Zone Method Research Articles

Estimating transmissivity and storativity in a karst aquifer by direct and indirect methods

AbstractThe karst aquifer located in the Environmental Protection Area of Lagoa Santa, Minas Gerais, Brazil, exhibits the characteristic morphological features of an evolved karst environment, including large caves, sinkholes, and copious springs. Understanding the hydrogeological characteristics of karst aquifers is crucial for effective management of public resources and prevention of contamination, as these aquifers are highly vulnerable, making it essential to identify and mitigate potential risks. Given the ongoing economic and population growth in this region, the assessment of the hydrogeological parameters that control the dynamics of local flow becomes relevant for the proper evaluation of hydrogeological models and the management of water resources. Four classical pumping test analysis methods were compared to quantify the flow and storativity of the aquifer: Theis (1935), Neuman (1972), Moench (1984), and Agarwal (1980). In addition, indirect estimation methods based on the identification of capture zones and the analysis of recession curves of water courses were employed, since these approaches are cheaper and easier to apply in areas with low information. The statistical analysis of the results suggests that classical solutions can be applied to the karst aquifer to estimate hydrogeological parameters, apart from the Storage Coefficient obtained using the Neuman method. In general, the indirect estimation methods tend to produce values that are consistent with those obtained through direct methods, albeit with some reservations. The transmissivity values obtained from the pumping tests were approximately 3.0 × 10−4 m2/s, while the storage coefficient is estimated to be around 3.7 × 10−3. The indirect estimation methods yield transmissivity values of about 1.8 × 10−4 m2/s using the capture zone method, and storage coefficient values of 4.0 × 10−3 and 3.9 × 10−2 using recession curve analysis.

Calculation Method of Support Load Zoning and Mechanism of Mine Pressure Behavior in Upward Mining Face across Half of the Goaf along the Panel Direction

The 1515 mining face in Yongming Coal Mine was upward mined across half of the goaf along the panel direction. In this paper, the methods of field measurement, theoretical analysis, and numerical simulation were used to study the overlying rock fracture structure, support load characteristics, and the mechanism of mine pressure behavior across half of the goaf. The results indicate that the support load of the 1515 upward mining face across half of the goaf along the panel direction exhibits distinct zoning characteristics. The maximum support load is 1.37 times the minimum support load. The development height of the roof separation in the up-mining area is 1.74 times that in the entity coal area, at 9.1 m and 5.22 m respectively. The height of separation and hanging roof length increase and decrease, respectively, along the initial rock fracture area, tensile fracture area, structural fracture area, and compacted fracture area. Based on the definition of the variation coefficient “m” for immediate roof height and hanging roof coefficient “n”, a partitioned method for calculating support loads in the upward mining face across half of the goaf was proposed. Finally, the key parameter values for support loads in each zoning were provided and validated.

Photoluminescence and thermally stimulated luminescence properties of undoped and Tb-doped Sr3Gd(PO4)3 single crystals

Using the floating zone method, undoped and 0.5, 1, and 5% Tb-doped Sr3Gd(PO4)3 (SGPO) single crystals were synthesized. Investigations were conducted on the photoluminescence (PL) and thermally stimulated luminescence (TSL) of all the SGPO single crystals. The highest PL quantum yield was shown in the 5% Tb-doped single crystal among the synthesized SGPO single crystals. The undoped SGPO single crystal displayed an emission peak in both TSL and PL at 310 nm owing to the Gd3+ 4f–4f transition. In the Tb-doped SGPO single crystals, emission peaks in PL and TSL at 310–620 nm were caused by the 4f–4f transitions of Tb3+ in addition to Gd3+. In the TSL dose response function, the 1% Tb-doped SGPO single crystal exhibited the highest TSL intensity, and the TSL signal could be detected at least 0.01 mGy.

