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Background: The currently used methods for the detection of methylene tetrahydrofolic acid reductase (MTHFR) C677T single nucleotide polymorphism (SNP) are either time-consuming or expensive. In this study, we devised an accurate, rapid and easy-to-use SNP detection system based on fluorescent primers amplification refractory mutation system qPCR, known as FP ARMS-qPCR. Methods: Fluorescent primers (FPs) modified by fluorescent dye or quencher near the 3′ terminal thymine were designed. The reaction conditions were optimized and the performance was evaluated. Using commercial kits as controls, 242 samples were tested in parallel to verify the feasibility of the FP ARMS-qPCR assay. Results: We demonstrated the good sensitivity and specificity of the FP ARMS-qPCR with optimized conditions. The assay was able to accurately distinguish between different SNP sites of MTHFR C677T in less than 2 h using as low as 50 pg of template genomic DNA. Completely consistent genotyping results reveal that FP ARMS-qPCR is concordant with commercial kits. Conclusion: We established a specific, sensitive, and rapid FP ARMS-qPCR method for the detection of MTHFR C677T genotype. This could also serve as a potential diagnostic tool for a variety of diseases. [ABSTRACT FROM AUTHOR]

Background: Multiple fluorescence PCR was used to facilitate the low cost detection of such infectious pathogens. The melting curve combined with the fluorescence PCR method was used to detect more targets. The characteristic melting peaks of the melting curve formed by the melting probe were complementary to the fluorescent probes and more targets could be identified by the different melting peaks in one fluorescence channel. Results: The most optimal conditions were confirmed by optimizing the experimental conditions, such as the concentration of fluorescent probes and the melting probe, which is crucial for forming the characteristic melting peaks. LOD, multiplex performance and sample detection performance were evaluated separately. According to the results, the LOD of all targets was as low as five or ten copies/tube, excepting for Zaire type Ebola virus, whose LOD is 25 copies/tube. The method could simultaneously detected more targets, even up to eight bacteria or nine viruses and the result was accurate. In 173 clinical or real-world samples, the result was in keeping with the expected or clinical results, excepting for one case of the soil sample, and the consistency rate of the detection results reached 99.42%. Significance: We achieved a novel method for multiple detection of up to 17 highly infectious pathogenic microorganisms and performed well in real sample detection, and the results were consistent with the expected or clinical results. We provided a new detection tool for disease prevention, control centers and clinical practice.

High-temperature equations of state (EoSs) for solid magnesium with hexagonal close-packing (hcp) and for liquid magnesium were formulated herein by using experimental data on the thermodynamic properties, thermal expansion, compressibility, temperature-dependent bulk compression modulus, and melting curve. The totality of experimental data was co-optimized using the temperature-dependent Tait EoS over a pressure range of 0–500 kbar at temperatures of 20–923 K for solid Mg and at 923–2000 K for liquid Mg. The temperature dependence of thermodynamic and thermophysical parameters was described by the extended Einstein model. The resultant EoSs give a good fit to the whole set of experimental data within measurement errors of individual quantities. The high prediction accuracy was achieved by estimating the thermodynamic and thermophysical properties of solid Mg. For liquid Mg, the suggested model adequately describes and, in some cases, averages the existing experimental data. [ABSTRACT FROM AUTHOR]

PIK3CA mutations have important therapeutic and prognostic implications in various cancer types. However, highly sensitive detection of PIK3CA hotspot mutations in heterogeneous tumor samples remains a challenge in clinical settings. To establish a rapid PCR assay for highly sensitive detection of multiple PIK3CA hotspot mutations. We described a novel melting curve analysis-based assay using looping-out probes that can enrich target mutations in the background of excess wild-type and concurrently reveal the presence of mutations. The analytical and clinical performance of the assay were evaluated. The developed assay could detect 10 PIK3CA hotspot mutations at a mutant allele fraction of 0.05–0.5% within 2 h in a single step. Analysis of 82 breast cancer tissue samples revealed 43 samples with PIK3CA mutations, 28 of which were confirmed by Sanger sequencing. Further testing of 175 colorectal cancer tissue samples showed that 24 samples contained PIK3CA mutations and 19 samples were confirmed by Sanger sequencing. Droplet digital PCR supported that all mutation-containing samples undetected by sequencing contained mutations with a low allele fraction. The rapidity, ease of use, high sensitivity and accuracy make the new assay a potential screening tool for PIK3CA mutations in clinical laboratories. [ABSTRACT FROM AUTHOR]

Deyong Tan,1– 4 Jianfeng Han,5 Qingzhi Sun,5 Xing Cheng,5 Juan Liu,5 Jia Liu,5 Qing Li,1– 4 Lizhong Dai5 1Department of Clinical Pharmacology, Xiangya Hospital, Central South University, Changsha, 410008 People’s Republic of China; 2Institute of Clinical Pharmacology, Central South University, Hunan Key Laboratory of Pharmacogenetics, Changsha, 410078 People’s Republic of China; 3Engineering Research Center of Applied Technology of Pharmacogenomics, Ministry of Education, Changsha, 410078 People’s Republic of China; 4National Clinical Research Center for Geriatric Disorders, Changsha, Hunan, 410008 People’s Republic of China; 5Sansure Biotech Inc, Changsha, Hunan Province, People’s Republic of ChinaCorrespondence: Qing Li, Department of Clinical Pharmacology, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, Hunan, People’s Republic of China, Tel +86 731 84805380, Fax +86 731-82354476, Email liqing9251026@csu.edu.cn Lizhong Dai, Sansure Biotech Inc, No. 680 Lusong Road, Changsha, Hunan, People’s Republic of China, Tel +86 73188883176, Email lizhongd@sansure.com.cnObjective: In this study, we conducted a multi-center research on six common lower respiratory tract pathogens using novel multiplex fluorescence quantitative polymerase chain reaction (PCR), and investigated the additional diagnostic value of this method, to provide a molecular diagnostic basis for clinical practice.Methods: From March 2019 to October 2021, a total of 2047 respiratory sputum samples were collected from Hunan Provincial People’s Hospital (the First Affiliated Hospital of Hunan Normal University), Hunan Provincial Children’s Hospital, Jiangxi Provincial Children’s Hospital, and Wuhan Infectious Disease Hospital. The samples were analyzed using a novel multiplex fluorescence quantitative PCR method for Klebsiella pneumoniae, Streptococcus pneumoniae, Haemophilus influenzae, Pseudomonas aeruginosa, Legionella pneumophila, and Staphylococcus aureus. The results were compared to the results of bacterial culture and sequencing, as well as the results of third-party kits.Results: Compared to the bacterial culture method, 2047 samples were detected with a sensitivity of 100%, a specificity of 72.22%, and an overall compliance rate of 81.91%. Compared to the sequencing method, the positive agreement percentage was 99.88%, the negative agreement percentage was 97.72%, and the overall agreement rate was 98.84%. Compared to similar control reagents, the positive agreement percentage was 100%, negative agreement percentage was 79.79%, and overall compliance rate was 96.19%.Conclusion: The multiplex fluorescence PCR method has the advantages of simultaneously detecting multiple pathogenic bacteria and reducing the duration of pathogen culture identification. Combined detection can increase the detection rate, which has favorable performance and application prospects.Keywords: bacterial infection, lower respiratory tract, melting curve, multiplex PCR, rapid diagnosis

