| 1. |
- Clark, Andrew G., et al.
(författare)
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Evolution of genes and genomes on the Drosophila phylogeny
- 2007
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 450:7167, s. 203-218
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Tidskriftsartikel (refereegranskat)abstract
- Comparative analysis of multiple genomes in a phylogenetic framework dramatically improves the precision and sensitivity of evolutionary inference, producing more robust results than single-genome analyses can provide. The genomes of 12 Drosophila species, ten of which are presented here for the first time (sechellia, simulans, yakuba, erecta, ananassae, persimilis, willistoni, mojavensis, virilis and grimshawi), illustrate how rates and patterns of sequence divergence across taxa can illuminate evolutionary processes on a genomic scale. These genome sequences augment the formidable genetic tools that have made Drosophila melanogaster a pre-eminent model for animal genetics, and will further catalyse fundamental research on mechanisms of development, cell biology, genetics, disease, neurobiology, behaviour, physiology and evolution. Despite remarkable similarities among these Drosophila species, we identified many putatively non-neutral changes in protein-coding genes, non-coding RNA genes, and cis-regulatory regions. These may prove to underlie differences in the ecology and behaviour of these diverse species.
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| 2. |
- Khalizov, Alexei F., et al.
(författare)
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Formation of highly hygroscopic soot aerosols upon internal mixing with sulfuric acid vapor
- 2009
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Ingår i: Journal of Geophysical Research. - 2156-2202. ; 114
-
Tidskriftsartikel (refereegranskat)abstract
- The hygroscopic properties of submicron soot particles during internal mixing with gaseous sulfuric acid have been investigated using a combined tandem differential mobility analyzer (TDMA) and differential mobility analyzer-aerosol particle mass analyzer (DMA-APM) technique. Fresh particles exhibit no change in mobility size and mass at subsaturated conditions, whereas particles exposed to gaseous sulfuric acid (10(9)-10(10) molecule cm(-3), 12 s contact time) experience significant mobility size and mass changes with increasing relative humidity (RH). The DMA-APM measurements reveal that particles of all sizes exposed to H2SO4 vapor gain mass with increasing RH because of absorption of water by sulfuric acid coating. However, on the basis of mobility size measurements using TDMA, upon humidification H2SO4-coated soot agglomerates display distinct hygroscopic growth patterns depending on their initial size and the mass fraction of condensed sulfuric acid. While small particles experience an increase in their mobility sizes, larger particles exhibit a marked shrinkage due to compaction. We suggest that determination of the hygroscopic properties of soot particles using a TDMA alone can be inconclusive. Restructuring of the soot agglomerates and filling of the voids that accompany the condensation of water-soluble materials and subsequent water absorption lead to little or no observable changes in particle mobility size at subsaturated RH even for particles that contain aqueous coatings. Extrapolation of our experimental results to the urban atmosphere indicates that initially hydrophobic soot particles acquire sufficient sulfate coating to become efficient CCN (cloud condensation nuclei) within a time period ranging from a few hours to a few days, dependent on the ambient H2SO4 level. The results imply that internal mixing with sulfuric acid through H2SO4 vapor condensation likely represents a common aging process for a variety of atmospheric aerosols. The variations in the size and hygroscopicity of soot particles during atmospheric processing influence their optical properties, cloud-forming potential, and human health effects.
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| 3. |
- Richards, Stephen, et al.
(författare)
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The genome of the model beetle and pest Tribolium castaneum.
- 2008
-
Ingår i: Nature. - 1476-4687. ; 452:7190, s. 949-55
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Tidskriftsartikel (refereegranskat)abstract
- Tribolium castaneum is a representative of earth’s most numerous eukaryotic order, a powerful model organism for the study of generalized insect development, and also an important pest of stored agricultural products. We describe its genome sequence here. This omnivorous beetle has evolved an ability to interact with a diverse chemical environment as evidenced by large expansions in odorant and gustatory receptors, as well as p450 and other detoxification enzymes. Developmental patterns in Tribolium are more representative of other arthropods than those found in Drosophila, a fact represented in gene content and function. For one, Tribolium has retained more ancestral genes involved in cell-cell communication than Drosophila, and some are expressed in the growth zone crucial for axial elongation in short germ development. Systemic RNAi in T. castaneum appears to use mechanisms distinct from those found in C. elegans, but nevertheless offers similar power for the elucidation of gene function and identification of targets for selective insect control.
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| 4. |
- Sodergren, Erica, et al.
(författare)
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The genome of the sea urchin Strongylocentrotus purpuratus.
- 2006
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 314:5801, s. 941-52
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Tidskriftsartikel (refereegranskat)abstract
- We report the sequence and analysis of the 814-megabase genome of the sea urchin Strongylocentrotus purpuratus, a model for developmental and systems biology. The sequencing strategy combined whole-genome shotgun and bacterial artificial chromosome (BAC) sequences. This use of BAC clones, aided by a pooling strategy, overcame difficulties associated with high heterozygosity of the genome. The genome encodes about 23,300 genes, including many previously thought to be vertebrate innovations or known only outside the deuterostomes. This echinoderm genome provides an evolutionary outgroup for the chordates and yields insights into the evolution of deuterostomes.
