bluuebunny/crossref_metadata_2025 huggingface dataset:
Rapid Fractionation of Natural Organic Matter in Water Using a Novel Solid‐Phase Extraction Technique
Authors: Ratpukdi Thunyalux , Rice James A. , Chilom Gabriela , Bezbaruah Achintya , Khan Eakalak
Published: October 2009

This paper introduces a novel natural organic matter (NOM) fractionation technique using solid‐phase extraction cartridges. The new technique requires only 6 hours of fractionation time, which is much faster than traditional fractionation techniques (24 hours). It uses three Bond Elute ENV cartridges (Varian, Inc., Lake Forest, California), one Strata X‐C cartridge (Phenomenex, Torrance, California), and one Strata X‐AW cartridge (Phenomenex) in series and was tested by using to fractionate NOM from Suwannee River, Georgia (SRNOM) and Red River, Minnesota (RRNOM). Hydrophobic acid was a major fraction and accounted for 66 to 70% and 36% of SRNOM and RRNOM, respectively. The NOM fractions obtained from the developed method were characterized using Fourier transformed infrared spectroscopy and 13C nuclear magnetic resonance. The acid fractions of SRNOM mainly consisted of carboxylic acids. An application of this new technique was demonstrated by using it to investigate the effectiveness of water treatment processes in removing different NOM fractions.
Thermophilic Sidestream Anaerobic Membrane Bioreactors: The Shear Rate Dilemma
Authors: Jeison D. , Telkamp P. , van Lier J.B.
Published: October 2009

Anaerobic biomass retention under thermophilic conditions has proven difficult. Membrane filtration can be used as alternative way to achieve high sludge concentrations. This research studied the feasibility of anaerobic membrane bioreactors (AnMBRs) under thermophilic conditions. A sidestream MBR was operated at crossflow velocities up to 1.5 m/s. For comparison, a thermophilic upflow sludge blanket reactor also was operated. Results confirmed that biomass retention may limit the performance of sludge bed reactors during long‐term operation. During MBR operation, cake formation was identified as the key factor limiting the applicable flux. Low levels of irreversible fouling were observed. Even though high shear can provide an increase in particle back‐transport, exposure of the sludge to a high shear stress produced a reduction of particle size, affecting the attainable flux. The concept of “shear rate dilemma” is introduced to describe this dual effect of shear during the operation of MBRs.
The Two-Semester Thesis Model: Emphasizing Research in Undergraduate Technical Communication Curricula
Authors: Ford Julie Dyke , Bracken Jennifer L. , Wilson Gregory D.
Published: October 2009

This article addresses previous arguments that call for increased emphasis on research in technical communication programs. Focusing on the value of scholarly-based research at the undergraduate level, we present New Mexico Tech's thesis model as an example of helping students develop familiarity with research skills and methods. This two-semester sequence serves as a capstone experience for students' writing, designing, editing, and presentation skills. It also involves members of our corporate advisory board and provides an opportunity to teach students to understand and apply research methods to unique projects, skills we argue will benefit students no matter what environments they enter upon graduation.
Tuberculous spondylitis in patients with end-stage renal disease undergoing chronic hemodialysis therapy — Report of two cases
Authors: Kostov Kosta , Yovchevski Plamen , Petrov Ivan
Published: October 2009

Tuberculous spondylitis is more common in patients with chronic renal failure who receive hemodialysis because of their abnormal T-cell-mediated immunity. It frequently poses both diagnostic and therapeutic challenges. We describe two cases of tuberculous spondylitis in patients undergoing chronic hemodialysis therapy. They are IFN-γ assay diagnosed (QuantiFERON-TB Gold) and conservatively treated. Our cases suggest that IFN-γ assays equip clinicians with more accurate tools for tuberculosis control. A combination of T-SPOT.TB testing and MRI assessment may be the accurate method to diagnose tuberculous spondylitis in patients with end-stage renal disease.
The Effect of Ovariectomy and Estrogen on Penetrating Brain Arterioles and Blood‐Brain Barrier Permeability
Authors: Cipolla Marilyn J. , Godfrey Julie A. , Wiegman Marchien J.
Published: October 2009

Objective: We investigated the effect of estrogen replacement on the structure and function of penetrating brain arterioles (PA) and blood‐brain barrier (BBB) permeability.

Materials and Methods: Female ovariectomized Sprague‐Dawley rats were replaced with estradiol (E2) and estriol (E3) (OVX + E;N=13) and compared to ovariectomized animals without replacement (OVX; N=14) and intact controls (CTL, proestrous; N=13). Passive and active diameters, percent tone, and passive distensibility of pressurized PA were compared. In addition, BBB permeability to Lucifer Yellow, a marker of transcellular transport, was compared in cerebral arteries.

Results: Ovariectomy increased myogenic tone in PA, compared to CTL, that was not ameliorated by estrogen treatment. Percent tone at 75 mmHg for CTL vs. OVX and OVX + E was 44±3% vs. 51±1% and 54±3% (P<0.01 vs. CTL for both). No differences were found in passive diameters or distensibility between the groups. BBB permeability increased 500% in OVX vs. CTL animals; however, estrogen replacement restored barrier properties: flux of Lucifer Yellow for CTL, OVX, and OVX + E was (ng/mL): 3.4±1.2, 20.2±5.3 (P<0.01 vs. CTL), and 6.15±1.2 (n.s.).

