bluuebunny/crossref_metadata_2025 huggingface dataset:
Seroepidemiology of hepatitis A and hepatitis B virus infection in a Gurkha community in Singapore
Authors: Goh K. T. , Kong K. H. , Heng B. H. , Oon C. J.
Published: March 2007

The overall prevalence of hepatitis A virus (HAV) infection among the Gurkhas and their families stationed in Singapore was 83.2%, with antibody to HAV detected in 67 (38.1%) of 176 children under 5 years of age, 121 (76.6%) of 158 children between 5 and 14 years, and 600 (97.9%) of 613 older children and adults over age 15 years. Children born in Singapore (102/223 or 45.7%) had a significantly lower crude prevalence than those born in Nepal (85/110 or 77.3%) (P < 0.000001). The age‐adjusted difference in prevalence was also statistically significant (P < 0.001). Susceptible children had a high risk of acquiring HAV infection when they travelled to Nepal. As for hepatitis B virus (HBV) infection, the prevalence of hepatitis B surface antigen (HBsAg) was 2.8%, with a higher rate in males (20/560 or 3.6%) than in females (6/384 or 1.6%). The highest HBsAg prevalence (4/26 or 15.4%) was in young adult Gurkhas 15–19 years of age. No significant difference in the crude prevalence of HBV markers was noted between children born in Singapore (45/224 or 20.1%) and those born in Nepal (19/107 or 17.8%). Even after age adjustment, the difference remained insignificant. The prevalence of HBV markers of children of seropositive parents (27/156 or 17.3%) was not significantly higher than that of seronegative parents (19/131 or 14.5%). Married men had a significantly higher age‐adjusted prevalence of infection than unmarried men (45.4% and 32.4%, respectively; P < 0.05), Seropositivity of one spouse was significantly correlated with the seropositivity of the other (P < 0.05), suggesting a role for heterosexual transmission of HBV infection.
Transfer of humoral immunity against cytomegalovirus proteins following transplantation of T‐cell‐depleted allogeneic bone marrow from seropositive donors
Authors: Roy Donna M. , Brenner Malcolm K. , Cook Derek , Duncan R. Ian , Griffiths Paul D. , Grundy Jane E.
Published: March 2007

Previous work by Grob et al. [Lancet i:774, 1987] has demonstrated that allogeneic, T‐cell‐depleted bone marrow transplant recipients have a better prognosis for reactivated cytomegalovirus (CMV) infection if their donor is also immune. It was proposed that adoptively transferred humoral immunity was responsible for the protective effect of active infection. Immunoblot analysis using purified virions was used here to examine pre‐ and posttransplant antibody responses of seropositive recipients who had undergone active viral infection after transplantation. Immunoblots were assessed for the numbers of polypetides recognised and reactivity against individual polypeptides. Immunoblots were also scanned by quantitative densitometry, and the intensity of antibody responses against total viral protein and individual polypeptides was determined. Sera from recipients with immune donors exhibited a secondary‐type immune reponse in terms of both intensity and polypeptide specific pattern of antibody reactivity, compared with those recipients with nonimmune donors. In particular, recipients with immune donors appeared to show a greater reactivity against a protein of Mr 55,000; this may represent the envelope glycoprotein gB, which is a major target for neutralising antibodies, and might also be utilised for preparing an effective vaccine for CMV.
Current seroepidemiology of rubella virus infection among female residents in Taiwan
Authors: Lin Ding‐Bang , Chen Chien‐Jen
Published: March 2007

To examine the epidemiological characteristics of rubella virus infection on Taiwan Island and in Orchid and Pescadore islets, a community‐based survey was carried out in 19 townships and metropolitan precincts randomly selected through stratified sampling. Serum specimens of 4,770 healthy girls and women randomly sampled from study areas were screened for the rubella antibody by passive latex agglutination testing and confirmed by enzyme‐linked immunosorbent assay. A total of 2,934 subjects were antibody positive, giving a prevalence of 61.5%. The mean ± standard deviation of rubella IgG index was 2.51 ± 0.37. The seropositive rate increased with age in all residential areas and ethnic groups. The age pattern indicated that the regular 10‐year cycle of rubella epidemic was no longer existent after 1978. A higher prevalence was observed in the eastern island and Orchid Islets compared with other areas. The highest seropositive rate was found in Orchid Islets. The overall seronegative rate was 62.9% for females <20 years of age and 36.9% for women between the ages of 20 and 29 years. With such a high susceptible density among girls and women of child‐bearing ages as well as the endemicity of rubella virus infection in Taiwan, mass vaccination against rubella should be enforced in order to prevent possible future outbreaks of the congenital rubella syndrome.
Prevalence of hepatitis C virus in family members of patients with Hepatitis C
Authors: Oshita Masahide , Hayashi Norio , Kasahara Akinori , Yuki Nobukazu , Takehara Tetsuo , Hagiwara Hideki , Hayakawa Yuji , Yasumatsuya Yumi , Kishida Yutaka , Fusamoto Hideyuki , Kamada Takenobu
Published: March 2007

