Disk Technique Research Articles

In-plane thermal anisotropy of natural cork and its variability

This study investigates the natural cork thermal anisotropy and its variability using plane slice samples of 1.4 mm thickness, cut along the principal radial, longitudinal, and tangential directions, from bark previously treated for cork stoppers production. Heating was pointwise applied to the rear face using a copper needle coupled to a Peltier element, while an in-plane thermographic technique monitored temperature evolution on the front surfaces using a Flir SC5650 infrared camera. Thermal diffusivity measurements yielded values of 0.172 ± 0.038 mm2/s (radial), 0.161 ± 0.022 mm2/s (longitudinal), and 0.160 ± 0.027 mm2/s (tangential). Additionally, a volumetric heat capacity of 0.25 MJ/(m3·K) was determined using the Hot Disk technique. This information enabled the calculation of thermal conductivity, ranging from 0.033 to 0.048 W/(m·K). Findings align with existing literature, which reports thermal diffusivity between 0.08 and 0.24 mm2/s and thermal conductivity between 0.035 and 0.045 W/(m·K). This study contributes valuable insights into the thermal properties of natural cork and their orientation-dependent variability.

Evaluation of extended-spectrum β-lactamase production and plasmid-mediated quinolone resistance in Escherichia coli isolated from raw milk

This study aimed to determine the antibiotic resistance and extended-spectrum β-lactamase production profiles of Escherichia coli isolates obtained from raw milk samples. To this end, the study used a chromogenic-based culture method, MALDI-TOF-MS, 16S rRNA gene sequencing, disc diffusion, and combined disc techniques. PCR was also performed to detect ESBL (blaSHV, blaTEM, and blaCTX-M), quinolone (qnrA, qnrB, and qnrS) genes, and the presence of class I integrons. A total of 47 (78.33%) E. coli isolates were identified by morphological, biochemical, and molecular tests. All isolates exhibited susceptibility to gentamicin and tobramycin. Resistance rates to different antibiotics were observed as follows: ampicillin, 51.06%; nalidixic acid, 23.40%; trimethoprim/sulfamethoxazole, 17.02%; meropenem, 14.89%; ceftazidime, 8.51%; cefotaxime, 8.51%; piperacillin-tazobactam, 4.25%; aztreonam, 4.25%; imipenem, 4.25%; and levofloxacin, 2.12%. ESBL production was positive in 3 (6.38%) of the isolates. Bla genes were detected in 11 isolates (blaSHV = 9 [19.14%], blaTEM = 4 [8.5%], and blaCTX = 3 [6.38%]). The qnrB, qnrS, and qnrA genes were found in 5 (10.63%), 4 (8.51%), and 1 (2.12%) isolates, respectively. The intI1 gene was detected in 14 (29.78%) isolates.

A new test section made via additive manufacturing to perform local heat flux measurements

Recent advancements in the field of additive manufacturing have enabled the realization of products that were previously almost unattainable. In the field of heat transfer, the production of heat exchangers through additive manufacturing is promising because it allows for the creation of more compact heat exchangers that can be tailored to specific requirements with optimized and complex geometries. However, also heat transfer devices that must be specifically realized for heat transfer research purposes can benefit from the characteristics of the additive manufacturing technology. This paper presents an innovative test section created through additive manufacturing technology with the aim to investigate two-phase heat transfer of refrigerants inside a 2.9 mm internal diameter channel. Water is used as a secondary fluid to reject/extract the heat. As a first step, a CFD analysis was performed to design a special geometry for the test section allowing a local measurement of the heat transfer coefficient along the channel. The test section was realized with the DMLS (Direct Metal Laser Sintering) technology using the AlSi10Mg alloy. Despite the benefits introduced by this manufacturing process, DMLS technology can lead to anisotropy in the thermal conductivity of the test section material. Thus, cylindrical samples were produced by DMLS with different building orientations to perform specific measurements of the thermal conductivity by using the Hot Disk technique. Preliminary local heat transfer coefficients were measured with refrigerant R1234ze(E) during condensation at 40 °C saturation temperature and mass flux 150 - 200 kg m−2 s−1. Experimental heat transfer results are compared against predictions obtained from a correlation available in the literature.