Conclusions: These results suggest that estrogen replacement may not be beneficial for small‐vessel disease in the brain, but may limit BBB disruption and edema under conditions that cause it.
A mathematical model of vasoreactivity in rat mesenteric arterioles: I. Myoendothelial communication
Authors: Kapela Adam , Bezerianos Anastasios , Tsoukias Nikolaos M.
Published: October 2009

To study the effect of myoendothelial communication on vascular reactivity, we integrated detailed mathematical models of Ca2+ dynamics and membrane electrophysiology in arteriolar smooth muscle (SMC) and endothelial (EC) cells. Cells are coupled through the exchange of Ca2+, Cl−, K+, and Na+ ions, inositol 1,4,5‐triphosphate (IP3), and the paracrine diffusion of nitric oxide (NO). EC stimulation reduces intracellular Ca2+ ([Ca2+ in the SMC by transmitting a hyperpolarizing current carried primarily by K+. The NO‐independent endothelium‐derived hyperpolarization was abolished in a synergistic‐like manner by inhibition of EC SKCa and IKCa channels. During NE stimulation, IP3diffusing from the SMC induces EC Ca2+ release, which, in turn, moderates SMC depolarization and [Ca2+]i elevation. On the contrary, SMC [Ca2+]i was not affected by EC‐derived IP3. Myoendothelial Ca2+ fluxes had no effect in either cell. The EC exerts a stabilizing effect on calcium‐induced calcium release‐dependent SMC Ca2+ oscillations by increasing the norepinephrine concentration window for oscillations. We conclude that a model based on independent data for subcellular components can capture major features of the integrated vessel behavior. This study provides a tissue‐specific approach for analyzing complex signaling mechanisms in the vasculature.
National Cancer Control Strategy - One Step Forward
Authors: Majed MA
Published: October 2009

DOI: 10.3329/bmj.v38i1.3578 Bangladesh Medical Journal 38(1) 2009 1-2
Determinants of Tobacco Use in a Selected Urban Area of Bangladesh
Authors: Uddin Gias , Rahman Md Mizanur , Hussain Syed Md Akram
Published: October 2009

Tobacco consumption is harmful to health, and is one of the main causes of death in worldwide. It is evident that the prevalence of tobacco consumption is raising in most of low and middle income countries. Considering this, a cross sectional study was conducted in a selected urban area of southern Bangladesh with a view to assessing the prevalence of tobacco consumption and factors affecting the use of tobacco use. Multistage cluster sampling technique was adopted to select the urban ward and the respondents were selected systematically. A total of 399 respondents were interviewed face to face using a semi-structured interview schedule. Analysis shows that 30% of the population of aged 18 years above were currently using tobacco of any form. The mean age of starting tobacco use was 18.8 years. The most frequent form of tobacco use was smoking cigarette followed by Zarda with betal quid. Multivariate analysis revealed that illiterate respondents were 3.3 times more tobacco users than their educated counterparts. It was also higher among the Muslims (OR=4.979; 95% CI=1.255-19.754). Tobacco use was also high among the labourer (OR=8.541; 95% CI=2.422-30.120) and businessmen (OR=7.727, 95% CI=2.501-23.875). However, no statistically significant association was found between current tobacco use and age, sex, housing condition and knowledge on tobacco use (p>0.05). The finding of this study suggests that as tobacco use is more prevalent among the poor and illiterate segment of the population, strong implementation of anti-tobacco legislation is warranted.   DOI: 10.3329/bmj.v38i2.3573 Bangladesh Medical Journal 38(2) 2009 48-52
Atypical Presentation of Vulval Tuberculosis
Authors: Akther Rabeya , Mohiuddin Md Golam , Afroj Hasina
Published: October 2009

A 25yrs old lactating women present with membranous lesion of the tongue, painful ulceration of mouth and vulva. The differential diagnosis of vulval ulcer includes various causes of acute vulval lesion usually associated with STD, malignancy and immunosuppressive disease. Later it is diagnosed as a case of vulval tuberculosis. This common lesion is often misdiagnosed, leading unnecessary investigations and treatment.   DOI: 10.3329/bmj.v38i2.3577 Bangladesh Medical Journal 38(2) 2009 65-67
A CMOS-Compatible, Low-Noise ISFET Based on High Efficiency Ion-Modulated Lateral-Bipolar Conduction
Authors: Chang Sheng-Ren , Chen Hsin
Published: October 2009

Ion-sensitive, field-effect transistors (ISFET) have been useful biosensors in many applications. However, the signal-to-noise ratio of the ISFET is limited by its intrinsic, low-frequency noise. This paper presents an ISFET capable of utilizing lateral-bipolar conduction to reduce low-frequency noise. With a particular layout design, the conduction efficiency is further enhanced. Moreover, the ISFET is compatible with the standard CMOS technology. All materials above the gate-oxide are removed by simple, die-level post-CMOS process, allowing ions to modulate the lateral-bipolar current directly. By varying the gate-to-bulk voltage, the operation mode of the ISFET is controlled effectively, so is the noise performance measured and compared. Finally, the biasing conditions preferable for different low-noise applications are identified. Under the identified biasing condition, the signal-to-noise ratio of the ISFET as a pH sensor is proved to be improved by more than five times.
Motivations, Commitment, and Intentions to Continue Volunteering for Sporting Events
Authors: Bang Hyejin , Won Doyeon , Kim Yongjae
Published: October 2009