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| 5. |
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| 6. |
- Aktas, A., et al.
(författare)
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Measurement of event shape variables in deep-inelastic scattering at HERA
- 2006
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 46:2, s. 343-356
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Tidskriftsartikel (refereegranskat)abstract
- Deep-inelastic ep scattering data taken with the H1 detector at HERA and corresponding to an integrated luminosity of 106 pb(-1) are used to study the differential distributions of event shape variables. These include thrust, jet broadening, jet mass and the C-parameter. The four-momentum transfer Q is taken to be the relevant energy scale and ranges between 14 GeV and 200 GeV. The event shape distributions are compared with perturbative QCD predictions, which include resummed contributions and analytical power law corrections, the latter accounting for non-perturbative hadronisation effects. The data clearly exhibit the running of the strong coupling alpha(s)(Q) and are consistent with a universal power correction parameter alpha(0) for all event shape variables. A combined QCD fit using all event shape variables yields alpha(s)(m(Z)) = 0.1198 +/- 0.0013 (+0.0056)(-0.0043) and alpha(0) = 0.476 +/- 0.008 (+0.018)(-0.059).
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| 7. |
- Elsik, Christine G., et al.
(författare)
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The Genome Sequence of Taurine Cattle : A Window to Ruminant Biology and Evolution
- 2009
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 324:5926, s. 522-528
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Tidskriftsartikel (refereegranskat)abstract
- To understand the biology and evolution of ruminants, the cattle genome was sequenced to about sevenfold coverage. The cattle genome contains a minimum of 22,000 genes, with a core set of 14,345 orthologs shared among seven mammalian species of which 1217 are absent or undetected in noneutherian (marsupial or monotreme) genomes. Cattle-specific evolutionary breakpoint regions in chromosomes have a higher density of segmental duplications, enrichment of repetitive elements, and species-specific variations in genes associated with lactation and immune responsiveness. Genes involved in metabolism are generally highly conserved, although five metabolic genes are deleted or extensively diverged from their human orthologs. The cattle genome sequence thus provides a resource for understanding mammalian evolution and accelerating livestock genetic improvement for milk and meat production.
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| 8. |
- Hedlin, Dan, 1960-, et al.
(författare)
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Future challenges of small area estimation
- 2006
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Ingår i: Statistics in transition. - Warsaw : Polish Statistical Association. - 1234-7655. ; 7:4, s. 759-769
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Tidskriftsartikel (refereegranskat)abstract
- A panel discussion session entitled as “Future Challenges of Small Area Estimation” was organized in the SAE2005 Conference, with Ray Chambers as the organizer and chair and Jan van den Brakel, Dan Hedlin, Marie Cruddas, Risto Lehtonen, Imbi Traat and Li-Chun Zhang as the discussants. The output of the panel discussion session is summarized in this paper. Each contributor is responsible of the respective piece of text; the paper has been edited by the chairman of the session.
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| 9. |
- Holland, Linda Z, et al.
(författare)
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The amphioxus genome illuminates vertebrate origins and cephalochordate biology
- 2008
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Ingår i: Genome Research. - : Cold Spring Harbor Laboratory. - 1088-9051 .- 1549-5469. ; 18:7, s. 1100-1111
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Tidskriftsartikel (refereegranskat)abstract
- Cephalochordates, urochordates, and vertebrates evolved from a common ancestor over 520 million years ago. To improve our understanding of chordate evolution and the origin of vertebrates, we intensively searched for particular genes, gene families, and conserved noncoding elements in the sequenced genome of the cephalochordate Branchiostoma floridae, commonly called amphioxus or lancelets. Special attention was given to homeobox genes, opsin genes, genes involved in neural crest development, nuclear receptor genes, genes encoding components of the endocrine and immune systems, and conserved cis-regulatory enhancers. The amphioxus genome contains a basic set of chordate genes involved in development and cell signaling, including a fifteenth Hox gene. This set includes many genes that were co-opted in vertebrates for new roles in neural crest development and adaptive immunity. However, where amphioxus has a single gene, vertebrates often have two, three, or four paralogs derived from two whole-genome duplication events. In addition, several transcriptional enhancers are conserved between amphioxus and vertebrates--a very wide phylogenetic distance. In contrast, urochordate genomes have lost many genes, including a diversity of homeobox families and genes involved in steroid hormone function. The amphioxus genome also exhibits derived features, including duplications of opsins and genes proposed to function in innate immunity and endocrine systems. Our results indicate that the amphioxus genome is elemental to an understanding of the biology and evolution of nonchordate deuterostomes, invertebrate chordates, and vertebrates.
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| 10. |
- Li, Xuemei, et al.
