bluuebunny/crossref_metadata_2025 huggingface dataset:
Malignancies in the acquired immunodeficiency syndrome
Authors: Tucker J. Allan
Published: April 2005

Malignancies frequently arise in patients infected with human immunodeficiency virus (HIV), including those patients classified as having the acquired immunodeficiency syndrome (AIDS). Currently, Kaposi's sarcoma and certain types of lymphoma are considered to develop as a result of HIV infection, and other cancers have also been reported in these patients. For the most part, ultrastructural study of HIV‐associated malignancies has been limited to Kaposi's sarcoma; the ultrastructural features of the epidemic form of this disease are generally the same as those of the classical form. The occurrence of these cancers in HIV‐infected individuals appears to be related to the immunodeficiency caused by this virus, but the basic etiologic mechanisms remain unknown. In general, only palliative treatments are presently available for HIV‐associated malignancies.
Dynamic focussing for recording images from tilted samples in small‐spot scanning with a transmission electron microscope
Authors: Zemlin F.
Published: April 2005

For three‐dimensional electron microscopical structure research the specimen must be imaged in a tilted position. Specimen tilt is also often needed to achieve an optimal molecular packing orientation. The tilt with respect to the optical axis causes a defocus gradient alongside the imaged area and thus entails the following complications: (1) The phase‐contrast transfer function fades for strong defocus; (2) the Fourier coefficients are split; and (3) the signal‐to‐noise ratio cannot be enhanced by simple averaging. An image procedure with small‐spot scanning and simultaneous defocus compensation is proposed which helps to reduce these problems.
Electron diffraction and diffraction contrast imaging of thin organic films
Authors: Hui Sek‐wen
Published: April 2005

The applications of electron diffraction and diffraction contrast electron microscopy with which to study the structure and dynamics of organic thin films are discussed. The techniques of making thin film deposits on substrates and of forming free‐standing thin films over holes on the substrate are described. Selected area electron diffraction and diffraction contrast imaging techniques for thin film studies are elaborated, and examples are given. Methods to reduce radiation damage and environmental protection of the thin film specimen are outlined.

The interpretation of electron diffraction and imaging data is given for three cases: (1) The effects of film tilting and molecular tilting (with respect to the film plane) are examined. (2) The detection of phase transition is illustrated. (3) The use of labels to mark film domains is shown together with the measurement of dynamic movement.
High‐resolution imaging of organic crystals
Authors: Fryer J. R.
Published: April 2005

The history of high‐resolution imaging of organic crystals is summarized, followed by a discussion of radiation damage which reflects current thinking. Methods of specimen preparation and the experimental techniques for high‐resolution imaging are described. The results show the application of these techniques to aromatic hydrocarbons, phthalocyanines, and linear‐chain aliphatic molecules. Artefacts and image interpretation are also discussed.
Direct observation of molecular images of lanthanide phthalocyanines: III. Structural defects
Authors: Zhang W. P. , Kuo K. H. , Dorset D. L. , Hou Y. F. , Ni J. Z.
Published: April 2005

The crystal imperfections in thin films of lanthanide phthalocyanines (LnPc2H, Ln = Nd, Tb, Er, Tm, Yb, and Lu) grown epitaxially on KCl have been ovserved by molecular imaging. Grain and twin boundaries, stacking faults, point defects, vacancies, mosaic structures, and sometimes even some amorphous islands exist in the well‐crystallized specimens. Combined with the results reported earlier, the packing characteristics of planar LnPc2H molecules can be well understood.
Early events of electroporation‐mediated intramuscular DNA vaccination potentiate Th1‐directed immune responses
Authors: Grønevik Eirik , Mathiesen Iacob , Lømo Terje
Published: April 2005

Background

Application of electrical pulses after DNA injection into muscle increases expression of the encoded genes, and is shown to improve antigen‐specific immune responses when used for DNA vaccination. In addition, electroporation causes tissue injury and inflammatory reactions. Together with immune stimulatory motifs in the injected DNA these factors may potentiate the immune response by acting as adjuvants for the antigen. Here, we have examined the role of these factors in promoting the efficiency of DNA vaccination.

Methods

We injected a plasmid DNA vector containing the gene Ag85B from M. tuberculosis into mouse quadriceps muscles followed by electroporation. Ag85B was under control of a Tet‐responsive promoter, and was expressed either immediately or up to 28 days later by administrating doxycycline to the mice. Delayed expression was combined with injection of non‐coding DNA or saline with or without electroporation to examine the ability of these factors to enhance the Ag85B‐specific antibody response in the blood and cellular responses in the spleen. Blood samples were analysed with ELISA, while the number of Ag85B‐specific IFN‐γ‐ and IL‐4‐producing spleenocytes was analysed with ELISpot.

Results

Delaying Ag85B expression by 5 or 28 days caused lower anti‐Ag85B‐specific IgG2a levels. In contrast, the IgG1 antibody response was not significantly affected. Injection of non‐coding DNA followed by electroporation moderately increased the IgG2a response. Delaying the Ag85B expression by 28 days reduced the average number of Ag85B‐specific IFN‐γ‐producing spleenocytes by over 60%. No significant change in the number of IL‐4‐producing Ag85B‐specific spleenocytes was observed.

