LC Sample Research Articles (Page 1)

More microscopic interfacial segregation slowers macroscopic grain growth: A case in WC-Co cemented carbides

Solar photovoltaic (PV) power generation is a major carbon reduction technology that is rapidly developing worldwide. However, the impact of PV plant construction on subsurface microecosystems is currently understudied. We conducted a systematic investigation into the effects of small-scale light stress caused by shading of PV panels and sampling depth on the composition, diversity, survival strategy, and key driving factors of soil bacterial communities (SBCs) under two vegetation restoration modes, i.e., Euryops pectinatus (EP) and Loropetalum chinense var. rubrum (LC). The study revealed that light stress had a greater impact on rare species with relative abundances below 0.01% than on high-abundance species, regardless of the vegetation restoration pattern. Additionally, PV shadowing increased SBCs' biomass by 20-30% but had varying negative effects on the numbers of Operational Taxonomic Unit (OTU), Shannon diversity, abundance-based coverage estimator (ACE), and Chao1 richness index. Co-occurrence and correlation network analysis revealed that symbiotic relationships dominated the key SBCs in the LC sample plots, with Chloroflexi and Actinobacteriota being the most ecologically important. In contrast, competitive relationships were significantly increased in the EP sample plots, with Actinobacteriota having the most ecological importance. In the EP sample plot, SBCs were found to be more tightly linked and had more stable ecological networks. This suggests that EP is more conducive to the stability and health of underground ecosystems in vulnerable areas when compared with LC. These findings offer new insights into the effects of small-scale light stress on subsurface microorganisms under different vegetation restoration patterns. Moreover, they may provide a reference for optimizing ecological restoration patterns in fragile areas.

Mitigating matrix effects for LC-MS/MS quantification of nitrosamine impurities in rifampin and rifapentine

Investigation of solute-solvent interactions of 4′-alkyl-4-cyanobiphenyl liquid crystals using Raman spectroscopy

Comprehensive two-dimensional liquid chromatography with high resolution mass spectrometry to investigate the photoelectrochemical degradation of environmentally relevant pharmaceuticals and their degradation products in water

Mayotte Island, a French department located in the Mozambique Channel, has for several years been faced with the consumption of "La Chimique" (LC), reputed (but extremely poorly documented) to be a mixture of tobacco and synthetic cannabinoid receptor agonists (SCRAs). One of the objectives of the CHASSE-MAREE protocol is to assess the composition and heterogeneity of LC products through successive LC sample collection campaigns among users. Currently underway, we present here the first analytical results (samples collected in 2022). Between September and December 2022, 80 samples were collected throughout the island over three periods: 70 in the usual form of LC (small folded papers containing a plant-like sample, mostly tobacco), 6 powders, and 4 cigarettes. Analysis was performed using liquid chromatography with high-resolution mass spectrometry. The detected substances (number of detections) included SCRAs (MDMB-4en-PINACA [35], ADB-FUBIATA [25], MDMB-INACA [16], ADB-BUTINACA [15], AFUBIATA [11], 4F-MDMD-BICA [7], CH-PIATA [14], 5C-APINACA [3], BZO-HEXOXIZID [2], and 4F-ABINACA [1]), nicotine (68), tetrahydrocannabinol (THC), cannabinol (CBN), and cannabidiol (CBD) (2), medications (amantadine [11], cyamemazine [6], and acetaminophen [3]), and a designer benzodiazepine (bromazolam [4]). The SCRAs currently in use are varied, and the market for "cooks" (those who prepare LC) is dispersed according to where and when samples are collected. These preliminary results will be supplemented by analysis of samples collected in the first half of 2023 and by an improved description of the current panorama of consumption of LC in Mayotte (mapping, effects felt and dependence, etc.).

Simultaneous quantitation of inorganic ions in oligonucleotides using mixed-mode liquid chromatography coupled with a charged aerosol detector

Large-Size Honeycomb-Shaped and Iris-Like Liquid Crystal Elastomer Actuators

An analytical method has been developed and validated for determining 107 pesticide residues in dried red pepper using LC-MS/MS. LC method, the clean-up and sample dilution processes were examined to determine their impact on reducing the matrix effects. Clean up was performed using an ENVI-CarbIITM/PSA (300/600 mg, 6 mL) SPE cartridge. In the sample dilution process, eight-fold dilution was used. In the validation of the developed method at two concentrations (0.01 and 0.1 μg/g) for 107 pesticides, 96 pesticides showed recovery rates in the range of 70.1 to 112.6%, RSDs of repeatability of ≤11.5 and 3.4%, and RSDs of within-laboratory reproducibility of ≤24.3 and 19.9%. These values fulfill the criteria of the validation guidelines for pesticide residues in Japan. It is concluded that matrix effects and low recovery rates in the process of extraction are the main factors for values that do not conform to the criteria.