(författare)
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Perfluorooctanesulfonate and related fluorochemicals in the Amur tiger (Panthera tigris altaica) from China
- 2008
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 42:19, s. 7078-7083
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Tidskriftsartikel (refereegranskat)abstract
- Perfluorinated compounds (PFCs) are used in a variety of industrial applications. We tested the hypothesis that, in Amur tigers (Panthera tigris altaica), captivity in industrialized areas increases PFC levels, potentially presenting a health risk to these animals. Serum samples were collected from 100 tigers from industrialized or nonindustrialized regions in China with nonpoint sources of PFCs. Mean concentrations of PFCs in these samples ranged from 1.57 ± 0.83 ng/mL in nonindustrial Hailin to 4.31 ± 2.90 ng/mL in industrial Beijing. PFC concentrations were significantly higher in tigers from the industrial city of Harbin than those from Hailin (p < 0.05). Perfluorooctanesulfonate (PFOS) was the most abundant PFC in all tigers and increased with age, regardless of industrial/nonindustrial background (p < 0.01). However, PFOS concentrations were 2-4 orders of magnitude less than the current no-observed-effect level. In addition, overall PFC levels in Amur tigers were low compared with various species living in other countries, consistent with the relatively short history of PFC use in China. These results are consistent with the hypothesis that captivity in industrialized areas increases PFC levels in Amurtigers. They also suggestthat PFC accumulation will persist, and even increase, with continued use of PFCs in China.
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| 11. |
- Norbäck, Dan, et al.
(författare)
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Asthma, eczema, and reports on pollen and cat allergy among pupils in Shanxi province, China
- 2007
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Ingår i: International Archives of Occupational and Environmental Health. - : Springer Science and Business Media LLC. - 0340-0131 .- 1432-1246. ; 80:3, s. 207-216
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To study self-reported asthma, eczema, and pollen and furry pet allergy among pupils (9-20 years) in Shanxi province, China, in relation to dietary and environmental factors. METHODS: A standardised questionnaire was distributed to pupils in two primary and two secondary schools, one in Taiyuan city (3.0 milj. inhabitants), the others in Qingxu county, a rural area 30 km outside Taiyuan. Totally, 2,116 pupils (90%) participated. RESULTS: Fifty percent were girls, 61% had been growing up on the countryside, 18% lived in Taiyuan now, 1.7% had ever had asthma, 0.8% had doctor's diagnosed asthma, 1.4% pollen allergy, 1.7% cat allergy, and 0% had dog allergy. Multiple logistic regression was applied, controlling for age, gender, diet, indoor exposures, rural childhood, and current urban residency. Girls had less eczema (OR = 0.51; 95%CI 0.28-0.92). Pupils in the city had more eczema (OR = 5.05; 95% CI 1.11-23.3). Those with a rural childhood had less asthma (OR = 0.17; 95% CI 0.05-0.60), eczema (OR = 0.15; 95% CI 0.13-0.66) and pollen/cat allergy (OR = 0.50; 95%CI 0.25-0.99). None of the indoor variables was related to asthma or allergy. Children with frequent fruit consumption had less asthma (OR = 0.40; 95% CI 0.19-0.82) and pollen/cat allergy (OR = 0.49; 95% CI 0.29-0.84). Those with frequent fish consumption had less asthma (OR = 0.32; 95% CI 0.11-0.97). Those with frequent hamburgers consumption had more asthma (OR = 2.05; 95% CI 1.09-3.87) and eczema (OR = 1.85; 95% CI 1.12-3.04). CONCLUSION: Asthma, eczema, and pollen or pet allergy was uncommon, compared with western countries and other areas in China. Pupils with a rural childhood had less asthma and allergy, which is consistent with the "hygiene hypothesis". Fruit and fish consumption may reduce, and fast food consumption may increase the risk for asthma. Finally, the higher prevalence of asthma and eczema among younger children, born in the 1990s, indicates a cohort effect similar to that observed in western countries.
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| 12. |
- Stjerndahl, Maria, 1975, et al.
(författare)
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NMR studies of aggregation and hydration of surfactants containing amide bonds
- 2007
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106. ; 111:8, s. 2008-2014
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Tidskriftsartikel (refereegranskat)abstract
- The consequences of including amide bonds into the structure of short-chain nonionic surfactants have been studied. Of particular interest were the possible effects of the hydrogen bonding ability of the amide group on the micellar shape. The aggregate structure and hydration of two different amide-containing surfactants, C7H15CO-NH-(CH2CH2O)(4)H and C7H15CO-(NH-C3H6-CO)(2)N(CH3)(2), were investigated using NMR diffusometry (pulsed gradient spin echo NMR) as the main technique. Data from experiments on the surfactants, the hydrophobic probe molecule hexamethyldisilane (HMDS), and water were interpreted to gain information about the solution structures, and the results were compared to those on a previously studied alcohol ethoxylate surfactant of similar size, C8E4. Both of the amide-containing surfactants form small micelles within the whole investigated concentration range. At the critical micelle concentration, the aggregates are most probably spherical, and with increasing surfactant concentration there are indications of either a minor aggregate growth or agglomeration of the micelles. In addition, it was found that the presence of amide groups in the surfactant inhibits the intermicellar transport of HMDS, which occurs in the C8E4 system. From measurements on water diffusion in the three surfactant systems, it could be concluded that the surfactant hydration is higher when amide bonds are present.
