Oxygen Deficiency Research Articles

Bi2S3/Ti3C2-TPP nano-heterostructures induced by near-infrared for photodynamic therapy combined with photothermal therapy on hypoxic tumors

BackgroundPhotodynamic therapy (PDT) efficacy of bismuth sulfide (Bi2S3) semiconductor has been severely restricted by its electron–hole pairs (e−−h+) separation inefficiency and oxygen (O2) deficiency in tumors, which greatly hinders reactive oxygen species (ROS) generation and further clinical application of Bi2S3 nanoparticles (NPs) in biomedicine.ResultsHerein, novel Bi2S3/titanium carbide (Ti3C2) two-dimensional nano-heterostructures (NHs) are designed to realize multimode PDT of synchronous O2 self-supply and ROS generation combined with highly efficient photothermal tumor elimination for hypoxic tumor therapy. Bi2S3/Ti3C2 NHs were synthesized via the in situ synthesis method starting from Ti3C2 nanosheets (NSs), a classical type of MXene nanostructure. Compared to simple Bi2S3 NPs, Bi2S3/Ti3C2 NHs significantly extend the absorption to the near-infrared (NIR) region and enhance the photocatalytic activity owing to the improved photogenerated carrier separation, where the hole on the valence band (VB) of Bi2S3 can react with water to supply O2 for the electron on the Ti3C2 NSs to generate ·O2− and ·OH through electron transfer. Furthermore, they also achieve 1O2 generation through energy transfer due to O2 self-supply. After the modification of triphenylphosphium bromide (TPP) on Bi2S3/Ti3C2 NHs, systematic in vitro and in vivo evaluations were conducted, revealing that the synergistic-therapeutic outcome of this nanoplatform enables complete eradication of the U251 tumors without recurrence by NIR laser irradiation, and it can be used for computed tomography (CT) imaging because of the strong X-ray attenuation ability.ConclusionThis work expands the phototherapeutic effect of Bi2S3-based nanoplatforms, providing a new strategy for hypoxic tumor theranostics.

Oxygen vacancies-tuned BiOBr nanosheets for accelerating CO2 and Cr(VI) photoreduction

Unsatisfactory charge separation ability and insufficient active sites are the main factors leading to low efficiency for photocatalytic CO2 conversion and Cr(VI) reduction. Constructing surface defects to accelerate charge separation is an effective strategy for promoting photocatalytic process. Herein, the oxygen vacancies modulated BiOBr nanosheets were constructed by NaBH4 solution treatment. Density functional theory calculation results found that the formed oxygen vacancies would increase the electron density around Bi atoms near the oxygen vacancies, and inhibiting recombination of the photoinduced carriers. Besides, abundant oxygen vacancies can effectively enhance the adsorption of CO2 molecules. Therefore, the BiOBr with rich oxygen vacancies (BiOBr-ROV) shows higher evolution rates for CO (15.66 μmol g−1) and CH4 (0.22 μmol g−1) under irradiation of 300 W Xe lamp for 4 h compared with pristine BiOBr nanosheets (BiOBr) and BiOBr with deficient oxygen vacancies (BiOBr-DOV). The intermediate products in the CO2 reduction process have been detected by in-situ Fourier-transform infrared spectroscopy. Besides, the photodegradation activity of Cr(VI) over BiOBr-ROV is 98.65% under 80 min of irradiation, which is higher than that of BiOBr (78.01%) and BiOBr-DOV (53.67%). The work provides a new possibility to construct photocatalysts with high-performance for solar energy conversion.

