Test Solution Research Articles

A signal polarity conversion photoelectrochemical immunosensor for neuron-specific enolase detection based on MgIn2S4-sensitized CsPbBr3.

Aphotoelectrochemical (PEC) immunosensor was designed based on MgIn2S4-decorated inorganic halide perovskite CsPbBr3 combined with the signal polarity conversion strategy for neuron-specific enolase (NSE) detection. CsPbBr3 was applied as the basic photoactive material owing to its excellent optical and electronic properties, which provide a good PEC performance for sensor construction. In order to improve the stability of this perovskite, the three-dimensional flower-like MgIn2S4 with a desirable direct band gap was applied to enhance the PEC response. Also, the excellent structure of MgIn2S4 provides large surface-active sites for CsPbBr3 loaded. For enhancing the detection sensitivity of PEC immunosensor, p-type CuInS2 was used as a signal probe which fixed on detection antibody (Ab2). When the target NSE was present, the photogenerated electrons produced by CuInS2 were transferred to the test solution, and the polarity of PEC signal changes. Based on the above photosensitive materials and signal conversion strategy, the proposed PEC immunosensor showed favorable detection performance, and the lineardetection range is 0.0001 ~ 100ng/mL with a 38fg/mL of detection limit. The proposed strategy improved the adhibition of CsPbBr3 in the analytical chemistry field as well as provided a reference method for other protein detections.

Synthesis and evaluation of aromatic stationary phases based on linear solvation energy relationship model for expanded application in supercritical fluid chromatography

In the last decade, the separation application based on aromatic stationary phases has been demonstrated in supercritical fluid chromatography (SFC). In this paper, four aromatic stationary phases involving aniline (S-aniline), 1-aminonaphthalene (S-1-ami-naph), 1-aminoanthracene (S-1-ami-anth) and 1-aminopyrene (S-1-ami-py) were synthesized based on full porous particles (FPP) silica, which were not end-capped for providing extra electrostatic interaction. Retention mechanism of these phases in SFC was investigated using a linear solvation energy relationship (LSER) model. The aromatic stationary phases with five positive parameters (a, b, s, e and d+) can provide hydrogen bonding, π-π, dipole-dipole and cation exchange interactions, which belong to the moderate polar phases. The LSER results obtained using routine test solutes demonstrated that the aforementioned interactions of four aromatic stationary phases were influenced by the type and bonding density of the ligand, but to a certain extent. Furthermore, the LSER data verified that the S-1-ami-anth column based on full porous particles silica had higher cation exchange capacity (d+ value), compared to the commercialized 1-AA column (based on the ethylene-bridged hybrid particles). The relationship between the d+ value and SFC additive was quantitatively proved so as to regulate electrostatic interaction reasonably. This value was greatly increased by phosphoric acid, slightly increased by trifluoroacetic acid and formic acid, but significantly reduced by ammonium formate and diethylamine. Taking the S-1-ami-naph column as an example, better peek shape of the flavonoids was obtained after the addition of 0.1 % phosphoric acid in MeOH while isoquinoline alkaloids were eluted successfully within 11 min after adding 0.1 % diethylamine in MeOH. Combined with the unique π-π interaction and controllable electrostatic interaction, the aromatic stationary phases in this study have been proven to have expandable application potential in SFC separation.

Karakteristik Kimia Dan Organoleptik Asap Cair Tempurung Kelapa Dalam Menurunkan Cemaran Logam Timbal (Pb) Pada Ikan Cakalang (Katsuwonus pelamis)

This research aims to determine the chemical characteristics of coconut shell liquid smoke and analyze the effectiveness of using liquid smoke in reducing Pb metal contamination in skipjack tuna (Katsuwonus Pelamis). Grade 2 liquid smoke from coconut shells is produced by the Pulubala IKM center through the stages of pyrolysis and distillation. This study employs a completely randomized design (CRD) with two replications. To determine the chemical characteristics of the liquid smoke, the analyzed methods include pH measurement, phenol content, total acidity, protein content, organoleptic value, and the chelating power of heavy metal Pb with variations in the concentration of liquid smoke test solutions AC (undiluted liquid smoke), AC2, AC4, AC6, and AC10 (liquid smoke with the addition of distilled water at 2%, 4%, 6%, and 10%). The results show that the best treatment is obtained from coconut shell liquid smoke with AC concentration (undiluted liquid smoke) having the best characteristics, namely a pH value of 4, phenol content of 1.6469%, total acidity of 14.94 mg/mL, protein content of 0.6083%, and a chelating power for heavy metal Pb of 97.32%. The results of the organoleptic test indicate that overall, the highest score was obtained with a neutral value at the concentration of AC2 (liquid smoke with the addition of 2% distilled water).

