Mobile Liquid Research Articles

A nitrogen-specific detector for high performance liquid chromatography

We describe a nitrogen-specific detector (NSD) for aqueous mobile phase-based high performance liquid chromatography (HPLC). It is based by means of total hydrophilic organic nitrogen detection. Separated analytes are photooxidized online and converted to nitrate, followed by an ultravilet absorbance detector. It features response dependant on the product of nitrogen number in the molecule and its molar concentration, no matter what is ultravilet-absorbing or not. The HPLC equipped with NSD can quantify nitrogen-containing analytes via a sole standard of potassium nitrate for calibration. This results in identical calibration curve for all nitrogen-containing analytes, obviating individual calibration. The limit of detection of NSD is 4.3 μM N/L, and its linear range is up to 4 mM N/L.

Leak detection systems in oil and gas fields

The article is devoted to a review of methodological approaches to the localization and detection of liquid and gas leaks when using pipelines in oil and gas fields. The relevance of the issue is explained by the fact that a significant number of incidents that negatively affect the activities of oil and gas companies occur in connection with the leakage of resources in oil and gas fields. The purpose of the study is to present the state of the art of modern acoustic and infrared methods used to detect liquid and gas leaks in oil and gas fields. The author used various classifications to analyze the characteristics of the methods, allowing them to be divided into active and passive; acoustic, optical, electrical, and chemical systems methods; permanently installed and mobile liquid and gas leak detection systems. Among the considered methods for detecting liquid and gas leaks in oil and gas fields, acoustic and infrared methods are the most effective; they can be quite easily integrated into an existing liquid and gas leak detection system. Infrared and acoustic methods can also be used on pipelines, with the latter being used more often than infrared methods due to the fact that they cover very long pipelines using pinpoint liquid and gas leak detectors in oil and gas fields. More advanced concepts for leak detection systems in oil and gas fields involve a combination of several methods, for example, the study reflected the specificity of combining a magnetic and ultrasonic sensor for detecting liquid and gas leaks in oil and gas fields. Although innovative concepts continue to be developed, some oil and gas enterprises still employ methods based on manual human labor which includes examining and sampling the contents of pipelines. In conclusion, it was noted that at the present stage the practical application of several methods simultaneously in the system for detecting liquid and gas leaks in oil and gas fields is required, since each of them individually has significant disadvantages for oil and gas enterprises, which can be offset by an appropriate combination of existing methods.

Nanoparticle Analyzing Technique Review and Sub-10 nm Nanoparticle Sizing Methods Comparison

This paper provides a comprehensive review of current nanoparticle analysis methods specifically designed for sub-20 nm particles. The techniques are categorized into three main groups: ensemble (I), single particle counting (II), and separating & counting (III) methods. The study further presents a comparative analysis of test results obtained using these three categories of methods on polydisperse polymer nanoparticles. For this investigation, four different tools capable of sub-10 nm particle analysis were utilized. The techniques employed in this study include dynamic light scattering (I), atomic force microscope (II), scanning mobility liquid particle sizer (III), and cryo-electron microscopy (I). The findings indicate that, for particles larger than 8 nm, the three tools—excluding dynamic light diffraction—yield similar results. Conversely, in the small size range (<7 nm), cryo-electron microscopy consistently demonstrates reliable outcomes.

Insights into Permanent Encodings of Macroscopic Spike Patterns by Magnetic-Field-Directed Evaporative Self-Assembly from Ferrofluids.

