Absolute Identification Research Articles

Determining the Absolute Configuration of Small Molecules by Diffusion NMR Experiments

AbstractEnantiomers are ubiquitous in many areas of science, such as pharmaceuticals, agriculture, and food. Nuclear magnetic resonance (NMR) alone is not able to differentiate enantiomers as their spectra are identical. However, these can be distinguished using chiral auxiliaries (such as chiral complexing agents) that form diastereomeric complexes, but absolute identification is still troublesome, usually requiring a chemical reaction with a chiral derivatizing agent. Here, we propose a new method that uses a hybrid mixture of solvating agents in a simple comparison of diffusion NMR experiments, which can discriminate enantiomers in both frequency and diffusion domains, dubbed CHIMERA (CHIral Micelle Enantiomer Resolving Agent). The new method was assessed for twenty‐three small chiral molecules using a combination of BINOL and (−)‐DMEB, a chiral surfactant, and initial results indicate that absolute configuration can be obtained from a simple experiment.

Determining the Absolute Configuration of Small Molecules by Diffusion NMR Experiments.

Enantiomers are ubiquitous in many areas of science, such as pharmaceuticals, agriculture, and food. Nuclear magnetic resonance (NMR) alone is not able to differentiate enantiomers as their spectra are identical. However, these can be distinguished using chiral auxiliaries (such as chiral complexing agents) that form diastereomeric complexes, but absolute identification is still troublesome, usually requiring a chemical reaction with a chiral derivatizing agent. Here, we propose a new method that uses a hybrid mixture of solvating agents in a simple comparison of diffusion NMR experiments, which can discriminate enantiomers in both frequency and diffusion domains, dubbed CHIMERA (CHIral Micelle Enantiomer Resolving Agent). The new method was assessed for twenty-three small chiral molecules using a combination of BINOL and (-)-DMEB, a chiral surfactant, and initial results indicate that absolute configuration can be obtained from a simple experiment.

On the Criminal Compulsory Appraisal in China and Its Improvement

Criminal compulsory appraisal is not only not clearly stipulated in our laws, but also controversial in the theoretical circles. Through the legal combing and empirical analysis, it is found that the compulsory appraisal under the meaning of “the responsibility of specialized organs” exists in a large number of China's criminal judicial practice, and the compulsory appraisal under the meaning is more conducive to the restriction of the arbitrariness of the specialized organs, and the protection of the rights and interests of the parties. And then for the system status quo, put forward “ expand ‘absolute compulsory identification', strict ‘relative compulsory identification', legal ‘factual compulsory identification' "In order to improve the criminal compulsory identification system in China, we propose to expand ‘absolute compulsory identification', strict ‘relative compulsory identification', statutory ‘factual compulsory identification'.

Sparse identification of dynamical systems by reweighted [formula omitted]-regularized least absolute deviation regression

This work proposes a generalized methodology for sparse identification of dynamical systems (SID), utilizing reweighted l1-regularized least absolute deviation (LAD) regression to recover the governing equation of dynamical systems. To programmatically implement the proposed method, a stabilized and efficient resolution scheme is developed by combining the solution method of the classical LAD-based least absolute shrinkage and selection operator (LAD-lasso) and the threshold iterative idea of the sequentially thresholded least-squares (STLS) method. The new method relaxes the assumption of normality for the error terms in the linear regression model employed by traditional SID techniques. Additionally, it overcomes the low identification accuracy deficiency of the recently proposed regularized least absolute deviation-based sparse identification of dynamics method (RLAD-SID) under some poor data conditions. The performance of the proposed approach is investigated by simulations of two well-known dynamical systems, that is, the Lorenz system and the Duffing system. The reliability of this approach in recovering the governing equation of dynamical systems from noise-contaminated datasets is firstly demonstrated. Furthermore, the advantage of the proposed method is illustrated by comparing it with four traditional techniques in relatively poor data environments. Finally, we display the robustness of the new method when the time derivative dataset is affected by different types of noise, and reveal its superiority compared to the traditional RLAD-SID.

