bluuebunny/crossref_metadata_2025 huggingface dataset:
Imaging Science in Medicine
Authors: Hendee William R.
Published: October 2003

The use of imaging technologies has expanded tremendously in medicine over the past two decades. This expansion reflects the evolution of new imaging tools that reveal human anatomy and physiology in ever‐increasing detail, as well as the development of digital data acquisition and processing techniques that extract information from human tissues in ever‐expanding degrees of subtlety. A further factor that is stimulating growth in imaging is the expansion of knowledge about biological systems at the cellular, molecular, and genetic levels. This factor is transforming medical imaging from a “technology‐push” discipline into one where fundamental biological questions, as well as important clinical issues, are the force driving development of new imaging technologies. This transformation demands enhanced knowledge about the interface between biological properties of tissues and the characteristics of imaging systems. Exploration of the existing state of knowledge about the interface, and what is needed for the immediate future, is the subject of this article.
Ultrasound Imaging
Authors: Rao Navalgund A. H. K.
Published: October 2003

Ultrasound is defined as sound waves whose frequency is above 20 kHz, the upper limit of the human audible range. The past century has witnessed the growth of an imaging technology that uses ultrasound as the information carrier. A physical medium is required to sustain longitudinal and transverse ultrasound waves. The imaging can be passive, when the object to be detected is the source of sound, or active, when an external deliberately controlled source of sound is used and the echoes from objects in the medium are used to generate an image. State‐of‐the‐art active systems can launch waves into a medium and nondestructively collect echo signals and display information pertaining to the inside of an optically opaque three‐dimensional object. In medical applications, the propagation medium is soft tissue. Present day technology permits real‐time (20 or more image frames per second) visualization of the gross anatomy and pathology. Medical ultrasound has found applications throughout the breadth of diagnostic investigations that includes obstetrics, gynecology, abdomen, ophthalmology, cardiovascular system, breast, and superficial structures. Besides medical applications, ultrasound is also used in nondestructive evaluation (NDE) and sound navigation and ranging (SONAR). NDE is commonly used in the aerospace and nuclear power industries to inspect safety‐critical parts for flaws during in‐service use. The medium here is generally solid material. SONAR pertains to imaging under the sea. The imaging techniques and technologies used in these different application areas are quite similar, at least for medical and NDE. Therefore, the main body of the discussion centers on medical imaging.

An ultrasound imaging system usually conveys information about echo generating objects. The image can be thought of as a display of the multidimensional spatial distribution of some object‐dependent entity. Visualization of this information is one of the objectives, and perhaps the major objective in medical ultrasound. The image value is generally related to the mechanical or elastic property of the object. A secondary objective therefore is to understand and quantify the relationship between the image value and the object property, also known as quantitative imaging or tissue characterization in medical ultrasound. This area still remains a subject of active research. This article deals only with the first objective.

The three steps involved in the imaging process, namely, transduction and reception by the transducer, two‐way propagation in the medium to some depth, and the scattering/reflection phenomenon are considered in detail. Different modes of scanning and information display employed in medical diagnosis and NDE are considered.
X‐Ray Fluorescence Imaging
Authors: Chang Shih‐Lin
Published: October 2003

In Wilhelm Conrad Röntgen's cathode‐ray‐tube experiments, the lighting up of a screen made from barium platinocyanide crystals due to fluorescence led to his discovery of X rays in 1895. Subsequent investigations by Röntgen and by Straubel and Winkelmann showed that the radiation that emanated from a fluorspar, or fluorite crystal CaF2excited by X rays is more absorbing than the incident X rays. This so‐called fluorspar radiation is X‐ray fluorescence. Nowadays, it is known that X‐ray fluorescence is one of the by‐products of the interaction of electromagnetic (EM) waves with the atoms in matter in the X‐ray regime (0.1–500 Å).

X‐ray fluorescence is a two‐step process; X‐ray absorption (the ejection of an inner electron) and X‐ray emission (the recapture of an electron). Both involve the electron configuration of atoms in the irradiated material.

An X‐ray fluorescent image is usually obtained by following these steps: The incident X‐ray beam, after proper monochromatization and collimation, impinges on a sample of interest. An absorption spectrum is acquired by scanning the monochromator to identify the locations of the absorption edges of the element investigated. The incident beam is tuned to photon energies higher than the absorption edges so that the constituent elements of the sample are excited. Then, X‐ray fluorescence emanates. The spatial distribution of the fluorescent intensity, the fluorescent image, is recorded on a two‐dimensional detector or on a point detector using a proper scan scheme for the sample. The following items need to be considered for good quality images of high spatial and spectral resolution: (1) appropriate X‐ray optics for shaping the incident beam and for analyzing the fluoresced X rays and (2) a suitable scanning scheme for the sample to cross the incident beam. In addition, image reconstruction of intensity data versus position is also important for direct mapping of the trace elements in a sample.
Photoconductor Detector Technology
Authors: Melnyk Andrew
Published: October 2003

Photoelectric detectors are semiconducting devices that convert optical signals into electrical signals. They rely on the quantum nature of matter, whereby incident photons, ranging from high energy gamma rays through visible light to infrared rays, excite electrons in matter to produce an electrical charge. The operation of a photoelectric detector involves two steps: (1) conducting charge generation by an incident light photon and (2) charge transport and/or multiplication by whatever current gain mechanism may be present. Photoelectric detectors are classified as photoemission and photoconductive detectors. Photoemission occurs when the energy of the photonhν is sufficient to eject an electron from the surface of the solid into vacuum, and the phenomenon is the basis for photomultiplier tubes. Photoconductivity, sometimes referred to as internal photoemission, is observed in a solid when the absorbed photon raises an electron from a nonconducting energy state to a conducting energy state where it contributes to electrical conductivity.

