Simultaneous denitrification and hexavalent chromium removal by a newly isolated Stenotrophomonas maltophilia strain W26 under aerobic conditions

2021 ◽  
Vol 18 (1) ◽  
pp. 20
Author(s):  
Qiang An ◽  
Shu-man Deng ◽  
Bin Zhao ◽  
Zheng Li ◽  
Jia Xu ◽  
...  
Keyword(s):  
Hexavalent Chromium ◽  
Photoelectron Spectroscopy ◽  
Stenotrophomonas Maltophilia ◽  
Treatment Options ◽  
Trisodium Citrate ◽  
Aerobic Conditions ◽  
Bacterial Removal ◽  
Balance Analysis ◽  
C And N ◽  
High Concentrations

Environmental contextIndustrial development has caused the release of hexavalent chromium and nitrates into the environment. Interactions of hexavalent chromium and nitrates with microorganisms are important both for understanding environmental behaviour and for treatment options. Bacterial removal of both chromium and nitrate was optimised in waters relevant to waste streams and the environment. Abstract An isolated strain of the bacterium Stenotrophomonas maltophilia strain W26, is shown to be capable of the simultaneous removal of nitrate and CrVI under aerobic conditions. Notably, 10mg L−1 of CrVI and 500mg L−1 of nitrate were reduced by 92.6% and 85.2%, respectively, by strain W26. Results showed that an excellent denitrification efficiency of 96.0% could be reached at the optimal conditions of a C/N ratio of 10, using a carbon source of trisodium citrate, at pH 7.5, and a nitrate concentration of 500mg L−1. Strain W26 could also effectively remove high concentrations of CrVI (50mg L−1, 93.2%) and nitrate (700mg L−1, 97.4%). By using the N balance analysis, energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS), the denitrification and CrVI transformation processes were verified. CrVI, immobilised on the cell surface by W26, was reduced to CrIII, through interaction with of O=C and N-H groups. This study indicates that the isolated strain W26 has the potential to treat wastewater containing combined nitrate and CrVI contamination.

scholarly journals Removal of hexavalent chromium from wastewater by Cu/Fe bimetallic nanoparticles

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jien Ye ◽  
Yi Wang ◽  
Qiao Xu ◽  
Hanxin Wu ◽  
Jianhao Tong ◽  
...  
Keyword(s):  
Hexavalent Chromium ◽  
Removal Efficiency ◽  
Photoelectron Spectroscopy ◽  
Bimetallic Nanoparticles ◽  
Chemical Reduction ◽  
Particle Surface ◽  
Zerovalent Iron ◽  
Order Model ◽  
X Ray ◽  
Nanoscale Zerovalent Iron

AbstractPassivation of nanoscale zerovalent iron hinders its efficiency in water treatment, and loading another catalytic metal has been found to improve the efficiency significantly. In this study, Cu/Fe bimetallic nanoparticles were prepared by liquid-phase chemical reduction for removal of hexavalent chromium (Cr(VI)) from wastewater. Synthesized bimetallic nanoparticles were characterized by transmission electron microscopy, Brunauer–Emmet–Teller isotherm, and X-ray diffraction. The results showed that Cu loading can significantly enhance the removal efficiency of Cr(VI) by 29.3% to 84.0%, and the optimal Cu loading rate was 3% (wt%). The removal efficiency decreased with increasing initial pH and Cr(VI) concentration. The removal of Cr(VI) was better fitted by pseudo-second-order model than pseudo-first-order model. Thermodynamic analysis revealed that the Cr(VI) removal was spontaneous and endothermic, and the increase of reaction temperature facilitated the process. X-ray photoelectron spectroscopy (XPS) analysis indicated that Cr(VI) was completely reduced to Cr(III) and precipitated on the particle surface as hydroxylated Cr(OH)3 and CrxFe1−x(OH)3 coprecipitation. Our work could be beneficial for the application of iron-based nanomaterials in remediation of wastewater.

scholarly journals Synthesis of Exosome-Based Fluorescent Gold Nanoclusters for Cellular Imaging Applications

2021 ◽  
Vol 22 (9) ◽  
pp. 4433
Author(s):  
Eun Sung Lee ◽  
Byung Seok Cha ◽  
Seokjoon Kim ◽  
Ki Soo Park
Keyword(s):  
Photoelectron Spectroscopy ◽  
Low Cost ◽  
Stokes Shift ◽  
Gold Nanoclusters ◽  
Human Colon ◽  
Cellular Imaging ◽  
Metal Nanoclusters ◽  
Human Colon Cancer ◽  
X Ray ◽  
High Concentrations

