Hasil untuk "Analytical chemistry"

Sali Muriqi, Libor Červenka, Milan Sýs

Research background. Nowadays, there is still no portable electroanalytical device suitable for the monitoring concentration of chlorophenols in technologically used water, especially in the brewing industry. This problem could be solved by developing an electroanalytical screening method based on chlorophenol anodic oxidation. Experimental approach. The electrochemical behaviour of the target chlorophenols was investigated to find the optimum working conditions for their selective electrochemical detection in beer. Results and conclusions. Electrochemical oxidation pathways were proposed for each investigated chlorophenol. The sum of all chlorophenols present in the brewing water, expressed as the concentration equivalent of 2,6-dichlorophenol, can be determined electrochemically, so that in future real-time monitoring of chlorophenols in the individual stages of the beer production process will be possible. Moreover, the cathodic reduction of their oxidation products proved to be a suitable electroanalytical tool for the selective detection of their presence in beer. Novelty and scientific contribution. The research shows that an electroanalytical approach could be useful in the control of beer biotechnology to prevent sensory changes caused by the chlorophenols formed.

Huy Pham, Juliana Cardoso Neves, Rongjing Yan et al.

Shiwei Liu, Chun-ao Wei, Miaoxin Li et al.

Abstract This work explores the extraction of the spatial distribution and chemical composition information of pigments in colored relics through visible spectral images. An adaptive superpixel segmentation method is proposed to extract the spatial distribution information of pigments. Quadtree decomposition is applied to generate nonuniform initial seed points based on the image homogeneity. These seed points are used as the initial cluster centers in an extended simple linear iterative clustering (SLIC) algorithm for visible spectral images to create superpixels of varying sizes that reflect the homogeneity. Each superpixel is subsequently treated as an individual area in the colored relics, and a pigment identification method based on the visible spectral reflectance is proposed to identify the pigments in these areas. A standard reference database is constructed using samples that simulate the painting process of ancient wall paintings in the Mogao Grottoes. Geometric features, which are characterized by the linear combination of the normalized visible spectral reflectance, its slope and its curvature, are designed to represent the chemical composition of pigments. The geometric features of the superpixels are compared with those of the pigments in the database using the Euclidean distance to determine the pigments in each area of the colored relics. This work is expected to provide scientific guidance for pigment selection in the color restoration of colored relics.

Venkatesan Keerthika, Venkatesan Santhosh, Manivannan N

Hibiscus sabdariffa L. (Rosella) has a long history of use in food preparation, herbal remedies, hot and cold beverages, food industry flavoring, and herbal drinks. More than 300 species of Hibiscus are grown all over the world. It is an annual herbaceous shrub belonging to the family Malvacea. However, limited is known about the antimicrobial properties of H. sabdariffa; the purpose of this study was to investigate the antimicrobial activity of H. sabdariffa (Rosella) extract against a range of pathogens, including Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans. The results of the study showed that H. sabdariffa (Rosella) extract had a significant antimicrobial effect, against S. aureus and E. coli. Further the minimum inhibitory concentration (MIC) shows 128 μg/mL concentration followed by E. coli 256 μg/mL. The biocompatibility of crude metabolites shows highly compatible with Red blood cells (RBC’s). This finding suggests that the crude metabolites of H. sabdariffa (Rosella) could be the source to control the human pathogens.

Ponniah Subramanian, Brahmananda Dutta, Ashtha Arya et al.

Smart materials encompass a variety of substances, including smart antimicrobial peptides, pit and fissure sealants, impression materials, cement, and sutures. These materials can change properties under specific stimuli such as temperature, stress, moisture, pH, or electric and magnetic fields. These constituents signify the commencement of a novel era or epoch in the field of smart dentistry and exhibit the potential for enhanced efficacy in the future.

Zhuopeng Li, Xuan Hu, Xiaochenyang Jiang et al.

Abstract This study utilizes a multidisciplinary approach, combining simulation experiments, thermal expansion analysis, XRD, SEM, and physical property assessments to investigate the firing temperature in illitic-kaolinitic porcelain. Our findings indicate that the accuracy of the thermal expansion method depends on both the actual firing temperature and dwell time. When dwell time is uncertain, the method provides a range of possible actual firing temperatures, differing by approximately 100 °C. Remarkably, as the porcelain body nears full vitrification, the determined firing temperature tends to be notably higher. A critical analysis of previous research suggests potential overestimation of ancient kiln temperatures. Additionally, our study highlights the usefulness of bulk density, water absorption, porosity, and mullite content in determining dwell time. Overall, our research offers new insights into ancient porcelain firing processes.