Mitigating Crack Propagation in Hybrid Composites: An Experimental and Computational Study

The exceptional properties of carbon nanotubes (CNTs) make them ideal nanofillers for various composite materials. In carbon fiber-reinforced polymer (CFRP) composites. CNTs can be grown on the carbon fiber surface to act as a third interface between the fiber and the matrix. However, it was established that the uncontrolled random growth of CNTs could exacerbate delamination in composite structures. Thick nanofiller films could hinder the epoxy from seeping into the carbon fiber, resulting in insufficient interlaminar strength. Hence, the density and distribution of nanofillers play a crucial role in determining the hybrid composite fracture mechanisms. In this investigation, CNTs were grown using the low-temperature technique into specific patterns over carbon fibers to discern their derived composites’ fracture properties. The composite fracture energy release was probed using a double cantilever beam (DCB) test setup and digital image correlation (DIC) to monitor interlaminar crack propagation. A standard finite element simulation model based on the cohesive zone method (CZM) was also utilized to delineate fracture behaviors of the various composite configurations. Results conclude that a coarser pattern of CNT growth enhances resistance to crack propagation, thus improving the interlaminar fracture toughness of a composite structure.

Optical and scintillation properties of Er-doped La3Ga5SiO14 single crystals emitting near-infrared photons

0.5, 1, 2, and 5% Er-doped La3Ga5SiO14 (LGS) single crystals were synthesized by the Floating Zone method and the photoluminescence (PL) and scintillation properties were characterized. Emission peaks appeared at visible–near-infrared (NIR) regions. Their spectral features matched with those due to the 4f–4f transitions of Er3+. The PL quantum yields of 0.5, 1, 2, and 5% Er-doped samples were respectively 45.0, 73.3, 82.5, and 69.4%. The decay times due to the 2H9/2–4I15/2 transitions of Er3+ were obtained when visible ranges were monitored under excitation of both visible lights and X-rays. All the prepared samples showed good linearity between the X-ray exposure dose rate and scintillation signals in NIR ranges. The best lower detection limit in prepared samples was 5 mGy/h recorded by the 2% Er-doped LGS.

Growth of β-Ga2O3 crystal with a diameter of 30 mm by laser-diode-heated floating zone (LDFZ) method

To investigate the effect of high-power laser heating on the floating zone (FZ) method, a crystal of β-Ga2O3 was grown by the LDFZ method using a newly developed optical system equipped with a 20-kW laser diode (LD) system as a heat source. The growth started from a twin-free seed crystal with a diameter of 7 mm and the diameter of the crystal was increased gradually up to 30 mm. With increasing the diameter of the crystal, three patterns of the beam intensity profile were switched to heat the whole of the molten zone locally and intensively. The intensity profile of the five beamlets irradiating the sample was adjusted with a combination of the zooming by the optical system and the partial blocking by the alumina cylinder. By the proper tuning of the beam profile and the proper selection of the diameter of the feed rod, the molten zone was kept stable against gravity. The obtained crystal has a layer texture without clear facets or cracks. It almost conserves the crystallographic direction of the seed crystal but is twinned except for a twin-free region near the seed crystal.

Preparation of Porous Ga‐Doped TiO2 Composite Aerogel and Its Bactericidal Activity against Escherichia coli and Staphylococcus aureus

In this work, a novel strategy for preparing Ga‐doped TiO2 composite aerogel antibacterial agent through the sol–gel method and supercritical technology is demonstrated. The specific surface area of the samples is as high as 175 m2 g−1 and exhibits a 3D network structure with a multistage pore distribution. The obtained antibacterial agent combines the phototoxicity of TiO2, photo‐independent toxicity of Ga3+, and structural properties of aerogels, showing a synergistic antibacterial effect. On the one hand, TiO2 produces reactive oxygen species in the presence of light, thus destroying the structure of bacteria. On the other hand, Ga3+ competitively replaces Fe3+ and hinders the metabolic process of bacteria. Moreover, the structural properties of aerogels promote superior antimicrobial performance of antibacterial agents. Their antibacterial properties against Escherichia coli and Staphylococcus aureus bacteria are mainly investigated through the inhibition zone and natural colony counting method. In the results, it is shown that the structure and bactericidal activity of TiO2 aerogel is effectively optimized with Ga3+ doping. The maximum zone of inhibition of the composite aerogel against E. coli and S. aureus is 17.5 and 16 mm, and the bactericidal rate is as high as 98.57% and 96.60%, which exhibit outstanding bactericidal performance.

