Carbon nitride/polyimide porous film via an NIPS method with advanced dielectric and hydrophobicity properties.

Herein, an ultra-low dielectric porous polyimide (PPI) composite film was fabricated by non-solvent induced phase separation (NIPS). High-performance carbon nitride nanosheets grafted by heptadecafluoro-1,1,2,2-tetradecyl-trimethoxysilane (CNNF) were incorporated into the PPI film to enhance thermomechanical and hydrophobic properties. The effects of non-solvent and filler content on the porous morphology, dielectric properties, hydrophobicity and thermomechanical properties of films were investigated. The porous morphology of the CNNF/PPI film changed from the coexistence of pipe-like and spongy structure via H2O, to a tightly-stacked porous structure via MeOH as non-solvent. The dielectric constants ε' of 0.5 wt%-CNNF/PPI(H2O) and 0.5 wt%-CNNF/PPI(MeOH) were 1.56 and 1.69 at 1 MHz, respectively, which were ∼50% lower than that of the original PI film (ε' = 3.33). With the introduction of CNNF, the water contact angle (WCA) of CNNF/PPI(H2O) increased from 66° to 107° and that of CNNF/PPI(MeOH) increased from 92° to 120°. Simultaneously, the storage modulus E' of 2 wt%-CNNF/PPI(MeOH) reached its highest value of ∼881 MPa, which was ∼350 MPa higher than that of PPI(MeOH), together with an enhancement in Tg. This method confirmed a promising prospect for the utilization of porous PI substrates in integrated circuits and microelectronic devices.

Novel insights into the effects of 5-hydroxymethfurural on genomic instability and phenotypic evolution using a yeast model.

5-Hydroxymethfurural (5-HMF) is naturally found in a variety of foods and beverages and represents a main inhibitor in the lignocellulosic hydrolysates used for fermentation. This study investigated the impact of 5-HMF on the genomic stability and phenotypic plasticity of the yeast Saccharomyces cerevisiae. Using next-generation sequencing technology, we examined the genomic alterations of diploid S. cerevisiae isolates that were subcultured on a medium containing 1.2 g/L 5-HMF. We found that in 5-HMF-treated cells, the rates of chromosome aneuploidy, large deletions/duplications, and loss of heterozygosity were elevated compared with that in untreated cells. 5-HMF exposure had a mild impact on the rate of point mutations but altered the mutation spectrum. Contrary to what was observed in untreated cells, more monosomy than trisomy occurred in 5-HMF-treated cells. The aneuploidy mutant with monosomic chromosome IX was more resistant to 5-HMF than the diploid parent strain because of the enhanced activity of alcohol dehydrogenase. Finally, we found that overexpression of ADH6 and ZWF1 effectively stabilized the yeast genome under 5-HMF stress. Our findings not only elucidated the global effect of 5-HMF on the genomic integrity of yeast but also provided novel insights into how chromosomal instability drives the environmental adaptability of eukaryotic cells.IMPORTANCESingle-cell microorganisms are exposed to a range of stressors in both natural and industrial settings. This study investigated the effects of 5-hydroxymethfurural (5-HMF), a major inhibitor found in baked foods and lignocellulosic hydrolysates, on the chromosomal instability of yeast. We examined the mechanisms leading to the distinct patterns of 5-HMF-induced genomic alterations and discovered that chromosomal loss, typically viewed as detrimental to cell growth under most conditions, can contribute to yeast tolerance to 5-HMF. Our results increased the understanding of how specific stressors stimulate genomic plasticity and environmental adaptation in yeast.

Induction of apoptosis and autophagy by dichloromethane extract from Patrinia scabiosaefolia Fisch on acute myeloid leukemia cells.

