bluuebunny/crossref_metadata_2025 huggingface dataset:
Low Sintering Temperature Microwave Dielectric Ceramics and Composites Based on Bi2O3 –B2O3
Authors: Chen Xingyu , Zhang Weijun , Zalinska Beata , Sterianou Iasmi , Bai Shuxin , Reaney Ian M.
Published: June 2012

Phase evolution, sintering behavior, and microwave dielectric properties of compounds within the
Bi

2

O

3–
B

2

O

3 phase diagram have been investigated. Two promising ceramics,
Bi

6

B

10

O

24 and
Bi

4

B

2

O

9, were fabricated which densified at 700°C and 660°C with permittivity, εr = 10 and 39, microwave quality factor, Qf
0 = 10800 and 2600 GHz, and temperature coefficient of resonant frequency, τf = −41 and −203 ppm/oC, respectively. The unusually large –ve τf, high εr and reasonable values of Qf
0 of
Bi

4

B

2

O

9 coupled with its low sintering temperature suggested that it may be useful in the fabrication of temperature‐stable composites with high εr, +ve τf end members. Composites were, therefore, fabricated of x

Bi

4

B

2

O

9 with (1−x)
BaNd

2

Ti

4

O

12 (x

BB
–
BNT
), and (1−x)[0.2
CaTiO

3−0.8(
Li

0.5

Nd

0.5)
TiO

3] (x

BB
–
CTLNT
), respectively (x is in wt%). In each case, the sintering temperature to achieve > 95% theoretical density was reduced by ≥150°C to 1200°C. Optimum properties were achieved for 0.075
BB
–
BNT
with εr = 86, Qf
0 = 5400 GHz, and τf = 4 ppm/°C, and for 0.04
BB
–
CTLNT
with εr = 127, Qf
0 = 2700 GHz, and τf = −4 ppm/°C. Unusually for composites, Qf
0 did not significantly deteriorate and εr increased markedly with respect to the high‐permittivity end‐member for composites with x < 0.1. Optimized compositions are suitable for applications in dielectrically loaded antennas and in C0G high‐frequency filter applications.
Luminescent Properties of Praseodymium in CaWO4 Matrix
Authors: Wu Haoyi , Hu Yihua , Kang Fengwen , Li Nana , Ju Guifang , Mu Zhongfei , Yang Zhongfu
Published: June 2012

Praseodymium (Pr3+) with rich f energy levels can generate various visible emissions, but the luminescence of Pr3+ in a CaWO4 matrix has not yet been studied. In this article, the phosphors of Pr3+‐doped CaWO4 were synthesized via a high temperature solid‐state reaction, and the photoluminescence (PL) and afterglow properties of Pr3+ in the CaWO4 matrix were investigated. The phase identifications of the samples show that an impure monoclinic phase appears when the Pr3+ concentration is high. The results of PL exhibit the usual Pr3+ characteristic emissions as well as an emission that is produced by the charge transfer from 5d of W6+ to 2p of O2− under a shortwave ultraviolet excitation. An intermediate energy transfer occurs during the charge transfer which induces the afterglow. The quenching point of Pr3+ in CaWO4 is 2 mol%, corresponding to the critical energy transfer distance of ~20 Å. The quenching mechanism in the Pr3+‐doped CaWO4 is the dipole‐dipole interaction. The Ca2+ vacancies (VCa) are the defects that induce the traps and capture holes from O2−. The thermal energy of holes liberation from VCa to O2− results in the charge transfer accompanied by an energy transfer to Pr3+, and consequently generates the afterglow. The experimental results also show that the afterglow characteristics of Pr3+ are prolonged by incorporating Pr3+ in the CaWO4 matrix.
Nanocrystallization of TiO2 Anatase Phase in Hydrophobic BaO–TiO2–B2O3 Glass System
Authors: Paramesh Gadige , Varma Kalidindi B. R.
Published: June 2012

Transparent colorless glasses in the ternary BaO–TiO2–B2O3 system were fabricated via conventional melt‐quenching technique. The glasses with certain molar concentrations of BaO and TiO2 on heat treatment at appropriate temperatures yielded nanocrystalline phase of TiO2 associated with the crystallite size in the 5–15 nm range. Nanocrystallized glasses exhibited high refractive index (n = 2.15) measured at λ = 543 nm. These glasses were found to be hydrophobic in nature associated with the contact angle of 90o. These high‐index glass nanocrystal composites would be of potential interest for optical device applications.
Dietary pattern and oral cancer risk – a factor analysis study
Authors: Helen‐Ng Lee Ching , Razak Ishak A. , Ghani Wan Maria Nabillah , Marhazlinda Jamaluddin , Norain Abdul Talib , Raja Jallaludin Raja‐Latifah , Rahman Zainal Ariff Abdul , Abdullah Norlida , Zain Rosnah B.
Published: June 2012

Objectives

The role of diet in cancer risk has mainly been investigated based on intake of individual food items. However, food consumption is made up of a combination of various food items. This study aims to determine the association of dietary patterns with oral cancer risk.

Methods

A total of 306 matched cases and controls were recruited in this study. Data on dietary intake were obtained using food frequency questionnaire (FFQ). Factor analysis (FA) was performed to identify dietary patterns based on the intake of nine major food groups, resulting in four factors/components being retained. The odds ratio (OR) was computed for each component using conditional logistic regression.