This work aims to adopt a simple modulus prediction method for the crystalline poly(ethylene-terephthalate) (PET), which has strong cold-crystallization ability. Based on a single melting curve generated by calorimetry, crystallinity and average melting temperature can easily be evaluated and consequently, tensile modulus can be predicted. Nonetheless, in the case of polymers with cold crystallization behavior, such as PET, the melting process is affected by cold crystallization, impeding the simple calculation of the aforementioned important parameters. In this paper, the techniques to eradicate cold crystallization during calorimetry are presented. Accordingly, the results of a tensile modulus prediction model are presented and discussed. The crystallization and melting characteristics of PET were measured by differential scanning calorimetry (DSC). The mechanical properties of the specimens were estimated by standardized tensile tests. The specimens, which were used for mechanical tests were fabricated using conventional injection molding. The samples were annealed at different temperatures in order to obtain different crystalline structures. The results clearly indicate that the prediction technique is capable to describe the tensile modulus of PET accurately in the case of very diverse crystalline structures.

The melting line of cobalt has been investigated both experimentally, using synchrotron X-ray diffraction coupled with laser-heated diamond anvil cells, and theoretically, using ab initio simulations. Over the investigated pressure and temperature range – between 30 and 100 GPa and from ambient temperature up to 4000 K – the hexagonal close-packed structure, stable at ambient conditions, is replaced at high temperature by the face-centered cubic structure, observed stable till melting. The melting temperatures obtained by the two methods are in remarkable agreement and the melting line can be well described by a Simon–Glatzel equation of the form Tm = 1768(K)(P(GPa)/35.62+1)0.64. Finally, from the obtained results it was possible to determine a thermal equation of state for the cubic face-centered phase of Co.

High-temperature equations of state (EoS) for solid and liquid silver were constructed using experimental data on the thermodynamic properties, thermal expansion, compressibility, bulk compression modulus and sound velocity, supplemented with the phase diagram data (melting curve). The totality of experimental data was optimized using the temperature-dependent Tait equation over a pressure range of up to ~ 1000 kbar and over a temperature range from 20 K to the melting point for solid silver and to 4400 K for liquid silver. The temperature dependence of thermodynamic and thermophysical parameters for solid silver was described by an extended Einstein model. For liquid silver, the heat capacity was assumed constant over the specified temperature range, and the temperature dependence of density was described by a quadratic relationship. The isothermal bulk modulus and its pressure derivative were estimated by the Tait equation to be 1083.9 kbar, 5.8704 (for solid silver) and 809.84 kbar, 7.7044 (for liquid silver). The obtained values suggest a considerably greater compressibility of the liquid phase. The derived Tait EoS for the solid and liquid phases gives a good fit to the whole set of available experimental data within the measurement error of individual parameters. [ABSTRACT FROM AUTHOR]

We present the analytic forms of the principal Hugoniots of actinium (Ac) and the lanthanide promethium (Pm), which have both never been measured or calculated before, as well as those of terbium (Tb), thulium (Tm), and lutetium (Lu), the three least studied of the remaining lanthanides. They are based on our new analytic model of principal Hugoniot. A comparison of the five Hugoniots to our own independent theoretical calculations demonstrates very good agreement in every case, but each of the Hugoniots of Tb, Tm, and Ac from the TEFIS database, which ours are also compared to, appear to violate Johnson's theoretical constraint 4 < η max < 7 for the maximum compression ratio η max , which corresponds to the Hugoniot turnaround point. Possible reason for this behavior of the TEFIS Hugoniots is briefly discussed. [ABSTRACT FROM AUTHOR]

The pressure–temperature scales in DAC and shock wave (SW) experiments should be corrected by taking into account the thermal pressure shifts. In the present contribution, it is further claimed that first-principle ab initio DFT and MD simulations should serve as an anchor for correcting the pressures and temperatures reported by DAC and SW experiments. It was concluded that upon deriving the actual pressure sensed by the explored sample, the thermal pressure and the temperature shifts must be taken into account when constructing melting curves. Therefore, melting curves measured by diamond anvil cells for 3d elements do not contribute to a better understanding of the geophysical Earth's inner core. In addition, the advantage of the Lindemann–Gilvarry vs. Simon–Glatzel fitting procedure of melting curves is shown. [ABSTRACT FROM AUTHOR]

Mixed oxides of uranium and plutonium (MOX) are currently considered as a reference fuel for the new generation of fast breeder reactors such as ASTRID. The key factor determining the performance and safety of a fuel such as MOX is its operational limits in the application environment which are closely related to the material's structure and thermodynamic stability. They are in turn closely related to the ambient (zero pressure) melting point  (T m) ; thus,  T m  is an important engineering parameter. Furthermore, PuO 2  and UO 2  are two endpoints of the phase diagram of MOX; therefore, their ambient  T m s are fundamental reference points. However, the current knowledge of the  T m  of MOX is limited and controversial as several studies available in the literature do not converge on the unique behavior of  T m  as a function of  x.  Specifically, some studies produced  T m  as a monotonically decreasing function of x such that, with  T m  of UO 2 (x = 0)  of 3150 K,  T m  of PuO 2 (x = 1)  is ∼2650 K, while other studies resulted in  T m  having a local minimum at  0.5 < x < 1  such that  T m  of PuO 2  is ∼3000 K, so that the difference between the two values of  T m  is as high as 350 K. In this study, using the ab initio Z method implemented with the Vienna Ab Initio Simulation Package (VASP), we carry out a suite of quantum molecular dynamics simulations to obtain the ambient  T m  of MOX at several values of  x ,   0 < x < 1 ,  including the two end points  (x = 0 ,   x = 1).  Our results agree with the behavior of  T m  of MOX as a function of x having a local minimum at  x = 0.7  and  T m  of PuO 2  of 3050 K. Our study suggests potential ambient density–melting point systematics of MOX which may be useful in subsequent research on MOX such as its thermoelasticity modeling. [ABSTRACT FROM AUTHOR]