Field-directed assembly has the potential to make large hierarchically ordered structures from nanoscale objects. Shear forces and optical, electric, and magnetic fields have been used for this purpose. Ferrofluids consist of magnetic nanoparticles hosted in mobile liquids. Though they exhibit rich structures and lattice patterns in response to an applied magnetic field, the patterns collapse when the field is removed. Recently, we adapted evaporation-induced self-assembly to obtain permanent encodings of the complex field response of magnetite nanoparticles in alkane media. The encodings are characterized by order that culminates in macrostructures comprising kinetically trapped spike patterns. The present work examines a number of variables that control pattern formation associated with this encoding. Control variables include applied magnetic field strength, magnetic field gradient, nanoparticle concentration, solvent evaporation conditions, and alkane solvent chain length. The pattern formation process is captured in six stages of evolution until the solvent host has evaporated and the pattern is permanently fixed. The macropatterns consist of hexagonal arrays that coexist with different pentagonal and heptagonal defects. The Voronoi entropy is calculated for different patterns that arise due to changes in the control parameters. Insight into order in the lattice patterns is achieved by extracting measurables like peak-to-peak spike wavelength, spike population, spike height, and base diameter from the patterns. The pattern measurables depend nonlinearly on the magnetic field gradient, solvent evaporation rate, and solvent chain length. Nanoparticle concentration does not impact the measurables significantly. Nonetheless, the results agree qualitatively with a linear expression for the critical magnetization and wavelength that explicitly contains the field gradient and surface tension.

Semiconducting CdS quantum dots as a guest in a four ring bent-core nematic medium: modified dielectric and elastic properties

The nematic phase of the bent-core family proves to be particularly fascinating due to its distinct properties in comparison to its calamitic counterpart. Here we revealed after the dispersion of semiconducting CdS QD an achiral unsymmetrical (4′-fluoro phenyl azo) phenyl-4-yl 3-[N-(4′-n-hecyloxy two hydroxybenzylidene)amino]-2-methylbenzoate (6-2M-F) a bent-core nematic (BCN) liquid-crystalline medium made of bent-shaped molecules with short cores and low bend angles. These molecules are on the cusp between conventional bent-core molecules and rod-like molecules, with characteristics somewhere in between, resembling hockey sticks. The threshold voltage dielectric permittivity and elastic constants of pure BCN have been considerably influenced by semiconductor nanoparticles. The threshold voltage of nano-disperse BCN has decreased with QD doping, and we know that the low operation voltage is one of the key considerations in the development of mobile liquid crystal display technology. Similar to other BCNs with smectic-like clusters previously described, the elastic anisotropy for 6-2M-F is negative; however, the insertion of CdS QDs causes the anisotropy to become very positive (bend elastic constant > splay elastic constant ). While the parallel component of permittivity has declined with doping, the perpendicular component of permittivity has increased, leading to a considerable reduction in dielectric anisotropy in the nanocomposite, which implies the effect on nematic ordering due to the interaction between CdS QDs and the LC molecules.

Use of plant waste in the treatment of heavy metal polluted wastewater

Introduction. Anthropogenic pollution is one of the global environmental issues of the modern world. The main approach to solving this issue is the transition to a nature-like economy of a closed cycle where the waste of one production is not accumulated but used as raw material for the other production. The article considers the possibility of using three renewable large tonnage byproducts of agro-industrial complex: technical hemp hulls, wheat straw (carbonized), and buckwheat hulls (granulated) for the manufacture of heavy metal sorbents (biosorbents). Biosorbents made of ecologically pure natural raw materials can be used for treatment of surface wastewater of urban settlements and wastewater from the territory of mining enterprises from heavy metals. The purpose of this article is to estimate the efficiency of wastewater treatment of heavy metals (in particular, Al, Cu, Fe, Pb, and Zn).
 Materials and methods. The sorbents in this study were made from agro-industrial byproducts: hemp hulls (by-product of technical hemp processing); straw (dry wheat stalks from fields in Chelyabinsk Region, crushed and carbonized); granulated buckwheat hull. The sorbate was surface wastewater urbanized area from Chelyabinsk city and acid mine drainage from the Ural region mining enterprise. Laboratory studies of the interactions occurring in the sorbent-sorbate system were carried out using the limited volume method with static sorption, wherein the pollutants were in the liquid phase and brought into contact with a static sorbent and a dynamic test, wherein the pollutants in a mobile liquid phase were filtered through a layer of sorbent.
 Results. The structure and surface composition of agro-industrial wastes such as hemp hulls, carbonized straw, and granulated buckwheat hulls (biosorbents) were studied. The obtained data confirmed the ecological safety of the studied materials. The main chemical elements in their composition are carbon, oxygen, potassium. The efficiency of sorption by the biosorbents in removing heavy metals from urban surface wastewater and mining-influenced water was determined.
 The research data showed that under static conditions, buckwheat hulls best absorb pollutants from urban surface wastewater, removing copper, iron, lead, and zinc ions from surface wastewater with 100 % efficiency. With the increase of temperature from 0 °C to 10–20 °C, the efficiency of purification also increases. An exception is the process of copper ions sorption, where the maximum efficiency is achieved at 0 °C with minimum sorbent contact time.
 Under dynamic conditions, it is more effective to use hemp hulls, also showing its efficiency in removing pollutants from acid mine drainage — 100 % of aluminum, copper, and lead ions were removed.
 Conclusions. The obtained results show that the examined agro-industrial byproducts are ecologically safe and effective sorption materials and allow extracting heavy metals (aluminum, copper, iron, lead, zinc) from urban surface and mining enterprises runoff.