Luyao Liu, Lei Liu, Yan Wang et al.

Abstract The lack of efficient biomarkers for the early detection of gastric cancer (GC) contributes to its high mortality rate, so it is crucial to discover novel diagnostic targets for GC. Recent studies have implicated the potential of site‐specific glycans in cancer diagnosis, yet it is challenging to perform highly reproducible and sensitive glycoproteomics analysis on large cohorts of samples. Here, a highly robust N‐glycoproteomics (HRN) platform comprising an automated enrichment method, a stable microflow LC‐MS/MS system, and a sensitive glycopeptide‐spectra‐deciphering tool is developed for large‐scale quantitative N‐glycoproteome analysis. The HRN platform is applied to analyze serum N‐glycoproteomes of 278 subjects from three cohorts to investigate glycosylation changes of GC. It identifies over 20 000 unique site‐specific glycans from discovery and validation cohorts, and determines four site‐specific glycans as biomarker candidates. One candidate has branched tetra‐antennary structure capping with sialyl‐Lewis antigen, and it significantly outperforms serum CEA with AUC values > 0.89 compared against < 0.67 for diagnosing early‐stage GC. The four‐marker panel can provide improved diagnostic performances. Besides, discrimination powers of four candidates are also testified with a verification cohort using PRM strategy. This findings highlight the value of this strong tool in analyzing aberrant site‐specific glycans for cancer detection.

Alexander Weiß, Manuel Dutschke, Carla Vogt et al.

Khadiga M. Kelani, Ahmed M. W. Nassar, Gamal A. Omran et al.

Abstract Two Chromatographic methods have been established and optimized for simultaneous determination of serdexmethylphenidate (SER.DMP) and dexmethylphenidate (DMP) in the presence of their degradation products. The first method is a reversed phase high performance liquid chromatography with diode array detection (HPLC–DAD). Isocratic separation was carried out on Waters X-bridge Shield RP18 column (150×3.9×5 μm particle size) using a mixture of 5 mM phosphate buffer (pH 5.5): acetonitrile (40:60, v/v) as a mobile phase, flow rate 1 mL/min and detection at 220 nm. The second method is a thin-layer chromatography (TLC)—densitometry method using methanol: chloroform (70:30, v/v) as a mobile phase and UV scanning at 220 nm. In HPLC method, the linearity range of SER.DMP was (2.5–25 μg/mL); with LOD (0.051 μg/mL) and LOQ (0.165 μg/mL) while for DMP was (2.5–25 μg/mL); with LOD and LOQ of (0.098 μg/mL) and (0.186 μg/mL), respectively. For TLC method the sensitivity range of SER.DMP was (5–25 μg/mL), LOD was (0.184 μg/spot), while LOQ was (0.202 μg/ spot) whereas for DMP the sensitivity range was (5–25 μg/mL) with LOD of (0.115 μg/ spot) and LOQ of (0.237 μg/ spot), respectively. SER.DMP was found to be equally labile to acidic and alkaline hydrolysis, whereas DMP was sensitive to acidic hydrolysis only. Both drugs were successfully determined in presence of acidic and basic degradants by the two developed methods (stability indicating assay method). Chromatographic separation of the degradation products was carried out on TLC aluminum silica plates 60 F254, as a stationary phase, using methanol: dichloroethane: acetonitrile (60:20:20 v/v), as a mobile phase. The degradation pathway was confirmed using TLC, IR, 1H-NMR and mass spectroscopy; moreover, the separation power was correlated to the computational results by applying molecular dynamic simulation. The developed methods were validated according to the International Conference on Harmonization (ICH) guidelines demonstrating good accuracy and precision. They were successfully applied for quantitation of SER.DMP and DMP in pure and capsule forms. The results were statistically compared with those obtained by the reported method in terms of accuracy, precision and robustness, and no significant difference was found.

Murukesan Subramanian, Kishore Kumar Selvaraj, Raghunathan Jagannathan et al.

Plaque control, pain control, and modulation of inflammatory mediators to accelerate or stabilize tooth movements are hot issues in orthodontics. The recent advent of phytochemicals as biological mediators has opened new vistas in the aforementioned areas of orthodontics. Adhatoda vasica has caught the attention of investigators due to multiple properties related to orthodontics. This study addresses the potential areas of use of A. vasica in orthodontics, which provide ideas for further investigations. A. vasica possesses antibacterial activity, antifungal activity, anti-oxidant effect, anti-inflammatory activity, analgesic effect, osteogenic, and osteoclastic activities. A. vasica has huge potential in orthodontics, whereas all these vistas need careful and methodical testing before use in clinical orthodontics. In the future, investigators can focus on these aspects of the use of A. vasica to develop products.