NanoGuard: Antibacterial marvels of strontium titanate – Synthesis, characterization, and multifunctional insights

This study presents a comprehensive exploration into the synthesis and multifaceted characterization of strontium titanate (ST) nanopowder via the solution combustion method. The investigation delves into the photoluminescent properties, electrochemical behaviors assessed through potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS), as well as antibacterial characteristics of the synthesized nanoproduct. Through meticulous analysis involving powder X-ray diffraction (PXRD), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FT-IR), and UV–visible spectroscopy (UV–vis), ST nanoparticles revealed intriguing features. PXRD unveiled a cubic crystal structure with a crystallite size of ∼ 11 nm, showcasing a crystallinity of 89.23. FESEM, UV–visible spectroscopy, and FT-IR studies uncovered irregularities in size, band gap properties, and the formation of M−O bonds within ST, with an Eg value of ∼ 3.0 eV. Photoluminescence investigations highlighted oxygen deficiencies within the ST material. Furthermore, corrosion inhibition efficiency was evaluated, demonstrating a maximum of 81.9 % at a concentration of 400 ppm, while antibacterial studies exhibited promising results against both Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacteria, with zone of inhibitions (ZOI) measuring 8.00 ± 0.250 mm and 9.00 ± 0.000 mm, respectively. These findings collectively underscore the diverse potential applications of ST nanoparticles and offer valuable insights into their structural, optical, electrochemical, and antimicrobial properties.

Exploration of the role of oxygen-deficiencies coupled with Ni-doped V2O5 nanosheets anchored on carbon nanocoils for high-performance supercapacitor device

Electronic structural engineering via integration of oxygen deficiencies and a variety of dopants in metal oxide electrodes has fascinated the research interest for developing next-generation supercapacitors. Herein, by incorporating Ni dopants and creating O vacancies, it has thoroughly been explored the potential of vanadium oxide (V2O5) nanosheets anchored on the carbon nanocoils (CNCs) grown on nickel foam (NF) for supercapacitor electrodes (OV-Ni-V2O5/CNCs/NF). We validate a synergistic effect provided by heterostructure designed with multifunctional nano geometries. It is found that O vacancies and Ni dopants alter the electronic states of V2O5 with enhanced electrical conductivity and enriched redox active sites. We optimized O vacancies and achieved a specific capacity of 3485F g−1 (1742.5C g−1) at 1 A/g, representing ∼ 3.8 × higher compared to the best prior report. Furthermore, an asymmetric supercapacitor device was assembled with binder-free electrodes, using O0.075-V2O5/CNCs/NF as a cathode and sulfur-doped CNCs as an anode, which delivered a high energy density of 144 W h kg−1 and long-term stability of 5000 cycles, which is superior to most of the previous studies. This study paves a rational strategy to design high-performance electrodes for next-generation supercapacitors and other energy storage technologies.

Soft synthesis and analysis of structural parameters upon photoactivity of visible-active BiVO4-based ternary heterojunctions

Cu2O/Pt–BiVO4 and Cu2O/Au–BiVO4 photocatalysts are synthesized using a mild reducing agent (ascorbic acid) by an in-situ chemical reduction method at 25 °C. Pt and Au nanoparticles with an approximate size from 15 to 25 nm were incorporated onto BiVO4 powders. Crystalline phases are refined with the Rietveld method to evidence whether structural parameters contribute to enhance the photoactivity of the composites. The influences of structural defects and deposited metal are investigated to establish a relationship with their photoactivities. The as-synthesized BiVO4-based ternary photocatalysts displayed a strong optical absorption from UV to visible light shorter than 514 nm, with a blue-shift compared to that of pure BiVO4, resulting from the addition of the Au and Pt nanoparticles. The photocatalytic activities of the as-synthesized materials are evaluated under visible-light irradiation using the mineralization of 4-chlorophenol (4-CP) and dicloxacillin (DCX). The mineralization percentages achieved with Cu2O/Pt-BVO4 and Cu2O/Au–BiVO4 after 240 min of irradiation were 85% for 4-CP and 33% for DCX. It is assumed that those levels of TOC removal are due to the lowest content of oxygen vacancies in the photocatalysts, decreasing hole trapping, and subsequently hindering their recombination with the photoexcited electrons. Under this premise, structural defects (i.e. oxygen deficiency) present a more important effect on the photoactivity of the BiVO4-based materials than crystallite size, or other structural parameters. Moreover, the activity can also be ascribed to the Z-scheme Cu2O/BiVO4 heterojunction enhancing redox potentials of charge carriers, the incorporation of Pt and Au nanoparticles, enhancing charge separation either by trapping photo-generated electrons, generating the electron sink effect.

