Hexamethylenetetramine Research Articles

Prior antibiotics exposure is associated with an elevated risk of surgical site infections, including anastomotic leakage, after colon cancer but not rectal cancer surgery: A register-based study of 38,839 patients.

Gut microbiota composition has been implicated in surgical site complications after colorectal cancer surgery. Antibiotics affect gut microbiota, but evidence for a role in surgical site complications is inconclusive. We aimed to investigate use of prescription antibiotics during the years before surgery in relation to the risk of surgical site infections, including anastomotic leakage, within 30 days after surgery. Cardiovascular/neurological complications and the urinary antiseptic methenamine hippurate, for which there is no clear link with the microbiota, were used as negative controls. We conducted a patient cohort study using complete population data from Swedish national registers between 2005 and 2020. The final study population comprised 26,527 colon cancer and 12,312 rectal cancer cases with a 4.5 year exposure window. In colon cancer patients, antibiotics use was associated with a higher risk of surgical site infections (adjusted odds ratio (aOR) for any versus no use = 1.20, 95% confidence interval (CI) 1.10-1.33) and anastomotic leakage in particular (aOR =1.19, 95% CI 1.03-1.36), both with dose-response relationships for increasing cumulative antibiotics use (Ptrend = <0.001 and Ptrend = 0.047, respectively). Conversely, associations in rectal cancer patients, as well as for the negative controls cardiovascular/neurological complications and methenamine hippurate, were null. In conclusion, prescription antibiotics use up to 4.5 years before colorectal cancer surgery is associated with a higher risk of surgical site infections, including anastomotic leakage, after colon cancer but not rectal cancer surgery. These findings support a role for antibiotics-induced intestinal dysbiosis in surgical site infections.

Facet dependent ultralow thermal conductivity of zinc oxide coated silver fabric for thermoelectric devices

The conversion efficiency of a thermoelectric power generator depends on the dimensionless figure-of-merit (ZT) of the constituent thermoelectric materials, which is mainly determined by their Seebeck coefficient as well as the electrical and thermal conductivity. ZnO holds promise for thermoelectric applications, yet its use is currently limited by low electrical conductivity and high thermal conductivity. Herein, we demonstrate how thermal conductivity of ZnO can be significantly reduced by intelligently combining it with a cellulose-based Ag fabric using a one-step hydrothermal method, and how different ratios of zinc nitrate hexahydrate (ZNH) to hexamethylenetetramine (HMT) can be used to fine-tune the thermoelectric performance of the resulting composite. We show that as-prepared samples have a composite structure of Ag, Zn and O without any other impurity phases. We propose that the facet dependent crystal growth orientation, from the c-axis in (101) planes to the a-axis in (100) plane, amplify phonon scattering within the material, impeding effective heat transfer and thereby lowering overall thermal conductivity to 0.046 W/mK at room temperature for composites with a 1:1 ZNH to HMT ratio.

Coordination Tuning of FeNi-HMT Frameworks Derived Effective Hybrid Catalysts for Water Oxidation.

FeNi-based hybrid materials are promising oxygen evolution reaction (OER) catalysts for water electrolysis in hydrogen generation. In this work, the coordination tuning of FeNi-HMT frameworks was achieved by simply changing the Fe/Ni ratios using hexamethylenetetramine (HMT) as an organic ligand, and the derived hybrid FeNi catalysts with varied compositions were probed for OER. Incorporating varying amounts of Fe3+ by adjusting the Ni/Fe ratio results in different metal-organic framework (MOF) structures, and higher Fe feed leads to the formation of amorphous structures due to the coordination structure destruction from the weaker coordination capacity of Fe3+ compared to Ni2+ combining with the tertiary amine ligand. Among them, the FeNi-HMT (with the Fe/Ni molar ratio of 1/1) derived catalyst, consisting of Fe0.36Ni0.64 alloy/Ni0.4Fe2.6O4 spinel oxide heterostructures supported by graphitized carbon matrix, exhibits the highest OER performance. The unique structure facilitates significant electron transfer at the alloy/spinel interface due to the large work function difference between each phase. This strong electronic effect downshifts the d-band center of the catalyst and optimizes the binding energies to the crucial oxygenated intermediates, thereby promoting the OER kinetics. This work highlights the importance of the coordination tuning of FeNi-HMT frameworks for highly efficient catalyst development.