Floating Zone Growth of Pure and Pb-Doped Bi-2201 Crystals

In this review, we summarize recent progress in crystal growth and understanding of the influence of crystal structure on superconductivity in pure and Pb-doped Bi2Sr2CuOy (Bi-2201) materials belonging to the overdoped region of high-temperature cuprate superconductors. The crystal growth of Bi-2201 superconductors faces challenges due to intricate materials chemistry and the lack of knowledge of corresponding phase diagrams. Historically, a crucible-free floating zone method emerged as the most promising growth approach for these materials, resulting in high-quality single crystals. This review outlines the described methods in the literature and the authors’ synthesis endeavors encompassing Pb-doped Bi-2201 crystals, provides a detailed structural characterization of as-grown and post-growth annealed samples, and highlights optimal growth conditions that yield large-size, single-phase, and compositionally homogeneous Bi-2201 single crystals.

Solvable non-Hermitian skin effects and real-space exceptional points: non-Hermitian generalized Bloch theorem

Non-Hermitian systems can exhibit extraordinary boundary behaviors, known as the non-Hermitian skin effects, where all the eigenstates are localized exponentially at one side of lattice model. To give a full understanding and control of non-Hermitian skin effects, we have developed the non-Hermitian generalized Bloch theorem to provide the analytical expression for all solvable eigenvalues and eigenstates, in which translation symmetry is broken due to the open boundary condition. By introducing the Vieta’s theorem for any polynomial equation with arbitrary degree, our approach is widely applicable for one-dimensional non-Hermitian tight-binding models. With the non-Hermitian generalized Bloch theorem, we can analyze the condition of existence or non-existence of the non-Hermitian skin effects at a mathematically rigorous level. Additionally, the non-Hermitian generalized Bloch theorem allows us to explore the real-space exceptional points. We also establish the connection between our approach and the generalized Brillouin zone method. To illustrate our main results, we examine two concrete examples including the Su–Schrieffer–Heeger chain model with long-range couplings, and the ladder model with non-reciprocal interaction. Our non-Hermitian generalized Bloch theorem provides an efficient way to analytically study various non-Hermitian phenomena in more general cases.

Experimental Construction and Validation of Revised Drucker–Prager Model Using Finite Element Method for Moisture Condensation Zone in Bentonite-Bonded Silica Sand

For predicting casting deformation by FEM (finite element method) thermal stress analysis, this paper experimentally constructed and validated the Drucker–Prager (DP) model and its revised model (RDP) for the condensation zone of bentonite-bonded sand molds. The condensation zone has been known as a remarkably low-strength region in the mold, and its mechanical response should be dominant to the casting deformation. To construct the models through uniaxial and triaxial compression tests, the test pieces reproducing the condensation zone were prepared by permeating water vapor through a test piece of bentonite-bonded sand. The constructed models were then applied to the FEM stress analysis of the triaxial test to validate them by comparing the analytical stress–strain curves with the experiment. The experimental stress–strain curve after permeating water did not show any distinct yielding point; however, the analytical curve with the original DP model clearly exhibited a yielding point due to the yield criterion of the model. The distinct yielding criterion should be essentially fatal to reproduce the stress–strain relationship of the condensation zone. Contrarily, the RDP model reproduced the experimental curve with less than 10 % error and was found to be advantageous for modeling the smooth stress–strain relationship of the condensation zone.

