bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential effects of testosterone and 17β-estradiol on gonadal development in five anuran species
Authors: Piprek Rafał P , Pecio Anna , Kubiak Jacek Z , Szymura Jacek M
Published: May 2012

Sex hormones are essential for sexual differentiation and play a key role in the development of gonads in amphibians. The goal of this study was to evaluate the influence of exogenous sex steroids, testosterone, and 17β-estradiol (E2) on development of gonads in five anuran species differing in their evolutionary positions, sex determination, and mode of gonadogenesis. We found that in two closely related species of fire-bellied toad, Bombina bombina and Bombina variegata, testosterone and E2 exposure results in sex reversal as well as intersex and undifferentiated gonads. Similarly, sex reversal was observed in Hyla arborea after exposure to male or female sex steroids. Xenopus laevis was sensitive to E2 but only moderately to testosterone. In Bufo viridis, treatment with either sex hormone provoked a developmental delay in gonads and Bidder's organs. Therefore, susceptibility to hormonal sex reversal appeared species dependent but unrelated to genetic sex determination and the type of gonadogenesis. We also found that the onset of sex steroid exposure influences gonad differentiation and the meiotic status of the germ cells depends on their location within the gonad. Our findings reveal differential sensitivity of amphibians to testosterone and E2, establishing a hierarchy of sensitivity to these hormones among different anuran species.
Effects of Individual and Work‐related Factors on Incidence of Shoulder Pain in a Large Working Population
Authors: Bodin Julie , Ha Catherine , SéRazin Céline , Descatha Alexis , Leclerc Annette , Goldberg Marcel , Roquelaure Yves
Published: May 2012

Effects of Individual and Work‐related Factors on Incidence of Shoulder Pain in a Large Working Population: Julie BODIN,et al. LUNAM Université, Université d’Angers, Laboratoire d’ergonomie et d’épidémiologie en santé au travail (LEEST), France—

Objectives

The aim of this study was to assess the effects of individual and work‐related factors on the incidence of shoulder pain in a large French working population.

Methods

A total of 3,710 workers of a French region were randomly included in a cross‐sectional study between 2002 and 2005. They completed a self‐administered questionnaire about musculoskeletal symptoms, individual factors and exposure to work constraints. In 2007, 2,332 responded to a follow‐up questionnaire. The Nordic questionnaire was used both times to assess shoulder pain during the preceding 7 days. Associations between incident shoulder pain and individual and work‐related factors at baseline were studied by multivariate logistic regression for both genders.

Results

A total of 946 men and 709 women without shoulder pain at baseline were eligible for the analyses. At follow‐up, 105 men (11.1%) and 145 women (20.5%) reported shoulder pain. For men, age (OR 3.3, 95% CI, 1.7–6.5 for ≥50 yr), working with arms above the shoulder (1.5; 1.0–2.3) and high perceived physical exertion (1.6; 1.0–2.5) increased the risk of incident shoulder pain. For women, the factors associated with incident shoulder pain were age (2.9; 1.5–5.8 for ≥50 yr), obesity (2.5; 1.4–4.5), temporary employment (2.1; 1.1–3.7), high perceived physical exertion (2.2; 1.4–3.5) and low decision latitude (1.6; 1.0–2.3).

Conclusion

Age was the strongest predictor of incident shoulder pain in both genders. BMI and biomechanical and psychosocial factors were also identified as risk factors, whereas no factor related to work organization remained in the final models.
Neonatal Apneic Seizure of Occipital Lobe Origin: Continuous Video-EEG Recording
Authors: Castro Conde José Ramón , González-Hernández Tomás , González Barrios Desiré , González Campo Candelaria
Published: May 2012

We present 2 term newborn infants with apneic seizure originating in the occipital lobe that was diagnosed by video-EEG. One infant had ischemic infarction in the distribution of the posterior cerebral artery, extending to the cingulate gyrus. In the other infant, only transient occipital hyperechogenicity was observed by using neurosonography. In both cases, although the critical EEG discharge was observed at the occipital level, the infants presented no clinical manifestations. In patient 1, the discharge extended to the temporal lobe first, with subtle motor manifestations and tachycardia, then synchronously to both hemispheres (with bradypnea/hypopnea), and the background EEG activity became suppressed, at which point the infant experienced apnea. In patient 2, background EEG activity became suppressed right at the end of the focal discharge, coinciding with the appearance of apnea. In neither case did the clinical description by observers coincide with video-EEG findings. The existence of connections between the posterior limbic cortex and the temporal lobe and midbrain respiratory centers may explain the clinical symptoms recorded in these 2 cases. The novel features reported here include video-EEG capture of apneic seizure, ischemic lesion in the territory of the posterior cerebral artery as the cause of apneic seizure, and the appearance of apnea when the epileptiform ictal discharge extended to other cerebral areas or when EEG activity became suppressed. To date, none of these clinical findings have been previously reported. We believe this pathology may in fact be fairly common, but that video-EEG monitoring is essential for diagnosis.
The Distribution of Physical Activity in an After-school Friendship Network
Authors: Gesell Sabina B. , Tesdahl Eric , Ruchman Eileen
Published: May 2012

OBJECTIVE:

To examine whether a child’s friendship network in an afterschool program influences his/her physical activity.

METHODS:

Three waves of data were collected from school-aged children participating in aftercare (n = 81; mean [SD] age, 7.96 [1.74] years; 40% African American, 39% white, and 19% Latino) a name generator survey was used to map each child’s social network, and accelerometers were used to measure physical activity. We applied stochastic actor-based modeling for social networks and behavior.

