New Protocol for Twinning of Raman Devices Toward a Raman Intensity Harmonization.

The use of Raman spectroscopy has rapidly been on the rise across a great number of industries where comparability, reproducibility, and reliability of the data are of paramount importance. However, controlling the intensity of the Raman signal depends on a large number of factors such as the wavelength of the laser light, the optical components of each device, or the number of molecules in the illuminated volume. For this reason, in this study, a new protocol has been applied to twin Raman devices to achieve a conversion of the signal between them, by pairing the intensity response of the units using a reference sample. The new reference material is a homogenous dispersion of a 0.5 wt% anatase (titanium dioxide, or TiO2) in an epoxy resin matrix, with deviations <2.5% in Raman intensity across the reference material. The proposed protocol for Raman-twinned devices takes a well-defined approach that leads to obtaining a correction factor that relates the differences in the signal intensity between the two Raman devices, in order to obtain the same Raman intensity counts. The performance of the proposed method was evaluated based on the data from the devices, which presented the most common user cases: twinning Raman devices of the non-confocal same model for two different wavelengths; and twinning confocal and non-confocal devices. The results obtained show that the protocol has worked for both of the Raman twinning cases, allowing the Raman intensity harmonization of Raman spectra between two different devices.

Identification of the Remains of an Adult Using DNA from Their Deciduous Teeth as a Reference Sample.

In many forensic cases, the identification of human remains is performed by comparing their genetic profile with profiles from reference samples of relatives, usually the parents. Here, we report, for the first time, the identification of the remains of an adult using DNA from the person's deciduous teeth as a reference sample. Fragments of a skeletonized and burned body were found, and a short tandem repeat (STR) profile was obtained. A woman looking for her missing son went to the authorities. When the DNA profile of the woman was compared to a database, a positive match suggested a first-degree kinship with the person to whom the remains belonged. The woman had kept three deciduous molars from her son for more than thirty years. DNA typing of dental pulp was performed. The genetic profiles obtained from the molars and those from the remains coincided in all alleles. The random match probability was 1 in 2.70 × 1021. Thus, the remains were fully identified. In the routine identification of human remains, ambiguous STR results may occur due to the presence of null alleles or other mutational events. In addition, erroneous results can be produced by false matches with close family members or even with people who are completely unrelated to the victim, such that, in some cases, a probability of paternity greater than 99.99% does not necessarily indicate biological paternity. Whenever possible, it is preferable to use reference samples from the putative victim as a source of DNA for identification.

Age estimation by modified Suchey-Brooks method using three-dimensional reconstructed CT images of Chinese Han population.

The method proposed by Suchey-Brooks for adult age estimation based on the surface morphology of the pubic symphysis has been widely accepted. The applicability of the method varies considerably in different populations. The present study established a virtual reference sample and aimed to develop population-specific criteria that can be used for age estimation in different skeletal samples. First, The dry bone specimens from 100 individuals were compared with their corresponding three-dimensional (3D) reconstruction model and showed high inter-method agreement (k = 0.743-0.811), suggesting that the virtual bone model and physical bone specimens have comparable performances in describing the surface morphology of the pubic symphysis. We retrospectively collected clinical computed tomography (CT) data from 895 Chinese patients to create a virtual reference sample of the pubic symphysis. Based on the original Suchey-Brooks method, each of the 895 reference samples was assigned a phase, for each sex and phase, data on the mean age, standard deviation, and 95% age range of the corresponding sample were obtained, which was then used as the "method modified for Chinese" (modified method) and compared to the "SB method". Compared to the SB method, modified method had a lower inaccuracy in dry bones for males over 35 years and females over 45 years, in dry bone CT test sample for males over 55 years and females over 45 years, and in postmortem CT test sample for males over 35 years and females over 55 years. The modified method can improve the accuracy of age estimation for older samples over 40 years. It has shown considerable reliability when applied as a population-specific criterion, but its accuracy is still not sufficient, and caution is needed when using it.

Application of Microhaplotypes in Sibling Kinship Testing.