Copyright of Proceedings of the YSU B: Chemical & Biological Sciences / Gitakan Teghekagir. K'imia, Kensabanut'yun is the property of Publishing House of Yerevan State University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This work presents a robustness study of a previously developed empirical model that links Young's modulus to two key parameters of crystalline structure; crystallinity and lamellae thickness. The reliability of this modulus prediction model was tested by using different calorimeters and different polypropylene grades as well. Small samples were fabricated from injection-molded bars from different locations of the specimens in order to check the effect of structural inhomogeneity originated by the dynamic processing conditions. In addition, the standard deviation and consequently the accuracy of the prediction was tested by repeated calorimetric measurements. The crystalline structure and melting characteristics were measured by differential scanning calorimetry (DSC). The tensile properties of studied specimens were evaluated by standardized tensile tests. Although, the accuracy and reliability of the prediction model is dependent on the instrument used for thermal analysis, reasonably good agreement was found between the predicted and measured values in most cases. However, we may note that only well-calibrated calorimeters are suitable for reliable prediction of the modulus. [ABSTRACT FROM AUTHOR]

High-temperature equations of state for solid and liquid copper were constructed herein using experimental data on thermodynamic properties, thermal expansion, compressibility, bulk modulus and sound velocity measurements, supplemented with phase diagram data (melting curve). The totality of experimental data were optimized using the temperature-dependent Tait equation over a pressure range of up to 1000 kbar and over a temperature range from 20 K to the melting point for solid copper and to 3900 K for liquid copper. The temperature-dependence of thermodynamic and thermophysical parameters was described by an expanded Einstein model. The resultant equations of state describe well the entire set of experimental data within measurement errors of individual parameters. [ABSTRACT FROM AUTHOR]

Abstract Background The study describes the application of the multiplex high-resolution melting curve (MHRM) assay for the simultaneous detection of five common bacterial pathogens (Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii and Escherichia coli) directly from bronchoalveolar lavage samples. Results Our MHRM assay successfully identified all five respiratory pathogens in less than 5 h, with five separate melting curves with specific melt peak temperatures (Tm). The different Tm were characterized by peaks of 78.1 ± 0.4 °C for S. aureus, 83.3 ± 0.1 °C for A. baumannii, 86.7 ± 0.2 °C for E. coli, 90.5 ± 0.1 °C for K. pneumoniae, 94.5 ± 0.2 °C for P. aeruginosa. The overall sensitivity and specificity of MHRM were 100% and 88.8–100%, respectively. Conclusions Our MHRM assay offers a simple and fast alternative to culture approach for simultaneous detection of five major bacterial lower respiratory tract infection pathogens. Utilization of this assay can help clinicians initiate prompt and appropriate antimicrobial treatment, towards reducing the morbidity and mortality of severe respiratory infections.

The diagnosis of urinary tract infections (UTIs) is usually based on the results of urine culture, but it is time-consuming, labor-intensive and has a low sensitivity. The aim of this study was to develop multiplex high-resolution melting assay (MHRM) for the simultaneous detection of five common bacterial pathogens (Escherichia coli, Klebsiella pneumoniae, Staphylococcus saprophyticus, Enterococcus faecalis, and group B streptococci (GBS)) directly from urine samples. A total of 287 urine specimens were evaluated by HRM assay and the results were compared with the conventional culture method. Five different melt curves generated and differentiated five bacterial pathogens. The detection limit of the MHRM assay was 1.5 × 103CFU/ml for E. coli and K. pneumoniae and 1.5 × 102CFU/ml for S. saprophyticus, E. faecalis and GBS. Compared to culture, the specificity of the MHRM assay ranged from 99.3 to 100%, and sensitivity 100% for all test pathogens. The MHRM assay developed in the current study might be functional tool for the diagnosis of UTIs and has the potential for direct detection of the organism in the clinical samples. Additionally, it creates results in less than 5 h, helping clinicians to start treatment with appropriate antimicrobial agents. This method could be a useful supplement to urine culture. [ABSTRACT FROM AUTHOR]

Quantum melting is the phenomenon of cold (zero-temperature) melting of a pressure-ionized substance which represents a lattice of bare ions immersed in the background of free electrons, i.e., the so-called one-component plasma (OCP). It occurs when the compression of the substance corresponds to the zero-point fluctuations of its ions being so large that the ionic ordered state can no longer exist. Quantum melting corresponds to the classical melting curve reaching a turnaround point beyond which it starts going down and eventually terminates, when zero temperature is reached, at some critical density. This phenomenon, as well as the opposite phenomenon of quantum crystallization, may occur in dense stellar objects such as white dwarfs, and may play an important role in their evolution that requires a reliable thermoelasticity model for proper physical description. Here we suggest a modification of our unified analytic melt-shear thermoelasticity model in the region of quantum melting, and derive the corresponding Grüneisen parameters. We demonstrate how the new functional form for the cold shear modulus can be combined with a known equation of state. One of the constituents of the new model is the melting curve of OCP crystal which we also present. The inclusion of quantum melting implies that the modified model becomes applicable in the entire density range of the existence of the solid state, up to the critical density of quantum melting above which the solid state does not exist. Our approach can be generalized to model melting curves and cold shear moduli of different solid phases of a multi-phase material over the corresponding ranges of mechanical stability. [ABSTRACT FROM AUTHOR]

Soil microorganisms play an essential role in biogeochemical cycles. One approach to study these microbial communities is quantifying functional genes by quantitative PCR (qPCR), in which a melting curve analysis is usually assessed to confirm that a single PCR product is being quantified. However, the high diversity of functional genes in environmental samples could generate more than one peak in those curves, so the presence of two or multiple peaks does not always indicate nonspecific amplification. Here, we analyzed the taxonomic diversity of soil microorganisms harboring functional genes involved in nitrogen (N) and phosphorus (P) cycles, based on a database of genomes and metagenomes, and predicted the melting curve profiles of these genes. These functional genes were spread across many bacterial phyla, but mainly Proteobacteria and Actinobacteria. In general, the melting curves exhibited more than one peak or peaks with shoulders, mainly related to the variation of the nucleotide composition of the genes and the expected size of the amplicons. These results indicate that the melting curves of functional genes from environmental samples should be carefully evaluated, being in silico analyses a cost-effective way to identify inherent sequence diversity and avoid interpreting multiple peaks always as unspecific amplifications. [ABSTRACT FROM AUTHOR]

Abstract Background One of the parameters required for the assessment of food and feed safety is detection and identification of genetically modified organisms. Legislation in some countries necessitates detection and quantification of modification in food and feed samples. Scientists have raised concern about safety of antibiotic resistance marker (ARM) genes used for transformation of crops intended for human and animal consumption. In the present work two molecular approaches have been adopted: one exploratory; for detection and quantification of ARM genes in tested plant samples and the other confirmatory; to determine the specificity/reliability of the obtained results. Results Results revealed that primers for neomycin phosphotransferase (nptII) and aminoglycoside 3″ adenyl-transferase (aadA) were amplified in the majority of the 36 DNA screened samples. Melting curve analysis using hygromycin phosphotransferase (aphIV) gene as target sequence for the fluorescent-based detection approach was performed to ensure reliability and specificity of this procedure and to confirm results obtained by using conventional polymerase chain reaction (PCR). Quantitative RT-PCR results and validation analysis followed, revealed that all of the tested DNA samples were not violating the European legislation for GMOs labeling (0.9%). Conclusions The results fully demonstrated the reproducibility, sensitivity/specificity of the adopted approaches for detection and quantification of even traces of GMO contents. Applying measurement uncertainty (MU) procedures presented in this work will help decision makers to ensure compliance with International Legislation and Regulations. This in its turn will facilitate and enhance trading with countries having compelling labeling regulations.

