The Morphology of the Primary Dental Arch of Chinese Children in Shijiazhuang-City Part-I: Research concerning the size of the primary tooth crown, primary dental arch and the condition of primary occlusion

The purpose of this study was to investigate the size of the primary tooth crowns, primary dental arches, standard values and frequency distribution of primary occlusion in Chinese children. With the cooperation of a kindergarten in Shijiazhuang-city, China, the dental plasters from 55 children (36 boys and 19 girls, age range from 3-6 years old) with normal primary occlusion were collected. Because of different growth rates of the children, these children were divided into two groups, one comprising children less than 5 years old and the other of 5 years old or older. According to the method that the Japanese Society of Pediatric Dentistry reported, the data were statistically analyzed and compared to Japanese children. The results were summarized as follows: 1. Except lower primary lateral incisors, the values of the mesio-distal width of primary crowns of each tooth were significantly larger for boys than for girls in all tooth types. Also the Chinese children were inclined to show smaller mesio-distal tooth crown width than those of the Japanese children in all types of teeth. 2. Compared with the Japanese children, the Chinese children were inclined to show smaller primary dental arch length both in the maxilla and the mandible. But in the senior group, the Chinese girls were inclined to show smaller primary dental arch width than their Japanese female counterparts. On the contrary, the Chinese children tended to show larger dimensioned primary dental arch height than those of the Japanese children. 3. Though spaces between teeth (primate and growth spaces) were found in the Chinese children, the frequency was lower than that of the Japanese children. 4. The frequency of terminal plans in the Chinese children was 41.8% in the vertical type, 6.4% in the distal-step type and 51.8% in the mesial step type. 5. The primary canines occlusal relationship in the Chinese children was 63.1% in type I, 13.6% in type II and 23.7 in type III

安徽省森林碳储量现状及固碳潜力

为阐明安徽省不同林龄的森林生态系统的碳储量现状,以及现有自然环境条件下顶极森林生态系统的固碳潜力,采用野外样地调查和BIOME4模型方法对此进行研究。安徽省森林生态系统的现状总碳储量为714.5 Tg C,其中植被碳402.1 Tg C、土壤碳312.4 Tg C。从幼龄林至过熟林的生长过程中,森林生态系统的总碳密度和植被碳密度都呈现增长趋势。但土壤碳密度从幼龄林至近熟林阶段呈增加趋势,近熟林以后出现减少趋势。安徽省幼龄林和中龄林占森林总面积的75%,若幼、中龄林发展到近熟林阶段,将增加125.4 Tg C。BIOME4模拟显示:当森林发展到气候顶极森林时,安徽省森林生态系统将增加245.7 Tg C,即总固碳潜力包括植被固碳153.7 Tg C,土壤固碳92.0 Tg C

Litter Accumulation on the Ground Surface in Evergreen Broadleaved Forests in Okinawa

本調査は, 沖縄の天然生常緑広葉樹林のリターの現存量について, 22箇所で調査を行い, 地形, 土壌型及び林分構造との関係を検討したものである。調査の結果を要約すると, およそ次の通りである。1.天然生常緑広葉樹林のリター現存量は約12ton/haで, リュウキュウマツ林の17ton/ha(今回, 5箇所で調査)に比べるとやや少ない。また, 暖帯地方のナラ, カシ林とはほぼ近似した値を示すが, 冷温地方のブナ林と比較すると, その約40%程度である。2.全リター量の内, 葉リター, 枝リター, 幹リター及び(F+H)層の占める割合は, それぞれ36%, 22%, 20%及び22%となっていて, 葉リターが最も多く, それ以外は殆ど類似している。3.リター現存量は, 土壌型と密接な関係を示し, 土壌の乾燥したY_B型で多く, 土壌水分の比較的多いY_C型では少なくなる傾向がある。4.リター現存量と林分構造との関係をみると, 平均直径, ha当たり本数及び断面積とは比較的高い相関が認められるが, そのほかの因子とははっきりした傾向を示さない。5.リターの分解速度を表す(F+H)/L_lの値を比較すると, 寒冷地方で大きく, 暖帯, 亜熱帯地方で小さくなっている。すなわち, 寒冷地方で分解速度は遅く, 暖帯, 亜熱帯地方で速いといえる。The accumulation of litter on forest floor was studied at 27 sites in Experimental Forest, University of the Ryukyus at Yona, Okinawa. The litter accumulation on forest floor amounted, averagely, to 12.02t/ha in evergreen broadleaved forest, lower than that in Ryukyu pine forest, which amounted to 17.25t/ha. The leaf litter, branch litter, wood litter and (F+H) layer amounted for about 36%, 22%, 20% and 22% of the total litter accumulation, respectively. The litter accumulation was strongly affected by soil type or soil moisture. But, the effect of the stand structure over litter accumulation was complicated. The result from the investigation demonstrated that basal area, mean d. b. h. and density of stand appeared to have certain tendency to affect on litter accumulation. The mean ratio of (F+H) to L_l in evergreen broadleaved forest was 0.38,lower than that in pine forest, which was 0.73. The estimated decomposition rate of litter was very rapid as those in other forests in Japan

二维GaAs基光子晶体微腔的制作与光谱特性分析

研究了以InAs量子点为有源区的二维GaAs基光子晶体微腔的设计与制作,测试并分析了室温下微腔的光谱特性.观察到了波长约为1137nm,谱线半高宽度约为1nm的尖锐低阶谐振模式发光峰.我们比较了不同刻蚀条件下光子晶体微腔的发光谱线,结果表明空气孔洞截面的垂直度是影响光子晶体微腔发光特性的重要因素之一.通过调节干法刻蚀工艺,改变空气孔半径与晶格常数的比率,可以在较大范围内调节谐振模式发光峰位置,达到谐振模式与量子点发光峰调谐的目

用二异丙酮溶剂萃取~(233)Pa(Ⅴ)

用233Pa作示踪剂,苯作稀释剂,研究了二异丙酮(Di-iso-propyl-ketone)对Pa的溶剂萃取行为。分析了萃取效率与震荡时间、不同种类的无机酸浓度和萃取剂浓度的关系及F-对Pa溶剂萃取的影响。结果表明,二异丙酮是萃取Pa的一种优良的萃取剂;二异丙酮-盐酸体系适用于Pa的萃取研究