This article on photoconducting detectors explains the fundamental concepts of photoconductivity and describes the elementary photoconducting devices, their design, materials, and how they work. Except for two, photodectors incorporated in specific imaging devices and an explanation of their operation are not considered here because they are discussed in other sections on specific applications such as UV or IR detectors, CCD imagers, etc. The exceptions are electrophotographic and vidicon‐type television camera photoconductors that can be understood only as imaging devices. In contrast to other imaging photodetectors, electrophotographic photoconductors are not covered in any other sections. For this reason and because they differ significantly in their design, materials and operation from the other photodetectors, most of this section is devoted to a detailed discussion of electrophotographic photoconductors.
Oral‐facial‐digital syndrome VII is oral‐facial‐digital syndrome I: A clarification
Authors: Nowaczyk Malgorzata J.M. , Zeesman Susan , Whelan Donald T. , Wright Victoria , Feather Sally A.
Published: October 2003

We report on further clinical findings in the one single family in the literature classified as oral‐facial‐digital (OFD) type VII in order to demonstrate that the diagnosis in this kindred should, in fact, be OFD type I. The mother and the daughter described in the original report have since developed polycystic kidney disease. In addition, the daughter recently had a daughter of her own with central nervous system, oral and digital anomalies. Linkage studies have shown that all the affected women share the same haplotype across the previously identified region Xp22.2p22.3 to which OFD I maps. Although the pedigree was too small for a significant lod score, the combination of clinical and molecular information clearly shows that the disease in this family is OFD I. We report this family in order to clarify and simplify the classification of the oral‐facial‐digital syndrome spectrum and to recommend the removal of OFD VII from the classification system of the oral‐facial‐digital syndromes. © 2003 Wiley‐Liss, Inc.
MECP2 gene mutations in non‐syndromic X‐linked mental retardation: Phenotype–genotype correlation
Authors: Gomot Marie , Gendrot Chantal , Verloes Alain , Raynaud Martine , David Albert , Yntema Helger G. , Dessay Sabine , Kalscheuer Vera , Frints Suzanne , Couvert Philippe , Briault Sylvain , Blesson Sophie , Toutain Annick , Chelly Jamel , Desportes Vincent , Moraine Claude
Published: October 2003

Non‐syndromic X‐linked mental retardation (MRX) is a frequent cause of inherited mental retardation. It is a heterogeneous condition in which the first 12 genes discovered to date explain no more than 15% of the MRX situations ascertained by recurrence in multiplex families. In Rett syndrome (RTT), an X‐linked dominant condition mostly sporadic and usually lethal in males, most affected females have been shown to be mutated in the Methyl–CpG binding protein 2 gene (MECP2) that maps at Xq28. Some mentally retarded males related to RTT females carry the same mutation. Several MRX families mapping to Xq28 were subsequently tested for MECP2 and a causative mutation was discovered in three families, suggesting that it could be one of the main genes involved in MRX. We report here the corresponding phenotypes in these three families of increasing severity. In family 1, an in‐frame deletion ΔP387‐M466 was found in the 3′ region. The patients had severe to mild non‐progressive MR, with better motor skills than verbal abilities. In family 2, an Arg to Trp substitution (R167W) was found between the transcription repression domain (TRD) and the methyl binding domain (MBD). The patients had brisk reflexes and essential tremor with mild and non‐progressive MR, poor motor co‐ordination and written language difficulties. In the third family (MRX16), a Glu to Gly substitution (E137G) was found in the MBD. The patients had manifestations similar to those of family 2, but MR was mild to moderate, speech articulation was poor and some had verbal stereotypies. Regression of language skills was suspected in three patients. Phenotype–genotype correlation could thus be suspected and is discussed in these three families. © 2003 Wiley‐Liss, Inc.
Novel homoplasmic mutation in the mitochondrial tRNATyr gene associated with atypical mitochondrial cytopathy presenting with focal segmental glomerulosclerosis
Authors: Scaglia Fernando , Vogel Hannes , Hawkins Edith P. , Vladutiu Georgirene D. , Liu Ling‐Ling , Wong Lee‐Jun C.
Published: October 2003

We report a 9‐year‐old girl with a mitochondrial cytopathy preceded by steroid‐resistant focal segmental glomerulosclerosis (FSGS). The proband presented at the age of 2 years with steroid‐resistant nephrotic syndrome caused by FSGS. Her renal function progressively deteriorated and a dilated cardiomyopathy developed at the age of 7 years. A skeletal muscle biopsy showed a combined respiratory chain (RC) defect and a partial deficiency of coenzyme Q10. A novel mutation in the evolutionary highly conserved region of the mitochondrial tRNATyr gene was found in homoplasmic state in skeletal muscle, blood, and renal tissue. The mutation was also found in homoplasmic state in her mildly symptomatic mother. No other maternal family members were available for testing. The present case of mitochondrial cytopathy initially presenting with steroid‐resistant nephrotic syndrome, unusual biochemical and renal findings associated with a novel tRNA point mutation suggests that steroid‐resistant FSGS can predate other features of mitochondrial disease for a prolonged period of time and that the progressive glomerulopathy associated with combined mitochondrial RC defects is genetically heterogeneous. © 2003 Wiley‐Liss, Inc.
Stress development in drying fibers and spheres
Authors: Lei Herong , Francis Lorraine F. , Gerberich William W. , Scriven L. E.
Published: October 2003