The diagnosis of urinary tract infections (UTIs) is usually based on the results of urine culture, but it is time-consuming, labor-intensive and has a low sensitivity. The aim of this study was to develop multiplex high-resolution melting assay (MHRM) for the simultaneous detection of five common bacterial pathogens (Escherichia coli, Klebsiella pneumoniae, Staphylococcus saprophyticus, Enterococcus faecalis, and group B streptococci (GBS)) directly from urine samples. A total of 287 urine specimens were evaluated by HRM assay and the results were compared with the conventional culture method. Five different melt curves generated and differentiated five bacterial pathogens. The detection limit of the MHRM assay was 1.5 × 103 CFU/ml for E. coli and K. pneumoniae and 1.5 × 102 CFU/ml for S. saprophyticus, E. faecalis and GBS. Compared to culture, the specificity of the MHRM assay ranged from 99.3 to 100%, and sensitivity 100% for all test pathogens. The MHRM assay developed in the current study might be functional tool for the diagnosis of UTIs and has the potential for direct detection of the organism in the clinical samples. Additionally, it creates results in less than 5 h, helping clinicians to start treatment with appropriate antimicrobial agents. This method could be a useful supplement to urine culture.

Conventional PCR methods can detect only a few targets simultaneously and do not fulfill most clinical requirements, especially those for detecting plasma circulating DNA. By designing characteristic universal fluorescent probes, combining multiplex PCR with the invasive reaction, and analyzing the resulting differences in the melting curves formed by extension with double-stranded probes, we developed a new method to distinguish between three mutations in the same fluorescent channel and nine mutations in three fluorescent channels in a single tube. After optimization, this method was used to distinguish between 27 mutations using only three reactions, and mutations representing as low as 0.2%–0.5% of DNA could be detected, even when up to nine mutations were present at the same time. Testing of nine clinical samples, including three L858R-positive, four 19 del-positive, and two L861Q-positive samples, showed consistent results with digital PCR tests. Compared with the conventional PCR method, our method expands the capabilities of fluorescence detection by achieving multiplex detection in a single-tube, thereby providing a simple, low-cost tool for clinical applications.

We present the analytic forms of the principal Hugoniots of actinium (Ac) and the lanthanide promethium (Pm), which have both never been measured or calculated before, as well as those of terbium (Tb), thulium (Tm), and lutetium (Lu), the three least studied of the remaining lanthanides. They are based on our new analytic model of principal Hugoniot. A comparison of the five Hugoniots to our own independent theoretical calculations demonstrates very good agreement in every case, but each of the Hugoniots of Tb, Tm, and Ac from the TEFIS database, which ours are also compared to, appear to violate Johnson’s theoretical constraint 4<ηmax<7 for the maximum compression ratio ηmax, which corresponds to the Hugoniot turnaround point. Possible reason for this behavior of the TEFIS Hugoniots is briefly discussed.

The pressure–temperature scales in DAC and shock wave (SW) experiments should be corrected by taking into account the thermal pressure shifts. In the present contribution, it is further claimed that first-principle ab initio DFT and MD simulations should serve as an anchor for correcting the pressures and temperatures reported by DAC and SW experiments. It was concluded that upon deriving the actual pressure sensed by the explored sample, the thermal pressure and the temperature shifts must be taken into account when constructing melting curves. Therefore, melting curves measured by diamond anvil cells for 3d elements do not contribute to a better understanding of the geophysical Earth’s inner core. In addition, the advantage of the Lindemann–Gilvarry vs. Simon–Glatzel fitting procedure of melting curves is shown.

Chromium possesses remarkable physical properties such as hardness and corrosion resistance. Chromium is also a very important geophysical material as it is assumed that lighter Cr isotopes were dissolved in the Earth's molten core during the planet's formation, which makes Cr one of the main constituents of the Earth's core. Unfortunately, Cr has remained one of the least studied 3 d transition metals. In a very recent combined experimental and theoretical study (Anzellini et al., Scientific Reports, 2022), the equation of state and melting curve of chromium were studied to 150 GPa, and it was determined that the ambient body-centered cubic (bcc) phase of crystalline Cr remains stable in the whole pressure range considered. However, the importance of the knowledge of the physical properties of Cr, specifically its phase diagram, necessitates further study of Cr to higher pressure. In this work, using a suite of ab initio quantum molecular dynamics (QMD) simulations based on the Z methodology which combines both direct Z method for the simulation of melting curves and inverse Z method for the calculation of solid–solid phase transition boundaries, we obtain the theoretical phase diagram of Cr to 2.5 TPa. We calculate the melting curves of the two solid phases that are present on its phase diagram, namely, the lower-pressure bcc and the higher-pressure hexagonal close-packed (hcp) ones, and obtain the equation for the bcc-hcp solid–solid phase transition boundary. We also obtain the thermal equations of state of both bcc-Cr and hcp-Cr, which are in excellent agreement with both experimental data and QMD simulations. We argue that 2180 K as the value of the ambient melting point of Cr which is offered by several public web resources ("Wikipedia," "WebElements," "It's Elemental," etc.) is most likely incorrect and should be replaced with 2135 K, found in most experimental studies as well as in the present theoretical work. [ABSTRACT FROM AUTHOR]

