bluuebunny/crossref_metadata_2025 huggingface dataset:
Surgical treatment of patients with initially inoperable and/or metastatic gastrointestinal stromal tumors (GIST) during therapy with imatinib mesylate
Authors: Rutkowski Piotr , Nowecki Zbigniew , Nyckowski Pawel , Dziewirski Wirginiusz , Grzesiakowska Urszula , Nasierowska‐Guttmejer Anna , Krawczyk Marek , Ruka Wlodzimierz
Published: February 2006

Background

The aim of the study was to analyze the surgical possibilities of unresectable and/or metastatic GIST CD117(+) patients during imatinib treatment.

Methods

We analyzed the results of surgery in 141 patients treated with imatinib for initially inoperable and/or metastatic GIST CD117(+). Median follow‐up time was 12 months (range: 3–26).

Results

Surgery was performed as subsequent treatment in 24 patients (Group I, 17%) for resection of residual disease after complete/partial response and lack of further response to imatinib and as salvage therapy in eight patients (Group II, 6%), who progressed on initially successful imatinib therapy. In Group I, the viable GIST cells were not detected histologically in only three resection specimens. The first five patients in Group I did not receive imatinib further and we observed four recurrences. In next 19 patients, continuing imatinib after surgery, we observed only one relapse. In Group II, we continued imatinib therapy after high‐risk surgical procedures, but in five patients we observed subsequent progression.

Conclusions

Surgical removal of residual disease during imatinib treatment may allow for complete remission in selected GIST patients after response to therapy, theoretically prolonging durable remission, but it is necessary to continue imatinib for its maintenance. J. Surg. Oncol. 2006;93:304–311. © 2006 Wiley‐Liss, Inc.
Modified intrapleural cisplatin treatment for lung cancer with positive pleural lavage cytology or malignant effusion
Authors: Muraoka Masashi , Oka Tadayuki , Akamine Shinji , Tagawa Tsutomu , Morinaga Masafumi , Inoue Masao , Yamayoshi Takatomo , Hashizume Satoshi , Matsumoto Keitaro , Hayashi Tomayoshi , Nagayasu Takeshi
Published: February 2006

Objectives

We evaluate the efficacy and safety of the modified intrapleural cisplatin treatment for lung cancer patients with positive pleural lavage cytology or malignant effusion.

Methods

The treatment was performed for seven patients with malignant effusion and 18 patents with positive pleural lavage cytology. After pulmonary resection, the pleural cavity was filled with cisplatin with a normal saline solution for 30 min. Complications and survival of the patients were evaluated.

Results

The chest tube duration were significantly prolonged in the treatment (CDDP) group (5.7 ± 3.6 vs. 2.8 ± 2.6 days). We had one operative death that developed a bronchial fistula; however, the other complications were not severe. The mortality rate was 4% and the morbidity rate was 60%. We experienced two carcinomatous pleuritis in the CDDP group. The median survival time of the CDDP group was 47.0 ± 11.1 months and the 3‐ and 5‐year survival rate was 52.6% and 11.3%, respectively.

Conclusions

We were able to perform this treatment for these advanced lung cancer patients, which had the preventive effect of carcinomatous pleuritis. This therapy shows the possibility of a treatment that might lead to an improvement in the prognosis of these patients, without causing severe complications. J. Surg. Oncol. 2006;93: 323–329. © 2006 Wiley‐Liss, Inc.
Feasibility of bisegmentectomy 7–8 is independent of the presence of a large inferior right hepatic vein
Authors: Machado Marcel Autran C. , Herman Paulo , Makdissi Fabio F. , Figueira Estela R.R. , Bacchella Telesforo , Machado Marcel C.C.
Published: February 2006

Background

Right superior liver resection or bisegmentectomy 7–8 is defined as the anatomical removal of segments 7 and 8 of the liver. According to recent reports, this type of resection requires the presence of a large accessory right inferior hepatic vein to drain the remaining segment 6. However, anatomic studies have shown that segment 6 has multiple veins presenting several anastomosis with the surrounding hepatic veins. Therefore, the maintenance of the veins from segment 5 that ultimately drain into the middle hepatic vein can be enough to assure venous drainage of both segments.

Methods

Describe an alternative technique for bisegmentectomy 7–8 using intrahepatic glissonian access in patients with absence of a large inferior right hepatic vein.

Results

The technique was successfully performed in four consecutive patients without immediate or long‐term venous or venous related complications.

Conclusions

Bisegmentectomy 7–8 may increase resectability rate in patients with bilateral lesions and may also enhance the opportunity to perform repeated resections in cases of tumor recurrence. Our study confirms the anatomical assumption that bisegmentectomy 7–8 did not result in segmental outflow block even in the absence of a thick inferior right hepatic vein and therefore should be performed more often than reported so far. The absence of this vein should not be a straightforward indication for right hepatectomy in cases where a liver‐sparing procedure such as bisegmentectomy 7–8 can be safely employed. J. Surg. Oncol. 2006;93: 338–342. © 2006 Wiley‐Liss, Inc.
Particle in short-range potential in two dimensional
structure in magnetic field
Authors: Andreev S P , Pavlova T V
Published: February 2006