In recent years, fluorescent metal nanoclusters have been used to develop bioimaging and sensing technology. Notably, protein-templated fluorescent gold nanoclusters (AuNCs) are attracting interest due to their excellent fluorescence properties and biocompatibility. Herein, we used an exosome template to synthesize AuNCs in an eco-friendly manner that required neither harsh conditions nor toxic chemicals. Specifically, we used a neutral (pH 7) and alkaline (pH 11.5) pH to synthesize two different exosome-based AuNCs (exo-AuNCs) with independent blue and red emission. Using field-emission scanning electron microscopy, energy dispersive X-ray microanalysis, nanoparticle tracking analysis, and X-ray photoelectron spectroscopy, we demonstrated that AuNCs were successfully formed in the exosomes. Red-emitting exo-AuNCs were found to have a larger Stokes shift and a stronger fluorescence intensity than the blue-emitting exo-AuNCs. Both exo-AuNCs were compatible with MCF-7 (human breast cancer), HeLa (human cervical cancer), and HT29 (human colon cancer) cells, although blue-emitting exo-AuNCs were cytotoxic at high concentrations (≥5 mg/mL). Red-emitting exo-AuNCs successfully stained the nucleus and were compatible with membrane-staining dyes. This is the first study to use exosomes to synthesize fluorescent nanomaterials for cellular imaging applications. As exosomes are naturally produced via secretion from almost all types of cell, the proposed method could serve as a strategy for low-cost production of versatile nanomaterials.

X-Ray-Induced Photoelectron Spectroscopy of Dentin as a Function of Duration of Ar +-Ion Etching

1997 ◽  
Vol 11 (4) ◽  
pp. 395-402
Author(s):  
J.J. Ten Bosch ◽  
J. De Vries ◽  
M.H. Van Der Veen
Keyword(s):  
Photoelectron Spectroscopy ◽  
Etching Time ◽  
Ion Etching ◽  
Final Level ◽  
Gold Sample ◽  
Gas Removal ◽  
Root Dentin ◽  
Dentin Matrix ◽  
C And N ◽  
True Values

XPS, or ESCA, measures the atomic concentration in the outermost layers of the sample. The surface is often etched with Ar+-ions before any measurement. We investigated the role thereof on XPS measurements of root dentin. Nine slices were cut from premolars. Slices were ground or broken. XPS was measured before etching. Six samples were then subjected to Ar+-ion etching (10 kV ions, 0.25 μA/mm2). A gold sample was also included. Relative concentrations of N and C decreased with etching time, while 0, P, and Ca increased. N and C curves were analyzed assuming a sum of two exponential decays and a final level. On average, τ1 = 20 sec for C and 17 sec for N. On average, τ2 = 278 sec for C and 350 sec for N. No differences between differently prepared samples were apparent. The gold sample showed a single decay to noise for C and N, with τ1 = 8 and 7 sec, respectively. We conclude that two decay processes are present, due to gas removal and to the removal of organic material from the dentin matrix, respectively. Thus, true values can be obtained by extrapolation to t = 0 of only the data obtained by summing the slow decay and the final level.

Preliminary Study on the Removal of Hexavalent Chromium in Wastewater with Reduction of Sulfur Dioxide

2013 ◽  
Vol 864-867 ◽  
pp. 1699-1703
Author(s):  
Ji Ming Wu ◽  
Sheng Gao Cheng
Keyword(s):  
Reaction Time ◽  
Sulfur Dioxide ◽  
Hexavalent Chromium ◽  
Reduction Reaction ◽  
High Concentration ◽  
Reaction Conditions ◽  
Ph Values ◽  
Different Temperatures ◽  
Preliminary Study ◽  
High Concentrations

The paper focused on a self-developed methodology through using sulfur dioxide to deal with high concentration of chromium-containing wastewater. It studied the effects of different pH values, different reaction time, different temperatures and different amounts of sulfur with sulfur dioxide reduction reaction on the chromium-containing wastewater. The results showed that: when the reaction conditions were controlled as follows: the pH values ranged from 2 to 4, the reaction temperature was controlled 40~60°C, the amount of sulfur in theoretical was 1.2 times and the reaction time was 40 min, the hexavalent chromium in the high concentrations of chromium-containing wastewater could be effectively removed.

scholarly journals Tribological properties of boron carbonitride coatings sliding against different wood (acerbic, beech, and lauan) balls