Expanding the Epitranscriptomic RNA Sequencing and Modification Mapping Mass Spectrometry Toolbox with Field Asymmetric Waveform Ion Mobility and Electrochemical Elution Liquid Chromatography.

Post-transcriptional modifications of RNA strongly influence the RNA structure and function. Recent advances in RNA sequencing and mass spectrometry (MS) methods have identified over 140 of these modifications on a wide variety of RNA species. Most next-generation sequencing approaches can only map one RNA modification at a time, and while MS can assign multiple modifications simultaneously in an unbiased manner, MS cannot accurately catalog and assign RNA modifications in complex biological samples due to limitations in the fragment length and coverage depth. Thus, a facile method to identify novel RNA modifications while simultaneously locating them in the context of their RNA sequences is still lacking. We combined two orthogonal modes of RNA ion separation before MS identification: high-field asymmetric ion mobility separation (FAIMS) and electrochemically modulated liquid chromatography (EMLC). FAIMS RNA MS increases both coverage and throughput, while EMLC LC-MS orthogonally separates RNA molecules of different lengths and charges. The combination of the two methods offers a broadly applicable platform to improve the length and depth of MS-based RNA sequencing while providing contextual access to the analysis of RNA modifications.

Bioventing revisited: efficacy of enhanced biodegradation for sites with mobile LNAPL

Bioventing is a remediation technology that enhances aerobic biodegradation of petroleum-affected soil in the vadose zone by introducing oxygen to the subsurface. Bioventing was historically considered effective for decreasing petroleum hydrocarbons concentrations in soil but discounted for sites where mobile light non-aqueous phase liquid (LNAPL) accumulated in wells. While the science behind bioventing has not changed, the conceptual understanding of LNAPL depletion processes and framework for evaluating the efficacy of LNAPL remediation technologies has changed markedly since the 1990s. This shift leads to a new perspective on the utility and effectiveness of bioventing compared to other LNAPL remedial alternatives. A case study is used to illustrate that mass depletion by bioventing often outperforms hydraulic recovery over time. Biodegradation processes enhanced by bioventing deplete LNAPL constituents in mobile and residual LNAPL in the LNAPL smear zone, which means that bioventing can address a larger mass of LNAPL and may induce a beneficial composition change. Hydraulic LNAPL recovery technologies only access the mobile LNAPL and do not induce a composition change. Furthermore, for low LNAPL recoverability (transmissivity), bioventing typically uses less energy and produces less waste per unit mass of hydrocarbon removed than hydraulic recovery, making bioventing a more sustainable remedial technology.

Hydrodynamic Hysteresis and Solute Transport in Agglomerated Heaps under Irrigation, Stacking, and Bioleaching Controlling