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| 13. |
- Wang, Lihui, et al.
(författare)
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A parallel robotic attachment and its remote manipulation
- 2006
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Ingår i: Robotics and Computer-Integrated Manufacturing. - : Elsevier. - 0736-5845 .- 1879-2537. ; 22:5-6, s. 515-525
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Tidskriftsartikel (refereegranskat)abstract
- This paper discusses a 3-dof (degree of freedom) parallel robotic attachment and its remote manipulation. This attachment is designed as a tripod that provides two rotary motions and one linear motion. The attachment can be mounted onto a variety of machines for different applications, including CNC milling machines, industrial robots, and CMM. Java technologies are used to develop a remote manipulation system for the parallel robotic attachment, including remote monitoring and control. The main difference of this system from the existing web-based or internet-based remote systems is the way to control the motion of the machine from a remote site. Instead of using a camera for monitoring, the tripod is modeled using 3D computer graphics with behavioral control nodes embedded.Compared with camera-based solutions, network traffic is largely reduced, thereby making real-time remote device manipulation practical on the web. Our parallel robotic attachment is one type of parallel kinematic mechanisms (PKM). With PKM emerging as a new way of building flexible systems or agile machines, its advantage over serial mechanism is also presented.
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| 14. |
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| 15. |
- Wolever, Thomas M S, et al.
(författare)
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Measuring the glycemic index of foods: interlaboratory study.
- 2008
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Ingår i: The American journal of clinical nutrition. - 0002-9165 .- 1938-3207. ; 87:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Many laboratories offer glycemic index (GI) services. OBJECTIVE: We assessed the performance of the method used to measure GI. DESIGN: The GI of cheese-puffs and fruit-leather (centrally provided) was measured in 28 laboratories (n=311 subjects) by using the FAO/WHO method. The laboratories reported the results of their calculations and sent the raw data for recalculation centrally. RESULTS: Values for the incremental area under the curve (AUC) reported by 54% of the laboratories differed from central calculations. Because of this and other differences in data analysis, 19% of reported food GI values differed by >5 units from those calculated centrally. GI values in individual subjects were unrelated to age, sex, ethnicity, body mass index, or AUC but were negatively related to within-individual variation (P=0.033) expressed as the CV of the AUC for repeated reference food tests (refCV). The between-laboratory GI values (mean+/-SD) for cheese-puffs and fruit-leather were 74.3+/-10.5 and 33.2+/-7.2, respectively. The mean laboratory GI was related to refCV (P=0.003) and the type of restrictions on alcohol consumption before the test (P=0.006, r2=0.509 for model). The within-laboratory SD of GI was related to refCV (P<0.001), the glucose analysis method (P=0.010), whether glucose measures were duplicated (P=0.008), and restrictions on dinner the night before (P=0.013, r2=0.810 for model). CONCLUSIONS: The between-laboratory SD of the GI values is approximately 9. Standardized data analysis and low within-subject variation (refCV<30%) are required for accuracy. The results suggest that common misconceptions exist about which factors do and do not need to be controlled to improve precision. Controlled studies and cost-benefit analyses are needed to optimize GI methodology. The trial was registered at clinicaltrials.gov as NCT00260858.
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| 16. |
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| 17. |
- Zhang, Dan, et al.
(författare)
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Conceptual Development of an Enhanced Tripod Mechanism for Machine Tool
- 2005
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Ingår i: Robotics and Computer-Integrated Manufacturing. - : Elsevier. - 0736-5845 .- 1879-2537. ; 21:4-5, s. 318-327
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a spatial three degrees of freedom parallel mechanism enhanced by a passive leg is proposed. The proposed parallel mechanism can be used in several applications, e.g. motion simulator, micromanipulator and machine tools. First, the geometric model of the three degrees of freedom parallel mechanism is addressed, in which a fourth kinematic link—a passive link connecting the base center to the platform center—is introduced. This last link is used to constrain the motion of the platform to only three degrees of freedom, i.e. the degree of freedom of the mechanism depends on the passive leg. The passive leg also enhances the global stiffness of the structure and distributes the torque from machining. Second, the kinematic analysis with the consideration of link flexibility is conducted. A kinetostatic model of the three degrees of freedom parallel mechanism with a passive link is then established and analyzed using lumped-parameter model. With the proposed method, a significant effect of the link flexibility on the mechanism's precision has been demonstrated. The influence of the change of structure parameters, including material properties, on the system behavior is discussed. Compliance mapping is also illustrated. The kinetostatic model proposed in the paper can be extended for optimal design and control of parallel kinematic machines. Finally, design optimization is conducted using genetic algorithms and some design guideline is given.
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| 18. |
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| 19. |
- Zhang, Dan, et al.
