Crystal Structure of Natural Non-metamict Ti- and Fe^(2+)-rich Chevkinite-(Ce)

The crystal structure of non-metamict Ti- and Fe2+-rich chevkinite-(Ce) has been redetermined with the single -crystal sample collected from Bayan Obo, Inner Mongolia, China. The chemical formula of the sample is Ce4Fe2Ti3Si4O22. The crystals are monoclinic with the unit cell parameters a = 13.4656(15) ?, b = 5.7356(6) ?, c = 11.0977(12) ?, β= 100.636(2)o, V = 842.39 (16) ?3 and Z = 2. The structures of Ti- and Fe2+-rich chevkinite-(Ce) were refined with space groups P21/a and C2/m. Least-squares refinement results show that both structural models of Ti- and Fe2+-rich chevkinite-(Ce) are very good, R[F2>2σ(F2)] =0.027 with P21/a and R[F2>2σ(F2)] =0.021 with C2/m. In order to illustrate the relationship between the two space groups P21/a and C2/m, the distribution of diffraction intensities was inspected. Pseudo extinction was found, i.e., reflections with h+k=2n are systematically strong, while those with h+k=2n+1 are weak. By neglecting the systematically weak (h+k=2n+1) reflections the space group becomes C2/m. There is a mirror plane in the C2/m perpendicular to the b axis. However, oxygen atoms in the P21/a model are of a symmetrical relationship with the corresponding pseudo mirror plane. It is concluded that the crystal structure of non-metamict Ti- and Fe2+-rich chevkinite-(Ce) is a superstructure with the space group of P21/a, which is of pseudo symmetry corresponding to the space group C2/m.

New Investigation on the Space Group of Chevkinite

Chevkinite specimen from a rare-earth mineral deposit in Sichuan, southwest of China have been studied in detail by means of transmission electron microscope (TEM).The selected area electron diffraction (SAED)and convergent beam electron diffraction (CBED) patterns , obtained from different crystal zone axis direction , proved coincidently that the space group of chevkinite is C2/m . Fringe lattice image observation showed the mineral crystal is structurally uniform in microscale , and it is an ideal specimen for electron diffraction analysis . The mineral studied here is similar to the one from Bayan Obo , Inner Mongolia , China , in chemical composition and REE distribution . The chemical formula of the crystal is (Ce , La ,… , Ca) 4 Fe2+ (Fe, Ti, Nb) 2 O8 (Si2O7)2 From our study , we come to the conclusion that the space group of the natural chevkinite is C2/m , instead of P21/a as synthetic one . Up to now , chevkinite compositionally similar to the synthetic one , in which the complete replacements of Ce , La by Nd and Fe by Mg or Co occur , has not been discovered in nature . So we suggest that the name for synthesized chevkinite should be further discussed .

Crystal Chemistry of Iron in Non-Metamict Chevkinite-(Ce): Valence State and Site Occupation Proportions

The ideal formula for chevkinite can be expressed as A4BC2D2Si4O22. It is important to determine the valence state and site occupation proportions for Fe among the B, C, and D octahedral sites as it may help to identify different species in the chevkinite group. Non-metamict chevkinite-（Ce） from Mianxi alkali feldspar-granite, Sichuan Province, China, was investigated using Moessbauer spectroscopy. The Fe^3＋/∑Fe ratio was 39.2%. A significant increase of Fe^3＋ occured during metamictization and annealing for chevkinite-group minerals. In metamict samples Fe tended to lower coordination, According to the correlation between bond length and isomer shift （IS）, the quadrupole doublets with IS = 1.10 and 0.94 mm·s^-1 can be assigned to Fe^2＋ in the B and C octahedral sites, respectively. Based on the correlation between octahedral distortion and quadrupole splitting （QS）, the quadrupole doublets with QS = 0.86 and 0.77 mm·s^-1 can be assigned to Fe^3＋ in the C and D sites, respectively. The simplified formula can be revised as： Ce4Fe^2＋ （Ti, Fe^2＋, Fe^3＋ ）2（Ti, Fe^3＋ ）2Si4（O,OH）22. It indicated that the non-metamict chevkinite-（Ce） belonged to Fe^2＋ end member of the chevkinite group because Fe^2＋ was the predominant component in the B site.

