Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 53
Filter
Add more filters

Country/Region as subject
Publication year range
1.
Nature ; 573(7775): 558-562, 2019 09.
Article in English | MEDLINE | ID: mdl-31554980

ABSTRACT

High-pressure transitions are thought to modify hydrogen molecules to a molecular metallic solid and finally to an atomic metal1, which is predicted to have exotic physical properties and the topology of a two-component (electron and proton) superconducting superfluid condensate2,3. Therefore, understanding such transitions remains an important objective in condensed matter physics4,5. However, measurements of the crystal structure of solid hydrogen, which provides crucial information about the metallization of hydrogen under compression, are lacking for most high-pressure phases, owing to the considerable technical challenges involved in X-ray and neutron diffraction measurements under extreme conditions. Here we present a single-crystal X-ray diffraction study of solid hydrogen at pressures of up to 254 gigapascals that reveals the crystallographic nature of the transitions from phase I to phases III and IV. Under compression, hydrogen molecules remain in the hexagonal close-packed (hcp) crystal lattice structure, accompanied by a monotonic increase in anisotropy. In addition, the pressure-dependent decrease of the unit cell volume exhibits a slope change when entering phase IV, suggesting a second-order isostructural phase transition. Our results indicate that the precursor to the exotic two-component atomic hydrogen may consist of electronic transitions caused by a highly distorted hcp Brillouin zone and molecular-symmetry breaking.


Subject(s)
Hydrogen/chemistry , Models, Molecular , Pressure , Electronics , Neutron Diffraction , Phase Transition , X-Ray Diffraction
2.
Environ Sci Technol ; 58(26): 11822-11832, 2024 Jul 02.
Article in English | MEDLINE | ID: mdl-38899941

ABSTRACT

The potential of Ru(III)-mediated advanced oxidation processes has attracted attention due to the recyclable catalysis, high efficiency at circumneutral pHs, and robust resistance against background anions (e.g., phosphate). However, the reactive species in Ru(III)-peracetic acid (PAA) and Ru(III)-ferrate(VI) (FeO42-) systems have not been rigorously examined and were tentatively attributed to organic radicals (CH3C(O)O•/CH3C(O)OO•) and Fe(IV)/Ru(V), representing single electron transfer (SET) and double electron transfer (DET) mechanisms, respectively. Herein, the reaction mechanisms of both systems were investigated by chemical probes, stoichiometry, and electrochemical analysis, revealing different reaction pathways. The negligible contribution of hydroxyl (HO•) and organic (CH3C(O)O•/CH3C(O)OO•) radicals in the Ru(III)-PAA system clearly indicated a DET reaction via oxygen atom transfer (OAT) that produces Ru(V) as the only reactive species. Further, the Ru(III)-performic acid (PFA) system exhibited a similar OAT oxidation mechanism and efficiency. In contrast, the 1:2 stoichiometry and negligible Fe(IV) formation suggested the SET reaction between Ru(III) and ferrate(VI), generating Ru(IV), Ru(V), and Fe(V) as reactive species for micropollutant abatement. Despite the slower oxidation rate constant (kinetically modeled), Ru(V) could contribute comparably as Fe(V) to oxidation due to its higher steady-state concentration. These reaction mechanisms are distinctly different from the previous studies and provide new mechanistic insights into Ru chemistry and Ru(III)-based AOPs.


Subject(s)
Oxidation-Reduction , Ruthenium , Ruthenium/chemistry , Electron Transport , Catalysis , Iron/chemistry
3.
Environ Sci Technol ; 57(47): 18898-18908, 2023 Nov 28.
Article in English | MEDLINE | ID: mdl-37489812

