bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Angola black‐and‐white colobus (Colobus angolensis palliatus) in Kenya: historical range contraction and current conservation status
Authors: Anderson J. , Rowcliffe J.M. , Cowlishaw G. 
Published: January 2007

AbstractThe Angola black‐and‐white colobus (Colobus angolensis palliatus) is a flagship species for Kenya's coastal forests, a global biodiversity hotspot and a region for “priority” conservation investment. This study provides the first evaluation of colobus distribution, status, and current threats within its Kenyan range: the southern coastal District of Kwale. Line transect and sweep count surveys were carried out between July and November of 2001, covering 25,514 ha of coastal forest within 124 forest fragments. A total of 55 colobus populations were located, with total Kenyan C. a. palliatus population estimates ranging between 3,100 and 5,000 individuals (560–900 groups). The Shimba Hills National Reserve protects both the largest forest and largest colobus population in the District. A total of 3,000 ha of coastal forest (12%) still remain unprotected and provide critical habitat for over 17% of the national colobus population. The Diani and Shimoni forests in particular, are highlighted as key habitat for future colobus (and coastal forest) conservation initiatives. Local semistructured interviews and archival research into the historical distribution of the taxon in North Coast Kenya confirmed its occurrence (and subsequent range contraction) in the Kilifi District, with the last sightings occurring in the Arabuko Sokoke Forest in 1979. Differences in the settlement distribution, associated habitat loss and hunting preferences of the nine coastal tribes (Mijikenda) may explain why colobus have disappeared from the north coast, but persist in the south. Am. J. Primatol. 69:664–680, 2007. © 2007 Wiley‐Liss, Inc.
Mutational changes in S‐cone opsin genes common to both nocturnal and cathemeralAotusmonkeys
Authors: Levenson David H. , Fernandez‐duque Eduardo , Evans Sian , Jacobs Gerald H. 
Published: January 2007

AbstractAotusis a platyrrhine primate that has been classically considered to be nocturnal. Earlier research revealed that this animal lacks a color vision capacity because, unlike all other platyrrhine monkeys,Aotushas a defect in the opsin gene that is required to produce short‐wavelength sensitive (S) cone photopigment. Consequently,Aotusretains only a single type of cone photopigment. Other mammals have since been found to show similar losses and it has often been speculated that such change is in some fashion tied to nocturnality. Although most species ofAotusare indeed nocturnal, recent observations show thatAotus azarai, an owl monkey species native to portions of Argentina and Paraguay, displays a cathemeral activity pattern being active during daylight hours as frequently as during nighttime hours. We have sequenced portions of the S‐cone opsin gene inA. azaraiandAotus nancymaae, the latter a typically nocturnal species. The S‐cone opsin genes in both species contain the same fatal defects earlier detected forAotus trivirgatus. On the basis of the phylogenetic relationships of these three species these results imply thatAotusmust have lost a capacity for color vision early in its history and they also suggest that the absence of color vision is not compulsively linked to a nocturnal lifestyle. Am. J. Primatol. 69:757–765, 2007. © 2007 Wiley‐Liss, Inc.
Mark Tests for mirror self‐recognition in capuchin monkeys (Cebus apella) trained to touch marks
Authors: Roma Peter G. , Silberberg Alan , Huntsberry Mary E. , Christensen Chesley J. , Ruggiero Angela M. , Suomi Stephen J. 
Published: January 2007

AbstractIn Experiment 1, three capuchin monkeys (Cebus apella) were exposed to a mirror in their home cage for 3 days and then given food treats for touching orange marks located on the surface of an experimental chamber. Following training, a mirror was added to the chamber to see if the monkeys would use it to guide non‐reinforced contacts with an orange mark on their foreheads that was only visible as a mirror reflection (mark test). Two monkeys touched the head‐mark more often with the mirror present than absent, but no mark touches were emitted while looking at the mirror. In Experiment 2, the monkeys were rewarded for touching orange marks on their bodies that were directly visible, followed by another head‐mark test. Again, two monkeys touched the mark more often with the mirror present than absent, but these contacts were not emitted while looking at the mirror. Since facing the mirror while mark touching was not required for reinforcement during training, Experiment 3 further tested the possibility that increased mark touching in the presence of the mirror during Experiments 1 and 2 was the result of a memorial process. For this, a final, novel mark test was conducted using an orange mark on the neck that was only visible as a reflection (Experiment 3). No monkeys passed this test. These are the first mark tests given to capuchin monkeys. The results are consistent with the finding that no monkey species is capable of spontaneous mirror self‐recognition. The implications of sequential training and mark testing for comparative evaluations of mirror self‐recognition capacity are discussed. Am. J. Primatol. 69:989–1000, 2007. © 2007 Wiley‐Liss, Inc.
Short‐term fasting leads to inhibition of responsiveness to LH‐stimulated testosterone secretion in the adult male bonnet monkey
Authors: Medhamurthy R. , Priyanka G. , Vinuthan M.K. , Manjunatha A.M. 
Published: January 2007