An exact solution is given for the problem of
determining the ground state of a charge particle in a zero range
force field located in a quantum well and in a magnetic field. The
dependence of the electron's ground state on the potential depth
and the magnetic field is investigated in a semiconductor layer
of an arbitrary width. In particular, it is shown that in the
two-dimensional case the bound state exists in potential at the
definite relation between the scattering length, the magnetic
length, and the layer width, in contrast to the three-dimensional
case, where the bound state always exists in an arbitrary
potential in the magnetic field.
Dispersion and nonlinearity nanomanagement of highly nonlinear
photonic-crystal fibers for the spectral transformation of
Cr:forsterite laser pulses
Authors: Fedotov A B , Serebryannikov E E , Ivanov A A , Mel'nikov L A , Shcherbakov A V , Sidorov-Biryukov D A , Sun Ch-K , Alfimov M V , Zheltikov A M
Published: February 2006

Fabrication and experimental demonstration of
photonic-crystal fibers (PCFs) made of TF10 glass are reported.
These fibers integrate a high material nonlinearity with
dispersion and field-confinement nanomanagement. A specifically
designed array of nanoholes in the fiber core is shown to provide
the desired dispersion and nonlinearity properties of PCF modes,
allowing efficient frequency upconversion of Cr:forsterite laser
pulses through solitonic and four-wave mixing mechanisms.
Steady-state and transient thermal lens behavior in the dual
beam Z-scan arrangement
Authors: Lorenc D , Vojtek P
Published: February 2006

Output beam spatial properties of a dual wavelength CW
DPSS laser have been studied using the thermal lens (photothermal)
effect. In employing the Z-scan technique both the
steady-state and time-dependent thermal lens signal as a function
of sample position could be examined simultaneously. The influence
of sample thickness and laser output power upon obtained spatial
properties of incident beam is studied. It is shown, that both the
steady state and the transient photothermal signal provide
comparable results.
Transition rate dependence on the improved turning point in ADK-theory
Authors: Ristić V M , Stevanović J M , Radulović M M
Published: February 2006

Estimation of transition rate of ionization of atoms for short range potential, based on assumptions of Keldysh approximation, shows that short-range potential does not affect the energy of the final state of ejected electron, when it leaves the atom. Coulomb potential is then treated as perturbation of final state energy leading to the ADK-theory. But Coulomb interaction was not originally included in calculating the turning point. This we corrected in [1], though only for fields with intensities below those of the atomic field. But as the ADK-theory was recently extended to the case of superstrong fields, our calculations now include extension of potential range up to 1017W/cm2; this leads to the shift of position of the turning point τ, which then influences transition rates for atoms in the low-frequency electromagnetic field of superstrong lasers. On Figs. 1 and 2 obtained from our calculations the value ofZwas switched from 1 to 10 at field intensity of 5 × 1013W/cm2(atomic unit system), which is done for the first time ever. The second figure also indicates an enormous activity at fields 1013W/cm2, which is due to strong tunneling effect for this energies of laser field. After that, there is saturation at a very low level of transition rate for fields from 1015W/cm2to 1017W/cm2.
Conversion from tacrolimus to cyclosporine in liver transplanted patients with diabetes mellitus
Authors: Dumortier Jérôme , Bernard Sophie , Bouffard Yves , Boillot Olivier
Published: February 2006

Adverse effects associated with calcineurin inhibitors may impact their clinical utility in some patients. This study characterizes the clinical outcomes of liver transplanted (LT) patients who experienced diabetes mellitus (DM) on tacrolimus-based regimen and were converted to cyclosporine-based therapy. Since January 2002, all patients with DM on a tacrolimus-based regimen were recruited and converted to cyclosporine-based therapy, after a 6-month minimal follow-up after LT. Clinical and laboratory data related to the clinical course of the patients were recorded. Twenty-five patients were included after a median delay of 54 months after LT [seven women and 18 men, 51 years (range 30–69)]. There were 11 patients with insulin-treated DM (ITDM), 14 patients with noninsulin-treated DM (NITDM), and the glycemic control was poor (HbA1c > 6.5%) in 13/25 patients (52%). After a median follow-up of 20 months after conversion, there were four patients with ITDM, 17 patients with NITDM, and four patients without DM, and the glycemic control was poor in 3/25 patients (12%). Four patients returned to tacrolimus because of arterial hypertension or digestive side-effects. In conclusion, our results suggest that conversion from tacrolimus to cyclosporine in stable LT patients with DM is well tolerated and beneficial on glycemic control.
Liver Transpl 12:659–664, 2006.

© 2006 AASLD.
No association of primary adenocarcinomas of the small bowel with Epstein‐Barr virus infection
Authors: von Rahden Burkhard H.A. , Langner Cord , Brücher Björn L.D.M. , Stein Hubert J. , Sarbia Mario
Published: February 2006

Epstein‐Barr Virus (EBV) infection is considered to play an etiologic role in human malignancies, including a subset of gastric and cardiac cancers. Adenocarcinomas of the small bowel comprise a very rare entity, with little knowledge about molecular properties and etiological aspects. We have investigated the prevalence of EBER expression (EBV‐encoded small RNAs) in a series of small bowel adenocarcinomas (n = 56) utilizing RNA in situ hybridization (EBER‐RISH). The patients had undergone primary surgical resection at either the Technical University of Munich or at the University of Graz. A surgical series of 82 primary resected gastric (n = 36) or cardiac (n = 46) adenocarcinomas (TU Munich) was used as control group. None of the 56 small bowel carcinomas exhibited EBER expression whereas in the control group the rate of EBER expression accounted for 4.4% in the group of cardia carcinomas and 8.6% in the group of gastric cancers. These results indicate that EBV infection plays no etiologic role in primary small bowel adenocarcinomas. © 2006 Wiley‐Liss, Inc.
CEO compensation and the seasoned equity offering decision
Authors: F. Brazel Joseph , Webb Elizabeth
Published: February 2006