Preparation of unique corn-stalk-like MnO₂/CoNi nanowires via in situ epitaxial attachment growth for monitoring environmental pollutant hydrazine

This paper presents the synthesis of a novel corn-stalk-like MnO₂/CoNi oxide composite using an in situ epitaxial attachment growth strategy, in which CoNi oxide nanosheets are anchored onto MnO₂ nanowires. The one-dimensional MnO₂ nanowires, with their large specific surface area, serve as a support to enhance the electronic conductivity of the CoNi oxides. Hexamethylenetetramine (HMTA) is employed as an alkaline linking agent, playing a key role in shaping the CoNi oxide nanosheets and ensuring their successful growth on the MnO₂ nanowires. The MnO₂/CoNi oxide composite-based electrochemical sensor exhibits excellent synergistic and interfacial effects, promoting electron transfer and charge migration. This composite material shows outstanding electrocatalytic performance for hydrazine detection, with a broad linear range (0.48−6106.58 μM), low detection limit (0.286 μM, S/N = 3), and high sensitivity (0.037 μA μM⁻1). Moreover, when tested for hydrazine detection in water samples, the sensor achieved a recovery rate of 95.7–105 %, highlighting its high sensitivity and rapid response in practical applications.

Catalytic hydrolysis of HCN on the coupled sites of Lewis acid and surface hydroxyl of Fe-BEA catalyst leading to the presence of HCHO positively affects NH3-SCR activity

Formaldehyde (HCHO) in the exhaust gas of diesel or natural gas engines is usually considered to be a serious hindrance to the NH3-SCR process. However, the promotion effects of HCHO on the NH3-SCR activity and its temperature dependence were discovered in this work for the first time. For the Fe-BEA catalysts, below 300 °C, a notable decrease in activity observed, up to 40 % at 300 °C, and HCN selectivity reached 35 %. However, with the increase in temperature, a significant promotion effect was produced. Not only for the increase of NOx conversion, but also the diminish of the by-product HCN. The disparity in the number and activity of Lewis acid sites (Fe3+) and surface hydroxyls was the primary reason why Fe-BEA catalysts with varying Fe contents exhibited different influence. The presence of HCHO resulted in a modification of the oxidation pathway of NH3 at high temperatures. Surface hydroxyls facilitated the hydrolysis reaction of the as-formed HCN to produce NH3, with NH3 on Lewis acid sites subsequently re-participating in the SCR process. This enhanced the NOx conversion and the selectivity of carbon-containing products. Furthermore, it was demonstrated that HCHO completely converted to hexamethylenetetramine (HMTA) by reacting with NH3 prior to passing through the SCR catalyst. The thermal decomposition of HMTA on the catalyst was identified as a crucial step for the subsequent generation of HCN, and the detailed mechanism of how to effectively inhibit the decrease of de-NOx activity and the formation of HCN in the HCHO-containing NH3-SCR conditions was elucidated. This study paves the way for the development of effective SCR catalysts for the synergistic control of HCN from mobile and stationary sources.

Effect of Hexamethylenetetramine concentration on the structural, morphological, optical and bactericidal action of Eu-doped TiO2 quantum dots derived through wet chemical method

Recently, it has been established that bacteria are quickly developing resistance to traditional antibiotics; as a result, one of the most significant challenges facing the healthcare sector is treating illnesses linked to bacterial infections. In this work, we used a simple wet chemical approach to easily prepare pure TiO2 and Eu-doped TiO2 quantum dots (QDs) with different hexamethylenetetramine (HMT) concentrations: 0.1, 0.15, and 0.2 M. As indicated by XRD results, the pure TiO2 possesses the tetragonal anatase phase, while the Eu-doped TiO2 samples prepared with the support of HMT content during sample synthesis promotes the amorphous phase. The Eu-doped TiO2 sample prepared at 0.1 M HMT has an almost uniform distribution of ultra-fine QDs, with an average particle size distribution of 2.05 ± 0.17 nm, according to the TEM image. The Eu 3d core level doublet at 1134.29 and 1164.21 eV, which correspond to Eu3+3d5/2 and Eu3+3d3/2, respectively, is displayed in the XPS data for the sample prepared at 0.1 M HMT. Based on the findings of the Tauc plot, the sample prepared at 0.2 M HMT is found to have a larger optical band gap than the pure TiO2 and Eu-doped TiO2 samples prepared at different HMTA concentrations. According to antibacterial tests, the zone of inhibition for E. coli increases from 7 ± 0.55 to 12 ± 0.60 when the concentration of the Eu-doped TiO2 sample prepared at 0.15 M HMT is increased from 100 to 300 µg/mL. In the field of biomedical application, this enhanced antibacterial activity of Eu-doped TiO2 QDs can be utilized to create a potent medication for bacterial resistance.