Conclusions

These results suggest that DNA and electroporation per se may act as good adjuvants in promoting efficient Th1‐directed responses during DNA vaccination. Copyright © 2005 John Wiley & Sons, Ltd.
Ultrastructural study of two kinds of muscle in sea anemones: The existence of fast and slow muscles
Authors: Amerongen H. M. , Peteya D. J.
Published: April 2005

The sea anemones studied have two morphological types of muscle fiber. Types A and B are distinguishable on the basis of myofilament patterns, size of fibers, responses to fixation, and staining with methylene blue. Observation of the muscle in both resting and contracted states has shown that the two types do not result from differences in contraction state of the muscle. The fine structural characteristics distinguishing A and B fibers are similar to those which distinguish fast and slow muscle fibers in higher animals. The distribution of A and B fibers in Stomphia and Aiptasia is consistent with the distribution of fast and slow muscles in these two species. It is proposed that the A and B fibers represent two morphologically distinct kinds of smooth muscle, and that the capacity for fast and slow contraction in the muscles of Stomphia and Aiptasia, and possibly in all actinians, is due to morphological differentiation in the muscle system.
Morphology of the abdominal skeleton and muscles of the mosquito, Culiseta inornata (Williston) (Diptera: Culicidae)
Authors: Owen William B.
Published: April 2005

The morphology of the abdominal skeleton and muscles of the adult mosquito is incompletely known. The objectives of this study were to investigate these features in a common species, Culiseta inornata (Williston). Preserved specimens were stained lightly with methylene blue and studied with a dissecting microscope at 70 × and lower. The sclerites of the pregenital segements are best developed in segment II. The base of segment VIII in the male is narrow and semicircular in shape. This modification aids in rotation of the terminalia. Two new names are introduced for parts of the terminalia. Apodeme of sternum 9 is proposed for atrial plate of the female. Gonocoxital apodeme is a new term for a structure in the male. Both of these structures serve for attachement of muscles. Terms preferred for parts of the male terminalia are: (1) gonocoxite and gonostylus for the clasping organ; (2) paramere for the sclerotized plates on each side of and joined to the aedeagus; (3) sternum 10 for paraprocts. Sternum 10 is used because the occurrence of true paraprocts in the Nematocera is questionable. Thirty‐four muscles are illustrated, and the origin and insertion of each is described. Eighteen of the muscles are newly described for the mosquito. The rotational muscles of the male terminalia were identified. The results are presented in 21 text figures.
Avian scale development. VII. Normal keratinization follows abnormal morphogenesis of reticulate scales from the “scaleless” mutant
Authors: Sawyer Roger H. , Borg Thomas K.
Published: April 2005

The scutate scales are entirely missing in chick embryos homozygous for the gene, “scaleless.” Reticulate scales of this mutant are present; however, they have undergone abnormal morphogenesis into irregular mounds and crevices. The pattern of keratinization seen along the anterior metatarsus of normal embryos differs dramatically from that seen along the anterior metatarsus of scaleless embryos. In contrast, we find that the unique pattern of keratinization seen in the epidermal cells of normal reticulate scales is retained in mutant reticulate scales, even though these scales are morphologically abnormal. We believe that differences in the initial tissue interactions (which establish the inductive ability of the dermis) of these two types of scales are responsible for the differences seen in their responses to the scaleless gene. The pleiotropic nature of the scaleless gene is discussed.
Fetal tooth development and adult replacement in Dermophis mexicanus (Amphibia: Gymnophiona): Fields versus clones
Authors: Wake Marvalee H.
Published: April 2005

Teeth of fetuses of a caecilian, Dermophis mexicanus (Amphibia: Gymnophiona), show ontogenetic variation in crown structure from small, multidenticulate, and non‐pedicellate to larger, spoon‐shaped, pedicellate teeth with a single apical spike. Number of denticles decreases as enamel‐secreting cells mature. Numbers of teeth and of tooth rows increase ontogenetically. A fetal vomeropalatine set of teeth is present in D. mexicanus but absent in species previously examined. Teeth transitional to the adult shape and arrangement appear shortly before birth. The transition is correlated with birth, not fetal size. There is relatively little increase in numbers of teeth during the juvenile period. The pattern of development does not fully agree with either morphogenetic field theory or with clone theory, both as defined by Osborn ('78). Sequence of initiation is appropriate to either. Tooth shape changes agree with aspects of clone theory. Multiple rows of fetal teeth and the transition to adult follow field theory. Clone theory holds that patterns of development and shape are self‐regulated, field theory that they are controlled extrinsically. I suggest that substances regulating differentiation mediate early development, and hormones later development, including inception of adult teeth, and are comparable to “field substances” influencing primordia that originate according to clone theory. Components of both theories are appropriate to analyzing tooth development phenomena.
A commentary on muscle unit properties in cat hindlimb muscles
Authors: McDonagh Jennifer C. , Binder Marc D. , Reinking Robert M. , Stuart Douglas G.
Published: April 2005