To investigate the prevalence of hepatitis C virus in the family members of patients with hepatitis C, we examined antibody to hepatitis C virus with a second‐generation enzyme‐linked immunosorbent assay and viral RNA with a combined assay of reverse transcription and polymerase chain reaction in sera. Among 219 (75 spouses, 110 children, and 34 others), 26 (12%) were antibody positive. The positive rate of antibody to hepatitis C virus was significantly higher than that of the control group (2.0%) and of volunteer blood donors in our district (1.5%), and it increased with age. In particular, the positive rate of antibody to hepatitis C virus among spouses was high (24%). Among family members with elevated ALT, 59% were antibody positive, which was significantly higher than that of the control group (11%). Of the 26 who were antibody positive, 21 (81%) had viral RNA, whereas of the 70 who were antibody negative, only one (1.4%) had viral RNA. These data suggest that hepatitis C virus was transmitted by the intrafamilial route during long duration of contact with patients or sexual transmission. In family members, hepatitis C viral infection is the main cause of liver disorder, and many who were antibody‐positive with a second‐generation enzyme‐linked immunosorbent assay had viremia in the sera.
Sequence variation within the human immunodeficiency virus V3 loop at seroconversion
Authors: Ait‐Khaled Mounir , Emery Vincent C.
Published: March 2007

Analysis of the HIV‐1 V3 quasispecies present in an individual at the time of seroconversion was carried out. The polymerase chain reaction (PCR) was used to amplify proviral HIV‐1 DNA extracted from peripheral blood mononuclear cells from a patient who was viraemic (p24 = 15 pg/ml) and had an equivocal HIV‐1 antibody status. The PCR products were cloned and the DNA sequence determined for 15 clones. These data showed that the V3 region contained only limited sequence heterogeneity with a major variant accounting for 66% of the protein quasispecies present. The protein sequence of the principal neutralising domain on all species contained the relatively rare GPGKTL motif rather than GPGRAF. The relevance of these data for early stages of HIV infection are discussed.
Evaluation of anti‐hepadnavirus activity of Phyllanthus amarus and Phyllanthus maderaspatensis in duck hepatitis b virus carrier Pekin ducks
Authors: Munshi Anupama , Mehrotra Raj , Ramesh Rajagopal , Panda Subrat K.
Published: March 2007

Extracts of the two traditional Indian herbs, Phyl lanthus amarus (P. amarus) and Phyllanthus maderaspatensis (P. maderaspatensis), described by others as useful in the treatment of chronic hepatitis B virus infection were studied for antiviral properties on duck hepatitis B virus infection. One hundred and fourteen ducks infected posthatch with the duck hepatitis B virus (DHBV) were divided into groups at three months of age and treated intraperitoneally with the aqueous, butanol, and alcoholic extracts of these two plants at doses of 25, 50, or 200 mg/kg body weight. Saline‐treated animals served as controls. In the ducks negative for DHBV in serum after treatment, we observed replicative intermediates in the liver. There was no definite antiviral property observed in the treated ducks.
T‐cell receptor Vα region usage in the cerebrospinal fluid of patients with mumps meningitis
Authors: Kimura Hiroshi , Ando Yoshihiro , Shibata Motohiro , Abe Tokuichiro , Morishima Tsuneo
Published: March 2007

To investigate clonality of local T cells in viral infections of the central nervous system, the T‐cell receptor (TCR) repertoire was evaluated in T cells from the cerebrospinal fluid (CSF) of nine patients with mumps meningitis, using the polymerase chain reaction (PCR) assay. The usage of the variable region of TCR α chain gene (Vα gene) in the CSF was widespread, and an average of 13 out of the 18 Vα families were expressed. Quantitative PCR analyses showed that the Vα gene expression was biased toward three or less Vα families in the CSF of each patient. When compared with peripheral blood T cells, the average percentages of Vα 11 and Vα 12 gene expression were significantly higher in the CSF than in the peripheral blood. These results suggested that mumps‐specific T lymphocytes with a restricted TCR repertoire are selectively recruited to the central nervous system in mumps meningitis, although polyclonal, probably nonspecific, T‐cell populations are present in the CSF.
Hepatitis C virus plus‐ and minus‐ strand RNA in hepatocellular carcinoma and adjoining nontumorous liver
Authors: Horiike Norio , Nonaka Takashi , Kumamoto Izumi , Kajino Kazunori , Onji Morikazu , Ohta Yasuyuki
Published: March 2007

The presence of hepatitis C virus (HCV) RNA in serum and liver tissue was examined in seven patients with hepatocellular carcinoma (HCC), using the reverse transcriptase‐polymerase chain reaction method with primers for the 5′‐noncoding region. Plus‐strand HCV‐RNA was detected in the serum and liver tissue (both cancerous and noncancerous tissue) of all five patients who were positive for anti‐HCV antibodies (C100‐3 and P22) and was not detected in both of two patients who were negative for anti‐HCV antibodies. Minus‐strand HCV‐RNA was only detected in the liver tissue (cancerous and noncancerous portion) of the five anti‐HCV antibodypositive patients. The relative liver tissue content of minus‐strand HCV‐RNA ranged from 1 to 100 time less than that of plus strand HCV‐RNA in cancerous and noncancerous tissue in each patient, respectively. There was no similar tendency in the HCV‐RNA content between the cancerous and noncancerous portions of the liver in each patient. These results suggest that HCV exists and replicates in HCC tissue and may have some role in the development of HCC.
Longitudinal study of hepatitis C viremia in chronic hepatitis C
Authors: Cheung Ramsey C. , Chan Rachel T. , Lok Anna S. F.
Published: March 2007