Sol-gel derived SiOx:TiOy films for integrated optics: HR S/TEM and AES/XPS insight to structure and chemical composition

Comprehensive studies on SiOx:TiOy composite waveguide layers with a high refractive index (n = 1.8), synthesized through sol–gel and dip-coating techniques are presented. The layers' structural and microchemical properties are determined using methods with different spatial resolutions (nm/μm/mm) and information depths (surface/bulk): optical transmittance, ellipsometry, transmission electron microscopy, Raman spectroscopy, Auger electron spectroscopy combined with ion profiling, and X-ray photoelectron spectroscopy. In the SiOx:TiOy films, 5 nm). Different Si- and Ti-rich phase formation mechanisms linked to alkoxide oxidation rates are found. The film composition (x = 1.1, y = 2.1) and homogenous in-depth O, Ti, and Si concentration profiles were determined. The Si/(Ti + Si) = 0.5 matching the synthesis procedure, oxygen deficiency (O/(Ti + Si) = 1.66), and oxygen vacancies in the silica phase are observed, with AES/XPS chemical shifts providing insights into bonding configurations. The SiOx:TiOy structural/chemical properties correlate well with exceptional optical film features.

Visible room-temperature emission and excitation photoluminescence in In+- and As+-co-implanted SiO2 films

The visible room-temperature emission and excitation photoluminescence spectra were studied as a function of the indium and arsenic profiles in the In+ and As+ ion-implanted thermally grown SiO2 films before and after the annealing at the temperature of 900 °C. As+ ions at the energy of 40 or 135 keV and In+ ions at the energy of 50 keV, providing a projective range ratio RpAs/RpIn of 1 or 3, respectively, were used. Four emission photoluminescence bands, peaked at ∼347 nm (3.57 eV), ∼440 nm (2.81 eV), ∼450 nm (2.75 eV) and ∼500 nm (2.48 eV), were obtained from the 40 keV As+ and 50 keV In+ ion-implanted samples under the excitation wavelength of 300 nm (4.13 eV), 350 nm (3.54 eV), 400 nm (3.10 eV) and 450 nm (2.75 eV), respectively. As the As+ energy increased to 135 keV, under the same excitation conditions, the emission bands peaked at 370 nm (3.35 eV), 420 nm (2.95 eV), 460 nm (2.69 eV) and 505 nm (2.45 eV) dominated in the photoluminescence spectra. The excitation spectra of the observed emission peaks were studied, too. We preliminarily interpret the observed photoluminescence peaks as a result of the T1 → S0 transition of molecular-like clusters associated with the oxygen deficiency provided by In or In–As in ion-implanted SiO2.

Stoichiometry of ZnO polycrystalline layers. Localization of vacancies

Nonstoichiometric ZnO1-x phases with oxygen deficiency at grain boundaries (GBs) in polycrystalline ZnO layers are a typical damaged layer formed during the synthesis or subsequent storage. In this case, the processes of adsorption-desorption of gases are the basic phenomenon used in the analysis of gas composition. MGB layers also play an important role in creating transparent electrodes for transparent electronics and optoelectronics devices. This makes it relevant to study the generalization of research data on non-stechiometric structures in various applications. Purpose: the research carried out is devoted to the analysis of the formation processes of non-stoichiometric ZnO1-x surface phases in gas sensors, transparent electrodes, ceramic targets for magnetron sputtering, and in light-emitting structures. Research is aimed at finding ways to control and optimizing the parameters of non-stoichiometric ZnO1-x phases. The structural features, electrical, optical, and emissive properties of the layers were studied depending on the stoichiometry of the material. The issues of transformation of the structure of grain boundaries in ZnO-based polycrystalline layers depending on the formation conditions and external influences are considered. The relationship between the mechanisms of carrier transport and the processes of formation of nonstoichiometric phases on the MG has been studied. The dependences of the luminescence spectra of ZnO layers on the density of oxygen vacancies were traced. The regularities of the formation of energy structures of magnetic grains in ZnO layers are considered. Establishment of patterns of formation and characteristics of non-stoichiometric phases on the MGB during the formation of various modifications of transparent electrodes. Study of ways to optimize the parameters of surface non-stoichiometric layers.

