historical methods for the determination of methylxanthines

... growth of the assay organism This limits the accumulation of the vitamin in the bacterial cell and thus maintains the sensitivity of the assay 3 Assay (basal) media to permit quantitation of the ... becauseturbidity is a measure of the rate of growth rather than the extent ofgrowth, and small differences in the temperature between tubes at thestart of the incubation influence the growth rate All tubes ... growth along the line of the stab Since the growth rate of an organism is a function oftemperature, the incubation must be precisely controlled to within+0.58C of the selected temperature The stab

Ngày tải lên: 11/04/2017, 11:13

... include the elucidation of the nucleation ics and formation mechanism of SAs, the delineation of the operating parameterspace under which SAs form and the mathematical modeling thereof Owing tothe ... [44] or in the presence of solvent [45], theprevention of which is of paramount importance in the final formulation of soliddosage forms Therefore, until these issues all get resolved, the development ... by the surface properties and the geometry of themicrochannel, the presence of surfactants and the properties of the immisciblephases [120]–[123] By choosing the right combination of the aforementionedconditions,

Ngày tải lên: 09/09/2015, 11:29

... 1PART I : DEVELOPMENT OF NOVEL METHODS FOR THE SYNTHESIS OF HOMOALLYLIC ALCOHOLS PART II : MULTIGRAM SYNTHESIS OF Trang 2PART I : DEVELOPMENT OF NOVEL METHODS FOR THE SYNTHESIS OF HOMOALLYLIC ALCOHOLS ... 14Among the many methods for the synthesis of homoallylic alcohols, the most frequently employed methodology is the allylation of aldehydes and ketones with allylic metals (Scheme 1).5 The use of ... cases, the whole rearrangement is thermodynamically favorable and a steric effect is the driving force of this reaction The preservation of the stereocenter and olefin geometry together with the

Ngày tải lên: 16/09/2015, 17:11

... Diagnosis Methods for the Evaluation of Mechanical and Magnetic Performance of Hard Disk Drives ZHU JIN （B.Eng (hons) HUST, P.R.China） A THESIS SUBMITTED FOR THE DEGREE OF MASTER OF ENGINEERING ... recession of the read/write transducers from slider surface Here, flying height refers to the spacing between the mean plate of the disk surface profile and the mean plate of the slider surface profile ... model [15] The advantage of writing process based methods is its testing range The disadvantage of such methods is its resolution On the other hand, the reading process based method is of the advantage

Ngày tải lên: 05/10/2015, 22:15

... funnel for extraction and at the same time as a syringe for direct injection of the extract into a GC or GC-MS for analysis The main feature of this method was the use of smaller amounts of the ... MICROEXTRACTION FOR THE DETERMINATION OF POLLUTANTS IN COMPLEX MATRICES SHU YAN(B Sc.) A THESIS SUBMITTED FOR THE DEGREE OF MASTER OF SCIENCE DEPARTMENT OF CHEMISTRY NATIONAL UNIVERSITY OF SINGAPORE ... into the hollow fiber These two steps were performed in n-nonane For solvent impregnation, the fiber was dipped with n-nonane for 10s The solvent entered through the pores of the fiber into the

Ngày tải lên: 22/10/2015, 21:08

... low viscosity of chloroform impeded the stability of the organic phase immobilized in the hollow fiber pores due to dissolution of chloroform in the midst of extraction n-Octanol was the only solvent ... orders of magnitude in the concentration range, 0.2-200 ppb, with r2 values >0.992 for most of the analytes The RSD for these compounds were between 7.4-11.8% The LODs for these drugs were in the ... favor of the deionization of analytes and to facilitate their distribution to the organic phase With the knowledge of the pKa value(s) of analytes would allow us to manipulate the acidity of the

Ngày tải lên: 10/11/2015, 11:00

... equal to the combined uncertainty of the determinations of the analyte contents of both the test sample and the blank value The magnitude of both the uncertainties of the results for the test ... [21] The number of determinations of the blank value in relation to the determinations of the test sample is important with regard to the uncertainty of the blank-value-corrected-result of the ... columns for the clean up of extracts of fatty food The eluent was a mixture of diethyl ether (20 %) and n-hexane (80 %) Trang 14Florisil was also employed for trapping of the analytes in the sweep

Ngày tải lên: 06/10/2016, 09:27

... Children:An Update of the 1987 Task Force Recommendations— Executive Summary Thomas A Nakagawa, MD, FAAP, FCCM 2.Report of Special Task Force Guidelines for determination of brain death in children ... All aspects of the clinical examination, including the apnea test, or ancillary studies must be appropriately documented Trang 154 References1 Guidelines for the Determination of Brain Death ... Trang 1Guidelines for the Determination of Brain Death in Infants and Children Trang 2DEFINITION OF BRAIN DEATH (Term Newborns 37 Weeks Gestational Age to Children 18 Years of Age) Brain death

Ngày tải lên: 14/11/2016, 06:25

... (b) the type and strength of the relationships, (c) the stability of clusters, and (d) whether the existence of a symptom cluster suggests an underlying mechanism Most of the attributes of a ... with the empirical identification of symptom clusters by multivariate methods? 1.6 Thesis Outline The research problem for this project was determined in the context of an emerging area of cancer ... of this thesis to symptom cluster research The strengths and limitations of the project are discussed, and recommendations are made for the application of specific analytical methods for symptom