Serial serum samples from 20 untreated patients with chronic hepatitis C virus (HCV) infection were tested for HCV RNA by a nested polymerase chain reaction assay using primers from the highly conserved 5′ noncoding region to determine the relationship between hepatitis C viremia and the activity of liver disease during the natural course of chronic HCV infection. Semiquantitation of serum HCV RNA level was achieved by testing serial 10‐fold dilutions of RNA extracts to determine the end‐point titer. All the patients were HCV RNA positive at presentation. There was a poor correlation between the initial HCV RNA titer and serum transaminase levels. All patients except one were persistently HCV RNA positive during a follow‐up period of 1.5‐15 years, although 17 (85%) had periods of normal or near‐normal transaminase levels. There was no correlation between changes in the serum transaminase levels and HCV RNA titer. Patients with chronic HCV infection have persistent viremia despite fluctuations in ALT levels.
Variant of hepatitis B virus isolated in zimbabwe
Authors: Chirara Michael M. , Chetsanga Christopher J.
Published: March 2007

The polymerase chain reaction (PCR) was used to amplify an approximately 1.2 kb DNA fragment encompassing the pre‐S/S gene region of HBV DNA from serum of patients with acute hepatitis B virus infection. Nucleotide sequence analysis revealed a number of interesting features in the S gene region. Two Bam HI sites were located at nucleotide positions 557 and 872, respectively, in the S gene. Guanine (G) was found at nucleotide position 903 as part of AGA, the codon for arginine (R) corresponding to amino acid position 122 of the S protein. Ade‐nine (A) was found at nucleotide position 1017 as part of AXIA, the codon for lysine (K) corresponding to amino acid position 160 of the S protein. Nucleotide sequence alignment revealed a 97% homology to the corresponding domain of an HBVadw genome (clone pFDW294). Within the second loop of the “a” determinant, two mutations resulting in substitution of serine or threonine with the hydrophobic amino acids, methio‐nine at position 143 and with alanine in place of glycine at position 145, are predicted from the consensus nucleotide sequence of the PCR‐derived clones. Subtyping with monoclonal antibodies showed that the HBsAg was of the ayw subtype. © 1994 Wiiey‐Liss, Inc.
Serological response to rotavirus infection in newborn infants
Authors: Floras Jorge , White Laura , Blanco Mario , Perez‐Schael Irene
Published: March 2007

We report the identification of rotavirus in stools of newborn infants at the “Hospital Materno Infantil de Caricuao” (HMIC) as well as the infants' serological responses to various rotavirus strains. The serological responses of another group of rotavirus‐positive neonates studied previously at the “Maternidad Concepcion Palacios” (MCP) hospital was also evaluated. Fifty‐four of 266 (20%) newborns examined at HMIC shed rotavirus. The infection rate was higher among infants admitted to the nursery (75%) than in those “rooming in” with their mothers (7%) (P < 0.01). Eleven of the 54 neonates (20%) had diarrhea; seven of them experienced mild, short‐lived episodes, whereas five had frequent diarrhea bouts or diarrhea lasting for over 3 days; the remaining 43 infants were asymptomatic. Twenty‐seven of 28 rotavirus specimens tested at HMIC had VP7 serotype 4 specificity and one belonged to VP7 serotype 1; VP4 typing performed on 24 of the viruses by RNA hybridization showed these viruses to be similar to the M37 strain, a rotavirus previously associated with asymptomatic infections in newborns at MCP. IgA seroresponses were detected in eight of 11 infants born at HMIC (73%), but most failed to developed neutralization responses to homologous or heterologous strains. Newborn infants who had shed the M37 rotavirus strain at MCP reacted similarly: 16 of 24 (67%) developed a rotavirus IgA rise, but only 29% developed a neutralization response. © 1994 Wiiey‐Liss, Inc.
Dengue virus infects mouse cultured neurons but not astrocytes
Authors: Imbert Jose Luis , Guevara Patricia , Ramos‐Castañeda Jose , Ramos Celso , Sotelo Julio
Published: March 2007

Cultures of mouse brain cells containing a high proportion either neurons or astrocytes were inoculated with various strains of dengue virus. At analysis by double immunofluorescence, all strains of dengue virus studied were tropic for neurons. In no case were the astrocytes infected. Only ∼10% of all neurons were infected, suggesting that the virus may enter the cell through a membrane receptor present only in a subgroup of neurons. © 1994 Wiley‐Liss, Inc.
Detection of hepatitis C viral sequences in formalin‐fixed, paraffin‐embedded liver tissue: Effect of interferon alpha therapy
Authors: Diamond David A. , Davis Gary L. , Qian Ke‐Ping , Lau Johnson Y. N.
Published: March 2007