RESULTS:

Children did not form or dissolve friendships based on physical activity levels, but existing friendships heavily influenced children’s level of physical activity. The strongest influence on the amount of time children spent in moderate-to-vigorous activity in the afterschool hours was the activity level of their immediate friends. Children consistently made adjustments to their activity levels of 10% or more to emulate the activity levels of their peers (odds ratio [OR] = 6.89, P < .01). Age (OR = 0.92, P < .10) and obesity status (OR = 0.66, P < .10) had marginally significant and relatively small direct effects on the activity. Gender had no direct effect on activity.

CONCLUSIONS:

These results suggest that friendship ties play a critical role in setting physical activity patterns in children as young as 5 to 12 years. Children’s activity levels can be increased, decreased, or stabilized depending on the activity level of their immediate social network during a 12-week afterschool program. Network-based interventions hold the potential to produce clinically significant changes to children’s physical activity.
Inhibition of Claudin‐11 and Occludin Expression in Rat Sertoli Cells by Mono‐(2‐Ethylhexyl) Phthalate Through p44/42 Mitogen‐Activated Protein Kinase Pathway
Authors: Chiba Koji , Kondo Yutaka , Yamaguchi Kohei , Miyake Hideaki , Fujisawa Masato
Published: May 2012

ABSTRACT: Our objectives were to evaluate the effects of mono(2‐ethylhexyl) phthalate (MEHP) on tight junctions (TJ) in cultured rat Sertoli cells (SC) and to investigate changes in the signal transduction pathways in SCs following MEHP treatment. SCs were isolated and purified from the testes of 18‐day‐old Sprague Dawley rats and incubated at 34°C for 3 days. After treatment of SCs with either the vehicle or MEHP for 0.5, 1, 3, 6 and 24 hours, whole cell lysates were isolated from each replicate to prepare RNA and protein. Expression levels of claudin‐11, occludin, and zonula occludens‐1 (ZO‐1) mRNA were evaluated by quantitative real‐time reverse transcription–polymerase chain reaction and changes in signal transduction pathways possibly induced by MEHP treatment were assessed by Western blot analyses. MEHP treatment led to significant decreases in the expression of claudin‐11 and occludin mRNA, but not that of ZO‐1, in rat SCs. Exposure of rat SCs to MEHP resulted in the marked induction of phosphorylated p44/42 mitogen‐activated protein kinase (MAPK), whereas other pathways examined in this study were not activated by MEHP. Furthermore, treatment of rat SCs with a specific inhibitor of p44/42 MAPK prevented the MEHP‐induced down‐regulation of claudin‐11 and occludin. These findings demonstrate that MEHP exposure inhibited the expression of claudin‐11 and occludin mRNA in rat SCs through the p44/42 MAPK pathway, suggesting the possible involvement of MEHP in spermatogenic function by regulating major components of TJs in SCs.
Induction and Persistence of Abnormal Testicular Germ Cells Following Gestational Exposure to Di‐(n‐Butyl) Phthalate in p53‐Null Mice
Authors: Saffarini Camelia M. , Heger Nicholas E. , Yamasaki Hideki , Liu Tao , Hall Susan J. , Boekelheide Kim
Published: May 2012

ABSTRACT: Phthalate esters are commonly used plasticizers found in many household items, personal care products, and medical devices. Animal studies have shown that in utero exposure to di‐(n‐butyl) phthalate (DBP) within a critical window during gestation causes male reproductive tract abnormalities resembling testicular dysgenesis syndrome. Our studies utilized p53‐deficient mice for their ability to display greater resistance to apoptosis during development. This model was chosen to determine whether multinucleated germ cells (MNG) induced by gestational DBP exposure could survive postnatally and evolve into testicular germ cell cancer. Pregnant dams were exposed to DBP (500 mg/kg/day) by oral gavage from gestational day 12 until birth. Perinatal effects were assessed on gestational day 19 and postnatal days 1, 4, 7, and 10 for the number of MNGs present in control and DBP‐treated p53‐heterozygous and null animals. As expected, DBP exposure induced MNGs, with greater numbers found in p53‐null mice. Additionally, there was a time‐dependent decrease in the incidence of MNGs during the early postnatal period. Histologic examination of adult mice exposed in utero to DBP revealed persistence of abnormal germ cells only in DBP‐treated p53‐null mice, not in p53‐heterozygous or wild‐type mice. Immunohistochemical staining of perinatal MNGs and adult abnormal germ cells was negative for both octamer‐binding protein 3/4 and placental alkaline phosphatase. This unique model identified a role for p53 in the perinatal apoptosis of DBP‐induced MNGs and provided insight into the long‐term effects of gestational DBP exposure within a p53‐null environment.
Vitrification of Human ICSI/IVF Spermatozoa Without Cryoprotectants: New Capillary Technology
Authors: Isachenko V. , Maettner R. , Petrunkina A. M. , Sterzik K. , Mallmann P. , Rahimi G. , Sanchez R. , Risopatron J. , Damjanoski I. , Isachenko E.
Published: May 2012