Results

The first pattern labelled as ‘modern’ was loaded with processed foods and snacks, whereas the second pattern termed as ‘prudent’ was characterized by intake of fruits and vegetables. The third pattern labelled as ‘traditional’ consisted of beverages and starches, while the fourth pattern termed as ‘combination’ was loaded with intakes of dairy, fermented/salted and meat/by‐products. A significant reduced risk was found for ‘prudent’ (OR 0.53, 95% CI = 0.28–0.98), whereas an increased risk was found for both ‘combination’ (OR 2.43, 95% CI = 1.33–4.45) and ‘traditional’ (OR 2.32, 95% CI = 1.23–4.25) patterns. However, after adjusting for risk habits of tobacco smoking, alcohol consumption and betel quid chewing, only ‘combination’ (aOR 2.99, 95% CI = 1.55–5.75) and ‘traditional’ (aOR 2.08, 95% CI = 1.09–3.97) patterns remained significant.

Conclusion

Consumption in the highest tertile of ‘traditional’ and ‘combination’ patterns may induce twice and thrice the risk of oral cancer, respectively.
Contact allergy to air‐exposed geraniol: clinical observations and report of 14 cases
Authors: Hagvall Lina , Karlberg Ann‐Therese , Bråred Christensson Johanna
Published: June 2012

Background. The fragrance terpene geraniol forms sensitizing compounds via autoxidation and skin metabolism. Geranial and neral, the two isomers of citral, are the major haptens formed in both of these activation pathways.

Objectives. To investigate whether testing with oxidized geraniol detects more cases of contact allergy than testing with pure geraniol.

Patients and methods. The pattern of reactions to pure and oxidized geraniol, and metabolites/autoxidation products, was studied to investigate the importance of autoxidation or cutaneous metabolism in contact allergy to geraniol. Pure and oxidized geraniol were tested at 2.0% petrolatum in 2227 and 2179 consecutive patients, respectively. In parallel, geranial, neral and citral were tested in 2152, 1626 and 1055 consecutive patients, respectively.

Results. Pure and oxidized geraniol gave positive patch test reactions in 0.13% and 0.55% of the patients, respectively. Eight of 11 patients with positive patch test reactions to oxidized geraniol also reacted to citral or its components. Relevance for the positive patch test reactions in relation to the patients' dermatitis was found in 11 of 14 cases.

Conclusions. Testing with oxidized geraniol could detect more cases of contact allergy to geraniol. The reaction pattern of the 14 cases presented indicates that both autoxidation and metabolism could be important in sensitization to geraniol.
Assessing the severity of allergic reactions: a regulatory dilemma
Authors: Basketter David A. , McFadden John P. , Kimber Ian
Published: June 2012

The identification of chemicals possessing the intrinsic ability to cause sensitization via skin contact or inhalation, commonly referred to as skin and respiratory sensitizers, is a key endpoint in regulatory toxicology. Predictive assays for this purpose exist only for skin sensitizers, but, for both types of sensitizer, human evidence can be used to determine whether a substance should be classified. Furthermore, the use of human evidence for subcategorization according to sensitization potency is also accommodated within the regulations. Normally, this is based on the prevalence of sensitization in relation to the degree of exposure in the context of the size of the population exposed. However, the regulations also indicate that the severity of (allergic) reactions may be taken into account. In this article, we consider whether this is appropriate and whether there is evidence that reaction severity can inform decisions on classification and/or potency categorization. The conclusion drawn is that the severity of an allergic reaction does not correlate with, or serve as an indicator of, the sensitizing potency of a chemical. In reality, it reflects the overall extent of sensitization that an individual has acquired, in concert with the concentration of the causative allergen to which they have been exposed.
In vitro evaluation of the suppressor potential of conditioned medium from benign myoepithelial cells from pleomorphic adenoma in malignant cell invasion
Authors: da Silva Alessandra Dutra , Silva Carolina Amália Barcellos , Montalli Victor Angelo Martins , Martinez Elizabeth Ferreira , de Araújo Vera Cavalcanti , Furuse Cristiane
Published: June 2012

J Oral Pathol Med (2012) 41: 610–614

Tumoral invasion process is the result of a complex interaction between the tumor cells and microenvironment which plays an important role in modulating the growth and invasion of the cancer. The myoepithelial cells, present in glandular organs such as the breast and salivary glands, seem to exert paracrine effects on the glandular epithelium, acting as natural tumor suppressors. To verify the influence of the benign myoepithelial cells in the invasion of malignant cells, simulating an in situ carcinoma ex pleomorphic adenoma, we have cultured three different high‐potential invasive malignant tumors (breast ductal adenocarcinoma, melanoma and oral squamous cell carcinoma) in conditioned medium of myoepithelial cells from salivary gland pleomorphic adenomas using transwell chambers with 8‐μm pores membrane coated with matrigel. After 96 h, quantitative analyses of the results were performed by calculating the invasion index (number of cells that invaded in relation to the total number of cells). The results showed that there was a reduction of the invasion index mean for the three different malignant tumors. This study supports a tumoral suppressor function of the myoepithelial cells from pleomorphic adenoma in in vitro invasion process.
Oral and Genital Human Herpesvirus 8 and Human Papillomavirus in heterosexual partners
Authors: da Mota Vasconcelos Brasil Catarina , Ribeiro Camila Maria Beder , Leão Jair Carneiro
Published: June 2012

Background:  The purpose of this study was to verify a possible co‐infection of human herpesvirus 8 (HHV‐8) in commonly associated human papillomavirus (HPV) penile lesions and to determine the frequency of detection of these viruses in the oral mucosa of their female counterparts.

Methods:  Thirty‐one male subjects underwent penile swabs from clinical HPV‐related lesions. Their female counterparts underwent swabs of the vagina, uterine cervix, and oral mucosa. HPV and HHV‐8 detection was performed by polymerase chain reaction using the consensus primers MY11/MY09 and KS1/KS2, respectively.