OBJECTIVES: To investigate the efficacy of different numbers of microhaplotype (MH) loci and the introduction of different reference samples on the identification of full sibling, half sibling and differentiation between full sibling and half sibling kinships, and to explore the effect of changing mutation rate on sibling testing. METHODS: First, a family map involving three generations was established, and four full sibling identification models, five half sibling identification models and five models distinguishing full and half siblings were constructed for different reference samples introduced. Based on the results of the previous study, two sets of nonbinary SNP-MH containing 34 and 54 loci were selected. Based on the above MH loci, 100 000 pairs of full sibling vs. unrelated individuals, 100 000 pairs of half sibling vs. unrelated individuals and 100 000 pairs of full sibling vs. half sibling were simulated based on the corresponding sibling kinship testing models, and the efficacy of each sibling kinship testing model was analyzed by the likelihood ratio algorithm under different thresholds. The mutant rate of 54 MH loci was changed to analyze the effect of mutation rate on sibling identification. RESULTS: In the same relationship testing model, the systematic efficacy of sibling testing was positively correlated with the number of MH loci detected. With the same number of MH loci, the efficacy of full sibling testing was better than that of uncle or grandfather when the reference sample introduced was a full sibling of A, but there was no significant difference in the identification efficacy of the four reference samples introduced for full sibling and half sibling differentiation testing. In addition, the mutation rate had a slight effect on the efficacy of sibling kinship testing. CONCLUSIONS: Increasing the number of MH loci and introducing reference samples of known relatives can increase the efficacy of full sibling testing, half sibling testing, and differentiation between full and half sibling kinships. The level of mutation rate in sibling testing by likelihood ratio method has a slight but insignificant effect on the efficacy.

Pre-analytical sample handling standardization for reliable measurement of metabolites and lipids in LC-MS-based clinical research.

The emerging disciplines of lipidomics and metabolomics show great potential for the discovery of diagnostic biomarkers, but appropriate pre-analytical sample-handling procedures are critical because several analytes are prone to ex vivo distortions during sample collection. To test how the intermediate storage temperature and storage period of plasma samples from K3EDTA whole-blood collection tubes affect analyte concentrations, we assessed samples from non-fasting healthy volunteers (n = 9) for a broad spectrum of metabolites, including lipids and lipid mediators, using a well-established LC-MS-based platform. We used a fold change-based approach as a relative measure of analyte stability to evaluate 489 analytes, employing a combination of targeted LC-MS/MS and LC-HRMS screening. The concentrations of many analytes were found to be reliable, often justifying less strict sample handling; however, certain analytes were unstable, supporting the need for meticulous processing. We make four data-driven recommendations for sample-handling protocols with varying degrees of stringency, based on the maximum number of analytes and the feasibility of routine clinical implementation. These protocols also enable the simple evaluation of biomarker candidates based on their analyte-specific vulnerability to ex vivo distortions. In summary, pre-analytical sample handling has a major effect on the suitability of certain metabolites as biomarkers, including several lipids and lipid mediators. Our sample-handling recommendations will increase the reliability and quality of samples when such metabolites are necessary for routine clinical diagnosis.

[Analysis on quality value transmitting of Qinggusan reference sample of classical prescription based on quantitative fingerprint technology].