Performance of lathyrus varieties under different establishment methods in Red and Laterite Zone of West Bengal

A field experiment was conducted in split-plot design to study the performance of lathyrus varieties (Nirmal, Prateek and Ratan) under three different establishment methods (broadcasting, line-sowing and dibbling) at Regional Research Sub-Station, Bidhan Chandra Krishi Viswavidyalaya, Raghunathpur West Bengal during rabi season of 2020-21. Irrespective of varieties, lathyrus sown on line sowing and dibbling methods required 2.0 and 3.2 more days to complete life cycle over broadcast sowing. Though, broadcast sowing of lathyrus led to highest number of plants/m (34.2) at maturity stage compared to line sowing (26.8 plants/m) and dibbling (23.2 plants/m) method, but crop sown in line yielded highest (1401 kg/ha) with highest net return (INR. 21,745/ ha). Among three varieties, Ratan appeared suitable due to greater seed yield (1337 kg/ha), net return (INR. 19,723/ha) and B: C ratio (1.57) than Nirmal and Prateek in red and laterite zone of West Bengal.

Antimicrobial Activity against Antibiotic-resistant Pathogens and Antioxidant Activity and LCMS/MS Phytochemical Content Analysis of Selected Medicinal Plants

Medicinal plants are a major source of numerous therapeutic agents, and the emergence of pathogenic bacteria has rekindled interest in traditional medicine systems as an alternative approach to overcoming resistance. The dried plant material of four medicinal plants, namely Terminalia arjuna (bark), Terminalia bellirica (fruit), Aegle marmelos (leaves), and Bacopa monnieri (leaves), was powdered, and aqueous extracts were prepared. The antimicrobial activity of the extracts was evaluated against three clinically important strains: Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli 385. As E. coli 385 was resistant to the broadest spectrum of antibiotics tested, it was classified as (MDR multi-drug resistant). E. coli, Bacillus subtilis, Mycobacterium smegmatis (MTTC), and Vibrio alginolyticus (ATCC) were also assessed using the agar well diffusion method for zones of inhibition and minimum inhibitory/bactericidal concentration (MIC/MBC). Clinically important strains were found to be sensitive to the aqueous extract of T. bellerica (19.51 ± 0.61 mm) with MICs ranging from 0.31 to 0.62 mg/ml. The MDR strain was also sensitive to Bellirica monnieri (16.10 ± 0.31 mm) aqueous extract. To determine the potential for a wide range of applications, the antioxidant activities of the extracts were evaluated using DPPH, ABTS, and FRAP assays. The T. arjuna plant extract exhibited the highest radical scavenging activity with the lowest EC50 values for DPPH (1.15 ± 0.061 mg/ml) and ABTS (1.02 ± 0.07 mg/ml). The plant extracts were characterized by UV-visible spectroscopy, Fourier-transform infrared spectroscopy, and LC-MS/MS.

Extended finite element-based cohesive zone method for modeling simultaneous hydraulic fracture height growth in layered reservoirs

In this study, a fully coupled hydromechanical model within the extended finite element method (XFEM)-based cohesive zone method (CZM) is employed to investigate the simultaneous height growth behavior of multi-cluster hydraulic fractures in layered porous reservoirs with modulus contrast. The coupled hydromechanical model is first verified against an analytical solution and a laboratory experiment. Then, the fracture geometry (e.g. height, aperture, and area) and fluid pressure evolutions of multiple hydraulic fractures placed in a porous reservoir interbedded with alternating stiff and soft layers are investigated using the model. The stress and pore pressure distributions within the layered reservoir during fluid injection are also presented. The simulation results reveal that stress umbrellas are easily to form among multiple hydraulic fractures’ tips when propagating in soft layers, which impedes the simultaneous height growth. It is also observed that the impediment effect of soft layer is much more significant in the fractures suppressed by the preferential growth of adjoining fractures. After that, the combined effect of in situ stress ratio and fracturing spacing on the multi-fracture height growth is presented, and the results elucidate the influence of in situ stress ratio on the height growth behavior depending on the fracture spacing. Finally, it is found that the inclusion of soft layers changes the aperture distribution of outmost and interior hydraulic fractures. The results obtained from this study may provide some insights on the understanding of hydraulic fracture height containment observed in filed.