A broad survey of muscle unit properties in 14 muscles of the cat hind limb is presented which emphasizes some general features of unit properties in mammalian muscles. A more detailed analysis of muscle unit properties in three muscles of the posterior compartment of the lower leg is then presented using Burke's tetrapartite (FF, FI or F (Int.), FR, and S) unit classification scheme. Our data on the properties of motor units in cat tibialis posterior (TP) have been compared to those generated by Burke and colleagues on units in flexor digitorum longus (FDL) and medial gastrocnemius (MG). In all three muscles, twitch contraction time was distinctly slower for type S units and specific tension outputs were substantially greater for type FF units than for type S units. The innervation ratios of type FR units were slightly lower than for type S units but the specific tension of the FR units was closer to FF units than to type S units. The FF units controlled 70–74% of the cumulative force output of each muscles, indicating a substantial capacity for powerful rapid contractions of all three of these muscles despite their differences in “size,” action, and force generation. Distinctive features of the three muscles included differences in the unit types' force producing capabilities and in the relative representation of “nonfatigable” type FR and S units in each muscle. In particular, TP is endowed with some unusually powerful type FF units and a high percentage (42%) of type S units. In contrast, FDL has units that develop relatively little force and an unusually high representation (56%) of type FR units. The possible relationships between these muscle features and their presumed role in posture and locomotion is discussed.
Transformation of the endostyle of the anadromous sea lamprey, Petromyzon marinus L., during metamorphosis. II. Electron microscopy
Authors: Wright Glenda M. , Youson John H.
Published: April 2005

Electron microscopy was used to follow the transformation of the endostyle to a thyroid gland in the anadromous sea lamprey, Petromyzon marinus L., throughout metamorphosis (stages 1–7). Transformation of the larval (ammocoete) endostyle begins at the first signs of external change (stages 1–2), and the adult form of the gland is reached by stage 5. Only slight modifications of the gland accompany further development to the end of metamorphosis.

Development of the thyroid gland involves degeneration, proliferation, and reorganization of the cells in the endostyle, and changes in their fine structure. Ultrastructural changes during early stages are most obvious in the type 1 cells that make up the shrinking glandular tracts, and involves the accumulation of cytoplasmic microfilaments and a variety of cytoplasmic inclusions. The glandular tracts and their cells gradually disappear through autolysis and, apparently, through phagocytosis by neighboring epithelial cells and macrophages. Although the fine structure of the type 2, 3, 4, and 5 cells is not altered in the early stages, by stage 3, many of these cells become either vacuolated, undergo autolysis, or are extruded. Phagocytosis of some of each of these cell types likely occurs.

Thyroid follicles are first observed during stage 4. Some of their lumina seem to arise from the accumulation of material in intercellular spaces and from vacuoles among cell clusters. Other lumina may represent a portion of the original lumen of the endostyle. Many follicles appear to be comprised of cells with cytological characteristics similar to those of larval cell types 3 and 2c. Some of the other larval cell types, such as type 5, may also be involved. In young adult lampreys follicles are composed of cuboidal to columnar cells that lack the dilated cisternae of rough endoplasmic reticulum seen in follicular cells of higher vertebrates. Dense collagenous connective tissue surrounding the follicles contains relatively few blood vessels.

The transformation process described may have some relevance to our understanding of the development and evolution of the vertebrate thyroid gland.
D‐β‐hydroxybutyrate is neuroprotective against hypoxia in serum‐free hippocampal primary cultures
Authors: Masuda R. , Monahan J.W. , Kashiwaya Y.
Published: April 2005

Hypoxia decreased survival of cultured rat primary hippocampal neurons in a time dependent manner. Addition of 4 mM NaD‐β‐hydroxybutyrate (bHB), a ketone body, protected the cells for 2 hr and maintained the increase in survival compared to that of controls for up to 6 hr. Trypan blue exclusion indicated that acute cell death was reduced markedly after 2‐hr exposure to hypoxia in the bHB‐treated group. The presence of bHB also decreased the number of neurons exhibiting condensed nuclei visualized by propidium iodide, indicative of apoptosis. The mitochondrial transmembrane potential (Em/c) was maintained for up to 2 hr exposure to hypoxia in the bHB‐treated group, whereas the potential in the control group was decreased. Furthermore, cytochrome C release, caspase‐3 activation, and poly (ADP‐ribose) polymerase (PARP) cleavage were decreased in the bHB‐treated group for the first 2 hr of exposure. These findings indicate that ketone bodies may be a candidate for widening the therapeutic window before thrombolytic therapy and at the same time decreasing apoptotic damage in the ischemic penumbra. © 2005 Wiley‐Liss, Inc.
Caspases‐2, ‐3, and ‐7 are involved in thapsigargin‐induced apoptosis of SH‐SY5Y neuroblastoma cells
Authors: Dahmer Mary K.
Published: April 2005

Caspase‐2 has been reported to play a role in the cell death observed under a number of different conditions; however, it is unclear whether caspase‐2 plays a role in cell death triggered by endoplasmic reticulum (ER) stress. The purpose of this study was to determine whether caspase‐2 is involved in SH‐SY5Y neuroblastoma cell death caused by thapsigargin‐induced ER stress. Thapsigargin treatment (1 μM, 16 hr) stimulated the proteolytic processing of caspases‐2, ‐3, and ‐7, suggesting that these caspases are activated by ER stress. The role of these caspases in thapsigargin‐induced cell death was examined by using cell‐permeable caspase inhibitors. In the absence of pretreatment with caspase inhibitors, thapsigargin (0.1 μM, 20 hr) reduced the number of viable cells to 53.9% ± 3.3% of starting‐time control. Pretreatment for 90 min with either the pan‐caspase inhibitor Z‐VAD‐FMK or the caspase‐2‐selective inhibitor Z‐VDVAD‐FMK inhibited thapsigargin‐stimulated cell death, resulting in the number of viable cells being 115.6% ± 5.3% (P < 0.001) and 69.3% ± 2.9% (P < 0.01), respectively, of starting‐time control. Neither the caspase‐3‐ and ‐7‐selective inhibitor Z‐DEVD‐FMK nor the caspase‐9‐selective inhibitor Z‐LEHD‐FMK significantly affected thapsigargin‐stimulated cell death. An anticaspase‐12‐reactive protein was also identified in SH‐SY5Y cells, but thapsigargin had no effect on proteolysis of this protein. These data demonstrate that caspases‐2, ‐3, and ‐7 are involved in ER stress‐mediated death of SH‐SY5Y cells. © 2005 Wiley‐Liss, Inc.
Compact ring resonators using negative‐refractive‐index microstrip line
Authors: Scher Aaron D. , Rodenbeck Christopher T. , Chang Kai
Published: April 2005