Qinggusan is the 69th prescription in the first batch of "Catalogue of Ancient Chinese Classic Formulas". In modern clinical practice， Qinggusan is mainly used to treat noninfectious fever. However， because few studies on Qinggusan reference samples and their quality value transfer are available， the development and promotion of its compound preparations are restricted. Therefore， establishing an accurate and comprehensive quality control method to clarify the critical quality attributes of Qinggusan reference samples is of great importance. In this study， 15 batches of Qinggusan reference samples were processed to determine the range of their dry extract ratios. Quantitative high-performance liquid chromatography （HPLC） fingerprint analysis was performed using a Waters Symmetry Shield RP18 column （250 mm×4.6 mm， 5 µm） with acetonitrile-0.1% （v/v） formic acid aqueous solution as the mobile phase in gradient elution mode. The flow rate was 1.0 mL/min， the column temperature was 30 ℃， and the detection wavelength was 254 nm. The HPLC fingerprints of the Qinggusan reference samples were established under these conditions to evaluate their similarity. The established method was systematically validated and found to demonstrate good precision， repeatability， and sample stability. Subsequently， characteristic peaks were identified and attributed by HPLC-quadrupole-time-of-flight-mass spectrometry （HPLC-Q-TOF-MS） analysis. MS was performed in electrospray ionization mode， the data were collected in both positive- and negative-ion modes， and the detection range was m/z 50-2000. The contents and transfer rate ranges of the index components， namely， gentiopicrin， mangiferin， picroside Ⅱ， picroside Ⅰ， and glycyrrhizic acid， were determined to analyze the quality value transfer of the samples. The results demonstrated that the dry extract rate of the 15 batches of Qinggusan reference samples ranged from 24.10% to 26.88% and that their fingerprint similarities were generally greater than 0.95. Twelve common peaks were identified by reference identification， literature comparison， and high-resolution MS analysis. Twelve compounds， including six iridoid glycosides， two flavonoids， one alkaloid， one triterpenoid saponin， and two others. Among them， L-picein， androsin， picroside Ⅳ， picroside Ⅱ and picroside Ⅰ were from Picrorhizae Rhizoma， loganin acid， swertiamarin and gentiopicrin were from Gentianae Macrophyllae Radix， neomangiferin and mangiferin were from Anemarrhenae Rhizoma， dichotomine B was from Stellariae Radix， and glycyrrhizic acid was from Glycyrrhizae Radix et Rhizoma. The five key components presented good linear relationships in their respective linear ranges， and all correlation coefficients were higher than 0.999. The relative standard deviations （RSDs） of precision， stability， and repeatability were less than 1.3%. The average recoveries varied between 95.92% and 102.5%， with RSDs less than 3.9%； these values meet the requirements defined in the 2020 edition of the Chinese Pharmacopoeia. The contents of gentiopicrin， mangiferin， picroside Ⅱ， picroside Ⅰ， and glycyrrhizic acid in the 15 batches of reference samples were in the range of 17.92-27.55， 1.83-4.42， 23.08-36.44， 8.43-15.04， and 0.94-2.39 mg/g， respectively， and their transfer rates from the decoction pieces to the reference samples were 47.91%-63.95%， 22.96%-59.39%， 60.82%-77.82%， 64.25%-99.53%， and 15.30%-39.30%， respectively. In this study， the chemical components of Qinggusan reference samples were comprehensively identified and their quality value transfer was studied through the combination of HPLC fingerprinting and MS. Clarification of the critical quality attributes of Qinggusan reference samples could provide a basis for the quality control of Qinggusan compound preparations.

Characterization of irradiation channels in the carousel of TRIGA Mark I IPR-R1 research reactor, Brazil, aiming at the application of k 0-standardization method of neutron activation analysis.

New values of neutron fluxes and spectral parameters f and α were determined experimentally in all irradiation devices of the TRIGA Mark I IPR-R1 nuclear research reactor at Nuclear Technology Development Centre (CDTN), Belo Horizonte, Brazil. Sets of monitors Au, Fe, Zn and Zr were irradiated bare and Cd-covered, according to "Cd-ratio for multi-monitor" method. Values were validated by analysing the certified reference material BCR-320R irradiated in chosen channels. The calculations were made based on irradiation channel values and the average values of the Carousel. The results of E n -score point out that the k 0-method is producing reliable results. From now on, the values of mass fractions in several matrices, the production and studies with radioisotopes will be more accurate and the activities calculated more precisely.

Application of Microhaplotypes in Sibling Kinship Testing / 法医学杂志

OBJECTIVES@#To investigate the efficacy of different numbers of microhaplotype (MH) loci and the introduction of different reference samples on the identification of full sibling, half sibling and differentiation between full sibling and half sibling kinships, and to explore the effect of changing mutation rate on sibling testing.@*METHODS@#First, a family map involving three generations was established, and four full sibling identification models, five half sibling identification models and five models distinguishing full and half siblings were constructed for different reference samples introduced. Based on the results of the previous study, two sets of nonbinary SNP-MH containing 34 and 54 loci were selected. Based on the above MH loci, 100 000 pairs of full sibling vs. unrelated individuals, 100 000 pairs of half sibling vs. unrelated individuals and 100 000 pairs of full sibling vs. half sibling were simulated based on the corresponding sibling kinship testing models, and the efficacy of each sibling kinship testing model was analyzed by the likelihood ratio algorithm under different thresholds. The mutant rate of 54 MH loci was changed to analyze the effect of mutation rate on sibling identification.@*RESULTS@#In the same relationship testing model, the systematic efficacy of sibling testing was positively correlated with the number of MH loci detected. With the same number of MH loci, the efficacy of full sibling testing was better than that of uncle or grandfather when the reference sample introduced was a full sibling of A, but there was no significant difference in the identification efficacy of the four reference samples introduced for full sibling and half sibling differentiation testing. In addition, the mutation rate had a slight effect on the efficacy of sibling kinship testing.@*CONCLUSIONS@#Increasing the number of MH loci and introducing reference samples of known relatives can increase the efficacy of full sibling testing, half sibling testing, and differentiation between full and half sibling kinships. The level of mutation rate in sibling testing by likelihood ratio method has a slight but insignificant effect on the efficacy.