Highly-efficient separation of pyromellitic acid and trimellitic acid mixtures via forming deep eutectic solvents: Experiment and calculation

Pyromellitic acid (PMA) and trimellitic acid (TMA) are significant chemical raw materials and intermediates. They simultaneously exist in the industry processes of synthesis and are difficult to be separated. In this work, several kinds of biodegradable compounds were chosen as hydrogen bond acceptors (HBAs) to separate PMA and TMA mixtures from acetone solutions via forming deep eutectic solvent (DES). It has been found that all these compounds can separate PMA and TMA mixtures to obtain pure PMA or TMA. However, the interaction between HBAs and PMA or TMA is quite different. Choline chloride cannot extract TMA but can form a DES with PMA in acetone. Hexamethylenetetramine (HA) and l-carnitine (L-car) can form DESs with both PMA and TMA in acetone solution. But when L-car or HA is added, the extraction rate of PMA is larger than that of TMA until the extraction rate of PMA reach 100%, and pure TMA is left in the acetone solution. The selective separation mechanism was explored by infrared spectroscopy combined with quantum chemistry calculation, and the strength and site of the interaction between extractants with PMA and TMA were calculated.

Adherence to Non-Antibiotic Prophylactic Regimens in Women with Recurrent Urinary Tract Infections.

Non-antibiotic regimens such as methenamine hippurate, D-mannose, and vaginal estrogen are often prescribed as prevention for recurrent urinary tract infections (rUTIs). The objective of our study was to describe adherence rates in women prescribed non-antibiotic prophylaxis for rUTI and to explore factors associated with adherence. This was an ambispective cohort study describing and comparing adherence to non-antibiotic prophylactic regimens for rUTIs. Adult women who sought care from a Urogynecology clinic at a tertiary care center for rUTIs or frequent UTIs between January 2020 and December 2021 were included if they were prescribed a non-antibiotic prophylactic regimen. The Medication Adherence Questionnaire (MAQ) was administered to all eligible patients prospectively and then their charts were reviewed retrospectively for demographic and clinical factors. A score of 0 on the MAQ defined medication adherence. Any score ≥ 1 defined medication non-adherence. A total of 90 patients met the inclusion criteria and completed the MAQ, with 33 (37%) in the adherent group and 57 (63%) in the non-adherent group. Mean age was 64.7 (± 14.7) years. Vaginal estrogen (81.1%) was the most commonly prescribed prophylactic regimen, followed by methenamine hippurate (26.7%). 73.3% of patients met criteria for rUTI at the index visit as per the American Urogynecologic Society best-practice statement. No demographic or clinical factors were associated with adherence to non-antibiotic prophylactic regimens. Non-antibiotic prophylactic rUTI regimens are commonly prescribed; however, adherence remains low at 37%. There were no predictors associated with patient compliance. Clinicians should therefore inquire about adherence prior to escalating treatment.

Highly crosslinked resin prepares hard carbon anode for enhanced sodium storage performance and reduced cost

Resins have shown significant potential as a precursor for hard carbons (HCs) in sodium-ion batteries (SIBs) due to their high purity and adjustability. However, the high cost and low Na+ storage capacity limit their industrialization. Herein, the highly crosslinked resin is developed by linear phenolic resin crosslinking with inexpensive hexamethylenetetramine (HMTA) via the C-N and methylene bridges between phenolic rings, which can effectively reduce the resin consumption ratio by over 44% per unit mass and regulate the sodium storage performance of the prepared HC with a high reversible capacity of 323.9 mAh g-1 and an initial coulombic efficiency (ICE) of 90.7% at 15 mA g−1, where a high plateau capacity of 286.8 mAh g-1 is proved to be a coupled storage mechanism of intercalation and pore-filling behavior. Meanwhile, defects associated with hydrogen content, rather than nitrogen defects, are verified to be directly linked to slope capacity. Furthermore, the 18650 cylindrical-type batteries assembled with this HC anode coupled with NaFe1/3Ni1/3Mn1/3O2 cathode achieve a high energy density of about 280.9 Wh kg−1 and excellent capacity retention of 86.4% over 2500 cycles, providing a promising prospect for the practical application of the resin-based HC for SIBs.