Analysis Of 4-Bit Absolute Value Detector for ECG Signal Comparation

In the present era, where numerous heart conditions are prevalent, the significance of monitoring cardiac electrical signals has surged within the medical realm. Within this study, we leverage Complementary Metal Oxide Semiconductor (CMOS) and Pass-transistor Logic (PTL) methodologies for crafting and refining a 4-bit absolute value detection mechanism. This mechanism serves to identify and juxtapose electrocardiogram (ECG) signals. The 4-bit absolute value detection system is bifurcated into two core segments: one for absolute value identification and the other for comparative analysis. This setup facilitates a binary input's comparison with a predetermined threshold, thereby yielding a corresponding comparative outcome. Subsequently, a meticulous assessment is conducted on the lengthiest pathway, which is then subject to refinement through gate sizing and voltage supply (Vdd) adjustments. The findings unveil a delay of 34.13tp0 and an energy dissipation of 184.832 C. The resultant 4-bit absolute value detection mechanism, borne from this research institution's efforts, emerges as an invaluable asset in the medical domain, attributed to its exceptional optimization with respect to minimal delay and energy outlay.

A Partial Approximate Least Absolute Deviation-Based Identification Algorithm for a Multivariable Closed-Loop System with Spike Noise

Considering the stability and safety of industrial production, the open-loop system cannot meet the requirements of industrial production, so more and more attention has been paid to multivariable closed-loop system identification. This study focuses on the identification of a multivariate closed-loop system with spike noise in which the model order of the feedback channel is lower than that of the forward channel. Combining principal component analysis (PCA), which is used to eliminate the correlation between the data matrix elements, and the derivable approximate least absolute criterion function, partial approximate least absolute deviation (PALAD) for multivariable closed-loop system identification is proposed. By introducing a deterministic function to replace the absolute value in partial approximate least absolute deviation, the non-differentiable problem of the least absolute deviation function can be solved, and the identifiability of the multivariable closed-loop system in the case mentioned above is theoretically verified. Simulation experiments show the validity of the PALAD algorithm. Compared with the partial least squares (PLS) method, PALAD can effectively restrain the spike noise that follows an SαS distribution and shows stronger robustness when white and spike noises exist simultaneously.

Individual differences in absolute identification as a function of autistic trait levels.

The present study aimed to examine the links between a self-report measure known to be discriminative of autism (the AQ-10) and performance on the classic unidimensional absolute identification judgment task with 10 line lengths. The interest in this task is due to the fact that discriminating absolutely between such items is quite perceptually challenging and also that it is not very amenable to generalization. Importantly, there are two currently available views of perceptual learning in autism that suggest that those higher on the autism spectrum might have an advantage on this task. Results showed, however, that for N = 291 typically developing individuals, higher scores on the AQ-10 (and also on a measure of the degree to which individuals self-report having a more spontaneous, activist-type learning style) tended to relate to lower levels of accuracy on this task in contrast to what was expected. One explanation furthered for this result was that those with higher AQ-10 scores may have had more difficulties maintaining the overall stimulus context in memory. Such work adds greatly to knowledge of the nature of the individual differences that can affect performance on this particular task.

Learning spatial frequency identification through reweighted decoding.

Perceptual learning, the improvement of perceptual judgments with practice, occurs in many visual tasks. There are, however, relatively fewer studies examining perceptual learning in spatial frequency judgments. In addition, perceptual learning has generally been studied in two-alternative tasks, occasionally in n-alternative tasks, and infrequently in identification. Recently, perceptual learning was found in an orientation identification task (eight-alternatives) and was well accounted for by a new identification integrated reweighting theory (I-IRT) (Liu et al., submitted). Here, we examined perceptual learning in a similar eight-alternative spatial frequency absolute identification task in two different training protocols, finding learning in the majority but not all observers. We fit the I-IRT to the spatial frequency learning data and discuss possible model explanations for variations in learning.

Autocorrelation in category judgement.

