bluuebunny/crossref_metadata_2025 huggingface dataset:
Interactions of Iron and Viscoelastic Surfactants During Well Stimulation: A New Formation Damage Mechanism
Authors: Al-Nakhli Ayman R. , Nasr-El-Din H. A. , Al-Baiyat A. A.
Published: April 2008

Viscoelastic surfactant-based acids have been extensively used over the last few years in matrix and acid fracturing treatments. Two main types of viscoelastic surfactants have been used; amphoteric and cationic. Once the acid reacts with the carbonate formation and the pH increases above two and the concentrations of calcium and magnesium ions increases, these surfactants form a long rod shaped micelles. As a result, the viscosity of the solution increases significantly. This will result in better acid diversion in matrix acid treatments and deeper acid penetration in acid fracturing treatments.

Viscoelastic surfactant-based acids were used in more than 600 successful treatments. The results, however from some treatments were below expectations. Analysis of the live acid used in one unoptimum treatment indicated that this acid contained nearly 10,000 mg/l total iron. It was clear that there were some interactions between iron and the viscoelastic surfactant used. Therefore, this study was conducted to better understand interactions between iron and various types of viscoelastic surfactants. All tests were conducted on live acid that contained 3 & 20 wt% HCl, 4 to 6 vol% surfactant, and 0.3 vol% corrosion inhibitor. Ferric chloride was added to the live acids at various concentrations from 0 to 10,000 mg/l.

Compatibility tests indicated that there are strong chemical interactions between iron (III) and all types of viscoelastic surfactants examined. A gel like material was noted at a certain iron concentration. SEM analysis indicated that the gel-like material contained iron. Also analysis of the iron in the supernatant using ICP confirmed this result. The critical iron concentration was found to be a function of the surfactant type. Extensive lab testing indicating that there is interactions between iron and the amide and amine groups present in these surfactants. Corrosion inhibitors contain amine and amide groups, and they did affect the interactions between iron and viscoelastic surfactants. These interactions resulted in the formation of the gel-like material that can cause sever formation damage. This paper will discuss the results obtained and give recommendations to avoid the formation of such damaging material.
In Defense of Indices: The Case of Bird Surveys
Authors: JOHNSON DOUGLAS H.
Published: April 2008

Abstract: Indices to population size have come under increasing criticism in recent years, on the grounds that indices might not faithfully represent the entire population. Most criticisms involve surveys of birds, particularly those based on point counts, which is my focus here. A variety of quantitative methods have been developed to reduce the bias of point counts, such as distance sampling, multiple‐observer surveys, and time‐of‐detection methods. I argue that these developments are valuable, in that they enhance understanding of the detection process, but that their practical application may well be limited, likely to intensive studies focusing on a small number of species. These quantitative methods are not generally applicable to extensive, multiple‐species surveys. Although criticism of the thoughtless use of indices is welcome, their wholesale rejection is not.
Using the TL Single-Aliquot Regenerative-Dose Protocol for the Verification of the Chronology of the Teutonic Order Castle in Malbork
Authors: Chruścińska Alicja , Jesionowski Bernard , Oczkowski Hubert , Przegiętka Krzysztof
Published: April 2008

The Teutonic Order Castle in Malbork is one of the precious medieval monuments in Europe. Because of the lack of natural rock resources in Pomerania, its walls are built almost exclusively of bricks. The huge volume and rich historical knowledge about the Malbork Castle makes it a marvellous object for TL dating. The parts of well known age can serve for the verification and improvement of dating method. Subsequently, gained in such way knowledge and experience can be applied for discovering the history of the rest of the castle. Here, the preliminary results of investigations which are still in progress, are presented for 5 brick samples. The applied TL dating procedure is described in detail. The very good accuracy of equivalent dose is achieved by the TL single-aliquot regenerative-dose protocol. The effect of wall inhomogeneity connected with the difference between the activity of the brick and mortar is discussed.
Environmental Cosmopolitans
Authors: Campbell Ben
Published: April 2008

Cosmopolitanism has become a rediscovered conceptual frontier within the social sciences. It has emerged in the space for relational thinking about contemporary movements of people and ideas beyond old societal boundaries, as an alternative to the homogenizing implications carried by globalization. It forefronts new cross-territorial contexts of encounter attending to samenesses and differences among people, places, and the nonhuman, presenting new kinds of translocal issues for anthropologists of the environment. While cosmopolitanism draws historically on aspects of Enlightenment universalist rationalism, current applications of the term forefront an empathy and respect for other people’s cultures and values. This is frequently drawn into a distinction between “normative” and “cultural” cosmopolitanisms. The first Kantian sense involves a context-transcendent level of ethical principles with general validity, while the second is about taking cognizance of difference and invokes some positive tolerance of multiplicity and appreciation of others. In both cases there is a sense of a projected “ethical horizon” (Werbner 2008).
The role of the soil seed bank in vegetation recovery on an oceanic island severely damaged by introduced goats
Authors: Weerasinghe Udayani R. , Akiko Shimizu , Palitha Jayasekara , Seiki Takatsuki
Published: April 2008

Question: Are the seed banks of an isolated subtropical oceanic island capable of naturally regenerating vegetation either with species of the historical forest community or with the existing grassland community after severe damage to the vegetation by goats?

Location: Nakoudojima Island, Bonin Archipelago (Ogasawara Shoto), Japan.

