bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of (3-hydroxy-2-phosphonylmethoxypropyl) derivatives of heterocyclic bases
Authors: Holý Antonín , Rosenberg Ivan , Dvořáková Hana
Published: May 2010

Analogs of the antiviral 9-(S)-(3-hydroxy-2-phosphonylmethoxypropyl)adenine (HPMPA, I), containing modified heterocyclic base, were prepared from racemic or (S)-N-(2,3-dihydroxypropyl) derivatives II. Compounds II are heated with chloromethylphosphonyl dichloride (XVII), the formed chloromethylphosphonylester chlorides of compounds II react with water to give a mixture of 2'- and 3'-chloromethylphosphonyl derivatives XVIII and XIX, respectively, which on isomerization by boiling with water in the arising acidic medium affords predominantly the 3'-isomer XIX. Treatment of this isomeric mixture with aqueous sodium hydroxide yields a mixture of 2'-O-phosphonylmethyl ethers (predominating, XXI) and 3'-O-phosphonylmethyl ethers of compounds II (XX). This approach has been applied to the synthesis of isomeric mixtures in the racemic as well as in the (S)-series derived from C-2, C-8 and N-6 substituted derivatives of adenine, from hypoxanthine and additional 6-substituted derivatives of purine, from guanine, 3-deazaadenine and other modified purine bases, from uracil, cytosine, their 5-methyl derivatives and 5-fluorouracil. Regioselective synthesis of compounds XXI was performed for biologically active derivatives (derivative of 2-aminoadenine (XXIe), guanine (XXIn), 3-deazaadenine (XXIp) and cytosine (XXIt)) as well as some other compounds (derivative of hypoxanthine (XXIj), uracil (XXIr), thymine (XXIs) and 5-methylcytosine (XXIu)): the former were obtained either from 3'-O-chloromethylphosphonyl derivatives XIX, isolated from the above-mentioned mixtures by ion-exchanger chromatography or HPLC, or by regioselective substitution, whereas the latter compounds were prepared by deamination (compound XXIj from adenine derivative I or the uracil and thymine derivatives XXIr and XXIu from the cytosine derivatives XXIt and XXIu). N-(S)-(3-Hydroxy-2-benzoyloxypropyl) derivative of N4-benzoylcytosine (XXIX) and N2-benzoylguanine (XXIV), obtained from compounds IIn and IIt by successive N-benzoylation, reaction with dimethoxytrityl chloride, benzoylation and mild acid treatment, were subjected to reaction with the chloride XVII and subsequent neutral and alkaline hydrolysis (compound XXIV), or to reaction with sodium methoxide followed by treatment with bromotrimethylsilane (compound XXIX), being thus converted into 1-(S)-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine (XXIt, HPMPC) and 9-(S)-(3-hydroxy-2-phosphonylmethoxypropyl)guanine (XXIn, HPMPG), respectively. The starting compounds (S)-II were synthesized from sodium salt of the corresponding heterocyclic base by reaction with 1-O-p-toluenesulfonyl-2,3-O-isopropylidene-(R)-glycerol (IIIa) (the (RS)-derivatives by reaction with 4-chloromethyl-2,2-dimethyl-1,3-dioxolane (IIIb)), followed by acid hydrolysis.
Synthesis, molecular conformation and biological activity of 6-amino-5-azacytidine
Authors: Pískala Alois , Hanna Naeem B. , Zajíček Jaroslav , Čihák Alois
Published: May 2010

Reaction of N-ethoxycarbonylguanidine III with 2,3,5-tri-O-benzoyl-β-D-ribosyl isocyanate (II) afforded N-ethoxycarbonylamidinourea IV, which was cyclized by bis(trimethylsilyl)acetamide to the 6-ethoxy derivative VII. Ammono- and methanolysis of intermediate VII yielded 6-amino and 6-methoxy derivatives of 5-azacytidine I and VIII, respectively. Reaction of amidinourea IV with a mixture of chlorotrimethylsilane and triethylamine gave the blocked nucleoside V which was also formed by dealkylation of 6-ethoxy derivative VII with chlorotrimethylsilane or oxidation of tribenzoyl-5-azacytidine IX with hydrogen peroxide in acetic acid. Methanolysis of blocked nucleoside V gave ribosylammelide (VI). The measurement of 1H NMR spectra of 6-amino-5-azacytidine (I) revealed a marked preference of g+ (80%) rotamer around C(5')-C(4') bond, a predominance of S conformation of the ribose ring (Keq 2.12) and a preference of anti conformation around the C-N glycosyl bond. These data indicate a conformational resemblance of 6-amino-5-azacytidine (I) to purine nucleosides. 6-Amino-5-azacytidine (I) inhibits the growth of bacteria E. coli while 6-methoxy and 6-oxo derivatives VIII and VI, respectively, are bacteriostatically inactive. 6-Amino-5-azacytidine (I) had an ID50 of 33.9 μM against CCRF-CEM cells and inhibited the growth of WI-L2 cells by 39% at 100 μM but did not inhibit L1210 and LoVo/L cells at ⪬ 100μM concentration.
Different rates of formation of secondary and tertiary structure during renaturation of urea-denatured human serum albumin
Authors: Chmelík Josef
Published: May 2010

A comparison of the results of our polarimetric measurements with the polarographic experiments reported earlier shows that the restoration of the secondary structure during the renaturation of human serum albumin is a process which is faster than the formation of the tertiary structure. These results, which are in agreement with the data on the kinetic control of protein folding, are discussed from the viewpoint of the importance of the individual types of interactions which take place during the formation and stabilization of three-dimensional protein structures. We have been able to demonstrate the great importance of electrostatic and hydrophobic interactions which together with the disulfide bonds are essential for the reversibility of the denaturation phenomena. The discussion also shows the essential role which evolution processes play in the selection of the mode of protein folding.
Forbidden transitions in molecular vibrational-rotational spectroscopy
Authors: Papoušek Dušan
Published: May 2010