The Antibacterial Activity of Novel Bacteriophages and the Emergence of Bacterial Resistance to Phage Infections: An In Vitro Study

The emergence of bacteria resistant to bacteriophage (phage) infection may compromise the success and effectiveness of phage therapy. The aim of this study was to evaluate the in vitro antibacterial activity of five novel phages, as well as the emergence of bacterial resistance to phage infections. The antibacterial activity of lytic phages was evaluated against standard strains of Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 25927), Enterococcus faecalis (ATCC 29212) and Staphylococcus aureus (ATCC 6538). Phages were initially grown in the presence of host bacteria in an exponential growth phase, then purified and titrated. In a second exposure, 20 μL of each phage was inoculated with 106 CFU/mL of P. aeruginosa/E. coli/E. faecalis/S. aureus, separately. In a third exposure, resistant colonies were isolated, cultivated and exposed again to the phages. Bacterial colonies resistant to phage infection after the third exposure were evaluated for their susceptibility profile to different antibiotics via the diffusion disk technique. The diameters of the inhibition halos were evaluated with Image J software (version 1.54g) and the definition of the susceptibility profile to antibiotics was determined according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. In addition, fourteen cocktails with different phages were formulated to evaluate the emergence of a bacterial resistance to phage infections. The phages exhibited specificity for P. aeruginosa and did not infect E. coli, E. faecalis and S. aureus. The presence of bacterial colonies resistant to phage infection in the three successive exposures was identified, and the bacterial resistance to phage infection was confirmed in all phages titrated at 108 PFU/mL, in four phages titrated at 1010 PFU/mL and in one phage titrated at 1013 PFU/mL. The development of a resistance to infection by phages (~108 PFU/mL) did not change the susceptibility profile of P. aeruginosa to antibiotics and, when evaluating the emergence of a resistance to infection by phage cocktails (~108 PFU/mL, ~1010 PFU/mL, ~1013 PFU/mL), bacterial resistance to phage infection was confirmed in all cocktails with phages titrated at 108 PFU/mL, in ten cocktails with phages titrated at 1010 PFU/mL and in seven cocktails with phages titrated at 1013 PFU/mL. In conclusion, the presence of resistant P. aeruginosa colonies to phage infection after successive exposures was evidenced, although some phages at title ~1010 PFU/mL and ~1013 PFU/mL were effective in inhibiting the growth of resistant colonies. The development of resistance did not change the susceptibility profile of P. aeruginosa to antibiotics. Variants of P. aeruginosa that were resistant to phage infection were isolated and their resistance to infection via the phage cocktail was demonstrated regardless of the viral titer, although some cocktails at title ~1010 PFU/mL and ~1013 PFU/mL were effective in inhibiting the growth of resistant colonies. Despite the emergence of bacterial variants resistant to phage infection, new studies involving the applicability of phages in the control of infections must be conducted.

Effect of Guava Leaf Extract on Aeromonas Hydrophila Bacteria

Guava leaves (Psidium guajava L.) contain terpenoids, alkaloids, flavonoids, saponins and tannins, which are believed to have antibacterial properties against Aeromonas hydrophila. Aeromonas hydrophila bacteria are bacteria that are pathogenic and cause systemic disease. This research was conducted to determine the effectiveness of guava leaves in inhibiting Aeromonas hydrophil bacteria. The method used in the antibacterial activity test was the diffusion method using the paper disc technique. The results of the One-Way ANOVA test at the 5% level and followed by the Tukey test showed that the effective inhibitory concentration was 7900 ppm with a moderate antibacterial category.

Inhibition Test of Ethanol from Extract Mangosteen Leaves (Garcinia mangostana L.) as an Acne Antibacterial

