Comparative Study Of Rate Research Articles

A Comparative Study of Rate of Speech in Different Dialects in Malayalam [Kannur, Eranakulam, Palakkad]

A Comparative Study of Rate of Speech in Different Dialects in Malayalam [Kannur, Eranakulam, Palakkad]

A comparative study of rate of fracture union in femur neck fractures- operated within 24 hours and after 24 hours and within 7 days, effect of tamponade on rate of union in cases fixed with cannulated cancellous screws

Background: Osteosynthesis of femoral neck fractures is particularly indicated in patients aged under 60years. A prolonged interval between the fracture and surgical fixation has been associated with avascular necrosis (AVN) of the femoral head. The primary objective of this study was to evaluate the association between the time to surgery and the rate of union in femur neck fractures.Methods: Patients with displaced fractures of the femoral neck (Garden III or IV) who underwent fixation with cannulated screws from August 2016 to August 2018 were evaluated retrospectively for the rate of union in femoral neck fractures.Patients were divided into two groups according to the time to surgery (within 24 hours and within 7days after 24 hours). Union rates were compared between the two groups.Results: 50 patients were included in the study; the duration of follow-up ranged from 12 to 24 months. The time from fracture to surgery ranged from 24 hours to 7 days. Fourty nine patients underwent surgery within 24 hours, and fourty eight patients underwent surgery within 7 days. There were two cases of femoral head necrosis. One patient had an associated infection. There were no statistically significant differences in the overall rate of union between the groups (p=0.999). None of the preoperative parameters or fracture characteristics were predictive factors for union. The only factor which affects the rate of union is inadequate reduction/fixation(odds ratio [OR]= 35.50, 95% confidence interval [CI]= 2.56 to 548.36, p=0.008).Conclusions: The interval between the occurrence of the injury and surgical fixation is not associated with rate of union in fractures of the femoral neck. Inadequate fracture reduction is a predictive factor in rate of union in femur neck fractures fixed with CC screws.

WITHDRAWN: Comparative study of rates of biosorption for selected single and mixed metal ions using natural products

WITHDRAWN: Comparative study of rates of biosorption for selected single and mixed metal ions using natural products

Ab initio calculations and RRKM/Master Equation modeling of chloroalkanes → alkenes + HCl reactions for use in comparative rate studies

This paper reports computations that were done in conjunction with an experimental study, reported in an accompanying paper, involving single pulse shock tube measurements of the thermal decomposition of 2-chloropropane, chlorocyclopentane, and chorocyclohexane. The overall aim of the combined work is to provide a well-defined, self-consistent, and reliable set of rate constants for those species over an extended temperature range for use as reference reactions in comparative rate studies. To provide additional validation of the results for the compounds of direct interest, the dehydrochlorination reactions of the related compounds chloroethane, 1-chloropropane, and 2-chlorobutane are also considered. The present work reviews and summarizes the literature information regarding the molecular properties, thermochemistry, and chemical kinetic data for the above six alkyl chlorides. Quantum chemical methods are used to compute the structure and energies of reactants, products, and transition states and the fundamental nature of these types of reaction (four-centered “semi-ion pair” transition states) is discussed. The experimental and theoretical results are compared in detail, and uncertainties are assessed. The computations are used, in conjunction with experimentally determined rate constants, to develop Rice–Ramsperger–Kassel–Marcus (RRKM)/Master Equation models and thereby allow extrapolation of the experimental data over an extended range of temperatures. © 2011 Wiley Periodicals, Inc.* Int J Chem Kinet 44: 369–385, 2012

Standard reactions for comparative rate studies: Experiments on the dehydrochlorination reactions of 2-chloropropane, chlorocyclopentane, and chlorocyclohexane