Hydrodynamic hysteresis exists widely in agglomerated heaps with well-developed intra-pores, and it directly affects solute transports and bioleaching reaction. In this paper, the dynamic liquid retention behavior under different heap porosity and irrigation condition is quantified via a novel real-time, in-situ liquid retention characterizing system (RILRCS), and the potential effects of initial liquid retention on solute transport and leaching reaction are carefully discussed. The results show that the immobile liquid is dominant in agglomerated heaps. The ratio of immobile and mobile liquid (η) dynamically changes due to mineral dissolution and new flow path appearances. The η normally increases and mobile liquid occupies a higher proportion due to acidic leaching reactions, especially at a smaller Rg (10.32 mm) and a larger u (0.10 mm/s). The dynamic liquid retention is more sensitive to the diameter of packed feeds (Rg) and superficial flow rate (u) instead of leaching reactions. This might be because the damage of leaching reaction on minerals pores/voids is limited and cannot extensively change the potential pore channels or fluid flow paths. Based on pulse tracing and conductivity tests, we reveal that the solute resides longer under a slower u and smaller packed Rg condition, which corresponds well with desirable copper leaching efficiency. Specifically, the liquid hysteresis behavior is more obvious at a lower u (0.01 mm/s) and smaller Rg (10.32 mm). This paper gives a good reference to ascertain the liquid retention and hydrodynamic hysteresis and promote mineral leaching performance.

Comparison of refilling schemes in the free-surface lattice Boltzmann method

Simulating mobile liquid–gas interfaces with the free-surface lattice Boltzmann method (FSLBM) requires frequent re-initialization of fluid flow information in computational cells that convert from gas to liquid. The corresponding algorithm, here referred to as the refilling scheme, is crucial for the successful application of the FSLBM in terms of accuracy and numerical stability. This study compares five refilling schemes that extract information from the surrounding liquid and interface cells by averaging, extrapolating, or assuming one of the three different equilibrium states. Six numerical experiments were performed, covering a broad spectrum of possible scenarios. These include a standing gravity wave, a rectangular and cylindrical dam break, a Taylor bubble, a drop impact into liquid, and a bubbly plane Poiseuille flow. In some simulations, the averaging, extrapolation, and one equilibrium-based scheme were numerically unstable. Overall, the results have shown that the simplest equilibrium-based scheme should be preferred in terms of numerical stability, computational cost, accuracy, and ease of implementation.

A Data Set of Ion Mobility Collision Cross Sections and Liquid Chromatography Retention Times from 71 Pyridylaminated N-Linked Oligosaccharides

Determination of the glycan structure is an essential step in understanding structure–function relationships of glycans and glycoconjugates including biopharmaceuticals. Mass spectrometry, because of its high sensitivity and mass resolution, is an excellent means of analyzing glycan structures. We previously proposed a method for rapid and precise identification of N-glycan structures by ultraperformance liquid chromatography-connected ion mobility mass spectrometry (UPLC/IM-MS). To substantiate this methodology, we here examine 71 pyridylaminated (PA-) N-linked oligosaccharides including isomeric pairs. A data set on collision drift times, retention times, and molecular mass was collected for these PA-oligosaccharides. For standardization of the observables, LC retention times were normalized into glucose units (GU) using pyridylaminated α-1,6-linked glucose oligomers as reference, and drift times in IM-MS were converted into collision cross sections (CCS). To evaluate the CCS value of each PA-oligosaccharide, we introduced a CCS index which is defined as a CCS ratio of a target PA-glycan to the putative standard PA-glucose oligomer of the same m/z. We propose a strategy for practical structural analysis of N-linked glycans based on the database of m/z, CCS index, and normalized retention time (GU).

Development of a Mobile Liquid Spraying Machine for Small and Medium Scale Crop Production

Development of a Mobile Liquid Spraying Machine for Small and Medium Scale Crop Production

Effects of Water Content and Irrigation of Packing Materials on the Performance of Biofilters and Biotrickling Filters: A Review

Biofilters (BFs) and biotrickling filters (BTFs) are two types of bioreactors used for treatment of volatile organic compounds (VOCs). Both BFs and BTFs use packing materials in which various microorganisms are immobilised. The water phase in BFs is stationary and used to maintain the humidity of packing materials, while BTFs have a mobile liquid phase. Optimisation of irrigation of packing materials is crucial for effective performance of BFs and BTFs. A literature review is presented on the influence of water content of packing materials on the biofiltration efficiency of various pollutants. Different configurations of BFs and BTFs and their influence on moisture distribution in packing materials were discussed. The review also presents various packing materials and their irrigation control strategies applied in recent biofiltration studies. The sources of this review included recent research articles from scientific journals and several review articles discussing BFs and BTFs.