A prevalent global infection that manifests frequently in Indonesia. An example of an infectious disease that is commonly encountered during adolescence is acne (Acne vulgaris). Antibiotics can be used to treat acne; however, their misuse can lead to the development of resistance; therefore, we are searching for inexpensive, readily available alternatives that are also secure. Mangosteen leaves (Garcinia mangostana L.)Â are one alternative to synthetic ingredients when it comes to the treatment of acne. Mangosteen leaves comprise xanthone derivative compounds that exhibit significant biological activity, including antioxidant, antibacterial, and antimicrobial properties. Therefore, this this study aimed to ascertain the inhibitory power of an ethanol extract derived from mangosteen leaves in order to determine its antibacterial activity against Staphylococcus epidermidis bacteria. Additionally, the compound content of the ethanol extract of mangosteen leaves was determined. The inhibition test was conducted by utilizing the paper disc technique, while the extraction method employed the maceration method. As indicated by the phytochemical screening test results, simplicia and ethanol extract of mangosteen leaves were found to contain steroids/triterpenoids, alkaloids, flavonoids, saponins, and tannins. The inhibition test outcomes against Staphylococcus epidermidis bacteria revealed the following: a diameter of 3.3 mm for bacteria at a concentration of 20%, 9.4 mm for bacteria at 40%, 10.4 mm for bacteria at 60%, 12.9 mm for bacteria at 80%, and 13.2 mm for bacteria at 100%

Resistance to antibiotics in clinical isolates of Escherichia coli producing and non-producing Extended Spectrum Betalactamases (ESBL) obtained from urine cultures in patients with urinary tract infection.

Background: Escherichia coli is a bacterium that is part of the normal biota of the human being, but under certain conditions it can produce diseases such as gastrointestinal and urinary tract infections for which is the main responsible. Enterobacteriaceae such as Escherichia are extended spectrum betalactamases (ESBL) producers, which makes their treatment difficult due to a high rate of resistance to antibiotics.Aim of the study: Identify resistance patterns against various antibiotics in Escherichia coli producers and non-producers of extended spectrum beta-lactamases in urinary infections in a population of the Toluca Valley, MexicoMaterial and methods: 155 samples were collected from patients with suspected urinary tract infection without exclusion criteria such as age or gender. Automated equipment was used for the identification of the etiological agent and sensitivity tests. For the determination of ESBL, the double disc technique was used.Results: 35 strains of Escherichia coli were obtained, of which 45.72 % have ESBL, these strains show 100 % resistance to betalactams, as well as high resistance to quinolones and tetracycline ranging from 70 to 100 %. On the other hand, the resistance shown by non-ESBL producing strains is variable both for betalactams and for other antibiotics.Conclusion: Treatment for urinary tract infections has become increasily difficult due to the high rate of resistance to antibiotics, mainly ESBL-producing strains such as the E coli strains in the present study. Where high rates of resistance to different antibiotics used in clinical practice are shown.

Antibiocompetent and bacteriocidal relevance of ascorbic acid on coliforms isolated from feces of apparently healthy students in Rivers Nigeria

In recent times, Ascobic acid has been discovered to posses antibiocidal potential against various bacterial strains that has been resistant which is in sharp contrast as it was previously regarded as potential antioxidant especially as it is thought to reduce oxygen radicals both in vivo and in vitro biochemical processes. This study investigates the anti-biocompetent and bacteriocidal relevance of ascorbic acid on Staphylococcus aureus, Escherichia coli, and Proteus mirabilis recovered from the apparently healthy student feces at Madonna University. Standard microbiological methods were applied for the isolation of fecal coliforms using sterile blood agar, mannitol salt agar and eosin methylene blue (EMB) agar plates. The agar diffusion disc technique was used to determine an ascorbic acid fortified antimicrobial susceptibility testing of test bacteria at various concentrations varying from 0.167g/ml to 1.0g/ml, while their mean values were compared using one-way analysis of variance. The results revealed that Proteus mirabilis were resistant to the various ascorbic acid concentrations, whereas S. aureus and E. coli were susceptible to various ascorbic acid concentrations. An ascorbic acid content (g/ml) changes/shift (at p < 0.05) the zones of inhibition (mm) of the isolates (E. coli and S. aureus) Such observed antibacterial potential suggests that ascorbic acid may be applied in the treatment of enteric or coliforms infections associated with E. coli and Staphylococcus aureus.