A review is given of the forbidden ( more precisely: perturbation allowed) transistions between molecular vibrational-rotational states including transistions which are induced by the electric dipole and quadrupole moments and the magnetic dipole moment. The basic theory of these transistions is outlined starting with the overall symmetry selection rules, followed by the discussion of the spin statistics isomers, approximate selection rules for the usual vibrational-rotational transistions, and forbidden transistions induced by the electric quadrupole and magnetic dipole moments. Forbidden transistions due to the vibrationally and rotationally induced electric dipole moments are the discussed in detail for symmetric top and spherical top molecules with the emphasis on the physical nature of the various phenomena leading to these transistions. A summary is also given of the most important experimental work on the forbidden transistions in diatomic molecules and polar as well as nonpolar polyatomics.
Kinetic control and adsorption in the voltammetry of glyoxylate
Authors: Eggins Brian R. , McMullan E. Anne
Published: May 2010

Linear sweep voltammetry of glyoxylate on a stationary mercury electrode showed strong adsorption effects in addition to kinetic control because of the hydration of the aldehyde groups. The methods of Shain were used to minimise the adsorption and to determine the kinetic function at pH 9.0. The dehydration rate constant was found to be 1.14 ± 0.03 s-1.
Depression of freezing temperature of water and water solutions in porous materials
Authors: Schneider Petr , Rathouský Jiří
Published: May 2010

In porous materials filled with water or water solutions of inorganic salts, water freezes at lower temperatures than under normal conditions; the reason is the decrease of water vapor tension above the convex meniscus of liquid in pores. The freezing point depression is not very significant in pores with radii from 0.05 μm to 10 μm (about 0.01-2.5 K). Only in smaller pores, especially when filled with inorganic salt solutions, this depression is important.
Additivity of molar metachors of chlorides in aqueous solutions
Authors: Čeleda Jiří , Žilková Jana
Published: May 2010

For the molar metachor, a quantity expressing the electrostatic contribution from free (nonassociated and noncomplexed) ions to the surface tension of aqueous solutions of electrolytes, its additivity was verified for completely dissociating chlorides of univalent and divalent metals at concentrations up to 5 mol dm-3. Owing to this property, the degree of dissociation could be estimated for associating components of solutions containing also completely dissociated electrolytes. Measurements revealed that NaCl, LiCl, MgCl2 and CaCl2 in mixed solutions are completely dissociated whereas ZnCl2, CdCl2 and UO2Cl2 at molar ratios NaCl:MeCl = 2:1 and higher ( at cCl- = 5 mol dm-3) are completely transformed into electroneutral and anionic chloro complexes, the latter forming ion pairs and triplets with Na+ ions.
Transfer of knowledge in chemical equipment reliability
Authors: Babinec František , Dohnal Mirko
Published: May 2010

The problem of transformation of data on the reliability of chemical equipment obtained in particular conditions to other equipment in other conditions is treated. A fuzzy clustering algorithm is defined for this problem. The method is illustrated on a case study.
The supercooling ability of calcium nitrate solutions in ethylene glycol
Authors: Sláma Ivo , Malá Jarmila
Published: May 2010

The dependence of the induction period of crystallization on the supercooling was determined for the Ca(NO3)2-ethylene glycol system at mole fractions of the former from 0 to 0.049, and treated in terms of the TTT (Time-Temperature-Transformation) diagram. Addition of Ca(NO3)2 to ethylene glycol brings about a substantial increase in the critical induction period of crystallization. The thermal stability of glasses is discussed in terms of the shape and position of the TTT curves.
Utilization of 1,6-anhydrohexoses for the preparation of some aliphatic adenosine analogs
Authors: Krečmerová Marcela , Černý Miloslav , Buděšínský Miloš , Holý Antonín
Published: May 2010

Reaction of sodium salt of adenine with 1,6:3,4-dianhydro-2-O-p-toluenesulfonyl-β-D-galactopyranose (I) afforded 4-(adenin-9-yl)-1,6:2,3-dianhydro-4-deoxy-β-D-mannopyranose (II) and 2,4-bis(adenin-9-yl)-1,6-anhydro-2,4-dideoxy-β-D-glucopyranose (IV). Compound II was converted into 4-(adenin-9-yl)-1,6-anhydro-4-deoxy-β-D-glucopyranose (VI). Cleavage of the 1,6-anhydro bond in this compound with hot concentrated hydrochloric acid led to 4-(adenin-9-yl)-4-deoxy-D-glucose (VIII) which was reduced with sodium borohydride to give 4-(adenin-9-yl)-4-deoxy-D-glucitol (IX). Epoxide II was reduced with lithium aluminium hydride and the obtained 4-(adenin-9-yl)-1,6-anhydro-2,4-dideoxy-β-D-arabinohexopyranose (VII) on treatment with dilute hydrochloric acid and subsequent reduction with sodium borohydride gave 4-(adenin-9-yl)-2,4-dideoxy-D-arabino-hexitol (XI).
Glycosylation of steroids with silver silicate and 2-deoxy-2-fluoro-α-D-glucopyranosyl bromide triacetate
Authors: Černý Ivan , Novotný Petr , Drašar Pavel , Havel Miroslav , Pacák Josef
Published: May 2010