2019 ◽  
Vol 28 ◽  
pp. 096369351987573 ◽  
Author(s):  
Zhiwei Wu ◽  
Sihao Li ◽  
Zhaojun Xu ◽  
Qianzhi Wang ◽  
Fei Zhou
Keyword(s):  
Bias Voltage ◽  
Tribological Properties ◽  
Photoelectron Spectroscopy ◽  
Rf Magnetron Sputtering ◽  
Substrate Bias ◽  
Boron Carbonitride ◽  
Friction Behavior ◽  
Substrate Bias Voltage ◽  
Mechanical And Tribological Properties ◽  
C And N

Boron carbonitride (BCN) coatings were prepared using radio frequency (RF) magnetron sputtering via adjusting substrate bias voltage from −50 V to −200 V. The mechanical and tribological properties of the coatings were investigated. The coexistence of B–N, B–C, and N–C bonds was detected in coatings according to X-ray photoelectron spectroscopy analysis, indicating the formation of ternary BCN hybridization. The hardness of BCN coatings increased from 14.4 GPa to 24.3 GPa with an increase of substrate bias voltage, while their adhesion strength on substrate decreased. The friction behavior of BCN coatings sliding against different wood (acerbic, beech, and lauan) balls was examined using a ball-on-disk tribometer. The average friction coefficient fluctuated in a range of 0.74–1.02. The wear track of BCN coating sliding against hardwood (acerbic) presented obvious scratches, which were not noted as sliding against other softwood balls in comparison.

Effects of O3 and H2O oxidants on C and N-related impurities in atomic-layer-deposited La2O3 films observed by in situ x-ray photoelectron spectroscopy

2010 ◽  
Vol 97 (9) ◽  
pp. 092904 ◽  
Author(s):  
Tae Joo Park ◽  
Prasanna Sivasubramani ◽  
Brian E. Coss ◽  
Hyun-Chul Kim ◽  
Bongki Lee ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Atomic Layer ◽  
X Ray ◽  
Related Impurities ◽  
C And N

Low Pressure CVD Growth of AlxTi1-xN Films with Tetrakis- (Dimethylamido)Titanium (Tdmat) and Dimethyl Aluminum Hydride (DMAH) Precursors

1997 ◽  
Vol 495 ◽  
Author(s):  
Y.-M. Sun ◽  
J. Endle ◽  
J. G. Ekerdt ◽  
N. M. Russell ◽  
M. D. Healy ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Film Growth ◽  
Aluminum Hydride ◽  
Chemical Vapor ◽  
Initial Growth ◽  
Lower Growth ◽  
Al Content ◽  
Partial Pressures ◽  
Cvd Growth ◽  
C And N

ABSTRACTAlxTi1-xN film growth has been studied by a organometallic chemical vapor deposition and in-situ X-ray photoelectron spectroscopy. Terakis(dimethylamido)titanium (TDMAT) and dimethyl aluminum hydride (DMAH) were used as the Ti, N and Al precursors. AlTiN film growth was observed on SiO2/Si(100) with substrate temperatures between 200 and 400 °C. The Al content in the film is controlled by the ratio of partial pressures of the two precursors in the gas phase. The metal to C to N ratio is approximately constant at 1:1:1 for most conditions studied. The chemical states of Ti, C, and N in AlxTi1-xN and titanium-carbo-nitride (TiCN) films are identical, while the Al chemical state is nitride at low, but increasingly carbidic at high Al concentration. The initial growth rate on SiO2 was significantly suppressed by the presence of DMAH. At lower growth temperatures, the DMAH effect is more severe. Good step coverage was observed for AlxTi1-xN on 0.3 μm vias with a 3:1 aspect ratio.

scholarly journals Diphenyl Furans and Aza Analogs: Effects of Structural Modification on In Vitro Activity, DNA Binding, and Accumulation and Distribution in Trypanosomes

2007 ◽  
Vol 51 (8) ◽  
pp. 2801-2810 ◽  
Author(s):  
Amanda M. Mathis ◽  
Arlene S. Bridges ◽  
Mohamed A. Ismail ◽  
Arvind Kumar ◽  
Iris Francesconi ◽  
...  
Keyword(s):  
Mechanism Of Action ◽  
Structural Modification ◽  
Human African Trypanosomiasis ◽  
Treatment Options ◽  
Vitro Activity ◽  
In Vitro Activity ◽  
Antitrypanosomal Activity ◽  
Specific Accumulation ◽  
High Concentrations