Glaucoma Classification Using Enhanced Deep Transfer Learning Models with Hybrid ROI Cropped Optic Disc Technique

Glaucoma Classification Using Enhanced Deep Transfer Learning Models with Hybrid ROI Cropped Optic Disc Technique

Specific heat and excess heat capacity of grout with phase change materials using heat conduction microcalorimetry

Microencapsulated phase-change-materials (PCMs) incorporated in cementitious grout can be used as a source of energy in an underground thermal energy storage system. Differential scanning calorimetry (DSC) is a widely used technique to measure the latent heat or specific heat of PCM-embedded cementitious materials. However, using milligram sample sizes (as required by DSC) of a cementitious material fails to represent the actual scale of cementitious components. This is the reason why, in the present paper, non-isothermal heat conduction microcalorimetry (MC) was evaluated as a tool for determining the thermal properties of PCM-embedded grout as well as pure PCM (three PCMs were used). An MC experimental protocol (using both single and 5–6 temperature cycles) was developed and used to measure latent heat and melting and crystallization temperatures, which were in good agreement with those reported for pure PCMs by the producers. In addition, the specific heats of the PCM-containing grout also agreed with measurements using the hot disk technique. Overall, the results show that the MC technique can be used as a potential standard method in determining thermal processes in complex systems, such as in PCM-embedded cementitious systems, where a large sample size is needed to represent the material.

Variation in Susceptibility to Downy Mildew Infection in Spanish Minority Vine Varieties.

Downy mildew is one of the most destructive diseases affecting grapevines (Vitis vinifera L.). Caused by the oomycete Plasmopara viticola (Berk. and Curt.) Berl. and de Toni, it can appear anywhere where vines are cultivated. It is habitually controlled by the application of phytosanitary agents (copper-based or systemic) at different stages of the vine growth cycle. This, however, is costly, can lead to reduced yields, has a considerable environmental impact, and its overuse close to harvest can cause fermentation problems. All grapevines are susceptible to this disease, although the degree of susceptibility differs between varieties. Market demands and European legislation on viticulture and the use of phytosanitary agents (art. 14 of Directive 128/2009/EC) now make it important to know the sensitivity of all available varieties, including minority varieties. Such knowledge allows for a more appropriate use of phytosanitary agents, fosters the commercial use of these varieties and thus increases the offer of wines associated with different terroirs, and helps identify material for use in crop improvement programmes via crossing or genetic transformation, etc. Over 2020-2021, the susceptibility to P. viticola of 63 minority vine varieties from different regions of Spain was examined in the laboratory using the leaf disc technique. Some 87% of these varieties were highly susceptible and 11% moderately susceptible; just 2% showed low susceptibility. The least susceptible of all was the variety Morate (Madrid, IMIDRA). Those showing intermediate susceptibility included the varieties Sanguina (Castilla la Mancha, IVICAM), Planta Mula (Comunidad Valenciana, ITVE), Rayada Melonera (Madrid, IMIDRA), Zamarrica (Galicia, EVEGA), Cariñena Roja (Cataluña, INCAVI), Mandrègue (Aragón, DGA) and Bastardo Blanco (Extremadura, CICYTEX). The highly susceptible varieties could be differentiated into three subgroups depending on sporulation severity and density.

The Effect of Heat Treatment on Wear Properties of Ni-B-CNT Electroless Coating with Different Carbon Nanotube Concentration on AISI 4340 Steel

Study wear resistance for heat treatment of Ni-B-CNT electroless coatings. Different concentrations for CNT (0 ,0.35 and 0.7 g/l Ni-B-CNT composite coatings deposition on 4340 steel. After the procedure of coating, all samples were heat treatment. The test wear of a coating was valued with pin on disk technique. Preparation of Ni–B–CNT electroless coatings are with using nickel chloride in alkaline bath, borohydride and Multi walled carbon nanotubes. characterization with FESEM, micro hardness, XRD and surface roughness. Study for surfaces of worn with EDS and FESEM. Micro hardness results are show that the larger hardness1010 HV is gained by heat treatment for coating (Ni-B- 0.35 g/L CNT) because of concentration CNT caused structure conversion for coating Ni-B from amorphous to crystalline. Also, CNT prevent maximum heat production and decrease of the friction coefficient during test wear. CNT aggregation was noted result the presence for more particles (Ni-B - 0.7g/l CNT) that occur create roughness and also lead to increase in rate of wear because of big particles with weakly joined in matrix of Ni.