Stress development during drying is a critical factor that affects the final structure and properties of a coated fiber or spherical product. Stress development during drying of the coating is due to nonuniform shrinkage and physical constraints. In this study, a large deformation elasto‐viscoplastic model is developed to predict stress development in drying fibers and spheres after the coatings solidify. From the model, stress evolution in the drying fibers/spheres can be predicted by a partial differential equation of diffusion in one dimension, a first‐order partial differential equation of pressure distribution, and two ordinary differential equations on local evolution of the stress‐free state. The system of equations is solved by the Galerkin/finite element method in the one dimensional axial/spherical symmetric coatings. Solutions show changes in solvent concentration and viscous stress as the coating dries. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3934–3944, 2003
Deformation, yield and fracture of elastomer‐modified polypropylene
Authors: Zebarjad S. M. , Bagheri R. , Reihani S. M. Seyed , Lazzeri A.
Published: October 2003

In recent decades, great attention has been devoted to the toughening of isotactic poly(propylene) (PP) with elastomers such as ethylene–propylene rubber (EPR). The most important reasons for this interest are the moderate cost and favorable properties of PP. This article is focused on the role of EPR in the deformation and fracture mechanism of PP/EPR blends with different volume fractions of elastomer phase. Differential scanning calorimetry (DSC), tensile tests, and microscopy techniques were used in this study. The fracture mechanism of isotactic PP toughened by EPR (PP/EPR) has also been studied by three point bending (3‐PB) and four point bending (4‐PB) tests. Rubber particle cavitation appears to be the main mechanism of microvoid formation, although some matrix/particle debonding was observed. The investigation of the toughening mechanism shows that a wide damage zone spreads in front of the pre‐crack. Optical microscopy (OM) illustrates that, in pure PP, crazing is the only fracture mechanism, and no evidence of shear yielding is found, while in PP blends craze‐like features associated with shear yielding are observed, which have been identified as high shear localized dilatational bands. This type of deformation pattern supports a model previously proposed by Lazzeri1 to explain the interparticle distance effect on the basis of the stabilization effect on dilatational band propagation exerted by stretched rubber particles. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3767–3779, 2003
Silicone elastomers for electronic applications. II. Effects of noncrosslinked materials
Authors: Andersson L. H. U. , Johander P. , Hjertberg T.
Published: October 2003

We performed applied functional tests to examine how the noncrosslinked fraction of a cured silicone elastomer affected the performance of electrical devices and the solderability and adhesion on gold‐plated printed circuit boards. To obtain information about the spreading tendencies of commercial silicone elastomers, and to complement the function tests, we conducted so‐called creep tests to examine the migration and spreading of the noncrosslinked fraction. The electrical tests, performed with both reference oligomers and cured commercial poly(dimethyl siloxane)s, showed that failure occurred even at very low silicone contamination levels. The solderability and adhesion, however, were not affected by the presence of poly(dimethyl siloxane)s, especially not the reference solutions, which consisted mainly of volatile siloxanes. The creep tests, performed on commercial silicone elastomers, indicated that the noncrosslinked, nonvolatile part had to be taken into account in a discussion of silicone contamination. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3780–3789, 2003
Preparation and properties of water‐resistant soy dreg/benzyl konjac glucomannan composite plastics
Authors: Chen Yun , Zhang Lina , Lu Yongshang , Ye Changsheng , Du Libo
Published: October 2003

ABTSRACT:

Biodegradable plastics based on soy dreg (SD) were prepared with glycerol as a plasticizer via compression molding at 110–160°C. The effects of the glycerol content and molding temperature on the processability and mechanical properties were investigated. For enhanced water resistivity of the SD plastics, thermoplastic benzyl konjac glucomannan (B‐KGM) films were covered on SD sheets in a lamination compression process, and SD/B‐KGM (SB) composite sheets were obtained. The structure and properties of the SB sheets were studied with Fourier transform infrared spectroscopy, dynamic mechanical thermal analysis (DMTA), scanning electron microscopy, and tensile testing. The results indicated that the tensile strength of the SB sheets was enhanced to 13.2 MPa in the dry state and to 11.4 MPa in the wet state. The water resistivity of the SB sheets with B‐KGM covers increased from 0.03 to 0.86 with an increase in the B‐KGM thickness from 0 to 35 μm. The multipeaks of a tan δ relaxation that appeared in the DMTA spectra for SB series sheets were due to multicomponents such as soy protein, cellulose, polysaccharide, and B‐KGM. The tan δ transition temperature and the decomposition temperature of cellulose in SB sheets were higher than those in SD sheets without B‐KGM covers. This work provided a simple way of improving the compression‐molding processability and water resistivity of SD plastics for practical applications. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3790–3796, 2003
Cure modification of natural rubber containing benzothiazole accelerators by some modified thiocarbamyl sulfenamides
Authors: Datta R. N. , Debnath S. C. , Noordermeer J. W. M.
Published: October 2003