Effects of crosslinker concentration on curing process and performances of needled fiber preform reinforced phenolic aerogel composite using process simulation and comprehensive experiments

A kind of needled quartz/carbon fiber preform reinforced phenolic aerogel composite (NQCF/PR) was fabricated through impregnating needled fiber preform with phenolic resin precursor solution, followed by sol–gel polymerization and solvent drying. The needled fiber preform serves as lightweight quasi-three-dimensional reinforcement, while phenolic aerogel matrix provides high porosity and low thermal conductivity. During fabrication of aerogel composite part using vacuum-assisted resin infusion process, distribution of crosslinker hexamethylenetetramine (HMTA) in precursor solution can be problematic, as precipitated crosslinker particles may be filtered by fibrous preform. In this study, the impact of HMTA filtration induced heterogeneous structure on subsequent curing process was investigated using process simulation. Temperature effects of sol–gel polymerization and solvent evaporation were considered through establishment of corresponding kinetic models. Impacts of heterogenous structure on distribution of temperature, resin curing degree and solvent conversion degree in large hemispherical aerogel composite structure were investigated. This leads to variations in gel network and pore structure of aerogel, thereby affecting final material performance. Based on experimental results, as HMTA concentration increases, compressive performance of NQCF/PR obviously increases. Among these, NQCF/PR with 4.7 wt% HMTA provides a balance of lightweight nature (0.25 g/cm3), excellent thermal insulation property (0.052 W·m−1·K−1) and compressive performance (strength of 0.35 MPa).

Unexpected mineral impact on organic evolution during simulated aqueous alteration in asteroids

The presence of organic matter in carbonaceous chondrites provides valuable information about the early composition of the Solar System. Although they are considered primitive, the majority of these chondrites have undergone secondary processes subsequent to their formation. These processes, such as aqueous alteration, have altered their composition. The effect of aqueous alteration on minerals is well known, but the effect on organic matter and/or on an organo-mineral system have been little studied. Here, we report experimental results devoted to investigate the chemical evolution of a hypothetical initial chondritic material subjected to hydrothermal alteration under reducing conditions at low-temperature. The mixtures consist of different anhydrous minerals (peridot, feldspar, troilite) together with hexamethylenetetramine (HMT) chosen as a model molecule inherited from the interstellar grains. After different times at 80 °C, the large molecular diversity formed is highly influenced by the presence and the nature of the minerals, as highlighted in particular by the evolution of the amide produced. The presence of minerals in the mixture appears to influence the reactivity of the system more through the formation of salts and chelates than through surface adsorption mechanisms. The most pronounced effect is observed in the presence of troilite, both in the degradation of HMT and in the abundance of amides formed. The study of the mutual influence of minerals and organic matter, and their intrinsic transformations in the media during the processes, could help to understand about the origin of organic molecules observed in carbonaceous chondrites.

Boosting the electrocatalytic overall water splitting performance by synergistically coupling N-doped delaminated niobium carbide MXene and N-doped graphitic carbon

A robust trifunctional electrocatalyst based on N-doped delaminated niobium carbide (N-Nb4C3Tx) nanosheets encapsulated by N-doped graphitic carbon (NGC) (abbreviated as N-Nb4C3Tx/NGC) is synthesized, which exhibits a low overpotentials of 96 and 291 mV at 10 mA cm−2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. The superior electrocatalytic performance can be attributed to the synergetic effect of the highly conductive N-Nb4C3Tx and doping of the high-content NGC. The introduction of N species plays an important roles of generating graphitic N-doped carbon species and anchoring N in the carbon matrix, which further boost the electrocatalytic activity. The structure properties and nitrogen content of MXene were regulated by the mass ratio of Nb4C3Tx to hexamethylenetetramine (HMTA). These results indicate that the method of synergistically coupling N-Nb4C3Tx and NGC can boost the HER, OER, and overall water splitting performance, providing a new strategy for the development of economical and efficient MXene based electrocatalysts.