[Study on characteristic chromatogram and content determination of Wuzhuyu Decoction reference sample].

In this study, the critical quality attributes of Wuzhuyu Decoction reference sample were explored by using characteristic chromatogram, index component content and dry extract rate as indexes.The dissemination relationship of quantity value between medicinal materials-decoction pieces-reference sample was investigated to preliminarily formulate the quality standard of the reference sample.The characteristic chromatogram of 15 batches of Wuzhuyu Decoction was established by high performance liquid chromatography(HPLC) and the similarity analysis was conducted.Common peaks were demarcated and assigned to medicinal materials.Moreover, quantitative determination of limonin, evodiamine, rutaecarpine and ginsenoside Rb_1 of Wuzhuyu Decoction were performed.The dissemination of quantity value was explored combined with dry extract rate, similarity of characteristic chromatogram and transfer rate of index component content.A total of 18 common peaks were identified in the corresponding materials of Wuzhuyu Decoction reference sample, with the similarity of characteristic chromatogram greater than 0.9, and Fructus Evodiae, Radix Ginseng, Rhizoma Zingiberis Recens and Fructus Jujubae contributed 9, 5, 8 and 2 chromatographic peaks, respectively.The index component content of corresponding materials and the transfer rates of medicinal materials-decoction pieces and decoction pieces-reference sample of different batches of Wuzhuyu Decoction reference sample were as follows: the content of limonin was 0.16%-0.51%, and the transfer rates were 83.66%-115.60% and 38.54%-54.58%, respectively; the content of evodiamine was 0.01%-0.11%, the transfer rated were 80.80%-116.15% and 3.23%-12.93%, respectively; the content of rutaecarpine was 0.01%-0.05%, the transfer rates were 84.33%-134.53% and 5.72%-21.24%, respectively; the content of ginsenoside Rb_1 was 0.06%-0.11%, and the transfer rates were 90.00%-96.92% and 32.45%-67.24%, respectively.The dry extract rate of the whole prescription was 22.58%-29.89%.In this experiment, the dissemination of quantity value of Wuzhuyu Decoction reference sample was analyzed by the combination of characteristic chromatogram, index component content and dry extract rate.A scientific and stable quality evaluation method of the reference sample was preliminarily established, which provided basis for the subsequent development of Wuzhuyu Decoction and the quality control of related preparations.

International Round Robin Test of Thermoelectric Generator Modules.

The status of metrology for the characterization of thermoelectric generator modules (TEM) is investigated in this work by an international round robin (RR) test including twelve laboratories from nine countries on three continents. Measurements have been performed with three samples of a Bi2Te3-based commercial TEM type, which has prevailed over three competing types during previous tests on the short- and long-term stability. A comparison of temperature-dependent results is provided up to 200 °C hot side temperature for the maximum power output Pmax, the incident heat flow Q˙In (at maximum efficiency conditions), and the maximum efficiency ηmax. Data evaluation from all RR participants reveals maximum standard deviations for these measurands of 27.2% (Pmax), 59.2% (Q˙In), and 25.9% (ηmax). A comparison between RR data sets and reference data from manufacturer specifications shows high deviations of up to 46%, too. These deviations reflect the absence of measurement guidelines and reference samples and confirm the need for improvements in the standardization of TEM metrology. Accordingly, the results of the RR are presented against the background of our own investigations on the uncertainty budgets for the determination of the abovementioned TEM properties using inhouse-developed characterization facilities, which comprise reference and absolute measurement techniques for the determination of heat flow.

Meeting the COVID challenge: Optimizing vCD34+ in cryopreserved HPC samples for implementation of an external QA Program.