AbstractA variety of stressors including fasting profoundly inhibit reproductive function in mammals. Although the effect of short‐term fasting on gonadotropic axis is well established, the direct effects of fasting on gonads have not been reported. The objectives of the present experiments were to examine the effect of short‐term fasting on circulating luteinizing hormone (LH) and testosterone (T) secretion, and to determine the responsiveness of testis to exogenous recombinant human (rh) LH treatment in male bonnet monkeys. In addition, an experiment was carried out to examine whether brief inhibition of endogenous LH secretion causes alteration in testicular responsiveness. Adult male monkeys were fasted for 1 day for examining the circulating endocrine hormone concentrations and challenged with rhLH injection 1 day after fasting. Food withdrawal for 1 day resulted in significant (P<0.05) decrease in LH, T and increase in cortisol concentrations. Surprisingly, T secretion in response to direct stimulation of Leydig cells by LH was not observed in fasted monkeys. In fed monkeys, treatment with Antide (a specific gonadotropin releasing hormone receptor antagonist to inhibit pituitary LH secretion) for 1 day did not compromise T secretion stimulated by rhLH, suggesting that loss of responsiveness of testis to exogenous LH treatment in fasted monkeys was not because of interruption in pituitary LH stimulation of the testis. The results indicate that short‐term fasting in adult male monkeys cause inhibition of LH and T secretion, and inhibition of responsiveness of testis to LH stimulation. Am. J. Primatol. 69:791–801, 2007. © 2007 Wiley‐Liss, Inc.
N‐acetylcysteine reduces lipopolysaccharide‐sensitized hypoxic‐ischemic brain injury
Authors: Wang Xiaoyang , Svedin Pernilla , Nie Chunxia , Lapatto Risto , Zhu Changlian , Gustavsson Malin , Sandberg Mats , Karlsson Jan‐Olof , Romero Roberto , Hagberg Henrik , Mallard Carina 
Published: January 2007

AbstractObjectiveMaternal inflammation/infection alone or in combination with birth asphyxia increases the risk for perinatal brain injury. Free radicals are implicated as major mediators of inflammation and hypoxia‐ischemia (HI)–induced perinatal brain injury. This study evaluated the neuroprotective efficacy of a scavenging agent, N‐acetylcysteine (NAC), in a clinically relevant model.MethodsLipopolysaccharide (LPS)‐sensitized HI brain injury was induced in 8‐day‐old neonatal rats. NAC was administered in multiple doses, and brain injury was evaluated at 7 days after HI.ResultsNAC (200mg/kg) provided marked neuroprotection with up to 78% reduction of brain injury in the pre+post‐HI treatment group and 41% in the early (0 hour) post‐HI treatment group, which was much more pronounced protection than another free radical scavenger, melatonin. Protection by NAC was associated with the following factors: (1) reduced isoprostane activation and nitrotyrosine formation; (2) increased levels of the antioxidants glutathione, thioredoxin‐2, and (3) inhibition of caspase‐3, calpain, and caspase‐1 activation.InterpretationNAC provides substantial neuroprotection against brain injury in a model that combines infection/inflammation and HI. Protection by NAC was associated with improvement of the redox state and inhibition of apoptosis, suggesting that these events play critical roles in the development of lipopolysaccharide‐sensitized HI brain injury. Ann Neurol 2007
Acylation of iminochitosan: Its effect on blending with cellulose acetate
Authors: El‐Tahlawy Khaled , Abdelhaleem Essam , Hudson Samuel M. , Hebeish Ali 
Published: January 2007