To determine the effect of interferon‐α (IFN) therapy on hepatitis C virus (HCV) in liver, reverse transcription “nested” polymerase chain reaction (RT‐PCR) was applied to detect HCV RNA in formalin‐fixed, paraffin‐embedded liver biopsy specimens obtained before and at the end of IFN therapy in 42 patients with chronic HCV infection. Results were correlated with the clinical and biochemical outcome in 36 cases. Fifteen patients were nonresponders to IFN; 13 patients had a complete response to IFN but relapsed shortly after IFN was stopped (responders who relapsed); and 8 patients showed a complete and sustained response to IFN therapy (sustained responders). Total RNA was extracted using proteinase K digestion and phenol/chloroform/ isoamyl alcohol extraction, and HCV RNA was detected by standard RT‐PCR using primers from the highly conserved 5′ untranslated region. HCV RNA was detected in 41 of the 42 pretreatment specimens. Of the 36 patients with paired posttreatment samples, HCV RNA was detected in all 15 patients who did not respond to IFN and 9 of 13 who responded to IFN but relapsed shortly after IFN was stopped. In contrast, only one of the eight patients who had a sustained response to IFN therapy had HCV RNA detected by RT‐PCR (P < 0.04). These data confirm 1) the feasibility of detecting HCV RNA in formalin‐fixed, paraffin‐embedded tissue from patients with chronic HCV infection, 2) show that sustained response to IFN is associated with loss of liver HCV RNA at the end of IFN therapy, and 3) offer an explanation for recurrence in patients who relapse. © 1994 Wiley‐Liss, Inc.
Association of cytomegalovirus infection with post‐transplantation cardiac rejection as studied using the polymerase chain reaction
Authors: Fernando Sirimali , Booth James , Boriskin Yuri , Butcher Philip , Carrington David , Steel Helen , Tryhorn Yvonne , Corbishley Catherine , Keeling Philip , Murday Andrew , McKenna William
Published: March 2007

The relationship between cytomegalovirus (CMV) infection and cardiac allograft rejection is controversial, some authors reporting a significant association, others not, on the basis of the results of conventional virological diagnosis by culture or serology. This problem was reinvesti‐gated in 88 patients using a semi‐quantitative nest polymerase chain reaction (PCR) procedure for detecting CMV DNA in endomyocardial biopsy specimens. Significantly more positive biopsies were obtained from patients with moderate (grade 2; P = 0.02) or severe (grade 3a‐4; P = 0.03) rejection than with no or mild (grade 0‐1 b) rejection, whereas there was no significant association between rejection and CMV as diagnosed by virus isolation from urine, throat or blood, or by the detection of CMV‐IgM.

PCR‐positive biopsies originated most frequently from CMV‐antibody positive recipients (R+) of hearts from seropositive donors (D+), in association with moderate or severe rejection rather than with mild or no rejection The detection of CMV in the heart thus seemed to be related more to R+D+ serological status than to severity of rejection, that is, to circumstances that favoured co‐infection with strains of CMV from both donor and recipient. Studies on sequential biopsy specimens from selected patients also provided evidence that CMV infection and rejection were not always related events.

The PCR was able to differentiate latent from active CMV infection; moreover, some seroneg‐ative individuals gave repeatedly positive biopsies, thereby supporting the work of others that some patients undergo CMV infection without mounting a detectable antibody response.

The use of the PCR provided additional and more definitive information linking CMV and post‐transplantation cardiac rejection when compared to conventional methods of viral diagnosis which were less suitable as correlates of deep seated focal infection. © 1994 Wiley‐Liss, inc.
Epidemiology of hepatitis C virus in Western Venezuela: Lack of specific antibody in indian communities
Authors: Blitz‐Dorfman Linda , Monsalve Francisca , Porto Leticia , Weir Jesús , Arteaga Melvis , Padrón Guillermo , León Pilar , Echevarría José M.
Published: March 2007

Hepatitis C virus (HCV) is transmitted mainly by the parenteral route after percutaneous exposure to virus‐infected products or body fluids. Thus, HCV shares with hepatitis B and D (HBV, HDV) viruses this common transmission route. The prevalence of antibody against HCV (anti‐HCV) was studied in 1155 serum samples from individuals at risk of infection by bloodborne or sexually transmitted agents, as well as from others lacking such risk factors, from the city of Maracaibo, Venezuela. Anti‐HCV and serological markers of infection by HBV and HDV were also studied in further 550 samples taken from Bari Indians living in different communities in the Perija mountains. State of Zulia, Venezuela. The results obtained showed that recipients of blood or blood products are at increased risk of HCV infection in Maracaibo, whereas sexual transmission plays only a minor role if any. Both HBV and HDV infections were highly prevalent among Bari Indians (64.4% positive for anti‐HBc; 11.1% of HBsAg carriers; 15.3% positive for anti‐HDV among HBsAg carriers). No anti‐HCV positive samples were, however, detected among them, thus suggesting either that HCV has not still reached this population or that HBV and HDV are transmitted by routes unshared by HCV. Anti‐HCV was also absent among samples from mentally retarded patients from Maracaibo, thus confirming similar findings from other countries and supporting the existence of specific transmission mechanisms for HBV and HDV which are not working for HCV. © 1994 Wiley‐Liss, Inc.
Characterization of substituted polyacetylene microstructure by pyrolysis gas chromatography
Authors: Doležal Zdeněk , Kubinec Róbert , Sedláček Jan , Pacáková Vera , Vohlídal Jirí
Published: March 2007

A series of substituted acetylenes has been polymerized with WOCl4/Ph4Sn metathesis catalyst and [Rh(cod)OMe]2 insertion catalyst, and the thermal degradation of the polyacetylenes prepared has been studied using pyrolysis capillary gas chromatography (Py‐GC) with flame ionization and mass spectrometric detection to obtain information on the effect of the catalyst on the head‐tail (H‐T) isomerism of polyacetylenes (poly(phenylacetylene), poly[(4‐methylphenyl)acetylene], poly(benzylacetylene), poly[(2‐fluorophenyl)acetylene], poly[(3‐fluorophenyl)acetylene], and poly[(4‐fluorophenyl)acetylene]). Cyclotrimers have been found to be the main pyrolysis products in all cases. Direct Py‐MS connection was used to determine the temperature profiles of the released pyrolysis products. 1,3,5‐Trisubstituted benzenes were found to be the predominant pyrolysis products of the polymers prepared with the insertion catalyst, which proves the presence of long head‐to‐tail sequences of monomeric units in these polyacetylenes. On the other hand, both 1,2,4‐ and 1,3,5‐trisubstituted benzenes are present in significant amounts in the pyrolysis products of polymers prepared with the metathesis catalyst, which proves the presence of a significant content of the head‐to‐head (HH) and tail‐to‐tail (TT) linkages in these isomers of polyacetylenes. Contents of the regular (HT) and inverse (HH‐TT) monomer linkages (RML and IML, respectively) in polymer chains were determined from the relative amounts of di‐, tri‐, and tetrasubstituted benzenes found in the Py‐GC products.
On RD‐rational Krylov approximations to the core‐functions of exponential integrators
Authors: Moret I.
Published: March 2007