POTENTIAL THREATS TO THE ECOLOGICAL STATE OF WATER IN THE SEVASTOPOL BAY

The purpose of the work is to discuss the main environmental problems of the state of waters in the Sevastopol Bay and to identify the causes affecting their quality. Four seasonal surveys of the Sevastopol Bay water area in 2022 confirmed the prime impact of the Black River runoff, a main source of nutrients, on the hydrochemical composition of the bay waters.At the same time, it is noted that the hydrochemical parameters of the South Bay waters are predominantly affected by freshwater runoff in the estuarine part of the area rather than by the Black River water. It is assumed that the runoff is permanent, and not emergency, as previously thought. With the winds of the southern directions, the spread of the South Bay water to the central part of the Sevastopol Bay is possible, thus affecting the state of its ecosystem.In summer an additional source of ammonium ions was recorded in the estuarine part of the Artillery Bay, next to which the Crystal city beach is located, with concentrations 80 times higher than the background. Since ammonium is a product of organic matter oxidation, its appearance may indicate the predominance of destructive processes, which affect living conditions of biological organisms and, in general, the ecological state of waters. In the warm season a constant deficiency of oxygen was observed in the bottom waters of an artificial depression under the floating dock, which in some cases leads to the formation of hydrogen sulfide. All detected threats affect the ecological state of entire ecosystem of the bay, the living conditions of biological organisms and the recreational potential of the bay

A Three-Dimensional Spatial Interpolation Method and Its Application to the Analysis of Oxygen Deficit in the Bohai Sea in Summer

Dissolved oxygen (DO) plays a pivotal role in sustaining marine ecosystems. The Bohai Sea in China is a semi-enclosed sea, and oxygen-deficit events occur from time to time due to human activities. At present, there is a notable absence of any convenient and precise method for obtaining three-dimensional spatial data on DO, and the exploration of the physical mechanisms influencing oxygen deficit remains incomplete. This investigation uses the linear radial basis function (RBF-Linear) fitting method to conduct three-dimensional spatial interpolation for DO, which demonstrates minimal inaccuracy. Then, the RBF-Linear fitting method is utilized to collect a comprehensive three-dimensional spatial dataset encompassing temperature, salinity, and DO in the Bohai Sea in August from 2016 to 2018. The results indicate discernible interannual variations in the extent, area, and distribution of oxygen deficiency during summer in the Bohai Sea. Mechanism analysis reveals that intense precipitation episodes and an increase in wind stress curl exacerbate oxygen depletion. Additionally, the degree, location, and area of the two oxygen-deficit cores (off the Yellow River Estuary and off the Qinhuangdao) in the Bohai Sea are influenced by several factors, including current velocity, direction, local circulation position, and net horizontal transport rate. Furthermore, the study suggests that oxygen deficiency in the Bohai Sea region is currently in its early stages, with a limited degree of injury and a restricted range of influence. The use of a three-dimensional spatial interpolation method to create a complete DO field in three-dimensional space simplifies the research challenges associated with marine oxygen deficit. Moreover, this study holds particular significance for guiding the development of marine fisheries.

Summer heatwaves on the Baltic Sea seabed contribute to oxygen deficiency in shallow areas

Since the early 1980ies, the shallow and brackish Baltic Sea, located in northern Europe, has warmed fastest of all the world’s coastal seas. Hence, the total heat exposure during marine heatwaves increased in frequency and duration, which may have a major impact on the marine ecosystem. We found that marine heatwaves, using two different, commonly used definitions, occurred everywhere on the sea surface since the early 1990s. Periods with sea surface temperatures larger than 20 °C lasting longer than 10 days were particularly numerous in the shallow coastal zone of the southern and eastern Baltic Sea. Furthermore, summer marine heatwaves that reached the seabed mainly occurred in water depths of less than 20 m, where they led to a decrease in oxygen concentration. Since the early 1990s, a positive trend in the expansion of marine heatwaves has been observed on the seabed. The increasing number of marine heatwaves increases the risk of hypoxia events in the coastal zone.