Marta Sharafan, Karolina Jafernik, Halina Ekiert et al.

<i>Illicium verum</i> Hook f. (star anise) is considered an important species in Traditional Chinese Medicine and is also used in contemporary medicine in East Asian countries. It occurs in natural habitats in southeastern parts of China and Vietnam, and is cultivated in various regions in China. The raw materials—<i>Anisi stellati fructus</i> and <i>Anisi stellati aetheroleum</i> obtained from this species exhibit expectorant and spasmolytic activities. <i>The European Pharmacopoeia</i> (4th edition) indicates that these raw materials have been used in allopathy since 2002. The biological activities of the above-mentioned raw materials are determined by the presence of valuable secondary metabolites such as monoterpenoids, sesquiterpenoids, phenylpropanoids, and flavonoids. Recent pharmacological studies on fruit extracts and the essential oil of this species have confirmed their antibacterial, antifungal, anti-inflammatory, and antioxidant activities and thus their medicinal and cosmetic value. The aim of this review was to examine the progress of phytochemical and pharmacological studies that focused on possible cosmetic applications. In addition to fruit extracts and essential oil, the current consensus on the safety of <i>trans</i>-anethole, which is the main compound of essential oil used in cosmetology, is underlined here.

Dawid Szyba, Anna Bajorek, Dorota Babilas et al.

New resorbable Ca32Mg12Zn38Yb18-2xBxAux (x = 1,2) alloys were designed and prepared in order to verify their use for medical applications as potential short-term implants. Their amorphous structure containing some crystalline phases (CaZn, CaZn2 and MgZn) was determined by X-ray and neutron diffraction and electron microscopy methods. The biocorrosion behavior of the plates was tested by hydrogen evolution measurements, immersion, electrochemical polarization tests, and electrochemical impedance spectroscopy in Ringer's solution at 37 °C. The corrosion analysis was also supplemented by X-ray diffraction, photoelectron, and ICP-AES spectroscopy. The corrosion resistivity measurements revealed that the alloys manifest enhanced corrosion resistance. The corrosion current density for Ca32Mg12Zn38Yb18-2xBxAux (x = 1, 2) alloys were 18.46 and 8.79 μA/cm2, which is lower than for pure Mg (47.85 μA/cm2) and Zn (33.96 μA/cm2). A decreasing tendency for hydrogen to evolve as a function of time was noted. The hydrogen evolution did not exceed 1 ml/cm2 over 1 h and average corrosion rate is calculated as 0.32 g/m2 . h for Ca32Mg12Zn38Yb14B2Au2 alloy after 312 h. The corrosion mechanism of the alloys includes an anodic dissolution, a hydroxide precipitation, corrosion product layer formation and corrosion propagation stage.

Umesh Kumar, Supriya Sharma, Manjunath Durgappa et al.

Objectives: Acute-on-chronic liver failure (ACLF), which develops in patients with underlying alcoholic liver disease (ALD), is characterized by acute deterioration of liver function and organ failures are secondary to that. The clear understanding of metabolic pathways perturbed in ALD-ACLF patients can greatly decrease the mortality and morbidity of patients through predicting outcome, guiding treatment, and monitoring response to treatment. The purpose of this study was to investigate the metabolic disturbances associated with ACLF using nuclear magnetic resonance (NMR)-based serum metabolomics approach and further to assess if the serum metabolic alterations are affected by the severity of hepatic impairment. Materials and Methods: The serum-metabolic profiles of 40 ALD-ACLF patients were compared to those of 49 age and sex-matched normal-control (NC) subjects making composite use of both multivariate and univariate statistical tests. Results: Compared to NC, the sera of ACLF patients were characterized by significantly decreased serum levels of several amino acids (except methionine and tyrosine), lipid, and membrane metabolites suggesting a kind of nutritional deficiency and disturbed metabolic homeostasis in ACLF. Twelve serum metabolic entities (including BCAA, histidine, alanine, threonine, and glutamine) were found with AUROC (i.e., area under ROC curve) value >0.9 suggesting their potential in clinical diagnosis and surveillance. Conclusion: Overall, the study revealed important metabolic changes underlying the pathophysiology of ACLF and those related to disease progression would add value to standard clinical scores of severity to predict outcome and may serve as surrogate endpoints for evaluating treatment response.