ABSTRACTA transparent flexible polymer film is chemically functionalised with a bent-core liquid crystal (BCLC) compound for effective alignment of the bulk BCLC sample at the substrate–LC interface. The surface attachment was achieved via a simple procedure which involved pre-treatment of the polymer film (commercial name: over head projector film) using piranha solution followed by chemically attaching the BCLC compound through silane condensation reaction. Surface characterisation of the unmodified and BC-modified flexible films was carried out through X-ray photoelectron spectroscopy (XPS), attenuated total reflectance fourier transform infrared (ATR-FTIR) spectroscopy, contact angle (CA) and atomic force microscopy (AFM) techniques. The BC-modified flexible substrates are analysed for their efficiency to orient the bulk LC sample. Remarkably, the chemically modified polymer substrates are highly efficient in vertically aligning both the BC and rod-like LC samples at the substrate–LC interface, in comparison to their unmodified counterparts. The described method is simple, reproducible, surface modified substrates are highly stable and more importantly reusable. The demonstrated method for the alignment of BCLCs advances a step forward towards the realisation of applications proposed for these fascinating compounds.

Objective To investigate the community structure of intestinal bacteria from patients with cirrhosis and its influencing factors. Methods From 2016 to 2017, 24 patients with liver cirrhosis (the LC group) and 23 healthy family members of patients (the HC group) were enrolled at the First Hospital of Lanzhou University. A comparative analysis of the community structure of intestinal bacteria was performed using 16S rRNA gene sequencing in LC and HC groups. Combined with LEfSe analysis and NMDS analysis, the differential markers were screened and the factors affecting the intestinal community structure of subjects were studied. Results The dominant six phylum of bacteria in intestines in LC and HC groups included Firmicutes, Bacteroides, Proteobacteria, Actinobacteria, Fusobacteria and Tenericumes. However, in the LC sample, Firmicutes was significantly reduced, while Bacteroides was significantly increased. The diversity of intestinal bacteria was significantly reduced, and the Firmicutes/Bacteroides ratio was significantly decreased, suggesting a variation of the community structure in intestinal bacteria of cirrhosis patients. The LEfSe result indicated that the abundance of Enterococcus, Lactobacillales, Bacilli, and Bacteroidetes showed a significant difference in the LC sample, which may be used as potential marked bacterial groups for cirrhosis. The NMDS analysis revealed a positive relationship between the concentration of Cd and Pb and the abundance of intestinal bacteria in the LC sample. Conclusion The community structure of intestinal bacteria from patients with cirrhosis has changed. Enterococcus, Lactobacillales, Bacilli, and Bacteroidetes are potential marked bacterial groups. The concentration of Cd and Pb in the intestinal tract of cirrhosis patients may interact with the abundance and structure of bacteria, and further affect the occurrence and development of cirrhosis. Key words: Cirrhosis; Intestinal bacteria; Bacterial community structure; Influencing factor

The present study investigates the influence of InP/ZnS core/shell QDs on various parameters of Nematic LC sample 1832A, based on 4-(4-alkyl-cyclohexyl)benzene isothiocyanates and 4-(4-alkyl-cyclohexyl)biphenyl isothiocyanates. Observations recorded consist of distinguished functioning of birefringence phenomenon along with characteristic response time measurement. Further study of rotational viscosity and splay elastic constant portrays stupendous behavior strengthening the appositeness of the composites for low-charge consumable devices. The addition of 0.2 ml of core/shell QDs producing more than two times faster response and enhanced birefringence at low-temperature range can be employed in development of thermostable photonic devices. In addition, dielectric properties comprising of relative permittivity and conductivity have been reported supporting the outcome of the investigation in applicative LC-based technologies.