BACKGROUND: The COVID-19 pandemic has forced a fundamental change in the global procurement of allogeneic hematopoietic progenitor cells (HPCs) for transplantation. To better meet the emergent challenges of transporting cryopreserved allogeneic HPC during pandemics, there is an urgent need for External Quality Assurance (EQA) programs to evaluate reproducibility and harmonization of viable CD34+ cell (vCD34+) HPC enumeration, as the current EQA programs are unsuitable for analysis of vCD34+. The cost-effective distribution of HPC cryopreserved reference samples (CRSs) with acceptable reproducibility and specificity is key to the success of a vCD34+ EQA program. METHODS: Cryopreserved HPC samples (n = 11) were either stored on dry ice for 1 to 4 days or for 1 day followed by liquid nitrogen (LN) storage for 1 to 3 days to assess optimal conditions for vCD34+ EQA. Flow cytometric enumeration of vCD34+ HPCs was performed using a single platform assay combined with 7-AAD viability dye exclusion. The optimum transportation condition was validated in pilot and multicenter national studies (n = 12). RESULTS: A combination of 1 day on dry ice followed by LN storage stabilized viability compared with continuous storage on dry ice. This study demonstrates that dispatch of CRSs on dry ice to recipient centers across a distance of ≤4000 km within 26 h, followed by LN storage, resulted in reproducible intercenter vCD34+ enumeration. The estimated cost of safer and more convenient dry ice delivery is >20-fold lower than that of LN. CONCLUSION: This approach can form the basis for economically and scientifically acceptable distribution of CRSs for external vCD34+ EQA.

Chemical Composition Analysis and Characterization of Reference Sample of Huangqi Guizhi Wuwutang Based on UPLC-Q-TOF-MS / 中国实验方剂学杂志

ObjectiveTo analyze the chemical composition of the reference sample of Huangqi Guizhi Wuwutang （lyophilized powder）， and to provide quality markers for the formulation of quality standards of this formula. MethodUltra performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry （UPLC-Q-TOF-MS） was performed on a Waters ACQUITY UPLC™ HSS T3 column （2.1 mm×100 mm， 1.8 μm）， the mobile phase was methanol （A） -0.1% formic acid aqueous solution （B） for gradient elution （0-8 min， 1%-20%A； 8-10 min， 20%-30%A； 10-12 min， 30%-35%A； 12-14 min， 35%-40%A， 14-23 min， 40%-55%A， 23-27 min， 55%-99%A； 27-28 min， 99%A； 28-28.5 min， 99%-1%A； 28.5-30 min， 1%A）， the column temperature was 40 ℃， the injection volume was 2 μL， and the flow rate was 0.3 mL·min-1. The mass spectrometry data of the reference sample of Huangqi Guizhi Wuwutang （lyophilized powder） were collected under positive and negative ion modes. The conditions of mass spectrometry were electrospray ionization （ESI）， scanning range of m/z 50-1 200， and impact energy of 10-30 eV. UNIFI 1.8 and Progenesis QI 2.0 software were used to analyze and characterize the chemical constituents in reference sample of Huangqi Guizhi Wuwutang （lyophilized powder） combined with reference comparison and literature review. ResultA total of 123 chemical constituents were identified， including 33 flavonoids， 26 glycosides， 18 organic acids， 11 terpenoids， 7 phenylpropanoids， 4 gingerol， 3 alkaloids， 3 amino acids， 2 amides and 16 other compounds. ConclusionThe established method can quickly and accurately characterize the chemical components in the reference sample of Huangqi Guizhi Wuwutang （lyophilized powder）， which can provide a basis for the selection of quality evaluation indicators of this formula， and provide a reference for its preparation research.

Views on Key Technical Problems in Research and Development of Famous Classical Formulas / 中国实验方剂学杂志

In this paper， the key technical problems in the research and development of famous classical formulas are analyzed. Firstly， the puzzled problem for a long-time， which is conversion relationship from medicinal metrology of Han dynasty （HD） to that of modern （gram，g）， is comprehensively expounded that one Liang （两） of HD=3 g is more appropriate. Secondly， the model and principles of quality consistency evaluation are given for the transformation from the quality of authoritative basic sample prepared by casserole （ABS-C） to the quality consistency in Laboratory process， pilot-scale process and industrial production. The consistency evaluation model is ξABS-X=K1（Q1ABS-X/Q1ABS-C）+K2（Q2ABS-X/Q2ABS-C）+……+Ki（QiABS-X/QiABS-C）=∑Ki（QiABS-X/QiABS-C）（i=1，2，3……n）. In the formula， ABS-X means laboratory reference sample ABS-C （ABS-L）， pilot-scale ABS-C （ABS-mP） or industrial production ABS-C （ABS-P）， ξABS-X means the quality consistency rate or similarity degree of ABS-L， ABS-mP and ABS-P processes with ABS-C， Ki means the weight of each quality evaluation index （i）， QiABS-X is the data of i in ABS-L， ABS-mP， ABS-P samples， and QiABS-C is the data （or mean） of i in ABS-C sample. Thirdly， in order to control the quality of the herbal medicines whose active ingredients were unknown， their chemical constituents should be studied deeply， and if necessary， the bioassay research should be carried out according to the main efficacy or indication of famous classical formulas. Finally， for the special processing of some herbal medicines， it is difficult to formulate the processing method， technology and standard of prepared slices. It is suggested that the scientific connotation and historical evolution of the special processing method should be thoroughly sorted out， and its technological characteristics are summarized， the modern processing technology and production processes are simulated， and then the corresponding processing methods and quality standards are formulated.