Patrinia scabiosaefolia Fisch (PS), a perennial herb belonging to the genus Pinus in the family Pinnacle Sauce, has been previously known for its analgesic, anti-inflammatory, antibacterial, and antitumor properties. However, the specific mechanism behind its antileukemic effect remains unknown. This study focused on the cytotoxicity and potential modes of action of the dichloromethane extract from PS (DEPS) in acute myeloid leukemia (AML) cells. Our results demonstrated that DEPS reduced cell viability, arrested the cell cycle in the G2/M phase, disrupted the mitochondrial membrane potential, increased reactive oxygen species (ROS) production, and upregulated the expression of Bax/Bcl-2 and Cleaved caspase-3. However, the impact of DEPS on cell viability and the expression of apoptosis-associated proteins was reversed upon pretreatment with the caspase-3 inhibitor (Z-DEVD-FMK) in HL-60 cells, which demonstrated that DEPS could induce apoptosis through the mitochondria-associated apoptotic pathway. Interestingly, DEPS also influenced autophagy by upregulating the expression of LC3II/I, P62, and Beclin-1 proteins, and the autophagy inhibition chloroquine(CQ) could attenuate the apoptotic effects of DEPS in HL-60 cells. Furthermore, SMART 2.0 analysis predicted that the main components present in DEPS were likely terpenoids. In conclusion, DEPS possibly exerts antileukemic effects by downregulating the PI3K/AKT and ERK pathways, thereby promoting intracellular ROS production, activating the mitochondrial apoptotic pathway, and affecting autophagy, providing valuable insights for the potential future application of PS in the treatment of AML.

Reliability, Validity, and Identification Ability of a Commercialized Waist-Attached Inertial Measurement Unit (IMU) Sensor-Based System in Fall Risk Assessment of Older People.

Falls are a prevalent cause of injury among older people. While some wearable inertial measurement unit (IMU) sensor-based systems have been widely investigated for fall risk assessment, their reliability, validity, and identification ability in community-dwelling older people remain unclear. Therefore, this study evaluated the performance of a commercially available IMU sensor-based fall risk assessment system among 20 community-dwelling older recurrent fallers (with a history of ≥2 falls in the past 12 months) and 20 community-dwelling older non-fallers (no history of falls in the past 12 months), together with applying the clinical scale of the Mini-Balance Evaluation Systems Test (Mini-BESTest). The results show that the IMU sensor-based system exhibited a significant moderate to excellent test-retest reliability (ICC = 0.838, p < 0.001), an acceptable level of internal consistency reliability (Spearman's rho = 0.471, p = 0.002), an acceptable convergent validity (Cronbach's α = 0.712), and an area under the curve (AUC) value of 0.590 for the IMU sensor-based receiver-operating characteristic (ROC) curve. The findings suggest that while the evaluated IMU sensor-based system exhibited good reliability and acceptable validity, it might not be able to fully identify the recurrent fallers and non-fallers in a community-dwelling older population. Further system optimization is still needed.

Secondary lens with hybrid structure of freeform surface and microstructure for ultra-thin backlight unit.

Ultra-thin has become the development trend of the direct-lit backlight unit (BLU). Double freeform surface lenses are commonly used in direct-lit BLUs to reduce thickness. However, for an ultra-thin BLU with quite small optical distance (OD) and a large LED pitch distance, the curvature of the designed lens would be quite large, which would make the final optical performance heavily affected by fabrication errors. This paper proposes a lens with freeform surfaces and microstructures. The rays from LEDs are first collimated by the freeform surfaces and the collimated rays are then reflected by the microstructures to the bottom of the BLU, which can effectively enlarge the spot size and reduce the OD. The simulation results show that the uniformity can be improved from 41.3% of the conventional double freeform surface lens to 83% when OD is 3 mm. Such hybrid lenses can avoid the fabrication of freeform surfaces with large curvature and the advantages of easy design and easy fabrication.

Shinella sedimenti sp. nov., isolated from sediment of Zhairuo Island located in the East China Sea.

A Gram-negative, rod-shaped and aerobic bacterial strain B3.7T, was isolated from the sediment of Zhairuo Island, Zhoushan city, Zhejiang Province, PR China. Maximum growth of strain B3.7T was observed at 30 °C when cultured in a medium containing 0.5 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences demonstrated that strain B3.7T belonged to the genus Shinella; it showed the highest sequence similarity of 98.47 % to Shinella kummerowiae CCBAU 25048T. The average nucleotide identity and digital DNA-DNA hybridization values between strain B3.7T and its reference strains were 82.9-84.2 % and 26.1-27.3 %, respectively. Chemotaxonomic analysis indicated that the sole respiratory quinone was Q-10 and the predominant cellular fatty acids were C19 : 0 cyclo ω8c, C16 : 0, C18 : 1 ω7c 11-methyl and summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c). The polar lipid profile was composed of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, three unidentified phospholipids and two unidentified aminolipids. Collectively, strain B3.7T can be considered to represent a novel species, for which the name Shinella sedimenti sp. nov. is proposed. The type strain is B3.7T (=MCCC 1K07163T=LMG 32559T).