Single pulse shock tube studies of the thermal dehydrochlorination reactions (chlorocyclopentane → cyclopentene + HCl) and (chlorocyclohexane → cyclohexene + HCl) at temperatures of 843–1021 K and pressures of 1.4–2.4 bar have been carried out using the comparative rate technique. Rate constants have been measured relative to (2-chloropropane → propene + HCl) and the decyclization reactions of cyclohexene, 4-methylcyclohexene, and 4-vinylcyclohexene. Absolute rate constants have been derived using k(cyclohexene → ethene + butadiene) = 1.4 × 1015 exp(−33,500/T) s−1. These data provide a self-consistent temperature scale of use in the comparison of chemical systems studied with different temperature standards. A combined analysis of the present results with the literature data from lower temperature static studies leads to k(2-chloropropane) = 10(13.98±0.08) exp(−26, 225 ± 130) K/T) s−1; 590–1020 K; 1–3 bar k(chlorocylopentane) = 10(13.65 ± 0.10) exp(−24,570 ± 160) K/T) s−1; 590–1020 K; 1–3 bar k(chlorocylohexane) = 10(14.33 ± 0.10) exp(−25,950 ± 180) K/T) s−1; 590–1020 K; 1–3 bar Including systematic uncertainties, expanded standard uncertainties are estimated to be about 15% near 600 K rising to about 25% at 1000 K. At 2 bar and 1000 K, the reactions are only slightly under their high-pressure limits, but falloff effects rapidly become significant at higher temperatures. On the basis of computational studies and Rice–Ramsperger–Kassel–Marcus (RRKM)/Master Equation modeling of these and reference dehydrochlorination reactions, reported in more detail in an accompanying article, the following high-pressure limits have been derived: k∞ (2-chloropropane) = 5.74 × 109T1.37 exp(−25,680/T) s−1; 600–1600 K k∞ (chlorocylopentane) = 7.65 × 107T1.75 exp(−23,320/T) s−1; 600–1600 K k∞ (chlorocylohexane) = 8.25 × 109T1.34 exp(−25,010/T) s−1; 600–1600 K © 2011 Wiley Periodicals, Inc.* Int J Chem Kinet 44: 351–368, 2012

Comparative rate study on the acid and base catalyzed hydrolyses of formamide over a wide temperature range. Empirical relationship between k8 and k08

Comparative rate study on the acid and base catalyzed hydrolyses of formamide over a wide temperature range. Empirical relationship between k8 and k08

Structure–Activity Relationship Analysis of Pd–PEPPSI Complexes in Cross‐Couplings: A Close Inspection of the Catalytic Cycle and the Precatalyst Activation Model

A series of Pd-N-heterocyclic carbene (Pd-NHC) complexes with various NHC, halide and pyridine ligands (PEPPSI (pyridine, enhanced, precatalyst, preparation, stabilisation and initiation) precatalysts) were prepared, and the effects of these ligands on catalyst activation and performance were studied in the Kumada-Tamao-Corriu (KTC), Negishi, and Suzuki-Miyaura cross-coupling reactions. The lowered reactivity of more hindered 2,6-dimethylpyridyl complex 4 in the Negishi and KTC reactions is consistent with slow reductive dimerisation of the organometallic reaction partner during precatalyst activation. Comparative rate studies of complexes 1, 4 and 5 in the KTC and Suzuki-Miyaura reactions verify that 4 activated more slowly than the others. A potential on/off mechanism of pyridine coordination to NHC-Pd(0) is also plausible, in which the more basic pyridine stays bound for longer.

Comparative study of rate of weight loss among premorbid and healthy restrictive eaters

Initial body mass index (BMI) and rate of weight loss are compared between cohorts of pathological and healthy dieters. The eating disordered sample consists of young adults reported in case studies in the past ten years with a primary diagnosis of anorexia nervosa (AN). The healthy dieters were adolescents who participated in the National Longitudinal Survey of Adolescent Health and indicated at the time of study enrollment that they were trying to lose weight. At diet initiation, the anorexic sample had a mean BMI (kg/m2) of 20.5 while the healthy dieters had a mean of 24.8. The median rate of weight loss was -1.87 kg per month (1 pound per week) for individuals later diagnosed with AN, while the median weight change was 0.24 kg per month for the Add Health dieters, reflecting an actual gain of 0.13 pounds per week. These findings suggest that measurable physiological characteristics during the early phase of a diet could be predictive of pathological food restriction.

Comparative rate study on the oxidation of nicotinamide and isonicotinamide by permanganate in acidic medium

A comparative rate study on the oxidation of nicotinamide and isonicotinamide by potassium permanganate has been carried out in acidic solutions over an extended [H + ]-range (1x 10 -5 -1.0 mol L -1 ). Under the similar reaction conditions, the oxidation of pyridine is imperceptible. Further, in the absence of acid none of the two amides Is oxidized and in both cases, the N-protonated amide species appears to be reactive. For nicotinamide, the results are in agreement with the two-term rate law (A). The oxidation product was corresponding N-oxide. On the other hand, the oxidation of isonicotinamide follows a simpler rate law (B). The values of k 0 , K and k,K, for nicotinamide were found to be 5.5 x 10 -3 L mol -1 s -1 , 1.8 x 10 4 and 1.0 x 10 -2 L mol -1 s -1 , respectively at 35 °C. And for isonicotinamide, the k 0 and K values were 4.4 x 10 -3 L mol -1 s -1 and 5.6 x 103 respectively at 35 °C. The oxidation of nicotinamide is faster than the oxidation of isonicotinamide. It appears that the presence of -CONH 2 group at position 3 activates the ring nitrogen more for oxidation than the presence of this group at position 4.