Results:  HPV DNA was detected in 31/31 penile lesions. HPV DNA was also detected in 18/31 (58%) female genital brushings and 17/31 (54%) female oral brushings. HHV‐8 DNA was detected in 1/31 (3.2%) male genital brushings and 3/31 (9.6%) female oral mucosa brushings. None of the female genital brushings were HHV‐8 DNA‐infected.

Conclusions:  Based upon the results of this study, co‐infection between HPV and HHV‐8 in malignant and pre‐malignant penile lesions is an unlikely finding.
Sarcolemmal Repair Is a Slow Process and Includes EHD2
Authors: Marg Andreas , Schoewel Verena , Timmel Tobias , Schulze Anne , Shah Claudio , Daumke Oliver , Spuler Simone
Published: June 2012

Skeletal muscle is continually subjected to microinjuries that must be repaired to maintain structure and function. Fluorescent dye influx after laser injury of muscle fibers is a commonly used assay to study membrane repair. This approach reveals that initial resealing only takes a few seconds. However, by this method the process of membrane repair can only be studied in part and is therefore poorly understood. We investigated membrane repair by visualizing endogenous and GFP‐tagged repair proteins after laser wounding. We demonstrate that membrane repair and remodeling after injury is not a quick event but requires more than 20 min. The endogenous repair protein dysferlin becomes visible at the injury site after 20 seconds but accumulates further for at least 30 min. Annexin A1 and F‐actin are also enriched at the wounding area. We identified a new participant in the membrane repair process, the ATPase EHD2. We show, that EHD2, but not EHD1 or mutant EHD2, accumulates at the site of injury in human myotubes and at a peculiar structure that develops during membrane remodeling, the repair dome. In conclusion, we established an approach to visualize membrane repair that allows a new understanding of the spatial and temporal events involved.
OCRL1Modulates Cilia Length in Renal Epithelial Cells
Authors: Rbaibi Youssef , Cui Shanshan , Mo Di , Carattino Marcelo , Rohatgi Rajeev , Satlin Lisa M. , Szalinski Christina M. , Swanhart Lisa M. , Fölsch Heike , Hukriede Neil A. , Weisz Ora A.
Published: June 2012

Lowe syndrome is an X‐linked disorder characterized by cataracts at birth, mental retardation and progressive renal malfunction that results from loss of function of theOCRL1(oculocerebrorenal syndrome of Lowe) protein.OCRL1is a lipid phosphatase that converts phosphatidylinositol 4,5‐bisphosphate to phosphatidylinositol 4‐phosphate. The renal pathogenesis of Lowe syndrome patients has been suggested to result from alterations in membrane trafficking, but this cannot fully explain the disease progression. We found that knockdown ofOCRL1in zebrafish caused developmental defects consistent with disruption of ciliary function, including body axis curvature, pericardial edema, hydrocephaly and impaired renal clearance. In addition, cilia in the proximal tubule of the zebrafish pronephric kidney were longer inocrlmorphant embryos. We also found that knockdown ofOCRL1in polarized renal epithelial cells caused elongation of the primary cilium and disrupted formation of cysts in three‐dimensional cultures. Calcium release in response toATPwas blunted inOCRL1knockdown cells, suggesting changes in signaling that could lead to altered cell function. Our results suggest a new role forOCRL1in renal epithelial cell function that could contribute to the pathogenesis of Lowe syndrome.
American Grace: The Theological Price
Authors: Flanagan Kieran
Published: June 2012

The study, American Grace by Putnam and Campbell affirms the sociological significance of religion as a distinctive vitalising form of social capital. With its stress on virtues of trust, altruism and communal affiliation realised through social networking in congregations, this civil religion, one peculiar to the U.S.A., accomplishes a form of grace that resolves the puzzle of belief and pluralism by generating harmony and religious tolerance. This solution bears a price of rendering religion as end in itself, one detached from exclusivist theological claims in regard to salvation. In exposing this conundrum, the study reveals a highly significant and unexpected facet of the secularisation thesis.
Identification of quantitative trait loci for rice grain element composition on an arsenic impacted soil: Influence of flowering time on genetic loci
Authors: Norton G.J. , Duan G.-L. , Lei M. , Zhu Y.‐G. , Meharg A.A. , Price A.H.
Published: June 2012

Elements in grain crops such as iron, zinc and selenium are essential in the human diet, whereas elements such as arsenic are potentially toxic to humans. This study aims to identify quantitative trait loci (QTLs) for trace elements in rice grain. A field experiment was conducted in an arsenic enriched field site in Qiyang, China using the Bala × Azucena mapping population grown under standard field conditions. Grains were subjected to elemental analysis by inductively coupled plasma mass spectroscopy. QTLs were detected for the elemental composition within the rice grains, including for iron and selenium, which have previously been detected in this population grown at another location, indicating the stability of these QTLs. A correlation was observed between flowering time and a number of the element concentrations in grains, which was also revealed as co‐localisation between flowering time QTLs and grain element QTLs. Unravelling the environmental conditions that influence the grain ionome appears to be complex, but from the results in this study one of the major factors which controls the accumulation of elements within the grain is flowering time.
Salicylic acid‐mediated elicitation of tomato defence against infection by potato purple top phytoplasma
Authors: Wu W. , Ding Y. , Wei W. , Davis R.E. , Lee I.‐M. , Hammond R.W. , Zhao Y.
Published: June 2012