Nonlethal Furfural Exposure Causes Genomic Alterations and Adaptability Evolution in Saccharomyces cerevisiae.

Furfural is a major inhibitor found in lignocellulosic hydrolysate, a promising feedstock for the biofermentation industry. In this study, we aimed to investigate the potential impact of this furan-derived chemical on yeast genome integrity and phenotypic evolution by using genetic screening systems and high-throughput analyses. Our results showed that the rates of aneuploidy, chromosomal rearrangements (including large deletions and duplications), and loss of heterozygosity (LOH) increased by 50-fold, 23-fold, and 4-fold, respectively, when yeast cells were cultured in medium containing a nonlethal dose of furfural (0.6 g/L). We observed significantly different ratios of genetic events between untreated and furfural-exposed cells, indicating that furfural exposure induced a unique pattern of genomic instability. Furfural exposure also increased the proportion of CG-to-TA and CG-to-AT base substitutions among point mutations, which was correlated with DNA oxidative damage. Interestingly, although monosomy of chromosomes often results in the slower growth of yeast under spontaneous conditions, we found that monosomic chromosome IX contributed to the enhanced furfural tolerance. Additionally, terminal LOH events on the right arm of chromosome IV, which led to homozygosity of the SSD1 allele, were associated with furfural resistance. This study sheds light on the mechanisms underlying the influence of furfural on yeast genome integrity and adaptability evolution. IMPORTANCE Industrial microorganisms are often exposed to multiple environmental stressors and inhibitors during their application. This study demonstrates that nonlethal concentrations of furfural in the culture medium can significantly induce genome instability in the yeast Saccharomyces cerevisiae. Notably, furfural-exposed yeast cells displayed frequent chromosome aberrations, indicating the potent teratogenicity of this inhibitor. We identified specific genomic alterations, including monosomic chromosome IX and loss of heterozygosity of the right arm of chromosome IV, that confer furfural tolerance to a diploid S. cerevisiae strain. These findings enhance our understanding of how microorganisms evolve and adapt to stressful environments and offer insights for developing strategies to improve their performance in industrial applications.

Diterpenoids with an unusual tricyclo[10.3.0.02,9]pentadecane skeleton from Pedilanthus tithymaloides as multidrug resistance modulators.

Three new diterpenoids with an unusual carbon skeleton, pedilanins A-C (1-3), and nine new jatrophane diterpenoids, pedilanins D-L (4-12), along with five known ones (13-17), were isolated from Pedilanthus tithymaloides. Compounds 1-3 characterize an unprecedented tricyclo[10.3.0.02,9]pentadecane skeleton. Compounds 4-8 are rare examples of the jatrophanes bearing a cyclic hemiketal substructure. Their structures were determined by an extensive analysis of HRESIMS, NMR, quantum-chemical calculation, DP4+ probability, and X-ray crystallographic data. In the bioassay, compounds 1-12 dramatically reversed multidrug resistance in cancer cells with the fold-reversals ranging from 17.9 to 396.8 at the noncytotoxic concentration of 10 µM. The mechanism results indicated that compounds 2 and 3 inhibited the P-glycoprotein (Pgp) transporter function, thus reversing the drug resistance.

[Effect of Dichloromethane Extraction Phase of Patrinia Scabiosaefolia Fisch. Stem on Proliferation and Differentiation of K562 Cells].