Investigation on crack propagation of SiCf/SiC composite via PF-CZM method

SiCf/SiC composite materials had become a research hotspot in the fields of aerospace materials and nuclear materials in recent years. This materials have high strength, radiation resistance, high temperature resistance and oxidation resistance. However, SiC is a typical brittle material prone to being damaged due to stress concentration in some cases, leading to cracks and even component failure. Therefore, this study employed an accurate and efficient numerical simulation method, phase field cohesive zone method (PFCZM), to investigate the microscopic damage behavior of SiCf/SiC composite materials. This study aimed to illustrate the influence of the thickness of pyrolytic carbon (PyC) interface layer on the failure behavior of SiCf/SiC composite materials. Firstly, this study conducted relevant verification of PFCZM. Secondly, numerical simulations of crack initiation, crack propagation, and final damage were performed by establishing a representative volume element (RVE). Observing the simulation results, it was noted that at low strain, when PyC was thicker, the SiCf/SiC composite materials exhibited slight damage to both the SiC matrix and PyC interface. Conversely, when PyC was thinner, the SiCf/SiC composite materials displayed only slight damage to PyC interface. As the PyC thickness increases, the damage to PyC interface decreases, while the damage to SiC becomes more prominent. Simultaneously, a competitive relationship in the damage behavior of SiCf/SiC composite materials can be found after the SiC matrix has cracked: When PyC is thinner, the damage primarily manifests as interlayer delamination between the SiC matrix and the SiC fiber. Conversely, when PyC is thicker, it manifests in PyC failure. Finally, this study concluded that, in this investigation, a PyC interface layer with a thickness of 0.1 μm exhibited the most effective protective effect on SiCf/SiC composite material.

Advances in high-pressure laser floating zone growth: The Laser Optical Kristallmacher II (LOKII).

The optical floating zone crystal growth technique is a well-established method for obtaining large, high-purity single crystals. While the floating zone method has been constantly evolving for over six decades, the development of high-pressure (up to 1000bar) growth systems has only recently been realized via the combination of laser-based heating sources with an all-metal chamber. While our inaugural high-pressure laser floating zone furnace design demonstrated the successful growth of new volatile and metastable phases, the furnace design faces several limitations with imaging quality, heating profile control, and chamber cooling power. Here, we present a second-generation design of the high-pressure laser floating zone furnace, "Laser Optical Kristallmacher II" (LOKII), and demonstrate that this redesign facilitates new advances in crystal growth by highlighting several exemplar materials: α-Fe2O3, β-Ga2O3, and La2CuO4+δ. Notably, for La2CuO4+δ, we demonstrate the feasibility and long-term stability of traveling solvent floating zone growth under a record pressure of 700bar.

Application of MicroResp™ for quick and easy detection of plastic degradation by marine bacterial isolates

Microplastic debris in the marine environment is a global problem. Biodegradable polymers are being developed as alternatives to petroleum-based plastics, and quick and easy methods for screening for bacterial strains that can degrade such polymers are needed. As a screening method, the clear zone method has been widely used but has technical difficulties such as plate preparation and interpretation of results. In this study, we adapted the MicroResp™ system to easily detect biodegradation activity of marine bacteria in a 3-day assay. Among the 6 bacterial strains tested, 3, 2 and 1 strain degraded poly (butylene succinate-co-adipate) (PBSA), poly (ε-caprolactone) (PCL) and poly (3-hydroxybutyrate-co-3-hydroxyhexanoate), respectively. Only one strain that showed degradation activity of PBSA and PCL in the MicroResp™ system was also positive in the clear zone assay on the respective emulsion plates. Our results show that the adapted MicroResp™ system can screen for bacterial strains that degrade plastic.