Hydroxyl groups in nonmetamict chevkinite-(Ce): a crystal chemical discussion

The minerals of chevkinite group were commonly considered to be anhydrous minerals. The infrared absorption spectrum of natural nonmetamict chevkinite-（Ce） from the aegirine-alkali granite, Miannlng, Sichuan Province, China, exhibited two broad peaks in the 3600-2800 cm^-1 region owing to the OH stretching. The corresponding H20 content required for the charge balance in formula was 1.27%. The O-H. … O bond lengths maight cover from 0.2658 to 0.2794 nm by the correlated OH stretching energies. An electrostatic charge balance for chevkinite-（Ce） based on the assigned site-population from chemical data was calculated without the hydrogen contribution. The resulting empirical bond-valence sum on 06, 08, 02, 03, 05, and 04 ranged from 1.73 to 1.95 vu. The partial substitution of O by OH may occur in four atom sites： 06, 02, 04, and 05. The small differences in the bond-valence sums between the supposed donors and acceptors may mean a mixed donor/acceptor role of the involved oxygen atoms. The IR spectral features between 3394 and 3035 cm-1 consisted of various hydrous species at different structural sites and orientations. The OH groups in the chevkinlte-（Ce） appeared to be involved in local charge imbalance in the structure and to be present when the mineral crystallized hydrothermally.

Tobacco use among population sub-groups: A gender analysis

Women comprise 20% of world’s billion smokers. Especially troubling is raising prevalence of tobacco use among girls. In fact, it is expected that 20% of women in developing/developed countries will be smokers by 2025. This study analytically compares knowledge, attitudes, and practices of tobacco use, by gender, among 4 sub-populations in Alexandria, Egypt. Methods: A cross sectional approach was used for 4 subgroups (high school students, university students, shopping malls/clubs’ attendees, employees of health-related facilities), 1000 each (total sample size = 4000). A modified version of WHO questionnaire was used for data collection. Results: Smoking prevalence was generally higher among males (29%-44%) compared to females (2% - 9%) in the studied groups. Cafeterias were preferable smoking places for both genders, especially among high school/university students. Most smokers in the 4 subgroups reported that most or all their friends were smokers. Mean knowledge scores were found to be higher among male employees/high school students, compared to females in the same sub-groups. Mean attitude scores towards smoking were higher among females (i.e. against smoking) in the 4 sub-samples. Conclusion & Recommendations: Tobacco use among males is generally higher among males, but females seem to be catching up. Social gatherings seem to attract many youngsters, of both genders, to smoke in public, especially waterpipe (which is a growing epidemic of tobacco use in our communities). Mass community- and gender-based health awareness campaigns are needed, using different channels, including school-based health education interventions, at the earliest age possible.

四川昌北稀土矿床中的硅钛铈矿

1986年笔者在四川昌北稀土矿床中发现一种结晶完好的硅钛铈矿。矿物物理性质与我国白云鄂博产出者相似。矿物组分中富铌。晶体化学式为(Ce,La,Nd…Ca)_4Fe^(2+)(FeTiNb)_2Ti_2O_8[Si_2O_7]_2。经四圆单晶衍射和电子衍射测得晶胞参数相同,α=13.385(2),b=5.742(1),c=10.059(2),β=100.60(0.01)°,空间群C 2/m。对矿物晶体定向带轴进行了高分辨晶格象观测。

富铁硅钛铈矿的晶体化学

通过电子探针分析和晶体结构测定 ,证明四川冕宁碱性花岗岩中的天然非变生铁硅钛铈矿 ,以富含铁、稀土和铌为特征 ,FeO(全铁 )质量分数为 10 .97%～ 11.5 9% ,Ce2 O3变化范围为 2 3 %～ 2 5 % ,Nb2 O5为 1.5 3 %～ 2 .10 % ;化学式中存在A型和 (B +C)型阳离子缺失 ;具有C2 /m空间群 (R =2 .41% ) ;晶胞参数为 :a =1.3 45 6( 3 )nm ,b =0 .5 72 80 ( 10 )nm ,c =1.10 83 ( 2 )nm ,β =10 0 .60 ( 3 )° ,V =0 .83 97( 3 )nm3,Z =2。富铁硅钛铈矿的晶体结构由 2种层组成 ,一是由Si2 O7基团和B -八面体构成的层 ,一是由C -八面体层构成的层 ;2种层均平行ab平面 ,沿c轴交替排列构成三维格架。稀土离子位于双硅酸根和八面体层之间 ,形成 ( 8+3 )配位的A( 1)多面体和 10配位的A( 2 )多面体。Fe和Ti呈部分有序分布于B ,C( 1) ,C( 2A)和C( 2B)位置中。