The effects of N‐cyclopentamethylene thiocarbamyl‐N′‐(cyclohexyl,thiocyclohexyl)sulfenamide (CPCTS) and N‐oxydiethylene thiocarbamyl‐N′‐(cyclohexyl,thiocyclohexyl)sulfenamide (ODCTS) as cure modifiers on the vulcanization of natural rubber (NR) containing benzothiazole accelerators were studied. CPCTS and ODCTS were used separately with 2‐mercaptobenzothiazole and N‐oxydiethylene benzothiazole sulfenamide to determine their effects on these accelerators. CPCTS and ODCTS retarded the accelerators. Enhanced activity was found with respect to the torque, scorch, modulus, and tensile strength and was believed to be due to the formation of different intermediate components during the early stage of the vulcanization of NR. Reactions likely responsible for acceleration and retardation were explored. CPCTS and ODCTS provided better cure retardation than N‐cyclohexyl thiophthalimide. The chemical characterization of the NR vulcanizates correlated with the physical properties obtained at 140°C. Stocks containing CPCTS or ODCTS produced mostly monosulfide linkages, which were affected when N‐cyclohexyl thiophthalimide was used. This provided information concerning the heat‐resistance properties of the vulcanizates. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3835–3847, 2003
Interfacial tension measurements and evidence of order in high‐density polyethylene melts
Authors: Chan Colleen C. V. , Elliott Janet A. W. , Williams Michael C.
Published: October 2003

Polyethylene (PE) is a widely used product commercially. However, our knowledge is incomplete about the properties of high‐density polyethylene (HDPE) at temperatures above its melting point, where solid crystals disappear. Recently, there has been increasing evidence from rheological, differential scanning calorimetry, and NMR studies that suggests the presence of microstructural order in the bulk of PE melts. In this study, the interfacial tension of HDPE melts in contact with silicone oil was measured with a spinning drop tensiometer in the same temperature range in which phase transitions have been observed in the bulk HDPE. Anomalous temperature dependence of interfacial tension was found between 200 and 230°C. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 4061–4067, 2003
Synthesis, characterization, and blood compatibility of copolymers of polyamidoamines and n‐vinylpyrrolidone
Authors: Kumar Dey Ratan , Ray Alok R.
Published: October 2003

Two new polyamidoamines derived from piperazine (Pip)/cyclohexylamine (CHA) and N,N′‐methylene bisacrylamide (MBA) were synthesized and subsequently copolymerized with N‐vinylpyrrolidone (NVP) under suitable reaction conditions to yield the respective copolymers (Pip–MBA–NVP and CHA–MBA–NVP). The synthesized materials were characterized by spectroscopic techniques. The material surface characteristics were checked by contact angle measurement, and the data established the relative hydrophilic characteristics of the synthesized copolymers with respect to the control poly(N‐vinylpyrrolidone). A thrombus‐formation study indicated less (<1.2 mg) clot formation on the heparinized material surfaces within a 30‐min contact time with the acid citrate dextrose human blood. The percentage of hemolysis of the blood by the materials was also less than 5%. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 4068–4074, 2003
New method of dyeing keratin fibers using poly(ethylene imine) and its coloring mechanism
Authors: Kuzuhara A. , Hori T.
Published: October 2003

To improve the colorability of keratin fibers at lower temperatures, we developed a novel coloring method using poly(ethylene imine) (PEI) as a counterion reagent (human hair was treated beforehand with a PEI solution and then was colored with an acid dye). As a result of this new method, the coloring and color fastness to shampooing clearly improved with respect to the usual method. Next, to study the coloring mechanism with PEI, we investigated the penetration of PEI and Orange II into bleached human hair by optical microscopy. The results showed that the penetration of PEI and Orange II into bleached human hair increased with an increasing PEI treatment time and with a decreasing PEI molecular weight. With these experiments, we demonstrated that PEI, which penetrated the cortex region, exerted counterionization on Orange II, thereby increasing the penetration of Orange II into bleached human hair. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3806–3810, 2003
Study on the synthesis, characterization, and sorption of some metal ions on gelatin‐ and acrylamide‐based hydrogels
Authors: Chauhan Ghanshyam S. , Kumar Suresh , Kumari Anita , Sharma Rakesh
Published: October 2003

Graft copolymers and networks of gelatin were synthesized with three acrylamides (acrylamide, 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid, and N‐iso‐propylacrylamide) by using a redox initiator system consisting of ammonium peroxysulfate–ferrous ammonium sulfate in either the absence or the presence of a crosslinker (N,N‐methylene bisacrylamide) at two temperatures. Characterization of synthesized polymers was studied by FTIR and thermal studies to investigate evidence of grafting or interpenetrating network formation and to investigate the effect of reaction conditions and crosslinker concentration on the properties of synthesized polymers. Detailed investigation into water‐uptake properties of these hydrogels was carried out as a function of time, temperature, and pH. The inherent properties of the monomer incorporated onto gelatin collectively act as determinant of the water‐absorption behavior of the hydrogels. Sorption of Fe+2, Cr+6, and Cu+2 ions from their aqueous solutions was also studied on select hydrogels, where it was observed that metal ions are sorbed by effective partitioning between hydrogels and solution phase and apart from the nature of metal ions, and structural aspects of hydrogels also determine the quantum of metal ion uptake. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3856–3871, 2003
Synthesis of trimellitic anhydride microcapsule toner by liquid‐phase separation
Authors: Teshima Katsuya
Published: October 2003

