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Biomedical subjects

Chun Ye

Publications and source records attributed to Chun Ye.

18 recordsLinked to original sources
PubMed2006

Spectroscopic imaging ellipsometry: real-time measurement of single, intact wood pulp fibers.

A nondestructive method based on spectroscopic ellipsometry has been developed and demonstrated for the real-time measurement of a single pulp fiber's microfibril angle and phase retardation, with the latter proportional to the cell wall thickness. The method uses an optical arrangement insensitive to the sample's orientation in combination with a proper spectral analysis of the sample's image. The optical arrangement and the measurement principle of the method are described. To test the new method, equipment functioning as a spectroscopic imaging ellipsometer was constructed according to the arrangement, and measurements were carried out in which single pulp fibers and ordinary wave plates were measured. The test measurements and results are described and presented.

Algorithms↗
PubMed2006

Low-loss birefringent spectral filters comprising three identical retarders.

Basic fan or folded arrangements comprising three identical retarders in cascade between parallel or crossed polarizers are presented for constructing birefringent spectral filters without an internal polarizer. The retarders' axes are oriented with an angle increment of theta or -theta preferably with /theta/ <or=34.27 degrees such that their orientation angles are, respectively, equal to 45 degrees -theta, 45 degrees , and 45 degrees +theta for the fan arrangement, or 45 degrees +theta, 45 degrees +2theta, and 45 degrees +theta for the folded arrangement. A filter in the fan or folded arrangement has the bandwidth of its principal transmission peaks or the amplitude of the sidelobes adjustable by changing the angle increment /theta/. For /theta/ = 25.91 degrees, the filter exactly produces the transmission spectrum of a standard Lyot two-stage filter. Further, the filter can have the spectral transmission be electrically tunable or switchable, depending on the retarders selected for use. The retarders can be birefringent plates, liquid-crystal variable retarders, or liquid-crystal electrically rotatable retarders. Test measurements and results are presented and discussed.

Journal Article↗
PubMed2006

Low-loss tunable filter based on optical rotatory dispersion.

The optical arrangement of a spectral filter without an intermediate polarizer that was developed based on optical rotatory dispersion and test measurement results are presented and described. The filter uses three dispersive polarization rotators as the key elements in combination with two additional quarter-wave retarders, and it is wavelength tunable with a spectral transmission equivalent to that of a standard Lyot two-stage filter.

Journal Article↗
PubMed2005

Frustrated molecular packing in highly ordered smectic phase of side-chain liquid crystalline polymer with rigid polyacetylene backbone.

Using poly(5-{[(4'-heptoxy-4-biphenylyl)carbonyl]oxy}-1-pentyne) as an example, we demonstrate the incorporative accommodation of the rigid polyacetylene backbones and the mesogenic pendants, which leads to a highly ordered smectic (Sm) phase with a frustrated structure. The polymer exhibits a recognizable sheetlike molecular shape due to its rigid backbone and relatively short spacer (three methylene units), and the building block of the liquid crystalline (LC) phase is the whole molecule. In the LC phase, five layers of the molecules stack as a smectic A (SmA) block, and adjacent SmA blocks glide halfway of the molecular width from one to another. In scanning tunneling microscopy (STM) experiments, the STM tip scrape is found to generate a regular nanopattern with periodic electron conductivity, of which the spacing is determined by the side-chain length.

Journal Article↗
PubMed2005

Molecular evolution of growth hormone gene family in old world monkeys and hominoids.

Growth hormone is a classic molecule in the study of the molecular clock hypothesis as it exhibits a relatively constant rate of evolution in most mammalian orders except primates and artiodactyls, where dramatically enhanced rate of evolution (25-50-fold) has been reported. The rapid evolution of primate growth hormone occurred after the divergence of tarsiers and simians, but before the separation of old world monkeys (OWM) from new world monkeys (NWM). Interestingly, this event of rapid sequence evolution coincided with multiple duplications of the growth hormone gene, suggesting gene duplication as a possible cause of the accelerated sequence evolution. Here we determined 21 different GH-like sequences from four species of OWM and hominoids. Combining with published sequences from OWM and hominoids, our analysis demonstrates that multiple gene duplications and several gene conversion events both occurred in the evolutionary history of this gene family in OWM/hominoids. The episode of recent duplications of CSH-like genes in gibbon is accompanied with rapid sequence evolution likely resulting from relaxation of purifying selection. GHN genes in both hominoids and OWM are under strong purifying selection. In contrast, CSH genes in both lineages are probably not. GHV genes in OWM and hominoids evolved at different evolutionary rates and underwent different selective constraints. Our results disclosed the complex history of the primate growth hormone gene family and raised intriguing questions on the consequences of these evolutionary events.

Animals↗
PubMed2005

Liquid-crystalline phase development of a mesogen-jacketed polymer-application of two-dimensional infrared correlation analysis.