The Ratón Pérez collection: Modern deciduous human teeth at the Centro Nacional de Investigación sobre la Evolución Humana (Burgos, Spain).

OBJECTIVES: The aim of this report is to present the large deciduous tooth collection of identified children that is housed at the National Research Center on Human Evolution (CENIEH) in Burgos, Spain. METHODS: Yearly, members of the Dental Anthropology Group of the CENIEH are in charge of collecting the teeth and registering all the relevant information from the donors at the time of collection. In compliance with Spanish Law 14/2007 of July 3, 2007, on Biomedical Research (BOE-A-2007-12945), all individuals are guaranteed anonymity and confidentiality. When the donor hands in the tooth, they fill out a Donor Information Form and sign the Informed Consent Form. At the same time, another person completes the data label for the transparent polyethylene zip lock bag where the tooth is temporarily stored. All teeth are then transferred to the CENIEH Restoration lab, where the specialists apply the same protocol as for the fossil remains. RESULTS: Although the sample is still growing, from the first collection campaign in 2014 to date it comprises 2977 teeth of children whose ages of tooth loss are between 2 and 15 years. Each tooth is associated with basic information of the individuals and their parents and grandparents (sex, date, and place of birth, ancestry, country of residence), as well as important data about early life history (pregnancy duration, breastfeeding, bottle-feeding) and other relevant information provided by the donors (such as if they are twins, dental loss, or dental extraction). CONCLUSIONS: Due to the scarcity of deciduous dental samples available, the Ratón Pérez collection represents a highly valuable sample for a wide range of disciplines such as forensic, dental, and anthropological fields among others.

Your assay has changed - is it still 'fit for purpose'? What evaluation is required.

A reliable laboratory assay is an essential tool for the diagnosis or surveillance of most animal diseases. Before routine use, assays should be appropriately validated to ensure that they have performance characteristics that provide reliable results and can be used for the intended purpose. It is inevitable that, over time, changes will need to be made to assay reagents, to the assay format, to test a different species or for implementation in a new laboratory. Whenever there is a change (whether it be components, application or location), it is essential to establish whether the new circumstances affect the biological basis and properties of the assay. If the modifications do not affect the biological basis of the assay, the changes might be considered minor and a verification study can be conducted to confirm that the performance characteristics have not been adversely affected. Major changes require a new validation to be carried out. A method comparability study, where original and modified assays are run concurrently to test the same sample panel, provides an extremely robust comparison. However, comparability studies are not always an option, especially for the introduction of a method to a new laboratory. Access to original validation data and suitable reference sample panels then becomes essential to provide evidence that the assay remains 'fit for the intended purpose'.

Les essais de laboratoire fiables constituent des outils essentiels pour le diagnostic ou la surveillance d'une majorité de maladies animales. Avant d'être utilisés en routine, les essais doivent faire l'objet d'une validation appropriée, destinée à s'assurer qu'ils possèdent les caractéristiques de performance nécessaires pour générer des résultats fiables et à déterminer qu'ils peuvent être utilisés pour la finalité prévue. Au fil du temps, il est inévitable que certains changements soient apportés aux réactifs de l'essai ou à son format, visant par exemple à appliquer le test sur autre espèce animale ou dans un nouveau laboratoire. À chaque changement introduit (qu'il s'agisse d'une composante du test, de sa modalité d'application ou du lieu où il est conduit), il est essentiel de déterminer si ces nouvelles circonstances affectent la base biologique et les propriétés de l'essai. Si les modifications n'affectent pas la base biologique de l'essai, les changements peuvent être considérés comme mineurs et une étude de contrôle des performances pourra être réalisée pour confirmer que les caractéristiques de performance n'ont pas subi d'altération indésirable. En cas de changement majeur, une nouvelle étude de validation devra être réalisée. L'étude de comparabilité de méthodes, qui consiste à réaliser simultanément l'essai original et l'essai modifié sur un même panel d'échantillons fournit une comparaison extrêmement robuste. Néanmoins, dans certaines situations les études de comparabilité ne sont pas une option, notamment lorsqu'il s'agit d'introduire la méthode modifiée dans un nouveau laboratoire. Il devient alors indispensable de pouvoir accéder aux données de validation originales et de disposer de panels d'échantillons de référence appropriés afin de fournir la preuve que l'essai est toujours « apte à l'emploi ¼ qui lui a été assigné.