High-temperature equations of state for solid and liquid aluminum were constructed herein using experimental data on thermodynamic properties, thermal expansion, compressibility, bulk modulus and sound velocity measurements, supplemented with phase diagram data (melting curve). The entire set of experimental data was optimized using the temperature-dependent Tait equation over a pressure range of up to 800 kbar and over a temperature range from 20 K to the melting point for solid aluminum and to 3800 K for liquid aluminum. The temperature dependence of thermodynamic and thermophysical parameters was described by an expanded Einstein model. The resultant equations of state describe well the totality of experimental data within measurement errors of individual variables. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Background The analyses of amplification and melting curves have been shown to provide valuable information on the quality of the individual reactions in quantitative PCR (qPCR) experiments and to result in more reliable and reproducible quantitative results. Implementation The main steps in the amplification curve analysis are (1) a unique baseline subtraction, not using the ground phase cycles, (2) PCR efficiency determination from the exponential phase of the individual reactions, (3) setting a common quantification threshold and (4) calculation of the efficiency-corrected target quantity with the common threshold, efficiency per assay and Cq per reaction. The melting curve analysis encompasses smoothing of the observed fluorescence data, normalization to remove product-independent fluorescence loss, peak calling and assessment of the correct peak by comparing its melting temperature with the known melting temperature of the intended amplification product. Results The LinRegPCR web application provides visualization and analysis of a single qPCR run. The user interface displays the analysis results on the amplification curve analysis and melting curve analysis in tables and graphs in which deviant reactions are highlighted. The annotated results in the tables can be exported for calculation of gene-expression ratios, fold-change between experimental conditions and further statistical analysis. Web-based LinRegPCR addresses two types of users, wet-lab scientists analyzing the amplification and melting curves of their own qPCR experiments and bioinformaticians creating pipelines for analysis of series of qPCR experiments by splitting its functionality into a stand-alone back-end RDML (Real-time PCR Data Markup Language) Python library and several companion applications for data visualization, analysis and interactive access. The use of the RDML data standard enables machine independent storage and exchange of qPCR data and the RDML-Tools assist with the import of qPCR data from the files exported by the qPCR instrument. Conclusions The combined implementation of these analyses in the newly developed web-based LinRegPCR ( https://www.gear-genomics.com/rdml-tools/ ) is platform independent and much faster than the original Windows-based versions of the LinRegPCR program. Moreover, web-based LinRegPCR includes a novel statistical outlier detection and the combination of amplification and melting curve analyses allows direct validation of the amplification product and reporting of reactions that amplify artefacts.

A novel method, termed ladder-shape melting temperature isothermal amplification (LMTIA), was developed in this study. As a proof of concept, one pair of primers or two pairs of nested primers and a thermostable DNA polymerase were employed to amplify the internal transcribed spacer of Oryza sativa with the ladder-shape melting temperature curve. Our results demonstrated that the LMTIA assay with nested primers was 50-fold more sensitive than the LAMP assay with the same level of specificity. The LMTIA method has the potential to be used for the prevention and control of emerging epidemics caused by different types of pathogens.

Aspirin (ASP) is currently the drug of choice for antiplatelet therapy. However, approximately 5%–45 % of patients are resistant to ASP and do not achieve the expected result. At present, a few studies have investigated the correlation between ASP resistance (AR) and single-nucleotide polymorphism (SNP). Traditional detection methods are time-consuming and laborious, affecting the accuracy of personalized medicine. This study aimed to establish a new assay to identify four SNPs associated with AR. A large amount of double-stranded DNA was formed after multiple cycles of specific exponential amplification by ligase chain reaction, the specific melting peak of which was visible in the detection curve, with a detection limit of 10−11mol/L. The specificity experiments of different proportions of wild-type and mutant plasmid standards showed that the novel method could detect up to 1 % allele frequency and the specificity was good. Clinical blood samples of 57 patients were tested in this study. The results were consistent with those of sequencing and more accurate and reliable than those of the high-resolution melting method. The technique used in this study was simple, sensitive and specific compared with the traditional method. Statistical analysis revealed that AR was significantly correlated with the rs12041331 site of the PEAR1 gene and the rs1695 site of the GSTP1 gene, providing an important reference value for the study of AR. [Display omitted] • LCR was successfully constructed to detect four kinds of SNPs related to ASP. • LCR assays are more accurate, simpler, more specific and more practical than HRM. • HRM has higher requirements for the operator than LCR. [ABSTRACT FROM AUTHOR]

Mixed oxides of uranium and plutonium (MOX) are currently considered as a reference fuel for the new generation of fast breeder reactors such as ASTRID. The key factor determining the performance and safety of a fuel such as MOX is its operational limits in the application environment which are closely related to the material’s structure and thermodynamic stability. They are in turn closely related to the ambient (zero pressure) melting point (Tm); thus, Tm is an important engineering parameter. Furthermore, PuO2 and UO2 are two endpoints of the phase diagram of MOX; therefore, their ambient Tms are fundamental reference points. However, the current knowledge of the Tm of MOX is limited and controversial as several studies available in the literature do not converge on the unique behavior of Tm as a function of x. Specifically, some studies produced Tm as a monotonically decreasing function of x such that, with Tm of UO2(x=0) of 3150 K, Tm of PuO2(x=1) is ∼2650 K, while other studies resulted in Tm having a local minimum at 0.5

While hydrogen could be an important light alloying element in planetary iron cores, phase relations in the Fe‐FeH system remain largely unknown at high pressures and temperatures (P‐T). A speculative Fe‐H2 phase diagram has been proposed assuming continuous solid solution between Fe and FeH and eutectic melting between FeH and H2. Recent studies revealed that stoichiometric FeH becomes non‐magnetic above ∼40 GPa, which might affect its melting behavior. Here we examined the melting curve of non‐magnetic FeH between 43 and 152 GPa by a combination of laser‐heated diamond‐anvil cell techniques and synchrotron X‐ray diffraction (XRD) analyses. The melting temperature was determined by employing the appearance of additional hazy XRD signals upon quenching temperature as a melting criterion. We also performed thermodynamic modeling, which well reproduces the change in the curvature of FeH melting curve upon the loss of magnetism and extrapolates the experimental constraints to inner core pressures. The XRD data showed that non‐magnetic FeH melts congruently at temperatures higher than the known eutectic melting curve for FeHx (x > 1). Combined with the fact that the endmembers exhibit different crystal structures, these results indicate that Fe and non‐magnetic FeH form a eutectic system. The dT/dP slope of the FeH melting curve is comparable to that for Fe, suggesting that the eutectic liquid composition of FeH0.42 (Fe + 0.75 wt% H) previously estimated at ∼40 GPa changes little with increasing pressure. Plain Language Summary: It is likely that a large amount of water was transported to the Earth during its accretion and hydrogen was incorporated into core‐forming metals. Indeed, recent calculations found that hydrogen could be an important light element in both the outer and inner core to explain the observed density and velocities. Nevertheless, experimental study of Fe‐H alloys has been challenging, in part because hydrogen is almost insoluble in iron at 1 bar. Here we determined the melting curve of stoichiometric FeH in the non‐magnetic state from 43 to 152 GPa based on X‐ray diffraction (XRD) measurements. The melting temperature of FeH increases rapidly with compression upon the loss of local spin moment. The XRD spectra show that stoichiometric FeH melts congruently, suggesting eutectic melting between Fe and FeH that is supported by the different crystal structures between these two endmembers. Since the dT/dP slopes of the Fe and FeH melting curves are similar, it is likely that the Fe‐FeH eutectic liquid composition is little dependent on pressure and could be around FeH0.42 at inner core conditions, which gives the upper bound for the hydrogen concentration in the outer core. Key Points: We determined the melting curve of non‐magnetic FeH to 152 GPa based on synchrotron X‐ray diffraction (XRD) measurementsXRD data indicated congruent melting of non‐magnetic FeH, suggesting eutectic melting between Fe and FeH above ∼40 GPaSimilar dT/dP slopes between the melting curves of Fe and FeH imply little pressure dependence of the Fe‐FeH eutectic liquid composition [ABSTRACT FROM AUTHOR]