A microcapsule toner containing trimellitic anhydride for use as a foam inhibitor in printing applications was synthesized by liquid‐phase separation in organic solvents. It is possible to determine materials appropriate for the microencapsulation of trimellitic anhydride from solubility parameters calculated on the basis of the molecular structures of raw material candidates. Considering solubility parameters of various polymers, the polyethylene/methacrylic acid copolymer was selected for the microcapsule wall material. In addition, two kinds of solvents, toluene [solvent (a)] and isoparaffin [solvent (b)], were employed. It was necessary for the microcapsule materials to meet the following conditions: (1) the wall material must completely dissolve in solvent (a); (2) the core material must disperse well, but not dissolve in solvent (a); and (3) the wall and core materials must not dissolve in solvent (b). By using mixtures of either lecithin and basic barium petronate or lecithin and basic calcium petronate as charge control agents, the trimellitic anhydride microcapsules could be charged either positively and negatively, respectively. The microcapsule toner fabricated in this method was successfully applied in commercial printing machines, where it inhibited foaming effectively enough to satisfy product requirements in the printing industry. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3822–3826, 2003
Elucidation of the miniemulsion stabilization mechanism and polymerization kinetics
Authors: Anderson Christopher D. , Sudol E. David , El‐Aasser Mohamed S.
Published: October 2003

Styrene/hexadecane miniemulsions were polymerized at 50°C using a redox initiator. The miniemulsions and their corresponding latexes were characterized in terms of size, polymerization rate, and surface properties. The resulting data were analyzed to elucidate the miniemulsion stabilization and polymerization mechanisms. It was found that the free surfactant concentration exceeded the critical micelle concentration when large amounts of surfactant (60 mM sodium lauryl sulfate) were used, resulting in simultaneous micellar and droplet nucleation. Most surfactant was on the surface of the droplets (85%) or particles (95%). The fractional surface coverage was proportional to the surfactant concentration to the 0.55 power. Using a particle diameter equation, the number of particles was calculated to be proportional to the surfactant concentration to the 1.35 power. Through direct particle size measurements, a power of 1.38 was confirmed. The rate of polymerization was determined by reaction calorimetry to be proportional to the number of particles to the 0.59 power, in contrast to classical Smith–Ewart kinetics for conventional emulsions (1.0 power). The average number of radicals per particle was estimated from the rate and number data, and varied with the particle diameter to the 0.97 power. The observed kinetic dependencies were validated through an extension of Smith–Ewart theory. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3987–3993, 2003
Natural abundance 15n solid‐state nmr study of nylon‐6 in blends
Authors: Tavares Maria Inês B. , De Souza Cláudia M. G.
Published: October 2003

Natural abundance solid‐state nuclear magnetic resonance spectroscopy (NMR) of nitrogen‐15 (15N) was applied to investigate the films of nylon‐6 and their blends with poly(propylene oxide) (PPO). The NMR 15N results allowed us to identify the crystalline forms present in these blends and also confirmed the previous NMR results obtained by 13C‐NMR study. From all NMR data the antiplasticization phenomena and plasticization effects caused by PPO content, in the blends were characterized. The polyoxide action is a function of its proportion. However, because the samples were prepared by solution casting, the residual solvent action cannot be ignored. The 15N chemical shift changes were influenced by both PPO and residual solvent. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3872–3875, 2003
Iodine doping of poly(3‐undecylbithiophene) and its composites with polystyrene using supercritical carbon dioxide
Authors: Abbett Kimberly F. , Teja Amyn S. , Kowalik Janusz , Tolbert Laren
Published: October 2003

Partially doped conductive poly(3‐undecylbithiophene) and its composites with porous, crosslinked polystyrene were chemically doped with iodine using supercritical carbon dioxide to transport iodine to the conductive regions of the composite. The amount of iodine incorporated into the composite increased from 9.3 wt % at ambient conditions without carbon dioxide to 21.4 wt % in the presence of supercritical carbon dioxide. The conductivity of the composite increased by up to two orders of magnitude with iodine doping using supercritical carbon dioxide. The highest conductivity was obtained in samples treated at moderate temperatures and pressures (313 K and 20.7 MPa). © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3876–3881, 2003
Thermoreversible gelation of nitrocellulose solutions
Authors: Mao Ching‐Feng , Chen Cheng‐Ho
Published: October 2003

Thermoreversible gelation of concentrated solutions of nitrocellulose was examined. The sol–gel transition diagrams were established using the ball‐drop method. The critical gel concentrations (Cgel), defined as the lowest concentration for gelation to occur, are approximately proportional to the reciprocal of the molecular weight of nitrocellulose. In addition, the values of Cgel[η] lie in the concentrated regime where entanglement effects are present. These facts suggest that the entanglement of polymer chains is a necessary condition for the formation of nitrocellulose gels. Moreover, the association of polymer segments is identified as another factor affecting the gel stability. This is evidenced by both the enhancement of the gel stability in poor solvents and the large enthalpy of mixing at low temperatures. Because of the presence of the association, the number of polymer chains in a junction point is larger than two, which is the value predicted by assuming entanglements as the only factor responsible for gelation. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 4000–4008, 2003
New route to the preparation of carboxymethylchitosan hydrogels
Authors: Janvikul Wanida , Thavornyutikarn Boonlom
Published: October 2003