A compact ring resonator using a negative‐refractive‐index microstrip line is presented. It is demonstrated that the ring structure resonates even with an inner diameter of zero. The total circumference of the proposed resonator is reduced by 84%, as compared to a conventional ring resonator at 1.2 GHz. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 294–295, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20799
Comparison of the temperature dependence of different types of Bragg gratings
Authors: Lima M. J. N. , Nogueira R. N. , Silva J. C. C. , Teixeira A. L. J. , André P. S. B. , da Rocha J. R. F. , Kalinowski H. J. , Pinto J. L.
Published: April 2005

We investigate and compare the thermal stability and sensitivity of fiber Bragg gratings (FBGs) obtained from different growth mechanisms, including the well‐known types I, IA, IIA and a new abnormal regime, written in high‐Germanium‐doped optical fiber. The highest stability and sensitivity values are achieved for the type IIA grating. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 305–307, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20804
A novel compact miniaturized wideband microstrip bandpass filters with dual‐mode ring resonators
Authors: Chen Chu‐Yu , Hsu Cheng‐Ying , Lin Sung‐Fong
Published: April 2005

This paper presents a novel, compact, low‐insertion‐loss, sharp‐rejection, wideband microstrip bandpass filter. The filter is based on a ring resonator with direct‐connected orthogonal feed lines, and uses two stepped‐impedance open stubs to construct a wideband passband with two sharp stopbands. The unit cell of the ring resonators is easily cascaded and also has the feature of a compact structure. The filter is designed to reduce interference in full‐duplex systems for satellite communications. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 312–315, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20807
Small perforated shorted‐patch antenna
Authors: Kan H. K. , Waterhouse R. B. , Pavlickovski D.
Published: April 2005

We present a patch antenna that is small in area as a result of combining two size‐reduction procedures: using a single shorting pin and perforating the patch conductor. The new printed antenna is 30% smaller in area than a conventional shorted (single‐post) patch and 93% smaller than a traditional probe‐fed patch antenna, all designed on the same material. The measured 10‐dB return loss of the shorted perforated patch is 8.1% and the gain varies from 0.5 to 1 dBi across this bandwidth. The overall size of the antenna (including ground plane) is 0.13λ0 × 0.12λ0 × 0.07λ0. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 319–321, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20810
Study of microstrip mode in RF on‐wafer probes
Authors: Safwat Amr M. E.
Published: April 2005

An RF on‐wafer probe is simulated using commercial 3D simulation software. The two‐port simulated S‐parameters are found to be in a good agreement with the experimental data. The model is extended to study the microstrip‐mode effects in a typical RF on‐wafer probe. The microstrip mode is studied as the mode between the probe coax outer conductor and the wafer chuck. The microstrip‐mode reflection coefficient looking into the probe tips is determined for the first time. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 324–328, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20812
Wideband folded‐patch antennas fed by L‐shaped probe
Authors: Yang Steven S. L. , Luk K. M.
Published: April 2005

Simple folded‐patch antennas fed by an L‐shape probe are designed and studied experimentally. This simple antenna structure with thick air substrate attains a projection‐length reduction of about 30% with reference to the conventional half‐wave patch antenna. This antenna attains an impedance bandwidth of 35% and a gain of 6 dBi. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 352–355, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20821
High char‐yielding poly[acrylonitrile‐co‐(itaconic acid)‐co‐(methyl acrylate)]: synthesis and properties
Authors: Devasia Renjith , Reghunadhan Nair CP , Sivadasan P , Ninan KN
Published: April 2005

Polyacrylonitrile terpolymers of various compositions consisting of acrylonitrile (AN), itaconic acid (IA) and methyl acrylate (MA) were synthesized by solution polymerization in dimethylsulfoxide. Increase in concentration of either IA or MA retarded the overall polymerization rate and the polymer molecular weight. The system consisting of AN + MA and varying IA concentration was more prone to retardation in comparison with the system composed of AN + IA with variable MA concentration. The retardation factors were quantified. Minor quantities of MA boost the reactivity of IA in the terpolymer system. The terpolymer was richer in MA vis‐à‐vis the feed. The thermal characteristics of the terpolymer were examined as a function of its composition. In contrast to the copolymer of AN and IA requiring 1–1.5 mol% IA, the terpolymer required an IA content of approximately 2.5 mol% for optimum thermal stability. The polymer with 90 mol% AN, 2.5 mol% IA and 7.5 mol% MA exhibited reasonably good char‐forming characteristics and thermal stability. The overall crystallinity and crystallite size of the polymers were found to decrease on incorporation of the comonomers. The ‘aromatization index’ of the copolymer increased with the temperature of pyrolysis through re‐organization of the tetrahydropyridine ladder structure. Copyright © 2005 Society of Chemical Industry
Synthesis and characterization of new thermally stable poly(ester‐imide)s derived from 2,2′‐bis(4‐trimellitimidophenoxy)biphenyl and 2,2′‐bis(4‐trimellitimidophenoxy)‐1,1′‐binaphthyl and various aromatic dihydroxy compounds
Authors: Behniafar Hossein , Habibian Sedigheh
Published: April 2005