Improving the endurance for ferroelectric Hf0.5Zr0.5O2 thin films by interface and defect engineering

Improving the endurance performance for hafnia-based ferroelectric thin films and devices is of considerable significance from both scientific and technological perspectives. Here, we obtained robust ferroelectricity in Hf0.5Zr0.5O2 (HZO) thin films without the need of the confinement from top electrodes by systematically optimizing the conditions and parameters for the post-deposition annealing (PDA) process. Compared with the post-metallization annealing (PMA) process, PDA is found to markedly improve the ferroelectric endurance performance. In particular, wake-up-free ferroelectric HZO thin films with an exceptional endurance performance (∼3 × 1010 cycles) are obtained by PDA processing conducted under an oxygen atmosphere, which is attributed to the suppression of oxygen deficiency in the HZO thin films and the inhibition of interfacial reaction layer that inevitably forms during annealing treatment for PMA processing. Our work offers insight into improving ferroelectricity and endurance for hafnia-based ferroelectric materials and devices.

Influence of Nd doping on the structural and electrochemical properties of uranium dioxide

The influence of the Nd-doping ratio and oxygen vacancies on the structural properties and electrochemical reactivity of U1-yNdyO2-x (x ≈ y/2, y = 0.02, 0.06, and 0.1) solid solutions was investigated using X-ray diffraction, Raman spectroscopy, and cyclic voltammetry. Defect structures induced by oxygen vacancies were observed with Raman spectroscopy, which showed that Raman modes shifted to higher wavenumbers with increasing doping ratio. This result is indicative of a crystal lattice disorder caused by oxygen vacancies. The wavenumber shifts and relative ratios of the Raman modes were indicators of the composition and oxygen vacancies, respectively, of the U1-yNdyO2-x solid solutions. The oxygen deficiencies of the solid solutions were estimated from the relation between the doping ratio and lattice parameter calculated from X-ray diffraction patterns. Cyclic voltammetry revealed that changes in the Nd content influenced the electrochemical reactivity of hypo-stoichiometric U1-yNdyO2-x, which increased with increasing Nd content. The results of this study provide fundamental data to improve the understanding of spent nuclear fuel.

Bipolar Plasticity in Synaptic Transistors: Utilizing HfSe2 Channel with Direct-Contact HfO2 Gate Dielectrics

The investigation of dual-mode synaptic plasticity was conducted in thin-film transistors (TFTs) featuring an HfSe2 channel, coupled with an oxygen-deficient (OD)-HfO2 layer structure. In these transistors, the application of negative gate pulses resulted in a notable increase in the post-synaptic current, while positive pulses led to a decrease. This distinctive response can be attributed to the dynamic interplay of charge interactions, significantly influenced by the ferroelectric characteristics of the OD-HfO2 layer. The findings from this study highlight the capability of this particular TFT configuration in closely mirroring the intricate functionalities of biological neurons, paving the way for advancements in bio-inspired computing technologies.

The potential of aryl hydrocarbon receptor as receptors for metabolic changes in tumors.

Cancer cells can alter their metabolism to meet energy and molecular requirements due to unfavorable environments with oxygen and nutritional deficiencies. Therefore, metabolic reprogramming is common in a tumor microenvironment (TME). Aryl hydrocarbon receptor (AhR) is a ligand-activated nuclear transcription factor, which can be activated by many exogenous and endogenous ligands. Multiple AhR ligands can be produced by both TME and tumor cells. By attaching to various ligands, AhR regulates cancer metabolic reprogramming by dysregulating various metabolic pathways, including glycolysis, lipid metabolism, and nucleotide metabolism. These regulated pathways greatly contribute to cancer cell growth, metastasis, and evading cancer therapies; however, the underlying mechanisms remain unclear. Herein, we review the relationship between TME and metabolism and describe the important role of AhR in cancer regulation. We also focus on recent findings to discuss the idea that AhR acts as a receptor for metabolic changes in tumors, which may provide new perspectives on the direction of AhR research in tumor metabolic reprogramming and future therapeutic interventions.