(författare)
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Kinematic, Dynamic Modeling and Remote Control of a Robotic Machine
- 2007
-
Ingår i: 2007 IEEE International Conference on Control and Automation, ICCA. - : IEEE. - 9781424408177
-
Konferensbidrag (refereegranskat)abstract
- In this paper, a robotic machine with 3 degrees of freedom (DOF) is proposed. First, the geometric structure of the 3-DOF parallel robot is presented; in the mechanism, a fourth kinematic link -a passive link connecting the base center to the moving platform center -is introduced. This last link is used to constrain the motion of the moving platform to only 3-DOF. Then, the kinematic and dynamic models are developed. With the models, a web-based remote control approach is then applied. The 3-DOF parallel robot can be used as a machine tool for the purpose of polishing, deburring and milling, etc. Finally, an experiment to demonstrate the proposed 3-DOF structure is set up, and some conclusions are given by the end.
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| 20. |
- Zhang, Dan, et al.
(författare)
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On Performance Enhancement of Parallel Kinematic Machine
- 2005
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Ingår i: Proceedings of the ASME International Design Engineering Technical Conferences and Computers and Information in Engineering Conference - DETC2005. - : ASME Press. - 079184739X ; , s. 123-129
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Konferensbidrag (refereegranskat)abstract
- This paper proposes a spatial three degrees of freedom parallel kinematic machine enhanced by a passive leg and a web-based remote control system. First, the geometric model of the three degrees of freedom parallel kinematic machine is addressed; in the mechanism, a fourth kinematic link — a passive link connecting the base center to the moving platform center — is introduced. This last link is used to constrain the motion of the tool (located in the moving platform) to only three degrees of freedom, as well as to enhance the global stiffness of the structure and distribute the torque from machining. With the kinematic model, a web-based remote control approach is then applied. The concept of the web-based remote manipulation approach is introduced and the principles behind the method are explored in detail. Finally, an example of remote manipulation is demonstrated to the proposed 3-DOF structure using web-based remote control concept before conclusions.
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| 21. |
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| 22. |
- Zhang, Dan, et al.
(författare)
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PKM Capabilities and Applications Exploration in a Collaborative Virtual Environment
- 2006
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Ingår i: Robotics and Computer-Integrated Manufacturing. - : Elsevier. - 0736-5845 .- 1879-2537. ; 22:4, s. 384-395
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Tidskriftsartikel (refereegranskat)abstract
- This paper introduces an integrated validation system that consists of the following modular components: kinematic/dynamic analysis module, kinetostatic model, CAD module, FEM module, CAM module, optimization module and virtual environment for remote control. In this paper, authors focus mainly on the modules of kinetostatic modeling, dynamic modeling, PKM design optimization and remote control realization. The prototype of a 3-dof Parallel Kinematic Machine (PKM) developed at the Integrated Manufacturing Technologies Institute of National Research Council of Canada (NRC-IMTI) is used as ail example throughout this paper.
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| 23. |
- Zhang, Dan, et al.
(författare)
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Web-Based Digital Shop Floor : Implementation of Business Service Management and Managerial Implications
- 2007
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Ingår i: International Journal of Internet and Enterprise Management. - 1476-1300 .- 1741-5330. ; 5:1, s. 78-90
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, a web-based collaborative framework called Wise-ShopFloor (Web-based integrated sensor-driven e-ShopFloor) is proposed. With appropriate open architecture for effective collaboration among a dispersed engineering team, the Wise-ShopFloor can serve real-time data from bottom up and can function as a constituent component of e-manufacturing for remote monitoring and control. This paper presents the basis of the framework for building web-based collaborative systems that can be used for distributed manufacturing. A proof-of-concept prototype system is developed on top of the framework to demonstrate one of its potential applications on shop floor monitoring and control.
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| 24. |
- Zhang, Dan, et al.
(författare)
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Web-Based Remote Manipulation in Advanced Manufacturing System
- 2005
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Ingår i: Proceedings of the IEEE EEE05 international workshop on Business services networks. ; , s. 105-111
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Konferensbidrag (refereegranskat)abstract
- In this paper, a Web-based collaborative framework is proposed. With appropriate open architecture for effective collaboration among a dispersed engineering team, the Web-based digital Shop Floor can serve real-time data from bottom up and can function as a constituent component of e-manufacturing for remote monitoring and control. This paper presents the basis of the framework for building web-based collaborative systems that can be used for distributed manufacturing. A proof-of-concept prototype system is developed on top of the framework to demonstrate one of its potential applications on shop floor monitoring and control.
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| 25. |
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| 26. |
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| 27. |
- Zhang, Xuanjun, et al.
(författare)
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Anion-Directed Assembly of Macrocycle and Helix
- 2006
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 6:6, s. 1440-1444
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Tidskriftsartikel (refereegranskat)abstract
- Self-assembly of the flexible ligand N,N‘-bis(3-pyridylmethyl)thiourea (bpt) with ZnCl2 and CdCl2 in the absence and presence of KSCN yielded a short series of novel complexes (1−4) with macrocyclic, helical, double-helical, and 1D polymeric structures. Different metal ions, hydrogen bonds, and counteranions play significant roles in the final crystal structures. The NCS- anion was found to favor the formation of helical structures, whereas the Cl- anion favored macrocycle formation in the present system. Photoluminescence (PL) measurement results revealed that complex 2 (Zn(bpt)(SCN)2) with a helical structure exhibits enhanced emissions compared to those of the ligand and other complexes. The anion-directed assembly as well as the interesting emissions may provide useful information for further design of metal−organic compounds with novel structures and properties.