ABSTRACT

Peracetic acid (PAA) and performic acid (PFA) are two major peroxyacid (POA) oxidants of growing usage. This study reports the first systematic evaluation of PAA, PFA, and chlorine for their disinfection byproduct (DBP) formation potential in wastewater with or without high halide (i.e., bromide or iodide) concentrations. Compared with chlorine, DBP formation by PAA and PFA was minimal in regular wastewater. However, during 24 h disinfection of saline wastewater, PAA surprisingly produced more brominated and iodinated DBPs than chlorine, while PFA effectively kept all tested DBPs at bay. To understand these phenomena, a kinetic model was developed based on the literature and an additional kinetic investigation of POA decay and DBP (e.g., bromate, iodate, and iodophenol) generation in the POA/halide systems. The results show that PFA not only oxidizes halides 4-5 times faster than PAA to the corresponding HOBr or HOI but also efficiently oxidizes HOI/IO- to IO3-, thereby mitigating iodinated DBP formation. Additionally, PFA's rapid self-decay and slow release of H2O2 limit the HOBr level over the long-term oxidation in bromide-containing water. For saline water, this paper reveals the DBP formation potential of PAA and identifies PFA as an alternative to minimize DBPs. The new kinetic model is useful to optimize oxidant selection and elucidate involved DBP chemistry.


Subject(s)
Disinfectants , Water Pollutants, Chemical , Water Purification , Peracetic Acid , Disinfection/methods , Hydrogen Peroxide , Wastewater , Chlorine , Bromides , Oxidants , Chlorides , Halogenation , Water Purification/methods , Water Pollutants, Chemical/analysis
4.
Environ Sci Technol ; 57(47): 18929-18939, 2023 Nov 28.
Article in English | MEDLINE | ID: mdl-37224105

ABSTRACT

Metal-based advanced oxidation processes (AOPs) with peracetic acid (PAA) have been extensively studied to degrade micropollutants (MPs) in wastewater. Mn(II) is a commonly used homogeneous metal catalyst for oxidant activation, but it performs poorly with PAA. This study identifies that the biodegradable chelating ligand picolinic acid (PICA) can significantly mediate Mn(II) activation of PAA for accelerated MP degradation. Results show that, while Mn(II) alone has minimal reactivity toward PAA, the presence of PICA accelerates PAA loss by Mn(II). The PAA-Mn(II)-PICA system removes various MPs (methylene blue, bisphenol A, naproxen, sulfamethoxazole, carbamazepine, and trimethoprim) rapidly at neutral pH, achieving >60% removal within 10 min in clean and wastewater matrices. Coexistent H2O2 and acetic acid in PAA play a negligible role in rapid MP degradation. In-depth evaluation with scavengers and probe compounds (tert-butyl alcohol, methanol, methyl phenyl sulfoxide, and methyl phenyl sulfone) suggested that high-valent Mn species (Mn(V)) is a likely main reactive species leading to rapid MP degradation, whereas soluble Mn(III)-PICA and radicals (CH3C(O)O• and CH3C(O)OO•) are minor reactive species. This study broadens the mechanistic understanding of metal-based AOPs using PAA in combination with chelating agents and indicates the PAA-Mn(II)-PICA system as a novel AOP for wastewater treatment.


Subject(s)
Peracetic Acid , Water Pollutants, Chemical , Hydrogen Peroxide , Wastewater , Oxidation-Reduction
5.
Environ Sci Technol ; 57(47): 19033-19042, 2023 Nov 28.
Article in English | MEDLINE | ID: mdl-37384585

ABSTRACT

The increasing presence of antibiotics in water sources threatens public health and ecosystems. Various treatments have been previously applied to degrade antibiotics, yet their efficiency is commonly hindered by the presence of natural organic matter (NOM) in water. On the contrary, we show here that nine types of NOM and NOM model compounds improved the removal of trimethoprim and sulfamethoxazole by ferrate(VI) (FeVIO42-, Fe(VI)) under mild alkaline conditions. This is probably associated with the presence of phenolic moieties in NOMs, as suggested by first-order kinetics using NOM, phenol, and hydroquinone. Electron paramagnetic resonance reveals that NOM radicals are generated within milliseconds in the Fe(VI)-NOM system via single-electron transfer from NOM to Fe(VI) with the formation of Fe(V). The dominance of the Fe(V) reaction with antibiotics resulted in their enhanced removal despite concurrent reactions between Fe(V) and NOM moieties, the radicals, and water. Kinetic modeling considering Fe(V) explains the enhanced kinetics of antibiotics abatement at low phenol concentrations. Experiments with humic and fulvic acids of lake and river waters show similar results, thus supporting the enhanced abatement of antibiotics in real water situations.