Ruthenium(II)‐Catalyzed [2+2] Cycloadditions of anti 7‐Substituted Norbornenes

AbstractThe ruthenium(II)‐catalyzed [2+2] cycloadditions of anti 7‐substituted norbornenes with an alkyne were investigated. The cycloadditions were found to proceed with a high degree of stereoselectivity, giving only the exo stereoisomers in moderate to good yields using an improved protocol. Comparative rate studies between a variety of anti 7‐substituted norbornenes and an alkyne revealed that the reactivity of the alkene component decreases dramatically as the alkene becomes more electron deficient.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Left Ventricular Hypertrophy and Outflow Tract Obstruction in a Patient With Anorexia Nervosa

A 14-year-old girl was admitted to our hospital for hypoglycemia and cardiac tamponade. In the 14 months preceding this hospitalization, she became obsessed with food intake and exercise and developed amenorrhea, disturbed body image, and an intense fear of becoming fat. She subsequently lost 31 kg body weight (decreasing from 52 to 21 kg), meeting the diagnostic criteria for anorexia nervosa. Her rate of weight loss was almost constant for the first 11 months (1.6 kg/mo) but accelerated during the last 3 months before admission (4.7 kg/mo). Chest radiography after drainage of a pericardial effusion (Figure 1A) showed that the patient had an extremely small heart, with a cardiothoracic ratio of …

Comparative Study of Rate of Zonal Shortening Calculated from GEONET data and Distribution of Active Faults in Northeastern Japan Arc

Comparative Study of Rate of Zonal Shortening Calculated from GEONET data and Distribution of Active Faults in Northeastern Japan Arc

Mono- versus bidentate ligands in rhodium-catalyzed asymmetric hydrogenation. A comparative rate study.

Bidentate chiral phosphines are no longer essential for achieving a fast and highly enantioselective hydrogenation of α- or β-dehydroamino acid derivatives. In particular, a readily accessible and stable monodentate phosphoramidite can be highly effective in these asymmetric hydrogenations.

Mono- versus bidentate ligands in rhodium-catalyzed asymmetric hydrogenation. A comparative rate study.

[reaction: see text] Bidentate chiral phosphines are no longer essential for achieving a fast and highly enantioselective hydrogenation of alpha- or beta-dehydroamino acid derivatives. In particular, a readily accessible and stable monodentate phosphoramidite can be highly effective in these asymmetric hydrogenations.

Molecular Insights into Species Phylogeny, Biogeography, and Morphological Stasis in the Ancient Spider Genus Hypochilus (Araneae: Hypochilidae)

The spider genus Hypochilus is currently restricted to cool, moist microhabitats in three widely separated montane regions of North America, providing an opportunity to study both deep (i.e., continental level) and shallow (within montane region) biogeographic history. Members of the genus also retain many plesiomorphic morphological characteristics, inviting the study of comparative rates of morphological evolution. In this paper, Hypochilus phylogeny and associated evolutionary problems are addressed using both new molecular (28S nDNA and CO1 mtDNA) and previously published (K. M. Catley, 1994, Am. Mus. Nov. 3088, 1–27) morphological data. Although the molecular data provide limited resolution of root placement within Hypochilus, most analyses are at least consistent with morphology-supported montane relationships of (Rockies (California, Appalachian)). The monophyly of Hypochilus species distributed in the California mountains is ambiguous, with several analyses indicating that this fauna may be paraphyletic with respect to a monophyletic Appalachian lineage. The montane regions differ in consistent ways in depths of both mitochondrial and nuclear phylogenetic divergence. Molecular clock analyses, in combination with arthropod-based mtDNA rate calibrations, suggest that the regional faunas are of different ages and that speciation in all faunas likely occurred prior to the Pleistocene. Limited intraspecific sampling reveals extraordinarily high levels of mtDNA cytochrome oxidase sequence divergence. These extreme divergences are most consistent with morphological stasis at the species level, despite preliminary evidence that Hypochilus taxa are characterized by fragmented population structures.

