. The frequency with which people cook in their own houses ranges from 4 to 7 times a week, which means that “eating out” is relatively frequent, although the result differs significantly among the housing complexes. Distribution of the cooking time has usually two peaks at 20 to 30 min and 50 to 60 min (or 30 to 40 min and longer than 60 min) for lunch and dinner, respectively. The high energy consumption for cooking might be due to the long cooking time

Quantitative evaluation of deterioration in west wind-room in the Palace Museum

The Palace Museum in Beijing is a world cultural heritage site. Surviving nearly 600 years, heritage buildings in the Palace Museum have been deteriorated by salting out, exfoliation, cracking and so on. For the purpose of quantitative evaluation on current environment risks and proposing conservation approaches, heat and moisture transfer on buildings was simulated by a numerical model and the West Wind-room in the Hall of Mental Cultivation (Yangxin Dian) in the Palace Museum was taken as example. The results indicated that to reduce freezing-thawing cycles, the indoor temperature should be increased during December to early February. Indoor temperature and humidity should be controlled to a more stable and lower level to decrease the damaging from salt crystallization and hydration. And attention should be paid to more salting-out resulted by evaporation increase in spring and autumn. The results will provide support to environment control of Chinese traditional buildings

Establishment of platelet donor registry improves the treatment of platelet transfusion refractoriness in Guangzhou region of China

Platelet transfusion refractoriness (PTR) is the major complication of long-term platelet supportive care. To improve the effectiveness of platelet transfusion therapy in PTR patients, we aimed to establish a platelet donor registry in our region (Guangzhou, China) by typing the human leukocyte antigen (HLA) and human platelet antigen (HPA). Blood donors (n = 864) from our population were genotyped for HLA-A, HLA-B and HPA systems by polymerase chain reaction amplification with sequence-specific primer(PCR-SSP) techniques. Using this cohort, we compared the results of platelet transfusions (matched vs. random) in 23 patients with PTR. Matched platelets were selected either by HLA antigen matching or by HLA antibody matching, as predicted by antibody specificity prediction (ASP) analysis. Significantly higher platelet recovery (PPR) values were obtained with HLA-matched platelets in comparison with random platelets. No significant difference in PPR was observed between HLA matching and ASP methods. In two patients, platelet-specific alloantibodies (alloabs) (anti-HPA-3b and anti-HPA-5b) were detected besides HLA class I alloabs. Transfusion with HLA- and HPA-compatible platelets in both the patients resulted in significantly higher PPR when compared with HLA-compatible platelet transfusion alone. In this study, we demonstrated that the establishment of an HLA- and HPA-typed platelet aphaeresis donor registry is useful to improve the treatment outcome of PTR patients and to maintain a long-term platelet transfusion strategy. © 2010 British Blood Transfusion Society.link_to_subscribed_fulltex

Distribution of MICA haplotypes in a Chinese Han population

The MICA gene encodes nonclassical major histocompatibility complex class I molecules, centromeric to HLA-B and telomeric to HLA-DRB1. The MICA genes are polymorphic. The immune response against MICA may correlate with a decrease in graft survival after transplantation. However, data on the frequency of MICA polymorphisms in different populations are limited. In this study, we determined MICA allelic frequencies in a Han population living in Guangdong Province in south China. A total of 15 MICA alleles were identified using sequence-based typing. The most frequent allele was MICA*010 (22.22%), followed by MICA*002:01(18.56%), MICA*008:01(16.32%), and MICA*019(14.93%). The MICA null gene (MICA*Del) exhibited a frequency of 1.743% in this population. MICA and HLA, MICA-HLA-B, and MICA-HLA-A/HLA-B/HLA-DRB1 haplotype frequencies were estimated. The most common 2-, 3- and 4-locus haplotypes were HLA-B*40:01-MICA*008:01 (13.70%), HLA-A*11:01-B*40:01-MICA*008:01(8.25%), and HLA-A*33:03-B*58:01-DRB1*03:01-MICA*002:01(5.22%). A new MICA allele, MICA*061, was identified and appears to be evolutionarily related to MICA*012:01. This study provides high-resolution information on the distribution of haplotypes with MICA, HLA-A, HLA-B, and HLA-DRB1 in China. This information should help determine the mechanisms underlying diseases and allotransplant rejection associated with MICA polymorphisms in the southern Chinese Han population. © 2012 American Society for Histocompatibility and Immunogenetics.link_to_subscribed_fulltex