Thin mini-LED backlight using reflective mirror dots with high luminance uniformity for mobile LCDs.

A new mini light-emitting diode (mini-LED) backlight with reflective dots is proposed for high luminance uniformity, high contrast ratio, and low power consumption for use in mobile liquid crystal displays. The proposed backlight, comprising a small number of mini-LEDs, was verified as having high luminance uniformity and high light use efficiency, due to the optimized reflective dots, backlight thickness and light distribution of the mini-LEDs. Moreover, the light leakage to adjacent segments was reduced by cutting a slit between each segment, improving the light use efficiency per segment and suppressing halo artifacts.

Mechanism for anisotropic diffusion of liquid-like Cu atoms in hexagonal β−Cu2S

${\mathrm{Cu}}_{2}\mathrm{S}$ in its high-temperature phases is a promising candidate for thermoelectric materials with the combination of a solid S lattice and liquidlike Cu atoms in the context of the so-called phonon-liquid electron-crystal (PLEC) mechanism. The atomic dynamics associated with the high Cu mobility is a critical component in our understanding of the low thermal conductivity in these materials. Among various possible PLEC compounds that have been studied experimentally, hexagonal $\ensuremath{\beta}\ensuremath{-}{\mathrm{Cu}}_{2}\mathrm{S}$ is a unique case that exhibits anisotropic diffusion channels for Cu atoms in the presence of crystalline S layers. To unveil the diffusion mechanism for such liquidlike Cu atoms, we present first-principles molecular dynamics simulations over 50 ps for hexagonal ${\mathrm{Cu}}_{2}\mathrm{S}$ at 450 K. Quantitative analysis of the atomic radial distributions, mean-square displacements, velocity autocorrelations, and atomic trajectories is reported and confirms the liquid-solid hybrid features. Our simulations reveal the preference of threefold triangular sites by Cu atoms in the S lattice. The triangular sites in the interlayer region do not bind Cu atoms strongly, allowing them to diffuse in the horizontal direction between S layers like a mobile liquid with a calculated diffusion coefficient $\ensuremath{\sim}5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{2}$/s. The corresponding atomic trajectories have a wide spread and cannot be described by the Chudley-Elliott jump diffusion model. In contrast, Cu atoms are more strongly confined at the triangular sites within the S planes, and Cu diffusion takes place only when the atom hops out of the S layer and enters the interlayer region. This yields a 50% smaller diffusion coefficient in the vertical direction. The anisotropic diffusion channels for liquidlike Cu atoms in hexagonal $\ensuremath{\beta}\ensuremath{-}{\mathrm{Cu}}_{2}\mathrm{S}$ may provide an additional degree of freedom in designing promising systems for future energy applications.

Sulfated Polyborate, a Novel Buffer for Low pH Mobile Phase on a Nonend Capped Stationary Phase in Reverse Phase Liquid Chromatography

Background: Sulfated Polyborate, a novel inorganic material primarily designed as a catalyst, has shown properties such as high solubility in organic solvents, low U.V. cut-off, and pKa ≈2.0, which suggests its potential as a mobile phase buffer for reverse-phase liquid chromatography. Objective: This study aims to substantiate the role of Sulfated Polyborate as mobile phase buffer for reverse-phase liquid chromatographic analysis of basic drugs with high pKa values viz. Bisoprolol fumarate, Timolol maleate, Verapamil hydrochloride, and Carvedilol. Methods: Solubilities, U.V. cut-offs, and pKa of Sulfated Polyborate were first experimentally confirmed. The behaviour of Sulfated Polyborate as mobile phase buffer at pH 3.0 was ascertained by varying the buffer concentration, flow rates, and percent organic modifier for elution of the four basic drugs on a non-end capped octyl silyl (C8) column. Similarly, the study was performed with KH2PO4 as a reference buffer. The column performance and conductometric measurements ascertained the impact of Sulfated Polyborate on the stationary phase. Results: Sulfated Polyborate and KH2PO4 buffers showed correlation coefficients of 0.99 and 1.00 for analyte retention factors for variation of buffer concentration and organic modifier composition, respectively. Peak symmetries and the number of theoretical plates were improved from > 2.0 to < 2.0 and ≈1000 to ≈3000, respectively, for variation in buffer concentrations. Similar Van Deemter plots indicated equivalency of Sulfated Polyborate and KH2PO4 buffers. The column performance and conductometric measurements depicted no adsorption on the stationary phase. Conclusion: The present study demonstrates Sulfated Polyborate as a novel buffer for analytes with higher pKa on reverse-phase liquid chromatography.