Background: The study describes the application of the multiplex high-resolution melting curve (MHRM) assay for the simultaneous detection of five common bacterial pathogens (Pseudomonas aeruginosa, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii and Escherichia coli) directly from bronchoalveolar lavage samples. Results: Our MHRM assay successfully identified all five respiratory pathogens in less than 5 h, with five separate melting curves with specific melt peak temperatures (Tm). The different Tm were characterized by peaks of 78.1 ± 0.4 °C for S. aureus, 83.3 ± 0.1 °C for A. baumannii, 86.7 ± 0.2 °C for E. coli, 90.5 ± 0.1 °C for K. pneumoniae, 94.5 ± 0.2 °C for P. aeruginosa. The overall sensitivity and specificity of MHRM were 100% and 88.8–100%, respectively. Conclusions: Our MHRM assay offers a simple and fast alternative to culture approach for simultaneous detection of five major bacterial lower respiratory tract infection pathogens. Utilization of this assay can help clinicians initiate prompt and appropriate antimicrobial treatment, towards reducing the morbidity and mortality of severe respiratory infections. [ABSTRACT FROM AUTHOR]

In the present study, a duplex SYBR Green real-time PCR assay was developed in order to indentify Actinobacillus pleuropneumoniae and Haemophilus parasuis infection in one reaction, through a melting curve analysis. This method utilized two pairs of specific primers that allowed the amplification of highly conserved regions of A. pleuropneumoniae Apx IV and H. parasuis omp P2 gene. Reconstitution experiments were conducted by using PMD - 19T plasmid in order to determine the sensitivity of the assay. The results showed that the Tm values of the melting curves of A. pleuropneumoniae and H. parasuis were 83.36±0.09ºC and 76.48±0.17ºC, respectively that could accurately distinguish these two pathogens. And no cross reaction were observed between other respiratory pathogens, which suggested a high specificity of two primers. The detection sensitivity of the assay was 127 and 96 copies/μL which was higher than that of the ordinary PCR detection methods. This rapid technique may present a simple, useful option for simultaneous detection of A. pleuropneumoniae and H. parasuis, which would be feasible and attractive for clinical samples diagnosis and epidemiological investigations.

Equations of state are used for the evaluation of pressure effects on solid (Alkali halides) at room temperature and high temperature up to melting point, Thermodynamic properties such as , of alkali halide (NaCl-B1) at high pressure and room temperature have been evaluated and the results are compared with experimental data and gave good results up to 5 GPa but beyond it the results of these equations of state diverge from experimental data while Bardeen equation of state gave good agreement with experimental data , the effect of high pressure and high temperature on vibration energy of atoms ( )and on heat capacity at constant volume ( ) of (NaCl-B1) are calculated by using Debye Model and gave good agreement with the theory, also thermal volume and pressure ( ),( ) and thermal expansion coefficient ( ) are calculated by using thermal equation of state by Kumar . Finally, melting curve of (NaCl-B1) was calculated by using Kumar thermal equation of state with Lindeman equation the results were compared with experimental data. Also inter ionic distance at melting ( ) for (NaCl-B1) was calculated by two ways, first by using lattce potential energy and second by using Anderson equation, and compared with data of other researcher and a good fitting was observed.

Background: One of the parameters required for the assessment of food and feed safety is detection and identification of genetically modified organisms. Legislation in some countries necessitates detection and quantification of modification in food and feed samples. Scientists have raised concern about safety of antibiotic resistance marker (ARM) genes used for transformation of crops intended for human and animal consumption. In the present work two molecular approaches have been adopted: one exploratory; for detection and quantification of ARM genes in tested plant samples and the other confirmatory; to determine the specificity/reliability of the obtained results. Results: Results revealed that primers for neomycin phosphotransferase (nptII) and aminoglycoside 3″ adenyl-transferase (aadA) were amplified in the majority of the 36 DNA screened samples. Melting curve analysis using hygromycin phosphotransferase (aphIV) gene as target sequence for the fluorescent-based detection approach was performed to ensure reliability and specificity of this procedure and to confirm results obtained by using conventional polymerase chain reaction (PCR). Quantitative RT-PCR results and validation analysis followed, revealed that all of the tested DNA samples were not violating the European legislation for GMOs labeling (0.9%). Conclusions: The results fully demonstrated the reproducibility, sensitivity/specificity of the adopted approaches for detection and quantification of even traces of GMO contents. Applying measurement uncertainty (MU) procedures presented in this work will help decision makers to ensure compliance with International Legislation and Regulations. This in its turn will facilitate and enhance trading with countries having compelling labeling regulations. [ABSTRACT FROM AUTHOR]

Quantum melting is the phenomenon of cold (zero-temperature) melting of a pressure-ionized substance which represents a lattice of bare ions immersed in the background of free electrons, i.e., the so-called one-component plasma (OCP). It occurs when the compression of the substance corresponds to the zero-point fluctuations of its ions being so large that the ionic ordered state can no longer exist. Quantum melting corresponds to the classical melting curve reaching a turnaround point beyond which it starts going down and eventually terminates, when zero temperature is reached, at some critical density. This phenomenon, as well as the opposite phenomenon of quantum crystallization, may occur in dense stellar objects such as white dwarfs, and may play an important role in their evolution that requires a reliable thermoelasticity model for proper physical description. Here we suggest a modification of our unified analytic melt-shear thermoelasticity model in the region of quantum melting, and derive the corresponding Grüneisen parameters. We demonstrate how the new functional form for the cold shear modulus can be combined with a known equation of state. One of the constituents of the new model is the melting curve of OCP crystal which we also present. The inclusion of quantum melting implies that the modified model becomes applicable in the entire density range of the existence of the solid state, up to the critical density of quantum melting above which the solid state does not exist. Our approach can be generalized to model melting curves and cold shear moduli of different solid phases of a multi-phase material over the corresponding ranges of mechanical stability.