Adults of Sun Coral Tubastraea coccinea (Lesson 1829) Are Resistant to New Antifouling Biocides.

Biocides used in antifouling (AF) paints, such as 4,5-dichlorine-2-n-octyl-4-isothiazole-3-one (DCOIT), can gradually leach into the environment. Some AF compounds can persist in the marine environment and cause harmful effects to non-target organisms. Nanoengineered materials, such as mesoporous silica nanocapsules (SiNCs) containing AF compounds, have been developed to control their release rate and reduce their toxicity to aquatic organisms. This study aimed to evaluate the acute toxicity of new nanoengineered materials, SiNC-DCOIT and a silver-coated form (SiNC-DCOIT-Ag), as well as the free form of DCOIT and empty nanocapsules (SiNCs), on the sun coral Tubastraea coccinea. T. coccinea is an invasive species and can be an alternative test organism for evaluating the risks to native species, as most native corals are currently threatened. The colonies were collected from the Alcatrazes Archipelago, SP, Brazil, and acclimatized to laboratory conditions. They were exposed for 96 h to different concentrations of the tested substances: 3.33, 10, 33, and 100 µg L-1 of free DCOIT; 500, 1000, 2000, and 4000 µg L-1 of SiNC; and 74.1, 222.2, 666.7, and 2000 µg L-1 of SiNC-DCOIT and SiNC-DCOIT-Ag. The test chambers consisted of 500 mL flasks containing the test solutions, and the tests were maintained under constant aeration, a constant temperature of 23 ± 2 °C, and photoperiod of 12 h:12 h (light/dark). At the end of the experiments, no lethal effect was observed; however, some sublethal effects were noticeable, such as the exposure of the skeleton in most of the concentrations and replicates, except for the controls, and embrittlement at higher concentrations. Adults of T. coccinea were considered slightly sensitive to the tested substances. This resistance may indicate a greater capacity for proliferation in the species, which is favored in substrates containing antifouling paints, to the detriment of the native species.

Overcoming False-Negative Patch Tests: A Systematic Literature Review.

Exogenous allergens, found in cosmetic products, jewelry items, antiseptics and antibacterials, plants, and solvents, can cause clinical allergic contact Dermatitis (ACD). To help identify and discern which allergen is causing ACD, clinicians use patch tests, but they can yield false-negative results at times. Examining potential reasoning for false negatives is particularly helpful when a patient's history and physical examination strongly suggest ACD, and the patch test is negative. A strong history and physical presentation suggestive of ACD warrants additional patch testing or other methods to verify a false-negative patch test result. We conducted a literature review to compile various reasonings and solutions for false-negative patch tests in suspected ACD patients. Utilizing EMBASE, Scopus, PubMed, and Google Scholars, 49 articles were included by using search terms such as "False negative patch test" or "False-negative patch test" and "allergic contact Dermatitis," or "ACD." Common factors that led to false-negative patch test results include low allergen concentration, inadequate percutaneous penetration, technique error, immunosuppressive therapy, and ultraviolet exposure. Potential solutions include using different vehicles, concentration, increasing reading time, repeating the patch test, intradermal testing, and repeat open application testing. If a false-negative patch test is suspected, then intradermal testing can be administered to ensure the specificity of the patch test result. Considering the main contributing factors and solutions to false-negative patch tests, clinicians can accurately diagnose ACD and administer proper treatment plans.