Recent outbreaks and continued spread of diseases caused by phytoplasmas in potato, tomato and other vegetable crops in the USA accentuates the need for practical strategies to mitigate the impact of the phytoplasmal diseases. The purpose of this study was to investigate whether exogenous application of salicylic acid (SA) on healthy tomato seedlings would enhance the plants' defence against a subsequent potato purple top (PPT) phytoplasma infection. Our results showed that a twice‐applied SA pretreatment, at 4 and 2 days before phytoplasma inoculation, significantly decreased the rate of PPT phytoplasma infection and reduced disease symptoms. At 40 days postinoculation (dpi), while 94% of the PPT phytoplasma‐inoculated control plants exhibited characteristic PPT symptoms, 53% of the SA‐pretreated, PPT phytoplasma‐inoculated plants remained symptom‐free with no molecular evidence of phytoplasma infection. The remaining 47% of SA‐treated plants became infected, but symptoms were much milder and the average phytoplasma titre was more than 300 times lower compared with that in control plants. Real‐time qRT‐PCR assays revealed that SA‐pretreatment caused transcriptional reprogramming of three defence‐related genes. Up‐regulations of a WRKY‐type transcriptional factor gene (LeWRKY1) and a mitogen‐activated protein kinase gene (LeMPK3) in an early stage following graft inoculation, and a sustained higher level expression of a downstream pathogenesis‐related protein gene (LePRP1), were observed in SA‐pretreated, PPT phytoplasma‐inoculated plants. With the dosage and treatment regime implemented in this study, no noticeable phytotoxic effects or other negative impact on vegetative growth or reproductive development was observed in SA‐treated plants throughout our experiment. Our findings encourage field trials of SA pretreatment as a possible approach to protect crops from phytoplasmal diseases.
sGC stimulation totally reverses hypoxia‐induced pulmonary vasoconstriction alone and combined with dual endothelin‐receptor blockade in a porcine model
Authors: Lundgren J. , Kylhammar D. , Hedelin P. , Rådegran G.
Published: June 2012

Aim

Stimulation of soluble guanylate cyclase (sGC) with BAY 41‐8543 was hypothesized to attenuate acute hypoxic pulmonary vasoconstriction alone and combined with dual endothelin (ET)‐receptor antagonist tezosentan.

Methods

Measurements were taken in 18 anaesthetized pigs with a mean ± SEM weight of 31.1 ± 0.4 kg, in normoxia (FiO2~0.21) and hypoxia (FiO2~0.10) without (control protocol, n = 6), and with right atrial infusion of BAY 41‐8543 at 1, 3, 6, 9 and 12 μg min−1per kg (protocol 2, n = 6) or tezosentan at 5 mg kg−1 followed by BAY 41‐8543 at 1, 3 and 6 μg min−1per kg (protocol 3, n = 6).

Results

Hypoxia (n = 18) increased (P < 0.001) mean pulmonary artery pressure (MPAP) and pulmonary vascular resistance (PVR) by 14.2 ± 0.6 mmHg and 2.8 ± 0.3 WU respectively. During sustained hypoxia without treatment, MPAP and PVR remained stable. BAY 41‐8543 (n = 6) dose‐dependently decreased (P < 0.001) MPAP and PVR by 15.0 ± 1.2 mmHg and 4.7 ± 0.7 WU respectively. Tezosentan (n = 6) decreased (P < 0.001) MPAP and PVR by 11.8 ± 1.2 mmHg and 2.0 ± 0.2 WU, respectively, whereafter BAY 41‐8543 (n = 6) further decreased (P < 0.001) MPAP and PVR by 6.6 ± 0.9 mmHg and 1.9 ± 0.4 WU respectively. Both BAY 41‐8543 and tezosentan decreased (P < 0.001) systemic arterial pressure and systemic vascular resistance. Blood‐O2 consumption remained unaltered (P = ns) during all interventions.

Conclusion

BAY 41‐8543 totally reverses the effects of acute hypoxia‐induced pulmonary vasoconstriction, and enhances the attenuating effects of tezosentan, without affecting oxygenation. Thus, sGC stimulation, alone or combined with dual ET‐receptor blockade, could offer a means to treat pulmonary hypertension related to hypoxia and potentially other causes.
Melanoma revives an embryonic migration program to promote plasticity and invasion
Authors: Bailey Caleb M. , Morrison Jason A. , Kulesa Paul M.
Published: June 2012

Cancer cells must regulate plasticity and invasion to survive and metastasize. However, the identification of targetable mechanisms to inhibit metastasis has been slow. Signaling programs that drive stem and progenitor cells during normal development offer an inroad to discover mechanisms common to metastasis. Using a chick embryo transplant model, we have compared molecular signaling programs of melanoma and their embryonic progenitors, the neural crest. We report that malignant melanoma cells hijack portions of the embryonic neural crest invasion program. Genes associated with neural crest induction, delamination, and migration are dynamically regulated by melanoma cells exposed to an embryonic neural crest microenvironment. Specifically, we demonstrate that metastatic melanoma cells exploit neural crest‐related receptor tyrosine kinases to increase plasticity and facilitate invasion while primary melanocytes may actively suppress these responses under the same microenvironmental conditions. We conclude that aberrant regulation of neural crest developmental genes promotes plasticity and invasiveness in malignant melanoma.
Phylogeographic analysis and environmental niche modeling of widespread shrub Rhododendron simsii in China reveals multiple glacial refugia during the last glacial maximum
Authors: LI Yong , YAN Hai‐Fei , GE Xue‐Jun
Published: June 2012