OBJECTIVE: To explore the effect of dichloromethane extraction phase of ethanol extract from stem of Patrinia scabiosaefolia Fisch.(DPSS) on proliferation and differentiation of K562 cells and its related mechanism. METHODS: MTT assay was used to detect the effects of DPSS at 0, 25, 50, 100 and 200 µg/ml on the proliferation of K562 cells at 24, 48 and 72 hours. Flow cytometry was used to analyze the changes of cell cycle and apoptosis at 24 and 48 hours. Wright-Giemsa staining was used to observe the morphological changes of K562 cells. The cell surface antigens CD33 and CD11b were detected by flow cytometry. RESULTS: The proliferation of K562 cells treated with different concentrations of DPSS was inhibited in a time-dose dependent manner (r=-0.96). Cell cycle analysis showed that with the increase of DPSS concentration, cells in G2/M phase increased (r=0.88), and cells were blocked in G2/M phase. Flow cytometry results showed that with the apoptosis rate of K562 cells was the highest when treated with 200 µg/ml DPSS for 48 h. Morphological observation showed that the K562 cell body increased, the amount of cytoplasm increased, the ratio of nucleus to cytoplasm decreased, and the nuclear chromatin was rough after DPSS treatment. Cell differentiation antigen, CD33 and CD11b, were positively expressed after treated with DPSS. CONCLUSION: DPSS can induce apoptosis through cell cycle arrest, inhibit the proliferation of K562 cells, and induce K562 cells to differentiate into monocytes, which has a potential anti-leukemia effect.

Rheological Performance of High-Temperature-Resistant, Salt-Resistant Fracturing Fluid Gel Based on Organic-Zirconium-Crosslinked HPAM.

Development of low-cost, high-temperature-resistant and salt-resistant fracturing fluids is a hot and difficult issue in reservoir fluids modification. In this study, an organic zirconium crosslinker that was synthesized and crosslinked with partially hydrolyzed polyacrylamide (HPAM) was employed as a cost-effective polymer thickener to synthesize a high-temperature-resistant and salt-resistant fracturing fluid. The rheological properties of HPAM in tap water solutions and 2 × 104 mg/L salt solutions were analyzed. The results demonstrated that addition of salt reduced viscosity and viscoelasticity of HPAM solutions. Molecular dynamics (MD) simulation results indicated that, due to electrostatic interaction, the carboxylate ions of HPAM formed an ionic bridge with metal cations, curling the conformation, decreasing the radius of rotation and thus decreasing viscosity. However, optimizing fracturing fluids formulation can mitigate the detrimental effects of salt on HPAM. The rheological characteristics of the HPAM fracturing fluid crosslinking process were analyzed and a crosslinking rheological kinetic equation was established under small-amplitude oscillatory shear (SAOS) test. The results of a large-amplitude oscillation shear (LAOS) test indicate that the heating effect on crosslinking is stronger than the shear effect on crosslinking. High-temperature-resistant and shear-resistant experiments demonstrated good performance of fracturing fluids of tap water and salt solution at 200 °C and 180 °C.

Atopomonas sediminilitoris sp. nov., isolated from beach sediment of Zhairuo Island, China.

A novel bacterium designated A3.4T was isolated from the beach sediment of Zhairuo Island, which is located in the East China Sea. Strain A3.4T was found to be Gram-stain negative, cream coloured, rod-shaped, aerobic and motile via a single monopolar flagellum. The isolate grows at 20-37 °C (optimum 25-30 °C), at pH 6.0-8.0 (optimum pH 7.0-8.0), and in the presence of 0-5.0% (w/v) NaCl (optimum 0.5-1%). A3.4T has catalase and oxidase activity. The predominant fatty acids (≥ 10%) of the strain were identified as C16:0, summed feature 3 (C16:1 ω7c /C16:1 ω6c) and summed feature 8 (C18:1 ω7c /C18:1 ω6c). Q-9 was identified as the major isoprenoid quinone, with trace levels of Q-8 present. The major polar lipids were identified as diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol. The draft genome size is 3.55 Mb, with a DNA G + C content of 57.7 mol%. Analysis of the 16S rRNA gene sequence of strain A3.4T indicates that it belongs to the genus Atopomonas and shares high sequence similarity with Atopomonas hussainii JCM 19513T (97.60%). This classification was also supported by phylogenetic analysis using rpoB and several core genes. The genome of strain A3.4T shows an average nucleotide identity of 82.3%, an amino acid identity of 83.0%, and a digital DNA-DNA hybridization value of 22.1% with A. hussainii. In addition, 20 conserved signature indels (CSIs) were identified to be specific for A3.4T and A. hussainii, demonstrating that the strain A3.4T is closely related to A. hussainii rather than other species of family Pseudomonadaceae. Hundreds of unique genes were identified in the genomes of A3.4T and A. hussainii, which may underly multiple phenotypic differences between these strains. Based on phenotypic, chemotaxonomic, phylogenetic, and genomic investigations, strain A3.4T is concluded to represent a novel species of the genus Atopomonas, for which the name Atopomonas sediminilitoris sp. nov. is proposed. The type strain is A3.4T (= LMG 32563T = MCCC 1K07166T).