Glycosylation with the title glycosyl bromide I in 1,2-dichloroethane in the presence of silver silicate and a molecular sieves afforded mixtures of 3,4,6-tri-O-acetyl-2-deoxy-2-fluoro-α- and β-D-glucopyranosides (V-X), derived from ethyl (20E)-3β-hydroxy-24-nor-5,20(22)-choladien-23-oate (II), (20E)-3β-hydroxy-5β-pregn-20-ene-21-carboxylate (III) and 3β, 14-dihydroxy-5β, 14β-card-20(22)-enolide (IV, digitoxigenin), in which the β-anomers predominated. Separation and deacetylation furnished the corresponding 2-deoxy-2-fluoroglucosides XI-XVI.
New analogs of arginine-vasopressin containing β-homo-L-amino acid residues
Authors: Bankowski Krysztof , Misicka Alexandra , Barth Tomislav , Slaninová Jiřina
Published: May 2010

Four new analogs of arginine vasopressin containing β-homo-L-amino acid residue were synthesized by the solid-phase method. The introduced modifications yielded the following peptides:[β-homo Phe3]AVP (I), [β-homoPro7]AVP (II), [Cpp1, Tyr(Me)2, β-homoPhe3]AVP (III), and[Cpp1,Tyr(Me)2, β-homoPro7]AVP (IV). Agonistic properties of I and II, as well as antagonistic properties of III and IV were decreased, more pronouncedly with analogs substituted in the position 3.
Vapour-liquid equilibrium in the ternary system cyclohexane-acetic acid-propionic acid
Authors: Malijevská Ivona , Maštalková Alena , Sýsová Marie
Published: May 2010

Isobaric equilibrium data (P = 101.3 kPa) for the system cyclohexane-acetic acid-propionic acid have been measured by two different analytical techniques. Activity coefficients calculated by simultaneous solving of equations for the chemical and phase equilibria were subjected to a consistency test based on inaccuracies determined from the error propagation law, and were correlated by Wilson’s equation. The activity coefficients measured were compared with those calculated from binary vapour-liquid equilibrium data and with values predicted by the UNIFAC method.
Vapour-liquid equilibrium in the binary systems formed by ethylene glycol, diethylene glycol, and N-methylpyrrolidone
Authors: Surový Július , Graczová Elena , Ovečková Jana
Published: May 2010

Vapour-liquid equilibrium data are given for the binary systems ethylene glycol (EG)-N-methylpyrrolidone (NMP), ethylene glycol-diethylene glycol (DEG), and N-methylpyrrolidone-diethylene glycol at 50°C. The measurement of vapour-liquid equilibrium was carried out in a modified version of semimicrostill from foregoing paper. This still makes it possible to measure even at the pressures of the order 101 Pa. The dependence of the excess Gibbs energy on composition was expressed by the 4th order Redlich-Kister, Wilson, and NRTL equations. The systems EG-NMP and DEG-NMP exhibit negative deviations from ideal behaviour, EG with DEG form practically ideal solution.
Calculation of reaction energies for ion-molecule processes of first-row ions and their hydrides
Authors: Herman Zdeněk , Zahradník Rudolf
Published: May 2010

Reaction energies calculated by quantum chemical methods are compared with reaction enthalpies obtained on the basis of experimental heats of formation. Fifty six ion-molecule reactions (X+ + H2, XH+ + H2, where X is boron, carbon, or nitrogen, and reactions involving C2H2.+, C2H4.+, and C2H6.+) have been arranged into structurally related sets. Moreover, nine processes important in connection with the C2H2 formation in interstellar clouds are treated.
An homogeneous growth model of gallium arsenide epitaxial layers from the gas phase
Authors: Erdös Emerich , Voňka Petr , Stejskal Josef , Klíma Přemysl
Published: May 2010

This paper represents a continuation and ending of the kinetic study of the gallium arsenide formation, where a so-called inhomogeneous model is proposed and quantitatively formulated in five variants, in which two kinds of active centres appear. This model is compared both with the experimental data and with the previous sequence of homogeneous models.
Effect of internal diffusion on kinetics of liquid phase hydrogenation and disproportionation of the cyclohexene on palladium catalysts
Authors: Hanika Jiří , Ehlová Vladimíra
Published: May 2010

Kinetics of the side reactions represented by the system involving hydrogenation and disproportionation of cyclohexene on a commercial catalyst CHEROX 41-00 (3%Pd/C) and on a supported palladium catalyst prepared by impregnation of aluminia with aqueous palladium dichloride (2.15% Pd/γ-Al2O3) have been investigated. As follows from the effectiveness factors of internal diffusion for individual reactions, in the region of internal diffusion, cyclohexene hydrogenation is preferred compared to disproportionation. This finding can be related to the fact that while the rate of disproportionation is controlled by cyclohexene diffusion, the rate of hydrogenation is controlled by diffusion of hydrogen.
Study of polymer chain dynamics in solution by time-resolved spectrofluorometry
Authors: Fidler Vlastimil , Vajda Stefan , Limpouchová Zuzana , Dvořák Jiří , Procházka Karel , Bednář Bohumil
Published: May 2010

The methodology of polarization time-resolved fluorometry and interpretation of its results are outlined at a general level, and the measurement on and use of facilities of the Edinburgh Instruments Model 299T apparatus are discussed in detail. The dynamics of conformational changes in chains of poly(methacrylic acid) containing covalently bonded dansyl labels are studied in aqueous solutions at various pH. It is shown that at pH > 6, the shorter effective rational correlation time τr < 2 ns corresponds to the rotation of the free dansyl label about bonds by which it is attached to the polymeric chain; at pH < 4 the longer effective rational correlation time τr = 20-26 ns corresponds to the rotation of the compact spherical formation constituted by a part of the collapsed polymeric chain in which the label is fixed and whose relative molecular mass is approx. 15 000-20 000.
Structure and 13C MAR NMR spectra of various forms of isomeric methyl xylobiosides
Authors: Schraml Jan , Petráková Eva , Hirsch Ján , Teeaar Raivo , Lippmaa Endel
Published: May 2010