Methods: Soil samples were collected at 0–5 cm and 5–10 cm depths from seven plots in forests, grasslands, artificially matted areas and bare land. Soil seed banks were assessed using the seedling emergence method followed by the hand‐sorting of ungerminated seeds. We determined the size and composition of the seed banks in upper soil layers of plots and compared the seed banks to the standing vegetation.

Results: A total of 12 220 seedlings belonging to 42 species from 20 families germinated. Total mean seed density (0–5 cm depth) was low in all plots within forest, grassland, and heavily degraded vegetation types (34.7 ± 8.6 to 693.5 ± 123.6, 58.6 ± 7.8 to 107.1 ± 10.0, and 1.1 ± 0.5 to 7.2 ± 2.3 seeds/m2, respectively). Forbs and graminoids dominated the seed banks of grassland and forest plots including Cyperus brevifolius, Gnaphalium pensylvanicum, Oxalis corniculata and Solanum nigrum, and these alien species comprised 90% of the density of the seed bank. There was little correlation between seed banks and standing vegetation of the island (Sørensen similarity coefficient values 0.26 to 0.45).

Conclusions: If natural regeneration occurs from the seed bank of the island, future vegetation will not move toward the original forest community, because the seed bank is dominated by non‐native herbaceous grassland species. Though isolated, a few forest remnants with low species richness could be an important source for the natural re‐establishment of forest on the island; however, seed availability may be limited by either poor dispersal or pollination so that woody species will probably recover very slowly on this goat‐impacted island.
Surgery and radiotherapy: complementary tools in the management of benign intracranial tumors
Authors: Johnson Walter D. , Loredo Lilia N. , Slater Jerry D.
Published: April 2008

✓ Historically, radiation therapy has been used extensively in the treatment of malignant and aggressive intracranial tumors, and the importance of its role has been repeatedly verified by prolonged patient survival rates and increased tumor control. As more modern capabilities are employed in surgery and radiotherapy, attention is being directed to the utility of radiation as either primary or secondary treatment of benign tumors. Specifically, primary treatment encompasses irradiation of small benign tumors without biopsy confirmation of tumor type; secondary treatment involves postoperative radiation therapy, with the possibility that less-aggressive tumor resection may be performed in areas that have a higher probability of resultant neurological deficit. Current literature suggests that this is not only a possible treatment strategy, but that it may be superior to more radical resection in some cases, for example, in vestibular schwannomas and meningiomas. This article provides an overview of factors to consider in the use of radiation therapy and reviews the relationships between radiation and surgery, notably the unique complementary role each plays in the treatment of benign intracranial tumors.
Use of trans sodium crocetinate for sensitizing glioblastoma multiforme to radiation
Authors: Sheehan Jason , Ionescu Adina , Pouratian Nader , Hamilton D. Kojo , Schlesinger David , Oskouian Rod J. , Sansur Charles
Published: April 2008

Object

Adjuvant treatment with radiation (radiation therapy or radiosurgery) is a mainstay of treatment for patients harboring glioblastomas multiforme (GBM). Hypoxic regions within the tumor make cells less sensitive to radiation therapy. Trans sodium crocetinate (TSC) has been shown to increase oxygen diffusion in the brain and elevate the partial brain oxygen level. The goal of this study was to evaluate the radiosensitizing effects of TSC on GBM tumors.

Methods

A rat C6 glioma model was used, in which C6 glioma cells were stereotactically injected into the rat brain to create a tumor. Following creation of a right frontal tumor, animals were randomized into 1 of 4 groups: 1) TSC alone (animal treated with moderate-dose TSC only); 2) radiation (animals receiving 8 Gy of cranial radiation); 3) radiation and low-dose TSC (animals receiving 8 Gy of radiation and 50 μg/kg of TSC); or 4) radiation and moderate-dose TSC (animals receiving 8 Gy of radiation and 100 μg/kg of TSC). Animals were observed clinically for 60 days or until death. Magnetic resonance (MR) imaging was performed at 2-week intervals on each animal and quantitatively evaluated for tumor response. Immunohistochemical analysis was performed on all brain tumors. Survival differences were also evaluated using the Kaplan–Meier method.

Results

On MR imaging, a statistically significant reduction in tumor size was seen in the group receiving moderate-dose TSC and radiation treatment compared with the group receiving radiation treatment alone. The rate of tumor growth was significantly less for the combination of TSC and radiation treatment compared with either modality alone. Median survival times for the TSC-only and the radiation therapy–only groups were 15 and 30 days, respectively. The 60-day median survival times for the groups receiving a combination of either low- or moderate-dose TSC with radiation therapy were statistically improved compared with those for the other treatment groups.

Conclusions

Use of TSC improves the extent of GBM tumor regression following radiation therapy and enhances survival. Radiosensitization of hypoxic tumors through increased oxygen diffusion may have clinical utility in patients with GBM tumors but must be explored in a clinical trial.
Biomechanical study of cervical flexion myelopathy using a three-dimensional finite element method
Authors: Kato Yoshihiko , Kataoka Hideo , Ichihara Kazuhiko , Imajo Yasuaki , Kojima Takanori , Kawano Shunichi , Hamanaka Daisuke , Yaji Kentaro , Taguchi Toshihiko
Published: April 2008

Object

The goal of this study was to perform a biomechanical study of cervical flexion myelopathy (CFM) using a finite element method.