Jesteadt et al. discovered a remarkable pattern of autocorrelation in log estimates of loudness. Responses to repeated stimuli correlated to about +0.7, but that correlation was much reduced (0.1) following large differences between successive stimuli. The experiment reported here demonstrates the same pattern in absolute identification without feedback; if feedback is supplied, the pattern is much muted. A model is proposed for this pattern of autocorrelation, based on the premise: "There is no absolute judgment of sensory magnitudes; nor is there any absolute judgment of differences/ratios between sensory magnitudes." Each stimulus in an experiment is compared with its predecessor, greater, less than, or about the same. The variability of that comparison increases with the difference in magnitude between the stimuli, so the assessment of a stimulus far removed from its predecessor is very uncertain. The model provides explanations for the apparent normal variability of sensory stimuli, for the "bow" effect and for the widely reported pattern of sequential effects. It has applications to the effects of stimulus range, to the difficulty of identifying more than five stimuli on a single continuum without error, and to inspection tasks in general, notably medical screening and the marking of examination scripts.

An Online Condition-Based Parameter Identification Switching Algorithm for Lithium-Ion Batteries in Electric Vehicles

Safely and reliably managing the lithium-ion batteries in electric vehicles for daily operations relies on accurate state-of-charge estimation. To pursue accurate state-of-charge estimation, battery electric circuit model-based algorithms demand minimized modeling error from accurate parameter identifications. Typical online parameter identification algorithms: least square fitting approach and recursive least square fitting are commonly adopted but have their limitations and issues with continuously providing accurate identification results. To overcome their problems and utilize their strengths, this paper proposes a condition-based parameter identification switching algorithm. The proposed algorithm accurately and robustly identifies the lithium-ion batteries' parameters based on the battery data condition and the adoption of Bollinger bands. By minimizing the modeling error, the accuracy of the state-of-charge estimation is thus improved. The electric vehicle simulation results indicate that the proposed algorithm can improve the parameter identification accuracy by an average of 70.80% and 44.95% reduction in the mean absolute parameter identification error, compared to typical least square fitting and recursive least square fitting approaches. With the help of the minimized modeling error, the state-of-charge estimation accuracy can thus be improved, rendering an average of 62.44% and 21.49% improvement.

Regularized least absolute deviation-based sparse identification of dynamical systems.

This work develops a regularized least absolute deviation-based sparse identification of dynamics (RLAD-SID) method to address outlier problems in the classical metric-based loss function and the sparsity constraint framework. Our method uses absolute derivation loss as a substitute of Euclidean loss. Moreover, a corresponding computationally efficient optimization algorithm is derived on the basis of the alternating direction method of multipliers due to the non-smoothness of both the new proposed loss function and the regularization term. Numerical experiments are performed to evaluate the effectiveness of RLAD-SID using several exemplary nonlinear dynamical systems, such as the van der Pol equation, the Lorenz system, and the 1D discrete logistic map. Furthermore, detailed numerical comparisons are provided with other existing methods in metric-based sparse regression. Numerical results demonstrate that (1) RLAD-SID shows significant robustness toward a large outlier and (2) RLAD-SID can be seen as a particular metric-based sparse regression strategy that exhibits the effectiveness of the metric-based sparse regression framework for solving outlier problems in a dynamical system identification.

Metagenomic study of the tomato rhizosphere soil microbiome: current state and prospect

<abstract> <p>Plant microbiota has a variety of impacts on the plant. Some are beneficial, while some are pathogenic. This study discusses the general metagenomics procedures in processing plant-related metagenomes and focuses on the tomato plants' rhizosphere species. Metagenomics, associated with eventual DNA, is isolated from environmental samples and thus permits absolute microbial population identification. Meanwhile, the genetic content of the DNA sample obtained allows the functional capability identification and biochemical procedure of many microorganisms. This review reveals the recent utilization and application of the potential of Next-Generation Sequencing (NGS) in agriculture. It involves plant-associated microbiota, the factors driving their diversity, and plant metagenome to tackle current challenges experienced in food security. This review provides the newest methods for rapidly identifying the microbial communities inhabiting the rhizosphere soil of tomato plants.</p> </abstract>

Comparative urine metabolomics of mice treated with non-toxic and toxic oral doses of (-)-epigallocatechin-3-gallate.