Volunteers are an integral human resource of most sporting events organizations in producing successful events. To sustain a volunteer workforce, building a sense of motivation, commitment, and intention to continue volunteering is one of the most important tasks of event organizations
and managers. The purpose of the study is to examine the relationships between motivations and commitment as predictors of volunteers' intentions to continue to volunteer for future sporting events. For this purpose, 163 individuals (males = 70; females = 93) who volunteered at the 2005 Life
Time Fitness Triathlon participated in a Web-based survey. The results revealed that Interpersonal Contacts, Love of Sport, and Personal Growth as volunteer motivation factors had a significant influence on the volunteers' commitment to the sporting event. The volunteers' Commitment
and motivations, Community Involvement, and Extrinsic Rewards were found to be important variables in predicting intentions to continue to volunteer for future sporting events as well. This article provides a better understanding of volunteers' motivations and their relationships
with commitment and intentions for sporting event managers in using the information with effective volunteer retention strategies.
A Study of WLAN Campus in an Educational Establishment
Authors: Abdul-Hameed Taghareed , Hunaiti Ziad , Sedoyeka Eliamani
Published: October 2009

the main aim of campus network is to efficiently separate, share and access knowledge among its users. The big demand of such systems of distributed knowledge networks is to be able to handle advanced applications which are the end-user requirements. The main goal of this study is to assess the ability of WLAN campus to dealing with applications request of end users in education establishments and network achievement under different conditions of operation. The study has been conducted in two stages: the first stage was accomplished by conducting a survey, using the Student Village network at Anglia Ruskin University as a case study; the main aim was to determine end-use requirements, gather information about the nature applications running by users and get a view about the likely future applications. The second stage was achieved by conducting experiments to evaluate the WLAN campus network performance under various different scenarios: impact of handover from Access Point (AP) to another AP on end-user link performance, network performance in different usage time and network performance in different weather conditions.
Descendit ad [in] inferna: ‘A matter of no small moment in bringing about redemption’
Authors: Buitendag Johan
Published: October 2009

This article endorses Calvin’s conviction that the ‘descendit ad inferna’ of the Apostles’ Creed is part of the ‘summary of doctrine‘ and a matter of ‘no small moment in bringing about redemption‘ (Calvin 1960:Inst. II, xvi, 8). The reason for this role, however, is not Calvin’s metaphorical interpretation of the clause. Instead, the author tries to argue that a scientific theological approach will maintain the clause because of its transcendence of finitude and the proclamation of Christ’s victory. The whole of creation is delivered from sin. Proper hermeneutics will take the original socio–historical environment into account and make one suspicious about certain ecclesiastical biases. Spatial terms in the Creed should therefore not be demythologised, but rather be transformed in accordance with the insights of the contemporary physics of time and space.
Harmonicity of Holomorphic Maps Between Almost Hermitian Manifolds
Authors: Chinea Domingo
Published: October 2009

In this paper we study holomorphic maps between almost Hermitian manifolds. We obtain a new criterion for the harmonicity of such holomorphic maps, and we deduce some applications to horizontally conformal holomorphic submersions.
Right and Left Weak Approximation Properties in Banach Spaces
Authors: Choi Changsun , Kim Ju Myung , Lee Keun Young
Published: October 2009

New necessary and sufficient conditions are established for Banach spaces to have the approximation property; these conditions are easier to check than the known ones. A shorter proof of a result of Grothendieck is presented, and some properties of a weak version of the approximation property are addressed.
Small Zeros of Quadratic Forms Avoiding a Finite Number of Prescribed Hyperplanes
Authors: Dietmann Rainer
Published: October 2009

We prove a new upper bound for the smallest zero x of a quadratic form over a number field with the additional restriction that x does not lie in a finite number of m prescribed hyperplanes. Our bound is polynomial in the height of the quadratic form, with an exponent depending only on the number of variables but not on m.
Hartogs’ Theorem on Separate Holomorphicity for Projective Spaces
Authors: Gauthier P. M. , Zeron E. S.
Published: October 2009

If a mapping of several complex variables into projective space is holomorphic in each pair of variables, then it is globally holomorphic.
Matrix Valued Orthogonal Polynomials on the Unit Circle: Some Extensions of the Classical Theory
Authors: Miranian L.
Published: October 2009

In the work presented below the classical subject of orthogonal polynomials on the unit circle is discussed in the matrix setting. An explicit matrix representation of the matrix valued orthogonal polynomials in terms of the moments of the measure is presented. Classical recurrence relations are revisited using the matrix representation of the polynomials. The matrix expressions for the kernel polynomials and the Christoffel–Darboux formulas are presented for the first time.
On the Rational Points of the Curve f (X,Y)q = h(X)g(X,Y)
Authors: Poulakis Dimitrios
Published: October 2009

Let q = 2, 3 and f (X, Y), g(X, Y), h(X) be polynomials with integer coefficients. In this paper we deal with the curve f (X, Y)q = h(X)g(X,Y), and we show that under some favourable conditions it is possible to determine all of its rational points.
The Erdős–Rado Arrow for Singular Cardinals
Authors: Shelah Saharon
Published: October 2009

We prove in ZFC that if cf(λ) > ℵ0and 2cf(λ)< λ, then λ → (λ, ω + 1)2.
2-Clean Rings
Authors: Wang Z. , Chen J. L.
Published: October 2009