ABSTRACT: The aim of this study was to develop and to test the standardized aseptic technology of permeable cryoprotectant‐free vitrification of human spermatozoa in capillaries (for intracytoplasmic sperm injection [ICSI] or in vitro fertilization [IVF]). To test the effect of vitrification on basic sperm parameters, each of 68 swim‐up–prepared ejaculates from oligo‐astheno‐terato‐zoospermic patients were aliquoted and distributed into 3 groups: 1) nontreated control, 2) 10 μL of spermatozoa cryopreserved by slow conventional freezing with glycerol‐contented medium, and 3) 10 μL of spermatozoa vitrified in 50‐μL plastic capillaries in culture medium with 0.25 M sucrose. Spermatozoa motility (1, 24, and 48 hours after warming), plasma membrane integrity, acrosomal integrity, and spontaneous capacitation‐like changes were determined after warming. Aseptic cryoprotectant‐free vitrification showed a significantly stronger cryoprotective effect compared with conventional freezing. One hour after warming, motility, plasma membrane integrity, and acrosomal integrity were significantly higher than is observed for conventionally frozen spermatozoa (28% vs 18%, 56% vs 22%, and 55% vs 21%, respectively; P < .05), although lower than in fresh spermatozoa (35%, 96%, and 84%, respectively; P < .05). Capacitation‐like changes did not differ significantly between vitrified and conventionally frozen samples (8% vs 9%, respectively; P > .1) (2% in fresh spermatozoa). The newly developed technology of aseptic vitrification of human spermatozoa in capillaries can effectively preserve these cells from cryo‐injures. Spermatozoa, vitrified by this technology, are free from seminal plasma owing to swim‐up preceding vitrification and are free from permeable cryoprotectants. They are ready for further use immediately after warming without any additional treatment. Therefore, the reported technology has a great potential for use in ICSI/IVF.
Immunohistochemical evidence for the presence of a vasoactive intestinal peptide, neuropeptide Y and substance P in rat adrenal medulla after heat stress
Authors: Petrovic-Kosanovic Dragana , Koko Vesna
Published: May 2012

Immunohistochemistry revealed the presence of VIP-, NPY- and
SP-immunoreactivity in the rat adrenal medulla. VIP- and NPY-immunoreactivity
was detected in chromaffin and ganglion cells and in nerve fibers, but
SP-immunoreactivity was found only in chromaffin cells. After acute heat
stress, VIP- and NPY- immunoreactivities in cells and nerve fibers were
reduced, probably as a result of the release of these peptides with
catecholamines. The absence of SP-immunoreactive ganglion cells in the
adrenal medulla suggests that the SP-immunoreactive nerve fibers are
extrinsic in origin.
Enhancement of antimicrobial activity of antibiotics and antifungals by the use of natural products from Pityrogramma calomelanos (L.) link
Authors: Souza Teógenes , Morais-Braga Maria , Costa José , Saraiva Antônio , Coutinho Henrique
Published: May 2012

The ethanol extract and methanol fraction of Pityrogramma calomelanos (L.)
link were evaluated for antibacterial, antifungal and modulatory activities
against strains of Escherichia coli, Pseudomonas aeruginosa, Staphylococcus
aureus, Candida albicans, C. krusei and C. tropicalis. The antimicrobial
activity of the natural products was evaluated by the microdilution method
associated or not with aminoglycosides and antifungals. The ethanol extract
and methanol fraction of P. calomelanos showed good activity against S.
aureus when associated with aminoglycosides and with benzoilmetronidazol
against species of the genus Candida. These results indicate that P.
calomelanos should be studied as a possible source of natural products to
combat bacteria and fungi either directly or by modulating the mechanisms of
resistance of these microorganisms, enhancing the antimicrobial activity of
these drugs and combating microbial resistance.
Expression of small heat shock proteins and heat tolerance in potato (Solanum tuberosum L.)
Authors: Savic Jelena , Dragicevic Ivana , Pantelic D. , Oljaca Jasmina , Momcilovic Ivana
Published: May 2012

We have examined the correlation between heat tolerance and small heat shock
protein (sHSP) expression under heat stress conditions in potato (Solanum
tuberosum L.). The relative heat tolerance of nine potato cultivars grown
under greenhouse conditions was determined using the electrolyte leakage
assay (ELA), a standard quantitative assay for heat tolerance. Three
cultivars differing in heat tolerance were selected and designated as
heat-tolerant (?Laura?), moderately sensitive (?Liseta?) and heat-sensitive
(?Agria?) genotypes. The expression of cytosolic HSP18 and chloroplast HSP21
was analyzed at the protein level in the leaves of selected cultivars, both
ex vitro- and in vitro-grown, after heat stress or control treatment.
Immunoblot analysis revealed heat-induced HSP18 and HSP21 expression in all
examined genotypes. A similar pattern of examined sHSP expression was
observed ex vitro and in vitro: heat-tolerant ?Laura? accumulated higher
levels of both HSP18 and HSP21 compared to heat-sensitive ?Liseta? and
?Agria?. Our results indicate that ELA combined with immunoblot analysis of
sHSP accumulation under HS conditions, might be considered as a reliable
procedure in screening potato genotypes for heat tolerance. To our knowledge,
this is the first study where sHSP expression between ex vitro- and in
vitro-grown potato plants was compared.
North Atlantic Oscillation (NAO) and insect damage in Serbian forests
Authors: Ducic V. , Lukovic Jelena , Milenkovic M. , Curcic Nina
Published: May 2012

This paper examines the relationship between North Atlantic Oscillation (NAO)
and damage made by insects in Serbian forests. The damage has been separated
into three groups: bark beetles, gypsy moth and damage made by other insects.
For North Atlantic Oscillation the NAO index is used. The period of
investigation was 1969-2001. Data were studied on an annual scale as well as
with five-year moving averages. Analysis showed a statistically significant
correlation for NAO index and gypsy moth.
Enhancement of the reproductive potential of Mallada boninensis Okamoto (Neuroptera: Chrysopidae), a predator of red spider mite infesting tea: An evaluation of artificial diets
Authors: Vasanthakumar Duraikkannu , Roobakkumar Amsalingam , Rahman Jasin , Kumar Pandian , Sundaravadivelan Chandran , Babu Azariah
Published: May 2012