All so far known crystalline forms of all positional isomers of methyl β-D-xylopyranosyl-β-D-xylopyranoside were prepared and their high resolution 13C NMR spectra measured by the magic angle rotation (MAR) method using cross-polarization (CP). According to these spectra only two modifications of methyl 4-O-(β-D-xylopyranosyl)-β-D-xylopyranoside (modifications IVβ and IVγ) contain more than one molecule in the crystal elementary cell; in all other studied disaccharide samples all molecules are equivalent. The majority of carbon-13 chemical shifts could be assigned, at least partially, by a comparison with solution spectra. Some of the glycosidic carbons in the units with methyl aglycone (ring A) exhibit surprisingly large paramagnetic shifts with respect to the solution chemical shifts. Apparently, molecular structures at these sites in solids differ most from the average structures the molecules assume in the liquid phase. Assuming that solid state chemical shifts are affected also by similar factors as the shifts in solution, the methyl aglycone carbon chemical shifts indicate that the frozen conformation of the ring A in the solid is closer either to 1C4 conformation (modifications IIIα and II) or to 4C1 conformation (modification IVα) than are the respective equilibrium conformations in solution. Thermal analysis has proven, however, that the xylobioside forms with two nonequivalent molecules in the cell similarly as some other forms are indeed hydrates. Thus is shown that all the methyl xylobiosides are monomorphous, all the polymorphs are not true polymorphs but forms hydrated to a different extent.
Determinable parameters of the effective rotational Hamiltonians for excited vibrational states of semirigid symmetric top molecules of C4v, D4, D2h, andD2d symmetry
Authors: Sarka Kamil , Papoušek Dušan
Published: May 2010

A general method is described for obtaining the S functions which in the contact transformation of the vibration-rotation Hamiltonian of semirigid molecules with the fourfold symmetry axis eliminate the rotational and vibrational l-type operators and the Δk = ±4 centrifugal distortion operators from the λH1 terms of the expanded Hamiltonian. Explicit expressions are given for the vibration-rotation energy levels with independent effective spectroscopic parameters. Expressions are also given for the splittings of energy levels with essential resonances.
Kinetics of adsorption of heptane on active carbon supersorbon
Authors: Fajman Vratislav , Sedláček Zdeněk
Published: May 2010

Kinetics of the adsorption of heptane under different pressures and at different temperatures has been studied. Correlation of data according to a second-order equation was used to calculate half-time of adsorbate transport in pores. The correlation equation involves the effect of the pressure in pores for one component adsorption. The half-time was calculated from the whole course of kinetic isotherm. The empirical two-constant dependence of the half-time on pressure can be used to determine the possible mechanism of adsorbate transport in pores. In the adsorbent-adsorbate system studied the activation energy of heptane transport is 80 per cent of the value of isoteric heat. By using the end points of individual kinetic isotherms, the equilibrium isotherms at temperatures 0, 30, and 70 °C were constructed and these were correlated by Dubinin equation for the first structure type. Isochronous isotherms in coordinates of Langmuir and Dubinin equation were also constructed.
Calculation of the kinetics of crystallization based on a single batch experiment
Authors: Nývlt Jaroslav
Published: May 2010

The kinetics of crystal growth and nucleation in dependence on the supersaturation of a solution of KCL were evaluated based on a single batch crystallization experiment, where the supersaturation was monitored refractometrically and the product crystal size distribution was established at the end of the experiment. The crystal growth kinetic data obtained compare well with published values, for the nucleation data the agreement is less satisfactory.
Conditions of the Dieckmann condensation of alkyl 2-(N-methyl-N-(alkoxycarbonylmethyl)sulfamoyl)benzoates
Authors: Pátek Marcel , Hampl František
Published: May 2010

The Dieckmann condensation of alkyl 2-(N-methyl-N-(alkoxycarbonylmethyl)sulfamoyl)benzoates IIIa-IIIe with various bases affords alkyl 4-hydroxy-2-methyl-2H-1,2-benzothiazine-3-carboxylate 1,1-dioxides IVa-IVe which are intermediates in the synthesis of antiinflammatory drug piroxicam. The yields of benzothiazines IVa-IVe depend mostly on the nature of a base, reaction temperature and solvent used for these condensations. Hitherto undescribed esters IIIb-IIIe were synthesized and their structures were confirmed by 1H and 13C NMR, and mass spectra.
Radiation-initiated addition of acetaldehyde to allylalcohol and conversion of the 1:2-telomer into 1-methyl-2,8-dioxabicyclo[4,2,1]nonane
Authors: Liška František , Fikar Jiří , Trška Petr , Valenta Miroslav
Published: May 2010

Radiation-initiated addition of acetaldehyde to allyl alcohol gave a mixture of 5-hydroxy-2-pentanone (1:1-adduct I), 2-methyl-2-(4-oxopentyloxy)tetrahydrofuran (II), 7-hydroxy-4-hydroxymethyl-2-heptanone (1:2-telomer III) and 1,1-bis(4-oxopentyloxy)ethane (IV). The telomer III was dehydrated to afford 3-acetonyltetrahydropyran (IV), 1-methyl-2,8-dioxabicyclo[4.2.1]nonane (VI) and 3,10-dimethyl-4,11,16,17-tetraoxatricyclo[8.4.2.23,8]octadecane (VII).
The hydroalumination-iodination of enyne α-alcohols: Synthesis of 3-methyl-2,4-alkadien-1-ols
Authors: Khrimyan Ashot P. , Gharibyan Oganes A. , Streinz Ludvík , Wimmer Zdeněk , Romaňuk Miroslav , Badanyan Shaliko O.
Published: May 2010