Methods

A 3D finite element model of the spinal cord was established consisting of gray matter, white matter, and pia mater. After the application of semi-static compression, the model underwent anterior flexion to simulate CFM. The flexion angles used were 5° and 10°, and stress distributions inside the spinal cord were then evaluated.

Results

Stresses on the spinal cord were very low under semi-static compression but increased after 5° of flexion was applied. Stresses were concentrated in the gray matter, especially the anterior and posterior horns. The stresses became much higher after application of 10° of flexion and were observed in the gray matter, posterior funiculus, and a portion of the lateral funiculus.

Conclusions

The 5° model was considered to represent the mild type of CFM. This type corresponds to the cases described in the original report by Hirayama and colleagues. The main symptom of this type of CFM is muscle atrophy and weakness caused by the lesion of the anterior horn. The 10° model was considered to represent a severe type of CFM and was associated with lesions in the posterior fand lateral funiculi. This type of CFM corresponds to the more recently reported clinical cases with combined long tract signs and sensory disturbance.
LOGIT ANALYSIS OF GENETIC DATA
Authors: Židanavičiutė J.
Published: April 2008

A new framework of genetic sequence statistical analysis based on generalized logit model is introduced. Logit analysis is applied to assess the dependence structure (interactions) between DNA nucleotides and to test hypothesis about Markov order of these dependencies. The procedure proposed seeks the non‐coding subsequences which are homogeneous but yet non‐Markov. It has been shown, that even homogeneous DNA regions can not be treated as the first order Markov sequences.
Solar steam reforming of natural gas for hydrogen production using molten salt heat carriers
Authors: Giaconia Alberto , de Falco Marcello , Caputo Giampaolo , Grena Roberto , Tarquini Pietro , Marrelli Luigi
Published: April 2008

The utilization of concentrated solar energy as external heat source for methane steam reforming has been investigated. Molten salts at temperatures up to 550°C can be used as solar heat carrier and storage system, and hydrogen selective membranes can be used to drive reforming reaction at lower temperatures than conventional (<550°C), with hydrogen purification achieved thereby. The combination of new technologies such as membranes and membrane reactors, concentrating solar power (CSP) systems, and molten salt heat carriers, allows a partial decarbonation of the fossil fuel together with the possibility to carry solar energy in the current natural gas grid. Different plant configurations and operating conditions have been analyzed using a mathematical model and AspenPlus simulator. © 2008 American Institute of Chemical Engineers AIChE J, 2008
Heritability of fluctuating asymmetry in a human twin sample: The effect of trait aggregation
Authors: Johnson Wendy , Gangestad Steven W. , Segal Nancy L. , Bouchard Thomas J.
Published: April 2008

Fluctuating asymmetry is thought to reflect developmental instability, which may in turn indicate genetically influenced fitness. Controversy surrounding these claims has centered on the extent to which fluctuating asymmetry is heritable. Most studies have estimated its heritability to be very low using single‐trait measures. This study uses data from a human twin sample to demonstrate that the heritability estimate resulting from the aggregation of fluctuating asymmetry across multiple traits is non‐zero. This is the case even when the estimates of fluctuating asymmetries of the individual traits do not differ significantly from 0. Am. J. Hum. Biol., 2008. © 2008 Wiley‐Liss, Inc.
Clinical delineation of Giuffrè–Tsukahara syndrome: Another case with microcephaly and radio‐ulnar synostosis with apparent X‐linked semi‐dominant inheritance
Authors: Gaspar Harald , Albermann Kurt , Baumer Alessandra , Schinzel Albert
Published: April 2008

Two families and three sporadic cases have been described so far with the combination of radio‐ulnar synostosis and microcephaly as main features. Some authors have discussed whether the first family reported by Giuffrè et al. [1994] and the second family described by Tsukahara et al. [1995] had the same syndrome. Although there is phenotypic variability among the described cases (especially with respect to facial dysmorphisms and mental retardation), the clinical patterns do not seem to be clearly distinguishable from each other. We describe another family with apparent X‐linked semi‐dominant inheritance with milder features in the female patient due to skewed X‐inactivation. From a clinical synopsis, we consider the Giuffrè–Tsukahara syndrome as one genetic entity, which is characterized by the association of microcephaly and radio‐ulnar synostosis, mental retardation in male patients and variable minor features. Patients with the Giuffrè–Tsukahara syndrome do not present with a characteristic pattern of facial features. © 2008 Wiley‐Liss, Inc.
Cryptic 17q22 deletion in a boy with a t(10;17)(p15.3;q22) translocation, multiple synostosis syndrome 1, and hypogonadotropic hypogonadism
Authors: Shimizu Reiko , Mitsui Norimasa , Mori Yasuhiro , Cho Shogen , Yamamori Shunji , Osawa Makiko , Ohashi Hirofumi
Published: April 2008