Hybrid materials based on chitosan functionalized with green synthesized copper nanoparticles: Physico-chemical and antimicrobial analysis

Recently, the development of materials with antimicrobial properties has become a challenge under scrutiny. The incorporation of copper nanoparticles (NpCu) into a chitosan matrix appears to represent a viable strategy to contain the particles and prevent their oxidation. Regarding the physical properties, the nanocomposite films (CHCu) showed a decrease in the elongation at break (5 %) and an increase in the tensile strength of 10 % concerning chitosan films (control). They also showed solubility values lower than 5 % while the swelling diminished by 50 %, on average. The dynamical mechanical analysis (DMA) of nanocomposites revealed two thermal events located at 113° and 178 °C, which matched the glass transitions of the CH-enriched phase and nanoparticles-enriched phase, respectively. In addition, the thermogravimetric analysis (TGA) detected a greater stability of the nanocomposites. Chitosan films and the NpCu-loaded nanocomposites demonstrated excellent antibacterial capacity against Gram-negative and Gram-positive bacteria, proved through diffusion disc, zeta potential, and ATR-FTIR techniques. Additionally, the penetration of individual NpCu particles into bacterial cells and the leakage of cell content were verified by TEM. The mechanism of the antibacterial activity of the nanocomposites involved the interaction of chitosan with the bacterial outer membrane or cell wall and the diffusion of the NpCu through the cells.These materials could be applied in diverse fields of biology, medicine, or food packaging.

Detection of Extended Spectrum Beta-Lactamase (ESBLs) among Urinary Tract Patients in Khartoum State, Sudan

Background: Many different organisms can cause urinary tract infections, but Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Enterococcus faecalis, and Staphylococcus saprophyticus are the most prevalent ones. 60% of all antibiotics used to treat infectious diseases around the world are beta-lactam antibiotics, one of the main classes used to fight gram-negative and gram-positive bacteria. Objective: The purpose of this study is to detect and isolate Extended-Spectrum Beta-Lactamases (ESBLs), which are responsible for urinary tract infections, as well as check for any potential medication resistance. Materials and Methods: The gram stain technique and biochemical assays were used to identify 100 urine samples from Khartoum state hospitals based on their cultural characteristics and morphological appearance. Using the disk diffusion method, the isolates were tested for antimicrobial susceptibility to third-generation cephalosporins (Cefotaxime, Ceftazidime, and Ceftriaxone). The Combination Disk Technique (clavulanic acid+third-generation cephalosporins) was used to inoculate the bacterial isolates to demonstrate their capacity to create ESBL. In comparison to non-ESBL producers, the ESBL producers were assessed. Results: E. coli, Klebsiella, S. aureus, Proteus, and Pseudomonas were among the microorganisms isolated from UTI patients. 61% of the participants in this study were female, whereas 39% were male. E. coli has an increased frequency among isolated bacteria, as it presented in 46% of urine cultures, followed by pseudomonas and Klebsiella, each with a 22% frequency. Growth of the majority of the bacteria was found among females more frequently than males, and it also seems to be among older age patients than younger. Amoxyl alone and in combination with Clavulanic Acid (AAMC) was the most medicine that bacteria were resistant to (76%), but Ceftriaxone (CTR) has higher sensitivity (45%) and resistance (50%). The growth of the bacteria in the media of antibiotics was sorted into sensitive, intermediate, and resistant. Conclusions: Tested antibiotic resistance was higher for AAMC than for CTR, which is typically taken without performing urine sample culture and sensitivity testing, which over time leads to increased resistance.

On the relationship of morphology evolution and thermal conductivity of flax reinforced polypropylene laminates

This paper focuses on the morphology evolution in the forming process of unidirectional flax reinforced polypropylene composite laminates. The link between the morphology evolution and thermal conductivity during consolidation stages is investigated. Hot press forming allows to manufacture several composite laminates at different consolidation stages as a function of the compaction thickness. Microscopic evolution of the laminates in terms of morphology and porosity fractions are evaluated by scanning electron microscopy and X-ray microtomography (µ-CT). Hot disk technique is applied to measure the thermal conductivity of the laminates in in-plane and transverse directions. It is found that the in-plane thermal conductivity almost linearly increases with the reduction of porosity fraction. However, the transverse thermal conductivity remained constant. Beside the proposed relations, a theoretical model, based on a two-level Mori-Tanaka homogenization method is proposed. Considering the three-phases material (i.e., porosity, fiber, and polymer matrix), there is a good agreement between the experiment data and model predictions, but limited predictivity for porosity level above 15% certainly due to simplifying assumptions used in the predictive model.