The paper deals with the application of the restricted‐denominator rational Krylov method, recently discussed in (BIT 2004; 44(3):595–615; SIAM J. Sci. Comput. 2005; 27:1438–1457), to the computation of the action of the so‐called φ‐functions, which play a fundamental role in several modern exponential integrators. The analysis here presented is devoted in particular to the construction of error estimates of easy practical use. Copyright © 2007 John Wiley & Sons, Ltd.
H(curl) auxiliary mesh preconditioning
Authors: Kolev Tzanio V. , Pasciak Joseph E. , Vassilevski Panayot S.
Published: March 2007

This paper analyses a two‐level preconditioning scheme for H(curl) bilinear forms. The scheme utilizes an auxiliary problem on a related mesh that is more amenable for constructing optimal order multigrid methods. More specifically, we analyse the case when the auxiliary mesh only approximately covers the original domain. The latter assumption is important since it allows for easy construction of nested multilevel spaces on regular auxiliary meshes. Numerical experiments in both two and three space dimensions illustrate the optimal performance of the method. Published in 2007 by John Wiley & Sons, Ltd.
Boundary‐conforming coordinates with grid line control for acoustic scattering from complexly shaped obstacles
Authors: Villamizar Vianey , Weber Matthew
Published: March 2007

The current work sets forth a practical approach to numerically solve two‐dimensional direct acoustic scattering problems from complexly shaped scatterers with severe singularities, such as corners and cusps. First, boundary conforming coordinates are generated. This generation is performed through an elliptic grid generator algorithm, including control of the coordinate lines. The grid line control solely depends on the initial distribution of grid points. Following the grid generation process, the initial boundary value problem, modelling the scattering phenomenon, is formulated in terms of the new curvilinear coordinates, and a finite‐difference time domain method is implemented. The presence of the boundary singularities causes instability of the numerical method. However, by appropriately controlling the distance between grid lines in the vicinity of these singularities, stability and convergence are achieved. A semianalytical formula for the differential scattering cross‐section is obtained from the discrete Fourier transform of the computed scattered pressure field. The method is successfully applied to several interesting scatterers of various shapes. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007
Nasopharyngeal carcinoma: a review of its causes and its diagnosis in skeletal material
Authors: Mark S.
Published: March 2007

Smoky fires in small, poorly ventilated structures have been cited as a risk factor for nasopharyngeal carcinoma (NPC) since the 1920s (Dobson, 1924). Furthermore, based on five cited cases of ancient NPC, it has been proposed that NPC was a common condition with a wide geographical distribution in ancient populations (Wells, 1964a,b). Both interpretations have continued to appear in the literature (Ortner, 2003), but recently, Aufderheide & Rodríguez‐Martín (1998) have argued that the number of cases of NPC is inflated due to ‘diagnostic imprecision’. This paper reviews medical advances that in the last few decades have shed considerable light on risk factors for NPC, and also reviews criteria for diagnosing NPC. Based on these data, a reexamination of the five cited cases of ancient NPC suggests that only one case may be NPC, and the prevalence and distribution of this disease may have been more variable than originally thought. Furthermore, a better understanding of the aetiology of NPC and criteria for diagnosis may allow for more precise research designs for studying ancient populations. Copyright © 2007 John Wiley & Sons, Ltd.
Kinetic study on copolymerization of ethylene and 1‐hexene catalyzed by Cp2ZrCl2/MAO catalytic system
Authors: Wang Jianfeng , Wang Li , Gao Haoqi , Wang Wenqin , Jiang Guohua , Dong Xiaocheng , Wang Wei , Feng Lianfang
Published: March 2007

The kinetics of ethylene and 1‐hexene copolymerization catalyzed by Cp2ZrCl2/MAO was studied. A new kinetic mathematical model that takes the reactivation effect of MAO into account has been developed. Applying this model, the good agreement between the experimental data and the fitting profiles was achieved. POLYM. ENG. SCI., 47:540–544, 2007. © 2007 Society of Plastics Engineers
Multiple criteria optimization with variability considerations in injection molding
Authors: Castro Carlos E. , Ríos Mauricio Cabrera , Castro José M. , Lilly Blaine
Published: March 2007