We report on a boy who had multiple synostosis syndrome 1, an autosomal dominant disorder characterized by progressive symphalangism, multiple joint fusions, conductive deafness, and mild facial dysmorphism. In addition the boy developed delay of puberty, bone age, and closure of the epiphyseal lines of long bones with tall stature. These findings and decreased plasma LH and FSH levels at age 19 years were compatible with hypogonadotropic hypogonadism. G‐banded chromosomes showed a balanced translocation t(10;17)(p15.3;q22). Chromosomal FISH analysis, using a series of BAC clones surrounding the translocation breakpoints, detected a 2.2–3.9 Mb deletion at 17q22. The deletion encompassed NOG, a gene responsible for multiple synostosis syndrome 1. It was assumed that a gene for pituitary secretion of gonoadotropic hormones was deleted at the 17q22 segment. © 2008 Wiley‐Liss, Inc.
Association study of the estrogen receptor alpha gene (ESR1) and childhood‐onset mood disorders
Authors: Mill Jonathan , Kiss Eniko , Baji Ildiko , Kapornai Krisztina , Daróczy Gabriella , Vetró Ágnes , Kennedy James , Kovacs Maria , Barr Cathy
Published: April 2008

Depressive disorders are heterogeneous psychiatric disorders involving deficits in cognitive, psychomotor, and emotional processing. Depressive disorders have a significant genetic component, with severe, recurrent and early‐onset forms demonstrating elevated heritability. In this study we genotyped eleven single nucleotide polymorphisms (SNPs) spanning the estrogen receptor alpha gene (ESR1) in a large family‐based childhood‐onset mood disorder (COMD) sample. None of the individual SNP or global haplotype analyses was significant in the entire COMD sample, but haplotype analysis of three SNPs in strong linkage disequilibrium (rs746432, rs2077647, and rs532010) uncovered an association with COMD, specifically in females. Our data are consistent with previous studies demonstrating a female‐specific association between ESR1 and neurobehavioral phenotypes. These results suggest the existence of sex‐specific etiological factors in depressive disorders, related to estrogen, with onset in childhood. © 2008 Wiley‐Liss, Inc.
The validity of the family history screen for assessing family history of mental disorders
Authors: Milne B.J. , Caspi A. , Crump R. , Poulton R. , Rutter M. , Sears M.R. , Moffitt T.E.
Published: April 2008

There is a need to collect psychiatric family history information quickly and economically (e.g., for genome‐wide studies and primary care practice). We sought to evaluate the validity of family history reports using a brief screening instrument, the Family History Screen (FHS). We assessed the validity of parents' reports of seven psychiatric disorders in their adult children probands from the Dunedin Study (n = 959, 52% male), using the proband's diagnosis as the criterion outcome. We also investigated whether there were informant characteristics that enhanced accuracy of reporting or were associated with reporting biases. Using reports from multiple informants, we obtained sensitivities ranging from 31.7% (alcohol dependence) to 60.0% (conduct disorder) and specificities ranging from 76.0% (major depressive episode) to 97.1% (suicide attempt). There was little evidence that any informant characteristics enhanced accuracy of reporting. However, three reporting biases were found: the probability of reporting disorder in the proband was greater for informants with versus without a disorder, for female versus male informants, and for younger versus older informants. We conclude that the FHS is as valid as other family history instruments (e.g., the FH‐RDC, FISC), and its brief administration time makes it a cost‐effective method for collecting family history data. To avoid biasing results, researchers who aim to compare groups in terms of their family history should ensure that the informants reporting on these groups do not differ in terms of age, sex or personal history of disorder. © 2008 Wiley‐Liss, Inc.
Lack of association between DRD3 gene polymorphism and response to clozapine in Turkish schizoprenia patients
Authors: Barlas I. Omer , Cetin Mesut , Erdal M. Emin , Semiz Umit B. , Basoglu Cengiz , Ay M. Ertan , Herken Hasan , Uzun Ozcan
Published: April 2008

It is hypothesized that molecular components of dopaminergic system, especially the dopamine D3 receptor gene (DRD3), may play a crucial role in the pathophysiology of schizophrenia, because it is abundant in the limbic system of the brain and it binds antipsychotic drugs. Several groups attempted to find an association between a serine‐to‐glycine polymorphism of the DRD3 gene (Ser9Gly) and schizophrenia; however, the results were inconsistent. In this study, we aimed to investigate the relationship of the Serine/Glycine polymorphism of the DRD3 gene with therapeutic response to clozapine treatment between Turkish schizophrenia patients (N = 92) and healthy controls (N = 100). Genotype groups were comparable in BPRS, SAPS, SANS analysis of response to clozapine. Our results suggest that an association between the Ser/Gly polymorphism of DRD3 gene and response to clozapine in Turkish schizophrenia patients is unlikely to exist. © 2008 Wiley‐Liss, Inc.
Association study between the genetic polymorphisms of glutathione‐related enzymes and schizophrenia in a Japanese population
Authors: Matsuzawa Daisuke , Hashimoto Kenji , Hashimoto Tasuku , Shimizu Eiji , Watanabe Hiroyuki , Fujita Yuko , Iyo Masaomi
Published: April 2008