Random Testing and Evolutionary Testing for Fuzzing GraphQL APIs

The Graph Query Language (GraphQL) is a powerful language for application programming interface (API) manipulation in web services. It has been recently introduced as an alternative solution for addressing the limitations of RESTful APIs. This article introduces an automated solution for GraphQL API testing. We present a full framework for automated API testing, from the schema extraction to test case generation. In addition, we consider two kinds of testing: white-box and black-box testing. The white-box testing is performed when the source code of the GraphQL API is available. Our approach is based on evolutionary search. Test cases are evolved to intelligently explore the solution space while maximizing code coverage and fault-finding criteria. The black-box testing does not require access to the source code of the GraphQL API. It is therefore of more general applicability, albeit it has worse performance. In this context, we use a random search to generate GraphQL data. The proposed framework is implemented and integrated into the open source EvoMaster tool. With enabled white-box heuristics (i.e., white-box mode), experiments on 7 open source GraphQL APIs and three search algorithms show statistically significant improvement of the evolutionary approach compared to the baseline random search. In addition, experiments on 31 online GraphQL APIs reveal the ability of the black-box mode to detect real faults.

Insight into ion exchange behavior of LDHs: Asynchronous chloride adsorption and intercalated ions release processes

Cl− adsorption and intercalated ions release processes during LDHs are highly intricate phenomena. In this study, ion exchange performance of LDHs with specific cation interlayers and intercalated anions (CaAl–NO3-LDHs, CaAl–NO2-LDHs, CaFeAl–NO3-LDHs and CaFeAl–NO2-LDHs) were extensively investigated. The results indicate that in the presence of low chloride concentration, the intercalated anions are prematurely released due to partial dissolution of LDHs in neutral deionized water and ion exchange with OH− in alkaline simulated concrete pore solution. Therefore, Cl− adsorption of LDHs and release process of intercalated anions in LDHs are not completely synchronized. Compared to partial LDHs dissolution, the accelerating effect of OH− exchange on intercalated anion release in simulated concrete pore solution is more pronounced. Further, higher stability of LDHs in testing solutions is mainly corresponding to higher binding energy between intercalation ions and cation interlayers, thus saturated Cl− adsorption content of NO3-LDHs with high binding energy is higher than NO2-LDHs with low binding energy, and saturated Cl− adsorption content of CaAl-LDHs with high binding energy is higher than CaFeAl-LDHs with low binding energy in testing solutions.

Multi-Modal Multi-Array Electrochemical and Optical Sensor Suite for a Biological CubeSat Payload.

CubeSats have emerged as cost-effective platforms for biological research in low Earth orbit (LEO). However, they have traditionally been limited to optical absorbance sensors for studying microbial growth. This work has made improvements to the sensing capabilities of these small satellites by incorporating electrochemical ion-selective pH and pNa sensors with optical absorbance sensors to enrich biological experimentation and greatly expand the capabilities of these payloads. We have designed, built, and tested a multi-modal multi-array electrochemical-optical sensor module and its ancillary systems, including a fluidic card and an on-board payload computer with custom firmware. Laboratory tests showed that the module could endure high flow rates (1 mL/min) without leakage, and the 27-well, 81-electrode sensor card accurately detected pH (71.0 mV/pH), sodium ion concentration (75.2 mV/pNa), and absorbance (0.067 AU), with the sensors demonstrating precise linear responses (R2 ≈ 0.99) in various test solutions. The successful development and integration of this technology conclude that CubeSat bio-payloads are now poised for more complex and detailed investigations of biological phenomena in space, marking a significant enhancement of small-satellite research capabilities.

Photoelectrochemical signal polarity transition mediated by quercetin for the detection of neuron-specific enolase.

A photoelectrochemical (PEC) biosensor with a wide linear detection range was developed for the sensitive detection of neuron-specific enolase (NSE), which was achieved by applying a photocurrent polarity transition strategy mediated by quercetin. The coupling reaction between Cr(VI) and quercetin drives the signal polarity from anodic to cathodic. When only quercetin is present in the test solution, photogenerated electrons are transferred to the electrode to generate anodic photocurrent. However, in the presence of the target, the signal probe released Cr(VI), which interacted with quercetin, and the electron transfer direction was changed to achieve signal polarity conversion. Meanwhile, protoporphyrin-sensitized Bi:SrTiO3 nanocubes were used as matrix photoactive materials to provide basic photocurrent. The doping of Bi element would adjust the bandgap of SrTiO3, and the organic-inorganic composite material exhibits good photostability and chemical stability that can maintain stable photoelectric properties over a long period of time. Such a novel signal polarity transition strategy greatly broadened the sensor detection to the range of 0.00007-170 ng mL-1 and obtained a relatively low detection limit (25 fg mL-1), which greatly improved the detection sensitivity and accuracy of the biosensor.