Ancylobacter gelatini sp. nov., isolated from beach sediment of Zhairuo Island, China.

A Gram-negative, aerobic, non-motile, oxidase-positive, catalase-positive, methyl red-positive, and lipase-negative bacterium, designated A5.8T, was isolated from beach sediment of Zhairuo Island located in the East China Sea. Growth occurred at 10-40 °C (optimum, 30 °C), pH 5.5-9.5 (optimum, 7.5), and 0-2% NaCl (optimum, 1.5%). Based on 16S rRNA gene sequence analysis, strain A5.8T belongs to the genus Ancylobacter, sharing the highest similarity with Ancylobacter aquaticus JCM 20518T (98.0%). Its polar lipids mainly consist of phosphatidylethanolamine (PE) and phosphatidylcholine (PC). The predominant fatty acids are summed feature 8 (C18:1ω7c and/or C18:1ω6c, 91.0%), and the major respiratory quinone is Q-10. The DNA G + C content is 67.2 mol%. Based on above analysis, as well as digital DNA-DNA hybridization (22.5-22.9%) and average nucleotide identity (83.0-83.6%) of strain A5.8T with reference type strains of the genus Ancylobacter, strain A5.8T was suggested to represent a novel species of the genus Ancylobacter, for which the name Ancylobacter gelatini sp. nov. is proposed. The type strain is A5.8T (= MCCC 1K07167T = LMG 32566T).

Spectrins and human diseases.

Spectrin, as one of the major components of a plasma membrane-associated cytoskeleton, is a cytoskeletal protein composed of the modular structure of α and ß subunits. The spectrin-based skeleton is essential for preserving the integrity and mechanical characteristics of the cell membrane. Moreover, spectrin regulates a variety of cell processes including cell apoptosis, cell adhesion, cell spreading, and cell cycle. Dysfunction of spectrins is implicated in various human diseases including hemolytic anemia, neurodegenerative diseases, ataxia, heart diseases, and cancers. Here, we briefly discuss spectrins function as well as the clinical manifestations and currently known molecular mechanisms of human diseases related to spectrins, highlighting that strategies for targeting regulation of spectrins function may provide new avenues for therapeutic intervention for these diseases.

Uncovering Bleomycin-Induced Genomic Alterations and Underlying Mechanisms in the Yeast Saccharomyces cerevisiae.

Bleomycin (BLM) is a widely used chemotherapeutic drug. BLM-treated cells showed an elevated rate of mutations, but the underlying mechanisms remained unclear. In this study, the global genomic alterations in BLM-treated cells were explored in the yeast Saccharomyces cerevisiae. Using genetic assay and whole-genome sequencing, we found that the mutation rate could be greatly elevated in S. cerevisiae cells that underwent Zeocin (a BLM member) treatment. One-base deletion and T-to-G substitution at the 5'-GT-3' motif represented the most striking signature of Zeocin-induced mutations. This was mainly the result of translesion DNA synthesis involving Rev1 and polymerase ζ. Zeocin treatment led to the frequent loss of heterozygosity and chromosomal rearrangements in the diploid strains. The breakpoints of recombination events were significantly associated with certain chromosomal elements. Lastly, we identified multiple genomic alterations that contributed to BLM resistance in the Zeocin-treated mutants. Overall, this study provides new insights into the genotoxicity and evolutional effects of BLM. IMPORTANCE Bleomycin is an antitumor antibiotic that can mutate genomic DNA. Using yeast models in combination with genome sequencing, the mutational signatures of Zeocin (a member of the bleomycin family) are disclosed. Translesion-synthesis polymerases are crucial for the viability of Zeocin-treated yeast cells at the sacrifice of a higher mutation rate. We also confirmed that multiple genomic alterations were associated with the improved resistance to Zeocin, providing novel insights into how bleomycin resistance is developed in cells.

Acinetobacter sedimenti sp. nov., isolated from beach sediment.