Determination of ammonia nitrogen by surface-enhanced Raman spectroscopy and DFT studies

Ammonia nitrogen is one of the most important indicators for evaluating the quality of water bodies. It is very difficult to determine ammonia nitrogen directly by Surface-enhanced Raman spectroscopy (SERS) in practice. In order to realize SERS determination of ammonia nitrogen, in this paper, SERS combined with density functional theory (DFT) was used to investigate why ammonia nitrogen needs to be derivatized to hexamethylenetetramine (HMTA) and why HMTA can be determined using SERS. The molecular electrostatic potential (MEP) results exhibit that there was no adsorption site on the surface of ammonia nitrogen, whereas its derivate HMTA had four available adsorption sites. This provides a basic guarantee for the SERS detection of HMTA. The molecular adsorption state of HMTA on the gold nanoparticles surface was concluded from the binding energies, the bond length, and the Raman activity spectra. Among them, the HMTA-Au4 complex has the lowest bond energy (−586.873 Kcal/mol) and the shortest bond length (2.161 Å), which is the most stable state and its Raman activity spectrum is the closest to the experimental data. Calculations results of frontier molecular orbital (FMO) demonstrate that the energy gap of HMTA and HMTA-Au4 complex are 0.30258 eV and 0.10947 eV, respectively, with a really obvious difference between them, which indicates that the HMAT-Au4 complex possessed higher chemical reactivity. In addition, charge transfer phenomenon on the MEP of HMTA-Au4 complex was deduced due to the change in the symmetry of its charge distribution, which can be explained the mechanism of chemical enhancement in the detection of HMTA by SERS. The selective enhancement at 1048 cm−1 peaks in theoretical spectrum and at 1044 peaks cm−1 in experimental spectrum provided theoretical and practical basis for indirect determination of ammonia nitrogen by SERS. The obtained results will help to better understand the reasons why some components are difficult to be directly determined by SERS, and why these components need to be derivatized. It provides a new method for components that are difficult to detect by SERS.

Electrocatalytic Coupling of Nitrate and Formaldehyde for Hexamethylenetetramine Synthesis via C-N Bond Construction and Ring Formation.

Hexamethylenetetramine (HMTA) is extensively used in the defense industry, medicines, food, plastics, rubber, and other applications. Traditional organic synthesis of HMTA relies on ammonia derived from the Haber process at high temperatures and pressures. In contrast, electrochemical methods enable a safe and green one-pot synthesis of HMTA from waste NO3-. However, HMTA synthesis through the electrochemical method is challenging owing to the complex reaction pathways involving C-N bond construction and ring formation. In this study, HMTA was efficiently synthesized over electrochemical oxidation-derived copper (e-OD-Cu), with a yield of 76.8% and a Faradaic efficiency of 74.9% at -0.30 VRHE. The catalytic mechanism and reaction pathway of HMTA synthesis on e-OD-Cu were investigated through a series of in situ characterization methods and density-functional theory calculations. The results demonstrated that the electrocatalytic synthesis of HMTA involved a tandem electrochemical-chemical reaction. Additionally, the results indicated that the presence of Cu vacancies enhanced substrate adsorption and inhibited the further hydrogenation of C═N. Overall, this study provides an electrocatalytic method for HMTA synthesis and an electrochemical strategy for constructing multiple C-N bonds.

Wool fiber as an In situ reducing agent towards ZnO-based surface modified fabric development: Durability assessment in the realm of textile applications

The development of a bio-inspired method to fabricate ZnO nanostructure-modified functional wool fabric represents a substantial challenge in the textile field. This article reports for the first time the use of wool as a reducing agent for the synthesis of ZnO nanoparticles. While previous studies have employed alternative natural reducing agents for surface modification of host materials, this investigation uniquely utilizes the host material, wool, as the reducing agent for in-situ ZnO nanoparticle synthesis. In addition to demonstrating the use of wool as a reducing agent, this literature uniquely reports the durability of the modified fabric, achieved through the use of trimethoxy methyl silane. This silane compound acts as a bridging agent, forming a strong interface between the wool fibers and the synthesized ZnO nanoparticles. This innovative approach enhances the adhesion and stability of the ZnO nanoparticles on the wool fabric, a key aspect that contributes to the overall durability and performance of the modified material. The in situ surface modification process employed a metal oxide precursor (zinc acetate dihydrate), capping agents (hexamethylene tetraamine, sodium carbonate, and sodium sulfate), and a coupling agent (trimethyl methoxy silane). The capping agents were used to control the reaction conditions, while the coupling agent was employed to improve the durability of the surface modification. The impact of three different capping agents on the corresponding synthesis process was assessed, and the findings revealed that the choice of capping agent helped to form ZnO nanoparticles with distinct morphologies. Analytical techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), dynamic light scattering (DLS), and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, were utilized to characterize the synthesized particles and the treated fabric. The XRD analysis coupled with SEM analysis confirmed the successful formation of ZnO nanoparticles. The ATR-FTIR spectroscopy provided evidence of the formation of Si-O-Zn and Si-O-C bonds, observed at around 920 cm−1 and 1040 cm−1 respectively. These spectroscopic findings indicate that the surface modification involving the silane compound has enhanced the durability of the ZnO-modified fabric. The covalent linkages between the ZnO nanoparticles, the silane compound, and the wool fibers, confirmed by SEM analysis before and after washing cycles, have enabled the durable attachment of the nanoparticles to the fabric surface, even after multiple washing cycles. The results suggest a novel pathway to use wool as a reducing agent for the surface modification of the same material. Detailed mechanistic insights into the surface modification process and the corresponding chemical interactions were also discussed.