Subject(s)
Water Pollutants, Chemical , Water Purification , Anti-Bacterial Agents , Ecosystem , Water Pollutants, Chemical/analysis , Oxidation-Reduction , Phenols , Water , Phenol , Water Purification/methods , Kinetics
6.
Environ Sci Technol ; 57(47): 18710-18721, 2023 Nov 28.
Article in English | MEDLINE | ID: mdl-36995048

ABSTRACT

Peroxyacids (POAs) are a promising alternative to chlorine for reducing the formation of disinfection byproducts. However, their capacity for microbial inactivation and mechanisms of action require further investigation. We evaluated the efficacy of three POAs (performic acid (PFA), peracetic acid (PAA), and perpropionic acid (PPA)) and chlor(am)ine for inactivation of four representative microorganisms (Escherichia coli (Gram-negative bacteria), Staphylococcus epidermidis (Gram-positive bacteria), MS2 bacteriophage (nonenveloped virus), and Φ6 (enveloped virus)) and for reaction rates with biomolecules (amino acids and nucleotides). Bacterial inactivation efficacy (in anaerobic membrane bioreactor (AnMBR) effluent) followed the order of PFA > chlorine > PAA ≈ PPA. Fluorescence microscopic analysis indicated that free chlorine induced surface damage and cell lysis rapidly, whereas POAs led to intracellular oxidative stress through penetrating the intact cell membrane. However, POAs (50 µM) were less effective than chlorine at inactivating viruses, achieving only ∼1-log PFU removal for MS2 and Φ6 after 30 min of reaction in phosphate buffer without genome damage. Results suggest that POAs' unique interaction with bacteria and ineffective viral inactivation could be attributed to their selectivity toward cysteine and methionine through oxygen-transfer reactions and limited reactivity for other biomolecules. These mechanistic insights could inform the application of POAs in water and wastewater treatment.


Subject(s)
Disinfectants , Water Purification , Disinfectants/pharmacology , Virus Inactivation , Chlorine/pharmacology , Peracetic Acid/pharmacology , Disinfection/methods , Bacteria
7.
J Phys Chem A ; 127(10): 2314-2321, 2023 Mar 16.
Article in English | MEDLINE | ID: mdl-36862970

ABSTRACT

The occurrence of micropollutants in water threatens public health and ecology. Removal of micropollutants such as pharmaceuticals by a green oxidant, ferrate(VI) (FeVIO42-, Fe(VI)) can be accomplished. However, electron-deficient pharmaceuticals, such as carbamazepine (CBZ) showed a low removal rate by Fe(VI). This work investigates the activation of Fe(VI) by adding nine amino acids (AA) of different functionalities to accelerate the removal of CBZ in water under mild alkaline conditions. Among the studied amino acids, proline, a cyclic AA, had the highest removal of CBZ. The accelerated effect of proline was ascribed by demonstrating the involvement of highly reactive intermediate Fe(V) species, generated by one-electron transfer by the reaction of Fe(VI) with proline (i.e., Fe(VI) + proline → Fe(V) + proline•). The degradation kinetics of CBZ by a Fe(VI)-proline system was interpreted by kinetic modeling of the reactions involved that estimated the rate of the reaction of Fe(V) with CBZ as (1.03 ± 0.21) × 106 M-1 s-1, which was several orders of magnitude greater than that of Fe(VI) of 2.25 M-1 s-1. Overall, natural compounds such as amino acids may be applied to increase the removal efficiency of recalcitrant micropollutants by Fe(VI).