AbstractChitosan has many similarities to cellulose, but there are few good direct solvents for codissolving them. Cellulose is cheaper than chitosan, and a blend film of the two would be expected to exhibit the desirable properties of both these polysaccharides. The formation of chitosanic and cellulosic acyl derivatives is an attractive route for the preparation of these fibers and films. They are soluble in common organic solvents, and in many cases it is not difficult to regenerate cellulose or chitosan from these derivatives. However, it may be desirable to protect the amino group from these reactions. Iminochitosan was used in the present study for that purpose. Chitosan at four molecular weights was prepared using an HCl/isopropanol binary system. The hydrolyzed chitosan was allowed to react with salicylaldehyde via Schiff base formation. Acylation of iminochitosan was carried out by its reaction with different acid halides containing a varied number of carbon atoms in the presence of a catalyst. The main factors that affected the dissolution of acylated iminochitosan in different organic solvents are described. Films from blends of n‐butyryl iminochitosan with cellulose acetate were prepared and are described. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 727–734, 2007
Synthesis and study of metal ion sorption capacity of xanthan gum‐g‐2‐acrylamido‐2‐methyl‐1‐propane sulphonic acid
Authors: Srivastava Abhishek , Behari Kunj 
Published: January 2007

AbstractIn this study, xanthan gum‐g‐2‐acrylamido‐2‐methyl‐1‐propane sulfonic acid (AMPS) was synthesized by free radical polymerization using bromate/thiourea redox pair in inert atmosphere. Various studies have been conducted to observe the effect of reactants on grafting parameters by varying the reactant concentration and to understand the physical–chemical properties. Grafting ratio, add on, and conversion showed a decrease on increasing the concentration of xanthan gum. The grafting parameters increased on increasing the concentration of AMPS from 3 × 10−2 to 6 × 10−2 mol dm−3, BrO3 from 2 × 10−3 to 8 × 10−3 mol dm−3, and thiourea from 1 × 10−3 to 2.8 × 10−3 mol dm−3, respectively. Optimum temperature and time for grafting of AMPS on xanthan gum were found to be 35°C and 120 min. Water swelling capacity, swelling ratio, metal ion uptake, and metal retention capacity were also studied, and it was found that grafted polymer shows better enhancement in these properties than substrate. Graft copolymer was characterized by FTIR and thermal analysis. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 470–478, 2007
Synthesis and nonlinear optical properties of polyphosphazenes with binaphtholyl and indole side groups
Authors: Li Zhen , Qin Jingui , Yang Zhou , Ye Cheng 
Published: January 2007

AbstractNew polyphosphazenes (P2 and P3) that contain indole‐based chromophore and binaphtholyl moieties as side chains are prepared by a new postfunctional strategy. Molecular structural characterization for the high polymers was presented by 1H‐NMR, IR and UV‐Visible spectra, gel permeation chromatograply, and differential scanning calorimetry. The glass transition temperature of P2 was determined to be 168°C, higher than those polyphosphazenes reported previously in the literatures. P2 and P3 are thermal stable and easily soluble in high polar solvents. The maximum absorption of P2 in chloroform was at 425 nm and cuts off at about 550 nm, while that of P3 was 393 nm and 500 nm, respectively, which resulted in a wide transparency window. The poled films of P2 and P3 reveal a resonant d33 value of 20 pm/V and 14 pm/V, respectively, by second harmonic generation measurements. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 365–371, 2007
Photophysical studies of polyvinylcarbazole polymer films
Authors: Patel Shruti , Ramrakhiani M. , Bisen D. P. 
Published: January 2007

AbstractPolyvinylcarbazole (PVK) films have been prepared by solution method. Their absorption spectra, photoluminescence, and electroluminescence have been studied. Absorption in pure PVK is found to be high at lower wavelengths in UV region and decreases in visible range. In case of I2 doped PVK, absorption is observed in visible region also. The photoluminescence is obtained in pure PVK when exited by violet or blue light but in case of I2 doped PVK, similar excitation gives low intensity peaks in yellow–green region. The results indicate that I2 levels in PVK causes absorption in 400–600 nm wavelength range and makes the deexcitation of the molecules nonradiative. Light emission by application of ac voltage from mains up to 100 V has been studied. Nonlinear increase in emission intensity has been observed with increasing voltage. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 722–726, 2007
Ozonolysis of polybutadienes with different microstructure in solution
Authors: Anachkov M. P. , Rakovsky S. K. , Zaikov G. E. 
Published: January 2007