It has been found that the reaction course of hydroalumination-iodination using 2-methyl-5-hexen-3yn-2-ol and (6E)-9,13-dimethyl-6,12-tetradecadien-4-yn-3-ol as substrates is ambiguous. The subsequent reaction of lithium dimethyl cuprate with iodo dienols unlike that of iodo alkenols is non-stereoselective. These reactions have been used for the synthesis of a juvenile hormone mimic (4E, 6E)-5,9,13-trimethyl-4,6,12-tetradecatrien-3-ol.
Potential antidepressants: 2-(Methoxy- and hydroxyphenylthio)benzylamines as selective inhibitors of 5-hydroxytryptamine re-uptake in the brain
Authors: Jílek Jiří , Šindelář Karel , Pomykáček Josef , Kmoníček Vojtěch , Šedivý Zdeněk , Hrubantová Marta , Holubek Jiří , Svátek Emil , Ryska Miroslav , Koruna Ivan , Valchář Martin , Dlabač Antonín , Metyšová Jiřina , Dlohožková Nataša , Protiva Miroslav
Published: May 2010

2-, 3- and 4Methoxythiophenol, and 2,4-, 2,5- and 3,4-dimethoxythiophenol were transformed in two steps to the corresponding 2-(methoxyphenylthio)benzoyl chlorides XIII which were reacted with ammonia, methylamine, diethylamine, dipropylamine, and di(2-propyl)amine to give the amides XIV-XIX. These were reduced mostly with lithium aluminium hydride to the amines II-VII. These methoxylated amines were demethylated mostly either by heating with pyridine hydrochloride or by treatment with boron tribromide. Some of the 2-(methoxy- and hydroxy-phenylthio)benzylamines prepared, especially compounds II, III, XXI, and XXII, indicated properties of potential antidepressants being highly active and selective inhibitors of 5-hydroxytryptamine re-uptake in the brain structures and having the typical antireserpine activity. The most interesting compound of the series is XXIb (hydrogen maleate VUFB-15 468) which is undergoing preclinical studies. On the basis of its structure, some further compounds (XXVII–XXIX, XXXIX-XLI) were prepared by various methods.
Effects of Ramadan on physical performance: chronobiological considerations
Authors: Waterhouse Jim
Published: May 2010

This article focuses on changes in Ramadan during the course of the waking day in physical performance, mental performance and gastrointestinal function. Possible explanations of the changes are considered by reference to the roles of the body clock and external factors such as the environment and the individual's lifestyle. The effects of these factors upon training schedules and upon changing the times of training are then discussed in terms of physiology and biochemistry. Delaying the time of training until after sunset has advantages and disadvantages, but it is a regimen that is unlikely to be widely accepted in non-Muslim countries. It is clear that the detailed nature of the problems involved and dealing with them in a manner based upon a firm body of knowledge requires far more experimental investigation.
Intentional versus unintentional contact as a mechanism of injury in youth ice hockey
Authors: Darling Scott R , Schaubel Douglas E , Baker John G , Leddy John J , Bisson Leslie J , Willer Barry
Published: May 2010

Background

Youth ice hockey injury rates and mechanisms have been described by various classification systems. Intentional versus unintentional contact was used to classify mechanisms of injuries. All injuries (n=247) in one youth hockey programme over a 5-year period were recorded and included in the analysis.

Purpose

To evaluate youth ice hockey injuries and compare programmes that allow body checking versus programmes that do not allow body checking. A primary goal was to determine whether programmes that allow body checking have increased injury rates from intentional body contact. Another goal was to describe the rates of injury across ages, levels of competitive play and during games versus practices.

Methods

Rates of injury were compared for three levels of competition (house, select and representative) for approximately 3000 boys aged 4–18 years over a 5-year period. This represents 13 292 player years. Data were collected prospectively in this cohort study. All injuries were reported prospectively by a designated team official and verified by a physician. The log injury rate (per 1000 player hours) was modelled via Poisson regression with log player hours used as an offset. Rate ratio was used to explain the covariate-adjusted injury rate for each of three groups (all injuries, intentional injuries, unintentional injuries).

Results

Unintentional contacts accounted for 66.0% of overall injuries (95% CI 60.0 to 72.0), compared with 34.0% from intentional contacts (p<0.001;Z=5.25). Serious injuries (fractures, dislocations, concussions) resulted more often from unintentional collisions (p=0.04). Players in more competitive leagues that allow body checking had a greater incidence of total injuries than less competitive leagues.

Conclusions

Most injuries in the youth hockey programme studied were the result of unintentional contact, and were generally more severe. These findings were not expected given previously published research.
Vitamin and mineral supplementation effect on muscular activity and cycling efficiency in master athletes
Authors: Louis Julien , Hausswirth Christophe , Bieuzen François , Brisswalter Jeanick
Published: May 2010

The influence of vitamin and mineral complex supplementation on muscular activity and cycling efficiency was examined in elderly endurance-trained master athletes during a heavy cycling trial. Master athletes were randomly assigned in a double-blind process to 1 of 2 treatment groups: antioxidant supplementation (n = 8: As group) or placebo (n = 8: Pl group) for 21 days. After that time, each subject had to perform a 10-min session of cycling on a cycloergometer at a heavy constant intensity. Twenty-four to 48 h after this session, subjects performed an isometric maximal voluntary contraction before and immediately after a fatiguing strength training (leg press exercise) and the same 10-min cycling test after fatigue. Isometric maximal voluntary force (MVF) of knee extensors was assessed before and after fatigue. Electromyographic (EMG) activity of the vastus medialis, the vastus lateralis (VL), and the biceps femoris was recorded with surface EMG. The knee-extensors MVF after the fatiguing exercise was reduced in similar proportions for both groups (As, –10.9%; Pl, –11.3%, p < 0.05). This MVF loss was associated with a significant reduction in EMG frequency parameters for both groups, with a lower decrease for the As group. Muscular activity and cycling efficiency during the cycling bouts were affected by the treatment. Cycling efficiency decreased significantly and the oxygen uptake slow component was higher after the fatiguing exercise for both groups. Furthermore, a decrease in cycling efficiency was associated with an increase in VL activity. However, these changes were significantly lower for the As group. The results of the present study indicate an overall positive effect of vitamin and mineral complex supplementation on cycling efficiency after fatigue, in the endurance-trained elderly.
Soy and the exercise-induced inflammatory response in postmenopausal women
Authors: Beavers Kristen M. , Serra Monica C. , Beavers Daniel P. , Cooke Matthew B. , Willoughby Darryn S.
Published: May 2010