Abstract  The phylogeography of common and widespread species can help us to understand the history of local flora and vegetation. Here, we study the semi‐evergreen shrub Rhododendron simsii Planch., which is found in most areas of current evergreen broad leaved forest in China. Two noncoding chloroplast DNA (cpDNA) regions (rpl20‐rps12 and trnL‐F) and three amplified fragment length polymorphism (AFLP) primer sets (E‐AAC/M‐CTA, E‐AGC/M‐CTA and E‐AGG/M‐CAT) were used to examine the phylogeographic pattern in relation to past (last glacial maximum) and present distributions based on ecological niche modeling. The cpDNA data revealed four phylogeographic groups (East, South, West, and North groups) corresponding to geographic regions. Molecular dating suggests that lineage diversification within species likely occurred during the mid‐to‐late Pleistocene. In contrast, the four main cpDNA phylogeographic groups were not supported by the AFLP dataset. The highest likelihood of the AFLP data was obtained when samples were clustered into three groups (K= 3). However, these groupings did not correspond to separate geographic regions supported by cpDNA data. Both mismatch distribution analysis and environmental niche modeling (ENM) indicated that multiple glacial refugia were maintained across the range of Rhododendron simsii during the last glacial maximum, contrary to the previous hypothesis that subtropical broad leaved evergreen forests were forced to retreat southward as far as 25° N. The discordance between the patterns revealed by cpDNA and AFLP data indicate that localized postglacial range expansions may facilitate extensive gene flow between the major glacial refugia.
Complete Efficiency Analysis of Epicyclic Gear Train With Two Degrees of Freedom
Authors: Davies Kieran , Chen Chao , Chen Bernard K.
Published: June 2012

Epicyclic gear trains (EGTs) are important mechanical transmissions with many applications. For optimal design and operation of these gear trains, it is necessary to obtain complete efficiency maps of such transmissions. The efficiency of a two degrees of freedom (two-dof) EGT is derived based on the internal power flow and virtual power flow patterns. Expressions for the efficiencies in different operating conditions are obtained and verified by three special conditions.
Computational Model for Investigating the Influence of Unbalanced Magnetic Pull on the Radial Vibration of Large Hydro-Turbine Generators
Authors: Xu Yong , Li Zhaohui
Published: June 2012

A radial unbalanced magnetic pull (UMP) can be produced by an eccentric rotor and leads vibrations in large hydro-turbine generators. The influence of nonlinear UMP on the radial vibration of a large hydro-turbine generator is analyzed in this paper. The UMP is determined as a function of eccentricities and field currents by means of a simple analytical method instead of the finite element (FE) method. The analytical method employs the no-load characteristic curve of an electrical machine and saturation effects of the ferromagnetic materials are taken into consideration. FE rotor model of a large hydro-turbine generator unit, taking account of guide bearings, thrust bearing and periodic forces, is developed to investigate the influence of UMP on radial vibrations. The FE rotor model and the analytical method for UMP constitute the computational model. UMP is calculated under different rotor eccentricities and field currents by the proposed method. Comparing with other analytical methods, the effectiveness of the proposed method is verified. Dynamic responses of the FE model under different analytical methods for UMP are calculated to investigate the difference in vibration between different analytical methods. A simulated excitation test is performed and a comparative analysis between the calculated results and the field data is provided. The computational model is proved to be reasonable according to the analysis.
Comparative Analysis for Low-Mass and Low-Inertia Dynamic Balancing of Mechanisms
Authors: van der Wijk V. , Demeulenaere B. , Gosselin C. , Herder J. L.
Published: June 2012

Dynamic balance is an important feature of high speed mechanisms and robotics that need to minimize vibrations of the base. The main disadvantage of dynamic balancing, however, is that it is accompanied with a considerable increase in mass and inertia. Aiming at low-mass and low-inertia dynamic balancing, in this article the relative importance of the balance parameters of common balancing principles is analyzed and the balancing principles are compared. To do this, the evaluation of a balanced rotatable link is found to be representative for a large group of balanced mechanisms. Therefore, a rotatable link is balanced with duplicate mechanisms (DM), with a countermass (CM) and a separate counter-rotation (SCR), and with a counter-rotary countermass (CRCM). The equations for the total mass and the inertia are derived and compared analytically while the balancing principles are compared numerically. The results show that the DM-balanced link is the best compromise for low mass and low inertia but requires a considerable space. For the CRCM-balanced link and the SCR-balanced link that are more compact, there is a trade-off between mass and inertia for which the CRCM-balanced link is the better of the two.
Traction and Efficiency Performance of the Double Roller Full-Toroidal Variator: A Comparison With Half- and Full-Toroidal Drives
Authors: De Novellis L. , Carbone G. , Mangialardi L.
Published: June 2012

In this paper, we analyze in terms of efficiency and traction capabilities a recently patented toroidal traction drive variator: the so-called double roller full-toroidal variator (DFTV). By employing a relatively simple model of the elastohydrodynamic contact behavior between the disks and rollers, we compare the performance of the DFTV with classical solutions as the single-roller full-toroidal variator (SFTV) and the single-roller half-toroidal variator (SHTV). Interestingly, the DFTV shows an improvement of the mechanical efficiency over a wide range of transmission ratios, and in particular at the unit speed ratio, as in such conditions the DFTV allows for zero-spin thus strongly enhancing its traction capabilities. The relation between the torque transmission and the operational volume is also investigated for the three toroid geometries. In this case, the better performance is achieved by the SHTV, whereas the other two geometries show a similar behavior.
A New Method to Measure Planet Load Sharing and Sun Gear Radial Orbit of Planetary Gear Sets
Authors: Boguski B. , Kahraman A. , Nishino T.
Published: June 2012

A new method of measuring planet load sharing of planetary gear sets is proposed in this paper. The method uses strain gauges mounted directly on the planet pins to measure continuously the loads carried by the planets assembled in a fixed carrier. Example 4-planet gear sets of different planet phasing conditions are procured and tested with a family of planet carriers having various levels and combinations of planet pinhole position errors to demonstrate the measurement method. As the radial floating capability of the central members is critical to planet-to-planet load sharing, a companion proximity-probe based measurement system is also implemented to measure the radial motions of the floating sun gear under various planet phasing and carrier pinhole error conditions. It is shown that both measurement methods are effective in characterizing the loads carried by planets.
Design of a Rehabilitation Device Based on a Mechanical Link System
Authors: Kong Kyoungchul , Tomizuka Masayoshi
Published: June 2012