AbstractThe reaction of ozone with 1,4‐cis‐polybutadiene and polybutadiene having the following linking of the butadiene units: 1,4‐cis (47%), 1,4‐trans (42%), 1,2 (11%) was investigated in CCl4 solution. It was found out by means of IR‐spectroscopy and 1H‐NMR spectroscopy that the basic ozonolysis products of both elastomers are ozonides and aldehydes. The aldehyde:ozonide ratio was 11 : 89 and 27 : 73 for E‐BR and BR, respectively. In addition, epoxide groups were detected, only in the case of BR, and their yield was about 10% of that of the aldehydes. On the basis of BR ozonolysis it was established that the ozonide yield from 1,4‐trans units is about 50%. By using the aldehyde yields, an evaluation was made of the efficiency of ozone degradation of the two polybutadienes, according to which the respective value of BR is considerably higher than that of E‐BR. A reaction mechanism is proposed, which explains the formation of the identified functional groups and the differences in the ozone degradation of the studied elastomers. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 427–433, 2007
Thermal degradation of epoxy resin reinforced with polypropylene fibers
Authors: Prabhu T. Niranjana , Hemalatha Y. J. , Harish V. , Prashantha K. , Iyengar P. 
Published: January 2007

AbstractThe influence of polypropylene fibers on the thermal degradation of epoxy composites was investigated with thermogravimetric analysis. Three composites with 5, 10, or 15 wt % polypropylene fibers were prepared with epoxy as a matrix material. The polypropylene fibers, used as reinforcing materials, retarded the thermal decomposition, and increasing the weight percentage of the fiber material increased the thermal stability to a certain extent. Of the three composites, the 10 wt % polypropylene fiber/epoxy resin composite showed very good thermal stability, which was indicated by the increase in the resin decomposition temperature from 280°C for the 5 wt % polypropylene fiber/epoxy resin composite to 375°C for the 10 wt % polypropylene fiber/epoxy resin composite. The Horowitz–Metzger method was used to calculate the activation energies, and the results were tabulated. A morphological analysis was carried out with scanning electron microscopy to evaluate the dispersion of the fibers in the epoxy matrix. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 500–503, 2007
Synthesis of starch‐based plastic films by electron beam irradiation
Authors: El‐Mohdy H. L. Abd 
Published: January 2007

AbstractStarch‐based plastic films were prepared by the electron beam irradiation of starch and poly(vinyl alcohol) (PVA) in a physical gel state at room temperature. The influence of starch/PVA composition, irradiation dose, and plasticizer (glycerol) on the properties of the plastic films was investigated. The gel fraction of the starch/PVA films increased with both the radiation dose and PVA content in the plastic film and decreased with increasing glycerol concentration. The starch/PVA compatibility was determined by measurement of the thermal properties of the starch/PVA blends with various compositions with differential scanning calorimetry. The swelling of the starch/PVA films increased with increasing PVA content and decreasing irradiation dose. Mechanical studies were carried out, and the tensile strength of the films decreased at high starch ratios in the starch‐based mixture. This was due to the decrease in the degree of crosslinking of starch. Furthermore, when PVA, a biodegradable and flexible‐chain polymer, was incorporated into the starch‐based films, the properties of the films, such as the flexibility (elongation at break), were obviously improved. The tensile strength of the films decreased with increasing glycerol concentration, but elongation at break increased up to a maximum value at a 20% glycerol concentration, and then, it leveled off and decreased slightly. Biodegradation of the starch/PVA plastic films was indicated by weight loss (%) after burial in soil and morphological shape, which was detected by scanning electron microscopy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 504–513, 2007
Influence of support friability and concentration of α‐olefins on gas‐phase ethylene polymerization over polymer‐supported metallocene/methylaluminoxane catalysts
Authors: Hammawa Hassan , Wanke Sieghard E. 
Published: January 2007