Empirical research on seasoned equity offerings indicates that the decision to make an SEO typically engenders a decline in firm value, as investors interpret this decision as a signal of poor financial health or that the stock is overpriced. Here, we add to the literature by analyzing the short‐term market reaction to SEO announcements and the chief executive officer's link to firm performance (i.e. the proportion of CEO equity‐based compensation). Results support the hypothesis that investors are more likely to view the announcement of an SEO as a last resort source of capital when the proportion of CEO equity‐based compensation is high. In such cases of high equity‐based compensation, our findings indicate that the SEO announcement provides an incremental signal of financial distress above that provided by financial statements. We also find this relationship (last resort signal) to be stronger when large information asymmetries exist between management and investors. Thus, managers should consider the ramifications of executive compensation structure when considering whether to make an SEO. Copyright © 2006 John Wiley & Sons, Ltd.
HIV‐1 integrase inhibitors: 2003–2004 update
Authors: Dayam Raveendra , Deng Jinxia , Neamati Nouri
Published: February 2006

The integration of viral cDNA into the host genome is an essential step in the HIV‐1‐life cycle and is mediated by the virally encoded enzyme, integrase (IN). Inhibition of this process provides an attractive strategy for antiviral drug design. The discovery of β‐diketo acid inhibitors played a major role in validating IN as a legitimate antiretroviral drug target. Over a decade of research, a plethora of IN inhibitors have been discovered and some showed antiviral activity consistent with their effect on IN. To date, at least two compounds have been tested in human but none are close to the FDA approval. In this review, we provide a comprehensive report of all small‐molecule IN inhibitors discovered during the years 2003 and 2004. Compilation of such data will prove beneficial in developing QSAR, virtual screening, pharmacophore hypothesis generation, and validation. © 2006 Wiley Periodicals, Inc. Med Res Rev
Surface mapping of binding of oviductin to the plasma membrane of golden hamster spermatozoa during in vitro capacitation and acrosome reaction
Authors: Kan Frederick W.K. , Esperanzate Patrick W.B.
Published: February 2006

Oviductins are high‐molecular‐weight glycoproteins synthesized and secreted by nonciliated oviductal epithelial cells and have been shown to play a role in fertilization and early embryo development. The present study was carried out to examine the in vitro binding capacity of hamster oviductin to homologous sperm and to determine the sites of its localization in untreated, capacitated, and acrosome‐reacted spermatozoa. Freshly prepared epididymal and capacitated sperm as well as acrosome‐reacted sperm were incubated with oviductal fluid prepared from isolated hamster oviducts, fixed and then probed with a monoclonal antibody against hamster oviductin. Results obtained with pre‐embedding immunolabeling experiments revealed binding of oviductin to the acrosomal cap and the apical aspect of the postacrosomal region. Immunolabeling of both regions appeared to be more intense in capacitated spermatozoa. Acrosome‐reacted sperm showed an immunoreaction of moderate intensity over the postacrosomal region. The plasma membrane overlying the equatorial segment also exhibited a weak labeling. Quantitative analysis obtained with the surface replica technique indicated that oviductin had a higher binding affinity for the acrosomal cap than the postacrosomal region and that the binding of oviductin to the latter plasma membrane domain was enhanced during capacitation. Binding of oviductin to the postacrosomal region, however, was attenuated after acrosome reaction. Immunolabeling for oviductin was found to be the weakest over the equatorial segment regardless of the experimental conditions. The binding of hamster oviductin to specific membrane domains of the homologous sperm and the changes in its distribution during capacitation and acrosome reaction may be important for the function of hamster oviductin preceding and during fertilization. Mol. Reprod. Dev. © 2006 Wiley‐Liss, Inc.
Effects of amino acid substitutions in and around the arginine‐glycine‐aspartic acid (RGD) sequence on fertilization and parthenogenetic development in mature bovine oocytes
Authors: Sessions B.R. , Aston K.I. , Davis A.P. , Pate B.J. , White K.L.
Published: February 2006

Integrins have been shown to be involved in the process of fertilization and many integrin–ligand interactions are mediated through the recognition of an arginine‐glycine‐aspartic acid (RGD) sequence. Despite the fact the RGD domain is a principal player in determining the functional characteristics of an adhesive protein, increasing evidence has accumulated implicating the amino acids flanking the RGD sequence in determining the functional properties of the RGD‐containing protein. A set of linear peptides in which the amino acid sequence in and around the RGD tri‐peptide was modified was synthesized to better understand the specificity of the RGD–receptor interaction. Mature oocytes were fertilized in vitro in the presence of RGD‐containing and RGD‐modified peptides. Both the RGD‐containing and RGD‐modified peptides impaired the ability of sperm to fertilize bovine oocytes, illustrated by a reduction in cleavage. The linear modified RGD containing peptides were also examined for their ability to induce parthenogenetic development with the objective of providing a linear RGD peptide with greater biological activity than the one (GRGDSPK) used previously (Campbell et al., 2000). The data demonstrate the specificity of the receptor for the RGD sequence, further implicate the involvement of integrins in the process of bovine fertilization, and illustrate the importance of the amino acids surrounding the RGD sequence in determining the binding and functional properties of RGD‐containing peptides. The data support the findings that a linear RGD peptide can block fertilization and that amino acids around the RGD sequence have an impact on the biological activity of the receptor. Mol. Reprod. Dev. © 2006 Wiley‐Liss, Inc.
Sympathetic skin responses in Type‐1 diabetic children: Relationship to urodynamic findings
Authors: Soylu Ahmet , Akinci Aysehan , Yilmaz Ugur , Sarier Mehmet , Aslan Mehmet , Ozcan Cemal
Published: February 2006

Aims

Cystopathy is an important problem in diabetes mellitus (DM) when diabetes is not well‐controlled. In most cases of diabetic csytopathy, autonomic involvement is responsible, which develops insidiously over a long time. We investigated the hand and genital sympathetic skin responses (SSRs) and its relation to urodynamic abnormalities in this group of patients.