A ring R is said to be n-clean if every element can be written as a sum of an idempotent and n units. The class of these rings contains clean rings and n-good rings in which each element is a sum of n units. In this paper, we show that for any ring R, the endomorphism ring of a free R-module of rank at least 2 is 2-clean and that the ring B(R) of all ω × ω row and column-finite matrices over any ring R is 2-clean. Finally, the group ring RCn is considered where R is a local ring.
Extension of the Riemann ξ-Function's Logarithmic Derivative Positivity Region to Near the Critical Strip
Authors: Broughan Kevin A.
Published: October 2009

If K is a number field with nk = [k : ℚ], and ξk the symmetrized Dedekind zeta function of the field, the inequality

for t ≠ 0 is shown to be true for σ ≥ 1 + improving the result of Lagarias where the constant in the inequality was 9. In the case k = ℚ the inequality is extended to σ ≥ 1 for all t sufficiently large or small and to the region σ ≥ 1 + 1/(log t – 5) for all t ≠ 0. This answers positively a question posed by Lagarias.
Essential Surfaces in Graph Link Exteriors
Authors: Ikeda Toru
Published: October 2009

An irreducible graph manifold M contains an essential torus if it is not a special Seifert manifold. WhetherM contains a closed essential surface of negative Euler characteristic or not depends on the difference of Seifert fibrations from the two sides of a torus system which splits M into Seifert manifolds. However, it is not easy to characterize geometrically the class of irreducible graph manifolds which contain such surfaces. This article studies this problem in the case of graph link exteriors.
Amalgamations of Categories
Authors: MacDonald John , Scull Laura
Published: October 2009

We consider the pushout of embedding functors in Cat, the category of small categories. We show that if the embedding functors satisfy a 3-for-2 property, then the induced functors to the pushout category are also embeddings. The result follows from the connectedness of certain associated slice categories. The condition is motivated by a similar result for maps of semigroups. We show that our theorem can be applied to groupoids and to inclusions of full subcategories. We also give an example to show that the theorem does not hold when the property only holds for one of the inclusion functors, or when it is weakened to a one-sided condition.
Global Geometrical Coordinates on Falbel's Cross-Ratio Variety
Authors: Parker John R. , Platis Ioannis D.
Published: October 2009

Falbel has shown that four pairwise distinct points on the boundary of a complex hyperbolic 2-space are completely determined, up to conjugation in PU(2, 1), by three complex cross-ratios satisfying two real equations. We give global geometrical coordinates on the resulting variety.
Generic Quasi-Convergence for Essentially Strongly Order-Preserving Semiflows
Authors: Yi Taishan , Zou Xingfu
Published: October 2009

By employing the limit set dichotomy for essentially strongly order-preserving semiflows and the assumption that limit sets have infima and suprema in the state space, we prove a generic quasi-convergence principle implying the existence of an open and dense set of stable quasi-convergent points. We also apply this generic quasi-convergence principle to a model for biochemical feedback in protein synthesis and obtain some results about the model which are of theoretical and realistic significance.
Geometric “Floral” Configurations
Authors: Berman Leah Wrenn , Bokowski Jürgen , Grünbaum Branko , Pisanski Tomaž
Published: October 2009

With an increase in size, configurations of points and lines in the plane usually become complicated and hard to analyze. The “floral” configurations we are introducing here represent a new type that makes accessible and visually intelligible even configurations of considerable size. This is achieved by combining a large degree of symmetry with a hierarchical construction. Depending on the details of the interdependence of these aspects, there are several subtypes that are described and investigated.
Successive Minima and Radii
Authors: Henk Martin , Hernández Cifre María A.
Published: October 2009

In this note we present inequalities relating the successive minima of an o-symmetric convex body and the successive inner and outer radii of the body. These inequalities join known inequalities involving only either the successive minima or the successive radii.
Transversals with Residue in Moderately Overlapping T(k)-Families of Translates
Authors: Heppes Aladár
Published: October 2009

Let K denote an oval, a centrally symmetric compact convex domain with non-empty interior. A family of translates of K is said to have property T(k) if for every subset of at most k translates there exists a common line transversal intersecting all of them. The integer k is the stabbing level of the family. Two translates Ki = K + ci and Kj = K + cj are said to be σ-disjoint if σK + ci and σK + cj are disjoint. A recent Helly-type result claims that for every σ > 0 there exists an integer k(σ) such that if a family of σ-disjoint unit diameter discs has property T(k)|k ≥ k(σ), then there exists a straight line meeting all members of the family. In the first part of the paper we give the extension of this theorem to translates of an oval K. The asymptotic behavior of k(σ) for σ → 0 is considered as well.

Katchalski and Lewis proved the existence of a constant r such that for every pairwise disjoint family of translates of an oval K with property T(3) a straight line can be found meeting all but at most r members of the family. In the second part of the paper σ-disjoint families of translates of K are considered and the relation of σ and the residue r is investigated. The asymptotic behavior of r(σ) for σ → 0 is also discussed.
Shaken Rogers's Theorem for Homothetic Sections
Authors: Jerónimo-Castro J. , Montejano L. , Morales-Amaya E.
Published: October 2009

We shall prove the following shaken Rogers's theorem for homothetic sections: Let K and L be strictly convex bodies and suppose that for every plane H through the origin we can choose continuously sections of K and L, parallel to H, which are directly homothetic. Then K and L are directly homothetic.
On the Bezdek–Pach Conjecture for Centrally Symmetric Convex Bodies
Authors: Lángi Zsolt , Naszódi Márton
Published: October 2009