AbstractThe effects of support friability (Φ) and ethylene/comonomer ratios were investigated over supported metallocene/methylaluminoxane catalysts prepared with nine different porous polymeric supports and various comonomer concentrations with a 2‐L reactor operated in the semibatch gas‐phase mode at 80°C and 1.4 MPa. Φ of the supports was measured with a newly devised method. The performance of the supported catalysts depended on support Φ as follows. The average homopolymerization activities varied from less than 6 t of polyethylene (PE) (mol of Zr)−1 h−1 for low‐Φ catalysts to 10–20 t of PE (mol of Zr)−1 h−1 for moderate‐Φ catalysts and up to 100 t of PE (mol of Zr)−1 h−1 for the high‐Φ catalysts. The presence of 1‐hexene and propylene comonomers increased the activity of the low‐Φ catalysts by up to 20‐fold and 50‐fold, respectively; that is, there were very marked comonomer effects. Activity enhancement by 1‐hexene was less than 3‐fold for the moderate‐Φ catalysts, whereas the high‐Φ catalysts showed little activity enhancement. Sometimes, 1‐hexene even resulted in activity reductions. Very different particle morphologies were obtained with the catalysts of different Φ's. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 514–527, 2007
X‐ray pole figures to assess orientation in PVC sheets
Authors: Gilbert Marianne , Ross David H , Kim Hwan Chul 
Published: January 2007

AbstractA series of X‐ray pole figures were obtained from oriented and unoriented rigid polyvinyl chloride sheets. From these, information about crystallite orientation in uniaxially and biaxially drawn sheets stretched at 90°C was obtained. Uniaxial orientation produced two crystallite orientations with the extent of orientation increasing with draw ratio; for biaxial samples the chain direction (c) was distributed uniformly in the plane of the sheet, with the planar orientation improving as draw ratio increased. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 528–535, 2007
Spectroscopic study of interactions between model direct dyes and cotton
Authors: Pielesz Anna 
Published: January 2007

AbstractAlthough examined for years, interactions between direct dyes and the chemical structure of cotton cellulose remain an interesting, and still not entirely known, chemical phenomenon occurring in the fiber. Ten model azo dyes have been studied in aqueous solution, as dye powders and on cotton fabric using 13C MAS NMR and UV–visible spectroscopy. NMR spectroscopy indicates that model azo dyes, especially dye 8, interact by π‐stacking at the central biphenyl group, and that there is hydrogen bonding with cellulose. Model azo dyes are present as the azo or hydrazone tautomer. The UV–visible λmax indicate that shifts are attributed to adsorption of model azo dyes into cellulose surfaces. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 758–766, 2007
Synthesis and characterization of novel saponified guar‐graft‐poly(acrylonitrile)/silica nanocomposite materials
Authors: Singh Vandana , Tiwari Ashutosh , Pandey Sadanand , Singh Somit K. , Sanghi Rashmi 
Published: January 2007

AbstractThe combination of carbohydrates with silicon‐based ceramic materials offers attractive means of production for high performance materials. Present article describes the synthesis of novel nanocomposites out of SiO2 and saponified guar‐graft‐poly(acrylonitrile) (SG). Tetraethoxysilane was used as the precursor for silica and growth of SiO2 phase was allowed concurrently in the presence of SG. The material so obtained was thermally treated at 80°C, 160°C, 500°C, and 900°C to study the effect of thermal curing on its properties. During the curing process, silanol surface groups of silica globules reacted to create the reinforced SiO2‐SG substance. It was observed that at 900°C, the SiO2 phase crystallized out in tetragonal shape (similar to Cristobalite form of silica) in presence of SG. The chemical, structural and textural characteristics of the composites were determined by FTIR, XRD, TGA‐DTA, SEM and BET studies. The materials were also evaluated as efficient Zn2+ metal binder. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 536–544, 2007
Effect of solid‐state shearing of poly(ethylene terephtalate) on isothermal crystallization and fiber structure formation
Authors: Huang Liqian , Pan Lihua , Inoue Takashi 
Published: January 2007

AbstractSolid‐state shearing was applied on recycled poly(ethylene terephtalate) (PET) using twin‐screw extruder. The shearing effect on isothermal crystallization was investigated by DSC. Structure formation in melt spinning was also studied by characterizing the spun fibers. It was found that the solid‐state shearing imposes a great influence on its crystallization behavior. Crystallization peak temperature of the sheared PET (199°C) was much higher than that of the PET without shearing (188°C). Overall isothermal crystallization rate was found to be accelerated to more than 50 times by the shearing. The shearing effect remained even after fiber spinning (melt processing). Differences in crystallization behavior, fiber structure formation, and tensile properties of the fibers were found. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 787–791, 2007