Injection molding (IM) is the most important process for mass‐producing of plastic products. The difficulty of optimizing an IM process is that the performance measures (PMs) usually show conflicting behavior. The aim of this work is to demonstrate a method utilizing CAE, statistical testing, artificial neural networks (ANNs), and data envelopment analysis (DEA) to find the best compromises between multiple PMs, considering the variability in these PMs in an explicit manner. Two case studies are presented. The first case study, based on a virtual part, is discussed in detail in order to illustrate this method. The second case study is experimentally based and makes use of the American Society of Testing Materials (ASTM) mold to illustrate how this approach applies when purely experimental results are available. POLYM. ENG. SCI., 47:400–409, 2007. © 2007 Society of Plastics Engineers
Experimental characterization and computational simulations of the impact behavior of injection‐molded polymers
Authors: Viana Júlio C. , Cunha António M. , Billon Noelle
Published: March 2007

The multiaxial impact test in polymers is analyzed. The impact response of a propylene copolymer is characterized under different test conditions. Due to the nature of the impact event and to the complex material behavior, an intricate stress state is developed rendering rather difficult the assessment of the intrinsic impact properties. Furthermore, processing determine polymer microstructure, which significantly influences the impact response. The multiaxial impact test was simulated using a finite element code. The computed force‐displacement curves fall in between the computed ones with two extreme contact conditions between striker and plate. Friction plays an important role from medium strain levels until the peak force is reached, determining its intensity. The constitutive coefficients at high strain‐rates were identified by an inverse method. The adopted constitutive model allows the computation of the force‐deflection curve until the force peak, but not its full description. For that, a modified version was used that more correctly takes into account the strain hardening of the polymer. Finally, it is emphasized the importance of the knowledge of the heat conversion factor for realistically predicting the mechanical behavior of polymers at high strain‐rates. POLYM. ENG. SCI., 47:337–346, 2007. © 2007 Society of Plastics Engineers.
Intrinsic lifetime of polyethylene pipelines
Authors: Brown Norman
Published: March 2007

An equation was developed for calculating the time to failure by slow crack growth (SCG) failure in any polyethylene structure. The equation requires the following experimental inputs: (1) the resistance to SCG as measured by the PENT test (ASTM F1473), (2) the stress intensity of the defect from which failure originates, and (3) the temperature. A simple experiment for determining the stress intensity is presented. The equation was applied to SCG failures that are associated with the inherent random defects that occur in the wall of all pipes. The size of the inherent random defect that exists in commercial gas pipes was found to be 0.14 mm. POLYM. ENG. SCI., 47:477–480, 2007. © 2007 Society of Plastics Engineers.
Application of a capacitive transducer for online part weight prediction and fault detection in injection molding
Authors: Fung Ka Tsai , Gao Furong , Chen Xi
Published: March 2007

This article extends the applications of in‐mold capacitive transducer to packing stage for on‐line part weight prediction and check‐ring failure detection for injection molding. Experiments under various conditions show that the proposed on‐line part weight prediction is robust and effective, which may pave the way for on‐line closed‐loop part weight control. POLYM. ENG. SCI., 47:347–353, 2007. © 2007 Society of Plastics Engineers.
Nonisothermal crystallization behavior of poly(ϵ‐caprolactone)/attapulgite nanocomposites by DSC analysis
Authors: Liu Qi , Peng Zhiqin , Chen Dajun
Published: March 2007

Nanocomposites based on biodegradable poly(ε‐caprolactone) (PCL) and attapulgite (AT) were prepared by solution mixing. The nonisothermal crystallization of the pure PCL and PCL/AT nanocomposites at different AT contents and different cooling rates were investigated by differential scanning calorimetry (DSC). There are significant dependence of nonisothermal crystallization behavior and kinetics of PCL/AT nanocomposites on the AT content and cooling rate. The Jeziorny method has been employed to analyze the DSC data. The results show that Jeziorny method could describe this system well. It can be concluded that AT can be used as an effective nucleating agent and has effects on the growth of crystallites in the crystallization process of PCL matrix. POLYM. ENG. SCI., 47:460–466, 2007. © 2007 Society of Plastics Engineers.
Effect of nucleating additives on crystallization of poly(m‐xylylene adipamide)
Authors: Naudy Sophie , Fulchiron René
Published: March 2007

Static crystallization study was carried out on virgin and nucleated poly(m‐xylylene adipamide) (MXD6) which were, respectively, named PA1 and PA2. For PA2, the nucleating additives consist in talc (1%) and PA66 (11%). The three used experimental techniques (rheometer, calorimetry, and a hot stage coupled with an optical microscope) showed complementary results as the DSC could not be used to measure the low crystallization kinetics of PA1. Characteristic crystallization times were measured according to the crystallization conditions (temperature, cooling rate). Isothermal crystallization study allowed the determination of the thermodynamic melting point of the MXD6 and the description of the lamellae growth rate by the Hoffman–Lauritzen equation. For PA2, the creation of a soft network due to PA66 crystallization prior to the MXD6 crystallization was highlighted thanks to a specific rheological study. Lastly, kinetic models, based on both Avrami and Hoffman–Lauritzen theories, were proposed to depict the crystallization process. POLYM. ENG. SCI., 47:365–373, 2007. © 2007 Society of Plastics Engineers.
Influence of wall thickness on the creep rupture performance of polyethylene pipe
Authors: Krishnaswamy Rajendra K.
Published: March 2007

A thermal gradient is inherent to the solidification of extruded profiles such as pipes. Depending on the magnitude of the gradient, varying levels of residual stresses are frozen‐in during the pipe fabrication step. In this investigation, the residual stress state of a polyethylene (PE) pipe was altered by changing its wall thickness. Creep rupture testing of the subject pipes of varying wall thickness provided an insight on how residual stresses influences both ductile and brittle fracture processes. POLYM. ENG. SCI., 47:516–521, 2007. © 2007 Society of Plastics Engineers.
Crystallization kinetics and morphology of the mesomorphic form of syndiotactic polypropylene
Authors: Pucciariello Rachele , Villani Vincenzo , Cascone Alfonso , Guadagno Liberata , Vittoria Vittoria
Published: March 2007