Combination Of HCD, Persona, MVP, and Thumb Zone for Designing TNI Physical Fitness Monitoring Application

This research contributed to producing a combination of design methods and design of the Indonesian National Army (TNI) physical fitness monitoring application. This research is very important because TNI institutions really need a physical fitness monitoring application to be able to make the right decisions. The design of the physical fitness monitoring application primarily uses the Human-Centered Design (HCD) method which is then combined with the Persona, Minimum Viable Product (MVP) and The Thumb Zone methods. The combination of HCD with Persona has been proven to be used to understand and determine usage content and user needs. The combination of HCD with MVP has proven to be able to be used to produce design solutions to meet user needs. The combination of HCD with Thumb Zone has proven to be able to be used to evaluate designs against user needs. Finally, as many as 20 Persona respondents agreed that the combination of HCD, Persona, MVP, and Thumb Zone proved reliable for producing physical fitness monitoring application design solutions that can be used naturally and meet the needs of TNI.

Characterization of scintillation properties in Ca(Nb,Ta)2O6 single crystals

CaNb2-xTaxO6 (x = 0, 0.2, 0.5 and 1) single crystals were fabricated by the floating zone method, and their photoluminescence (PL) and scintillation properties were evaluated. Under excitation at 280 nm, CaNb2-xTaxO6 single crystal showed a broad emission band at 400–600 nm. From the decay time constant, the observed emission was attributed to the charge transfer (CT) from the Nb5+ to the O2−. Under X-ray irradiation, an emission peak was observed at 470 nm, and the scintillation decay time profile suggested that the origin of the emission was also CT from the Nb5+ to the O2−. CaNb2O6 showed the highest light yield of 15,000 ph/MeV and the lowest afterglow level of 6.03 ppm among the synthesized samples.

Marine Ascomycetes Extract Antifungal Susceptibility against Candida spp. Isolates from Oral Candidiasis HIV/AIDS Patient: An In Vitro Study.

The etiology of oral candidiasis (OC) was Candida albicans, C. krusei, C. dubliniensis, C. tropicalis that are frequently found in human immunodeficiency virus/ acquired immunodeficiency syndrome (HIV/AIDS) patients. Marine ascomycetes (MA) have been widely reported as an important producer of various antibiotic compounds. However, there is limited study of antifungal compounds from MA against Candida species. The aim of this study was to investigate the antifungal susceptibility of MA against Candida spp. isolates from OC HIV/AIDS patient. Trichoderma sp. is a sponge-associated fungus collected from Karimunjawa National Park, Central Java, Indonesia. The validation of C. albicans, C. krusei, C. dubliniensis, C. tropicalis. was done by ChromAgar. This study was true experimental with post-test only control group design; the sample was four replications for each group. Nystatin administration (K +), the golden standard antifungal drug, was used. The minimum fungicidal concentration (MFC), minimum inhibitory concentration (MIC), and diffusion zone methods were done. Analysis of variance difference test, and post-hoc Tukey's honest significant different were done to analyze the significant different between groups (p ≤ 0.05). The MFC and MIC of MA against C. albicans, C. krusei, C. dubliniensis, and C. tropicalis were found at 12.5%. In addition, the greatest diffusion zone of MA against C. albicans, C. krusei, C. dubliniensis, and C. tropicalis was found at 12.5%. There is no appreciable difference in antifungal activity between K + and 12.5% of MA extract (p ≥ 0.05). Concentration of 12.5% MA extract has antifungal susceptibility against Candida spp. isolates from OC HIV/AIDS patient.

Investigation of the permeability build-up method in the bottom-hole zone of the pay zone

In oil wells, the bottomhole formation zone is subjected to various influences during drilling, development and operation. The porous medium of the bottomhole zone is clogged by heavy components of the produced products and rock particles, reducing permeability and production. Various technologies are used to restore bottomhole permeability. A new method has been developed, including injection of a composition containing aqueous sodium bicarbonate solution with the addition of a chemical reagent, light oil and an acid solution into the formation. The essence of the acid treatment new method of heterogeneous terrigenous formations is that high permeable zones are blocked by a foam system, and injection of acid solution activates low-permeable zones. The new method developed in laboratory conditions was tested in field conditions. The test results showed that the set objectives were achieved.