A new method to prepare CM–chitosan hydrogels was introduced with the use of steam. The procedure was simple and economical, with no toxic chemicals involved. The steam‐induced crosslinking of CM–chitosan sodium salt involved the –NH2 and –COONa groups, forming amide linkages (–CONH–), evidently supported by FTIR spectroscopy and other techniques. The hydrogels instantly imbibed a great deal of water. The degree of swelling (DS) of the hydrogels was found to be up to 36, depending on the harshness of steaming conditions used. Likewise, the coloration of the samples increased from light beige to brown with increasing temperature and duration of steam exposure. The overall efficiency of the steam method for the crosslinking of CM–chitosan sodium salt was quite high. The percentage weight loss was found to be less than 10 to obtain hydrogels with DS values around 20. No weight loss in the dry weight of the fractionated hydrogels was observed when the samples were steamed at 115°C or higher for 15 min or longer. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 4016–4020, 2003
Preparation of epoxy resin/silica hybrid composites for epoxy molding compounds
Authors: Liu Ying‐Ling , Lin Yu‐Lo , Chen Chih‐Ping , Jeng Ru‐Jong
Published: October 2003

Phenolic novolac/silica and cresol novolac epoxy/silica hybrids were prepared through in situ sol‐gel reaction of tetraethoxysilane (TEOS). The formed hybrids were utilized as a curing agent and an epoxy resin in epoxy curing compositions, respectively. Via the two‐step preparation route, the resulting epoxy resin/silica hybrid nanocomposites exhibited good thermal stability, high glass transition temperatures, and low coefficients of thermal expansion. High condensation degree of the condensed silica was observed with a high content of siloxane bridges, p > 85%, measured by 29Si NMR. The two‐step route also provides feasibility of preparation of epoxy resin/silica hybrid nanocomposites compatible with the current processes of manufacturing of epoxy molding compounds. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 4047–4053, 2003
Thermal characterizations of semi‐interpenetrating polymer networks composed of poly(ethylene oxide) and poly(N‐isopropylacrylamide)
Authors: Kim Seon Jeong , Lee Chang Kee , Lee Young Moo , Lee Kyu Back , Park Yong Doo , Kim Sun I.
Published: October 2003

Poly(N‐isopropylacrylamide) (PNIPAAm)/poly(ethylene oxide) (PEO) semi‐interpenetrating polymer networks (semi‐IPNs) synthesized by radical polymerization of N‐isopropylacrylamide (NIPAAm) in the presence of PEO. The thermal characterizations of the semi‐IPNs were investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dielectric analysis (DEA). The melting temperature (Tm) of semi‐IPNs appeared at around 60°C using DSC. DEA was employed to ascertain the glass transition temperature (Tg) and determine the activation energy (Ea) of semi‐IPNs. From the results of DEA, semi‐IPNs exhibited one Tg indicating the presence of phase separation in the semi‐IPN, and Tgs of semi‐IPNs were observed with increasing PNIPAAm content. The thermal decomposition of semi‐IPNa was investigated using TGA and appeared at around 370°C. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3922–3927, 2003
Compositional analysis of biodegradable polyphosphoester copolymers using nmr spectroscopic methods
Authors: Chaubal Mahesh V. , Wang Bing , Su Geraldine , Zhao Zhong
Published: October 2003

The chemical composition and quantitative molar ratios among all components of biodegradable polyphosphoester copolymers of DL‐lactide and ethylphosphate were determined by a comprehensive set of NMR spectroscopic methods. The polyphosphoester copolymers studied were synthesized using condensation polymerization of oligomeric DL‐lactide prepolymers and ethyl dichlorophosphate. Conclusive identification of the chemical shift patterns of all functional groups in the copolymers required additional NMR methods such as 31P‐NMR and two‐dimensional 1H–1H COSY NMR, in addition to the synthesis and comparative NMR analysis of model compounds possessing identical phosphoester linkages in the polyphosphoester copolymers. For the polymers synthesized using the bulk polycondensation process, 1H–1H COSY NMR analysis revealed the presence of a small amount of side products that were undetected by 1H‐NMR alone. These side reactions most likely occurred between the pendant ethoxy group of the phosphoesters and the hydrogen chloride gas generated in the bulk polycondensation process. 31P‐NMR spectra of the copolymers revealed a consistent triple‐peak pattern characteristic of phosphoesters linked to a racemic mixture of D,L‐lactides. These results offered new insight into the side reactions occurring in bulk polymerization of polyphosphoesters and provided a powerful tool of characterizing complex biodegradable polymers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 4021–4031, 2003
Mometasone furoate degradation and metabolism in human biological fluids and tissues
Authors: Teng Xiao Wei , Cutler David J. , Davies Neal M.
Published: October 2003

The in vitro metabolic and non‐metabolic degradation kinetics of mometasone furoate (MF) was investigated in selected human biological fluids and subcellular fractions of tissues. Qualitative and quantitative differences in transformation profiles of MF were observed among human biological media. Degradation was the major event in plasma and urine with four new degradation products identified; A: 21‐chloro‐17α‐hydroxy‐16α‐methyl‐9β,11β‐oxidopregna‐1,4‐diene‐3,20‐dione 17‐(2‐furoate), B: 9α,21β‐dichloro‐11β,21α‐dihydroxy‐16α‐methylpregna‐1,4,17,20‐tetraen‐3‐one 21‐(2‐furoate), C: 21β‐chloro‐21α‐hydroxy‐16α‐methyl‐9β,11β‐oxidopregna‐1,4,17,20‐tetraen‐3‐one 21‐(2‐furoate), and D: 21‐chloro‐17α‐hydroxy‐16α‐methyl‐9β,11β‐oxidopregna‐1,4‐diene‐3,20‐dione. A, B and C were predominant and D was minor in plasma while A and C were predominant in urine. Hydrolysis of the 17‐ester bond of MF was not a major event in plasma. The turnover of MF in plasma was faster than that in phosphate buffers of pH 7.4.