Several lines of evidence suggest that oxidative stress plays a role in the pathogenesis of schizophrenia, and that glutathione (GSH) plays a crucial role in antioxidant defense mechanisms. In this study, we performed association studies between GSH‐related genes (GSTM1, GSTP1, GSTO1, GSTT1, GSTT2, GPX1, and GCLM) and schizophrenia in a Japanese population. The overall distributions of the genotypes and alleles of each gene were not different between schizophrenic patients and controls. Subjects with residual‐type schizophrenia showed different distributions in the analysis of GSTM1 genotype and in the combination analysis of GSTs, GPX1, and GCLM genotypes although the small sample size should be considered as a limitation of this study. In addition, our findings revealed that there were large ethnic differences in the genotype distributions of those GSH‐related genes. The present study suggests that GSH‐related genes may not play a major role in the pathogenesis of schizophrenia in a Japanese population. However, a dysregulation of GSH metabolism may be one of the vulnerability factors contributing to the development of a certain type of schizophrenia, and it is likely that the ethnic background should be considered in further study for those GSH‐related genes. © 2008 Wiley‐Liss, Inc.
The influence of age on fecal steroid hormone levels in male Budongo Forest chimpanzees (Pan troglodytes schweinfurthii)
Authors: Seraphin S.B. , Whitten P.L. , Reynolds V.
Published: April 2008

Potential interactions between age and endocrinological functioning have been understudied in wild ape populations. Therefore, we examined the relationship between age and the secretion of androgens and glucocorticoids in 15 juvenile, subadult, and adult male chimpanzees (Pan troglodytes schweinfurthii) free ranging in the Budongo Forest of Uganda. One hundred and nine fecal samples were opportunistically collected, between 07:30 and 13:30 hr, during the wet season. Fecal samples were preserved, by oven drying, and steroid content extracted before radioimmunoassay for dehydroepiandrosterone‐sulfate (DHEA‐S), testosterone (TEST), cortisol (CORT), and corticosterone (CCT). Employing indexes of age as predictive factors, linear mixed‐effects modeling and non‐parametric statistical comparisons of fecal steroid levels were conducted. Age was observed to significantly influence the production of both glucocorticoids and androgens in male Budongo Forest chimpanzees. Basically, whereas TEST and CORT increased, DHEA‐S and CCT levels slightly declined as animals matured. Am. J. Primatol. 70:661–669, 2008. © 2008 Wiley‐Liss, Inc.
Synthesis and characterization of biodegradable poly(butylene succinate‐co‐propylene succinate)s
Authors: Xu Yongxiang , Xu Jun , Liu Dehua , Guo Baohua , Xie Xuming
Published: April 2008

Biodegradable polyesters such as poly(butylene succinate) (PBS), poly(propylene succinate) (PPS), and poly(butylene succinate‐co‐propylene succinate)s (PBSPSs) were synthesized respectively, from 1,4‐succinic acid with 1,4‐butanediol and 1,3‐propanediol through a two‐step process of esterification and polycondensation in this article. The composition and physical properties of both homopolyesters and copolyesters were investigated via 1H NMR, DSC, TGA, POM, AFM, and WAXD. The copolymer composition was in good agreement with that expected from the feed composition of the reactants. The melting temperature (Tm), crystallization temperature (Tc), crystallinity (X), and thermal decomposition temperature (Td) of these polyesters decreased gradually as the content of propylene succinate unit increased. PBSPS copolyesters showed the same crystal structure as the PBS homopolyester. Besides the normal extinction crosses under the polarizing optical microscope, the double‐banded extinction patterns with periodic distance along the radial direction were also observed in the spherulites of PBS and PBSPS. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Effect of glycol and filler types on some polymeric composite properties
Authors: Asaad J. N. , Abd‐El‐Messieh S. L.
Published: April 2008

Two unsaturated polyesters based on maleic anhydride, phthalic anhydride, and sebasic acid with each of linear 1,6‐hexanediol (PEL) and cyclic 1,4‐cyclohexanediol (PEC) were prepared. Their structures were characterized by IR and 1H NMR spectra. Their composites were prepared by mixing different ratios (60, 70, and 80%) with talc and kaolin with polyester/styrene mixture. The effect of linear and cyclic glycols and the effect of filler type and concentration of these composites were studied in terms of their electrical properties and the hardness before and after aging. The thermal behavior of styrenated polyesters and their composites was studied using thermogravimetric analysis. It has been found that both fillers increase the thermal stability and decrease the weight loss. The permittivity ε′ and the dielectric loss ε″ were measured in the frequency range 100 Hz up to 100 kHz at room temperature 25°C ± 1. The polyester composite samples containing 70% filler lead to good electrical properties in addition to its resistance to thermal aging. The hardness value was increased by increasing the filler content before and after aging. The polyester composites based on cyclic glycol and loaded with 80% kaolin gave the highest hardness values. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Flame retardancy of hollow glass microsphere/rigid polyurethane foams in the presence of expandable graphite
Authors: Bian Xiang‐Cheng , Tang Jian‐Hua , Li Zhong‐Ming
Published: April 2008

Rigid polyurethane foams (RPUF) filled with various loadings of expandable graphite (EG) or/and hollow glass microspheres (HGM) were prepared by cast molding. The flame retardant properties of these composites were investigated by limiting oxygen index (LOI), horizontal and vertical burning tests. The composite with 10 wt % HGM and 20 wt % EG had the best flame retardant properties, and its LOI value reached 30 vol %. The addition of an appropriate loading of HGM improved the compressive strength and modulus of RPUF and EG/RPUF. When the HGM content arrived at 10 wt %, the compressive strength and modulus of the composites reached the maximum value. The dynamical mechanical analysis (DMA) showed that the addition of EG and HGM made the glass transition temperature shift to a higher temperature, and 10 wt % EG and 10 wt % HGM filled RPUF had the highest storage modulus. The scanning electronic microscope (SEM) observation indicates that the additives led to the decrease in the cell size. In addition, the flame retardant mechanism, the thermal properties, the burned surfaces and the interface surfaces were elucidated. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Antifoaming performance of polysiloxanes modified with fluoroalkyls and polyethers
Authors: Wu Fei , Cai Chun , Yi Wen‐Bin , Cao Zhi‐Ping , Wang Yun
Published: April 2008