Magnetic properties and electron oxidation state transition of immunomagnetic nanoparticles specifically captured with the target bacteria

Immunomagnetic nanoparticles (IMNPs) have been widely applied for the capture and concentration in the rapid detection of target bacteria. In this research, the focus was on studying the changes in magnetic properties changes of the IMNPs when they were attached to bacterial cells. These alterations in properties could facilitate an even rapid detection of the target bacteria and eliminate the need for culturing on plating media. The variation of magnetizing values, including saturated magnetization (Ms), remanent magnetization (Mr), coercivity force (Hc), and magnetic susceptibility (χm), was analysed through M-H loops. It was observed that the magnetizing properties of the IMNPs underwent changes based on the concentrations of Salmonella Typhimurium cells in the test solution. The correlation of this phenomenon was confirmed by the results of synchrotron x-ray absorption spectroscopy (XAS), which revealed electronic transition changes in the IMNPs after capturing the bacteria cells. Additionally, the electronic bands of the magnetite nanoparticle [Fe(II) and Fe(III)] were detected, indicating an electronic transformation between the Salmonella cells and the bound IMNPs. The XAS change was further verified using different cell types, such as Campylobacter jejuni which also showed electronic transformation after attaching to IMNPs. These findings suggest that IMNP-cell attachment triggered the change in the magnetic properties of IMNPs. Such insights could serve as valuable information for the development of novel rapid bacteria detection assays/devices using magnetic sensing techniques.

Antibacterial Analysis of Talinum triangulare Against Staphylococcus aureus and Escherichia coli

This study aims to determine whether Talinum triangulare can inhibit the growth of Staphylococcus aureus and Escherichia coli. The T. triangulare used in this research were the leaves, stems and roots. Simplicia leaves, stems and roots of T. triangulare were extracted by maceration using 96% ethanol solvent, then filtered and thickened using a rotary evaporator. Testing of T. triangulare against S. aureus and E. coli using the agar well diffusion method. The test solutions used were concentrations of 20%, 40%, 60%, 80%, 100% as well as positive and negative controls as comparisons. The positive control used amoxicillin while the negative used sterile distilled water. The results of the antibacterial activity test were shown by the formation of a growth inhibition zone (ZHP) for S. aureus and E. coli. Statistical tests using One way ANOVA followed by Post Hoc tests in the form of LSD. Research data shows that leaf extract is the most effective in inhibiting the growth of S. aureus and E. coli compared to roots and stems. The most effective concentration in inhibiting the growth of S. aureus and E. coli bacteria is 100%. The increase in concentration is directly proportional to the extent of the clear zone formed around the well. T. triangulare leaf, stem and root extracts were more effective in inhibiting S. aureus than E. coli.

Important Constituents of Heavy Water-containing Solution for Cold Storage and Subsequent Reperfusion on an Isolated Perfused Rat Liver

The University of Wisconsin (UW) solution is the most effective preservation solution currently used; however, to safely use expanded-criteria donor grafts, a new cold storage solution that alleviates graft injury more effectively is required. We prepared a heavy water (D2O)-containing buffer, Dsol, and observed strong protective effects during extended cold storage of rat hearts and livers. In the current study, we modified Dsol (mDsol) and tested its efficacy. The aim of the present study was to determine whether mDsol could protect the rat liver more effectively than the UW solution and to clarify the roles of D2O and deferoxamine (DFX). Rat livers were subjected to cold storage for 48 hours in test solutions: UW, mDsol, mDsol without D2O or DFX (mDsol-D2O[-], mDsol-DFX[-]), and subsequently reperfused on an isolated perfused rat liver for 90 minutes at 37°C. In the UW group, the liver was dehydrated during cold storage and rapidly expanded during reperfusion. Accordingly, the cumulative weight change was the highest in the UW group, together with augmented portal veinous resistance and ALT leakage and decreased oxygen consumption rate and bile production. These changes were significantly suppressed in the mDsol-treated group. In the mDsol-D2O(-) and mDsol-DFX(-) groups offered partial protection. In conclusion, mDsol appeared to be superior to the UW solution for simple cold storage of the rat liver, presumably due to improved microcirculation in the early phase of reperfusion. Both heavy water and deferoxamine are essential for alleviating seamless organ swelling that occurs during cold storage and subsequent reperfusion.