A series of new alternating aromatic poly(ester‐imide)s were prepared by the polycondensation of the preformed imide ring‐containing diacids, 2,2′‐bis(4‐trimellitimidophenoxy)biphenyl (2a) and 2,2′‐bis(4‐trimellitimidophenoxy)‐1,1′‐binaphthyl (2b) with various aromatic dihydroxy compounds in the presence of pyridine and lithium chloride. A model compound (3) was also prepared by the reaction of 2b with phenol, its synthesis permitting an optimization of polymerization conditions. Poly(ester‐imides) were fully characterized by FTIR, UV‐vis and NMR spectroscopy. Both biphenylene‐ and binaphthylene‐based poly(ester‐imide)s exhibited excellent solubility in common organic solvents such as tetrahydrofuran, m‐cresol, pyridine and dichloromethane. However, binaphthylene‐based poly(ester‐imide)s were more soluble than those of biphenylene‐based polymers in highly polar organic solvents, including N‐methyl‐2‐pyrrolidone, N,N‐dimethylacetamide, N,N‐dimethylformamide and dimethyl sulfoxide. From differential scanning calorimetry thermograms, the polymers showed glass‐transition temperatures between 261 and 315 °C. Thermal behaviour of the polymers obtained was characterized by thermogravimetric analysis, and the 10 % weight loss temperatures of the poly(ester‐imide)s was in the range 449–491 °C in nitrogen. Furthermore, crystallinity of the polymers was estimated by means of wide‐angle X‐ray diffraction. The resultant poly(ester‐imide)s exhibited nearly an amorphous nature, except poly(ester‐imide)s derived from hydroquinone and 4,4′‐dihydroxybiphenyl. In general, polymers containing binaphthyl units showed higher thermal stability but lower crystallinity than polymers containing biphenyl units. Copyright © 2005 Society of Chemical Industry
Oxidative degradation of polyaniline during the chemical oxidative polymerization of aniline in aqueous methanol medium
Authors: Chakraborty Mukut , Mandal Broja M , Mukherjee Dulal C
Published: April 2005

The course of chemical oxidative polymerization of aniline using ammonium persulfate as the initiator in acidic (1 M HCl) aqueous methanol (30 to 70 vol%) was studied spectrophotometrically. It was found that at temperatures greater than about 10 °C the reaction leads to degradation of polyaniline, the effect being greater with increasing methanol concentration. This is quite unlike the situation in aqueous ethanol where the product is the usual emeraldine hydrochloride form of polyaniline. Copyright © 2005 Society of Chemical Industry
Effects of monomer addition sequences on the properties of silicon‐containing copolyimides
Authors: Ren Li , Li GL , Shen Jiarui , Jia Demin
Published: April 2005

A series of silicon‐containing copolyimides was synthesized by the reaction of 4,4′‐diaminodiphenylmethane (DDM) with 1,4‐bis(3‐aminopropyldimethylsilyl) benzene (BisB) and pyromellitic dianhydride (PMDA). The synthesis reactions of the copoly(amic acid)s were carried out by three different monomer addition sequences under different molar ratios of BisB to DDM. The results obtained show that the viscosity of the poly(amic acid) (PA) solution obtained by the addition sequence of DDM–PMDA–BisB is higher than those of the other two addition sequences (ie [DDM + BisB]–PMDA and BisB–PMDA–DDM) and decreases as the molar ratio of BisB to DDM increases. Copolyimides formed by different addition orders, but with the same BisB to DDM molar ratios, possess different properties, such as dielectric constant, water absorption and contact angle. All of these copolyimides were insoluble in common organic solvents such as N‐methyl‐2‐pyrrolidinone and tetrahydrofuran. Thermogravimetric analysis (TGA) show that the silicon‐containing copolyimides have excellent thermal properties and their decomposition temperatures for an 8 % weight loss decrease slightly as [BisB]/[DDM] increases. Copyright © 2005 Society of Chemical Industry
Characterization of the sorption of an anthranilate fungicide in soil using thermal analytical and mineralogical techniques
Authors: Kennedy Angela , Lopez‐Capel Elisa , Manning David AC , Wilkins Richard M
Published: April 2005