Two-dimensional correlation spectroscopy has been applied to study PMPCS (poly{2,5-bis[(4-methoxyphenyl)oxycarbonyl]styrene}), a representative example of mesogen-jacketed liquid crystalline polymers. With the precise analysis of a series of Fourier transform infrared (FTIR) spectra of PMPCS recorded at varied temperatures, a reasonable mechanism of the development of liquid crystalline (LC) phase is proposed. Before the phase transition, the conformational change of individual side chains occurs sooner than that of the backbone due to the larger motional freedom of the side chains. After the phase transition, however, the readjustment of still somewhat mobile backbone occurs before the ordered, rigid, and mutually interacting side chains. That is, phase transition leading to the LC phase formation brings in a new cooperative restriction of motions to the segments.

Journal Article↗
PubMed2005

Assessing computational tools for the discovery of transcription factor binding sites.

The prediction of regulatory elements is a problem where computational methods offer great hope. Over the past few years, numerous tools have become available for this task. The purpose of the current assessment is twofold: to provide some guidance to users regarding the accuracy of currently available tools in various settings, and to provide a benchmark of data sets for assessing future tools.

Amino Acid Motifs↗
PubMed2005

Orthologous repeats and mammalian phylogenetic inference.

Determining phylogenetic relationships between species is a difficult problem, and many phylogenetic relationships remain unresolved, even among eutherian mammals. Repetitive elements provide excellent markers for phylogenetic analysis, because their mode of evolution is predominantly homoplasy-free and unidirectional. Historically, phylogenetic studies using repetitive elements have relied on biological methods such as PCR analysis, and computational inference is limited to a few isolated repeats. Here, we present a novel computational method for inferring phylogenetic relationships from partial sequence data using orthologous repeats. We apply our method to reconstructing the phylogeny of 28 mammals, using more than 1000 orthologous repeats obtained from sequence data available from the NISC Comparative Sequencing Program. The resulting phylogeny has robust bootstrap numbers, and broadly matches results from previous studies which were obtained using entirely different data and methods. In addition, we shed light on some of the debatable aspects of the phylogeny. With rapid expansion of available partial sequence data, computational analysis of repetitive elements holds great promise for the future of phylogenetic inference.

Animals↗
PubMed2005

Independent origin of the growth hormone gene family in New World monkeys and Old World monkeys/hominoids.

The growth hormone (GH) gene family represents an erratic and complex evolutionary pattern, involving many evolutionary events, such as multiple gene duplications, positive selection, the birth-and-death process and gene conversions. In the present study, we cloned and sequenced GH-like genes from three species of New World monkeys (NWM). Phylogenetic analysis strongly suggest monophyly for NWM GH-like genes with respect to those of Old World monkeys (OWM) and hominoids, indicating that independent gene duplications have occurred in NWM GH-like genes. There are three main clusters of genes in putatively functional NWM GH-like genes, according to our gene tree. Comparison of the ratios of nonsynonymous and synonymous substitutions revealed that these three clusters of genes evolved under different kinds of selective pressures. Detailed analysis of the evolution of pseudogenes showed that the evolutionary pattern of this gene family in platyrrhines is in agreement with the so-called birth-and-death process.

Animals↗
PubMed2005

[Ecological restoration and reconstruction of degraded lakeside zone ecosystem].

As a kind of aquatic-terrestrial ecotone, lakeside zone plays an important role in the lake basin ecosystem, and has high ecological, social and economic values. Its functions include lake buffer, conservation of biological diversities and special habitats, dike protection from soil erosion, and economic and esthetics values. The main factors inducing lakeside zone degradation are the anthropogenic activities that caused the converse succession of communities and the decline of ecological function. The theoretical basis of ecological restoration and reconstruction of degraded lakeside zone is restoration ecology; while the technologies are of three types, i. e., habitat restoration and reconstruction, species restoration and reconstruction, and structural and functional restoration. A three-year case study on the ecosystem restoration and recontruction of degraded lakeside zone of Erhai Lake in Yunnan Province showed that the aquatic macrophytes were restored, purifying function was distinct, algae were restrained, and the component and individuals of zooplankton were changed. In a word, the biological diversity and stability in the degraded lakeside-zone ecosystem increased after the restoration and reconstruction.

Biodiversity↗
PubMed2004

Liquid-crystal bandpass filter based on the optical rotatory dispersion effect.

A bandpass spectral filter and the test measurement results are presented and described. The filter is developed and constructed by use of a ferroelectric liquid-crystal polarization rotator in combination with dispersive quartz optical rotators, and its wavelength selection is mechanically tunable and electrically switchable.

Journal Article↗
PubMed2004

[Detection and typing for swine leukocyte antigen].

Traditionally the cluster of swine leukocyte antigen (SLA) was typed by serological, cytological and biochemical methods. Many special molecular typing methods have been developed with the progress of molecular biological technology, such as PCR-RFLP, PCR-SSCP , MS and DNA sequencing. Here we discussed the advantages and disadvantages of each method based on the polymorphic and conservative (from the functional aspect, such as supertype and supermotif) characteristics of SLA, and illustrated the development of typing for SLA in the future. In addition, we pointed out the editorial mistakes about the serological haplotype of SLA in reference book and emphasized that the accurate polymorphism of SLA-DQB gene must be based on the cloning sequencing.

