JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
·
2022
·
IF 5.141
Liangchen Long,Yang Yang,Shijie You,Liangliang Wei,Baiyang Chen
Quantifying ultraviolet (UV) photon flux is important for water photolysis practice. However, it is currently challenging to quantify the photon flux of 185 nm vacuum UV (VUV 185 ) emitted by low-pressure mercury lamp (LPML) because of the interference of coexisting 254 nm UV (UV 254 ). Given that formaldehyde (FA) is insensitive to UV 254 within the time scale of interests whereas vulnerable to VUV 185 , this study for the first time evaluated the possibility of using FA as a chemical actinometer to determine the VUV 185 photon flux under varying conditions. Experimental results revealed that the photodegradation of FA followed a pseudo -1 st -order reaction kinetic under VUV 185 irradiation, and the products of initial concentration ( C 0 ) and reaction rate constants (i.e., C 0 × k ) were proportional to the numbers of LPMLs (under C 0 of 50–300 mg/L), suggesting that C 0 × k is an excellent indicator for photon flux determination. Increasing dissolved oxygen concentration from 1.0 to 7.8 mg/L, pH from 4.0 to 10.4, and temperature from 22 to 44 °C all imposed negligible interferences (variation ≤ 10%) on the C 0 × k values, proving that FA is a good actinometer for VUV 185 photon flux detection. Because FA can be measured readily by spectrophotometry method, its use as an actinometer is more convenient than conventional actinometers. Therefore, this study demonstrates that FA is a promising candidate of actinometer for VUV 185 quantification in the copresence of UV 254 .
研究领域:
环境科学
·
水处理工程
✓ 已验证
产品关联
DOI
高影响因子
ENVIRONMENTAL RESEARCH
·
2021
·
IF 6.498
Juan Li,Qi Zhang,Baiyang Chen,Lei Wang,Rongshu Zhu,Jie Yang
Understanding the formation and transformation of radicals generated by a low pressure mercury lamp emitting both 254 nm ultraviolet (UV 254 ) and 185 nm vacuum UV (VUV 185 ) is currently challenging due to the complexity of concurrent redox reactions occurring in this complex system. Because hydrogen peroxide (H 2 O 2 ) is a common product of both oxidizing and reducing radicals generated during the VUV irradiation process, monitoring the variations in H 2 O 2 levels can help us better understand the presence and relative dominance of different radicals. In this study, we systematically evaluated the effects of several selected anions on the formation of H 2 O 2 under a variety of pH and dissolved oxygen (DO) conditions. Results show that although addition of these anions inhibited the formation of H 2 O 2 , their H 2 O 2 -inhibition mechanisms are markedly different. At low concentrations (≤1.0 mg/L), chloride reduced the generation of H 2 O 2 primarily by consuming hydroxyl radicals (•OH); however, in high concentrations (11.0 mg/L), its light-screening effect was dominant. In comparison, the presence of bromide (≤1.0 mg/L) inhibited H 2 O 2 formation mainly by reacting rapidly with both •OH and H 2 O 2 . Carbonate and phosphorous species exerted influence mainly by consuming •OH. Along with irradiation, increasing pH significantly decreased H 2 O 2 levels, confirming that H 2 O 2 was formed mainly by •OH. In contrast, raising DO did not raise H 2 O 2 maximum yields, confirming that reducing radicals like aqueous electrons (e - aq ) and hydrogen atoms (•H) are not the key precursors of H 2 O 2 in this process. Mathematically, the evolutions of H 2 O 2 can be reliably modeled (R 2 ≥ 0.80) using a kinetics model incorporating H 2 O 2 formation and decomposition kinetics. The results of this study may contribute to better understanding the use of VUV technology in water/wastewater treatment.