The sorption of pesticides to soil particles has implications for their distribution and fate in the soil environment. A batch equilibrium technique was used to investigate sorption of the fungicide AEC623892 to intact and hydrogen‐peroxide‐treated whole soils and several particle‐size fractions isolated from them. Sorption of AEC623892 to the soil as a whole was low. Kfoc values measured in the whole soils were 169.2 and 41.9 ml g−1 for Soil A and Soil B respectively. The highest values of Kfoc were measured in soil particle‐size fractions <53 µm (266.5 ml g−1 in the 2–20 µm fraction of Soil A; 471.9 ml g−1 in the 20–53 µm fraction of Soil B). Sorption was most irreversible in the 2–20 µm fractions. Overall, treatment of soil particle‐size fractions with hydrogen peroxide resulted in lower values of Kfoc (112.3 ml g−1 in Soil A whole soil and 30.9 ml g−1 in Soil B whole soil). In both soils, the maximum sorption among hydrogen‐peroxide‐treated samples was observed in the <2 µm fraction (166.6 and 311.0 ml g−1 for Soil A and Soil B, respectively). Investigation of the mineralogical composition of the soils suggested that the clay mineralogy (dominated by kaolinite and illite) is less likely to account for the differences in sorption observed than differences in the characteristics of the soil organic matter. Thermal analysis of the different soil fractions indicated that hydrogen peroxide treatment preferentially removed aliphatic fractions of organic matter, but had less effect on lignin‐like, aromatic fractions. Copyright © 2005 Society of Chemical Industry
Accurate vibrational spectra of methylpotassium using a hybrid CCSD(t)/b3LYP approach and a variational treatment
Authors: Gohaud Neil , Begue Didier , Pouchan Claude
Published: April 2005

We present the structural parameters and vibrational spectra of CH3K computed using a hybrid approach in which CCSD(T) equilibrium values and harmonic wavenumbers are coupled to B3LYP anharmonic cubic and quartic terms in the framework of our variational treatment recently developed and presented for CH3Li. The obtained results confirm the assignment of several observed bands but suggest some revision of experimental assignments, as well. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Quantum‐controlled NOT gate made of coupled polyacetylene chains
Authors: Vales Guimarães Paulo Henrique , E Silva Geraldo Magela
Published: April 2005

Two interacting polyacetylene chains are considered as a system for possible physical implementation of a quantum‐controlled NOT gate. The two mid‐gap level states of a pair of solitons on each chain act as the control and target qubits, respectively. The dynamics of these solitons is calculated using an extended SSH Hamiltonian. The time‐dependent Schrödinger equation and the equation of motion for the lattice displacements are numerically integrated. The energy levels of the system are controlled by impurities added to each chain and the interchain interaction. The dynamics of the system is analyzed under the application of an electric field, and its influence on the energy levels is determined. The quantum‐controlled NOT gate behavior is obtained by the correct configuration of impurities. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Relativistic Gaussian basis sets obtained with a polynomial version of the generator coordinate Dirac–Fock method: Ionization energies of some closed‐shell atomic systems
Authors: Haiduke R. L. A. , de Macedo L. G. M. , Barbosa R. C. , Morgon N. H. , da Silva A. B. F.
Published: April 2005

The purpose of this work is to analyze the relativistic Gaussian basis sets obtained with a recently developed polynomial version of the generator coordinate Dirac–Fock method. The atomic systems chosen to evaluate the basis sets are some alkaline earth and noble gas atoms: He, Be, Ne, Mg, Ar, and Ca. Hartree–Fock, relativistic, and electronic correlation contributions to the atomic total energy of the neutral and ionized atomic species were estimated using these relativistic Gaussian basis sets. The basis sets developed were able to attain energies that deviate at most by 0.47 and 0.65 mHartree, respectively, from numerical Hartree–Fock and Dirac–Fock–Coulomb results and are also competitive with fully optimized relativistic Gaussian basis sets of similar sizes. The electronic correlation energy contributions were obtained after two nonrelativistic calculations: a Hartree–Fock and a full quadratic configuration interaction, including single and double substitutions. The uncontracted basis sets obtained here along with polarization functions chosen to have equal exponents to selected functions already present in the original set were adequate in describing not only the neutral but also the highly ionized atomic species. The comparison of some calculated shell ionization energies with experimental results presented a maximum deviation of 3% (for a total of 15 ionization values ranging from 18 to 10,599 eV), reinforcing the quality of the basis sets developed in this work. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Is the vibrational optical activity of (R)‐[2H1, 2H2, 2H3]‐neopentane measurable?
Authors: Hug Werner , Haesler Jacques
Published: April 2005

The compound, (R)‐[2H1, 2H2, 2H3]‐neopentane, with its Td symmetric electron distribution, is the archetype of molecules that owe their chirality exclusively to an asymmetric distribution of the masses of their nuclei. It has nine rotamers, which fall into two classes, one where the interchange of hydrogen and deuterium nuclei leads to an identical rotamer, and one where it interconverts different rotamers. Ab initio computations show that individual rotamers have Raman optical activity (ROA) and vibrational circular dichroism (VCD) of the same size as ordinary chiral molecules. Dilution and cancelation for the experimentally accessible equilibrium mixture reduces ROA and VCD, but the simulation of spectra with realistic band shapes of the Voigt type shows that both remain measurable in the 700–1,400‐cm−1 range, where ROA and VCD have a close to mirror image appearance. In the CH‐ and CD‐stretch region, in contrast, the sign pattern of ROA and VCD is identical. This curious behavior appears to be a consequence of the differing influence of inertial contributions in the two spectral regions. If summed over all vibrations, ROA and VCD cancel neatly, as one expects from the Td symmetric electron distribution. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Subcellular compartmentalization of calcium‐dependent and calcium‐independent neutral proteases in brain
Authors: Baudry Michel , Dubrin Richard , Lynch Gary
Published: April 2005