ホットディスク法を用いた二層素材の相対的熱物性評価

The objective of this work is to compare the apparent thermal characteristics of ten different types of bi-layered materials using the hot disc technique. In this paper, bi-layered material refers to the components of a floor that consist of structural board and finishing materials; both are considered mainly wood-based materials. The result showed the influence of the thermal conductivity of the finishing material was dominant, but in some samples the presence of the air layer on the back side of the finishing material caused a decrease in thermal conductivity of the whole bi-layered material.

AKTIVITAS ANTIJAMUR EKSTRAK ETANOL PALA (Myristica fragrans HOUTT.) TERHADAP Malassezia furfur DAN Tricophyton mentagrophytes

Indonesia is a tropical country that has fair temperature and humidity supporting the growth of pathogenic fungi. Pathogenic fungi commonly encountered infecting humans in Indonesia are the species Malassezia furfur and Trichophyton mentagrophytes . Nutmeg ( Myristica fragrans Houtt.) is one of the Indonesian plants known to have potential antifungal activity. The purpose of this study was to examine the antifungal activity of the nutmeg ethanol extract against Malassezia furfur and Trichophyton mentagrophytes , determining the Minimum Inhibitory Concentration (MIC) and Minimum Killing Concentration (MKC) as well as testing the comparative value of nutmeg ethanol extract with ketoconazole. The research method used in testing the antifungal activity and the comparative value of the ethanol extract of nutmeg was the diffusion method for the paper disc technique and the microdilution method for testing the determination of MIC and MKC values. The results of this study show that the nutmeg ethanol extract had antifungal activity against Malassezia furfur and Trichophyton mentagrophytes .The MIC and MKC values of the nutmeg ethanol extract were the same for Malassezia furfur and Trichophyton mentagrophytes , namely the MIC value of the ethanol extract was 2,5%. Meanwhile, MKC value for ethanol extract was 5%, .The comparative values of ketoconazole antifungal activity with ethanol extract of the nutmeg against Malassezia furfur were 1:34, whereas against Trichophyton mentagrophytes were 1:12

Cu2+- and Zn2+-doped cobalt spinel ferrite: insights on structural, thermal conduction, electric, magnetic and elastic properties

M–Co{mathrm{Fe}}_{2}{mathrm{O}}_{4} (where M=Cu and Zn) nanoferrites were successfully prepared using the citrate auto-combustion technique. The main idea was drawn through a complete study of the structural, morphological, thermal, magnetic, and electrical properties. The obtain findings were explained in the light of incorporation both {mathrm{Cu}}^{2+} and {mathrm{Zn}}^{2+} ions in the Co{mathrm{Fe}}_{2}{mathrm{O}}_{4} crystal. All the investigated samples were found to belong to space group (Fd-3m) and space group number (227). The crystallite size of the Co{mathrm{Fe}}_{2}{mathrm{O}}_{4}, Cu–Co{mathrm{Fe}}_{2}{mathrm{O}}_{4}, and Zn–Co{mathrm{Fe}}_{2}{mathrm{O}}_{4} nanoparticles was found to be 8, 15, and 14, respectively. While, the lattice constants were 8.4 nm, 8.39 nm, and 8.42 nm, respectively. The doping exhibits enhancement of the elastic properties. Cu–Co{mathrm{Fe}}_{2}{mathrm{O}}_{4} shows young’ modulus at 278.97 GPa, while the shear modulus was 185.98 GPa, as highest obtained values compared to virgin and other doping samples. The highest saturation magnetization was observed for virgin sample, Co{mathrm{Fe}}_{2}{mathrm{O}}_{4}, (56.1 emu/g) compared to it being 46.9 and 45 emu/g for Cu–Co{mathrm{Fe}}_{2}{mathrm{O}}_{4} and Zn–Co{mathrm{Fe}}_{2}{mathrm{O}}_{4}, respectively. The highest magnetic susceptibility (0.639) was obtained for Zn–Co{mathrm{Fe}}_{2}{mathrm{O}}_{4}. The thermal conductivity, thermal diffusivity, and specific heat of the prepared samples were investigated by the hot disk technique at room temperature. The results have shown an enhancement in the thermal properties of Co{mathrm{Fe}}_{2}{mathrm{O}}_{4}-doped Zn and Cu rather than virgin Co{mathrm{Fe}}_{2}{mathrm{O}}_{4}, predicting required thermal stability in the working devices. The Cu–Co{mathrm{Fe}}_{2}{mathrm{O}}_{4} sample exhibits the highest value of thermal conductivity (0.95 W/m k), thermal diffusivity (0.75 m {mathrm{m}}^{2}/s), and specific heat (0.85 Mj/{mathrm{m}}^{3} k) compared to (0.6 and 0.82 W/m k), (0.52 and 0.6 m {mathrm{m}}^{2}/s), and (0.62 and 0.72 Mj/{mathrm{m}}^{3} k) for Co{mathrm{Fe}}_{2}{mathrm{O}}_{4} and Zn–Co{mathrm{Fe}}_{2}{mathrm{O}}_{4}, respectively. The electrical conductivity and permittivity of all ferrite samples were enhanced by augmenting the temperature. The highest values were achieved for Co{mathrm{Fe}}_{2}{mathrm{O}}_{4} sample. The present Co{mathrm{Fe}}_{2}{mathrm{O}}_{4}-doped {mathrm{Cu}}^{2+} and {mathrm{Zn}}^{2+} ions offer a decent contender material with appealing characteristics suitable for different electronic applications.