研究领域:
环境科学
·
水处理技术
✓ 已验证
DOI
PubMed
高影响因子
JOURNAL OF PHARMACEUTICAL SCIENCES
·
2023
·
IF 3.8
Ya Xu,Huiyang Li,Nan Sun,Bingmei Yao,Wenjin Dai,Jian Wang,Sujia Si,Shuo Liu,Liqun Jiang
Background High Altitude Pulmonary Edema (HAPE) seriously threatens the health of people at high altitudes. There are drug treatments for HAPE, and dry powder formulations (DPFs) represent a rapid and accessible delivery vehicle for these drugs. However, there are presently no reports on the inhalability of DPFs in low-pressure environments. Given the reduced atmospheric pressure typical at high altitudes, conventional DPFs might not be suitable for inhalation. Therefore, it is necessary to elucidate the deposition behaviors of dry powder in the respiratory tract at low pressure, as well as to improve their pulmonary deposition efficiency via adjustments to their formulation and design. Methods The effect of air pressure, inspiratory velocity, and particle properties (such as size, density, and aerodynamic diameter) on pulmonary deposition of DPFs was calculated by a computational fluid dynamics (CFD)-coupled discrete phase model. DPFs of various aerodynamic diameters were prepared by spray drying, and the inhalability of these DPFs in a low-pressure environment was evaluated in mice. Finally, a mouse model of HAPE was established, and the treatment of HAPE by nifedipine-loaded DPFs with small aerodynamic diameter was validated. Results CFD results showed that low pressure decreased the deposition of DPFs in the lungs. At 0.5 standard atmosphere, DPFs with aerodynamic diameter of ∼2.0 μm could not enter the lower respiratory tract; however, a decrease in the physical diameter, density, and, consequently, the aerodynamic diameter of the DPFs was able to enhance pulmonary deposition of these powders. To validate the CFD results, three kinds of dry powder with aerodynamic diameters of 0.66, 0.98, and 2.00 μm were prepared by spray drying. Powders with smaller aerodynamic diameter could be inhaled into the lungs of mice more effectively, and, consequently could ameliorate the progression of HAPE more effectively than conventional powders. These results were consistent with the CFD results. Conclusions Low atmospheric pressure can prevent the pulmonary deposition of DPFs at high altitudes. Compared with conventional DPFs, powders with smaller aerodynamic diameter can be effectively inhaled at these pressures and thus might be more suitable for the treatment the HAPE.
研究领域:
药剂学
·
呼吸病学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Inorganics
·
2024
·Vol. 12
·期 9
·250
·
IF 3.1
Ye Li,Huiqing Yue,Quanli Zhang,Dumin Yan,Ziyi Li,Zhiwei Liu,Yingshu Liu,Yongyan Wang,Shifeng Wang,Xiong Yang
In oxygen production on plateaus, pressure swing adsorption (PSA) oxygen production is currently the most commonly used oxygen production method. In plateau regions, low pressure leads to a decrease in adsorbent nitrogen–oxygen separation performance, which affects the performance of PSA oxygen production, so it is particularly important to enhance adsorbent nitrogen–oxygen separation performance. In this paper, Li-LSX (lithium low-silicon aluminum X zeolite molecular sieve) adsorbents were modified using the liquid phase ion exchange method, and five kinds of modified adsorbents were obtained, namely AgLi-LSX, CaLi-LSX, ZnLi-LSX, CuLi-LSX, and FeLi-LSX, respectively. The influences of different metal ions and modification time lengths on the adsorbent nitrogen adsorption and nitrogen–oxygen separation coefficients were analyzed. Through theoretical calculations, the nitrogen and oxygen adsorption and separation performances of the modified adsorbents at different altitudes and low adsorption pressures were investigated. It is shown that the nitrogen adsorption capacity of the AgLi-LSX-1 adsorbent obtained from the modification experiment reaches 27.92 mL/g, which is 3.24 mL/g higher than that of Li-LSX; the nitrogen–oxygen separation coefficients of S1 and S2 are 19.24 and 7.54 higher, respectively; and the nitrogen–oxygen separation coefficients of S4 are 20.85 and 7.54 higher than those of Li-LSX, respectively. With the increase in altitude from 50 m to 5000 m, the nitrogen–oxygen separation coefficient of the AgLi-LSX-1 adsorbent increased rapidly from 20.85 to 57, and its nitrogen–oxygen separation coefficient S4 exceeded that of the Li-LSX adsorbent to reach 47.61 at an altitude of 4000 m. Therefore, the modified adsorbent AgLi-LSX-1 in this paper can enhance the performance of the PSA oxygen process for oxygen production in plateau applications.