Green lacewing Mallada boninensis is an important predator of various
soft-bodied arthropods, including red spider mites in tea. Efforts were made
to develop mass rearing technology for this predator in a cost effective
manner. Three combinations of artificial diets (Protinex (AD1), egg yolk
(AD2) and royal jelly (AD3) based) were evaluated in comparison with standard
diet (Protinex + Honey). All the tested diets influenced the egg-laying
capacity of M. boninensis. The egg yolk-based diet resulted in more egg
production than the other two diets. Survival of all life stages of M.
boninensis was also observed on each diet and no significant difference was
noticed. Results revealed that the egg yolk-based diet is the best of the
three diet combinations tested in view of high fecundity and survival rate of
M. boninensis.
Flea beetles (Coleoptera: Chrysomelidae: Alticinae) collected by malaise trap method in Gölcük Natural Park (Isparta, Turkey), with a new record for Turkish fauna
Authors: Aslan Gül , Japoshvili G. , Aslan B. , Karaca I.
Published: May 2012

This study is based on Alticinae (Coleoptera: Chrysomelidae) material
collected by Malaise trapping which is different from other standardized
collecting methods. A total of 19 flea beetle species belonging to 6 genera
were collected from G?lc?k Natural Park, Isparta (Turkey) during 2009. The
species are listed in a table together with distributional data in Turkey.
Among them, Longitarsus curtus (Allard, 1860) is recorded for the first time
in Turkey. L. monticola Kutschera, 1863 and L. curtus are recently separated
synonyms and thus all data referring to the distribution of both species are
currently important. Hence, the zoogeographical distribution of the new
record is reviewed with some remarks; habitus and genitalia are illustrated.
The effect of the polar solvents on the synthesis of poly(urethane-urea-siloxane)s
Authors: Balaban Milica , Antic Vesna , Pergal Marija , Francolini Iolanda , Martinelli Andrea , Djonlagic Jasna
Published: May 2012

Segmented poly(urethane-urea-siloxanes) (PUUS) based on 4,4?- methylene
diphenyl diisocyanate-ethylene diamine (MDI-ED) hard segments and
hidroxypropyl-terminated poly(dimethylsiloxane) (PDMS, M n =1000 g mol-1)
soft segments were prepared under various experimental conditions. The
copolymers with constant molar ratio of hard and soft segments (PDMS:MDI:ED =
1:2:1; 20 wt. % of the hard segments) were synthesized in two different
solvent mixtures, by two-step polyaddition procedure. The first one was
THF/DMAc with different co-solvent ratio (1/1, 1/2 and 1/9, v/v), whereas the
second one was THF/NMP (1/9, v/v). The reaction conditions were optimized by
varying the co-solvents ratio, the concentration of the catalyst, the initial
monomer concentration, as well as the time of the first and the second step
of reaction. The effect of the experimental conditions on the size of PUUS
was investigated by gel permeation chromatography (GPC) and viscometry of the
dilute solutions [?]. The copolymers with the highest molecular weights were
obtained in the THF/NMP mixture (1/9, v/v). The structure and composition of
the copolymers were determined by 1H NMR and FTIR spectroscopy. The
morphology of the synthesized copolymers was investigated by atomic force
microscopy (AFM), while the thermal properties were studied by differential
scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The surface
properties were evaluated by measuring the water contact angle (WCA). The
copolymers showed phase separated microstructure and were stable up to 200?C
in nitrogen.
UV-induced change in quercetin antioxidant activity toward benzophenone initiated lipid peroxidation
Authors: Zvezdanovic Jelena , Markovic Dejan , Cvetkovic Dragan , Stanojevic Jelena
Published: May 2012

The aim of this work is to estimate the degradation and change in antioxidant
activity of quercetin in the presence of two different mixtures of
phospholipids in methanol solution, under continuous UV-irradiation from
three different sub-ranges (UV-A, UV-B and UV-C), in the presence and in the
absence of selected UV-absorbing photosensitizer, benzophenone. Quercetin is
employed to control lipid peroxidation process generated by UV-irradiation,
by absorbing part of the UV-incident light, or/and by scavenging the
involved, created free radicals. The results show that quercetin undergoes to
irreversible destruction, highly dependent on UV-photons energy input, more
expressed in the presence than in the absence of benzophenone. In the same
time quercetin expresses suppression effect on lipid peroxidation processes
in UV-irradiated phospholipid mixtures in both cases - absence or presence of
benzophenone (more or less effective, respectively). In UV-C-irradiated
mixtures, benzophenone photosensitizing function is significantly reduced due
to its strong absorption in the same UV-C spectral range, therefore affecting
less antioxidant activity of the remained quercetin.
SHP-2 and PTP-pest induction during Rb-E2F associated apoptosis
Authors: Morales Liza , Pena Karina , Kim Dae , Lieman Jonathan
Published: May 2012

Apoptosis is intimately connected to cell cycle regulation via the Retinoblastoma (Rb)-E2F pathway and thereby serves an essential role in tumor suppression by eliminating aberrant hyperproliferative cells. Upon loss of Rb activity, an apoptotic response can be elicited through both p53-dependent and p53-independent mechanisms. While much of this apoptotic response has been attributed to the p19ARF/p53 pathway, increasing evidence has supported the role of protein tyrosine phosphatases (PTPs) in contributing to the initiation of the Rb-E2F-associated apoptotic response. One protein tyrosine phosphatase, PTP-1B, which is induced by the Rb-E2F pathway, has been shown to contribute to a p53-independent apoptotic pathway by inactivating focal adhesion kinase. This report identifies two additional PTPs, SHP-2 and PTP-PEST, that are also directly activated by the Rb-E2F pathway and which can contribute to signal transduction during p53-independent apoptosis.
Behavior of various Nigerian quartz samples to repeated irradiation and heating
Authors: Oniya Ebenezer , Polymeris George , Tsirliganis Nestor , Kitis George
Published: May 2012