A Gram-stain-negative, aerobic, non-motile, non-haemolytic, oxidase-negative, catalase-positive bacillus strain (A3.8T) was isolated from beach sediment from Zhairuo Island, PR China. The strain grew at pH 6.0-9.0 (optimum, 7.0), with 0-4.5 % NaCl (optimum, 2 %) and at 10-35 °C (optimum, 30 °C). Its whole-genome sequence was 2.5 Mb in size, with a DNA G+C content of 41.6 mol%. On the basis of the results of core genome phylogenetic analysis, A3.8T represents a separate branch within the clade formed by five species of the genus Acinetobacter with 'Acinetobacter marinus' as the most closely related species. The average nucleotide identity compared with the closely related species of the genus Acinetobacter was below 83.66 % and digital DNA-DNA hybridization values were less than 28.80 %. The predominant fatty acids included C18 : 1ω9c, C16 : 0 and summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c). Q-9 was the major respiratory quinone. The polar lipids are mainly composed of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, two phospholipids, an aminolipid and four unknown lipids. A3.8T cannot assimilate dl-lactate and weakly utilizes l-glutamate, l-leucine, l-phenylalanine and l-tartrate, which distinguishes it from other species of the genus Acinetobacter. On the basis of the genotype, phenotype and biochemical data, strain A3.8T represents a novel species of the genus Acinetobacter, for which the name Acinetobacter sedimenti sp. nov. is proposed. The type strain is A3.8T (=MCCC 1K07161T=LMG 32568T).

Coaxial electrospun aligned tussah silk fibroin nanostructured fiber scaffolds embedded with hydroxyapatite-tussah silk fibroin nanoparticles for bone tissue engineering.

The bone is a composite of inorganic and organic materials and possesses a complex hierarchical architecture consisting of mineralized fibrils formed by collagen molecules and coated with oriented hydroxyapatite. To regenerate bone tissue, it is necessary to provide a scaffold that mimics the architecture of the extracellular matrix in native bone. Here, we describe one such scaffold, a nanostructured composite with a core made of a composite of hydroxyapatite and tussah silk fibroin. The core is encased in a shell of tussah silk fibroin. The composite fibers were fabricated by coaxial electrospinning using green water solvent and were characterized using different techniques. In comparison to nanofibers of pure tussah silk, composite notably improved mechanical properties, with 90-fold and 2-fold higher initial modulus and breaking stress, respectively, obtained. Osteoblast-like MG-63 cells were cultivated on the composite to assess its suitability as a scaffold for bone tissue engineering. We found that the fiber scaffold supported cell adhesion and proliferation and functionally promoted alkaline phosphatase and mineral deposition relevant for biomineralization. In addition, the composite were more biocompatible than pure tussah silk fibroin or cover slip. Thus, the nanostructured composite has excellent biomimetic and mechanical properties and is a potential biocompatible scaffold for bone tissue engineering.

A simple fluorescent probe for the determination of dissolved oxygen based on the catalytic activation of oxygen by iron(II) chelates.

This work aims at establishing a simple fluorescent probe for the determination of dissolved oxygen. It is found that iron(II) ions activate oxygen to produce reactive species being capable of oxidizing non-fluorescent coumarin to fluorescent 7-hydroxycoumarin. However, this process is not effective because the yield of the reactive species is very low in the presence of simple iron(II) salts alone. The addition of organic ligands such as oxalate results in the formation of complexes between iron(II) ions, which leads to considerable increase in the yield of reactive species (such as hydroxyl radicals) and then increase in the fluorescence intensity of 7-hydroxycoumarin to a significant level. It has been observed that in the mixture solution of iron(II) ions, ligand, coumarin, and dissolved oxygen, there is an excellent linear response between the fluorescence and dissolved oxygen. Therefore, a new spectrofluorimetric method has been proposed for the determination of dissolved oxygen by using catalytic activation of O(2) by iron(II) chelates. Under optimized conditions, a linear correlation (r=0.995) has been observed between the fluorescence intensity of 7-hydroxycoumarin at 456 nm and the concentration of dissolved oxygen over the range of 0.96-9.22 mg L(-1). The limit of detection for dissolved oxygen at a signal-to-noise ratio of 3 has been estimated to be 0.35 mg L(-1). The proposed method has been applied to determine the concentration of dissolved oxygen in practical water samples with results as satisfactory as that obtained by the standard iodometric method.