Ngày tải lên: 07/08/2017, 15:27

... the detection of analytes in C4D depends on the difference of their conductivities from that of the separation medium, C4D is a good detection system for the determination of inorganic ions The ... to the higher conductivity of this BGE The electrolyte composed of Lac/β-Ala (Fig 1C) provided the best detection for most of the cations, compared to the other two BGEs studied 17 out of the ... mM) of Lac/β-Ala with 2 mM 18-Crown-6 were used to study the effect of the BGE concentration in the separation of the analytes The increase in the BGE concentration led to the prolongation of the

Ngày tải lên: 16/12/2017, 08:48

... repeatability Thus, the specified range of the method was 120 - 180 µg/mL * Determination of limit of determination and limit of quantification: The limit of detection and limit of quantification ... Chromatogram of the NIF standard sample using Xbridge column Figure 3: Chromatogram of the NIF standard sample using Phenomenex LUNA column The results of asymmetry factor, the number of theoretical ... retention time was 8.874 minutes On the chromatogram of the blank sample, no peak was observed in a period of 8 - 10 minutes The chromatograms of both the test sample and the standard sample had 1 peak

Ngày tải lên: 14/01/2020, 21:45

... reduction of the hydride-forming elements is fast and the reaction is completed before the reduction of the transition metal ion to the interfering species Also the separation of the hydrides from the ... 0.8␮g l−1 In the determination of As the samples prepared contained 800 mg Fe l−1. In the determination of Sb and Se the iron content of the samples was 2500 mg l−1. The total variance of the results ... Precision The precision of the methods was tested using one-way variance analysis The determinations were performed according to the arrangement in Fig 4 The concentrations of As, Sb and Se in the

Ngày tải lên: 22/04/2020, 19:51

... water formed during the reaction The fraction of the various forms of hydrogen can be determined from the ratios of the areas of the corresponding peaks The technique, implying measurement of the ... of the basic form of the indicator represents the measure of the quantity of acid centers present on the catalyst surface Obviously only the centers whose strength is higher than the pK, of the ... site is given by the slope of the linear portion of the curves of the type reported in Fig 20, while each point of the curve of Fig 21 corresponds to the specific activity of the various partially...

Ngày tải lên: 29/07/2015, 02:27

... of 95 ml) The A280 to A260 ratio of the UV-absorbing peak indicated it was composed mainly of nucleic acid In the profile of the NaOH-extracted polymer (B), the elution volume (80 ml) of saccharide ... compared to the other methods The SDS-extracted polymer included a small amount of material other than protein Furthermore, the steaming- and washing-extracted polymers contained large amounts of phosphorus ... buffer at a flow rate of ml/h and ml fractions were collected The void volume of the column was determined by the elution of Blue Dextran (Pharmacia) Other analyses - 147 - Journal of Water and Environment...

Ngày tải lên: 05/09/2013, 09:08

... for the issue of land suitable for the cultivation of plantation crop was formulated? The liberal rules formulated in Travancore during 1860s and subsequently in Cochin for the distribution of ... K) of the insulating medium and (iii) the reciprocal of the separation, t, between the plates The relation is given by'·' C = Kfj 1.3 t If the area of the plates and the separation between them ... has set in, is therefore an extremely difficult task" Numerous methods have been cited in literature for the measurement of the DRC of latex, of which the hydrometer":" is probably the most rapid...

Ngày tải lên: 23/03/2014, 21:21

... scrutinized the German version of this text Prof Nirschl suggested the idea of this book Prof Reimert organized the continuation of the research unit after the DFG funding as well as Prof Kasper, Prof ... derivation due to the time-dependence of the unit vectors Using the product rule for the derivation and the fact that the time derivative of the unit vector is the cross product of !rf with this ... the scaling of the argument on index k of the measured data in reciprocal space As the sum is finite, it only represents an approximation of the delta function The position of the origin and the...

Ngày tải lên: 29/05/2014, 18:32

... knowledge related to the mechanics of human movement The work at the University of California formed the basis for many of the fundamental techniques currently used for the study of human locomotion ... patterns of locomotion requires new methods that would limit the risk of producing artifact due to markers or the constraints of the testing methods For example, the constraints of the laboratory ... limiting the advancement of the study of human movement is the measurement of skeletal movement from markers or sensors placed on the skin The movement of the markers is typically used to infer the...

Ngày tải lên: 19/06/2014, 10:20

... in the sera of patient 313 had large deletions of a part of the 5'UTR These deletions are described in a separate report [21] The comparisons of the sera and isolates presented here were performed ... sequenced The dates of transmission indicate the date that HCV was added to the cells For the T1 through T7 isolates, the exact date of transmission sometimes wasn't known, but the first date of isolation ... (Figure 5) The change at position 204 was a reversion to the sequence found in the patient's sera For all three of these changes, one of the two isolates had the same base in that position as the patient...

Ngày tải lên: 20/06/2014, 02:20

... on the percentage of fully brown beans in the cut test 6: The effect of spreading of beans for two hours, prior to placement in boxes, on fermentation temperatures 7: The effect of spreading of ... reveals the presence of certain defects which may cause off-flavours and indicates the degree of fermentation of the beans which has a bearing on the flavour and quality of the beans The International ... case of larger quantities of beans e.g 250kg, partitioned boxes (Illustration 13) are used In this case, turning of beans is performed by shovelling them from one side of the partition to the other...

Ngày tải lên: 21/06/2014, 06:20

... nonconductive, they severely distort the signal in the detector; therefore, many systems remove the bubbles before the optical light path However, if the system removes the bubbles at any point within the ... depends on the size and range of the scales With practice, the recommended nomographs can be read with a precision of 1% However, the overall bias of the results depends on the bias of the analytical ... data applied to the nomographs and the validity of the theoretical equations and the numerical constants on which the nomographs are based An approximate check of the bias of the calculations...

Ngày tải lên: 29/07/2014, 18:58