In the present work the sensitization of the entire glow-curve is studied in 6 different quartz samples of Nigerian origin. The investigation was applied to the un-fired “as is” samples as well as to samples fired at 900°C for 1 hour following cooling to room temperature. The results showed that in the case of “as is” glow-curve is sensitized as a whole. There is an abrupt transition from the “natural” sensitivity without any previous heating and the artificial sensitivity induced after the first heating. The sensitization is growing up strongly to the 10th heating but to a lower rate. The sensitization factor of the TL glow-peak at “110°C” was found to be linearly correlated to the higher temperature TL peaks. In the case of annealed samples there is an initial increase between the sensitivity immediately after the end of annealing and after the first heating. As the number of heating is increased up to the 10th heating the sensitization is stabilized at a constant value. The results are discussed in the frame-work of existing models and implications of the sensitization effect in various applications, while some explanations are attempted.
Life at the interface of two distinct landscapes-relationship of humans and environment in the periphery of the Danube-Tisza Interfluve between Hajós and Császártöltés
Authors: Knipl István , Sümegi Pál
Published: May 2012

Recent archeological and geoarcheological investigations have corroborated the notion of close interaction between man and environment in our study area during historical times. The riparian Sárköz, forming an interface between two major geographical regions of Transdanubia and the Great Hungarian Plains, has been continuously inhabited for the past 8000 years. Settlements were generally confined to areas above 90.5–91m ASL, with the exception of a few drier periods. This elevation can therefore be regarded as the margin of human settlement. The lower-lying areas correspond to the actual floodplain inundated for the major part of the year from which lag-surfaces stand out as island-like natural highs hosting the settlements themselves. The endowments and settlement pattern persisted from the Neolithic onwards until the terminal Modern Age, when measures aimed to ordain the area substantially altered the natural landscape.
Mullite and mullite-type crystal structures
Authors: Fischer Reinhard X. , Gaede-Köhler Andrea , Birkenstock Johannes , Schneider Hartmut
Published: May 2012

Synthetic mullites (Al4+2

x
Si2
–2

x
O10
–

x
) belong to one of the most important groups of ceramic materials. Their crystal structure consists of chains of edge-sharing AlO6 octahedra interconnected by tetrahedral double chains of TO4 (T = Al, Si) tetrahedra. The occurrence of oxygen vacancies is associated with the formation of triclusters of TO4 groups. The distribution of oxygen vacancies and the distribution of Al and Si on the tetrahedral sites are partially ordered yielding an incommensurately modulated crystal structure with satellite reflections in diffraction patterns. The number of symmetrically independent distribution patterns of oxygen vacancies is given for a 2 × 2 × 2 and a 3 × 3 × 2 superstructure model. Many other compounds have chain structures similar to mullite. These compounds are assigned to subgroups, all derived from a hypothetical tetragonal aristotype structure.
Metakaolin–nanosilver as biocide mullite precursor
Authors: Cabal Belén , Sanz Jesús , Díaz Luis A. , Torrecillas Ramón , Moya José S.
Published: May 2012

Incorporation of silver nanoparticles enhances the biocide functionality of Ag supported kaolinite/metakaolite materials. In this regard, structural evolution of supports in the presence of silver nanoparticles is investigated. For this purpose, 27Al and 29Si magic-angle-spinning nuclear magnetic resonance spectroscopy was applied to investigate the bonding between silver nanoparticles and kaolinite/metakaolin materials. The incorporation of silver nanoparticles, following a chemical or thermal reduction, does not change the structure of kaolin, whereas in the case of metakaolin, a preferential interaction with tetrahedral sheets was observed and some stabilization of hexacoordinated aluminium is favoured.
Crystal chemistry and properties of mullite-type Bi2
M
4O9: An overview
Authors: Schneider Hartmut , Fischer Reinhard X. , Gesing Thorsten M. , Schreuer Jürgen , Mühlberg Manfred
Published: May 2012

Bi2
M
4O9 (M = Al3+, Ga3+, Fe3+) belongs to the family of mullite-type crystal structures. The phases are orthorhombic with the space group Pbam. The backbones of the isostructural phases are edge-connected, mullite-type octahedral chains. The octahedral chains are linked by dimers of M
2O7 tetrahedral groups and by BiO polyhedra. The Bi3+ cations in Bi2
M
4O9 contain stereo-chemically active 6s2 lone electron pairs (LEPs) which are essential for the stabilization of the structure. Although the octahedral chains of the closely related Bi2Mn4O10 are similar to those of Bi2
M
4O9, Bi2Mn4O10 contains dimers of edge-connected, five-fold coordinated pyramids instead of four-fold coordinated tetrahedra. Also the 6s2 LEPs of Bi3+ in Bi2Mn4O10 are not stereo-chemically active. Complete and continuous solid solutions exist for Bi2(Al1
–

x
Fe
x
)4O9 and Bi2(Ga1
–

x
Fe
x
)4O9 (x = 0–1). Things are more complex in the case of the Bi2(Fe1
–

x
Mn
x
)4O9+

y
mixed crystals, where a miscibility gap occurs between x = 0.25–0.75. In the Fe-rich mixed crystals most Mn atoms enter the octahedra as Mn4+, with part of the tetrahedral dimers being replaced by fivefold coordinated polyhedra, whereas in the Mn-rich compound Fe3+ favorably replaces Mn3+ in the pyramids.

The crystal structure of Bi2
M
4O9 directly controls its mechanical properties. The stiffnesses of phases are highest parallel to the strongly bonded octahedral chains running parallel to the crystallographic
c
-axis. Perpendicular to the octahedral chains little anisotropy is observed. The temperature-induced expansion perpendicular to the octahedral chains is probably superimposed by contractions. As a result the
c
-axis expansion appears as relatively high and does not display its lowest value parallel to
c
, as could be inferred.