IMPROVEMENT OF TECHNOLOGICAL STAGES IN BEEKEEPING WITH DISINFECTION MEASURES

Disinfection is a very important technological measure, which is carried out to combat infectious diseases of bees and prevent contamination of beekeeping products with harmful microorganisms. The disinfection procedure is very complex, and its effectiveness depends on a large number of factors: the spectrum of the disinfectant, the method of application, the concentration of the disinfectant, the exposure time, and the properties of the environment to be disinfected. Active components of disinfectants usually affect the metabolism of microorganisms. For disinfection in beekeeping, we can use iodine preparations, bases, acids, quaternary ammonium compounds, oxidizers (hydrogen peroxide, peracetic acid). Effective chemical disinfectants are a warm solution of sodium hydroxide, oxidizers, so these disinfectants are most often used in beekeeping. However, the negative properties of these disinfectants should also be considered. There is no perfect disinfectant. Because of the toxicity and other harmful effects of disinfectants, and often their ineffectiveness, physical methods of disinfection should be implemented whenever possible. The article presents the results of studies of such disinfectants as Septox, PHMG – HC and Crystal-700 in concentrations of 0.25%, 0.5%, 1.5%, as well as a comparative description of their effectiveness during “in vitro” disinfection on test objects (glass, veneer, wax) contaminated with spores of Paenibacillus larvae subsp. larvae and Ascosphaera apis. Test controls were: No. 1 – sterile physiological solution; No. 2 – Desvax (4% formaldehyde solution with 0.05% DMSO), a drug approved for disinfection of bee inventory in Ukraine (Deklaratsiinyi patent 61387A, 2003, Rudenko, 2012). The test objects were immersed in the test solutions and kept for 3, 9, 18 hours. To determine the intestinal toxicity, the test substances were fed to bees and the time and number of dead individuals were monitored. According to the results of the sanitary and hygienic assessment of individual indicators of chemical disinfectants, the best disinfecting properties were demonstrated by 1.5% solutions of polyhexamethyleneguanidine hydrochloride, sodium hypochlorite and Crystal-700, which are environmentally safe, non-toxic, non-volatile, non-aggressive towards metals, plastics, wood, convenient to use. They can be recommended for long-term antiseptic protection, preventive, forced, current and final disinfection for bacterial, fungal and viral infections.

Procedure for a standardized preparation of skin prick test solutions for the diagnosis of occupational type I allergies in the absence of commercial extracts.

In order to ensure valid diagnostics for occupational test allergen solutions despite the ongoing reduction in the availability of commercial test extracts, a plan B was initiated for the possible production of skin prick test (SPT) solutions in public pharmacies. For important occupational allergen sources (wheat and rye, storage mites, animal epithelia, mold material) laboratory extraction methods were analyzed in comparison to pharmacy compatible extraction methods regarding protein quantity and quality in SDS-PAGE combined with silver staining. Subsequently, using the example of bovine epithelia, adapted extraction procedures as well as in-process and final product controls were transferred to a public pharmacy. Allergen sources with a high protein content, such as wheat and rye grains as well as storage mites, showed good comparability of the extractable protein quantity and protein pattern, regardless of the applied extraction method. In contrast, allergen source materials with a low total protein content, such as animal epithelia and molds, can benefit from laboratory extraction conditions such as mechanical disruption and specific buffer additives. In the qualitative protein silver staining, characteristic protein patterns were identified for each allergen source. Depending on the extraction method, only minor differences in total protein patterns were observed in animal epithelia and molds. Using source materials from two suppliers, the resulting allergen extracts displayed clear differences in protein content in storage mites and quantitative and qualitative differences in molds. A practical preparation attempt of SPT solutions in a public pharmacy was successful. SPT solutions prepared with adapted pharmacy extraction methods showed a comparable protein and Bos d 2 allergen content and equivalent qualities in the protein pattern compared to a previously available commercial SPT solution. Accordingly, it can be assumed that standardized SPT solutions with sufficient allergen quality for occupational allergen sources can be prepared in public pharmacies if certified allergen sources with appropriate protein content are available.