Iron Oxide-Doped Carbon Nanoparticles Stabilised with Functionally Modified Hyperbranched Polyglycerol for Cd2+ Sensing and Photodynamic Antibacterial Therapeutic Applications.

Nanoscale materials are being developed from individual particles to multi-component assemblies, with carbon nanomaterials being particularly useful in bioimaging, sensing, and optoelectronics due to their unique optical properties, enhanced by surface passivation and chemical doping. Noble metals are commonly used in conjunction with carbon-based nanomaterials for the synthesis of nanohybrids. Carbon-based materials can function as photosensitizers and effective carriers in photodynamic therapy, enabling the use of combined treatment approaches. The hydrophobicity and agglomeration tendency of carbon nanoparticles pose a drawback. This study is an attempt to overcome these limitations, which involved the synthesis of iron oxide-doped carbon nanoparticles through the carbonisation of citric acid and hexamethylene tetramine, followed by doping them with iron oxide. The as synthesized iron oxide-doped carbon nanoparticles were stabilised with fluorescently modified hyperbranched polyglycerol. The efficacy of these nanoparticles in photodynamic antibacterial therapy and Cd (II) ion sensing was investigated. The selectivity of stabilised nanoparticles against Cd2+ ion is presented in the current study. The current study also compares the antibacterial efficacy of undoped, iron oxide-doped and stabilised nanoparticle systems. The possible toxic effects of the synthesised nanosystems were investigated in order to assess their suitability for biomedical applications and establish their safety profile.

ZnO nanostructures with controlled morphological and optical properties for applications as efficient photocatalyst for malachite green degradation

This study aims to comparatively investigate the morphological and optical characteristics of zinc oxide nanoparticles as a function of the preparation conditions. A series of ZnO nanoparticles were synthesized by facile precipitation method at constant temperature, by varying the zinc sources (zinc acetate, zinc nitrate and zinc chloride) or the precipitant nature (hexamethylenetetramine, urea). The structural, morphological and optical attributes of the prepared ZnO samples were assessed by SEM, XRD, FTIR, UV–Vis and photoluminescence analyses. The morphology of the achieved samples varies from spiky sticks to hexagons or foils with irregular shapes, observing that urea favour the development of two- or three-dimensional ZnO nanostructures, while hexamethylenetetramine predominantly triggered the formation of highly organized one-dimensional structures. The XRD patterns of all ZnO samples matches zincite crystalline hexagonal phase and the evaluation of crystallite size revealed higher values for the samples prepared in the presence of hexamethylenetetramine (HMTA). The optical band gap of ZnO NPs, as estimated from the UV–Vis absorption spectra, varied slightly from 3.13 to 3.21 eV, while fluorescence investigation proves that samples prepared with urea precipitant have a lower rate of charge recombination. Tests on the photocatalytic degradation of malachite green dye under UV light irradiation demonstrated that the dynamics of photogenerated charge carriers play a significant role in the photocatalytic performance of ZnO samples.