The green tea polyphenol, (-)-epigallocatechin-3-gallate (EGCG), has been studied for its potential positive health effects, but human and animal model studies have reported potential toxicity at high oral bolus doses. This study used liquid chromatography-mass spectrometry-based metabolomics to compare the urinary EGCG metabolite profile after administration of a single non-toxic (100 mg kg-1) or toxic (750 mg kg-1) oral bolus dose to male C57BL6/J mice to better understand how EGCG metabolism varies with dose. EGCG metabolites, including methyl, glucuronide, sulfate, and glucoside conjugates, were tentatively identified based on their mass to charge (m/z) ratio and fragment ion patterns. Partial least squares discriminant analysis (PLS-DA) results showed clear separation of the urine metabolite profiles between treatment groups. The most differentiating metabolites in the negative and positive ion modes were provisionally identified as di-glucuronidated EGCG quinone and di-glucuronidated EGCG, respectively. The presence of EGCG oxidation products at toxic dose is consistent with studies showing that EGCG toxicity is associated with oxidative stress. Relative amounts of methylated metabolites increased with dose to a lesser extent than glucuronide and sulfate metabolites, indicating that methylation is more prominent at low doses, whereas glucuronidation and sulfation may be more important at higher doses. One limitation of the current work is that the lack of commercially-available EGCG metabolite standards prevented absolute metabolite quantification and identification. Despite this limitation, these findings provide a basis for better understanding the dose-dependent changes in EGCG metabolism and advance studies on how these differences may contribute to the toxicity of high doses of EGCG.

Performance of Bleach Method Sputum Smear Microscopy for the Diagnosis of Tuberculosis in a Highly Endemic District in Lima, Peru.

Background: Sputum smear microscopy (SSM) is a screening test used to diagnose tuberculosis (TB); however, its performance and sensitivity are relatively low, which can lead to false negatives. We designed a cross-sectional study to estimate the performance of SSM that includes a pretreatment based on sputum digestion with bleach (sodium hypochlorite) for the diagnosis of TB. Methods: We evaluated 73 sputum samples from patients with a diagnosis of TB confirmed by the Xpert MTB/RIF test and 114 samples from patients without TB. We performed sputum digestion using a 5% sodium hypochlorite solution, centrifuged at 2000 rpm for 15 min. We prepared smears for direct and bleach-treated SSM and used Ziehl−Neelsen staining. Results: The bleach-treated SSM obtained absolute identification of the cases of TB confirmed by the Xpert test, compared to 95.9% identified by the direct smear method (without bleach treatment). We also found a significant increase (p < 0.001) in the recovery of acid-fast bacilli (AFB) obtained by the bleach-treated SSM (293.8 ± 215.1 AFB) compared to the direct SSM method (222.9 ± 195.5 AFB). The AUC of the bleach-treated SSM and direct SSM was 100% and 96.6%, respectively. Conclusion: The bleach-treated SSM performs better than the direct SSM in identifying AFB and increasing the bacillary count in the sputum samples.