Animals↗
PubMed2003

Wavelength-tunable spectral filters based on the optical rotatory dispersion effect.

An optical arrangement for constructing wavelength-tunable spectral filters is presented that makes use of a set of dispersive polarization rotations to select wavelengths. A filter in the arrangement is initially mechanically tunable, requires no achromatic retarder, and can be further electrically tunable, switchable, or both, depending on the elements selected. Test measurements and results are presented and described. Modified arrangements with additional retarder(s) or liquid-crystal polarization rotator(s) are suggested and discussed.

Journal Article↗
PubMed2003

Manipulating supramolecular self-assembly via tailoring pendant group size of linear vinyl polymers.

In a series of poly[di(alkyl) vinylterephthalates] (PDAVTs) synthesized via radical polymerization, fine-tuning the size and shape of the side groups manipulated the supramolecular self-assembly and led to control over the formations between amorphous and 2D ordered hexagonal phases. To introduce the 2D long-range ordered structure, the size of the ester side groups at the 2- and 5-positions of the phenyl rings laterally attached to the backbones had to be in the range of propyl/isopropyl to hexyl. The relatively extended backbones observed in these polymers were attributed to steric effects from the side groups. When the n-alkyl groups were larger than hexyl, the ability to form the liquid crystalline phase gradually decreased. A completely disordered phase could be observed by substituting dodecyl groups as side groups.

Journal Article↗
PubMed2003

Clinical analysis of uncinate process carcinoma of the pancreas.

OBJECTIVE: To analyse the clinical features of uncinate process carcinoma of the pancreas and the diagnosis and treatment of this malignancy. METHOD: Fifty-nine patients with pancreas uncinate process carcinoma treated from January 1998 to September 2002 at our hospital were analysed retrospectively. RESULTS: Major symptoms of these patients were upper abdominal pain accompanied with lumbar pain, body weight loss and jaundice. Thirty-seven patients received regional pancreaticoduodenectomy (RP), 16 partial resection of the superior mesenteric vein-portal vein (SMV-PV) or superior mesenteric artery (SMA) and reconstruction, 1 anhydrous alcohol injection in the celiac nerve plexus, regional chemotherapy via a chemotherapy pump, and liver biopsy, and 5 no operation. The survival of the patients after operation was 2-46 months (median 12.1 months). Eleven patients are still alive with a longest survival of 46 months. The 1- and 3-year survival rates were 37.7% and 5.6%. CONCLUSIONS: Pancreas uncinate process carcinoma invading the adjacent SMV/SMA-PV causes difficulty in early diagnosis and poor prognosis, which are related to its location, not tumor's aggressive nature. This carcinoma has a high resection rate of 89.8%.

Aged↗
PubMed2003

[Cloning of novel pituitary growth hormone gene from Rhinopithecus roxellanae].

Putative pituitary growth hormone gene of Rhinopithecus roxellanae was cloned and sequenced. All exons sequences and deduced amino acid sequence (containing 26 residues signal peptide and 191 residues mature protein) were obtained. We constructed a phylogenetic tree,which well reflected the true evolutionary relationship of pituitary growth hormone genes from 7 primates species. From the results of amino acids sequence comparison and analysis of functionally important sites of growth hormone, pituitary growth hormone of macaque from Cercopithecidae and snub-nosed golden monkey from Colobidae show little difference. We indicated that pituitary growth hormone from Cercopithecoidea species have no apparently functional difference.

English Abstract↗
PubMed2002

[Uncinate process carcinoma of the pancreas: clinical features and diagnosis and treatment].

OBJECTIVE: To summarize the clinical features and diagnosis and treatment of uncinate process carcinoma of the pancreas. METHODS: From January 1998 to December 2000, 41 patients of pancreas uncinate process carcinoma were retrospectly analysed. RESULTS: Upper abdominal pain accompanied with back pain,weight loss and jaundice were the main symptoms. Thirty-six patients were subjected to regional pancreaticoduodenectomy (RP), 11 to SMV-PV or SMA lateral wall partial resection or partial vascular resection and reconstruction, of which PV reconstruction with PTEE grafts was performed in 2 patients. Two cholecystojejunostomy Roux-en-Y. Alcohol injection was made in the nerve plexus of the trunks of both celic axes and the superior mesenteric artery and regional chemotherapy via chemotherapy pump and liver biopsy in one case. Abdominal exploration was performed in 1 case and no-operation in another. None of the cases died perioperatively. Postoperation survival 2 - 44 months and was 1 the median survival was 11.2 months. Four patients are still alive, the longest surviving have been 44 months. The 1-year and 3-year survival rate was 37.0% and 3.7%. CONCLUSIONS: Pancreas uncinate process carcinoma has a tendency to invade adjacent SMV/SMA-PV and is difficult to diagnose early. Since those are related to its location and not to its invading behaviors, the tumon is highly resecable (87.8%).

Aged↗