The Bezdek–Pach conjecture asserts that the maximum number of pairwise touching positive homothetic copies of a convex body in ℝd is 2d. Naszódi proved that the quantity in question is not larger than 2d+1. We present an improvement to this result by proving the upper bound 3 · 2d–1 for centrally symmetric bodies. Bezdek and Brass introduced the one-sided Hadwiger number of a convex body. We extend this definition, prove an upper bound on the resulting quantity, and show a connection with the problem of touching homothetic bodies.
Two Volume Product Inequalities and Their Applications
Authors: Stancu Alina
Published: October 2009

Let K ⊂ ℝn+1 be a convex body of class C2 with everywhere positive Gauss curvature. We show that there exists a positive number δ(K) such that for any δ ∈ (0, δ(K)) we have Vol(Kδ) · Vol((Kδ)*) ≥ Vol(K) · Vol(K*) ≥ Vol(Kδ) · Vol((Kδ)*), where Kδ, Kδ and K* stand for the convex floating body, the illumination body, and the polar of K, respectively. We derive a few consequences of these inequalities.
The Parabolic Littlewood–Paley Operator with Hardy Space Kernels
Authors: Chen Yanping , Ding Yong
Published: October 2009

In this paper, we give the Lp boundedness for a class of parabolic Littlewood–Paley g-function with its kernel function Ω is in the Hardy space H1(Sn–1).
A Note on Locally Nilpotent Derivations and Variables of k[X, Y, Z]
Authors: Daigle Daniel , Kaliman Shulim
Published: October 2009

We strengthen certain results concerning actions of (ℂ, +) on ℂ3 and embeddings of ℂ2 in ℂ3, and show that these results are in fact valid over any field of characteristic zero.
Computing Polynomials of the Ramanujan tn Class Invariants
Authors: Konstantinou Elisavet , Kontogeorgis Aristides
Published: October 2009

We compute the minimal polynomials of the Ramanujan values tn, where n ≡ 11 mod 24, using the Shimura reciprocity law. These polynomials can be used for defining the Hilbert class field of the imaginary quadratic field and have much smaller coefficients than the Hilbert polynomials.
Rhodium‐Catalysed Coupling of Allylic, Homoallylic, and Bishomoallylic Alcohols with Aldehydes and N‐Tosylimines: Insights into the Mechanism
Authors: Ahlsten Nanna , Martín‐Matute Belén
Published: October 2009

The isomerisation of alkenols followed by reaction with aldehydes or N‐tosylimines catalysed by rhodium complexes has been studied. The catalytically active rhodium complex is formed in situ from commercially available (cyclooctadiene)rhodium(I) chloride dimer [Rh(COD)Cl]2. The tandem process affords aldol and Mannich‐type products in excellent yields. The key to the success of the coupling reaction is the activation of the catalysts by reaction with postassium tert‐butoxide (t‐BuOK), which promotes a catalytic cycle via alkoxides rather than rhodium hydrides. This mechanism minimises the formation of unwanted by‐products. The mechanism has been studied by 1H NMR spectroscopy and deuterium labelling experiments.
Optimization of a multiphase sensor for detection of phosphonates in air
Authors: Monty Chelsea N. , Oh Ilwhan , Masel Richard I.
Published: October 2009

The objective of this article is to report the modeling and optimization of a new MEMS‐based phosphonate sensor that utilizes a porous membrane between a gas and a liquid stream to allow operation at low‐liquid and high‐gas flow rates. Previous work from our laboratory demonstrated that phosphonate molecules can be detected with such a device, but the sensitivity was insufficient for certain applications (e.g., detection of pesticides in foodstuffs). In this article, COMSOL simulations and design of experiments were used to optimize the device. We find that both the simulation and the experiment show that (i) the size of the pores in the membranes and (ii) the liquid channel height make the most difference to the sensor response. Also, by optimizing the geometry, the sensitivity of the device could be enhanced. The optimized device can detect 109 molecules with good signal to noise. © 2009 American Institute of Chemical Engineers AIChE J, 2010
Improved extraction of vanadium from a Chinese vanadium‐bearing stone coal using a modified roast‐leach process
Authors: Chen Tiejun , Zhang Yimin , Song Shaoxian
Published: October 2009

Vanadium is a rare metal mainly used in the steel industry. Vanadium‐bearing stone coal is an important source of vanadium in China. The common process used to extract vanadium from the stone coals is roast‐leach, which has the disadvantages of low vanadium recovery and significant pollution. This work presents a modified roast‐leach process in order to improve the efficiency of the extraction. The modifications include a two‐step leaching process: first water leach, followed by an acid leach of the water‐leaching residue in a dilute HCl solution. In addition, the precipitate was recycled from the acid‐leaching solution to the oxidation roast for use as a roasting agent, and low dosages of sodium salts (Na2CO3 and Na2SO4) were included in the oxidation roast to reduce the volume of HCl and Cl2 exhaust gases and environmental pollution. The study was performed on a typical vanadium‐bearing stone coal from the Xiushui mine in Jiangxi province, China. The results show that the modified process achieved a vanadium recovery of 85% from the stone coal, much higher than that from a one‐step leach process (water leach or acid leach alone). Also, it has been found that optimum values of the roast temperature and time in the preroast (750 °C and 30 min) and oxidation roast (780 °C and 90 min) were required in order to obtain the maximum vanadium recovery from stone coal. It is shown that the modified roast‐leach process is an economic and effective process for the recovery of vanadium from stone coals. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd.
A validated model of GAG deposition, cell distribution, and growth of tissue engineered cartilage cultured in a rotating bioreactor
Authors: Nikolaev N.I. , Obradovic B. , Versteeg H.K. , Lemon G. , Williams D.J.
Published: October 2009