Analysis of Factors Related to Variation in Dissolution Profiles Estimated from Continuously Conducted Dissolution Tests of Generic Products.

The development of generic pharmaceuticals involves a bioequivalence study to ensure the therapeutic equivalence of the test formulation to the original innovative product. The formulation characteristics of generic products are expected to be maintained in the long term after approval. This study analyzed the factors contributing to the changes in the dissolution profiles of approved products during their life cycles. Cumulative data on the dissolution similarity of 1675 products of 127 ingredients tested by official laboratories in Japan were assessed according to Japanese bioequivalence guidelines with slight modifications. The products showing dissimilarities in dissolution profiles were analyzed for reporting year, therapeutic category, co-development, physical properties of the active pharmaceutical ingredient (API), and suspected reasons for dissolution change. The increase in the number of dissimilar products is related to the co-development of generic products. Although the solubility of the API was not associated with the dissolution change in the analysis of the total dissolution data, control of the API particle size is suggested to be important for drugs with poorly soluble APIs. Additionally, a risk factor for dissolution changes in the test solutions at a certain pH was the presence of acidic or basic residues. These results indicate the importance of proper development through a thorough evaluation of the formulation and process factors affecting the dissolution properties throughout the product lifecycle.

Visualizing flow dynamics and restart of Carbopol gel solutions in tube and parallel-plates geometries with wall slip.

The present study examines the impact of slip in Carbopol solutions during the restart flow in pipelines utilizing in situ visualization techniques. Rheological tests were conducted using smooth and hatched parallel plate geometries to obtain the rheological characteristics of the solutions. The behavior of the solutions in the creep tests is compared with those in the experimental unit. Three flow regimes were identified through rheological and experimental setup tests: non-flow, slip, and yielded. The slip regime allowed the establishment of a slip static yield stress value, indicating significant deformation states, and a restart pressure decrease of about 61% when compared to the static yield stress. The flow dynamics under the wall slip effect is captured by velocity profiles, velocity contour maps and velocity gradient. Transient correlations of the scaling law type were determined, with wall slip in proportion to the velocity gradient and wall shear stress. Additionally, the concentration of viscoplastic material in the solution increased the scaling law index. This research seeks to provide valuable findings by quantifying the effects of apparent wall slip through in situ measurements. Such insights are crucial for designing and managing pipeline transport systems that handle yield stress fluids, applicable across various industries including cosmetics, food processing, and the production of waxy oils.

"ЛАБОРАТОРИЯ НА ЛАДОНИ": СОЗДАНИЕ МОБИЛЬНОГО ПРИЛОЖЕНИЯ ДЛЯ УДОБНОГО ДОСТУПА К ОБОРУДОВАНИЮ

This paper presents the results of research and development of a mobile application called "Laboratory in the palm of your hand" in the format of a library; discusses the relevance and importance of mobile applications in the modern world, especially in the educational process; describes the growing popularity of smartphones, their functionality and potential in learning; discusses the advantages of mobile learning and examples of its application in technical universities. The specifics of approaches to the development of mobile applications are touched upon. Various Android development tools are discussed, including Android Studio. Android Studio is a widely used development platform focused on creating mobile applications for Android. It offers a complete solution for application design, debugging and testing. Currently, Android Studio is recognized as one of the most effective tools for creating mobile applications.The preferred choice for developing applications for Android is the Kotlin programming language. The history of its appearance is briefly described. The main capabilities and characteristic features are described. It offers a more modern and intuitive approach to programming, making it an attractive choice for developers. Particular attention is paid to the concept and process of creating the application interface; its functionality, advantages and practical benefits for use by students for educational purposes are described. It is indicated that the presented approach to developing the application will provide students with easy access to the necessary information about the biotechnological equipment of the laboratory and will help them study and apply knowledge in real conditions.