DIFFERENT ANATOMY OF EXTRAHEPATIC BILE DUCT IN PATIENTS WITH CALCULOUS CHOLECYSTITIS: CLINICAL OBSERVATIONS

Summary. The aim of investigation – to get acquainted with the possibilities of variant anatomy of the extrahepatic bile ducts location.&#x0D; Results and their discussion. In our own practice, we observed two patients with the extrahepatic bile ducts atypical anatomy.&#x0D; Patient G. was operated because of chronic calculous cholecystitis. During laparoscopic cholecystectomy, we encountered the following situation: it was found that the gallbladder has a very short duct directly in the region of the portal of the liver. After dissection it was found that d. cysticus flows into the right hepatic duct. Timely establishment of this variant anatomy, which was achieved by careful dissection of the junction area d. cysticus and d. hepaticus dexter, allowed to prevent (in this case) wrong clipping of the right hepatic duct. In this example the possibility of timely establishing the presence of anatomical features of the extrahepatic bile ducts made it possible to prevent their damage.&#x0D; Patient K. was operated because of calculous cholecystitis, choledocholithiasis (without clinical and laboratory signs of mechanical jaundice). During laparoscopic cholecystectomy, it was established that the patient has variant anatomy of the extrahepatic bile ducts, when the right hepatic duct drains directly into the gallbladder. This anomaly was discovered after the separation of the gallbladder from its bed, as a result of which this duct was damaged. The access conversion was performed, the place of exit from the liver in the area of the gallbladder of the anomalous right hepatic duct was established. In order to restore the outflow of bile, a right-sided hepaticojejunostomy was performed on a Roux loop, external drainage of the choledoch according to Ker, drainage of the abdominal cavity.&#x0D; Conclusions. Although laparoscopic cholecystectomy is a standard routine operation, the variability of extrahepatic bile duct location should be considered.&#x0D; We consider it expedient during dissection in the area of the transition of the vesical duct to the hepaticocholedoch to carefully isolate all anatomical structures until their absolute identification.

Analytical Procedure for determination and statistical validation of novel drug Mafenide acetate in pharmaceutical formulations

Requirement for a sophisticated analytical method using HPLC and HPTLC is in high demand to meet the needs of a small scale industry for analysis of drugs that are relatively expensive. Hence a simple method was proposed in the routine determination of Mafenide acetate in pharmaceutical formulations and bulk dosage forms that can be less expensive. An analytical method was developed for the estimation of Mafenide acetate drug substance by liquid chromatography. The chromatographic separation was achieved on phenyl column (Eclipse XDB-Phenyl 250*4.6, 5um) at ambient temperature. The separation was achieved employing a mobile phase consisting of 0.1 %v/v Trifluoroacetic acid in water: Methanol (10:90). The flow rate was 1.0 ml/ minute and ultraviolet detector at 245nm. The average retention time for Mafenide acetate was 3.3 minutes. The proposed method was validated for selectivity, precision, linearity and accuracy. All validation parameters were checked and are found within the acceptable range. The assay methods were found to be linear ranging from 50-150 µg/ml for Mafenide acetate. The parameters considered for the procedure are related limit, selectivity, linearity, range, accuracy and precision are defined. Thesample solution leads to unequivocal, absolute identification of the analyte peak of interest apart from all other matrix components. The objective of our work is to form a basis for production procedure and control, which are designed to assure that the drug products have the identity, Quality, and purity. The results obtained could be treated as simple, sensitive and reproducible for determination of Mafenide acetate in pharmaceutical formulations.

A skeletal remains unrevealed the murder mystery of missing lady through DNA technology

In 1985, Alec Jeffreys first discovered and described the absolute identification technique through genomic DNA, which leads to open a new arena of forensic science. Since then, it has been adopted for crime-solving as well as various forensic applications across the globe. After the discovery of DNA technology, it passes through several continuous developmental steps concerning sensitivity, reduction in turnaround time, cost effect, minimizing multiple handling of the sample, and suitable challenging samples. After three and half decades of this DNA technology, Short Tandem Repeat (STR) based DNA technology established gold standard and irreplaceable technique in the field of forensic science, which is entirely different from its inception. In the present study, with help of DNA technology, a murder mystery of missing women was solved. In this case, tooth and bone pieces of deceased and blood samples of probable mother and son of deceased were received for DNA test in the laboratory. STR based 20 autosomal STR markers and one sex-determining Amelogenin marker included in PowerPlex® 21 systems kit was used for identification of unknown deceased. Based on the genetic marker unknown deceased was identified as biologically related to the probable mother and son of the deceased.

Isobaric Tags for Relative and Absolute Quantitation Identification of Blood Proteins Relevant to Paroxetine Response in Patients With Major Depressive Disorder.