牦牛坪矿-(Ce):一种新发现的稀土元素矿物

牦牛坪矿- (Ce)属硅钛铈矿亚族的新成员,发现于四川牦牛坪稀土矿床的碳酸岩、伟晶碳酸岩和碱性岩等矿脉中。与已知的同亚族矿物相比,新矿物要么是chevkinite - (Ce)B位上的Fe3 + 类似物,要么同时是polyakovite- (Ce)B位和C位上的Fe3 + 类似物。牦牛坪矿- (Ce)直接从一类富F、水和REE的岩浆 热液过渡阶段的成矿流体中结晶所成。新矿物得名于产地和稀土元素中Ce居优。牦牛坪矿- (Ce)及其命名,已获国际矿物协会新矿物及矿物命名委员会投票批准。

新矿物丁道衡矿-(Ce):珀硅钛铈矿的同质多象体和硅钛铈矿亚族C(1)位上的钛类似矿物

丁道衡矿-（Ce）：（Ce，La）4Fe^2＋（Ti，Fe^2＋，Mg，Fe^3＋）2Ti2Si4O22，理想的结构化学式Ce2Ce2Fe2＋Ti2Ti2Si4O22，单斜晶系，a=1.34656（15）nm，b=0.57356（6）nm，c=1.10977（12）nm，β=100.636（2）°，V=0.84239（46）nm^3，空间群P21/a（假C2/m），Z=2。作为硅钛铈矿（chevkinite）族矿物的新成员，它产于举世闻名的白云鄂博铁-稀土-铌矿床镁夕卡岩中，多数单晶体长0.2-1.0 cm，最大者长大于1.5 cm。共生矿物有透辉石、透闪石、钠透闪石、褐帘石-（Ce）、磁铁矿、尖晶石、烧绿石、氟金云母、氟磷灰石、石英和萤石等。矿物具有褐色条痕和半金属-金属光泽的黑色，其褐黑色碎片半透明。性脆、具有贝壳状断口、无解理和裂开。显微硬度（VHN25g）为606.0-717.4 kg/mm^2（相当于摩氏硬度约5.9）。矿物实测密度4.83（7）g/cm^3，计算密度值4.88（0）g/cm^3。丁道衡矿-（Ce）的反射色为带灰色的浅黄色，多色性为不同色调的灰色。平均反射率（λ=589nm）为11.4%-12.5%。矿物为二轴晶负光性。作过结构精测的丁道衡矿-（Ce）晶体的电子探针测值：SiO2：19.29，TiO2：18.26，A l2O3：0.04，FeO：8.49，Fe2O3：1.67，ThO2：0.16，MgO：1.32，CaO：2.17，Nb2O5：0.47，Ta2O5：0.00，La2O3：19.53，Ce2O3：28.08，Y2O3：0.00，Na2O：0.01，总量99.46%；其中Fe^3＋/Fe^2＋的比值依穆斯堡尔谱换算。根据结构精测每个单位分子式中O=22和C（1）位上Ti优先占位，计算的矿物晶体化学式为（Ce2.13La1.49Ca0.48Th0.01）Σ4.11Fe2＋（Ti0.88Fe02.＋47Mg0.41Fe03.2＋6A l0.01）Σ2.03（Ti1.96Nb0.04）Σ2.00（Si2O7）2O8。分别用P21/a和C2/m对丁道衡矿-（Ce）的晶体结构作了精测。结果表明，丁道衡矿-（Ce）的真空间群是P21/a。换言之，它才是真正珀硅钛铈矿[perrierite-（Ce）]的同质多象体。显而易见，硅钛铈矿族矿物既可以有P21/a空间群，又可以有C2/m空间群。

Sensors Grouping Model for Wireless Sensor Network

The grouping of sensors is a calculation method for partitioning the wireless sensor network into groups, each group consisting of a collection of sensors. A sensor can be an element of multiple groups. In the present paper, we will show a model to divide the wireless sensor network sensors into groups. These groups could communicate and work together in a cooperative way in order to save the time of routing and energy of WSN. In addition, we will present a way to show how to organize the sensors in groups and provide a combinatorial analysis of some issues related to the performance of the network.