Research and Application of Temporary Plugging Agent Technology for High-Pressure Wells in Gas Storage Facilities

Before various construction of gas storage well, in order to ensure safety, the reservoir must be temporarily blocked, degassed by circulation and no gas in the well can be operated. There are many temporary plugging methods for oil and gas wells. This paper studies the more advanced micro mesh gel temporary plugging technology in the industry and its application in gas storage wells, which mainly solves the problems of poor degradation backflow effect and difficult permeability recovery caused by weak formation stability after temporary plugging of gas storage wells. Research points: (1) On the basis of ordinary gel, through the fusion with cross-linking agent with special structure, a micron network polymer with significant steric hindrance effect on water molecules is finally formed, which improves the strength and stability of the gel system. (2) Add hexamethylene tetramine, bisphenol propane, delayed cross-linking agent and stabilizer into the polymer aqueous solution. It is verified by laboratory tests that the micron mesh gel can be formed after constant temperature coagulation for 3h~70h at ambient temperature of 90°C~170°C. (3) The temperature resistance, permeability and gel breaking of micron mesh gel are tested in the laboratory, and the results can meet the construction requirements. (4) After the temporary plugging operation of Well Su 49K-2X in the gas storage reservoir of Huabei Oilfield is completed, the degradation products of gel breaking will flow back smoothly to ensure that the well can be put into normal injection and production quickly. The test results show that: (1) Micron mesh gel has the advantages of long plugging validity, high temperature resistance, low viscosity after gel breaking, no residue, thorough gel breaking, no formation plugging pollution, and no impact on the original reservoir permeability. It is a new green plugging technology suitable for deep buried high-temperature depleted oil and gas reservoirs. (2) Before construction, the well temperature shall be measured to conduct test injection, so as to prevent gas invasion from affecting the construction effect. The pump injection displacement is designed to be redundant, so as to prevent the low molecular solution from not reaching the design position in the well on time, and the formation of solid rubber plugs at other positions in the well from affecting the construction.

Standardizing the optimal photo-diode performance of CuO nanostructures through various morphological patterns

The CuO nanocrystals were prepared using a simple surfactant-assisted co-precipitation technique then addition of anionic surfactants such as Hexamine (HEX), Polyvinyl Pyrrolidone (PVP), Polyvinyl Alcohol (PVA) and Cetyl Trimethyl Ammonium Bromide (CTAB) leads to the formation of CuO nanostructures on the surface of spherical particles. Samples were characterized via X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Field Emission Scanning Electron Microscopy (FESEM), UV–visible diffuse reflectance spectroscopy and I-V characteristics. According to various spectroscopic results, all surfactant decorated CuO nanocrystal have a monoclinic crystal structure. Then the average grain size of CuO samples supported by HEX, PVA, PVP and CTAB is approximately 72 nm. The properties of surfactants have been shown to affect size and shape. In addition, the FT-IR spectra of all samples show three similar vibration modes of CuO, this indicates the presence of a monoclinic CuO crystal structure. According to absorbance data, the quantum confinement effect caused by the use of surfactant significantly affects the optical bandgap value, ranging from 3.00 to 2.59 eV. Current-voltage characteristics [I-V] unveil the photodiode parameters of prepared diode are evaluated in the dark and light condition. In this case, the barrier height (ΦB) is 0.80 eV and the ideal value for the diode (n) is 2.05, which is more suitable for photodiode applications.

The structure of epitaxial growth of Nb-doped ZnO nanorods on intrinsic substrate via sonicated aqueous chemical method

The simplicity and abundance of water sources make water-based synthesis extremely intriguing. Nb-doped ZnO nanorods was successfully grown using a straightforward and cost-effective aqueous chemical technique. The precursor of Nb-doped ZnO comprised zinc nitrate hexahydrate, hexamethylenetetramine (HMTA), and deionized water. These substances were used as starting materials, stabilisers, and solvents, respectively. Niobium chloride served as a source of niobium dopant. The intrinsic seeded substrate was submerged in a Nb-doped ZnO precursor solution in order to facilitate the epitaxial growth of nanorods. In order to investigate the influence of the dopant percentage, the amount of Nb-dopant was varied from 0 to 0.7 at. %. The presence of Nb-doped ZnO nanorods was confirmed by the utilisation of FESEM and EDAX techniques, which allowed for the verification of both the growth of nanorods and the identification of their constituent elements. The diameter obtained is between 79.76 and 134.51 nm, depending on the amount of dopant. Since the average nanorod length is 1.1086 ± 24.9187 μm, the aspect ratio estimation is about 13.9. The atomic arrangement was investigated using high-resolution transmission electron microscopy (HRTEM). The interplanar distance of 0.264 nm corresponds to plan (002) estimated via HRTEM. The estimation is in agreement with the XRD analysis. In addition, the peak of (002) is dominant for every sample. The sharpest and highest peak can be found in 0.3 at. % of dopant. As the texture coefficient (TC) has a higher value for plan (002), crystalline growth is preferred in c-orientation.