Un ensayo de laboratorio fiable es una herramienta básica para el diagnóstico o la vigilancia de la mayoría de las enfermedades animales. Antes de poder emplear de forma sistemática un ensayo es preciso validarlo debidamente, para tener la seguridad de que presente características de rendimiento adecuadas, que deparen resultados fiables, y de que se ajuste al propósito previsto. Con el tiempo, inevitablemente, será preciso modificar los reactivos y el formato del ensayo, con objeto de aplicarlo a una especie diferente o de practicarlo en un nuevo laboratorio. Siempre que haya un cambio en el ensayo (ya sea en sus componentes o en su modo o lugar de aplicación), será esencial determinar si las nuevas circunstancias influyen en su base biológica o en sus propiedades. Cuando las modificaciones no incidan en su base biológica, se podrá considerar que los cambios son de importancia menor y se podrá realizar un estudio de verificación para comprobar que las características de rendimiento no se han visto negativamente afectadas. Los cambios de mayor entidad exigen un nuevo proceso de validación. Los estudios de comparación de métodos, en los que paralelamente se aplican la técnica original y la modificada a un mismo panel de muestras, deparan una comparación sumamente robusta. Sin embargo, los estudios de comparabilidad no siempre son una posibilidad factible, sobre todo cuando se trata de empezar a aplicar un método en un nuevo laboratorio. En tales casos resultará fundamental tener acceso a los datos de validación originales y a paneles adecuados de muestras de referencia para asegurarse de que el ensayo siga siendo 'idóneo para el propósito previsto'.

Comparative Study of NAP-XPS and Cryo-XPS for the Investigation of Surface Chemistry of the Bacterial Cell-Envelope.

Bacteria generally interact with the environment via processes involving their cell-envelope. Thus, techniques that may shed light on their surface chemistry are attractive tools for providing an understanding of bacterial interactions. One of these tools is Al Kα-excited photoelectron spectroscopy (XPS) with its estimated information depth of <10 nm. XPS-analyses of bacteria have been performed for several decades on freeze-dried specimens in order to be compatible with the vacuum in the analysis chamber of the spectrometer. A limitation of these studies has been that the freeze-drying method may collapse cell structure as well as introduce surface contaminants. However, recent developments in XPS allow for analysis of biological samples at near ambient pressure (NAP-XPS) or as frozen hydrated specimens (cryo-XPS) in vacuum. In this work, we have analyzed bacterial samples from a reference strain of the Gram-negative bacterium Pseudomonas fluorescens using both techniques. We compare the results obtained and, in general, observe good agreement between the two techniques. Furthermore, we discuss advantages and disadvantages with the two analysis approaches and the output data they provide. XPS reference data from the bacterial strain are provided, and we propose that planktonic cells of this strain (DSM 50090) are used as a reference material for surface chemical analysis of bacterial systems.

Progress in Traceable Nanoscale Capacitance Measurements Using Scanning Microwave Microscopy.

Reference samples are commonly used for the calibration and quantification of nanoscale electrical measurements of capacitances and dielectric constants in scanning microwave microscopy (SMM) and similar techniques. However, the traceability of these calibration samples is not established. In this work, we present a detailed investigation of most possible error sources that affect the uncertainty of capacitance measurements on the reference calibration samples. We establish a comprehensive uncertainty budget leading to a combined uncertainty of 3% in relative value (uncertainty given at one standard deviation) for capacitances ranging from 0.2 fF to 10 fF. This uncertainty level can be achieved even with the use of unshielded probes. We show that the weights of uncertainty sources vary with the values and dimensions of measured capacitances. Our work offers improvements on the classical calibration methods known in SMM and suggests possible new designs of reference standards for capacitance and dielectric traceable measurements. Experimental measurements are supported by numerical calculations of capacitances to reveal further paths for even higher improvements.