Methods of Removal of Hormones in Wastewater

Hormones are a type of emerging contaminant that reach the aquatic environment through wastewater effluents and which wastewater treatment plants (WWTP) cannot eliminate. The objective of this article was to determine the best hormone abatement technique between algae and microalgae, rotating biological discs, organic adsorbents, and activated carbon. For this, a critical review of the behavior of the abatement methods was conducted in the existing bibliographical scientific databases over the last eight years. Then, the Modified Saaty method was applied, establishing a relationship between removal efficiency, removal time, maintenance costs, stage of development, and environmental impact in each technique studied by a panel of experts, who weighted the chosen variables on a scale of 1–9 according to the variable’s importance. The results indicated that the best technique to abate hormones is one that uses organic adsorbents and which reached a final comparative value of 0.58/1, which indicates the suitability of the method to combine the five comparison variables. At the same time, the rotating biological disc technique reached a value of 0.17/1, indicating its deficiency in the balance between the analyzed variables.

Selection of a leaching system for the extraction of gold from the ore of the Byn’govskoye deposit

A theoretical substantiation of an environmentally friendly technology for extracting gold from mineral raw materials is presented. In terms of an alternative to conventional cyanide, the authors propose chlorine-bearing derivatives of organic isocyanuric acid (C3H3N3O3). In the studied process, this reagent combines the roles of a long-acting oxidant and complexing agent due to the resulting Cl– ion. For experimental purposes, the rotating disc technique was applied. Experimental results were evaluated by measuring the concentration of gold in solutions using the atomic adsorption method. The theoretical characteristics of gold dissolution using the proposed reagent were studied. In order to evaluate the applicability of the revealed regularities for practical purposes, comparative indicators for leaching gold from the ore of the Byn’govskoye deposit (Sverdlovsk Oblast) using the proposed reagent, cyanide and CYCAD cyanide substitute (China) were evaluated. The dependence of the gold disc dissolution rate on temperature, as well as leaching reagent and hydrochloric acid concentrations, were studied. In disc sample experiments, the exponential dependence of the dissolution rate on the concentration of the studied reagent was established. In this case, the maximum intensity of the process is achieved at a concentration higher than 50 g/dm3. The optimum acidity level comprises 0.3–0.4 g ion/dm3 of hydrochloric acid. Despite an increase in temperature being shown to accelerate the dissolution process, this appears to be technologically unjustified. Under optimal conditions, the gold disc dissolution rate reaches 0.5•10-3 g ion/(cm2•min), which is approximately one hundred times higher than during the dissolution by the cyanic solutions in conventional modes. Close gold extraction values were achieved in the solutions of cyanides and chlorine-bearing derivatives of isocyanuric acid during the leaching of gold from the ore under the comparable conditions. For CYCAD solutions, the same indicator is two times lower. The results of the performed studies demonstrate the high dissolution rate of gold using the proposed reagent along with the technological possibility of leaching gold from ores using this environmentally friendly reagent.