A series of polysiloxanes modified with fluoroalkyls and polyethers were synthesized. Antifoaming performance of such modified polysiloxanes in the mixture of diesel and mobile fuel was studied. The effects of factors such as polyethers type, molar ratio between polyether and fluoroalkyl, hydrogen‐contents and viscosity of polysiloxanes, length of fluoroalkyls, etc., on the performance of modified products were discussed. It shows that polysiloxane modified with allyl polyoxypropylene ether and hexafluorobutyl acrylate has better breaking and inhibiting foam performance, when compared with that replacing allyl polyoxypropylene ether with allyl polyoxyethylene polyoxypropylene block ether and allyl polyoxyethylene ether. And when the molar ratio between allyl polyoxypropylene ether and hexafluorobutyl acrylate is 3 : 7, modified polysloxane has the best foam controlling performance. Low viscosity polysiloxane or low hydrogen content polysiloxane modified with allyl polyoxypropylene ether and hexafluorobutyl acrylate has better foam controlling performance. Polysiloxane modified with longer carbon chain fluoroalkyl and allyl polyoxypropylene ether has better antifoaming performance than that modified with shorter carbon chain fluoroalkyl and polyether and lower surface tension. The change of surface tension of foaming liquid between initially added with modified polysiloxane and after testing antifoaming performance was studied, and it shows that after testing performance of antifoam, the surface tension of foaming liquid becomes bigger which is one possible reason for antifoam exhausting. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Synthesis, extraction, and adsorption properties of calix[4]arene‐poly(ethylene‐glycol) crosslinked polymer
Authors: Zhu Weipu , Gou Pengfei , Zhu Kui , Shen Zhiquan
Published: April 2008

Novel calix[4]arene‐poly(ethylene glycol) crosslinked polymer (CCP) has been synthesized by the polycondensation reaction between a p‐tert‐butylcalix[4]arene derivative and dihydroxyl capped poly(ethylene glycol) (DHPEG, Mn = 1000) catalyzed by neodymium tosylate. The hydrogel, consisted of 66.9% water and 33.1% CCP, can selectively extract aromatic organic molecules from aqueous solution according to the diameter of the guest molecules, which infers that the diameter of the calix[4]arene cavity is about 5.4 Å and the conformation of calix[4]arene units altered from cone conformation to 1,3‐alternate conformation during the polycondensation reaction. Furthermore, CCP can also adsorb naphthalene from gas phase, showing much higher capacity than active carbon does, which may have some potential applications in the field of separation and environment protection. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Studies on preparation and properties of porous biodegradable poly(NIPAAm) hydrogels
Authors: Lee Wen‐Fu , Cheng Tzu‐Shen
Published: April 2008

A series of biodegradable porous hydrogels, based on thermosensitive N‐isopropylacrylamide (NIPAAm) and biodegradable crosslinker‐polycaprolactone diacrylate (PCLdA) that was synthesized from polycaprolactone diol with acryloyl chloride were prepared by photopolymerization at low temperature. The effect of the crosslinker content and gelation method on the swelling behaviors and physical properties for the poly(NIPAAm) hydrogels was investigated. Results showed that the swelling ratio of the gel in deionized water decreased with an increase of the content of polycaprolactone (PCL) segment in the poly(NIPAAm) hydrogels. The properties of the gels crosslinked with PCLdA were compared with those crosslinked with N, N′‐methylenebisacrylamide (NMBA). The results showed that the critical gel transition temperatures (CGTT) of the gels crosslinked with PCLdA were lower than those of the gels crosslinked with NMBA due to the hydrophobicity of the PCL segment. The results also showed that the gels crosslinked with PCLdA had higher mechanical strength and crosslinking density than those gels crosslinked with NMBA. Comparing the porous gels with nonporous gels, the results showed that the swelling ratio and CGTT of the porous gels were higher than those of the nonporous gels, and the transition temperature curve was smoother for the porous gels. The porous gels also exhibited more rapid thermal response and faster degradation rates. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Effects of Temperature Regime Through Premetamorphic Ontogeny on Shape of the Chondrocranium in the American Toad, Anaxyrus americanus
Authors: Jorgensen Michael E. , Sheil Christopher A.
Published: April 2008