Analysis of Specific Chromatogram of Wenjingtang Reference Sample / 中国实验方剂学杂志

Objective:To control the quality of the reference sample of Wenjingtang by establishing the specific chromatograms. Method:On the basis of analyzing 15 batches of Wenjingtang freeze-dried powder samples， a high performance liquid chromatography （HPLC） specific chromatogram analysis method of Wenjingtang was established. The system adaptability was investigated and the retention time， relative retention value and deviation caused by different chromatographic columns and instruments were calculated by using the same brand of chromatographic columns， four different brands of chromatographic columns and instruments from three different manufacturers. The precision， repeatability and stability of this method was further completed. The possible chemical components of the freeze-dried powders were speculated and identified by ultra-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry （UPLC-Q-TOF-MS<italic>ⁿ</italic>）. Chromatographic separation was performed on ACQUITY UPLC BEH C₁₈ column （2.1 mm×100 mm， 1.7 μm） with acetonitrile （A）-0.1% formic acid aqueous solution （B） as mobile phase for gradient elution （0-2.8 min， 10%A； 2.8-8.0 min， 10%-18%A； 8.0-12.2 min， 18%-25%A； 12.2-15.3 min， 25%-40%A； 15.3-17.4 min， 40%A； 17.4-20.5 min， 40%-90%A）， and column temperature was set at 30 ℃ with flow rate of 0.4 mL·min^-1. Mass spectrometry was performed on electrospray ionization， data were collected under positive and negative ion modes， and the detection range was <italic>m</italic>/<italic>z</italic> 50-1 600. Result:Ten characteristic peaks were selected as the distinguishing features in this specific chromatograms， and eight of them were identified by comparing with the reference standards， including paeoniflorin （peak 1）， liquiritin apioside （peak 2）， liquiritin （peak 3）， ferulic acid （peak 4）， iquiritigenin （peak 6）， cinnamaldehyde （peak 8）， paeonol （peak 9）and glycyrrhizic acid （peak 10）. By mass spectrometry analysis， 30 compounds were identified， and the source of medicinal materials were assigned. It mainly contained triterpenoid saponins and flavonoids from Glycyrrhizae Radix et Rhizoma， ginsenosides from Ginseng Radix et Rhizoma， monoterpenoid glycosides and tannins from Paeoniae Radix Alba， steroids in Achyranthis Bidentatae Radix， phenolic acids in Angelicae Sinensis Radix. Conclusion:The established characteristic chromatographic analysis method of Wenjingtang is simple， stable and repeatable. The chemical composition of the freeze-dried powder of Wenjingtang is basically defined by mass spectrometry identification and source attribution， which can provide reference for the development and quality control of Wenjingtang in the future.

Determination of trace rare earth elements in rock samples including meteorites by ICP-MS coupled with isotope dilution and comparison methods.

Combining isotope dilution mass spectrometry with a calibration method and choosing appropriate internal standard elements, 14 lanthanides (rare earth elements, REEs) were precisely and accurately determined for rock samples by using quadruple ICP-MS instruments. An enriched spike of 149Sm was used to determine Sm content by an isotope dilution method. Simultaneously, Sm content was determined by a calibration method and the ratio of the two Sm values was used for correcting the preparation loss of the other REEs, which were analyzed only by a calibration method. Indium and Tl were chosen for use as internal standard elements. Applying the procedure developed in this study to the homogenized Allende meteorite powder sample prepared by the Smithsonian Institution, Washington, D. C., US and several geological reference samples issued by the Geological Survey of Japan and the US geological Survey, precision and accuracy of the data obtained were evaluated and the accuracy was found to be equivalent to isotope dilution values obtained by thermal ionization mass spectrometry. Rare earth element concentrations in several meteorite samples were determined, and results indicate that our procedure is appropriate for a wide variety of whole rock compositions.

How should we diagnose disease in palaeopathology? Some epistemological considerations.

This paper analyses some of the epistemological frameworks that underpin diagnosis in palaeopathology. Currently, the dominant approach is comparative: relationships between skeletal lesions and disease in a reference group in which there is independent evidence of the diseases present in individuals are used to identify disease in unknown archaeological skeletons on the basis of the lesions present. This is essentially a reference sample - target sample approach, analogous to that used to develop methodology in other areas of biological anthropology (e.g. age estimation in palaeodemography). As well as considerable strengths, this approach also has significant weaknesses. Many of these arise from the nature of the reference material (mainly pathology museum and other skeletal collections, and published collations of medical imaging data) used to develop diagnostic criteria. There may also be a tendency toward over-emphasis on pattern-matching between reference and target material, and an under-emphasis on developing our understanding of the biology of bone lesions. Despite its shortcomings, the comparative approach is likely to remain the foundation of most palaeopathological work, but we should increasingly augment it with other diagnostic approaches, especially those grounded in the pathophysiology of bony responses to disease.