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| 28. |
- Zhang, Xia, 1980, et al.
(författare)
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Design of 50-70 GHz Planar Wideband Bandpass Filter on Liquid Crystal Polymer Substrate
- 2009
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Ingår i: Journal of Infrared, Millimeter, and Terahertz Waves. - : Springer Science and Business Media LLC. - 1866-6892 .- 1866-6906. ; 30:2, s. 183-189
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the authors propose a novel and compact 50-70 GHz planar microstrip bandpass filter, possessing sharp-rejection, low insertion-loss and wide-band characteristics, based on Liquid Crystal Polymer (LCP) substrates. The filter is fabricated on LCP substrates by using standard processing technologies. The proposed filter exhibits a return loss level better than 10 dB, an insertion loss of 5 dB and a 3-dB bandwidth of 30%. The measured and simulated results show good agreement, proving that LCPs are potential and very promising materials for flexible millimeter-wave substrate applications.
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| 29. |
- Zhang, Xuanjun, et al.
(författare)
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Dichlorobis(phenothiazine-S)palladium(II)
- 2005
-
Ingår i: Acta Crystallographica Section E. - 1600-5368. ; E61, s. m603-m605
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Tidskriftsartikel (refereegranskat)abstract
- In the title complex, [PdCl2(C12H9NS)2], the Pd atom lies on a center of inversion and is coordinated by two chloride anions and two S atoms from two phenothiazine ligands, forming a square-planar PdCl2S2 geometry. In the crystal structure, a one-dimensional polymer structure is constructed via N-H...Cl and N-H...N hydrogen bonds.
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| 30. |
- Zhang, Xuanjun, et al.
(författare)
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From Large 3D Assembly to Highly Dispersed Spherical Assembly: Weak- and Strong- Coordination Mediated Self-Aggregation of Au Colloids
- 2006
-
Ingår i: New Journal of Chemistry. - : RSC Publishing. - 1144-0546 .- 1369-9261. ; 30, s. 706-711
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Tidskriftsartikel (refereegranskat)abstract
- Distinctly different 3D assemblies of 1.6 nm Au nanoparticles are constructed based on weak and strong coordination strategies. Reduction of KAuCl4 with NaBH4 in the presence of newly-synthesized 4-(4-phenylmethanethiol)-2,2′:6′,2′′-terpyridine (1) yields functionalized Au nanoparticles which assemble in situ into large 3D aggregates via weak coordination between alkali metal ions and terpyridine attached to separated particles. These assemblies are disassembled into individual nanoparticles via addition of DMF solvent and further reassembled into highly dispersed 3D spherical nanostructures via addition of Co2+ (strong coordination with 1). Wide and small angle XRD measurements show that the assemblies are formed from small Au nanoparticles, consistent with TEM results. It is significant that the large aggregates formed in situ can be directly transformed into nearly monodispersed 3D spherical assemblies via strong coordination (with Co2+), presenting the first example of a direct transformation of one 3D nanonetwork into another distinctly different 3D nanonetwork. The controlled assembly and disassembly processes are accompanied by distinct shifts in the surface plasmon resonance.
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| 31. |
- Zhang, Xuanjun, et al.
(författare)
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Metal-Compound-Induced Vesicles as Efficient Directors for Rapid Synthesis of Hollow Alloy Spheres†
- 2006
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Ingår i: Angewandte Chemie International Edition. - : Wiley-VCH Verlagsgesellschaft. - 1433-7851 .- 1521-3773. ; 45:36, s. 5971-5974
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Tidskriftsartikel (refereegranskat)abstract
- Hollow alloy: Vesicles formed from tetrabutylammonium bromide and metal compounds act as efficient directors for the rapid synthesis of a variety of binary, ternary, and quaternary intermetallic materials with hollow structures. In this way, different metals were co-alloyed on the vesicle surface to produce hollow alloy spheres containing more than two kinds of metals.
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| 32. |
- Zhao, Zhu, et al.