The finite-size effect in thin liquid crystal systems

Optically switchable and axially symmetric half-wave plate based on photoaligned liquid crystal films

Microdialysis is often applied to understanding brain function. Because neurotransmission involves rapid events, increasing the temporal resolution of in vivo measurements is desirable. Here, we demonstrate microdialysis with online capillary liquid chromatography for the analysis of 1 min rat brain dialysate samples at 1 min intervals. Mobile phase optimization involved adjusting the pH, buffer composition, and surfactant concentration to eliminate interferences with the dopamine peak. By analyzing electrically evoked dopamine transients carefully synchronized with the switching of the online LC sample valve, we demonstrate that our system has both 1 min sampling capabilities and bona fide 1 min temporal resolution. Evoked DA transients were confined to single, 1 min brain dialysate samples. After uptake inhibition with nomifensine (20 mg/kg i.p.), responses to electrical stimuli of 1 s duration were detected.

Rapid measurement of tacrolimus in whole blood by paper spray-tandem mass spectrometry (PS-MS/MS)

In this study, we present several simple but effective methods to stabilize blue phases (BPs) and investigate their possible stabilization mechanisms. An achiral mesogen monomer with a branched end group (MF-LCM) and chiral hydrogen-bonded assemblies (CHBAs) were prepared and were applied to extend the BP temperature range of a simple cyanobiphenyl compound (8CB). Increasing the achiral mesogen monomer content results in a widened BP range, which is could be due to molecular shape of the achiral MF-LCM and their interactions with the bulk Ch-LCs molecules. Meanwhile, the result demonstrates that CHBAs also have a positive influence on broadening the BP temperature range, this expansion of the BP temperature range was induced by the chiral effect and viscosity effect. Taking these two factors into account, the widest BP temperature range in the LC sample with MF-LCM and CHBAs was 13.0 °C during the cooling process. Furthermore, LC mixtures with MF-LCM and di-functional liquid crystalline monomer (C6M) were irradiated by UV light to induce polymerization. The BP temperature range was broadened obviously, and the widest BP range has been extended even up to about 41.0 °C, which results from the traditional polymer stabilization mechanism and BP polymer templating effect. These explorations provide some useful insight into the molecular design, chiral effect and polymer network towards stabilizing BP.

Earlier we observed a movement of the front of ions in the bulk of an ordered LC sample across which the driven voltage was applied [1]. This movement looked as waving zigzag curvatures in the pattern of interference strips. It was shown that behind the movable front of ions, the LC volume was getting charged. The author has found out that, in his pioneer experiments made in 1974, he observed the similar electrooptical phenomena on a single crystal of niobate-strontium-barium (NBS). Just after applying driving voltage (in a crossed electrical field crystal sample geometry) a system of curved interference strips is arising, which is evolving for the time period of about ten minutes at the driven voltage being kept constant. The evolution of the interference stripes pattern near positive, negative electrodes and in middle part of sample occurs in some different ways. At the end of evolution the system of strips disappears and the sample becomes practically homogeneous. The described process can be observed only once at the first applying of the driving voltage. This process is caused by redistribution of charges frozen at the crystallization and which are having an opportunity of the recombination at the first applying of the driving voltage. The obtained results are discussed with the possible applying the given experimental technique for solid and LCs parameters studying.

In this work, an experimental approach was used for measuring birefringence of thermotropic liquid crystal materials at different wavelengths in the visible region by using speckle interferometry. Also the values of the refractive indices were measured for these thermotropic liquid crystal materials in isotropic and liquid crystal phases at different wave-lengths. Temperature dependency of the refractive indices for each LC sample at certain wavelengths was investigated in the isotropic and in LC phases.

A microfluidic device capable of two-dimensional reversed-phase liquid chromatography-capillary electrophoresis with integrated electrospray ionization (LC-CE-ESI) for mass spectrometry (MS)-based proteomic applications is described. Traditional instrumentation was used for the LC sample injection and delivery of the LC mobile phase. The glass microfabricated device incorporated a sample-trapping region and an LC channel packed with reversed-phase particles. Rapid electrokinetic injections of the LC effluent into the CE dimension were performed at a cross-channel intersection. The CE separation channel terminated at a corner of the square device, which functioned as an integrated electrospray tip. In addition to LC-CE-ESI, this device was used for LC-ESI without any instrumental modifications. To evaluate the system, LC-MS and LC-CE-MS analyses of protein digests were performed and compared.