In the present experiments, we studied the subcellular distribution of three types of extralysosomal, neutral proteolytic activities in rat telencephalon: (1) nonthiol proteases (NTP), (2) thiol proteases (TP), and (3) calcium‐activated thiol proteases (calpains I and II). Subcellular fractionation was performed by using conventional differential and sucrose‐gradient centrifugation techniques. The only significant proteolytic activity detected in crude homogenates could be assigned to calpain II, the high‐threshold calcium‐activated protease. Within the primary fractions prepared from the homogenates, the highest levels of calpain II were found in S3, or the soluble cytoplasmic fraction. Significant activity of the enzyme was also present in P2, the crude mitochondrial/synaptosomal fraction. In contrast, the specific activity of calpain I was greatest in P2 with somewhat lesser enzymatic activity in P1 and S3. Most of the calpain I in P2 was recovered after differential centrifugation through sucrose gradients and lysis of the resultant subfractions. In marked contrast, only a small percentage of the calpain II activity was recovered in the gradient bands. In all, calpain II appears to be predominantly localized in the soluble cytoplasmic compartment while the greatest concentrations of calpain I are found in the soluble components of small glial and neuronal processes (pinched off during homogenization) that constitute the P2 fraction.

The highest specific activity of the calcium‐independent proteases was obtained in P3, a fraction essentially devoid of calpain, with a secondary peak in P2. Subfractionation of P2 revealed that calcium‐independent TP in P2 was associated with mitochondria while the calcium‐independent NTP was more uniformly distributed across myelin, synaptosomes, and mitochondria. In all cases, calcium‐independent neutral proteases proved to be associated with membranes to a far greater degree than the calpains.

These results indicate that neutral proteases in brain are compartmentalized to a surprising degree and therefore are likely to be operating at different stages or aspects of extralysosomal protein degradation. The concentration of calpain I in the P2 fraction and synaptosomal subfractions provides a plausible explanation for the occurrence of partially digested structural proteins obtained in highly purified postsynaptic densities isolated from cerebral cortex.
Neurotensin receptor binding sites in monkey and human brain: Autoradiographic distribution and effects of 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine treatment
Authors: Quirion Rémi , Welner Sharon , Gauthier Serge , Bédard Paul
Published: April 2005

Neurotensin (NT) receptor binding sites were characterized and localized by using membrane binding assay and in vitro receptor autoradioraphy in monkey and human brain. Additionally, the effects of 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP) treatment on NT binding sites were investigated in monkey. [125I]Tyr3‐NT ([125I]NT) apparently binds to a single class of high‐affinity sites (Kd in nanomolar range) in both species. Ligand selectivity patterns strongly suggest that the structural requirement of both monkey and human brain NT receptors are very similar to those previously reported in other tissues, such as those of the rat brain and rat stomach. In monkey brain, [125I]NT binding sites are discretely distributed with high densities of sites found in the cingulate cortex, amygdala, hippocampus, ventral tegmental area, substantia nigra, and periaqueductal gray matter. A similar pattern is observed in the human brain. However, the laminar distribution of [125I]NT binding sites in cortex varies between monkey and human brain. In monkey brain, [125I]NT binding sites are mostly concentrated in deep cortical layers while the laminar distribution of NT sites changes with cortical areas in human brain.

The densities of [125I]NT binding sites are markedly decreased in the caudate, putamen, and substantia nigra in MPTP‐treated monkeys. These results suggest strong interactions between NT and dopaminergic systems in both monkey and human brain tissues.
Characterization of corticotropin‐releasing factor receptor‐mediated adenylate cyclase activity in the rat central nervous system
Authors: Battaglia George , Webster Elizabeth L. , De Souza Errol B.
Published: April 2005

We report here that corticotropin‐releasing factor (CRF) stimulates adenylate cyclase activity in the rat central nervous system (CNS). In frontoparietal cortex homogenates, the stimulation by CRF was dependent on time, temperature, tissue protein concentration, and guanine nucleotides. The rank order of potency for CRF analogs and fragments in stimulating adenylate cyclase activity [(Nle21,38) rat CRF > rat CRF ⋍ acetyl ovine CRF (4–41) ⋍ alpha helical ovine CRF > ovine CRF >> ovine CRF (1–39) ⋍ ovine CRF (7–41)] was consistent with their affinities for CRF receptors in the brain and their relative potencies in stimulating pituitary adrenocorticotropic hormone secretion in vitro. The putative CRF receptor antagonist, alpha helical ovine CRF (9–41), did not stimulate adenosine 3′,5′‐cyclic monophosphate (cAMP) production but was able to attenuate the stimulation by various concentrations of rat CRF. The regional distribution of 125I‐Tyro‐ovine CRF binding (olfactory bulb > frontoparietal cortex ⋍ cerebellum ⋍ hypothalamus > striatum ≥ midbrain > hippocampus ≥ spinal cord) did not correspond with the regional degree of CRF receptor‐mediated stimulation of adenylate cyclase (frontoparietal cortex > olfactory bulb ≥ cerebellum > midbrain ≥ hippocampus > striatum ⋍ hypothalamus > spinal cord). In addition, marked differences were observed in the ability of forskolin to potentiate CRF‐stimulated cAMP production in the various brain areas examined. In summary, these data demonstrat that at least one of the second‐messenger systems mediating the effects of CRF in the CNS involves stimulation of cAMP production and provides further support for a neurotransmitter role for this neuropeptide in the brain. Significant differences in the regulation of CRF‐stimulated cAMP production and the disparity between CRF receptor number and receptor‐mediated adenylate cyclase activity in discrete regions of the rat CNS suggest that some populations of CRF receptors in the brain may be functionally coupled to alternative signal transduction mechanisms.
Pacemaker potentials of serotonergic dorsal raphe neurons: Contribution of a low‐threshold Ca2+ conductance
Authors: Burlhis Theresa M. , Aghajanian George K.
Published: April 2005