(författare)
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A comparative study of asthma, pollen, cat and dog allergy among pupils and allergen levels in schools in Taiyuan city, China, and Uppsala, Sweden
- 2006
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Ingår i: Indoor Air. - : Hindawi Limited. - 0905-6947 .- 1600-0668. ; 16:6, s. 404-413
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Tidskriftsartikel (refereegranskat)abstract
- We compared the school environment, asthma and allergy in 10 schools in Taiyuan, China, with eight schools in Uppsala, Sweden. In total 2193 pupils (mean age 13 years) participated. Chinese pupils had more respiratory symptoms, particularly daytime breathlessness after exercise (29.8% vs. 7.1%; P < 0.001), while cat allergy (1.2% vs. 6.6%; P < 0.001) and dog allergy (1.3% vs. 4.0%; P < 0.01) was less common. Cumulative incidence of asthma (1.8% vs. 9.5%; P < 0.001) and doctor's diagnosed asthma (1.2% vs. 9.0%; P < 0.001) were less common in China, indicating an under-diagnosis of asthma. Chinese classrooms were colder (mean 14.7 vs. 21.4 degrees C), more humid (mean 42% vs. 31% RH) and had higher CO2-levels (mean 2211 vs. 761 ppm). Levels of cat (Fel d1), dog (Can f1) allergens were low in settled dust from China (< 200 ng/g dust), but high in airborne dust on Petri-dishes (GM 16.8 ng/m2/day for Fel d1 and 17.7 for Can f1). The Swedish settled dust contained cat, dog and horse allergens in high levels (median 1300 ng/g, 1650 ng/g, 1250 U/g dust, respectively). In conclusion, there were large differences in the school environment, and in respiratory symptom and allergy. Allergen measurements in settled dust only may largely underestimate the classroom exposure. Practical Implications There is a need to improve the school environment, both in China and Sweden. The Swedish schools contained high levels of cat, dog and horse allergens and more amounts of open shelves and textiles that can accumulate dust and allergens. The air measurements indicated that Chinese schools may contain significant amounts of cat and dog allergen, and analysis of settled dust only may not reflect the true allergen exposure. Since the Chinese schools had no mechanical ventilation, they could not fulfill the ventilation standard in winter, and hence there is a need for improving the ventilation. The great discrepancy between respiratory symptoms and reports on asthma, and the high prevalence of attacks of breathlessness without wheeze, may have implication for future questionnaire studies on asthma in China.
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| 33. |
- Zhao, Zhuohui, et al.
(författare)
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Asthmatic symptoms among pupils in relation to microbial dust exposure in schools in Taiyuan, China
- 2008
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Ingår i: Pediatric Allergy and Immunology. - : Wiley. - 0905-6157 .- 1399-3038. ; 19:5, s. 455-465
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Tidskriftsartikel (refereegranskat)abstract
- Microbial exposure has been indicated as significant in the development of asthma and allergy among children. The aim of the study was to test whether microbial exposure and allergens in the school environment are associated with asthmatic symptoms in pupils. Data on asthmatic symptoms and respiratory infections were collected through a questionnaire survey among 1993 pupils aged 11-15 yr in 10 randomly selected schools in Taiyuan, China. Settled dust in classrooms was analysed using tandem gas chromatography-mass spectrometry for 3-hydroxy fatty acids, marker of lipopolysaccharide (LPS) from endotoxin, muramic acid (MuA), marker of bacteria and ergosterol (Erg) for fungi, quantifying both culturable and non-culturable microbes. A total of 29.8% reported daytime attacks of breathlessness, 8.4% wheeze and 1.2% had doctor's diagnosed asthma. Generally, MuA was negatively associated with wheeze and daytime attacks of breathlessness, the latter of which was negatively associated with Erg to a weaker extent. Total concentration of LPS was positively associated with daytime attacks of breathlessness, but shorter lengths of LPS, C10, C12 and C14 LPS were negatively associated with either wheezing or daytime attacks of breathlessness. For MuA and C10 and C12 of LPS, the associations were independent of airborne allergens and classroom crowdedness, and even independent of the other two microbial markers for MuA. Microbial exposure indicated by certain chemical markers (e.g. MuA) could be protective for asthmatic symptoms, but for LPS (endotoxin), the picture is more complex, varying by different lengths of fatty acids of LPS.
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| 34. |
- Zhao, Zhuohui, et al.
(författare)
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Asthmatic Symptoms among Pupils in Relation to Winter Indoor and Outdoor Air Pollution in Schools in Taiyuan, China
- 2008
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Ingår i: Journal of Environmental Health Perspectives. - : Environmental Health Perspectives. - 0091-6765 .- 1552-9924. ; 116:1, s. 90-97
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Tidskriftsartikel (refereegranskat)abstract
- Background: There are few studies on associations between children's respiratory heath and air pollution in schools in China. The industrial development and increased traffic may affect the indoor exposure to air pollutants in school environment. Moreover, there is a need to study respiratory effects of environmental tobacco smoke (ETS) and emissions from new building materials in homes in China. Objectives: We studied the associations between pupils' asthmatic symptoms and indoor and outdoor air pollution in schools, as well as selected home exposures, in a coal-burning city in north China. Methods: A questionnaire survey was administered to pupils (11–15 years of age) in 10 schools in urban Taiyuan, collecting data on respiratory health and selected home environmental factors. Indoor and outdoor school air pollutants and climate factors were measured in winter. Results: A total of 1,993 pupils (90.2%) participated ; 1.8% had cumulative asthma, 8.4% wheezing, 29.8% had daytime attacks of breathlessness. The indoor average concentrations of sulfur dioxide, nitrogen dioxide, ozone, and formaldehyde by class were 264.8, 39.4, 10.1, and 2.3 µg/m3, respectively. Outdoor levels were two to three times higher. Controlling for possible confounders, either wheeze or daytime or nocturnal attacks of breathlessness were positively associated with SO2, NO2, or formaldehyde. In addition, ETS and new furniture at home were risk factors for wheeze, daytime breathlessness, and respiratory infections. Conclusions: Indoor chemical air pollutants of mainly outdoor origin could be risk factors for pupils' respiratory symptoms at school, and home exposure to ETS and chemical emissions from new furniture could affect pupils' respiratory health.