Subject(s)
Amino Acids , Water Pollutants, Chemical , Proline , Water Pollutants, Chemical/chemistry , Oxidation-Reduction , Kinetics , Pharmaceutical Preparations
8.
Environ Sci Technol ; 56(16): 11683-11693, 2022 08 16.
Article in English | MEDLINE | ID: mdl-35880779

ABSTRACT

Ferrate(VI) and peracetic acid (PAA) are two oxidants of growing importance in water treatment. Recently, our group found that simultaneous application of ferrate(VI) and PAA led to much faster degradation of micropollutants compared to that by a single oxidant, and this paper systematically evaluated the underlying mechanisms. First, we used benzoic acid and methyl phenyl sulfoxide as probe compounds and concluded that Fe(IV)/Fe(V) was the main reactive species, while organic radicals [CH3C(O)O•/CH3C(O)OO•] had negligible contribution. Second, we removed the coexistent hydrogen peroxide (H2O2) in PAA stock solution with free chlorine and, to our surprise, found the second-order reaction rate constant between ferrate(VI) and PAA to be only about 1.44 ± 0.12 M-1s-1 while that of H2O2 was as high as (2.01 ± 0.12) × 101 M-1s-1 at pH 9.0. Finally, further experiments on ferrate(VI)-bisulfite and ferrate(VI)-2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic)acid systems confirmed that PAA was not an activator for ferrate(VI). Rather, PAA could enhance the oxidation capacity of Fe(IV)/Fe(V), making their oxidation outcompete self-decay. This study, for the first time, reveals the ability of PAA to promote electron transfer efficiency between high-valent metals and organic contaminants and confirms the benefits of co-application of ferrate(VI) and PAA for alkaline wastewater treatment.


Subject(s)
Water Pollutants, Chemical , Water Purification , Electrons , Hydrogen Peroxide , Iron , Oxidants/chemistry , Oxidation-Reduction , Peracetic Acid , Water Pollutants, Chemical/chemistry
9.
Environ Sci Technol ; 56(7): 4437-4446, 2022 04 05.
Article in English | MEDLINE | ID: mdl-35319885

ABSTRACT

Activation of peracetic acid (PAA) with iron species is an emerging advanced oxidation process (AOP). This study investigates the use of the chelating agent picolinic acid (PICA) to extend the pH range and enhance the performance of the PAA-Fe(III) AOP. Compared to the PAA-Fe(III) system, the PAA-Fe(III)-PICA system degrades various micropollutants (MPs: methylene blue, naproxen, sulfamethoxazole, carbamazepine, trimethoprim, diclofenac, and bisphenol-A) much more rapidly at higher pH, achieving almost complete removal of parent compounds within 10 min. PAA significantly outperforms the coexistent H2O2 and is the key oxidant for rapid compound degradation. Other chelating agents, EDTA, NTA, citric acid, proline, and nicotinic acid, could not enhance MP degradation in the PAA-Fe(III) system, while 2,6-pyridinedicarboxylic acid with a structure similar to PICA moderately enhanced MP degradation. Experiments with scavengers (tert-butyl alcohol and methyl phenyl sulfoxide) and a probe compound (benzoic acid) confirmed that high-valent iron species [Fe(IV) and/or Fe(V)], rather than radicals, are the major reactive species contributing to MP degradation. The oxidation products of methylene blue, naproxen, and sulfamethoxazole by PAA-Fe(III)-PICA were characterized and supported the proposed mechanism. This work demonstrates that PICA is an effective complexing ligand to assist the Fenton reaction of PAA by extending the applicable pH range and accelerating the catalytic ability of Fe(III).


Subject(s)
Peracetic Acid , Water Pollutants, Chemical , Ferric Compounds , Hydrogen Peroxide , Oxidation-Reduction , Picolinic Acids
10.
Phys Rev Lett ; 126(3): 036402, 2021 Jan 22.
Article in English | MEDLINE | ID: mdl-33543962

ABSTRACT

Metallization of hydrogen as a key problem in modern physics is the pressure-induced evolution of the hydrogen electronic band from a wide-gap insulator to a closed gap metal. However, due to its remarkably high energy, the electronic band gap of insulating hydrogen has never before been directly observed under pressure. Using high-brilliance, high-energy synchrotron radiation, we developed an inelastic x-ray probe to yield the hydrogen electronic band information in situ under high pressures in a diamond-anvil cell. The dynamic structure factor of hydrogen was measured over a large energy range of 45 eV. The electronic band gap was found to decrease linearly from 10.9 to 6.57 eV, with an 8.6 times densification (ρ/ρ_{0}∼8.6) from zero pressure up to 90 GPa.