Parasites, phylogeny and cospeciation

Host-parasite assemblages offer exciting possibilities for the comparative study of rates of speciation and evolution in different organisms. The basis for such studies must be a phylogenetic analysis of the host-parasite association. Some recent developments in this field are briefly reviewed and illustrated using phylogenies for pocket gophers and their chewing lice.

Thermal-Degradation of Polymers and Polymer Models. V. A Model for Copoly(styrene-methyl methacrylate)

The synthesis of (�)- and meso-dimethyl 2,3-dimethyl-2,3-bis(2′-methyl-2′-phenylpropyl)butane-dioate from methyl 2,4-dimethyl-4-phenylpentanoate , via a silyl enol acetal, is described. The X-ray structure of the meso isomer shows serious distortions from normal bond lengths and angles, most notably a length of 162.7(4) pm for the crowded central C-C bond. The compounds were synthesized as models for head-to-head units which might form by chain termination through dimerization of macroradicals during copolymerization of styrene and methyl methacrylate . Thermal degradation of the diphenyl -substituted diesters at 210° gave products which may have formed by plausible routes from radicals resulting from homolytic cleavage of the crowded C-C bond. Inclusion of the phenyl groups makes the molecules more crowded than the corresponding tetraesters which were reported earlier, and a comparative rate study shows that the aromatic compounds are less stable to heat as a result of the penultimate effects of greater crowding at carbons which are β to the thermally vulnerable bond.

Organoboranes. 47. An extremely facile elimination of alkenes from dialkylhaloboranes. A comparative rate study with related trialkylboranes

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOrganoboranes. 47. An extremely facile elimination of alkenes from dialkylhaloboranes. A comparative rate study with related trialkylboranesHerbert C. Brown, P. V. Ramachandran, and J. ChandrasekharanCite this: Organometallics 1986, 5, 10, 2138–2141Publication Date (Print):October 1, 1986Publication History Published online1 May 2002Published inissue 1 October 1986https://doi.org/10.1021/om00141a034RIGHTS & PERMISSIONSArticle Views146Altmetric-Citations10LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (515 KB) Get e-Alerts Get e-Alerts

Structures of three hydrogenation catalysts [(P-P)Rh(NBD)]ClO4 and some comparative rate studies where (P-P) = (.eta.5-R1R2PC5H4)(.eta.5-R3R4PC5H4)Fe (R1 = R2 = R3 = R4 = Ph; R1 = R2 = Ph, R3 = R4 = CMe3; R1 = R3 = Ph, R2 = R4 = CMe3)

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructures of three hydrogenation catalysts [(P-P)Rh(NBD)]ClO4 and some comparative rate studies where (P-P) = (.eta.5-R1R2PC5H4)(.eta.5-R3R4PC5H4)Fe (R1 = R2 = R3 = R4 = Ph; R1 = R2 = Ph, R3 = R4 = CMe3; R1 = R3 = Ph, R2 = R4 = CMe3)William R. Cullen, Tae Jeong Kim, Frederick W. B. Einstein, and Terry JonesCite this: Organometallics 1985, 4, 2, 346–351Publication Date (Print):February 1, 1985Publication History Published online1 May 2002Published inissue 1 February 1985https://doi.org/10.1021/om00121a027RIGHTS & PERMISSIONSArticle Views166Altmetric-Citations60LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (736 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

CARBONATE EROSION RATES IN SOUTHWESTERN WISCONSIN

Between 1977 and 1979 three sets of erosional weight loss tablets were em-placed in the karst of southwestern Wisconsin to measure both potential and actual rates of carbonate erosion. Tablets of Jamaican White Limestone, which has been used in many other karst areas, were used to gauge relative erosion potential while tablets of the local bedrock, Prairie du Chien dolomite, were used to assess absolute rates. Tablets of Yugoslavian limestone were emplaced as part of a world-wide study of comparative rates. Tablets were recovered in 1983 and 1984. Although potential erosion rates are similar to those in other carbonate areas, the sluggish dissolution of the indigenous dolomite retards karst development. Soil cover increases erosion rates and rates at a given depth are consistent over sites of up to 10 m2. The highest erosion rates were recorded by the Yugoslavian tablets but betweensite variations caution that results based on a single site may be unrepresentative. Over 37% of all tablets were affected by...