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| 35. |
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| 36. |
- Zhou, Xiao-Ping, et al.
(författare)
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Anion-p-Interaction-Directed Self-Assembly of Ag(I) Coordination Networks
- 2007
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Ingår i: Crystal Growth & Design. - : American Chemical Society (ACS). - 1528-7483 .- 1528-7505. ; 7:3, s. 485-487
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Tidskriftsartikel (refereegranskat)abstract
- Reactions of AgX with 2,4,6-tri(2-pyridyl)-1,3,5-trazine (tpt) yielded three 3D highly symmetric isostructural coordination polymers (X = ClO4-, BF4-, and PF6-) and a dimer (X = CF3COO-), respectively. In the coordination polymers, anion−π interactions are found between the multiatomic anions and tpt ligands. Systematic variation including synthetic methods, ratios of reactants, and solvents provides synthetic evidence proving that anion−π interactions play a decisive role in assembly of the coordination polymers.
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| 37. |
- Zhou, Xiao-Ping, et al.
(författare)
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Cu(I) or Cu(I)-Cu(II) Mixed-Valence Complexes of 2,4,6-Tri(2-pyridyl)-1,3,5-triazine: Syntheses, Structures, and Theoretical Study of the Hydrolytic Reaction Mechanism
- 2006
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Ingår i: Inorganic Chemistry. - : American Chemical Society (ACS). - 0020-1669 .- 1520-510X. ; 45:18, s. 7119-7125
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Tidskriftsartikel (refereegranskat)abstract
- The reactions of 2,4,6-tri(2-pyridyl)-1,3,5-triazine (tpt) with copper(I) halides under solvothermal or traditional conditions yielded two polymeric Cu(I) complexes [Cu2I2(tpt)]n (1) and [Cu3I3(tpt)]n (2), one mixed-valence Cu(I)−Cu(II) complex [Cu4Cl2I4(tpt)2] (3), and two Cu(II) complexes [CuBr(bpca)] (4) and [CuI(bpca)] (5) (bpca = bis(2-pyridylcarbonyl)amine). Complex 1 is a zigzag chain with tpt in a bis-bipyridine-like coordination mode, whereas complex 2 with tpt chelating three Cu(I) cations is a ladderlike coordination polymer. Complex 3 is mixed-valence, with Cu(I) in a distorted tetrahedral geometry and Cu(II) in a distorted square pyramidal geometry, forming a ladderlike supramolecular chain. Complexes 4 and 5 are the products of in situ hydrolysis of tpt involving the oxidation of Cu(I). The synthesis and characterization of complex 1, 2, and 5 indicated that Cu(I) cannot promote the hydrolysis of tpt. The theoretical study shows that the main effect for hydrolysis of tpt is the electron-withdrawing effect of metal ions.
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| 38. |
- Zhou, Xiao-ping, et al.
(författare)
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Syntheses of supramolecular CuCN complexes by decomposing CuSCN: a general route to CuCN coordination polymers?
- 2006
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Ingår i: Dalton Transactions. - : RSC Publishing. - 1477-9226 .- 1477-9234. ; :20, s. 2435-2443
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Tidskriftsartikel (refereegranskat)abstract
- The solvothermal reaction of CuSCN with 1,2-bis(diphenylphosphino)ethane (dppe) yielded a coordination polymer, which was characterized to be a complex of CuCN and 1,2-bis(diphenylthiophosphinyl)ethane (dppeS2): [(CuCN)2(dppeS2)]n (1). The identification of complex 1 reveals that CuSCN was decomposed and the sulfur was transferred to dppe, and represents a new example of the transformation of inorganic sulfur to organic sulfur. The weak coordination interactions between CuCN and dppeS2 indicate that dppeS2 may be substituted by ligands with strong coordination ability. The ligand 2,4,6-tris(2-pyridyl)-1,3,5-triazine (tpt) was chosen as a substitute ligand. Three novel CuCN coordination polymers of tpt were synthesized and characterized: [Cu2(CN)2(tpt)]n (2) with a 3-D (10,3)-a network, [Cu2(CN)2(tpt)]n (3) and [Cu2(SCN)(CN)(tpt)]n (4) both with a 2-D (6,3) network, and only complex 2 can be obtained from CuCN directly. Interestingly, compounds 2 and 3 are genuine high-dimensional supramolecular isomers. During the syntheses of 2-4, single crystals of dppeS2 were isolated, which indicates it was substituted by tpt ligand and also confirmed the transformation of sulfur from CuSCN to dppe. The transformation of sulfur can be observed only when the temperature is relative high (>160 degrees C). At 140 degrees C, complex 5 containing only CuSCN was attained and no dppeS2 has been monitored in the resulting filtrate.
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