11.
Proc Natl Acad Sci U S A ; 115(8): 1713-1717, 2018 02 20.
Article in English | MEDLINE | ID: mdl-29432145

ABSTRACT

The diamond anvil cell (DAC) is considered one of the dominant devices to generate ultrahigh static pressure. The development of the DAC technique has enabled researchers to explore rich high-pressure science in the multimegabar pressure range. Here, we investigated the behavior of the DAC up to 400 GPa, which is the accepted pressure limit of a conventional DAC. By using a submicrometer synchrotron X-ray beam, double cuppings of the beveled diamond anvils were observed experimentally. Details of pressure loading, distribution, gasket-thickness variation, and diamond anvil deformation were studied to understand the generation of ultrahigh pressures, which may improve the conventional DAC techniques.

12.
J Infect Dis ; 221(5): 820-829, 2020 02 18.
Article in English | MEDLINE | ID: mdl-31630185

ABSTRACT

The human intestinal pathogen enterohemorrhagic Escherichia coli (EHEC) O157:H7 causes bloody diarrhea, hemorrhagic colitis, and fatal hemolytic uremic syndrome. Its genome contains 177 unique O islands (OIs), which contribute largely to the high virulence and pathogenicity although most OI genes remain uncharacterized. In the current study, we demonstrated that OI-19 is required for EHEC O157:H7 adherence to host cells. Z0442 (OI-encoded virulence regulator A [OvrA]) encoded in OI-19 positively regulated bacterial adherence by activating locus of enterocyte effacement (LEE) gene expression through direct OvrA binding to the gene promoter region of the LEE gene master regulator Ler. Mouse colonization experiments revealed that OvrA promotes EHEC O157:H7 adherence in mouse intestine, preferentially the colon. Finally, OvrA also regulated virulence in other non-O157 pathogenic E. coli, including EHEC strains O145:H28 and O157:H16 and enteropathogenic E. coli strain O55:H7. Our work markedly enriches the understanding of bacterial adherence control and provides another example of laterally acquired regulators that mediate LEE gene expression.


Subject(s)
Escherichia coli Infections/microbiology , Escherichia coli O157/genetics , Escherichia coli O157/pathogenicity , Escherichia coli Proteins/genetics , Gene Expression Regulation, Bacterial , Gene Expression , Trans-Activators/genetics , Animals , Bacterial Adhesion/genetics , Disease Models, Animal , Escherichia coli Proteins/metabolism , Female , Mice , Mice, Inbred BALB C , Phosphoproteins/genetics , Promoter Regions, Genetic/genetics , Trans-Activators/metabolism , Virulence/genetics
13.
Proc Natl Acad Sci U S A ; 114(14): 3596-3600, 2017 04 04.
Article in English | MEDLINE | ID: mdl-28289218

ABSTRACT

"Chemical precompression" through introducing impurity atoms into hydrogen has been proposed as a method to facilitate metallization of hydrogen under external pressure. Here we selected Ar(H2)2, a hydrogen-rich compound with molecular hydrogen, to explore the effect of "doping" on the intermolecular interaction of H2 molecules and metallization at ultrahigh pressure. Ar(H2)2 was studied experimentally by synchrotron X-ray diffraction to 265 GPa, by Raman and optical absorption spectroscopy to 358 GPa, and theoretically using the density-functional theory. Our measurements of the optical bandgap and the vibron frequency show that Ar(H2)2 retains 2-eV bandgap and H2 molecular units up to 358 GPa. This is attributed to reduced intermolecular interactions between H2 molecules in Ar(H2)2 compared with that in solid H2 A splitting of the molecular vibron mode above 216 GPa suggests an orientational ordering transition, which is not accompanied by a change in lattice symmetry. The experimental and theoretical equations of state of Ar(H2)2 provide direct insight into the structure and bonding of this hydrogen-rich system, suggesting a negative chemical pressure on H2 molecules brought about by doping of Ar.