Realizing an ideal impedance control system in lower extremity rehabilitation systems is challenged by mechanical impedance of robot hardware. Although many researchers in Robotics and Control Systems have studied to reduce the mechanical impedance of actuators, they have not been able to eliminate the inertia of robot hardware. This paper introduces an alternative design using mechanical links. The mechanical links are driven by one actuator without any complicated servo systems. The design parameters were optimized by simulation studies for the link system to generate the normal walking motion. The device is connected to a human using elastic components, and therefore, the inertia of the link system is not directly imposed on the user. The human legs are guided to follow the motion of the link system by an assistive force generated by the elastic components.
Optical and structural characterization of epitaxial graphene on vicinal 6H-SiC(0001)–Si by spectroscopic ellipsometry, Auger spectroscopy, and STM
Authors: Nelson Florence , Sandin Andreas , Dougherty Daniel B. , Aspnes David E. , Rowe Jack E. , Diebold Alain C.
Published: June 2012

The authors report results of spectroscopic ellipsometry (SE) measurements in the near-IR, visible, and near-UV spectral ranges using a Woollam dual rotating-compensator ellipsometer, analyzing data in terms of both epitaxial graphene and interface contributions. The SiC samples were cleaned by standard methods of CMP and HF etching prior to mounting in UHV and growing epitaxial graphene by thermal annealing at ∼1400 °C. Most samples were vicinally cut 3.5° off (0001) toward [11−20]. STM measurements show that the initial regular step edges were replaced by somewhat irregular edges after graphene growth. From growth-temperature and Auger data the authors estimate that the graphene is ∼3–4 ML thick. The authors find significant differences among the spectral features of the interface “buffer” layer and those of graphene. Specifically, the hyperbolic-exciton peak reported previously at ∼4.5 eV in graphene shifts to a similarly shaped peak at ∼4 eV in the interface buffer layer. The authors attribute this shift to a significant component of sp3 bonded carbon in the buffer, which occurs in addition to the sp2 bonded carbon that is present in the graphene layer. SE data in the terahertz range obtained by Hoffman et al. [Thin Solid Films 519, 2593 (2011)] show that the mobility values of graphene grown on the carbon face of SiC vary with proximity to the substrate. This leads to the question as to whether an interface layer at the Si face has properties (i.e., dielectric function/complex refractive index) that are different from and/or affect those of the graphene layers.
Seasonal Diversity of Planktonic Protists in Southwestern Alberta Rivers over a 1-Year Period as Revealed by Terminal Restriction Fragment Length Polymorphism and 18S rRNA Gene Library Analyses
Authors: Thomas Matthew C. , Selinger L. Brent , Inglis G. Douglas
Published: June 2012

The temporal dynamics of planktonic protists in river water have received limited attention despite their ecological significance and recent studies linking phagotrophic protists to the persistence of human-pathogenic bacteria. Using molecular-based techniques targeting the 18S rRNA gene, we studied the seasonal diversity of planktonic protists in Southwestern Alberta rivers (Oldman River Basin) over a 1-year period. Nonmetric multidimensional scaling analysis of terminal restriction fragment length polymorphism (T-RFLP) data revealed distinct shifts in protistan community profiles that corresponded to season rather than geographical location. Community structures were examined by using clone library analysis; HaeIII restriction profiles of 18S rRNA gene amplicons were used to remove prevalent solanaceous plant clones prior to sequencing. Sanger sequencing of the V1-to-V3 region of the 18S rRNA gene libraries from spring, summer, fall, and winter supported the T-RFLP results and showed marked seasonal differences in the protistan community structure. The spring library was dominated by Chloroplastidae (29.8%), Centrohelida (28.1%), and Alveolata (25.5%), while the summer and fall libraries contained primarily fungal clones (83.0% and 88.0%, respectively). Alveolata (35.6%), Euglenozoa (24.4%), Chloroplastida (15.6%), and Fungi (15.6%) dominated the winter library. These data demonstrate that planktonic protists, including protozoa, are abundant in river water in Southwestern Alberta and that conspicuous seasonal shifts occur in the community structure.
Higher-Level Production of Volatile Fatty Acids
In Vitro
by Chicken Gut Microbiotas than by Human Gut Microbiotas as Determined by Functional Analyses
Authors: Lei Fang , Yin Yeshi , Wang Yuezhu , Deng Bo , Yu Hongwei David , Li Lanjuan , Xiang Charlie , Wang Shengyue , Zhu Baoli , Wang Xin
Published: June 2012

The aim of this study was to determine the relationship between the composition and function of gut microbiota. Here, we compared the bacterial compositions and fermentation metabolites of human and chicken gut microbiotas. Results generated by quantitative PCR (qPCR) and 454 pyrosequencing of the 16S rRNA gene V3 region showed the compositions of human and chicken microbiotas to be markedly different, with chicken cecal microbiotas displaying more diversity than human fecal microbiotas. The nutrient requirements of each microbiota growing under batch and chemostat conditions were analyzed. The results showed that chicken cecal microbiotas required simple sugars and peptides to maintain balanced growth
in vitro
but that human fecal microbiotas preferred polysaccharides and proteins. Chicken microbiotas also produced higher concentrations of volatile fatty acids than did human microbiotas. Our data suggest that the availability of different fermentable substrates in the chicken cecum, which exist due to the unique anatomical structure of the cecum, may provide an environment favorable to the nourishment of microbiotas suited to the production of the higher-energy metabolites required by the bird. Therefore, gut structure, nutrition, immunity, and life-style all contribute to the selection of an exclusive bacterial community that produces types of metabolites beneficial to the host.
Ecophysiological Characterization of Ammonia-Oxidizing Archaea and Bacteria from Freshwater
Authors: French Elizabeth , Kozlowski Jessica A. , Mukherjee Maitreyee , Bullerjahn George , Bollmann Annette
Published: June 2012