Aging is associated with increasing inflammation and oxidative stress in the body, both of which can have negative health effects. Successful attenuation of such processes with dietary countermeasures has major public health implications. Soy foods, as a source of high-quality protein and isoflavones, may improve such indices, although the effects in healthy postmenopausal women are not well delineated. A single-blind, randomized controlled trial was conducted in 31 postmenopausal women who were assigned to consume 3 servings of soy (n = 16) or dairy (n = 15) milk per day for 4 weeks. Parameters of systemic inflammation (tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6)) and the oxidative defense system (superoxide dismutase (SOD), glutathione peroxidase, cyclooxygenase-2) were measured post supplementation, before and after an eccentric exercise bout performed to elicit an inflammatory response. A significant group-by-time effect for plasma TNF-α was observed (p = 0.02), with values in the dairy group increased post supplementation and then decreasing into the postexercise period. Additionally, significant time effects were observed for plasma SOD (p < 0.0001) and IL-6 (p < 0.0001) in the postexercise period. Overall results from our study do not support the notion that 4 weeks of daily soy milk ingestion can attenuate systemic elevations in markers of inflammation or oxidative defense. However, data do suggest that the downhill-running protocol utilized in this study can be effective in altering systemic markers of inflammation and oxidative defense enzyme activity, and that the ingestion of soy may help prevent fluctuations in plasma TNF-α.
Medical students’ perceptions of nutrition education in Canadian universities
Authors: Gramlich Leah M. , Olstad Dana Lee , Nasser Roseanne , Goonewardene Laki , Raman Maitreyi , Innis Sheila , Wicklum Sonja , Duerksen Donald , Rashid Mohsin , Heyland Daren , Armstrong David , Roy Claude
Published: May 2010

Patients routinely seek physicians’ guidance about diet and the relation between nutrition and the prevention and treatment of disease. However, the adequacy of nutrition instruction in undergraduate medical education is questionable. The purpose of this study was to investigate Canadian medical students’ perceptions of and satisfaction with their education in nutrition. At 9 universities across Canada, a 23-item survey questionnaire was distributed in English and French to undergraduate medical students after at least 8 months of medical school. Overall, 9 of 17 universities participated in the survey, and 933 of the 3267 medical students approached completed the survey (response rate, 28.6%). Mean satisfaction with nutrition instruction received during medical school was 4.7 (±0.06) on a scale of 1–10, where 1 is very dissatisfied and 10 is very satisfied, and there were significant differences among schools (p < 0.0001). Students were comfortable in their ability to counsel patients regarding basic nutrition concepts and the role of nutrition in prevention of disease, but were much less comfortable discussing the role of nutrition in the treatment of disease and nutrient requirements across the lifecycle, and in identifying credible sources of nutrition information. Of the 933 respondents, 87.2% believe that their undergraduate program should dedicate more time to nutrition education. The amount of nutrition instruction correlated with student satisfaction (p < 0.0001), but varied among schools. A significant number of students are dissatisfied with the nutrition education they receive and their ability to provide relevant and appropriate nutrition counselling. This study paves the way for further discussions and development of strategies to improve nutrition education in medical schools in Canada.
Effect of milk-based carbohydrate-protein supplement timing on the attenuation of exercise-induced muscle damage
Authors: Cockburn Emma , Stevenson Emma , Hayes Philip R. , Robson-Ansley Paula , Howatson Glyn
Published: May 2010

Exercise-induced muscle damage (EIMD) leads to decrements in muscle performance and increases in intramuscular enzymes measured in the plasma, and to delayed onset of muscle soreness (DOMS), partly due to the activation of degradative pathways. It has been shown that milk-based carbohydrate-protein (CHO-P) can limit changes in markers of EIMD, possibly by attenuating protein degradation and (or) increasing protein synthesis. However, the timing of supplementation has received limited attention, and this may alter the response. This study examined the effects of acute milk-based CHO-P supplementation timing on the attenuation of EIMD. Four independent matched groups of 8 healthy males consumed milk-based CHO-P before (PRE), immediately after (POST), or 24 h after (TWENTY-FOUR) muscle-damaging exercise. Active DOMS, isokinetic muscle performance, reactive strength index (RSI), and creatine kinase (CK) were assessed immediately before and 24, 48, and 72 h after EIMD. POST and TWENTY-FOUR demonstrated a benefit in limiting changes in active DOMS, peak torque, and RSI over 48 h, compared with PRE. PRE showed a possible benefit in reducing increases in CK over 48 h and limiting changes in other variables over 72 h. Consuming milk-based CHO-P after muscle-damaging exercise is more beneficial in attenuating decreases in muscle performance and increases in active DOMS at 48 h than ingestion prior to exercise.
Vitamin D supplementation of Canadian infants: practices of Montreal mothers
Authors: Gallo Sina , Jean-Philippe Sonia , Rodd Celia , Weiler Hope A.
Published: May 2010