Qiuyang Pan

Abstract The study examines omissions in the English version of Little Red Riding Hood in contrast to the Chinese one. The research is aimed at studying the linguistic effects of inculturation and the choice of translation strategies to convey a truthful intercultural component. The study examines the Little Red Riding Hood story by Leray (2011) translated into Englishand Chinese languages. The Chinese version of the story was edited and published by Green and Green (1953). The analysis of the translation in a cultural context is based on the omission strategy. The analysis of semantically redundant words and sentences in the English version of Little Red Riding Hood has been carried out in contrast to the Chinese one, where no omissions were found. The purpose of the study is to analyze the relationship between the versions of Little Red Riding Hood and the evolution of European and Chinese moral ideology. The novelty of the research lies in the fact that two translations are considered in the context of the Tehrani’s (2013) method using a phylogenetic approach and the strategy of omission to determine moral codes. As a result of a comparative analysis of the target translation, ten omissions were found: four brief descriptions and six complete omissions. The omission strategy reflected the cross-cultural and informative ideological features of the two cultures. Adhering to the phylogenetic concept by Tehrani, the target language of Little Red Riding Hood was identified as English because the Chinese version of the story was translated from English (Zhengzhong Bookstore, 1967). There are also some distinguishing characteristics of the initial collision: the characteristics of the protagonist, the characteristics of the villain, the methods of deceiving the future victim by the villain and the ending options. The folk European collision of the fairy tale originates from the story The Wolf and the Children. It is also found in Chinese culture—The Girl and the Tiger; however, it is described at the level of other concepts, which confirms the genetic relationship of intercultural conflict. The nature of the extended Chinese translation testifies to the flexible structure and aesthetics of the style, in which traditions and family values play an important role, while in the English version some elements of culture are omitted due to a different mentality and structure of the language. Chinese culture is characterized by respect for elders, a tribute to traditions, and respect for people who are higher in social status. Undoubtedly, greetings in the English language carry a similar semantic load, but due to the peculiarity of its grammatical structure, omitting or transferring a greeting during translation does not harm the context of communication. Thus, it has been revealed that folk tales are a joint imprint of different cultures. The linguistic progression makes them change and adopt new information in accordance with the mentality of the people. There are three clusters of autonomous versions of the fairy tale: far Eastern, African and European; all of them are based on one common ancestor that has not been yet identified.

Manmath Narwane, Dorothy Priyanka Dorairaj, Yu-Lun Chang et al.

Zn(II) complexes bearing tris[3-(2-pyridyl)-pyrazolyl] borate (Tp^py) ligand (<b>1</b>–<b>3</b>) was synthesized and examined by spectroscopic and analytical tools. Mononuclear [Tp^pyZnCl] (<b>1</b>) has a Zn(II) centre with one arm (pyrazolyl-pyridyl) dangling outside the coordination sphere which is a novel finding in Tp^pyZn(II) chemistry. In complex [Tp^pyZn(H₂O)][BF₄] (<b>2</b>) hydrogen bonding interaction of aqua moiety stabilizes the dangling arm. In addition, solution state behaviour of complex <b>1</b> confirms the tridentate binding mode and reactivity studies show the exogenous axial substituents used to form the [Tp^pyZnN₃] (<b>3</b>). The complexes (<b>1</b>–<b>3</b>) were tested for their ability to bind with Calf thymus (CT) DNA and Bovine serum albumin (BSA) wherein they revealed to exhibit good binding constant values with both the biomolecules in the order of 10⁴–10⁵ M⁻¹. The intercalative binding mode with CT DNA was confirmed from the UV-Visible absorption, viscosity, and ethidium bromide (EB) DNA displacement studies. Further, the complexes were tested for in vitro cytotoxic ability on four triple-negative breast cancer (TNBC) cell lines (MDA-MB-231, MDA-MB-468, HCC1937, and Hs 578T). All three complexes (<b>1</b>–<b>3</b>) exhibited good IC₅₀ values (6.81 to 16.87 μM for 24 h as seen from the MTS assay) results which indicated that these complexes were found to be potential anticancer agents against the TNBC cells.

Anthony J.F. Reardon, Elham Khodayari Moez, Irina Dinu et al.