Methods

We performed hand and genital SSRs in 24 children with Type‐1 DM, whose hemoglobin A1C values were above normal limits. We also recruited 19 healthy children for SSRs measurements. Cystometry was performed in 24 children with Type‐1 DM. Based on cystometry findings, these children were classified into two groups as normal (n:6) and abnormal (n:18). The amplitude and latency of hand and genital SSRs of 24 children with Type‐1 DM and 19 healthy children were compared.

Results

Hand and genital SSRs were obtained from all of the diabetic and healthy children. The mean genital SSRs amplitude in diabetic children was significantly lower than the controls. There was no difference in the mean values of all investigated parameters between the normal group and controls. When compared to the controls, there was prolonged latency and decreased amplitude of genital SSRs and decreased hand SSRs amplitude in abnormal group.

Conclusions

SSR is a non‐invasive test for the evaluation of autonomic sympathetic involvement. Our study revealed differences in genital SSR before the manifestations of cystopathy. Children with abnormal urodynamic findings had changes in both hand and genital SSRs. These findings suggest that SSR tests may have a place in the evaluation of diabetic cystopathy in the early asymptomatic period. Neurourol. Urodynam. 25:243–248, 2006. © 2006 Wiley‐Liss, Inc.
Coarse grid classification: a parallel coarsening scheme for algebraic multigrid methods
Authors: Griebel Michael , Metsch Bram , Oeltz Daniel , Schweitzer Marc Alexander
Published: February 2006

In this paper, we present a new approach to the parallelization of algebraic multigrid (AMG), i.e. to the parallel coarse‐grid selection in AMG. Our approach involves (almost) no special treatment of processor subdomain boundaries and hence avoids a number of drawbacks of other AMG parallelization techniques. The key idea is to select an appropriate (local) coarse grid on each processor from a set of admissible grids such that the composed coarse grid forms a suitable coarse grid for the whole domain, i.e. there is no need for a special boundary treatment. To this end, we first construct multiple equivalent coarse grids on each processor subdomain. In a second step we then select exactly one grid per processor by a graph clustering technique. The results of our numerical experiments clearly indicate that this approach results in coarse grids of high quality which are very close to those obtained with sequential AMG. Furthermore, the operator and grid complexities of our parallel AMG are mostly smaller than those obtained by other parallel AMG methods, whereas the scale‐up behaviour of the proposed algorithm is similar to that of other parallel AMG techniques. However a significant improvement with respect to the speed‐up performance is achieved. Copyright © 2006 John Wiley & Sons, Ltd.
PTHrP‐independent hypercalcemia with increased proinflammatory cytokines and bone resorption in two children with CD19‐negative precursor B acute lymphoblastic leukemia
Authors: Niizuma Hidetaka , Fujii Kunihiro , Sato Atsushi , Fujiwara Ikuma , Takeyama Junji , Imaizumi Masue
Published: February 2006

Hypercalcemia in childhood acute lymphoblastic leukemia (ALL) is rare and occasionally associated with parathyroid hormone‐related protein (PTHrP). However, the pathogenesis of PTHrP‐independent hypercalcemia remains unclear. We report two children with precursor B ALL who had marked hypercalcemia (15.8 and 16.6 mg/dl, respectively) and disseminated osteolysis. Serum tumor necrosis factor‐α (TNF‐α) and IL‐6 were markedly elevated, whereas 1,25(OH)2 vitamin D3, intact PTH and PTHrP were decreased or undetected. Analysis of urinary deoxypyridinoline (DPY) or bone biopsy of the osteolytic lesion showed an increased bone resorption, and administration of bisphosphonate improved the hypercalcemia. Patients had ALL with immunophenotype positive for CD10, CD34, and HLA‐DR but negative for CD19 and obtained remission with chemotherapy. These findings suggest that increased osteoclastic bone resorption via stimulation with TNF‐α and IL‐6 may be mechanism causing PTHrP‐independent hypercalcemia in some patients with precursor B ALL lacking CD19 expression. Pediatr Blood Cancer 2007;49:990–993. © 2006 Wiley‐Liss, Inc.
HLA association is different in children and adults with severe acquired aplastic anemia
Authors: Führer Monika , Durner Jürgen , Brünnler Günter , Götte Heiko , Deppner Cornelia , Bender‐Götze Christine , Albert Ekkehard
Published: February 2006

Background

Severe aplastic anemia (SAA) is defined as pancytopenia caused by bone marrow failure. The pathogenesis of SAA is thought to involve autoimmune processes. Increased susceptibility to autoimmunity has been shown to be associated with several different HLA alleles. In SAA, few large studies based on data mainly from adults describe a positive HLA correlation with HLA‐DR2 (DRB1*15) and HLA‐B14.