For the first time the kinetics of formation of syndiotactic polypropylene mesophase close to 0 °C through differential scanning calorimetry has been investigated. The calorimetric data have been analyzed through the well‐known Avrami analysis. We have obtained Avrami coefficients less or at most equal to 2, which are likely to indicate a nearly bidimensionality of the crystallites. The morphology of the mesophase, not known up to now, has been examined through atomic force microscopy (AFM): lamellar structures have been observed. The fractal dimension of the AFM images has been evaluated through the box counting method. It resulted about 2, in a very good agreement with the calculated Avrami coefficients. An infrared and diffractometer analysis on samples kept for increasing times at 0 °C has also been performed to confirm the calorimetric data. The experimental results allow one to better clarify the kinetics of mesophase‐formation. It has been found that a time of 3 h at 0 °C is actually necessary for the complete crystallization of the trans‐planar mesophase, a longer time is needed to stabilize the mesophase domains when the sample is extracted from 0 °C at room temperature. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 936–944, 2007
Heterogeneity of glass transition dynamics in polyurethane‐poly(2‐hydroxyethyl methacrylate) semi‐interpenetrating polymer networks
Authors: Karabanova L. V. , Sergeeva L. M. , Svyatyna A. V. , Yakushev P. N. , Egorova L. M. , Ryzhov V. A. , Bershtein V. A.
Published: March 2007

The peculiarities of segmental dynamics over the temperature range of −140 to 180 °C were studied in polyurethane‐poly(2‐hydroxyethyl methacrylate) semi‐interpenetrating polymer networks (PU‐PHEMA semi‐IPNs) with two‐phase, nanoheterogeneous structure. The networks were synthesized by the sequential method when the PU network was obtained from poly(oxypropylene glycol) (PPG) and adduct of trimethylolpropane (TMP) and toluylene diisocyanate (TDI), and then swollen with 2‐hydroxyethyl methacrylate monomer with its subsequent photopolymerization. PHEMA content in the semi‐IPNs varied from 10 to 57 wt %. Laser‐interferometric creep rate spectroscopy (CRS), supplemented with differential scanning calorimetry (DSC), was used for discrete dynamic analysis of these IPNs. The effects of anomalous, large broadening of the PHEMA glass transition to higher temperatures in comparison with that of neat PHEMA, despite much lower Tg of the PU constituent, and the pronounced heterogeneity of glass transition dynamics were found in these networks. Up to 3 or 4 overlapping creep rate peaks, characterizing different segmental dynamics modes, have been registered within both PU and PHEMA glass transitions in these semi‐IPNs. On the whole, the united semi‐IPN glass transition ranged virtually from −60 to 160 °C. As proved by IR spectra, some hybridization of the semi‐IPN constituents took place, and therefore the effects observed could be properly interpreted in the framework of the notion of “constrained dynamics.” The peculiar segmental dynamics in the semi‐IPNs studied may help in developing advanced biomedical, damping, and membrane materials based thereon. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 963–975, 2007
Effect of tube length on the chemisorptions of one and two hydrogen atoms on the sidewalls of (3,3) and (4,4) single‐walled carbon nanotubes: A theoretical study
Authors: Kaczmarek Anna , Dinadayalane T. C. , Łukaszewicz Jerzy , Leszczynski Jerzy
Published: March 2007

Density functional theory (B3LYP) calculations using 3‐21G and 6‐31G(d) basis sets were performed for four different lengths of (3,3) and (4,4) armchair single‐walled carbon nanotubes to examine the effect of tube length on the chemisorption process. The significant changes in the CC bond lengths by H‐chemisorption are due to the change of hybridization of carbon atom(s) from sp2 to sp3 at the chemisorption site(s). In general, 3‐21G basis set overestimates the bond distances and reaction exothermicities compared to 6‐31G(d) basis set; however, both the basis sets reveal similar trend. The exothermicity for the addition of two H atoms is about 2–2.5 times that of one H chemisorption except for H (1,3) addition. The present study reveals that the positional preference for the chemisorption of two hydrogen atoms is not same for the armchair and zigzag type nanotubes. The reaction energies for hydrogen chemisorption on the surface of (3,3) nanotubes are substantially higher than for (4,4) SWNTs, probably due to the greater curvature and larger strain in the former case. The change of tube length has significant effect on the reaction energies of hydrogen chemisorption and band gap values. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
Rotationally Invariant Multipartite States
Authors: Chruściński Dariusz , Kossakowski Andrzej
Published: March 2007

We construct a class of multipartite states possessing rotational SO (3) symmetry — these are states of K spin-jA particles and K spin-jB particles. The construction of symmetric states follows our two recent papers devoted to unitary and orthogonal multipartite symmetry. We study basic properties of multipartite SO (3) symmetric states: separability criteria and multi-PPT conditions.
Flow, mixing, and displacement in using a data‐based hydrochemical model to predict conservative tracer data
Authors: Iorgulescu I. , Beven K. J. , Musy A.
Published: March 2007