Aerobic biological ammonia oxidation is carried out by two groups of microorganisms, ammonia-oxidizing bacteria (AOB) and the recently discovered ammonia-oxidizing archaea (AOA). Here we present a study using cultivation-based methods to investigate the differences in growth of three AOA cultures and one AOB culture enriched from freshwater environments. The strain in the enriched AOA culture belong to thaumarchaeal group I.1a, with the strain in one enrichment culture having the highest identity with “
Candidatus
Nitrosoarchaeum koreensis” and the strains in the other two representing a new genus of AOA. The AOB strain in the enrichment culture was also obtained from freshwater and had the highest identity to AOB from the
Nitrosomonas oligotropha
group (
Nitrosomonas
cluster 6a). We investigated the influence of ammonium, oxygen, pH, and light on the growth of AOA and AOB. The growth rates of the AOB increased with increasing ammonium concentrations, while the growth rates of the AOA decreased slightly. Increasing oxygen concentrations led to an increase in the growth rate of the AOB, while the growth rates of AOA were almost oxygen insensitive. Light exposure (white and blue wavelengths) inhibited the growth of AOA completely, and the AOA did not recover when transferred to the dark. AOB were also inhibited by blue light; however, growth recovered immediately after transfer to the dark. Our results show that the tested AOB have a competitive advantage over the tested AOA under most conditions investigated. Further experiments will elucidate the niches of AOA and AOB in more detail.
Association of Cry1Ac Toxin Resistance in Helicoverpa zea (Boddie) with Increased Alkaline Phosphatase Levels in the Midgut Lumen
Authors: Caccia Silvia , Moar William J. , Chandrashekhar Jayadevi , Oppert Cris , Anilkumar Konasale J. , Jurat-Fuentes Juan Luis , Ferré Juan
Published: June 2012

Resistance to
Bacillus thuringiensis
Cry1Ac toxin was characterized in a population of
Helicoverpa zea
larvae previously shown not to have an alteration in toxin binding as the primary resistance mechanism to this toxin. Cry1Ac-selected larvae (AR1) were resistant to protoxins and toxins of Cry1Ab, Cry1Ac, and the corresponding modified proteins lacking helix α-1 (Cry1AbMod and Cry1AcMod). When comparing brush border membrane vesicles (BBMVs) prepared from susceptible (LC) and AR1 larval midguts, there were only negligible differences in overall Cry1Ac toxin binding, though AR1 had 18% reversible binding, in contrast to LC, in which all binding was irreversible. However, no differences were detected in Cry1Ac-induced pore formation activity in BBMVs from both strains. Enzymatic activities of two putative Cry1Ac receptors (aminopeptidase N [APN] and alkaline phosphatase [ALP]) were significantly reduced (2-fold and 3-fold, respectively) in BBMVs from AR1 compared to LC larvae. These reductions corresponded to reduced protein levels in midgut luminal contents only in the case of ALP, with an almost 10-fold increase in specific ALP activity in midgut fluids from AR1 compared to LC larvae. Partially purified
H. zea
ALP bound Cry1Ac toxin in ligand blots and competed with Cry1Ac toxin for BBMV binding. Based on these results, we suggest the existence of at least one mechanism of resistance to Cry1A toxins in
H. zea
involving binding of Cry1Ac toxin to an ALP receptor in the larval midgut lumen of resistant larvae.
Cloning, Production, and Functional Expression of the Bacteriocin Enterocin A, Produced by Enterococcus faecium T136, by the Yeasts Pichia pastoris, Kluyveromyces lactis, Hansenula polymorpha, and Arxula adeninivorans
Authors: Borrero Juan , Kunze Gotthard , Jiménez Juan J. , Böer Erik , Gútiez Loreto , Herranz Carmen , Cintas Luis M. , Hernández Pablo E.
Published: June 2012

The bacteriocin enterocin A (EntA) produced by
Enterococcus faecium
T136 has been successfully cloned and produced by the yeasts
Pichia pastoris
X-33EA,
Kluyveromyces lactis
GG799EA,
Hansenula polymorpha
KL8-1EA, and
Arxula adeninivorans
G1212EA. Moreover,
P. pastoris
X-33EA and
K. lactis
GG799EA produced EntA in larger amounts and with higher antimicrobial and specific antimicrobial activities than the EntA produced by
E. faecium
T136.
Differences in Substrate Specificities of Five Bacterial Wax Ester Synthases
Authors: Barney Brett M. , Wahlen Bradley D. , Garner EmmaLee , Wei Jiashi , Seefeldt Lance C.
Published: June 2012