Procedure

This study explored the HLA constitution of 181 children with SAA who were enrolled in the prospective multi‐center study SAA94 between January 1994 and January 2002. The control group consisted of 303 healthy individuals of comparable demographic background. Allelic frequencies between patients and controls are compared using Fisher's exact test.

Results

In our pediatric cohort, we describe a positive association with HLA‐B14 (P = 0.0039), but no association of HLA‐DR2 with SAA.

Conclusion

HLA associations appear to be different in children and adults with SAA. This might point towards a difference in pathophysiology between at least part of the children and adults. Pediatr Blood Cancer 2007;48:186–191. © 2006 Wiley‐Liss, Inc.
Elevation of tricuspid regurgitant jet velocity, a marker for pulmonary hypertension in children with sickle cell disease
Authors: Ambrusko Steven J. , Gunawardena Sriya , Sakara Allison , Windsor Beth , Lanford Lizabeth , Michelson Peter , Krishnamurti Lakshmanan
Published: February 2006

Background

Pulmonary hypertension (PHTN) is a potentially life‐threatening complication, detected by echocardiographic evidence of elevated tricuspid regurgitant velocity (TRV). This condition has been described in adults with sickle cell disease (SCD) and other hemolytic disorders; however, there is little information on the occurrence of this condition in pediatric patients.

Methods

Records for pediatric SCD patients were retrospectively reviewed to determine clinical characteristics and co‐morbidities of patients with elevated TRV on echocardiograms obtained under steady state conditions as an outpatient. Correlation of TRV ≥2.5 m/sec with age, sex, type of SCD, number of outpatient echocardiograms per patient, episodes of vasoocclusive crisis (VOC) and acute chest syndrome (ACS), mean hemoglobin and reticulocyte count, asthma, obstructive sleep apnea, cerebrovascular disease (CVD), and hydroxyurea therapy was determined.

Results

Of 224 SCD patients, 44 had outpatient echocardiographic measurement of TRV. Patients (11 of 44) (26.2%) with TRV ≥2.5 m/sec were compared to 31 patients without elevated TRV. Significant differences were noted for percent with HbSS disease (P = 0.041), CVD (P = 0.021), hemoglobin (P = 0.003), % reticulocytes (P = 0.037), and number of echocardiograms performed (P < 0.001). No significant differences were observed for gender, age, asthma, or frequency of VOC and ACS.

Conclusions

Elevated TRV, a surrogate marker for PHTN, occurs in children with SCD and is associated with low hemoglobin, elevated reticulocyte count, and cerebral vasculopathy. Appropriate screening by echocardiography can lead to detection and treatment that may reduce TRV and potentially reverse the disease process, prevent the increased morbidity and mortality associated with PHTN. © 2006 Wiley‐Liss, Inc.
Curing of composite components by ultraviolet radiation: A review
Authors: Endruweit A. , Johnson M. S. , Long A. C.
Published: February 2006

Curing of polymer matrices by ultraviolet (UV) irradiation can be applied to a variety of processes in the production of composite components, as long as the component can be directly irradiated. Wet lay‐up techniques, vacuum infusion type processes with UV‐transparent membranes, filament winding, and prepreg processes have been adapted to UV curing. Unlike in thermal curing, the curing time is in the order of magnitude of minutes rather than hours, which means a significant reduction in cycle time. The radiation can be generated by a variety of sources suitable for various specific applications and different curing strategies. The most frequently used radiation sources are mercury arc lamps. Because of the absorption of radiation passing through matter, the thickness of laminates for efficient application of UV curing is limited. The curing mechanism is either radical polymerization for acrylate‐based resins or cationic polymerization for epoxies and vinyl ethers. The properties of the UV‐cured polymer matrix are determined by the cross‐linking density. This depends on the type and concentration of the photoinitiator and of the (optional) diluents, the intensity and the duration of the irradiation, and the temperature at which the curing process takes place. POLYM. COMPOS., 27:119–128, 2006. © 2006 Society of Plastics Engineers.
Accelerated fatigue properties of unidirectional carbon/epoxy composite materials
Authors: Chen Hsing‐Sung , Hwang Shun‐Fa , Chen Hsing‐Sung
Published: February 2006

It has been confirmed that polymer matrix composites possess viscoelastic behavior. This means that one could accelerate the fatigue testing by changing the stress amplitude, frequency, or temperature. This study is to investigate the accelerated fatigue properties, which are resulted from the viscoelastic behavior, of carbon/epoxy composites and to predict their fatigue life. For this purpose, a series of fatigue tests of unidirectional specimens are conducted at room temperature under different stress ratios and stress frequencies. A group of sigmoid S‐N curves, which are suitable for the whole fatigue life, and the corresponding parameters are developed for different cyclic loading conditions. A transformation method, which can transform a reference S‐N curve to the corresponding S‐N curve of the assigned fatigue conditions, is established by the parameters. And this S‐N curve can be utilized to predict the fatigue life of the composite at the assigned stress ratio or stress frequency. The comparison between the linear and sigmoid S‐N curves is also carried out to show the advantages of the latter model in the whole fatigue life. POLYM. COMPOS., 27:138–146, 2006. © 2006 Society of Plastics Engineers
Characterization of polymeric biocomposite based on poly(vinyl alcohol) and poly(vinyl pyrrolidone)
Authors: Sedlařík Vladimír , Saha Nabanita , Kuřitka Ivo , Sáha Petr
Published: February 2006