Health policy in North America advocates that all breastfed infants receive a vitamin D supplement of 400 IU per day for the primary prevention of rickets. Despite this recommendation, rickets still occurs in Canada. It is not known whether vitamin D deficiency in the Canadian population is solely attributable to inadequacies in vitamin supplementation. Thus, the evaluation of current practices, including awareness and compliance with recommendations, is clearly needed. The objective of this study was to describe the vitamin D supplementation practices of mothers of newborns living in the Montreal area. This was a cross-sectional telephone survey of 343 mothers delivering a healthy term infant from December 2007 to May 2008 at the Royal Victoria Hospital (Montreal, Que.). Ninety percent of all mothers breastfed their infants during the first 6 months; 53% did so exclusively. Of mothers exclusively breastfeeding, 74% reported meeting the Health Canada recommendation. The main reason for not adhering to the recommendation was the assumption by mothers who began to feed fortified formula (400 IU·L–1) that supplementation was no longer necessary. Fifty percent of infants receiving mixed feedings without supplementation prior to 6 months did not achieve the recommended intake. Receiving advice about supplementation and the higher education of mothers were significant positive determinants of supplementation practices. This work identified infants consuming mixed feedings and those consuming only formula in the first 6 months as groups at high risk for not meeting the recommended 400 IU·day–1 of vitamin D. Therefore there may still be gaps in knowledge regarding vitamin D supplementation.
High-intensity interval training increases SIRT1 activity in human skeletal muscle
Authors: Gurd Brendon J. , Perry Christopher G.R. , Heigenhauser George J.F. , Spriet Lawrence L. , Bonen Arend
Published: May 2010

The effects of training on silent mating-type information regulator 2 homolog 1 (SIRT1) activity and protein in relationship to peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) and mitochondrial content were determined in human skeletal muscle. Six weeks of high-intensity interval training (∼1 h of 10 × 4 min intervals at 90% peak oxygen consumption separated by 2 min rest, 3 days per week) increased maximal activities of mitochondrial enzymes in skeletal muscle by 28% to 36% (citrate synthase, β-hydroxyacyl-coenzyme A dehydrogenase, and cytochrome c oxidase subunit IV) and PGC-1α protein (16%) when measured 4 days after training. Interestingly, total muscle SIRT1 activity (31%) and activity per SIRT1 protein (58%) increased despite decreased SIRT1 protein (20%). The present data demonstrate that exercise-induced mitochondrial biogenesis is accompanied by elevated SIRT1 activity in human skeletal muscle.
Improvements of conventional methods in railway track analysis and design
Authors: Sadeghi J. , Barati P.
Published: May 2010

The aim of this research is to improve the accuracy of conventional railway design methods by addressing the main track substructure parameters omitted in the current track design approach. Nonlinear and discrete properties of the track support system were studied and their influence on the calculation of railway design parameters was measured by conducting a field investigation and using finite element analysis. It was demonstrated that wheel loads and accumulative track loading are the key factors influencing nonlinear behavior of the track support system. Mathematical expressions were developed for the impact of the nonlinearity of the track support system based on the track analysis results, and correction factors were established for rail bending moments and rail deflections calculated by current methods. It was shown that the incorporation of these factors improves the accuracy and reliability of the conventional track design method.
Bond characteristics of coarse sand coated interface between stay-in-place fibre-reinforced polymer formwork and concrete based on shear and tension tests
Authors: Cho Jeong-Rae , Cho Keunhee , Park Sung Yong , Kim Sung Tae , Kim Byung-Suk
Published: May 2010

This study examined the effect of aggregate size and density on the shear and tensile bond characteristics of the coarse sand coated interface between stay-in-place fibre-reinforced polymer (FRP) formwork and concrete. Shear and tension tests were performed for five test variables according to aggregate size and density. Based on the test results, the appropriate size and distribution density of the aggregates is examined. In addition, based on the shear test results, the local shear bond stress-slip model for each of the test variables was derived through an optimization process.
Turbulence measurements in the impinging region of a circular jet
Authors: Rajaratnam N. , Zhu D. Z. , Rai S. P.
Published: May 2010

This note presents the results of turbulence measurements in the impinging region of a circular jet of diameter d with a Reynolds number of 105 impinging on a smooth wall located at a distance H equal to 18.5d. Even though the impinging region starts approximately at x/H = 0.860 (where x is the distance from the nozzle), the mean velocity profiles were found to be similar for x/H up to about 0.930 when normalized by the local maximum value. The normalized profiles of the turbulent shear stress and normal stresses in the axial, radial, and circumferential directions were also found to be similar. The variation of the scales for these turbulence profiles was found to be gradual for x/H up to about 0.960 and then rapid near the impinging wall. The corresponding length scales also showed a similar type of variation. The measurements also show that turbulence in the impinging jet drops significantly very near the impinging wall.
Effective placement of dangerous goods cars in rail yard marshaling operation
Authors: Bagheri Morteza , Saccomanno F. Frank , Fu Liping
Published: May 2010

Train derailments are important safety issues, and they become even more critical when dangerous goods (DG) are involved. This paper is concerned with mitigating derailment risk through improved operational strategies, with a specific focus on DG marshalling practices in the train-assembly process. A new modelling framework is proposed to investigate how the position of DG railway cars affects their chances of being involved in a derailment as the train travels over a given track segment. The underlying research problem can be formulated as a linear integer programming technique. However, since solving this formulation is computationally intractable, a heuristic method has been developed based on a genetic algorithm that gives a near-optimum solution. The proposed model is applied to a hypothetical rail corridor to demonstrate how effective marshalling of DG along a train can reduce overall derailment risks.
Comparison of reduction efficiency of woven straw for entrained emissions of particulate matter with diameters less than 10 µm (PM10) and less than 2.5 µm (PM2.5) from exposed areas at construction sitesA paper submitted to the Journal of Environmental Engineering and Science.
Authors: Su Kuo-Tung , Chang Yu-Min , Hu Wei-Hsing , Chen Shiao-Shing , Wu Chao-Hsiung , Lin Chi-Kang
Published: May 2010