Neurons of the dorsal raphe nucleus exhibit intrinsic pacemaker potentials (gradual interspike depolarizing ramps) enabling them to sustain spontaneous rhythmic activity in the absence of synaptic interactions. A depolarizing prepotential (PP) has been observed in these cells, which appears to trigger the spike toward the end of the pacemaker cycle. The purposes of this study, carried out in the rat dorsal raphe nucleus brain slice preparation, were to (1) determine the ionic nature of the PP, (2) investigate its time‐ and voltage‐dependent properties, and (3) investigate the possible modulation of the underlying conductance by the α1‐agonist phenylephrine and by serotonin (5‐HT), agents that modify dorsal raphe pacemaker activity. During intracellular recording under current clamp, PPs were completely and reversibly blocked by divalent cations indicating that Ca2+ carries a significant portion of the current causing the PPs. Ni2+ specifically inhibited the PP with no effect on high‐threshold (−40 mV) Ca2+ spikes or the Ca2+ activated K+ conductance in these neurons. Activation threshold for the PP was found to be approximately −60 mV. Priming by hyperpolarization allowed removal of inactivation (de‐inactivation) of the PP in a time‐ and voltage‐dependent manner, with maximal PPs accompanying hyperpolarizing pulses to −90 mV and the de‐inactivation beginning to occur between −65 and −75 mV. Single‐electrode voltage‐clamp experiments demonstrated a region of negative‐slope conductance between −60 and −50 mV, which corresponds to the range of PP activation. The results of this study are consistent with a lowthreshold Ca2+ conductance underlying the PP whose role is to enable the membrane potential to rebound to action potential threshold at the end of the pacemaker cycle; neither phenylephrine nor 5‐HT directly affected this inward current.
Selective methodologies for the synthesis of biologically active piperidinic compounds
Authors: Cossy Janine
Published: April 2005

The synthesis of optically active substituted piperidines has been achieved by using four different methodologies. The first one is an intramolecular nucleophilic displacement of activated alcohol moieties that was used to build up the piperidine ring of (−)‐prosophylline and (−)‐slaframine, and the second one is a ring‐closing metathesis of unsaturated amines which was employed in the synthesis of (+)‐sedamine and 4a,5‐dihydrostreptazoline. The third methodology is the α‐functionalization of N‐Boc piperidines which was particularly useful in the synthesis of argatroban, and the fourth one is a ring expansion of prolinols to 3‐chloropiperidines or 3‐hydroxypiperidines which was utilized to synthesize (−)‐paroxetine, (−)‐pseudoconhydrine, the piperidine ring of (−)‐velbanamine and (+)‐zamifenacin. © 2005 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 5: 70–80; 2005: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20035
Reactions of ion‐pair intermediates of solvolysis
Authors: Tsuji Yutaka , Richard John P.
Published: April 2005

The detection during solvolysis of competing signature reactions such as the racemization of a chiral substrate, or the scrambling of oxygen isotopes at the leaving group serves as evidence for a stepwise mechanism that proceeds through a reversibly formed ion‐pair intermediate. We have examined these signature reactions and determined the relative rates of competing solvolysis, isomerization, and racemization reactions of neutral ring‐substituted 1‐phenylethyl derivatives. These data were used to define the relative rate constants for partitioning of carbocation–anion pairs between dynamic processes such as reorganization of the ion pair within a solvent cage, and migration of the leaving group anion from the “top” to the “bottom” face of the planar carbocation. We present here a well‐defined picture of the dynamics of these reactions in the mostly aqueous solvent of 50/50 (v/v) trifluoroethanol/water. A more complicated problem is the description of the changes in the reaction energy profiles for solvolysis, isomerization, and racemization reactions that occur as one destabilizes the carbocation intermediate of the stepwise reaction. We have examined the signature isomerization and racemization reactions of a ring‐substituted 1‐phenylethyl derivative that reacts by a “borderline” mechanism. We suggest that the signature isomerization reaction may in fact follow a concerted mechanism that bypasses the putative carbocation–anion pair intermediate. © 2005 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 5: 94–106; 2005: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20038
Provider gender and moral reasoning: The politics of an “ethics of care”
Authors: Wertz Dorothy C.
Published: April 2005

Women constitute 35% of providers in genetics at the doctoral level. A survey of 682 geneticists in 19 nations showed that gender was the single most important determinant of ethical decision making. Women were less directive and more observant of patient autonomy than men. In the United States, women were twice as likely as men to accede to patient requests for prenatal diagnosis for sex selection. Women now constitute 30% of all medical students, about half of all obstetrical residents, and 94% of master's‐level genetic counselors. Evidence that women providers respond differently to some ethical problems suggests that in the future, as more women enter the field, provider‐patient relationships may become more egalitarian.