Biocompatible and easily available materials from dairy production waste were used for modification of water‐soluble polymeric blends of Poly(vinyl alcohol) (PVA) and Poly(vinyl pyrrolidone) (PVP). The resulting biocomposites of PVA/PVP with various concentrations of lactose (L) or calcium lactate (CL) (0, 5, 15, 25, 35 wt%) were prepared by using a solvent cast technique and then characterized by optical microscopy, tensile test, water content determination, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy equipped by attenuated total reflectance device, and also tested for biodegradability. The films were transparent with a smooth surface. The results confirm that L and CL work as fillers in polymeric matrix. The tensile investigations showed enhanced Young's modulus (E) and tensile strength for low‐filled of composite materials (up to 5 wt% L and 15 wt% CL). The biodegradation test in aquatic conditions revealed improved biodegradability of modified blends. Both L and CL seem to be suitable for the modification of polymers, which can be convenient from economical and environmental point of view. POLYM. COMPOS., 27:147–152, 2006. © 2006 Society of Plastics Engineers.
Design and performance analysis of a self‐regulating melt pressure valve
Authors: Kazmer David , Gupta Dheeraj , Munavalli Mahesh , Kudchadkar Vijay , Nageri Ranjan
Published: February 2006

Net shape manufacturing of plastic products through injection molding, extrusion, and other polymer processing methods has been limited by a lack of observability and controllability of the state of the polymer melt. A self‐regulating valve is developed and validated that regulates the output melt pressure in proportion to an input control force. The valve relies on a valve pin that adjusts the juncture loss to balance the control force with the force exerted by the melt pressure on an exposed surface of the valve pin. Since the valve pin position is adjusted in accordance to natural laws, an open loop system design is feasible without need of any instrumentation or control system for closed loop feedback control. The design is analyzed using a three‐dimensional flow analysis that utilizes independent shear and elongational viscosities for the polymer melt. Pressure drops and shear stresses through the valve are analyzed to estimate the steady state error in the output pressure when the valve pin is controlled in an open loop mode (i.e. without melt pressure feedback). Guidelines for the valve design are provided to achieve a reasonable trade‐off between flow and structural requirements. Finally, experimental validation indicates an excellent level of response and consistency given the simplicity of the design. POLYM. ENG. SCI. 46:549–557, 2006. © 2006 Society of Plastics Engineers
Nonisothermal comprehensive 3D analysis of polymer melt flow in a coat‐hanger die
Authors: Wu Tingqi , Jiang Bo , Xu Shuhua , Bi Chao
Published: February 2006

The nonisothermal flow of Carreau fluid in a coat‐hanger die is studied. A general three‐dimensional finite volume code is developed for the purpose of flow analysis. The isobars, the isotherms, and the velocity distribution are obtained. Simulation results illustrated that the highest temperature occurred by the center of manifold, rather than the die‐lip region because of the combined effects of high shear rate and poor heat conduction, which is important for processing those heat‐sensitive materials. In the regions where die gap is relatively small, the wall temperature plays a key role in deciding temperature distribution in the melt. The validity of simulation results is verified experimentally. POLYM. ENG. SCI., 46:406–415, 2006. © 2006 Society of Plastics Engineers.
Manufacturing and foaming of high melt viscosity of polypropylene by using electron beam radiation technology
Authors: Han Do‐Hung , Jang Jae‐Hyuk , Kim Hye‐Young , Kim Byung‐Nam , Shin Boo‐Young
Published: February 2006

The high melt viscosity of polypropylene was studied by grafting bifunctional monomers, 1,6‐hexanediol diacrylate (HDDA) and tripropylene glycol diacrylate (TPGDA), onto homopolypropylene (HPP) and random ter‐polypropylene (RTPP) under electron‐beam irradiation. Creation of the high‐melt‐viscosity polypropylene was possible at low radiation dosage and low monomer content, under a prohibition of both radiation degradation and homopolymerization. TPGDA monomer was more effective in increasing the melt viscosity of HPP compared with RTPP, whereas HDDA monomer was more effective for enhancing the melt viscosity of RTPP. Such different effects of monomers on melt viscosity may arise from different monomer structures, namely, TPGDA has additional three methyl groups, but HDDA has no methyl groups. Electron‐beam radiation technology, on an increase of the melt viscosity, was much more effective in HPP than RTPP, when compared with virgin polymers. Modified RTPP and HPP with high melt viscosity were capable of foaming with numerous fine cells, of which the modified HPP with 1.5 mmol TPGDA and 0.5 kGy could create more spherical foam cells and its bending strength was 1.5 times more than that of the foamed RTPP. POLYM. ENG. SCI., 46:431–437, 2006. © 2006 Society of Plastics Engineers.
Finite strain 3D thermoviscoelastic constitutive model for shape memory polymers
Authors: Diani Julie , Liu Yiping , Gall Ken
Published: February 2006

A 3D thermoviscoelastic model is proposed to represent the thermomechanical behavior of shape memory polymers. The model is based on a physical understanding of the material behavior and a mechanical interpretation of the stress–strain–temperature changes observed during thermomechanical loading. The model is thermodynamically motivated and is formulated in a finite strain framework in order to account for large strain deformations. Model predictions capture critical features of shape memory polymer deformation and, in some cases, provide very favorable comparisons with experimental results. POLYM. ENG. SCI. 46:486–492, 2006. © 2006 Society of Plastics Engineers.
Comparative analysis of radical‐mediated polyethylene modifications: Vinyltriethoxysilane versus mercaptopropyltriethoxysilane addition
Authors: Sengupta Saurav S. , Parent J. Scott
Published: February 2006