Structure and functioning of plankton communities оf the Rybinsky Reservoir under the conditions of climate change

Based on the data of complex environmental studies, which have been regularly carried out at six standard stations of the Rybinsk Reservoir since the middle of the 20th century, the orientation of changes in the elements of the reservoir ecosystem associated with global climatic events has been analyzed. During the period of climate warming, which began in 1977 and continues into the 21st century, the air temperature in the warm season increased by 0.9°C, the water temperature by 1.4°C, the average annual inflow by 7.5%, and the duration of the ice-free period by two weeks. An increase in electrical conductivity and color of water, a decrease in transparency were noted. With significant interannual variations in biological characteristics, in the XXI century, the number of bacterioplankton increased by 1.7 times, and bacterial production doubled. Chlorophyll content increased by 1.4 times and values 15 µg/L reflecting the eutrophic state of the reservoir began to be observed more often. In the biomass of phytoplankton, the proportion of small cell forms increased. The total abundance of phytoplankton increased due to the development of cyanobacteria, which form a long summer maximum in the seasonal dynamics of the community. The increase in water mineralization promoted the progressive spread of alien brackish-water algae. Biomass of zooplankton increased by 2.5 times. An increase in the abundance of crustaceans (Cladocerans, by 1.6 times; Copepods, by 1.9 times) caused a change in the structure of zooplankton and the formation of a strong late summer peak of biomass. The intensification of hydrobiological processes was clearly manifested after the abnormally hot 2010, the conditions of which not only stimulated the development of plankton communities, but also but also caused the formation of oxygen deficiency in the bottom layers. Warming has significantly transformed the ecosystem of the Rybinsk Reservoir, intensified eutrophication processes and worsened water quality. Changes in hydrometeorological characteristics have gone beyond the mild scenario of climate warming.

Metabolic profiling of leaves of four <i>Ranunculus</i> species

BACKGROUND: Plant ability to survive oxygen deficiency is associated with the presence of various adaptations, majority of which are mediated by significant changes of metabolism. These alterations allow resistant wetland plants to grow even in an oxygen-depleted environment.
 AIM: To compare metabolic profiles of the leaves of the wetland species Ranunculus lingua, R. repens and R. sceleratus, and the mesophyte species R. acris growing in their natural habitat in order to identify the most characteristic metabolic traits of hypoxia-resistant plants.
 MATERIALS AND METHODS: Metabolite profiling was performed by GC-MS. Statistical analysis of metabolomics data was processed using R 4.3.1 Beagle Scouts.
 RESULTS: The resulting profile included 360 compounds. 74 of these were identified and 114 compounds were determined to a class. Sugars (114) were the most widely represented in the obtained profiles. 10 amino and 23 carboxylic acids, lipids and phenolic compounds have been identified. Significant differences were revealed between the profiles of leaf metabolomes of all tested species, which were clustered according to phylogenetic relation. The hydrophytic R. sceleratus, growing under submergence, showed the most unique metabolome, in which the level of sugars was reduced and intermediates of anaerobic metabolism, nitrogen metabolism, and alternative pathways of NAD(P)H reoxidation were accumulated. The profile of mesophytic R. acris was markedly different by decreased levels of amino acids, fatty acids and sterols. The metabolite profiles of waterlogged hydrophytes R. lingua and R. repens occupied an intermediate position.
 CONCLUSIONS: The identified differences of metabolomes of Ranunculus species are due to genetic determinants, ecological niche and direct impact of a stressor.