In this work a new phenomenological model of growth of cartilage tissue cultured in a rotating bioreactor is developed. It represents an advancement of a previously derived model of deposition of glycosaminoglycan (GAG) in engineered cartilage by (i) introduction of physiological mechanisms of proteoglycan accumulation in the extracellular matrix (ECM) as well as by correlating (ii) local cell densities and (iii) tissue growth to the ECM composition. In particular, previously established predictions and correlations of local oxygen concentrations and GAG synthesis rates are extended to distinguish cell secreted proteoglycan monomers free to diffuse in cell surroundings and outside from the engineered construct, from large aggrecan molecules, which are constrained within the ECM and practically immovable. The model includes kinetics of aggregation, that is, transformation of mobile GAG species into immobile aggregates as well as maintenance of the normal ECM composition after the physiological GAG concentration is reached by incorporation of a product inhibition term. The model also includes mechanisms of the temporal evolution of cell density distributions and tissue growth under in vitro conditions. After a short initial proliferation phase the total cell number in the construct remains constant, but the local cell distribution is leveled out by GAG accumulation and repulsion due to negative molecular charges. Furthermore, strong repulsive forces result in expansion of the local tissue elements observed macroscopically as tissue growth (i.e., construct enlargement). The model is validated by comparison with experimental data of (i) GAG distribution and leakage, (ii) spatial‐temporal distributions of cells, and (iii) tissue growth reported in previous works. Validation of the model predictive capability—against a selection of measured data that were not used to construct the model—suggests that the model successfully describes the interplay of several simultaneous processes carried out during in vitro cartilage tissue regeneration and indicates that this approach could also be attractive for application in other tissue engineering systems. Biotechnol. Bioeng. 2010. 105: 842–853. © 2009 Wiley Periodicals, Inc.
Systematic engineering of phytochelatin synthesis and arsenic transport for enhanced arsenic accumulation in E. coli
Authors: Singh Shailendra , Kang Seung Hyun , Lee Wonkyu , Mulchandani Ashok , Chen Wilfred
Published: October 2009

Phytochelatin (PC) is a naturally occurring peptide with high affinity towards arsenic (As). In this article, we demonstrated the systematic engineering of PC‐producing E. coli for As accumulation by addressing different bottlenecks in PC synthesis as well as As transport. Phytochelatin synthase from Schizosaccharomyces pombe (SpPCS) was expressed in E. coli resulting in 18 times higher As accumulation. PC production was further increased by co‐expressing a feedback desensitized γ‐glutamylcysteine synthetase (GshI*), resulting in 30‐fold higher PC levels and additional 2‐fold higher As accumulation. The significantly increased PC levels were exploited further by co‐expressing an arsenic transporter GlpF, leading to an additional 1.5‐fold higher As accumulation. These engineering steps were finally combined in an arsenic efflux deletion E. coli strain to achieve an arsenic accumulation level of 16.8 µmol/g DCW, a 80‐fold improvement when compared to a control strain not producing phytochelatins. Biotechnol. Bioeng. 2010. 105: 780–785. © 2009 Wiley Periodicals, Inc.
Sentinel lymph node biopsy in breast cancer guided by indocyanine green fluorescence
Authors: Murawa D , Hirche C , Dresel S , Hünerbein M
Published: October 2009

Background

Sentinel lymph node (SLN) biopsy with radioisotope and blue dye has been used successfully for axillary staging in breast cancer. This study evaluated the feasibility of fluorescence detection of SLNs with indocyanine green (ICG) for lymphatic mapping and SLN biopsy.

Methods

Thirty women with breast cancer had a periareolar injection of ICG for fluorescence detection of SLN using a near-infrared camera. Twenty also received 99mTc-labelled sulphur radiocolloid for SLN scintigraphy. All patients underwent axillary lymph node dissection. Detection rate and sensitivity of both methods were the study endpoints.

Results

Visualization of lymphatic vessels by fluorescence detection depended on the dose of ICG. ICG imaging identified SLNs in 29 of 30 women (detection rate 97 per cent). Nineteen of 21 patients had metastatic SLN involvement (sensitivity 90 per cent) with false-negative results in two. Among the 20 patients who had both methods, ICG fluorescence and radiocolloid identified SLNs in 20 and 17 patients respectively. Metastatic lymph nodes were diagnosed in 12 and ten of 13 patients (sensitivity 92 and 77 per cent). False-negative rates were 8 and 23 per cent respectively.

Conclusion

ICG fluorescence allowed transcutaneous imaging of lymphatic vessels and SLN detection, thus combining the advantages of radioisotope and blue dye methods.
Vector fragmentation: Characterizing vector integrity in transfected clones by Southern blotting
Authors: Ng Say Kong , Lin Wenyu , Sachdeva Rohit , Wang Daniel I.C. , Yap Miranda G.S.
Published: October 2009

The Chinese Hamster Ovary production cell line development process using methotrexate (MTX) amplification is well studied and commonly used for biopharmaceutical processes. However, successful MTX amplification varies from clone to clone and suggested reasons include vector fragmentation during the transfection process and genomic rearrangement of the Chinese Hamster Ovary chromosomes. Here, we elucidated the vector integration patterns of 40 transfected single‐cell clones by Southern blotting and showed that vector fragmentation occurs at a significant level in our experiment. This concurs with MTX amplification studies implying that single‐cell cloning is necessary to ensure a successful amplification process. Truncations at the ends of the integrated vectors were also observed, whereas gross DNA insertions were not detected in our data. This suggests that end deletions are common, whereas insertion events are rare in animal cells. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010
Growth inhibition of dinoflagellate algae in shake flasks: Not due to shear this time!
Authors: Hu Weiwei , Gladue Ray , Hansen Jon , Wojnar Crystal , Chalmers Jeffrey J.
Published: October 2009