Maximally 6% of Bi3+ is substituted by Sr2+ in Bi2Al4O9 corresponding to a composition of (Bi0.94Sr0.06)2Al4O8.94. Sr2+ for Bi3+ substitution is probably associated with formation of vacancies of oxygen atoms bridging the tetrahedral dimers. Hopping of oxygen atoms towards the vacancies should strongly enhance the oxygen conductivity. Actually the conductivity is rather low (σ = 7 · 10−
2 S m−
1 at 1073 K, 800°C). An explanation could be the low thermal stability of Sr-doped Bi2Al4O9, especially in coexistence with liquid Bi2O3. Therefore, Bi2Al4O9 single crystals and polycrystalline ceramics both with significant amounts of M
2+ doping (M = Ca2+, Sr2+) have not been produced yet. Thus the question whether or not M
2+-doped Bi2
M
4O9 is an oxygen conducting material is still open.
Thermal expansion and elastic properties of mullite-type Bi2Ga4O9 and Bi2Fe4O9 single crystals
Authors: Krenzel Thomas F. , Schreuer Jürgen , Gesing Thorsten M. , Burianek Manfred , Mühlberg Manfred , Schneider Hartmut
Published: May 2012

Resonant ultrasound spectroscopy was used to characterize the elastic properties of single crystal orthorhombic Bi2Ga4O9 and Bi2Fe4O9 between room temperature and about 1200 K. Additionally, the coefficients of thermal expansion were studied in the range 100 K to 1280 K using high-resolution dilatometry and X-ray powder diffraction. The elastic constants at 295 K are in GPa c
11 = 143.4(1), c
22 = 161.9(1), c
33 = 224.5(1), c
44 = 68.4(1), c
55 = 49.3(1), c
66 = 76.6(1), c
12 = 74.2(1), c
13 = 62.2(1), c
23 = 70.5(1) for Bi2Ga4O9, and c
11 = 106.7(1), c
22 = 141.2(1), c
33 = 183.7(2), c
44 = 53.7(1), c
55 = 41.9(1), c
66 = 63.8(1), c
12 = 63.5(1), c
13 = 59.8(1), c
23 = 63.4(2) for Bi2Fe4O9. In both mullite-type compounds the strong bond chains built up by edge-sharing coordination octahedra extending parallel to [001] dominate the anisotropy of their elastic and thermoelastic properties. Smaller variations of elastic anisotropy within the (001) plane can be attributed to the specific type of cross-linking of the octahedral chains. The temperature evolution of the c

ij
shows no hint on any structural instability or glass-like transition that might be related to the suspected ion conductivity at high temperatures. However, in both crystal species characteristic anelastic relaxation phenomena occur in the ultrasonic frequency regime close to room temperature. The smallest thermal expansion is observed in the plane perpendicular to the stiffest octahedral chains. A model is discussed to explain the apparent discrepancy in terms of cross-correlations within the three-dimensional framework of edge- and corner-linked coordination polyhedra.
New pressure induced phase transitions in mullite-type Bi2(Fe4
–

x
Mn
x
)O10
–
δ complex oxides
Authors: Kalita Patricia E. , Cornelius Andrew L. , Lipinska Kristina E. , Lufaso Michael W. , Kann Zachary R. , Sinogeikin Stanislav , Hemmers Oliver A. , Schneider Hartmut
Published: May 2012

Single phased mullite-type Bi2Fe4
–

x
Mn
x
O10
–

δ
mixed crystals (0.25 ≤ x ≤ 3.125) and the end-member Bi2Fe4O9, synthesized from the oxides by reaction sintering up to 825°C, were studied at high-pressures in order to probe their high-pressure behavior and any possible structural phase transitions. In-situ synchrotron radiation-based powder X-ray diffraction was carried out in a diamond anvil cell, under quasi-hydrostatic conditions, up to a pressure of about 20 GPa at room temperature for each sample. A pressure-induced phase transition was found in all samples. The transition appeared spread over a pressure range and was not completed at the top investigated pressure. This is the first report of a pressure-induced phase transition in Bi2Fe4
–

x
Mn
x
O10
–

δ
mixed crystals.
Orientation relationship between 14H-LPSO structured X phase and DO3-type (Mg,Zn)3RE phase in an Mg–Gd–Y–Zn–Zr alloy
Authors: Zhang Song , Yuan Guangyin , Lu Chen , Ding Wenjiang
Published: May 2012

Mg-10Gd-3Y-1.8Zn-0.5Zr (wt.%) alloy is prepared by permanent mold casting and further by slow solidification at cooling rate of 0.1 K s−
1. Both X phase with long period stacking ordered structure and DO3-type (Mg,Zn)3
RE phase in the alloy are observed with electron microscopy and X-ray diffraction. Three different X phase/(Mg,Zn)3
RE phases are observed in the alloy. The orientation relationship between X phase and (Mg,Zn)3
RE phase was determined by the composite diffraction patterns, which can be expressed as (0014)X phase//(110)(
Mg,Zn
)3RE and [110]X phase//[3 32](
Mg,Zn
)3RE, (0014)X phase//(110)(
Mg,Zn
)3RE and [110]X phase//[1 11](
Mg,Zn
)3RE, (0014)X phase//(110)(
Mg,Zn
)3RE and [210]X phase//[1 12](
Mg,Zn
)3RE. These results show coherence between X phase and (Mg,Zn)3
RE phase and a very small mismatch in the phase boundaries.
Surface structure of different interstitial austenitic steels after impact wear
Authors: Petrov Yuri
Published: May 2012