Wax esters are produced in certain bacteria as a potential carbon and energy storage compound. The final enzyme in the biosynthetic pathway responsible for wax ester production is the bifunctional wax ester synthase/acyl-coenzyme A (acyl-CoA):diacylglycerol acyltransferase (WS/DGAT), which utilizes a range of fatty alcohols and fatty acyl-CoAs to synthesize the corresponding wax ester. We report here the isolation and substrate range characterization for five WS/DGAT enzymes from four different bacteria:
Marinobacter aquaeolei
VT8,
Acinetobacter baylyi
,
Rhodococcus jostii
RHA1, and
Psychrobacter cryohalolentis
K5. The results from kinetic studies of isolated enzymes reveal a differential activity based on the order of substrate addition and reveal subtle differences between the substrate selectivity of the different enzymes. These
in vitro
results are compared to the wax ester and triacylglyceride product profiles obtained from each organism grown under neutral lipid accumulating conditions, providing potential insights into the role that the WS/DGAT enzyme plays in determining the final wax ester products that are produced under conditions of nutrient stress in each of these bacteria. Further, the analysis revealed that one enzyme in particular from
M. aquaeolei
VT8 showed the greatest potential for future study based on rapid purification and significantly higher activity than was found for the other isolated WS/DGAT enzymes. The results provide a framework to test prospective differences between these enzymes for potential biotechnological applications such as high-value petrochemicals and biofuel production.
Longitudinal Study of the Contamination of Air and of Soil Surfaces in the Vicinity of Pig Barns by Livestock-Associated Methicillin-Resistant Staphylococcus aureus
Authors: Schulz Jochen , Friese Anika , Klees Sylvia , Tenhagen Bernd A. , Fetsch Alexandra , Rösler Uwe , Hartung Jörg
Published: June 2012

During 1 year, samples were taken on 4 days, one sample in each season, from pigs, the floor, and the air inside pig barns and from the ambient air and soil at different distances outside six commercial livestock-associated methicillin-resistant
Staphylococcus aureus
(LA-MRSA)-positive pig barns in the north and east of Germany. LA-MRSA was isolated from animals, floor, and air samples in the barn, showing a range of airborne LA-MRSA between 6 and 3,619 CFU/m
3
(median, 151 CFU/m
3
). Downwind of the barns, LA-MRSA was detected in low concentrations (11 to 14 CFU/m
3
) at distances of 50 and 150 m; all upwind air samples were negative. In contrast, LA-MRSA was found on soil surfaces at distances of 50, 150, and 300 m downwind from all barns, but no statistical differences could be observed between the proportions of positive soil surface samples at the three different distances. Upwind of the barns, positive soil surface samples were found only sporadically. Significantly more positive LA-MRSA samples were found in summer than in the other seasons both in air and soil samples upwind and downwind of the pig barns.
spa
typing was used to confirm the identity of LA-MRSA types found inside and outside the barns. The results show that there is regular airborne LA-MRSA transmission and deposition, which are strongly influenced by wind direction and season, of up to at least 300 m around positive pig barns. The described boot sampling method seems suitable to characterize the contamination of the vicinity of LA-MRSA-positive pig barns by the airborne route.
Diurnal Infection Patterns and Impact of Microcystis Cyanophages in a Japanese Pond
Authors: Kimura Shigeko , Yoshida Takashi , Hosoda Naohiko , Honda Takashi , Kuno Sotaro , Kamiji Rikae , Hashimoto Ryoya , Sako Yoshihiko
Published: June 2012

Viruses play important roles in regulating the abundance, clonal diversity, and composition of their host populations. To assess their impact on the host populations, it is essential to understand the dynamics of virus infections in the natural environment. Cyanophages often carry host-like genes, including photosynthesis genes, which maintain host photosynthesis. This implies a diurnal pattern of cyanophage infection depending on photosynthesis. Here we investigated the infection pattern of
Microcystis
cyanophage by following the abundances of the Ma-LMM01-type phage tail sheath gene
g91
and its transcript in a natural population. The relative
g91
mRNA abundance within host cells showed a peak during the daylight hours and was lowest around midnight. The phage
g91
DNA copy numbers in host cell fractions, which are predicted to indicate phage replication, increased in the afternoon, followed by an increase in the free-phage fractions. In all fractions, at least 1 of 71
g91
genotypes was observed (in tested host cell, free-phage, and RNA fractions), indicating that the replication cycle of the cyanophage (i.e., injection, transcription, replication, and release of progeny phages) was occurring. Thus,
Microcystis
cyanophage infection occurs in a diel cycle, which may depend on the light cycle. Additionally, our data show that the abundance of mature cyanophage produced within host cells was 1 to 2 orders of magnitude greater than that of released phages, suggesting that phage production may be higher than previously reported.
Enhancement of the Structural Stability of Full-Length Clostridial Collagenase by Calcium Ions
Authors: Ohbayashi Naomi , Yamagata Noriko , Goto Masafumi , Watanabe Kimiko , Yamagata Youhei , Murayama Kazutaka
Published: June 2012

The clostridial collagenases G and H are multidomain proteins. For collagen digestion, the domain arrangement is likely to play an important role in collagen binding and hydrolysis. In this study, the full-length collagenase H protein from
Clostridium histolyticum
was expressed in
Escherichia coli
and purified. The N-terminal amino acid of the purified protein was Ala31. The expressed protein showed enzymatic activity against azocoll as a substrate. To investigate the role of Ca
2+
in providing structural stability to the full-length collagenase H, biophysical measurements were conducted using the recombinant protein. Size exclusion chromatography revealed that the Ca
2+
chelation by EGTA induced interdomain conformational changes. Dynamic light scattering measurements showed an increase in the percent polydispersity as the Ca
2+
was chelated, suggesting an increase in protein flexibility. In addition to these conformational changes, differential scanning fluorimetry measurements revealed that the thermostability was decreased by Ca
2+
chelation, in comparison with the thermal melting point (

T
m

). The melting point changed from 54 to 49°C by the Ca
2+
chelation, and it was restored to 54°C by the addition of excess Ca
2+
. These results indicated that the interdomain flexibility and the domain arrangement of full-length collagenase H are reversibly regulated by Ca
2+
.