Metabolism of MF occurred primarily and rapidly in liver, appreciably in intestine, but negligibly in in vitro lung tissue. While 6β‐hydroxylation was a major metabolic pathway for MF in microsomes of both human liver and intestine, other parallel and subsequent metabolism pathways could also be involved. If these degradation and metabolic products are also formed and active in humans in vivo, both MF and its ‘active’ products need to be taken into account when determining the systemic bioavailability of MF and in establishing concentration‐effect relationships with this drug. Copyright © 2003 John Wiley & Sons, Ltd.
Pharmacokinetic characterization of a human immunodeficiency virus protease inhibitor, saquinavir, during ethanol intake in rats
Authors: Shibata Nobuhito , Kageyama Michiharu , Kishida Tomoyuki , Kimura Keisuke , Yoshikawa Yukako , Kuwahara Takeshi , Toh Jyunichiro , Shirasaka Takuma , Takada Kanji
Published: October 2003

Throughout therapeutic drug monitoring of human immunodeficiency virus (HIV) protease inhibitors in HIV‐infected patients, it was found that plasma concentrations of saquinavir (SQV) were reduced in patients who had a habit of alcohol intake during double protease therapy with SQV and ritonavir (RTV). This study confirmed the pharmacokinetic profiles of SQV during ethanol intake in rats. After oral administration of SQV alone (20 mg/kg) in rats prepared by free access to 15% ethanol solution for 14 days (day 14 rats), the area under the concentration vs time curves (AUC) showed a significant decrease (p<0.01) in comparison with control rats from 0.78±0.10 to 0.38±0.03 μg h/ml. For intravenous administration of SQV alone (5 mg/kg) to day 14 rats, the total body clearance increased significantly by 1.4‐fold (p<0.05), whereas for intracolonic administration of SQV alone, no significant differences in the values of pharmacokinetic parameters were found between control and day 14 rats. With RTV, which has the strongest inhibitory effect on the CYP3A enzyme of the current HIV protease inhibitors, the AUC values of SQV at RTV doses of 2 and 20 mg/kg in day 14 rats also decreased significantly (p<0.01) from 1.30±0.06 to 0.57±0.05 μg h/ml and from 17.63±1.66 to 4.18±0.94 μg h/ml, respectively, indicating that the degree of the decrease of AUC values after oral administration with RTV after ethanol intake was larger than the mono‐therapy with SQV. This study showed that ethanol‐intake decreases the bioavailability of SQV after oral administration alone or with RTV. These observations provide useful information for the treatment of HIV‐infected patients when they receive a combination therapy with SQV and RTV, and arouse attention for the effects of alcohol intake. Copyright © 2003 John Wiley & Sons, Ltd.
Pharmacokinetics and tissue distribution of uraemic indoxyl sulphate in rats
Authors: Deguchi Tsuneo , Nakamura Mikio , Tsutsumi Yasuhiro , Suenaga Ayaka , Otagiri Masaki
Published: October 2003

The purpose of the present study was to examine the pharmacokinetic properties of indoxyl sulphate, a harmful uraemic toxin that accumulates during chronic renal failure. The pharmacokinetics and tissue distribution of indoxyl sulphate were examined in normal and 5/6 nephrectomized (CRF) rats. The uptake process of indoxyl sulphate by rat renal cortical slices in vitro was also investigated. Endogenous indoxyl sulphate was found to be mainly distributed in the kidney. The rate of elimination of indoxyl sulphate from plasma was lower in CRF rats compared with sham‐operated rats. The majority of intact indoxyl sulphate was excreted in the urine. In renal cortical slice experiments, uptake of indoxyl sulphate was a saturable process with a Km of 43.0 μm. Furthermore, sulphate conjugates, such as oestrone sulphate and dehydroepiandrosterone sulphate, inhibited the uptake of indoxyl sulphate to a greater extent than PAH. Thus, indoxyl sulphate is primarily eliminated from the plasma via the kidney by active tubular secretion, and renal uptake of indoxyl sulphate appears to be mediated by an organic anion transport system with a high affinity for oestrone sulphate and dehydroepiandrosterone sulphate. Copyright © 2003 John Wiley & Sons, Ltd.
Acetyl‐L‐carnitine permeability across the blood–brain barrier and involvement of carnitine transporter OCTN2
Authors: Inano Akihiro , Sai Yoshimichi , Nikaido Hiroko , Hasimoto Noriyoshi , Asano Masahide , Tsuji Akira , Tamai Ikumi
Published: October 2003