Влияние активированного угля на эффективность сорбционного выщелачивания золотосодержащих руд (на примере обогатительной фабрики ГОКа «Кубака»)

Activated granular coal is widely used in processing plants, both in Russia and abroad. There are two problems at Kubaka mining and processing plant (MPP) during hydrometallurgical processing of gold-containing raw materials: loss of coal during sorption due to partial abrasion, decrease in sorption properties and, as a result, deterioration of coal quality as a result of clogging of pores with dissolved compounds in the pulp. This in turn leads to a decrease in the efficiency of sorption leaching of gold-bearing ores and an increase in the cost of gold. The aim of the study is to improve the quality of activated carbon of the GOLGCARB 207C 6X12 brand based on the use of reduction processes in order to increase the sorption capacity. Research objectives are as follows: development of a research methodology; determination of parameters of changes in the kinetic properties of activated carbon; step-by-step assessment of changes in the properties of activated carbon in the technological process; identification of the effect of coal treatment with alternative reagents (NaOH, hydrochloric acid, sulfuric acid, lime) on improving the quality of activated carbon. The object of the study is activated carbons of the GOLGCARB 207C 6X12 brand used at the Kubaka MPP (Magadan region). Research methodology and methods are as follows: a comprehensive methodology for the study of activated carbon, laboratory studies and pilot tests. The effect of activated carbon on the efficiency of sorption leaching of gold-bearing ores in laboratory conditions with the approbation of a new technological solution in semi-industrial tests has been studied. The effect of acid treatment and reactivation of coal on its sorption properties has been experimentally proven. Optimal conditions for cleaning the pores of coal from impurities of organic, carbonate and sulfur-containing compounds and an increase in sorption activity were achieved by acid treatment (replacement of hydrochloric acid with sulfuric acid) and pH control.

Constructing a zero leak landfill cell

Engineered landfill barriers are the last line of defence in protecting precious groundwater resources from contamination. A landfill cell without any leaks at the conclusion of construction is the exception rather than the rule. From design to materials testing to installation practices and contractor care, all of these elements contribute to both the short and long-term integrity of the lining system. Electrical leak location (ELL) methods can be used to detect leaks in installed landfill cells after construction so that leaks can be repaired before a landfill cell begins filling operations. However, the thorough testing of landfill cells using ELL can be complicated by their complex configuration. The dipole method, employed after cover material placement, requires electrical isolation of the cover material, which is difficult to achieve with a landfill expansion cell configuration. Additionally, employing only this type of testing can leave the tie-in area untested, which is a critical area prone to damage. This paper provides solutions for complete landfill expansion cell testing, including a relatively new testing methodology (ASTM D8265, [1]), which provides protocol for verifying that a geomembrane has been successfully installed with no leaks. A case study is included to show how ASTM D8265 can be used to provide documentation of a zero-leak condition of a landfill cell after construction. Common elements of design, geomembrane installation, and quality assurance are discussed in order to provide a road map of how to reach a zero-leak condition at the end of a landfill expansion cell construction project. This paper can be used as a guide to constructing a zero-leak landfill cell using state-of-the art construction practices and ELL testing methodologies.

Dual series solution for the standardized ISRM Brazilian disc test modelled as an advancing contact problem

A new analytical solution is found for the stress and displacement fields in a standardized ISRM Brazilian disc test with curved jaws, based on the solution of a set of dual trigonometric series. The disc is assumed to be linear elastic and isotropic and in frictionless advancing contact with the two jaws assumed as rigid, under plane stress loading conditions. Use is made of the Michell solution for an elastic disc in polar coordinates, whose coefficients are found by imposing the mixed boundary conditions along the disc rim, both along the free surface and the contact region. The problem is first reduced to a set of dual trigonometric series and then to a linear system of infinite equations, which is solved by truncation. The non-linear relations providing the contact angular extent and pressure distribution in terms of the applied load or jaw displacement, consequent to the progressive advance of the contact, are derived by using an inverse method. The obtained results are validated by comparison with previous theoretical and experimental results available in the literature. The study indicates that the method of dual series is simpler and more straightforward as compared to the analytical methods proposed in the literature for treating the Brazil disc test as an advancing contact problem.