If one considers the substantial amount of information that exists about phenotypic plasticity in amphibians, it is surprising that few studies have examined abiotic factors that influence phenotype through ontogeny. Phenotypic change and stability of morphology are artifacts of organisms that bear significant relevance to evolution within and among taxonomic groups. Here, we examine development as a phenotypically plastic aspect of larval anurans. Fertilized eggs of the American Toad, Anaxyrus (= Bufo) americanus (Holbrook, 1836), were obtained from two pairs of adults, and larvae were reared in four temperature treatments (constant Mean, constant High, constant Low, and Fluctuating regime [Low night–High day]); developmental series were collected from each treatment, representing larvae of this species from Gosner Stages 28–40. Cleared and stained larvae were analyzed with landmark‐based geometric morphometric methods to facilitate examination of differences in overall shape change of the larval chondrocranium through ontogeny, as a result of developmental temperature or temperature regime. Changes in shape of the chondrocranium and in amount and direction of phenotypic change through ontogeny were found in response to temperature treatment and temperature regime. Mean chondrocranial shape of the Fluctuating regime was more similar to the consensus shape of the overall data set than were those of all other treatments. Given that differences in amount and direction of shape change were observed among these treatments and throughout ontogeny, one should consider the affects of abiotic factors (such as temperature) when rearing larval anurans for studies of developmental morphology. Anat Rec, 291:818‐826, 2008. © 2008 Wiley‐Liss, Inc.
Heteropterys aphrodisiaca Infusion Reduces the Collateral Effects of Cyclosporine A on the Testis
Authors: Monteiro Juliana C. , Predes Fabrícia S. , Matta Sérgio L.P. , Dolder Heidi
Published: April 2008

Cyclosporine A (CsA) is known to have testicular toxicity, leading to male infertility. Stimulant and aphrodisiac properties have been attributed to the plant, Heteropterys aphrodisiaca. Thus, the present work was undertaken to evaluate the association of the drug and the medicinal herb in Wistar rats, applying testicular morphometry and ultrastructure. Twenty‐four rats were used, divided into four groups: I, control; II, CsA; III, simultaneous use of CsA and H. aphrodisiaca; IV, H. aphrodisiaca. Daily administration by gavage was carried out, during 56 days, of water (sham), CsA in a dose of 15 mg/kg per day and/or H. aphrodisiaca in a dose of 0.5 ml of the infusion prepared with 25 g of roots/100 ml of boiling water. Increased body weight was observed for all groups, but the animals that received only CsA showed the smallest body weight gain. Morphometry showed increased connective tissue volumetric proportion and decreased Leydig cell volumetric proportion in CsA‐treated rats. Using transmission electron microscopy, it was possible to ascertain that CsA caused seminiferous epithelium degeneration, resulting in Sertoli cell vacuolization, abnormal round and elongated spermatids and large accumulation of residual cytoplasm at the epithelium border next to the lumen. Expanded intercellular spaces between germ cells were still observed in H. aphrodisiaca‐treated rat testes. The administration of H. aphrodisiaca infusion to CsA‐treated rats diminished nearly all the CsA‐induced damage to the testis ultrastructure, suggesting that H. aphrodisiaca infusion may be used combined with CsA to reduce CsA‐induced injuries in the testis. Anat Rec, 291:809‐817, 2008. © 2008 Wiley‐Liss, Inc.
Hybridization‐Sensitive On–Off DNA Probe: Application of the Exciton Coupling Effect to Effective Fluorescence Quenching
Authors: Ikeda Shuji , Okamoto Akimitsu
Published: April 2008

The design of dyes that emit fluorescence only when they recognize the target molecule, that is, chemistry for the effective quenching of free dyes, must play a significant role in the development of the next generation of functional fluorescent dyes. On the basis of this concept, we designed a doubly fluorescence‐labeled nucleoside. Two thiazole orange dyes were covalently linked to a single nucleotide in a DNA probe. An absorption band at approximately 480 nm appeared strongly when the probe was in a single‐stranded state, whereas an absorption band at approximately 510 nm became predominant when the probe was hybridized with the complementary strand. The shift in the absorption bands shows the existence of an excitonic interaction caused by the formation of an H aggregate between dyes, and as a result, emission from the probe before hybridization was suppressed. Dissociation of aggregates by hybridization with the complementary strand resulted in the disruption of the excitonic interaction and strong emission from the hybrid. This clear change in fluorescence intensity that is dependent on hybridization is useful for visible gene analysis.
Error‐correction methods and evaluation of an ensemble based hydrological forecasting system for the Upper Danube catchment
Authors: Bogner K. , Kalas M.
Published: April 2008

Within the EU Project PREVention, Information and Early Warning (PREVIEW), ensembles of discharge series have been generated for the Danube catchment by the use of various weather forecast products. Hydrological models applied for streamflow prediction often have simulation errors that degrade forecast quality and limit the operational usefulness of the forecasts. Therefore, error‐correction methods have been tested for adjusting the ensemble traces using a transformation derived with simulated and observed flows. This article presents first results of the combination of state‐space models and wavelet transformations in order to update errors between the simulated (forecasted) and the observed discharge. Copyright © 2008 Royal Meteorological Society
Mitochondria and ageing in Drosophila
Authors: Morrow Geneviève , Tanguay Robert M.
Published: April 2008

Studies in different organisms have revealed that ageing is a complex process involving a tight regulation of gene expression. Among other features, ageing organisms generally display an increased oxidative stress and a decreased mitochondrial function. The increase in oxidative stress can be attributable to reactive oxygen species, which are mainly produced by mitochondria as a by‐product of energy metabolism. Consistent with these data, mitochondria have been suggested to play a significant role in lifespan determination. The fruitfly Drosophila melanogaster is a well‐suited organism to study ageing as it is relatively short‐lived, mainly composed of post‐mitotic cells, has sequenced nuclear and mitochondrial genomes, and multiple genetic tools are available. It has been used in genome‐wide studies to unveil the molecular signature of ageing, in different feeding and dietary restriction protocols and in overexpression and down‐regulation studies to examine the effect of specific compounds or genes/proteins on lifespan. Here we review the various features linking mitochondria and ageing in Drosophila melanogaster.
High levels of stable phytase accumulate in the culture medium of transgenic Medicago truncatula cell suspension cultures
Authors: Pires Ana Sofia , Cabral M. Guadalupe , Fevereiro Pedro , Stoger Eva , Abranches Rita
Published: April 2008