Effects of carbon and nitrogen on the structure of surface layers in high and low interstitial austenitic steels after impact wear were studied. It was shown that a fully amorphous surface layer appears in high-interstitial stainless steel. Decreasing interstitials content in austenite causes transition from the amorphous to a nanocrystal structure at the top surface. A possible mechanism of surface structure formation in these materials was considered in the frame of vacancy–interstitial interaction theory.
Light, multi-layer, screening textiles with a high capacity for absorbing electromagnetic fields in the high frequency range
Authors: Brzeziński Stefan , Rybicki Tomasz , Karbownik Iwona , Malinowska Grażyna
Published: May 2012

This paper concerns multilayer, shielding textile-polymeric materials with a high shielding effectiveness. This effectiveness is characterised by a high capability to absorb electromagnetic fields as a result of intensification of multiple internal reflections at the boundaries between the layers of component materials. These new shielding materials present low thicknesses and surface weights, amounting to 1.0–2.0 mm and 190–420 g m−
2, respectively, depending on their structures. Such materials composed of various structures, containing various functional particles, meet high requirements of shielding effectiveness within the frequency range tested from 8.0 to 18.0 GHz. Their absorption coefficient is at a level of ≥ 30%, and in some structures it even exceeds 90%, while the reflection coefficient is ≤ 20% and that of transmission amounts to as low as ≤ 20%, approaching even below 2%.
Effect of alloying elements on stage-III work-hardening behaviour of Al–Zn–Mg(–Cu) alloys
Authors: Westermann Ida , Hopperstad Odd Sture , Marthinsen Knut , Holmedal Bjørn
Published: May 2012

Four commercial Al–Zn–Mg(–Cu) alloys have been investigated with respect to the age-hardening response and how the stage-III work-hardening behaviour is influenced by the alloying elements. Tensile specimens of the as-cast and homogenized alloys have been exposed to a solution heat treatment and a two-step age-hardening treatment with varying time at the final temperature. The work-hardening parameters obtained by fitting an extended Voce equation to the experimental stress–strain curves have been analysed and discussed. Addition of Cu was found to increase the strength, whereas Mg seemed to be a limiting factor in age-hardening potential. Accelerated precipitation kinetics was observed when the Zn content was increased.
Microstructural study of boron-doped Co–Re–Cr alloys by means of transmission electron microscopy and electron energy-loss spectroscopy
Authors: Bölitz Marie-Christin , Brunner Martin , Völkl Rainer , Mukherji Debashis , Roesler Joachim , Glatzel Uwe
Published: May 2012

The development of corrosion-resistant alloys with sustained thermal and mechanical stabilities is the focus of current research on high-temperature alloys. It has been shown that the creep behavior and oxidation resistance of Co–Re alloys can be improved by small additions of, e.g., B and Zr. To understand the effect of these elements on mechanical properties, we have characterized the phases and microstructures in the Co–Re–Cr system using transmission electron microscopy. Zr forms isolated large crystals in the matrix, while B is accommodated in small intergranular (Cr,Re)2B borides. The incorporation of up to 23 at.% Re into the Cr2B structure results in increased unit cell constants. The elongated borides occur pervasively along grain boundaries, suggesting that they improve the grain boundary cohesion and thereby the mechanical properties of Co–Re–Cr alloys.
Microstructural, optical, and dielectric properties of nanocrystalline TiO2 films prepared via ion-assisted magnetron sputtering
Authors: Sarma Bimal K. , Pal Arup R. , Bailung Heremba , Chutia Joyanti
Published: May 2012

TiO2 films were deposited on radio-frequency-biased substrates via direct current magnetron sputtering. Argon and oxygen were used as working and reactive gases, respectively. Ions produced in the plasma are accelerated towards the substrates due to the self-bias developed at the substrates. X-ray diffraction and atomic force microscopy reveal that as-deposited films are amorphous with low surface roughness and broad, low-intensity rutile peaks are observed for the films deposited with low bias (self bias ≤ −100 V) at low substrate temperature. The optical study shows blue shift in the band gap for the films deposited with substrate bias. The structural characterization, optical analysis, and dielectric properties confirm the possible coexistence of amorphous and rutile phases in the films deposited with low-biased substrate. These films are useful as optical coatings.
The Mg–C phase equilibria and their thermodynamic basis
Authors: Chen Hai-Lin , Schmid-Fetzer Rainer
Published: May 2012

The Mg–C binary phase equilibria and thermodynamic data are critically evaluated in this work. The necessity is demonstrated to meticulously evaluate the original experimental literature instead of relying on erroneous statements in a previous review that had led to a completely different phase diagram. The two Mg carbides, Mg2C3and MgC2, are both shown to be metastable based on the examination of the thermodynamic data and the original experimental work on their formation and decomposition. Using the Calphad method, a thermodynamic description of the Mg–C system is developed. The stable phase diagram at 1 bar was calculated without assuming any binary interaction parameters. The solubilities of C in liquid Mg, having recently been measured to be tens of ppm between 800°C and 900°C, verify the calculated phase diagram. The metastable Mg2C3and MgC2phases were also modeled and their descriptions were directly derived from the thermodynamic data. The complete Mg–C description allows the calculation of metastable phase equilibria involving these carbides by suspending graphite and diamond.
Thermodynamic description of the system Cu–Sn–P experimental and numerical investigation
Authors: Grasser Monika , Ludwig Andreas , Schillinger Wolfram
Published: May 2012

The aim of the presented experimental and numerical investigation is to verify the ternary phase diagram Cu–Sn–P in the Cu-rich corner, especially the presence and position of the ternary eutectic transition point. Annealing experiments within a concentration gradient have been performed and compared to computational thermodynamics. The identification of phases and phase regions is based on differential thermal analysis, scanning electron and light microscopy. The discussed ternary eutectic transition in the Cu-rich corner is confirmed, phases and phase regions, as proposed by computational thermodynamics, are verified. In addition, the existence of the γ phase was confirmed but the ∊ phase was not found in the as-cast microstructures which decreases its importance for technical bronze alloys with Sn up to a mass fraction of 0.2.
Isochronal annealing of a deformed Fe-7.5 mass.% Si-steel
Authors: Cámara Fernando González , Mostafa K. haled M. , Petrov Roumen , Rodríguez-Calvillo Pablo , De Grave Eddy , Segers Danny , Houbaert Y. van
Published: May 2012

FeSi samples with 7.5 mass.% Si were cold deformed with a thickness reduction of 16% and isochronally annealed for one hour at different temperatures. Their microstructure was characterised using positron annihilation lifetime spectroscopy and electron backscatter diffraction.