The efficiency and selectivity of two approaches for introducing alkoxysilane functionality to polyethylene (PE) are examined along with the moisture‐curing performance of the resulting products. Although the peroxide‐initiated grafting of vinyltriethoxysilane to PE is accompanied by undesirable crosslinking, comparable silane contents can be introduced without affecting the melt viscosity through the addition of mercaptopropyltriethoxysilane (MPTES) to the unsaturation within the polymer. Rapid hydrogen atom donation by thiols underlies this unique selectivity for grafting versus molecular weight alteration, and gives rise to a remarkable tolerance of MPTES additions to phenolic antioxidants. Direct comparisons of the moisture‐curing efficiencies provided by the two functionalization techniques reveal few significant differences in crosslink yields or composition distributions. POLYM. ENG. SCI., 46:480–485, 2006. © 2006 Society of Plastics Engineers.
Synthesis of a novel hexaarylbiimidazole with ether groups and characterization of its photoinitiation properties for acrylate derivatives
Authors: Shi Yongtao , Yin Jie , Kaji Makoto , Yori Hanako
Published: February 2006

A novel photoinitiator 2,2′‐bis‐(2‐chlorophenyl)‐4,4′,5,5′‐tetra‐[3‐(2‐hydroxylmethyl‐2‐triethylene glycol monoethylene ether‐ethane‐1‐oxy)‐phenyl]‐1,2′‐biimidazole (BCTE‐HABI) was synthesized from 3,3′‐dimethoxy benzoin. Ultraviolet spectra, fluorescence spectra, ESR, photodilatometer, and photo‐DSC measurements indicate that its photoinitiating activity for acrylate derivatives is better than 2,2′‐bis‐(2‐chlorophenyl)‐4,4′,5,5′‐tetraphenyl‐1,2′‐biimidazole (o‐Cl‐HABI), which is one of the most widely studied and used derivatives of HABI. POLYM. ENG. SCI., 46:474–479, 2006. © 2006 Society of Plastics Engineers.
Rheology of wood plastics melt, part 2: Effects of lubricating systems in HDPE/maple composites
Authors: Li T. Q. , Wolcott M. P.
Published: February 2006

Rheology of HDPE/maple formulations with two common lubricating systems was studied with the capillary rheometry and the small‐amplitude oscillatory shear experiments. Shear and extensional flow data in the capillary dies revealed different lubricating roles of the additives. Small‐amplitude oscillatory tests using a rotational parallel plate rheometer were performed to further investigate the effects of additives. The ester‐type lubricant was found to both enhance maple filler dispersion and promote excellent external lubrication. The zinc stearate‐N,N′‐ethylene bis‐stearamide lubricating system, however, was shown to bear the potential of causing certain adverse effects and its role could not be fully illustrated with the capillary rheometry and the oscillatory tests based on linear viscoelasticity assumptions. Synergistic and simple rule‐of‐mixture effects were identified for different lubricating systems. POLYM. ENG. SCI., 46:464–473, 2006. © 2006 Society of Plastics Engineers.
A study of the effects of postcure treatments on polyester–melamine coating matrices
Authors: Gamage N.J.W. , Hill D.J.T. , Pomery P.J. , Lukey C. A.
Published: February 2006

The effect of postcure high energy (γ), ultraviolet (UV) and thermal treatment on the properties of polyester–melamine clearcoats of a range of compositions has been investigated. Two initial cure conditions were used, of which one was “optimally” cured and the other under‐cured. It was found that postcure treatments, particularly γ and UV, led to coatings of similar mechanical and thermal properties irrespective of initial cure, although the change in properties on postcure treatment was greater for the under‐cured samples. The results were interpreted in terms of the effect of the treatments on the structure of the crosslinked matrices. The study suggests the possibility of the development of a dual‐cure process for polyester–melamines, whereby cure optimization and property improvement can be achieved. This could also be used to “correct” for small variations in thermal cure levels brought about by adventitious on‐line fluctuations in cure oven conditions. POLYM. ENG. SCI. 46:532–539, 2006. © 2006 Society of Plastics Engineers
Proteomic analysis of Candida albicans yeast and hyphal cell wall and associated proteins
Authors: Ebanks Roger O. , Chisholm Kenneth , McKinnon Stewart , Whiteway Malcolm , Pinto Devanand M.
Published: February 2006

Candida albicans is an important human pathogen that causes systemic infections, predominantly among populations with weakened immune systems. The morphological transition from the yeast to the hyphal state is one of the key factors in C. albicans pathogenesis. Owing to their location at the host–pathogen interface, the cell wall and associated proteins are of interest, especially with respect to the yeast to hyphal transition. This study entailed the proteomic analysis of differentially regulated proteins involved in this transition. The protein profiles of C. albicans DTT/SDS‐extractible proteins and the cyanogen bromide (CNBr)/trypsin‐extractable proteins of a cell wall‐enriched fraction from yeast and hyphae were compared. In total, 107 spots were identified from the DTT/SDS‐extractible cell wall‐enriched fraction, corresponding to 82 unique proteins. Of these DTT/SDS‐extractible proteins, 14 proteins were upregulated and 10 were downregulated in response to hyphal induction. Approximately 6–9% of total cell wall‐protein‐enriched fraction was found to be resistant to DTT/SDS extraction. Analysis of the DTT/SDS‐resistant fraction using a CNBr/trypsin extraction resulted in the identification of 29 proteins. Of these, 17 were identified only in the hyphae, four were identified only in the yeast, and eight were identified in both the yeast and hyphae.
Overexpression and elevated serum levels of phosphoglycerate kinase 1 in pancreatic ductal adenocarcinoma
Authors: Hwang Tsann‐Long , Liang Ying , Chien Kuan‐Yi , Yu Jau‐Song
Published: February 2006