Large scale algae cultures present interesting challenges in that they exhibit characteristics of typical bacterial and animal cell cultures. One current commercial food additive, docosahexaenoic acid (DHA), is produced using the dinoflagellate algae, Crypthecodinium cohnii. Like animal cell culture, the perceived sensitivity of algae culture to hydrodynamic forces has potentially limited the agitation and aeration applied to these systems. However, the high density cultivation of C. cohnii required for an economically feasible process inevitably results in high oxygen demand. In this study, we demonstrated what first appeared to be a problem with shear sensitivity in shake flasks is most probably a mass transfer limitation. We subsequently demonstrated the limit of chronic and rapid energy dissipation rate, EDR, that C. cohnii cells can experience. This limit was determined using a microfluidic device connected in a recirculation loop to a stirred tank bioreactor, which has been previously used to repeatedly expose animal cells to high levels of EDR. Inhibition of cell growth was observed when C. cohnii cells were subjected to an EDR of 5.9 × 106 W/m3 with an average frequency of 0.2/min or more. This level of EDR is sufficiently high that C. cohnii can withstand typically encountered hydrodynamic forces in bioprocesses. This result suggests that at least one dinoflagellate algae, C. cohnii, is quite robust with respect to hydrodynamic forces and the scale‐up of process using this type of algae should be more concerned with providing sufficient gas transfer given the relatively high oxygen demand. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010
Synthesis, Inhibition Potency, Binding Mode, and Antiprotozoal Activities of Fluorescent Inhibitors of Trypanothione Reductase Based on Mepacrine‐Conjugated Diaryl Sulfide Scaffolds
Authors: Eberle Christian , Burkhard Johannes A. , Stump Bernhard , Kaiser Marcel , Brun Reto , Krauth‐Siegel R. Luise , Diederich François
Published: October 2009

Trypanothione reductase (TR) is a flavoenzyme unique to trypanosomatid parasites and a target for lead discovery programs. Various inhibitor scaffolds have emerged in the past, exhibiting moderate affinity for the parasite enzyme. Herein we show that the combination of two structural motifs of known TR inhibitors — diaryl sulfides and mepacrine — enables the simultaneous addressing of two hydrophobic patches in the active site. The binding efficacy of these conjugates is enhanced over that of the respective parent inhibitors. They show Kic values for the parasite enzyme down to 0.9±0.1 μm and exhibit high selectivity for TR over human glutathione reductase (GR). Despite their considerable molecular mass and in some cases permanent positive charges, in vitro studies revealed IC50 values in the low micromolar to sub‐micromolar range against Trypanosoma brucei rhodesiense and Trypanosoma cruzi, as well as the malaria parasite Plasmodium falciparum, which lack trypanothione metabolism. The inhibitors exhibit strong fluorescence due to their aminoacridine moiety. This feature allows visualization of the drugs in the parasite where high accumulation was observed by fluorescence microscopy even after short exposure times.
Evaluation of a dry format reagent alternative for CD4 T‐cell enumeration for the FACSCount system: A report on a Moroccan–Canadian study
Authors: Bergeron Michèle , Ding Tao , Elharti Elmir , Oumzil Hicham , Soucy Nadia , Harmouche Hicham , Chaouch Saad , Aouad Rajae EL , Chabot Christian , Mandy Francis
Published: October 2009

Background:

Efforts to improve alternative CD4 T‐cell counting methods are critical to accelerate the implementation of HIV antiretroviral therapy in resources limited regions. Substituting liquid format reagents to eliminate cold‐chain transportation and refrigerated storage with dry format reagents contributes to higher efficiency supply management solution especially for laboratories at remote locations. ReaMetrix has developed dry format reagent kits compatible with the FACSCount system, a dedicated flow cytometer for T‐cell subset enumeration widely used in resource limited settings. A dual site collaborative study was designed to compare T‐cell subsets using both the new dry format ReaMetrix reagent and the original BD Biosciences liquid reagents.

Method:

A total of 167 HIV positive samples prepared with Rea T Count (ReaMetrix) and FACSCount (BD Biosciences) reagents were analyzed using FACSCount Systems. To compare both methods, Bland‐Altman, Pollock, Scott % similarity and correlation coefficient statistical analysis was applied. Immuno‐Trol served as an assay processing control and quality indicator of interlaboratory and intralaboratory variation.

Results:

The mean bias and limits of agreement for CD4 T‐cell measurements between Rea T Count and FACSCount reagents were −16 cells/μl (−4.6%) and −74 to +43, respectively. The correlation obtained was 0.988 with a similarity of 97.9%. Between laboratory variation data was very good with %CV below 10%.