研究领域:
材料科学
·
环境科学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2023
·
IF 15.1
Yuxuan Zhou,Yueting Wang,Zehua Zhang,Fuwei Li,Jian Cheng,Yinghua Ye,Jianbing Xu,Ruiqi Shen
The application and optimization of nano-composite energetic materials in the extreme and particular environment have become a subject of wide concern. Additionally, the design and selection of metastable intermixed composites (MICs) films in low pressure environment is the key problem to explore its future application. Here, 90 wt% high loading Al/CuO nanothermite films were prepared by a simple 3D direct writing approach. Four films with different thicknesses (66, 128, 152, 182 μm) were designed and their combustion properties were tested respectively. The low pressure combustion results show that the self-sustained burning rate of the film (thicker than 66 μm) can be adjusted and controlled in various air pressure environments (101–60 kPa). The self-sustained burning rate of film is affected by both thickness (66–182 μm) and air pressure (101–60 kPa). The lower the air pressure, the lower the burning rate. The greater the thickness, the higher the burning rate. The 66 μm film self-sustainedly burns at atmospheric pressure and extinguishes when the pressure was significantly reduced. The self-sustained combustion rates of the 128 and 152 μm film decreases with decreasing pressure until the pressure drops to 75 and 60 kPa respectively. The 182 μm film keeps self-sustained combustion in a manner of deflagration which is almost unaffected by air pressure, even when the pressure drops to 10 kPa. Simultaneously, it is found that the ignition temperature of the film is almost not affected by pressure. In addition, it is verified that the film has performances of excellent hydrophobic and combustion through air–water interface. These can cope with complex environmental humidity.
研究领域:
材料科学
·
燃烧学
·
航空航天工程
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL PHYSICS
·
2019
·
IF 1.822
Sihong Zhang,Jianyu Wang,Yan Lu,Weiwei Hou,Kai Cao,Shouhui Guo,Zhendong Wang,Li Wang
Highly ordered arrays of WS 2 crystals are grown on the SiO 2 /Si substrate using Pt/Ti metal as seed materials by a low pressure chemical vapor deposition method. High magnification SEM images and Raman spectrum reveal that the WS 2 flakes are induced and grown around the Pt/Ti metal, and the diameter of a single unit is up to 100 μm, which have contribute to the direct construction of functional devices on the substrate. HRTEM measurements further confirm that the obtained flakes are the WS 2 crystal with good crystallinity. The results show that highly ordered arrays of WS 2 crystals will have potential applications in electronic and optoelectronic devices.
研究领域:
材料科学
·
纳米技术
✓ 已验证
DOI
高影响因子
TALANTA
·
2016
·
IF 4.035
Zhen Li,Ce Xu,Jinian Shu,Bo Yang,Yao Zou
Real-time detection of lung cancer-related volatile organic compounds (VOCs) is a promising, non-intrusive technique for lung cancer (LC) prescreening. In this study, a novel method was designed to enhance the detection selectivity and sensitivity of LC-related polar VOCs by dichloromethane (CH 2 Cl 2 ) doping-assisted low-pressure photoionization mass spectrometry (LPPI-MS). Compared with conventional LPPI-MS, CH 2 Cl 2 doping-assisted LPPI-MS boosted the peak intensities of n -propanol, n -pentanal, acetone, and butyl acetate in nitrogen specifically by 53, 18, 16, and 43 times, respectively. The signal intensities of their daughter ions were inhibited or reduced. At relative humidity (RH) of 20%, the sensitivities of n -propanol, n -pentanal, acetone, and butyl acetate detection ranged from 116 to 452 counts/ppbv with a detection time of 10 s and R 2 >0.99 for the linear calibration curves . The method was also applicable under higher RH levels of 50% and 90%. Breath samples obtained from 10 volunteers and spiked samples were investigated. Eight-fold enhancements in the signal intensities of polar VOCs were observed in the normal and spiked samples. These preliminary results demonstrate the efficacy of the dichloromethane doping-assisted LPPI technique for the detection of LC-related polar VOCs. Further studies are indispensible to illustrating the detailed mechanism and applying the technique to breath diagnosis.