Pancreatic ductal adenocarcinoma (PDAC) is a common malignancy with a very low 5‐year survival rate. Currently, there are no valid markers for early detection and targets for therapy. Here, we used 2‐DE to analyze the protein profiles of eight PDAC specimens and paired adjacent nontumor tissues. MS was used to identify 15 protein spots that were found to be overexpressed in PDAC tissues versus adjacent controls. One of them was identified as phosphoglycerate kinase (PGK) 1, a secretable glycolytic enzyme known to participate in angiogenesis. Immunohistochemical analysis of 63 PDAC specimens revealed moderate to strong expression of PGK1 in >70% of the tumors. Further Western blotting analysis of cells from tumor and adjacent nontumor tissues obtained by laser capture microdissection confirmed the enhanced expression of PGK1 in tumor cells. Furthermore, the serum levels of PGK1 were significantly higher in PDAC patients (n = 21) than in the control group (n = 25) (p < 0.005), as determined by ELISA. These observations indicate that protein profile analysis using a combination of 2‐DE and MS provides an effective strategy for identifying biomarkers that may have diagnostic potential for PDAC, and identify PGK1 as a potential biomarker and/or therapeutic target for PDAC.
Thermal Damage on LX‐04 Mock Material and Gas Permeability Assessment
Authors: Hsu Peter C. , DeHaven Martin , McClelland Matthew , Maienschein Jon L.
Published: February 2006

RM‐04‐BR, a mock material for the plastic‐bonded HMX‐based explosive LX‐04, is characterized after being thermally damaged at 140 °C and 190 °C. We measured the following material properties before and after the thermal experiments: sample volume, density, sound speed, and gas permeability in the material. Thermal treatment of the mock material leads to de‐coloring and insignificant weight loss. The sample expanded, resulting in density reductions of 1.0% to 2.5% at 140 °C and 190 °C, respectively. Permeability in the mock samples was found to increase from 10−16 to 10−15 m2, as the porosity increased. The permeability measurements are well represented by the Blake‐Kozeny equation for laminar flow through porous media. The results are similar to the gas permeability in PBX‐9501 obtained by other researchers [1, 2].
Nanostructured Energetic Composites of CL‐20 and Binders Synthesized by Sol Gel Methods
Authors: Li Jun , Brill Thomas B.
Published: February 2006

Monolithic energetic gels were prepared in acetone by separately cross‐linking the single precursors, glycidyl azide polyol (GAP polyol polyol), nitrocellulose (NC, 12% N), and tris(hydroxymethyl)nitromethane (THMNM) and the mixed precursors (GAP polyol+NC) and (GAP polyol+THMNM) with hexamethylene diisocyanate (HDI). THMNM functions as a chain extender. The synthesis conditions were optimized according to precursor mass ratio, cross‐linking agent, solvent, catalyst concentration, and containers with various surface‐to‐volume ratios. The concentrations of reactants and cure catalyst are the most important factors. The composite energetic materials with a high degree of homogeneity were synthesized by trapping hexanitrohexazaisowurtzitane (CL‐20) on the nano scale in the energetic polymer gels using sol gel processing with a modified freeze‐drying procedure. Loadings up to 85%, 93%, and 90% by weight of CL‐20 yielded, respectively, monolithic gels for GAP/HDI, NC/HDI, and THMNM/HDI. 90% CL‐20 can be loaded into gels of the mixed precursors of (GAP polyol+NC) and (GAP polyol+THMNM). The energetic gels and composites were characterized using FT‐IR spectroscopy, DSC, SEM, and sensitivity to drop weight impact. The sensitivity of CL‐20 is reduced in the energetic nanocomposites.
A simple clustering algorithm can be accurate enough for use in calculations of pKs in macromolecules
Authors: Myers Jonathan , Grothaus Greg , Narayanan Shivaram , Onufriev Alexey
Published: February 2006

Structure and function of macromolecules depend critically on the ionization states of their acidic and basic groups. Most current structure‐based theoretical methods that predict pK of ionizable groups in macromolecules include, as one of the key steps, a computation of the partition sum (Boltzmann average) over all possible protonation microstates. As the number of these microstates depends exponentially on the number of ionizable groups present in the molecule, direct computation of the sum is not realistically feasible for many typical proteins that may have tens or even hundreds of ionizable groups. We have tested a simple and robust approximate algorithm for computing these partition sums for macromolecules. The method subdivides the interacting sites into independent clusters, based upon the strength of site–site electrostatic interaction. The resulting partition function is factorizable into computationally manageable components. Two variants of the approach are presented and validated on a representative test set of 602 proteins, by comparing the pK1/2 values computed by the proposed method with those obtained by the standard Monte Carlo approach used as a reference. With 95% confidence, the relative error introduced by the more accurate of the two methods is less than 0.25 pK units. The algorithms are one to two orders of magnitude faster than the Monte Carlo method, with the typical settings. A graphical representation is introduced that visualizes the clusters of strong site–site interactions in the context of the three‐dimensional (3D) structure of the macromolecule, facilitating identification of functionally important clusters of ionizable groups; the approach is exemplified on two proteins, bacteriorhodopsin and myoglobin. Proteins 2006. © 2006 Wiley‐Liss, Inc.