Background: The analyses of amplification and melting curves have been shown to provide valuable information on the quality of the individual reactions in quantitative PCR (qPCR) experiments and to result in more reliable and reproducible quantitative results. Implementation: The main steps in the amplification curve analysis are (1) a unique baseline subtraction, not using the ground phase cycles, (2) PCR efficiency determination from the exponential phase of the individual reactions, (3) setting a common quantification threshold and (4) calculation of the efficiency-corrected target quantity with the common threshold, efficiency per assay and Cq per reaction. The melting curve analysis encompasses smoothing of the observed fluorescence data, normalization to remove product-independent fluorescence loss, peak calling and assessment of the correct peak by comparing its melting temperature with the known melting temperature of the intended amplification product. Results: The LinRegPCR web application provides visualization and analysis of a single qPCR run. The user interface displays the analysis results on the amplification curve analysis and melting curve analysis in tables and graphs in which deviant reactions are highlighted. The annotated results in the tables can be exported for calculation of gene-expression ratios, fold-change between experimental conditions and further statistical analysis. Web-based LinRegPCR addresses two types of users, wet-lab scientists analyzing the amplification and melting curves of their own qPCR experiments and bioinformaticians creating pipelines for analysis of series of qPCR experiments by splitting its functionality into a stand-alone back-end RDML (Real-time PCR Data Markup Language) Python library and several companion applications for data visualization, analysis and interactive access. The use of the RDML data standard enables machine independent storage and exchange of qPCR data and the RDML-Tools assist with the import of qPCR data from the files exported by the qPCR instrument. Conclusions: The combined implementation of these analyses in the newly developed web-based LinRegPCR (https://www.gear-genomics.com/rdml-tools/) is platform independent and much faster than the original Windows-based versions of the LinRegPCR program. Moreover, web-based LinRegPCR includes a novel statistical outlier detection and the combination of amplification and melting curve analyses allows direct validation of the amplification product and reporting of reactions that amplify artefacts. [ABSTRACT FROM AUTHOR]

Calcite is a widely distributed and highly significant mineral on Earth. Understanding the physical properties and melting behavior of calcite facilitates the study of global carbon cycling, mantle dynamics, geological processes, and the structure and evolution of Earth and Earth-like planets. The existing experimental and theoretical data regarding calcite are not entirely consistent, and there is a lack of high-pressure melting data. Employing first-principles molecular dynamics (FPMD) combined with the Z method, we study the melting behavior of calcite at high pressures, determining the melting temperature up to 370 GPa. Through mean square displacement (MSD), radial distribution function (RDF), coordination number (CN), and diffusion coefficient (D), the melting temperature of calcite was established, enabling further exploration of its microscopic structural characteristics. The shock melting temperatures of PANDA and ANEOS models are lower than our FPMD melting curves. Compared with two-stage light gas gun experiments, the shock melting temperature is in good agreement, but the melting curve is different from static high-pressure experiment and laser shock experiment. The calcite melting curve exceeds the mantle melting curve, suggesting that the calcium-dominated carbonate system does not undergo melting throughout the entire mantle. [ABSTRACT FROM AUTHOR]

Chromium possesses remarkable physical properties such as hardness and corrosion resistance. Chromium is also a very important geophysical material as it is assumed that lighter Cr isotopes were dissolved in the Earth’s molten core during the planet’s formation, which makes Cr one of the main constituents of the Earth’s core. Unfortunately, Cr has remained one of the least studied 3d transition metals. In a very recent combined experimental and theoretical study (Anzellini et al., Scientific Reports, 2022), the equation of state and melting curve of chromium were studied to 150 GPa, and it was determined that the ambient body-centered cubic (bcc) phase of crystalline Cr remains stable in the whole pressure range considered. However, the importance of the knowledge of the physical properties of Cr, specifically its phase diagram, necessitates further study of Cr to higher pressure. In this work, using a suite of ab initio quantum molecular dynamics (QMD) simulations based on the Z methodology which combines both direct Z method for the simulation of melting curves and inverse Z method for the calculation of solid–solid phase transition boundaries, we obtain the theoretical phase diagram of Cr to 2.5 TPa. We calculate the melting curves of the two solid phases that are present on its phase diagram, namely, the lower-pressure bcc and the higher-pressure hexagonal close-packed (hcp) ones, and obtain the equation for the bcc-hcp solid–solid phase transition boundary. We also obtain the thermal equations of state of both bcc-Cr and hcp-Cr, which are in excellent agreement with both experimental data and QMD simulations. We argue that 2180 K as the value of the ambient melting point of Cr which is offered by several public web resources (“Wikipedia,” “WebElements,” “It’s Elemental,” etc.) is most likely incorrect and should be replaced with 2135 K, found in most experimental studies as well as in the present theoretical work.

High-temperature equations of state for solid and liquid aluminum were constructed herein using experimental data on thermodynamic properties, thermal expansion, compressibility, bulk modulus and sound velocity measurements, supplemented with phase diagram data (melting curve). The entire set of experimental data was optimized using the temperature-dependent Tait equation over a pressure range of up to 800 kbar and over a temperature range from 20 K to the melting point for solid aluminum and to 3800 K for liquid aluminum. The temperature dependence of thermodynamic and thermophysical parameters was described by an expanded Einstein model. The resultant equations of state describe well the totality of experimental data within measurement errors of individual variables.

Experiments in laser‐heated diamond anvil cells (LH DACs) are conducted to assess phase diagrams of planetary materials at high pressure‐temperature (P‐T) conditions; thus, reliable determination of temperature in LH DAC experiments is essential. Radiometric temperature determination in LH DACs relies on the assumption of sample's wavelength‐independent optical properties (graybody assumption), which is not justified for major lower mantle materials. The result is that experimental phase diagrams contain systematic unconstrained errors. Here we estimate the systematic error in radiometric temperature of nongray polycrystalline bridgmanite (Bgm; Mg0.96Fe2+0.036Fe3+0.014Si0.99O3) in a LH DAC by modeling emission and absorption of thermal radiation in a sample with experimentally‐constrained optical properties. A comparison to experimental data validates the models and reveals that thermal spectra measured in LH DAC experiments record the interaction of radiation with the hot nongray sample. The graybody assumption in the experiments on translucent Bgm (light extinction coefficient, k < ∼250 cm‐1 at 500–900 nm) yields temperatures ∼5% higher than the maximum temperature in the sample heated to ∼1900 K. In contrast, the graybody temperature of dark Bgm (k > ∼1500 cm−1), such as that produced upon melt quenching in LH DACs, underestimates the maximum temperature by ∼10%. Our experimental results pose quantitative constraints on the effect of nongray optical properties on the uncertainty of radiometric temperature determination in Bgm in the LH DACs. Evaluating nongray temperature in the future would enable a revision of the Bgm to post‐perovskite phase transition and the high‐pressure melting curve of Bgm. Plain Language Summary: We modeled how the color of Earth's most abundant mineral (bridgmanite) affects temperature measurements in laser‐heated diamond anvil cell experiments with implications to the phase diagram of bridgmanite. We show that, depending on the optical properties of bridgmanite, temperature determination in such experiments may either systematically overestimate or underestimate the maximum temperature by up to 5%–10% due to the wavelength‐dependent emission and absorption in the hot sample. Overall, this study shows the phase boundaries in the bridgmanite system need revision. Key Points: Thermal radiation spectra record a nongray interaction with bridgmanite in laser‐heated diamond anvil cellsRadiometric temperature of nongray bridgmanite in laser‐heated diamond anvil cells is up to 5%–10% off the maximum sample temperatureExtant melting curves and experimental phase transition boundaries in the bridgmanite system contain this systematic error in temperature [ABSTRACT FROM AUTHOR]

Genetic variations contribute to phenotypic individual vulnerabilities to sleep debt, particularly for five single nucleotide polymorphisms (SNPs). Loop-mediated isothermal amplification and melting curve analysis (LAMP-MC) is a recently developed method to characterize SNPs. The aim of present study was to evaluate the LAMP-MC method on blood and buccal cells for detection of five SNPs of interest in healthy humans.We first analyzed signals obtained from LAMP-MC method on 42 samples. Then we compared the results with those of referent TaqMan method.The LAMP-MC method produced specific melting curves for the five SNPs. A high concordance of genotyping results was observed between the two methods for rs5751876_ADORA2A, rs1800629_TNF-α, rs73598374_ADA and rs228697_PER3 in blood and saliva (Cohen’s kappa coefficient >0.80). A good agreement ( = 0.61) was observed for rs4680_COMT in blood only.LAMP-MC is a simple and reliable method to study genetic influences on health, sleep debt-related performance impairments and countermeasures.