Constraints on unconsolidated pyroclastic flow sediments related REE enrichments originated from potassic-alkaline Gölcük stratovolcano: Darıdere-Direkli-Yakaören (DDY) table 4deposits, southwestern Anatolia of Turkey

In the last five decades,Rare Earth Elements(REE)are mostly produced from carbonatite complexes and alkaline magmatic environments.In this respect,pyroclastic flows produced by the potassic-alkaline Gölcük volcanism in the Isparta(SW,Turkey)angle stand out as an important target area where REE enrichments can be observed.This study focuses on the REE potential,geochemical and mineralogical characteristics of REE-bearing minerals as well as formation modeling of unconsolidated pyroclastic flows in Darıdere-Direkli-Yakaören(DDY)deposits in Turkey.REE-bearing minerals of DDY deposits which contain abundant trachytic-trachyandesitic rock fragments were determined as fluorapatite,britholite,and chevkinite by using XRD and SEM–EDX analyses.According to the geochemical analysis,the vast majority of RREE(up to 996 ppm)content is LREE such as La,Ce and Nd.Darıdere is the most REE enriched region followed by Yakaören and Direkli regions in terms of LREE(574.9 ppm),relative to MREE(38.5 ppm)and HREE(5.28 ppm)contents.These results are also on par with subduction-related Italian extrusive carbonatites such as Polino,Cupaello and San Venenzo.The DDY deposits can also be comparable with intraplate extrusive REE deposits in terms of LREE enrichments,however,HREE,Nb,Th and Zr values are generally lower.The RREE concentrations tend to rise with the increasing contents of alkaline elements(Na and K),HFSE(such as Nb and U),as well as LILE(Ba,Sr and Rb)and are negatively affected by sedimentary carbonate involvement.The economic value of the DDY deposits can gain importance due to the increasing global demand for LREE’s.

A Generalization of Cuccia＇s Theorem

For a finite group G, let S（G） be the set of minimal subgroups of odd order,which are complemented in G. It is proved that if every minimal subgroup X of odd orderof G which does not belong to S（G）, CG（X） is either subnormal or abnormal in G. Then Gsolvable.

Morphological Diversity and Nomenclature of Swertia chirayita (Gentianaceae)—Recovery of Endangered Medicinal Plant Population in North Eastern Himalaya

Swertia chirayita is a highly endangered and very well known medicinal plant enlisted in the IUCN list of endangered plants in the world. The plant is currently having a very low population in eastern Himalayan region due to its very low germinability in its own natural habitat. The plant population was found to have a range of diversity in morphological observations and some of the morphovariants were found to be very low among the variant populations which created a concern due to its diminishing range of genetic base in this region. A basic group of 5 morphovariants and 24 sub variants were identified and separately maintained. It is a pluriannual plant and reproductive or flowering stage was observed after completion of two years of vegetative stage from the time of seed germination. A range of morphovariant diversity was observed in the populations of Neora Valley and Lava region of eastern Himalaya in our investigation. Diversity was critically observed in some of the parameters of different morphovariants in the population. Conservation practices were generally done by not making groups or sub groups of this endangered plant while we proposed the way of conservation by making groups for proper conservation of this vulnerable plant.

Observation-Oriented Causal Discovery for Cultivation Abandonment of Rice Terraces: Focusing on an Effect of Cultural Endemism on Decision-Making in Toraja, Indonesia

Previous discussion about the factors of the expanding trend of abandoned cultivation had focused only on universal factors and lacked evaluation of the regionality of the phenomenon. This paper demonstrated the Toraja’s regional characteristics and the influence of cultural endemism on decision-making about abandoning cultivation by an observation-oriented approach. Based on a causal framework constructed by field observation and geospatial data generation, an adjustment for overt covariates using the multivariate logistic regression model to draw the causal effect from hidden covariates was examined in two rice terraces with different water systems, i.e. irrigated field and rain-fed field. The result of sub-group analysis revealed that decisions about abandoning cultivation in Toraja were greatly associated with disadvantageous factors for intensive farming, i.e. “number of adjacent fields” and “soil erosion” rather than advantageous factors, i.e. “area of field” and “distance to roads”. Moreover, the result of interaction analysis which controlled the effect of topography revealed the powerful effect of particular decision factors only in rain-fed rice terrace: the “distance to roads” factor’s fairly negative contribution on abandoning cultivation (Odds ratio = 9.94E - 01, P value = 2.03E - 11), as well as the “number of adjacent field” factor’s positive contribution on abandoning cultivation (Odds ratio = 1.13E+00, P value = 3.65E - 04). Given the evidence from the explanation of these results by customary laws and land inheritance system for each site, therefore, it could be concluded that the screening and detection of cultural endemism’s influence was achieved using the algorithm this paper proposes.