The use of plants for production of recombinant proteins is becoming widely accepted. More recently, plant cell cultures have been proposed as valuable systems for producing a wide range of biologically active proteins. Such systems provide certain advantages over whole plants, but yields are still considered a limitation. In this study we established a Medicago truncatula cell suspension line expressing phytase from Aspergillus niger. Phytase is an N‐glycosylated enzyme that breaks down indigestible phytate, resulting in an increased availability of phosphorus and other minerals in monogastric animals and reduced levels of phosphorus output in their manure. Various production systems have previously been used to express heterologous phytase, including several plant species. In this work, remarkable amounts of enzymatically active recombinant phytase were produced and secreted into the culture medium. Recombinant phytase accumulated to at least 25 mg/L and remained stable along the growth curve, and an enriched fraction with high enzymatic activity was easily obtained. We therefore propose M. truncatula cell suspension cultures as a potential system for the production of recombinant proteins. Most importantly, we have shown that, contrary to general belief, it is possible to achieve high levels of a functional recombinant protein in plant cell culture systems.
Torsional Angular Dependence of 1J(Se,Se) and Fermi Contact Control of 4J(Se,Se): Analysis of nJ(Se,Se) (n=1–4) Based on Molecular Orbital Theory
Authors: Nakanishi Waro , Hayashi Satoko
Published: April 2008

nJ(Se,Se) (n=1–4) nuclear couplings between Se atoms were analyzed by using molecular orbital (MO) theory as the first step to investigating the nature of bonded and nonbonded nJ(Se,Se) interactions between Se atoms. The values were calculated by employing Slater‐type triple ξ basis sets at the DFT level, which were applied to structures optimized with the Gaussian 03 program. The contribution from each occupied MO (ψi) and ψi→ψa (ψa=unoccupied MO) transition was evaluated separately. 1J(Se,Se) was calculated for the MeSeSeMe model compound, which showed a typical dependence on the torsion angle (ϕ(CMeSeSeCMe)). This dependence explains the small values (≤64 Hz) of 1Jobsd(Se,Se) observed for RSeSeR′ and large values (330–380 Hz) of 1Jobsd(Se,Se) observed for 4‐substituted naphtho[1,8‐c,d]‐1,2‐diselenoles, which correspond to synperiplanar diselenides. The HOMO→LUMO and HOMO−1→LUMO transitions contribute the most to 1J(Se,Se) at ϕ=0 and 180° to give large values of 1J(Se,Se), whereas various transitions contribute and cancel each other out at ϕ=90° to give small values of 1J(Se,Se). Large 4Jobsd(Se,Se) values were also observed in the nonbonded Se⋅⋅⋅Se, Se⋅⋅⋅SeO, and OSe⋅⋅⋅SeO interactions at naphthalene 1,8‐positions. The Fermi contact (FC) term contributes significantly to 4J(Se,Se), whereas the paramagnetic spin‐orbit (PSO) term contributes significantly to 1J(Se,Se). 2J(Se,Se) and 3J(Se,Se) were analyzed in a similar manner and a torsional angular dependence was confirmed for 3J(Se,Se). Depending on the structure, the main contribution to nJ(Se,Se) (n=2, 3) is from the FC term, with a lesser contribution from the PSO term. Analysis of each transition enabled us to identify and clearly visualize the origin and mechanism of the couplings.
Supramolecular Polymerization and Polymorphs of Oligo(p‐phenylene vinylene)‐Functionalized Bis‐ and Monoureas
Authors: Yagai Shiki , Kubota Shun , Iwashima Tomoyuki , Kishikawa Keiki , Nakanishi Takashi , Karatsu Takashi , Kitamura Akihide
Published: April 2008

Bis‐ and monoureas hybridized with the oligo(p‐phenylene vinylene) (OPV) π‐electronic segment and 3,4,5‐tridodecyloxyphenyl wedge were synthesized and their supramolecular polymerization in diluted solution, gel formation in concentrated solution, and liquid crystallinity in bulk state were investigated. Bisurea 1 a featuring a hexamethylene linker showed the highest supramolecular polymerization ability and formed tapelike nanofibers that can gelate various organic solvents. On the other hand, bisurea 1 b featuring a dodecamethylene linker and monourea 2 showed a lower degree of supramolecular polymerization, resulting in gel formations in a smaller variety of solvents. These results clearly reflect a high level of cooperativity between the two urea sites and the two OPV segments of 1 a upon hydrogen‐bonding and π–π stacking interactions, respectively. When the gels of 1 a, 1 b, and 2 were dried, all the compounds self‐organized into multilamellar superstructures. Thermal treatment of these lamellae at high temperatures induces columnar liquid‐crystalline mesophases as a result of microsegregation between the rigid OPV parts and the molten aliphatic wedges. These results demonstrate that the present molecular constituent is very useful for fabricating dye‐based functional assemblies providing nanoscale π‐electronic fibers, and solvent‐incorporated and bulk soft materials.