研究领域:
医学
·
分析化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CEMENT & CONCRETE COMPOSITES
·
2022
·
IF 9.93
Zhenxing Du,Jianbo Xiong,Wenqiang Zuo,Wei She
Air bubble instability leads to the deterioration of air-void structure and threatens the frost resistance of air-entrained concrete, especially in plateau low atmospheric pressure environment. In this study, modified partially hydrophobic nano-silica (NS) particles are used to stabilize entrained air bubbles in cement mortar under low atmospheric pressure. The experimental results indicate that low atmospheric pressure has a limited effect on the bubble size distribution during the bubble generation process. However, the accelerated Ostwald ripening of the bubble system under low atmospheric pressure leads to a significant increase in the mean bubble size and air content loss. Furthermore, the modified NS shows a noticeable bubble stabilization effect. When adding 3% modified nano-silica (NS/MPS), the air-void structure of cement mortar does not show deterioration under 60 kPa. The analysis of bubble shells in foam, fresh and hardened paste system revealed that the NS/MPS with suitable wettability could strongly adsorb at the air-water interface and form adsorption layers around bubbles, thus reduce the gas permeability across the bubble films and prevent the Ostwald ripening of bubbles. This work finally provides a viable method to stabilize air bubbles and improve the air-void structure of concrete in some extreme environments.
研究领域:
材料科学
·
土木工程
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2016
·
IF 5.31
Jiangya Ma,Jun Shi,Houcheng Ding,Guocheng Zhu,Kun Fu,Xue Fu
This work presents a preparation process and flocculation performance evaluation of a novel cationic polyacrylamide PADC synthesized by low-pressure ultraviolet (UV) initiation. Flocculant of PADC was polymerized with acrylamide (AM), diallyl dimethyl ammonium chloride (DMDAAC) and coconut diethanolamide (CDEA) in homogeneous aqueous solution under the irradiation of low-pressure UV, and 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone (Irgacure2959) was used as photo sensitizer. The factors that affect polymerization were investigated; these include monomer concentration, initiator dosage, mass ratio of m AM : m DMDAAC and irradiation time. Structures and morphologies were characterized by Fourier transform-infrared (FTIR) spectroscopy, nuclear magnetic resonance hydrogen (1H NMR) spectra, scanning electron microscope (SEM), and thermo gravimetric and differential thermal analysis (TG-DTA). The flocculation performance was evaluated by removing high turbidity kaolin suspension; flocculation mechanism was also correspondingly analyzed. Experimental results show that the PADC efficiently removes the suspended particles efficiently by charge neutralization and bridging effect in an environment with wide range of pH.
研究领域:
环境科学
·
高分子化学
✓ 已验证
DOI
高影响因子
Molecular Medicine Reports
·
2019
·Vol. 19
·期 4
·2758-2766
·
IF 1.851
Ya Hou,Xiaobo Wang,Xiaorui Chen,Jing Zhang,Xiaopeng Ai,Yusheng Liang,Yangyang Yu,Yi Zhang,Xianli Meng,Tingting Kuang,Yao Hu
This study was conducted to establish a stable hypobaric hypoxia brain injury model. SD rats were randomly separated into control and model groups, and placed outside or inside of a hypobaric chamber, respectively. Subsequent to 24 h anoxic exposure, plasma superoxide dismutase (SOD), malondialdehyde (MDA), glutathione (GSH), oxidized glutathione (GSSG) and lactate dehydrogenase (LDH) were measured using commercial biochemical kits. Hematoxylin‑eosin (H&E), Nissl's and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining were used to observe the morphology of neurons in the hippocampus. The protein expression levels of apoptotic protease activating factor‑1 (Apaf‑1), hypoxia inducible factor‑1α (HIF‑1α), caspase‑3, cleaved caspase‑3, Bcl‑2‑associated X protein (Bax) and cytochrome c (cyto‑c) were detected using western blot and immunohistochemistry analyses. Hypoxic substantially induced morphological lesions in the hippocampus concomitant with the physical behavioral performance deficit. Furthermore, hypoxia markedly exacerbated the levels of MDA, LDH and GSSG, and restrained GSH (P<0.01) and SOD (P<0.05) levels compared with the control group. In addition, hypoxia significantly induced the protein expression of Apaf‑1, HIF‑1α, caspase‑3, cleaved caspase‑3, Bax and Cyto‑c (P<0.01) compared with the control group. Finally, a lower number and volume of Nissl bodies were verified in the hypoxic group. TUNEL results demonstrated a greater number of apoptotic cells in the hypoxic group. The present study demonstrates a model of rat hypoxic brain injuries induced by a hypobaric chamber at 9,000 m for 24 h. Furthermore, the redox enzyme, HIF‑1α and mitochondrial apoptosis‑associated protein, along with H&E and Nissl's staining, may be applied to evaluate the degree of injury.