One of the challenges in interpreting the results obtained in qPCR is to make sure the amplicons are specific and that the melting curve analysis is used to examine it. Additional peaks in the melting curve is not always indicative of a problem, for this purpose, in this paper, a web-based tool called uMelt SM is suggested to researchers as a practical and simple way for the correct analysis of the melting curve which provides the possibility of predicting the DNA melting curve and denaturation profiles of the high-fluorescence resolution of PCR products. The results of this study showed that the melting curves were generated based on parameters were generated and an appropriate algorithm for working with this software was presented. Finally, actin and superoxide dismutase genes from Pyricularia oryzae were presented as a suitable model for determining the predicted curve using this software and Real-Time PCR curve was also drawn. Results of the uMelt SM predicted melting curves showed a high degree of compliance with the real-time PCR melting curves, which confirms the advantages of ease of use, saving time, cost, and effort in the experimentalist part when using uMelt SM software.

Abstract Background Streptococcus agalactiae or Group B Streptococcus (GBS) remains the leading cause of infections in newborns worldwilde. Prenatal GBS screening of pregnant women for vaginal-rectal colonization is recommended in many countries to manage appropriate intrapartum antimicrobial prophylaxis for those identified as carriers. In this study, a novel melting-curve based multiplex real-time PCR assay for the simultaneous detection of GBS and macrolide and lincosamide resistance markers was developed. The usefulness of the assay was evaluated for rapid and accurate prenatal GBS screening. Methods One hundred two pregnant women who were at 35–37 weeks of gestation were enrolled in this study. The analytical performance of the multiplex real-time PCR was first tested using a panel of reference and clinical bacterial and fungal strains. To test the clinical performance, vaginal-rectal swabs were obtained from pregnant women who were seen at the teaching hospital for regular prenatal care. The results of real-time were compared with those obtained from microbiological analyses. Results The real-time PCR assay showed 100% specificity and a limit of detection of 104 colony forming units equivalent per reaction. The prevalence of GBS colonization among the population studied was 15.7% (16/102) based on a positive culture and the real-time PCR results. Agreement between the two assays was found for 11 (68.75%) GBS colonized women. Using the culture-based results as a reference, the multiplex real-time PCR had a sensitivity of 91.7% (11/12, CI 59.7–99.6%), a specificity of 95.5% (86/90, CI 89.8–98.7%), a positive predictive value of 73.3% (11/15, CI 44.8–91.1%) and a negative predictive value of 98.9% (86/87, CI 92.9–99.9%). Conclusion The multiplex real-time PCR is a rapid, affordable and sensitive assay for direct detection of GBS in vaginal-rectal swabs.

Simple, multiplex qPCR methods are advantages for rapid molecular diagnosis of multiple antibiotics-resistant genes simultaneously. However, the number of genes can be detected in a single reaction tube is often limited by the fluorescence channels of a real-time PCR instrument. In this study, we developed a simple 2-D multiplex qPCR method by combining the probe colors and amplicon Tm values to overcome the mechanical limit of the machine. The principle of the novel assay was validated by detection of nine bacterial antibiotic-resistance genes (KPC, NDM, VIM, OXA-48, GES, CIT, EBC, ACC and DHA) in a single reaction tube. This assay is highly sensitive within a range of 30–3000 copies per reaction. The simplicity, rapidity, high sensitivity and specificity, and low cost of the novel method make it a promising tool for developing clinical diagnostic kits for monitoring resistance and other genetic determinants of infectious diseases. [ABSTRACT FROM AUTHOR]

Nickel is the second most abundant element in the Earth's core. However, the properties of Fe‐Ni alloys are still poorly constrained under planetary cores conditions, in particular concerning the effect of Ni on the melting curve of Fe. Here we show that Ni alloying up to 36 wt% does not affect the melting curve of Fe up to 100 GPa. However, Ni strongly modifies the hexagonal‐closed‐packed/face‐centered‐cubic (hcp/fcc) phase boundary, pushing the hcp/fcc/liquid triple point of Fe‐20wt%Ni to higher pressures and temperatures. Our results allow constraining the triple point for Fe‐10wt%Ni, a composition relevant for the Earth interior, and point out a decrease of the melting temperature at core‐mantle boundary by 400 K with respect to pure Fe. A lower amount of light elements than previously predicted is thus required to reduce the crystallization temperature of core materials below that of a peridotitic lower mantle, in better agreement with geochemical observations. Plain Language Summary: The Earth's core is believed to be composed of Fe alloyed with Ni and several lighter elements. In this paper, we investigate the effect of Ni alloying on the Fe phase diagram. The main effect of Ni addition is to enlarge the pressure/temperature stability domain of the face‐centered‐cubic (fcc) phase with respect to the hexagonal‐closed‐packed (hcp) phase and to shift the hcp/fcc/liquid triple point to higher pressures and temperatures. This implies a depression of the melting curve of Fe‐Ni alloys by around 400 K at mantle boundary conditions, at Ni concentrations pertinent for the Earth interior. This consequently decreases the temperature of the liquidus for Fe alloys constituting the Earth's core, in turn implying a reduced amount of light elements than previously predicted. Key Points: Melting curve and phase diagram of Fe‐20wt%Ni and Fe‐36wt%Ni have been investigated by in situ X‐ray absorption up to 120 GPa and 3500 KNi alloying shifts the hcp/fcc/liquid triple point to higher pressures and temperaturesThe triple point for Fe‐10wt%Ni is predicted to be around 135 GPa and 3800 K fixing new benchmarks for the Earth's core composition [ABSTRACT FROM AUTHOR]

The paper considers the order-disorder transition in a sequence of two varieties of repeating units. It is shown that the reduced free energy converges to the limit at the chain length of more than 3000. The origination of the fine structure of differential melting curves, the order–disorder transition interval, and the behavior of the fraction of junctions between the ordered and disordered phases are considered. In the primary structure, the small-scale correlations are taken into account. [ABSTRACT FROM AUTHOR]

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