From an engineering application point of view in reducing fugitive particulate matter emissions, this paper presents experimental data comparing the efficiency of woven straw at reducing entrained emissions of particulate matter with diameters less than 10 µm (PM10) with that for particulate matter with diameters less than 2.5 µm (PM2.5) at construction sites. A series of field-analogous experiments were carried out to continuously measure PM10 and PM2.5 using laser particle monitors in an artificial wind tunnel system. It was found that the efficiency of woven straw at reducing either PM10 or PM2.5 is significantly dependent on the woven straw coverage ratio. The maximum reduction efficiencies for PM10 and PM2.5 are about 40% and 12%, respectively. Note that the reduction efficiencies approach zero as the coverage ratio is less than about 40%. Total elimination of PM2.5 and PM10 emissions is not possible, even using full-coverage woven straw. Reduction of PM2.5 emissions is less efficient than that of PM10 emissions using woven straw, and this trend is likely more obvious with an increase in the woven straw coverage ratio. The ratio of reduction efficiencies (R) between PM2.5 and PM10 for woven straw decreased slightly with an increase in the woven straw coverage ratio. Overall, for wind speeds of 0.5–3.0 m/s, silt contents of 4.8%–21.0%, and soil moisture contents of 10%–30% as used in this work, the average value of R is 0.31. The effects of wind velocity, silt content, and moisture content on the reduction efficiencies are also discussed.
Anaerobic treatment of concentrated latex processing wastewater in two-stage upflow anaerobic sludge blanketA paper submitted to the Journal of Environmental Engineering and Science.
Authors: Jawjit Siriuma , Liengcharernsit Winai
Published: May 2010

This study aims to investigate treatment performance of the two-stage upflow anaerobic sludge blanket (UASB) applied to concentrated latex processing wastewater in Thailand. First, optimal conditions including the hydraulic retention time (HRT) in the acid tank and the UASB tank, pH, and temperature (mesophilic and thermophilic) were determined. It was found that the HRT at 24 h and 48 h were the optimal HRT for the acid tank and the UASB tank, respectively. The pH of the system should be controlled at 7 to prevent rubber coagulation and to achieve high treatment performance, and the mesophilic condition (35°C) was found to be the optimal temperature. Second, the two-stage UASB was applied with the optimal conditions mentioned earlier with real wastewater at a latex mill. It was found that methane production was about 0.116 L CH4/g COD removed (16.3–22.8 m3CH4/d), and average chemical oxygen demand (COD) and suspended solids (SS) removal efficiency were about 82% and 92%, respectively. In case of SS removal, the results revealed that the two-stage UASB was capable of overcoming the limitations of the single-stage UASB in treating concentrated latex effluent. The results indicated that application of the two-stage UASB to concentrated latex processing wastewater is feasible. Nevertheless, combination with other treatment systems (e.g., oxidation pond, aerated lagoon) is necessary to meet Thailand's industrial effluent standards (in the case of COD).
Production of indole-3-propanoic acid and 3-(p-hydroxyphenyl)propanoic acid by Clostridium sporogenes: a convenient thin-layer chromatography detection system
Authors: Jellet Joanne J. , Forrest Thomas P. , Macdonald Ian. A. , Marrie Thomas J. , Holdeman Lillian V.
Published: May 2010

Indole-3-propanoic acid (IPA), 3-(p-hydroxyphenyl)propanoic acid (HPPA), and 3-phenylpropanoic acid (PPA) were present in the spent bacterial media of Clostridium sporogenes (20/20 strains) and C. cylindrosporum (1/1 strains), but absent in 32 other clostridial species (74 strains) tested. Both IPA and HPPA (but not PPA) could be readily detected by thin-layer chromatography and p-hydroxybenzaldehyde spray reagent. IPA forms a scarlet complex with p-hydroxybenzaldehyde which shifts to purple and remains stable for up to 6 weeks. IPA can be detected in acidified extracts of C. sporogenes by a simple spot test. The structures of IPA and HPPA were confirmed by nuclear magnetic resonance (nmr) and mass spectroscopy and their formation was detected by the absorbance at 280 nm. Addition of one of the precursor amino acids (L-tryptophan, L-tyrosine, or L-phenylalanine) to the medium greatly enhanced formation of the corresponding deaminated acid and depressed the formation of the other two acids. The products IPA, HPPA, and PPA, at 10−3M, and spent bacterial media were negative in the direct Ames's assay for mutagenicity and noncytotoxic towards MRC-S cells.
Arginine synthesis and nitrogen excretion in the myxomycete Physarum polycephalum
Authors: Prescott Lansing M. , Rector James T. , Freund Ronald K. , Jacobson Denley B.
Published: May 2010

The nitrogen excretory metabolism of the myxomycete Physarum polycephalum was studied. When cultured in partially defined broth medium or on agar, the principal excretory product was ammonia nitrogen. A small, variable quantity of urea was excreted in liquid culture. No uric acid or other purines were detected in the cultures. When microplasmodia were incubated with sodium [14C]bicarbonate, radioisotope was incorporated into citrulline, arginine, and urea. Incubation with L-[carbamoyl-14C]citrulline yielded labelled arginine, urea, and CO2. Substantial urease activity was found in extracts of the microplasmodia. These results, in conjunction with the lack of an absolute nutritional requirement for arginine, provide evidence that Physarum has a functional arginine biosynthetic pathway, an arginase, and a urease.