14.
Biochem Biophys Res Commun ; 517(3): 427-432, 2019 09 24.
Article in English | MEDLINE | ID: mdl-31376937

ABSTRACT

Citrobacter species are opportunistic bacterial pathogens that are implicated in both nosocomial and community-acquired infections. Among the Citrobacter species, Citrobacter koseri is often isolated from clinical material, and it can cause meningitis and brain abscesses in neonates and immunocompromised individuals, thus posing a great threat to human health. However, the virulence determinants of C. koseri remain largely unknown. Myo-inositol is an abundant carbohydrate in the environment and in certain organs of the human body, especially the brain. The C. koseri genome harbors a cluster of genes, QCQ70420.1 to QCQ70429.1 (named the Ino-cluster in this study), which encode IolBCDE, MmsA, and an ATP-binding cassette transporter. The gene cluster may be involved in the utilization of myo-inositol. To investigate the functions of the Ino-cluster in C. koseri, we constructed a mutant strain by deleting the Ino-cluster and found that the mutant could not use myo-inositol as the sole carbon source, confirming that this cluster is responsible for myo-inositol utilization. Moreover, we investigated the function of the Ino-cluster and myo-inositol utilization in C. koseri pathogenicity. Deletion of the Ino-cluster significantly impaired C. koseri colonization of the brain of infected Sprague-Dawley (SD) rats and BALB/c mice, and this increased the survival rate of the infected animals, indicating that the Ino-cluster and the ability to use myo-inositol are essential for C. koseri pathogenicity. Taken together, our findings suggest that using the Ino-cluster products, C. koseri can exploit the abundant myo-inositol in the brain as a carbon source for growth, thus promoting colonization and virulence.


Subject(s)
Bacterial Proteins/genetics , Citrobacter koseri/metabolism , Citrobacter koseri/pathogenicity , Enterobacteriaceae Infections/microbiology , Genes, Bacterial , Inositol/metabolism , Animals , Bacterial Proteins/metabolism , Biological Transport , Brain/metabolism , Brain/microbiology , Brain/pathology , Citrobacter koseri/genetics , Citrobacter koseri/growth & development , Disease Models, Animal , Enterobacteriaceae Infections/metabolism , Enterobacteriaceae Infections/mortality , Enterobacteriaceae Infections/pathology , Gene Deletion , Gene Expression , Humans , Mice , Mice, Inbred BALB C , Multigene Family , Rats , Rats, Sprague-Dawley , Survival Analysis , Virulence
15.
Environ Sci Technol ; 53(5): 2509-2517, 2019 03 05.
Article in English | MEDLINE | ID: mdl-30758964

ABSTRACT

The retention of polyvinyl chloride (PVC) microplastics in sewage sludge during wastewater treatment raises concerns. However, the effects of PVC microplastics on methane production from anaerobic digestion of waste activated sludge (WAS) have never been documented. In this work, the effects of PVC microplastics (1 mm, 10-60 particles/g TS) on anaerobic methane production from WAS were investigated. The presence of 10 particles/g TS of PVC microplastics significantly ( P = 0.041) increased methane production by 5.9 ± 0.1%, but higher levels of PVC microplastics (i.e., 20, 40, and 60 particles/g TS) inhibited methane production to 90.6 ± 0.3%, 80.5 ± 0.1%, and 75.8 ± 0.2% of the control, respectively. Model-based analysis indicated that PVC microplastics at >20 particles/g TS decreased both methane potential (B0) and hydrolysis coefficient (k) of WAS. The mechanistic studies showed that bisphenol A (BPA) leaching from PVC microplastics was the primary reason for the decreased methane production, causing significant ( P = 0.037, 0.01, 0.004) inhibitory effects on the hydrolysis-acidification process. The long-term effects of PVC microplastics revealed that the microbial community was shifted in the direction against hydrolysis-acidification and methanation. In conclusion, PVC microplastic caused negative effects on WAS anaerobic digestion through leaching the toxic BPA.