The peculiarities of cell elongation growth of cereal coleoptiles under normal and flooding conditions

The review examines modern knowledge on the mechanisms of the early stages of plant cell elongation growth. Coleoptiles are used as a model object representing juvenile organs of cereal seedlings. Elongation growth is considered to be a protective morphophysiological stage of seedling development during hypogeal germination. The molecular mechanisms of elongation growth include: changes in the properties of the cell wall, activation of proton pumps, as well as aquaporins of plasma membrane and tonoplast. Particular attention is paid to the hormonal system of regulation, including auxin and ethylene. Coleoptiles of rice, a semi-aquatic plant tolerant to oxygen deficiency, demonstrate that the mechanisms of elongation growth are changing intensively under submergence, but they completely ensure cell growth. There is also a redistribution of importance and abundance between phytohormones. The data presented in the review indicate the necessity to continue investigations on the mechanisms of elongation growth under normal and stress conditions.

Impact of oxygen deficiency and shallow hole-traps on high-responsivity ZnO-based UV photodetectors

In this study, zinc oxide (ZnO) films have been investigated as potential high-responsivity, low-cost ultraviolet (UV) detection materials for biomedical applications. Fabricated using radiofrequency (RF) sputtering and rapid thermal annealing (RTA), ZnO films exhibit a high band gap energy (∼3.25 eV) and minimal oxygen deficiency after RTA at 400 °C. These properties significantly influence the UV detection capabilities of the films. Metal-semiconductor-metal (MSM) type UV photodetectors (PDs) constructed from these films demonstrate a high responsivity for UV-A/B detection (∼3.15 kA/W at 340 nm), which is associated with shallow hole-related traps caused by the oxygen deficiency. By applying the Arrhenius equation, two primary shallow hole traps at 37 and 241 meV were identified. The findings of this study can contribute to the development of ZnO-based UV detectors and provide insights into their temperature-dependent properties and persistent photoconductivity effects.

EFEKTIFITAS TEKNIK PERNAPASAN BUTEYKO UNTUK MENINGKATKAN PENGONTROLAN ASMA BRONKIAL DI PUSKESMAS KOTA PADANG

ABSTRACT
 Bronchial asthma is one of the chronic respiratory diseases caused by the narrowing of the airways due to hypersensitivity reactions in the bronchi, resulting in symptoms such as wheezing, coughing, and shortness of breath. When asthma patients experience breathlessness, there is an increase in respiratory frequency and a decrease in oxygen saturation. If not promptly treated, it can lead to oxygen deficiency (hypoxia), which can ultimately result in death. The management of bronchial asthma is typically done with pharmacological therapy aimed at achieving a normal lifestyle, avoiding attacks, and restoring optimal lung function. However, it has not shown significant improvement in preventing bronchial asthma. Non-pharmacological treatment methods, such as Buteyko breathing technique, are expected to complement pharmacological treatment in reducing the frequency of asthma attacks (exacerbations). The Buteyko breathing technique has shown an increase in peak expiratory flow rate (PEFR) values and a decrease in bronchial asthma score values. The objective of this study is to analyze the effectiveness of the Buteyko breathing technique in controlling bronchial asthma in the Padang Health Center area. Before the intervention, the average bronchial asthma control was 15.44, with a standard deviation of 2.279, and a minimum control of 11 and a maximum of 19. After the intervention, the average control increased to 21.69, with a standard deviation of 2.387, and a minimum control of 16 and a maximum of 25. Similarly, bronchial asthma control in the control group showed an increase from 16.19 to 15.38 after the intervention. Statistical tests using independent t-tests showed a significant influence of the Buteyko breathing technique on bronchial asthma control, with a p-value of 0.000 (p?0.05). This indicates that the Buteyko breathing technique has a significant impact on improving bronchial asthma control. Therefore, this research provides evidence that the Buteyko breathing technique can be a valuable addition to the treatment of bronchial asthma, helping patients achieve better control of their condition and reducing the risk of asthma attacks.
 Keywords: Buteyko breathing technique; Breathing patterns.