Analysis of the Effect of Subgroup Size on the X-Bar Control Chart Using Forensic Science Laboratory Sample Influx Data

This paper analyzes the effect of subgroup size on the x-bar chart characteristics using sample influx (SIF) into forensic science laboratory (FSL). The characteristics studied include changes in out-or-control points (OCP), upper control limit UCLx, and zonal demarcations. Multi-rules were used to identify the number of out-of-control-points, Nocp as violations using five control chart rules applied separately. A sensitivity analysis on the Nocp was applied for subgroup size, k, and number of sigma above the mean value to determine the upper control limit, UCLx. A computer code was implemented using a FORTRAN code to create x-bar control-charts and capture OCP and other control-chart characteristics with increasing k from 2 to 25. For each value of k, a complete series of average values, Q(p), of specific length, Nsg, was created from which statistical analysis was conducted and compared to the original SIF data, S(t). The variation of number of out-of-control points or violations, Nocp, for different control-charts rules with increasing k was determined to follow a decaying exponential function, Nocp = Ae–α, for which, the goodness of fit was established, and the R2 value approached unity for Rule #4 and #5 only. The goodness of fit was established to be the new criteria for rational subgroup-size range, for Rules #5 and #4 only, which involve a count of 6 consecutive points decreasing and 8 consecutive points above the selected control limit (σ/3 above the grand mean), respectively. Using this criterion, the rational subgroup range was established to be 4 ≤ k ≤ 20 for the two x-bar control chart rules.

福建漳平(永福)方言的一种比较句——一次难忘的方言语法调查经历

笔者从1978年开始系统调查福建漳平(永福)方言,一直到1992年出版《漳平方言研究》,前后断断续续历经14个年头。漳平永福是闽西南的一个高山乡镇,所说方言属于闽南话,但受到客家话的强烈影响。当地人与厦门一带的人交往,需要有一段适应时间,才能顺利通话。

On Nearly SS-Embedded Subgroups of Finite Groups

Abstract Let H be a subgroup of a finite group G. H is nearly SS-embedded in G if there exists an S-quasinormal subgroup K of G, such that HK is S-quasinormal in G and H∩ K≤HseG, where HseG is the subgroup of H, generated by all those subgroups of H which are S-quasinormally embedded in G. In this paper, the authors investigate the influence of nearly SS-embedded subgroups on the structure of finite groups.

Hydrogen Bond Cooperative Effect in Single Cage Water Clusters

In this paper,DFT method was used to study the relative stability of hydrogen bonding networks of numerous 512,51262 and 435663 water cluster isomers.Herein we introduced an optimized six-digit definition to characterize diverse sub-grouped hydrogen bonds to consider the cooperative effect of the nearest and nextnearest neighbor water molecules.There are totally 74 kinds of sub-grouped hydrogen bonds in cage hydrate clusters,and these energies can be obtained by iterative calculations.This improvement effectively explains some regularity contained in hydrogen bonding cooperative effect.In general,donor or acceptor fragment sharing identical value of three independent digits usually performs poor cooperative effect,indicating that the existence of those same-digital-array fragments is the necessary condition to judge poor cooperative effect.Vice versa,the existence of different-digital-array is also the necessary condition to judge strong cooperative effect.

The group theory for solving electromagnetic scattering problems with geometric symmetric structure

It is a very important issue to reduce computer storage and calculation time for matrix in solving scattering field by making use of geometric and physical symmetric features of a scattering body. A general definition for the symmetric and anti-symmetric structure is given by applying the group theory in mathematics and a general method for treating the electromagnetic scattering problems with symmetry is proposed. An example for applying the theory mentioned above is also given.

On Local Nilpotency of the Normal Subgroups of a Group

A group G is said to have property μ whenever N is a non-locally nitpotent normal subgroup of G, there is a finite non-nilpotent G-quotient of N. FC-groups and groups with property v satisfy property μ, where a group G is said to have property v if every non-nilpotent normal subgroup of G has a finite non-nilpotent G-quotient. HP（G） is the Hirsch-Plotkin radical of G, and φf （G） is the intersection of all the maximal subgroups of finite index in G （here φf（G） = G if no such maximal subgroups exist）. It is shown that a group G has property μ if and only if HP（G/φf（G）） = HP（G）/φf（G） and that the class of groups with property v is a proper subclass of that of groups with property it. Also, the structure of the normal subgroups of a group： nilpotency with the minimal condition, is investigated.