Positron annihilation mean lifetime values (τmean) decreased slightly with the increase in annealing temperature (20 to 600°C), a process related to recovery. In addition, τmean decreased significantly in the 700–900°C temperature range. The measured value of τmean is 106 ps, which is similar to the pure undeformed Fe after annealing at 900°C. Thus, the material is virtually free of defects at 900°C. Microscopy and diffraction studies showed a high amount of shear bands for the deformed sample. In the temperature range of 20–600°C, no recrystallisation was observed. According to the electron backscatter diffraction data, the recrystallisation starts after 700°C, and it is completed at 900°C.
Caryophyllaeid infestations on the sex and size of Walking Catfish Clarias batrachus
Authors: Chhanda MS , Chandra KJ
Published: May 2012

An investigation was carried out on the caryophyllaeid infestations in walking catfish Clarias batrachus in relation to different sexes and size groups during August 2010 to July 2011. A total of 227 host fish were collected from different water bodies of Mymensingh for examination. Among them 188 C.batrachus were infested with 1432 parasites by five different caryophyllaeid cestodes species. Prevalence was 100% during November and December both in male and female hosts. In other period of the year, female were more infested. In male fishes, the highest intensity and abundance were recorded in December and index of infection in February. In female fishes, the lowest infestations were recorded during the months of August, September and October. Parasites showed different levels of infestations in different size groups of fishes. Higher prevalence was recorded in medium size fishes in winter and summer and smaller size fishes in autumn. However, the index of infestations and abundance were higher in same size group only in winter season. The lowest prevalence and mean intensity were recorded in rainy season and abundance was in summer in smaller size group of fish.DOI: http://dx.doi.org/10.3329/bjas.v40i1-2.10792Bang. J. Anim. Sci. 2011. 40 (1-2): 56-59
Polydimethylsiloxane (PDMS) Coating onto Magnetic Nanoparticles Induced by Attractive Electrostatic Interaction
Authors: Sötebier Carina , Michel Aude , Fresnais Jérôme
Published: May 2012

In this article, we present an efficient synthesis pathway of polydimethylsiloxane (PDMS) coated magnetic nanoparticles from hydrophilic polyacrylate coated ferrofluids (NPPAA). A block copolymer based on polydimethylsiloxane is selected for its propensity to interact with the carboxylate functions on the NPPAA. The interaction is due to negative charges on NPPAA and positive ones on the amphiphilic copolymer. The synthesis is achieved by interfacial interaction, simplifying the purification of the PDMS-coated nanoparticles (NPPDMS) from subproducts such as ions and water. NPPDMS are well dispersed in hydrophobic solvents (toluene, diethyl ether) and can then be embedded into a curable PDMS polymer.
Structural Stability and Performance of Noble Metal-Free SnO2-Based Gas Sensors
Authors: Tricoli Antonio
Published: May 2012

The structural stability of pure SnO2 nanoparticles and highly sensitive SnO2-SiO2 nanocomposites (0–15 SiO2 wt%) has been investigated for conditions relevant to their utilization as chemoresistive gas sensors. Thermal stabilization by SiO2 co-synthesis has been investigated at up to 600 °C determining regimes of crystal size stability as a function of SiO2-content. For operation up to 400 °C, thermally stable crystal sizes of ca. 24 and 11 nm were identified for SnO2 nanoparticles and 1.4 wt% SnO2-SiO2 nanocomposites, respectively. The effect of crystal growth during operation (TO = 320 °C) on the sensor response to ethanol has been reported, revealing possible long-term destabilization mechanisms. In particular, crystal growth and sintering-neck formation were discussed with respect to their potential to change the sensor response and calibration. Furthermore, the effect of SiO2 cosynthesis on the cross-sensitivity to humidity of these noble metal-free SnO2-based gas sensors was assessed.
Exposure Estimation from Multi-Resolution Optical Satellite Imagery for Seismic Risk Assessment
Authors: Wieland Marc , Pittore Massimiliano , Parolai Stefano , Zschau Jochen
Published: May 2012

Given high urbanization rates and increasing spatio-temporal variability in many present-day cities, exposure information is often out-of-date, highly aggregated or spatially fragmented, increasing the uncertainties associated with seismic risk assessments. This work therefore aims at using space-based technologies to estimate, complement and extend exposure data at multiple scales, over large areas and at a comparatively low cost for the case of the city of Bishkek, Kyrgyzstan. At a neighborhood scale, an analysis of urban structures using medium-resolution optical satellite images is performed. Applying image classification and change-detection analysis to a time-series of Landsat images, the urban environment can be delineated into areas of relatively homogeneous urban structure types, which can provide a first estimate of an exposed building stock (e.g., approximate age of structures, composition and distribution of predominant building types). At a building-by-building scale, a more detailed analysis of the exposed building stock is carried out using a high-resolution Quickbird image. Furthermore, the multi-resolution datasets are combined with census data to disaggregate population statistics. The tools used within this study are being developed on a free- and open-source basis and aim at being transparent, usable and transferable.