Serum perfluoroalkyl acids (PFAAs) have been linked to disruption of maternal thyroid hormone homeostasis, but results have varied between studies which we hypothesized was due to timing of the thyroid hormone measurements, variability in PFAA isomer patterns, or presence of other stressors. In a longitudinal study design, we investigated the time-dependency of associations between PFAA isomers and thyroid hormones during pregnancy and post-partum while considering thyroid peroxidase antibody (TPOAb) status and mercury (Hg) co-exposure. In participants of a prospective Canadian birth cohort (n = 494), free thyroxine (FT4), free triiodothyronine (FT3), thyroid stimulating hormone (TSH) and TPOAb were quantified in maternal plasma collected in each trimester and 3-months postpartum, and 25 PFAAs (15 linear and 10 branched) and Hg were quantified in samples collected during the second trimester. Perfluorohexane sulfonate (PFHxS) and total branched isomers of perfluorooctane sulfonate (PFOS) were positively associated with TSH in mixed-effect models, with strongest associations early in gestation. Throughout pregnancy and post-partum, PFHxS was inversely associated with FT4, consistent with elevated TSH, while Hg was inversely associated with FT3. In TPOAb-positive women, negative associations were found between PFUnA and FT4, and 1m-PFOS and TSH, supporting previous studies that thyroid disorder could increase susceptibility to PFAA-mediated hormone dysregulation. Hg did not confound associations but was a significant interaction term, revealing further positive associations between PFOS isomers (∑3m+4m-PFOS) and TSH. Higher perfluoroalkyl sulfonate exposures were associated with higher TSH and/or lower FT4, strongly suggestive that PFHxS and branched PFOS isomers are risk factors for subclinical maternal hypothyroidism. Isomer-specific analysis is important in future studies, as crude measures of ‘total-PFOS’ masked the associations of branched isomers. A concerning result was for PFHxS which had consistent negative associations with FT4 at all time points and a positive association with TSH in early pregnancy when fetal development is most sensitive to disruption. Keywords: Perfluoroalkyl acids, Perfluoroalkyl sulfonates, Perfluoroalkyl carboxylates, Thyroid hormones, Pregnancy, Longitudinal study design

Lynn Chua

Abstract Two Burmese oil paintings on zinc supports depicting portraits of royal families, dated to the early 20th century by Saya Aye and Saya Mya, showed interesting corrosion, efflorescence and soapy globules for analytical investigation prior to conservation for exhibition. The features and colours on the two paintings, one of which was in worse condition than the other, were obscured by a whitish haze. Paint rupture and losses due to corrosion of the zinc support were apparent. Using a combination of 3D digital microscopy, FTIR microscopy and SEM–EDS, the degradation, as well as the paint materials and artists’ techniques were analysed and discussed. Zinc soaps, oxalates, silicates, hydroxychlorides, carbonates, wax and mould characterized the haze. Interestingly, brown outlines in Aye’s painting appeared unusually dark. Upon analysis, this degradation phenomenon was attributed to micro-sized greenish soap globules that have developed around copper/zinc (brass) particles, causing the brown outlines to lose their intended luminosity. The other painting by Mya, in which the same brown outline was applied, did not show such formation of globules. Detection of oxalates in the corrosion of zinc support and brown outlines are discussed. This study shows the importance in understanding the artists’ materials and techniques, which have consequential effects to the degradation observed.

H. Clever, K. Kühn, P. Fietzek

Saplonţai-Pop Aniela, Moţ Augustin, Moldovan Marioara et al.

Background: The extracts of Allium cepa are known for their medical use: antioxidant, antiinflammatory, antimicrobial, fibrinolytic and antiplatelet properties. Our study aims to establish, using in vitro tests, the antiplatelet and antioxidant character, the link between them and the extract acidity, from seven varieties of A. cepa. Methodology: The qualitative and quantitative presence of polyphenols and anthocyanins in the extracts was determined using UV-Vis and HPLC. Quantitative determination of the thiosulfinates compounds was calculated using their reaction with 4-mercaptopyridine. Antioxidant character was determined using 3 methods (FC, DPPH and TEAC), and antiplatelet effect was measured by in vitro tests on platelet rich plasma obtained from human blood. Principal Findings/Results: The white variety of A. cepa has the most alkaline pH, the largest amount of thiosulfinate compounds and the most powerful antiplatelet effect, but a very small amount of flavonoids and an antioxidant effect almost nonexistent, in contrast with red variety of A. cepa which is the opposite. Conclusions/Significance: The white variety of A. cepa had very high anitiplatelet activity suggesting the potential use of A. cepa extract in treating cardiovascular diseases.