We extend the data‐based hydrochemical model of Iorgulescu et al. (2005), able to simulate discharge and reactive chemical tracer concentrations (silica and calcium) in streamflow for subcatchments of the Haute‐Mentue research basin (Switzerland), to the prediction of additional δ18O values treated as a conservative tracer. The hydrochemical model is based on a parameterization of three runoff components (direct precipitation (DP), acid soil water (AS), and deep groundwater (GW)) in a chemical mixing model. Each component is modeled through an identical structure consisting of a nonlinear gain and a linear transfer function with two reservoirs (fast/slow) in parallel having a constant partition between them. We formulate a set of hypotheses concerning the isotope characterization of each component to provide additional information about how new rainfall inputs are processed in the hydrological response of the catchment. In particular, the AS component is modeled through a nested structure of hypotheses (models) of increasing complexity. It will be shown that hydrological processes in the hillslope associated with the DP, AS, and GW components are especially effective in filtering of higher‐frequency fluctuations in precipitation isotopic ratios at the intraevent, interevent/seasonal, and annual/multiannual timescales. The highly nonlinear and nonstationary AS component represents predominantly “recent” water stored in the upper decimeters of the soil profile. Results also suggest that subsurface pathways are significant for the DP component. A local flow path mechanism is proposed for explaining the large fluxes of subsurface flows.
A representative time‐series for the Southern Hemisphere zonal wave 1
Authors: Hobbs W. R. , Raphael M. N.
Published: March 2007

Recent studies show that an ENSO component of west Antarctic climate variability is related to a persistent zonal pressure anomaly in the south Pacific, which in turn is related to the zonal wave 1 of the subpolar atmospheric circulation. In order to promote further investigation into its dynamics, a suite of time series are presented that describe the intensity and location of ZW1. These time series are shown to represent the SH zonally asymmetric circulation reasonably well. Analysis of the time series suggests that, consistent with previous research, there was a poleward and eastward shift in ZW1 over the late 20th Century. There was also an increase in amplitude variance over this period. Cross‐correlation confirms a link with ENSO, and suggests a link between the subtropical and subpolar ZW1. Results also indicate a significant local interaction between south Pacific sea surface temperature and the intensity and location of ZW1.
Crustal deformation of the Yellowstone–Snake River Plain volcano‐tectonic system: Campaign and continuous GPS observations, 1987–2004
Authors: Puskas C. M. , Smith R. B. , Meertens C. M. , Chang W. L.
Published: March 2007

The Yellowstone–Snake River Plain tectonomagmatic province resulted from Late Tertiary volcanism in western North America, producing three large, caldera‐forming eruptions at the Yellowstone Plateau in the last 2 Myr. To understand the kinematics and geodynamics of this volcanic system, the University of Utah conducted seven GPS campaigns at 140 sites between 1987 and 2003 and installed a network of 15 permanent stations. GPS deployments focused on the Yellowstone caldera, the Hebgen Lake and Teton faults, and the eastern Snake River Plain. The GPS data revealed periods of uplift and subsidence of the Yellowstone caldera at rates up to 15 mm/yr. From 1987 to 1995, the caldera subsided and contracted, implying volume loss. From 1995 to 2000, deformation shifted to inflation and extension northwest of the caldera. From 2000 to 2003, uplift continued to the northwest while caldera subsidence was renewed. The GPS observations also revealed extension across the Hebgen Lake fault and fault‐normal contraction across the Teton fault. Deformation rates of the Yellowstone caldera and Hebgen Lake fault were converted to equivalent total moment rates, which exceeded historic seismic moment release and late Quaternary fault slip‐derived moment release by an order of magnitude. The Yellowstone caldera deformation trends were superimposed on regional southwest extension of the Yellowstone Plateau at up to 4.3 ± 0.2 mm/yr, while the eastern Snake River Plain moved southwest as a slower rate at 2.1 ± 0.2 mm/yr. This southwest extension of the Yellowstone–Snake River Plain system merged into east‐west extension of the Basin‐Range province.
Landscape‐scale variability of acidity and dissolved organic carbon during spring flood in a boreal stream network
Authors: Buffam Ishi , Laudon Hjalmar , Temnerud Johan , Mörth Carl‐Magnus , Bishop Kevin
Published: March 2007

Acidity is well known to influence stream biota, but the less well‐studied spatial and temporal distributions of acidity are likely to play a larger ecological role than average values. We present data on spatial variability of chemical parameters contributing to acidity during winter baseflow and spring flood periods in Krycklan, a fourth‐order boreal stream network in northern Sweden. Fifteen stream sites were monitored in subcatchments spanning 3 orders of magnitude in size and representing a wide range of percent wetland. At baseflow, pH ranged from 3.9 to 6.5 at the different sites. Baseflow dissolved organic carbon (DOC) concentration varied by an order of magnitude and was positively correlated with subcatchment percent wetland, resulting in high spatial variability in dissociated organic acids (OA−). During spring flood, DOC and OA− increased in forested sites and decreased in wetland sites, resulting in reduced spatial variability in their concentrations. In contrast, base cations and strong acid anions diluted throughout the stream network, resulting in decreased acid neutralizing capacity (ANC) at all sites. The spatial variability of base cations increased slightly with high flow. As a result of the changes in OA− and ANC, pH dropped at all but the most acidic site, giving a slightly narrowed pH range during spring flood (4.2–6.1). The transition from winter to spring flood stream chemistry could largely be explained by: (1) a shift from mineral to upper riparian organic soil flow paths in forested catchments and (2) dilution of peat water with snowmelt in wetland catchments.