OCTN2 (SLC22A5), an organic cation/carnitine transporter, is widely distributed throughout the body, including the brain. In the present study, the involvement of OCTN2 in acetyl‐L‐carnitine (ALCAR) permeation across the blood–brain barrier (BBB) was examined using a microdialysis method in mouse. OCTN2 function was examined by comparison of wild‐type mice with jvs mice, which express defective OCTN2 and are considered a model for primary systemic carnitine deficiency. Zero‐net‐flux method analysis indicated higher in vivo recovery of ALCAR and lower physiological ALCAR concentration in thalamus extracellular fluid (ECF) in jvs mice compared with wild‐type mice. Externally added ALCAR showed significantly slower initial uptake across the BBB in jvs mouse. These results indicated that OCTN2 is functionally involved in ALCAR transfer across the BBB. Total radioactivity in ECF after i.v. administration of radiolabelled ALCAR remained constant for the rest of the experimental period. Accordingly, our results indicate that ALCAR is transported from blood to brain ECF by OCTN2 at least in part, and its concentration in brain ECF is regulated by other events such as protein binding and anabolic reactions in the brain, as well as by transport across the BBB. Copyright © 2003 John Wiley & Sons, Ltd.
Non‐thermal bacterial inactivation with dense CO2
Authors: Spilimbergo S. , Bertucco A.
Published: October 2003

The use of CO2 under pressure (dense CO2) is one of the most promising techniques to achieve cold pasteurization and/or sterilization of liquid and solid materials, and is likely to replace or partially substitute currently and widely applied thermal processes. Although the ability of CO2 to inactivate microorganisms has been known since the 1950's, only within the last 15 years it has received special attention, and the scientific and economic interest towards practical applications is presently growing more and more. Here we collect and discuss the relevant current knowledge about the potentials of dense CO2 as a non‐thermal technology in the field of microbial inactivation. We summarize the state of the art, including definitions, description of the equipment, relevant applications, in both simple suspensions and complex media, for the treatment of a wide range of microorganisms in both liquid and solid substrates. Finally, we also summarize and discuss the different hypotheses about the mechanisms of inactivation © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 627–638, 2003.
Continuous fermentative hydrogen production from a wheat starch co‐product by mixed microflora
Authors: Hussy I. , Hawkes F.R. , Dinsdale R. , Hawkes D.L.
Published: October 2003

For the transition to the hydrogen economy, hydrogen must be produced sustainably, e.g., by the fermentation of agricultural material. Continuous fermentative production of hydrogen from an insoluble substrate in nonsterile conditions is yet to be reported. In this study hydrogen production using mixed microflora from heat‐treated digested sewage sludge in nonsterile conditions from a particulate co‐product of the wheat flour industry (7.5 g L−1 total hexose) at 18‐ and 12‐hour hydraulic retention times, pH 4.5 and 5.2, 30°C and 35°C was examined. In continuous operation, hydrogen yields of approximately 1.3 moles hydrogen/mole hexose consumed were obtained, but decreased if acetate or propionate levels rose, indicating metabolism shifted towards hydrogen consumption by homoacetogenesis or propionate producers. These shifts occurred both at pH 4.5 and 5.2. Sparging the reactor with nitrogen to reduce hydrogen in the off‐gas from 50% to 7% gave stable operation with a hydrogen yield of 1.9 moles hydrogen /mole hexose consumed over an 18‐day period. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 619–626, 2003.
Starch fermentation by recombinant saccharomyces cerevisiae strains expressing the α‐amylase and glucoamylase genes from lipomyces kononenkoae and saccharomycopsis fibuligera
Authors: Eksteen J.M. , van Rensburg P. , Cordero Otero R.R. , Pretorius I.S.
Published: October 2003

Lipomyces kononenkoae and Saccharomycopsis fibuligera possess highly efficient α‐amylase and/or glucoamylase activities that enable both of these yeasts to utilize raw starch as a carbon source. Eight constructs containing the L. kononenkoae α‐amylase genes (LKA1 and LKA2), and the S. fibuligera α‐amylase (SFA1) and glucoamylase (SFG1) genes were prepared. The first set of constructs comprised four single gene cassettes each containing one of the individual amylase coding sequences (LKA1, LKA2, SFA1 or SFG1) under the control of the phosphoglycerate kinase gene (PGK1) promoter and terminator, while the second set comprised two single cassettes containing SFA1 and SFG1 linked to their respective native promoters and terminators. The third set of constructs consisted of two double‐gene cassettes, one containing LKA1 plus LKA2 under the control of the PGK1 promoter and terminator, and the other SFA1 plus SFG1 controlled by their respective native promoters and terminators. These constructs were transformed into a laboratory strain Saccharomyces cerevisiae (Σ1278b). Southern‐blot analysis confirmed the stable integration of the different gene constructs into the S. cerevisiae genome and plate assays revealed amylolytic activity. The strain expressing LKA1 and LKA2 resulted in the highest levels of α‐amylase activity in liquid media. This strain was also the most efficient at starch utilization in batch fermentations, utilizing 80% of the available starch and producing 0.61g/100 mL of ethanol after 6 days of fermentation. The strain expressing SFG1 under the control of the PGK1 expression cassette gave the highest levels of glucoamylase activity. It was shown that the co‐expression of these heterologous α‐amylase and glucoamylase genes enhance starch degradation additively in S. cerevisiae. This study has resulted in progress towards laying the foundation for the possible development of efficient starch‐degrading S. cerevisiae strains that could eventually be used in consolidated bioprocessing, and in the brewing, whisky, and biofuel industries. © 2003 Wiley Periodicals, Inc. Biotechnol Bioeng 84: 639–646, 2003.