Conclusion:

The introduction of dry reagents permits the elimination of cold‐chain transportation and the on‐site refrigerated storage without compromise to assay quality. The substitution of dry reagents facilitates easier supply management practice that will assure wider access to quality HIV treatment. © 2009 Clinical Cytometry Society
Synthesis, X‐ray Crystal Structures, DNA Binding and Nuclease Activities of Two Novel 1,2,4‐Triazole‐Based CuII Complexes
Authors: Li Dong‐Dong , Tian Jin‐Lei , Gu Wen , Liu Xin , Yan Shi‐Ping
Published: October 2009

Two novel 1,2,4‐triazole‐based copper(II) complexes have been synthesized and structurally characterized by X‐ray crystallography: [Cu2LCl3]·0.5[CuCl4]·EtOH (1) and [Cu2LBr3]·Br·H2O (2) (L = 3,5‐bis{[bis(2‐methoxyethyl)amino]methyl}‐4H‐1,2,4‐triazol‐4‐amine). Single‐crystal diffraction reveals that the two Cu atoms have a distorted octahedral geometry for 2, but one Cu atom is in a distorted square‐pyramidal environment and the other one is in a distorted octahedral environment for 1 because of the different bridged halogen atoms. The interactions of the two complexes with calf thymus DNA (CT‐DNA) have been investigated by UV absorption, fluorescence spectroscopy, circular dichroism spectroscopy, viscosity measurements and cyclic voltammetry. The apparent binding constant (Kapp) values for complexes 1 and 2 are 2.98 × 106 and 4.05 × 106 M–1. Furthermore, both the compounds display efficient oxidative cleavage of supercoiled DNA in the presence of external agents. The rate constants for the conversions of supercoiled to nicked DNA are 4.38 × 10–4 s–1 (for 1) and 5.26 × 10–4 s–1 (for 2). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2010)
Asymmetric Synthesis of ES‐285, an Anticancer Agent Isolated from Marine Sources
Authors: Allepuz Ana C. , Badorrey Ramón , Díaz‐de‐Villegas María D. , Gálvez José A.
Published: October 2009

The asymmetric synthesis of (2S,3R)‐2‐amino‐3‐octanedecanol hydrochloride (ES‐285·HCl) was achieved in eight steps in ca. 38 % overall yield from the N‐benzylimine‐derived from (R)‐2,3‐O‐isopropylidene glyceraldehyde, which is easily available on gram scale from the inexpensive precursor D‐mannitol. Highly diastereoselective addition of methylmagnesium bromide to the N‐benzylimine was the key step to create the vic‐amino alcohol moiety with the appropriate configuration. Regioselective ring opening of an intermediate aminoepoxide enabled the introduction of the long hydrocarbon chain at C4.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Synthesis of Thioesters by Simultaneous Activation of Carboxylic Acids and Alcohols Using PPh3/NBS with Benzyltriethylammonium Tetrathiomolybdate as the Sulfur Transfer Reagent
Authors: Gopinath Purushothaman , Vidyarini Ravindran Sasitha , Chandrasekaran Srinivasan
Published: October 2009

A new and simple route for the synthesis of thioesters starting from carboxylic acids and alcohols is reported by using tetrathiomolybdate as the key sulfur transfer reagent. Triphenylphosphane and N‐bromosuccinimide were used for the activation of the carboxylic acid and alcohol in the same pot followed by the transfer of sulfur from tetrathiomolybdate. Thioesters were obtained in good to moderate yields. Primary alcohols show excellent reactivity and gave good yields of the corresponding thioesters, whereas secondary alcohols gave moderate yields and tertiary alcohols were very less reactive and gave poor yields of the corresponding thioesters.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)
Drei neue fossile Hölzer der Morphogattung Primoginkgoxylon gen. nov. aus der Trias von Kenia
Authors: Süss Herbert , Rößler Ronny , Boppré Michael , Fischer Ottmar W.
Published: October 2009

Drei permineralisierte Gymnospermenhölzer aus der Oberen Trias der Mazeras‐Formation (Duruma‐Gruppe, Mombasa‐Becken) werden beschrieben und aufgrund ihrer ginkgoalen Holzstruktur der neu errichteten Morphogattung Primoginkgoxylon gen. nov. zugeordnet (P. crystallophorum, P. muthamii, P. shimbaense). Die Kieselhölzer sind dreidimensional anatomisch erhalten und stammen aus dem fluviatil‐deltaischen Mazeras‐Sandstein, aufgeschlossen im Tal des Manolo River im Mwaluganje Community Elephant Sanctuary/Shimba‐Hills, im Südosten Kenias. Der Fundort wurde bisher nicht systematisch untersucht, erscheint jedoch sehr reich an Fossilien und verdient umfangreichere Untersuchungen wie in den Schlussbemerkungen erläutert wird. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Leaf architecture of Rhus s.str. (Anacardiaceae)
Authors: Andrés‐Hernández A. R. , Terrazas Teresa
Published: October 2009

A comprehensive leaf architecture study of 31 species of Rhus s.str. was conducted to describe and identify characters of potential value for assessing infrageneric relationships. The first detailed leaf descriptions for Rhus subgenera are provided and show that cleared leaves revealed craspedodromous, eucamptodromous, and cladodromous venation types in the species studied. There was a diversity of terminal idioblasts associated with free simple or branched veinlets, and a unique combination of leaf organization, venation type, terminal idioblasts, and crystals allowed identification of subgenera and sections. Within the genus, species with toothed deciduous compound leaves exhibit a tendency to mostly craspedodromous venation with weakly sclerified tertiary veins and poorly developed terminal idioblasts; species with simple or compound evergreen leaves show mostly eucamptodromous and cladodromous venation with sclerified bundle sheath cells towards fifth‐order veins and well‐developed terminal idioblasts. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)