Design and test of a liquid helium cryogenic system for the cooling of a superconductive single-flux-quantum circuit chip

A small-scale mobile liquid helium cryogenic system has been designed for the cooling of a superconductive single-flux-quantum circuit. The system includes a unique double inner cylinder, a “zigzag” cold energy recovery structure for the coaxial line and a special magnetic shielding structure. Experiments were conducted to test the thermal performance and the magnetic shielding efficiency of the liquid helium cryogenic system. The results show that the storage time of the liquid helium is about 5 h with a heat load of 2 W and the magnetic flux density at the chip location is about 5 nT at the temperature of 4.2 K.

Графоаналитическое определение влагосодержания подвижной жидкости в капиллярной кайме пористой среды

Графоаналитическое определение влагосодержания подвижной жидкости в капиллярной кайме пористой среды

COMPONENT COMPOSITION AND BIOLOGICAL ACTIVITY OF ESSENTIAL OIL OF LIGULARIA HETEROPHYLLA RUPR.

The object of the study – the raw material of Ligularia heterophylla Rupr., collected in 2019 in the Almaty region of the Republic of Kazakhstan. The component compositions of essential oils from the aerial and underground parts of Ligularia heterophylla Rupr., obtained by methods of microwave extraction, as well as traditional hydrodistillation, were studied for the first time. Essential oils represented as mobile liquids from light yellow to green shade with characteristic odors. The component composition was determined by chromato-mass spectrometry on an Agilent 6890 gas chromatograph equipped with a MSD 5973 mass-selective detector. Essential oils obtained by the hydrodistillation method contain mainly monoterpenes, while sesquiterpenes predominate in the essential oils obtained by microwave extraction. The antimicrobial and anti-inflammatory activity of Ligularia heterophylla Rupr. essential oil samples was studied for the first time. The essential oil from the underground part (roots) of Ligularia heterophylla Rupr., obtained by microwave extraction method, at a dose of 25 mg/kg, has a pronounced anti-inflammatory activity, comparable to the drug «Diclofenac sodiumа» in the model of acute exudative reaction.

Nucleation and critical conditions for stripe domains in monodomain nematic elastomer sheets under uniaxial loading

Liquid crystal elastomers with mobile liquid crystal moieties display unique mechanical instabilities and domain patterns in the strain-induced director reorientation. Based on a continuum mechanical model, we present a complete Lagrangian description of finite element formulation of LCEs by solving the coupled displacement and director fields within the Lagrangian scheme. The nucleation of the stripe domain and critical conditions for its formation are numerically studied for thin monodomain centimeter-sized sheets. Under orthogonal uniaxial loading tests, micrometer-sized stripe domains nucleate after loading to a critical strain at which a stress peak is observed along with a reduction in the neo-classical elastic energy. Further, we observed increase in the semisoft and the Frank elastic energy as indications of strong and heterogeneous director rotations. When the loading axis was not exactly orthogonal to the initial director, we found that the sample morphology was strongly dependent on the material and geometrical parameters. Strain-induced stripe domains could still be observed in the central region of the sample when the loading axis was nearly at right angle to the initial director. If the angle between the loading axis and the initial director was slightly deviated from the right angle, nearly uniform rotations were observed. The critical angle, beyond which strain-induced stripe domains were observed, could be very close to the right angle for samples with rather small shape anisotropy and relatively large length to width ratio. In such cases, the observation of strain-induced stripe domains was highly sensitive to any possible experimental error in orienting the loading axis at right angle, and minor deviations from the orthogonal loading condition can cause uniform rotations.