ObjectivesIsobaric tags for relative and absolute quantitation (iTRAQ) is a proteomic investigation that could be utilized for rapid identification and quantification of proteins, which we would use to identify differentially expressed proteins in treatment responsive patients with major depressive disorder (MDD).MethodsSix treatment responsive patients of MDD were recruited, and their peripheral blood mononuclear cell (PBMC) were collected before and after 4 weeks of paroxetine treatment. iTRAQ and Mascot search engine were used to detect differentially expressed proteins, which were then validated by Western blot.ResultsTwo thousand one hundred and fifty three proteins were screened, and seven proteins showed differences of more than two-fold and 62 proteins with a differences of less than two-fold. Six proteins with commercially available antibodies were identified, and were validated by Western blot in 10 paroxetine responsive MDD patients. Putative hydroxypyruvate isomerase (HYI), eukaryotic translation initiation factor 4H (eIF4H), and RNA binding motif 8A (RBM8A) had statistically significant differences before and after treatment in the validation. Data are available via ProteomeXchange with identifier PXD028947.ConclusionsBy using iTRAQ and Western blot, we were able to identify HYI, eIF4H, and RAM8a to be the potential predictors of paroxetine treatment response in patients with MDD. This finding could help establish future individualized medicine.

Synthesis of Human Phase I and Phase II Metabolites of Hop (Humulus lupulus) Prenylated Flavonoids.

Hop prenylated flavonoids have been investigated for their in vivo activities due to their broad spectrum of positive health effects. Previous studies on the metabolism of xanthohumol using untargeted methods have found that it is first degraded into 8-prenylnaringenin and 6-prenylnaringenin, by spontaneous cyclisation into isoxanthohumol, and subsequently demethylated by gut bacteria. Further combinations of metabolism by hydroxylation, sulfation, and glucuronidation result in an unknown number of isomers. Most investigations involving the analysis of prenylated flavonoids used surrogate or untargeted approaches in metabolite identification, which is prone to errors in absolute identification. Here, we present a synthetic approach to obtaining reference standards for the identification of human xanthohumol metabolites. The synthesised metabolites were subsequently analysed by qTOF LC-MS/MS, and some were matched to a human blood sample obtained after the consumption of 43 mg of micellarised xanthohumol. Additionally, isomers of the reference standards were identified due to their having the same mass fragmentation pattern and different retention times. Overall, the methods unequivocally identified the metabolites of xanthohumol that are present in the blood circulatory system. Lastly, in vitro bioactive testing should be applied using metabolites and not original compounds, as free compounds are scarcely found in human blood.

Phytochemical Screening and Characterization of Agarwood (Aquilaria malaccensis) Chips Wood Grade as Incense Headspace Volatile Compounds by GC-MS.Ms.Q.TOF, SPME

AbstractAgarwood (Aquilaria malaccensis) is an Asian tree traditionally used for many medicinal purposes, its oil constituents and inhaled vapor has sedative, antidepressant and anxiolytic activities. Gas Chromatography and quadruple time of flight –mass spectrometry (GC.MS.MS/Q.TOF) in the MS-MS mode has been used in screening and identification of multiple compounds of three different grade of agarwood chipwood, using DB-1 column which led to identification of 96 compounds while the majority of the compounds about 500 compounds remain UN knowing to the difficulties of confirming or rejecting them . The generated results were so complicated and very difficult to be interpreted for the presence of isomers with similar matched spectrums; the absence of official standard references for these compounds make the judgment of confirming the identified compounds more complicated and very hard to absolute identification to be assessed. The compounds were extracted by applying a solvent less technique; trapping incense and volatile headspace. The total Ion chromatogram detected compounds are distributed among different array over the chemical families among monoterpenes, sesquiterpenes, hydrocarbons, oxygenated monoterpenes, sesquiterpenes, norterpenoids and diterpenoids ,short chain glycols, carboxylic acids and others. The flowing compounds are the major terpene, sesquiterpene and oxygenated sesquiterpenoid found in all grades of A. malaccensis chipswood under investigation, furthermore; the study represented that the characterization of compounds from agarwood chips wood is highly possible through incense volatile sample.