ABSTRACT Human African trypanosomiasis is a devastating disease with only a few treatment options, including pentamidine. Diamidine compounds such as pentamidine, DB75, and DB820 are potent antitrypanosomal compounds. Previous investigations have shown that diamidines accumulate to high concentrations in trypanosomes. However, the mechanism of action of this class of compounds remains unknown. A long-hypothesized mechanism of action has been binding to DNA and interference with DNA-associated enzymes. The fluorescent diamidines, DB75 and DB820, have been shown to localize not only in the DNA-containing nucleus and kinetoplast of trypanosomes but also to the acidocalcisomes. Here we investigate two series of analogs of DB75 and DB820 with various levels of in vitro antitrypanosomal activity to determine whether any correlation exists between trypanosome accumulation, distribution, and in vitro activity. Despite wide ranges of in vitro antitrypanosomal activity, all of the compounds investigated accumulated to millimolar concentrations in trypanosomes over a period of 8 h. Interestingly, some of the less potent compounds accumulated to concentrations much higher than those of more potent compounds. All of the compounds were localized to the DNA-containing nucleus and/or kinetoplast, and many were also found in the acidocalcisomes. Accumulation in the nucleus and kinetoplast should be important to the mechanism of action of these compounds. The acidocalcisomes may also play a role in the mechanism of action of these compounds. This investigation suggests that the extent of accumulation alone is not responsible for killing trypanosomes and that organelle-specific accumulation may not predict in vitro activity.

Synthesis of Boron Carbonitride Films by Plasma-Based Ion Implantation

2007 ◽  
Vol 353-358 ◽  
pp. 1850-1853 ◽  
Author(s):  
Shu Yan Xu ◽  
Xin Xin Ma ◽  
Ming Ren Sun
Keyword(s):  
Ion Implantation ◽  
Photoelectron Spectroscopy ◽  
Nitrogen Plasma ◽  
Boron Carbonitride ◽  
X Ray ◽  
Unbalanced Magnetron Sputtering ◽  
Unbalanced Magnetron ◽  
Disorder Degree ◽  
Chemical States ◽  
C And N

BCN films were prepared with unbalanced magnetron sputtering boron carbide film followed by nitrogen plasma-based ion implantation at different voltages on Si substrate. The implantation voltages vary from 10 kV to 50 kV. The chemical states of B, C and N of the films were studied with X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The nano-hardness and elastic modulus of films were measured by Nano-Indenter. The results showed that amorphous BCN films formed in the nitrogen implanted layer. The amorphous peak becomes obvious with increasing of the implanted voltage when the voltage is under of 40 kV. The Nano-Indenter measurement showed that the B-C bond content and the disorder degree affect the hardness and modulus.

The antioxidants dimethylsulfoxide and dimethylthiourea affect the immediate adhesion responses of larval haemocytes from 3 lepidopteran insect species

2007 ◽  
Vol 53 (12) ◽  
pp. 1330-1347 ◽  
Author(s):  
Gary B. Dunphy ◽  
Genhui Chen ◽  
John M. Webster
Keyword(s):  
Galleria Mellonella ◽  
Granular Cell ◽  
Lepidopteran Insect ◽  
Bacterial Removal ◽  
Lepidopteran Insects ◽  
High Concentrations ◽  
Foreign Materials ◽  
Humoral Responses

Antioxidants, dimethylsulfoxide (DMSO) and dimethylthiourea (DMTU), at concentrations not affecting the viability of blood cells (haemocytes) from the larval stage of 3 lepidopteran insects — Galleria mellonella , Lymantria dispar , and Malacosoma disstria — differed in their influence on the innate binding of haemocytes to glass, bacteria to haemocytes, and on humoral responses to alien materials. In vitro DMSO had little effect, whereas DMTU substantially impaired the adhesion of the haemocyte types, the plasmatocytes and granular cells, to slides as well as the attachment of Bacillus subtilis to these haemocytes. Although both antioxidants increased lysozyme and phenoloxidase activities, there was no correlation of enzyme activity and haemocyte adhesion responses, possibly reflecting sequestered radicals. Nitric oxide and hydroxyl radicals offset the DMTU effect. In the absence of antioxidants, inactivate protein kinases A (PKA) and C (PKC) enhanced haemocyte aggregation. In general, DMSO, as opposed to DMTU, did not alter the effects of PKA and PKC activators and inhibitors on haemocyte aggregation or of PKC and PKA activities. High concentrations of DMSO and all levels of DMTU, although inhibiting PKA and PKC, inhibited haemocyte adhesion to slides. Comparable results occurred for DMTU-treated haemocytes incubated with B. subtilis. In vivo DMSO, unlike DMTU, did not impair plasmatocyte or granular cell responses to foreign materials, including bacterial removal from the haemolymph and nodulation.

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