研究领域:
神经科学
·
药理学
·
分子生物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Materials Today Communications
·
2023
·
IF 3.8
Jiafan Wang,Lihong Nie,Chenxiao Zhang,Beifu Wang
This paper reports the first surface modification of polyetherimide (PEI) ultrafiltration membranes using low-pressure air plasma-treated surfaces to induce acrylic acid (AA) graft polymerization, significantly improving their retention and fouling resistance properties. The successful formation of graft layers was verified by water contact angle (WCA) measurement of hydrophilic changes and Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis of the surface chemistry. Scanning electron microscopy (SEM) was used to analyze the morphological features, and atomic force microscopy (AFM) was tested for changes in surface roughness. The overall property changes after grafting were evaluated by mechanical tests and filtration tests. Methyl tert-butyl ether (MTBE) was chosen to measure the oil-water separability. The results showed that the membrane surface obtained PAA dense graft layer and improved hydrophilicity (CA from 57.62° to 29.26°) with no loss of tensile properties . In addition, the modified grafted membranes showed a high retention rate of BSA of 95.1 %, while the rejection rate of MTBE increased from 31.8 % to 75.9 %. Notably, PEI-g-AA fully recovered the permeability by simple water backwashing, exhibiting excellent antifouling performance. Therefore, this communication demonstrates that graft modification on the surface of PEI membranes is feasible and effective, and provides a new idea of PEI modification, which is valuable for exploring the development of high-efficiency ultrafiltration membranes.
研究领域:
材料科学
·
环境工程
✓ 已验证
产品关联
DOI
高影响因子
Frontiers in Pharmacology
·
2025
·
IF 4.8
Gang Zhao,Yajuan Li,Mengyuan Liu,Wei Chang,Hui Shen,Junhui Xue,Fengzhou Liu
Objective: This study investigates the effects of acute hypobaric hypoxia (HH) on the anti-fatigue properties of pitolisant and explores the underlying mechanisms. The aim is to provide a theoretical basis for expanding its clinical indications and optimizing its use in individuals exposed to HH conditions.Methods: The anti-fatigue effects of pitolisant were evaluated using the water maze, novel object recognition, and rotating rod tests. Drug concentrations and dopamine levels were analyzed using High-Performance Liquid Chromatography-Mass Spectrometry/Mass Spectrometry (HPLC-MS/MS). Additionally, gene and protein expression levels of P-glycoprotein (P-gp) and organic cation transporter 1 (OCT1) were assessed to explore the mechanisms by which HH affects pitolisant’s pharmacodynamics.Results: A 40 mg/kg dose of pitolisant significantly improved learning, memory, cognitive, and motor functions in sleep-deprived mice under HH conditions (P < 0.05). Pharmacokinetic analysis revealed a reduction in pitolisant concentration in the brain under HH conditions. Furthermore, OCT1 protein expression decreased after 1 h and 1 day of HH exposure (P < 0.05), while P-gp expression decreased after 1 h (P < 0.05).Conclusion: HH possibly reduced pitolisant’s brain concentration and efficacy by altering the expression of OCT1 and P-gp transporters. A 40 mg/kg dose was necessary for an effective anti-fatigue response. Pitolisant shows potential for supporting circadian rhythm regulation in shift workers and individuals suffering from jet lag. When used under HH conditions, adjusting the dose and frequency may be necessary due to altered pharmacokinetics.
研究领域:
药理学
·
神经科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）