Subject(s)
Polyvinyl Chloride , Sewage , Anaerobiosis , Benzhydryl Compounds , Bioreactors , Methane , Phenols , Plastics , Waste Disposal, Fluid
16.
Phys Rev Lett ; 112(18): 185502, 2014 May 09.
Article in English | MEDLINE | ID: mdl-24856706

ABSTRACT

As a fundamental property of a material, density is controlled by the interatomic distances and the packing of microscopic constituents. The most prominent atomistic feature in a metallic glass (MG) that can be measured is its principal diffraction peak position (q1) observable by x-ray, electron, or neutron diffraction, which is closely associated with the average interatomic distance in the first shell. Density (and volume) would naturally be expected to vary under compression in proportion to the cube of the one-dimensional interatomic distance. However, by using high pressure as a clean tuning parameter and high-resolution in situ techniques developed specifically for probing the density of amorphous materials, we surprisingly found that the density of a MG varies with the 5/2 power of q1, instead of the expected cubic relationship. Further studies of MGs of different compositions repeatedly produced the same fractional power law of 5/2 in all three MGs we investigated, suggesting a universal feature in MG.

17.
ACS ES T Water ; 4(6): 2746-2755, 2024 Jun 14.
Article in English | MEDLINE | ID: mdl-38903200

ABSTRACT

Combinations of UV with oxidants can initiate advanced oxidation processes (AOPs) and enhance bacterial inactivation. However, the effectiveness and mechanisms of UV-AOPs in damaging nucleic acids (e.g., antibiotic resistance genes (ARGs)) and cell integrity represent a knowledge gap. This study comprehensively compared ARG degradation and cell membrane damage under three different UV-AOPs. The extracellular ARG (eARG) removal efficiency followed the order of UV/chlorine > UV/H2O2 > UV/peracetic acid (PAA). Hydroxyl radical (•OH) and reactive chlorine species (RCS) largely contributed to eARG removal, while organic radicals made a minor contribution. For intracellular ARGs (iARGs), UV/H2O2 did not remove better than UV alone due to the scavenging of •OH by cell components, whereas UV/PAA provided a modest synergism, likely due to diffusion of PAA into cells and intracellular •OH generation. Comparatively, UV/chlorine achieved significant synergistic iARG removal, suggesting the critical role of the RCS in resisting cellular scavenging and inactivating ARGs. Additionally, flow cytometry analysis demonstrated that membrane damage was mainly attributed to chlorine oxidation, while the impacts of radicals, H2O2, and PAA were negligible. These results provide mechanistic insights into bacterial inactivation and fate of ARGs during UV-AOPs, and shed light on the suitability of quantitative polymerase chain reaction (qPCR) and flow cytometry in assessing disinfection performance.

18.
J Ethnopharmacol ; 330: 118166, 2024 Aug 10.
Article in English | MEDLINE | ID: mdl-38621466

ABSTRACT

ETHNOPHARMACOLOGICAL RELEVANCE: Psoriasis is a chronic inflammatory skin disease. Vitamin D analogues are the first-line topical agents for the long-term management of psoriasis. Chinese herbal medicine (CHM) bath therapy is commonly employed for psoriasis. However, the effects and safety of CHM bath therapy for psoriasis vulgaris, using topical calcipotriol as the comparator, remain inconclusive. Furthermore, the combination of herbs, a distinctive feature of CHM, is essential for its therapeutic effects due to the individual and synergistic properties of the herbs involved. AIM OF THE STUDY: The review was conducted to evaluate the effectiveness and safety of CHM bath therapy for psoriasis vulgaris, using calcipotriol as the comparator. Potential herbs and herb combinations of CHM bath therapy were also explored for further drug discovery. MATERIALS AND METHODS: Nine databases were searched from inception until March 05, 2024. Randomised controlled trials (RCTs) investigating CHM bath therapy, using calcipotriol as the comparator, were included. Statistical analyses were performed using RevMan 5.4, Stata 12.0 and SPSS Clementine 12.0 software. The evidence certainty for outcomes was assessed using the approach proposed by the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group. Moreover, association rule analysis on herbs identified in the systematic review was conducted to explore the potential herbs and herb combinations. RESULTS: A total of 17 RCTs involving 1,379 participants were included in this systematic review. The findings of this review revealed that: 1) CHM bath therapy produced comparable effects to calcipotriol in reducing Psoriasis Area and Severity Index (PASI), Psoriasis Scalp Severity Index (PSSI), and itch visual analogue scale (VAS) at the end of the treatment phase; as well as exhibited a superior long-term effect than calcipotriol through decreasing relapse rates at the end of the follow-up phase; 2) CHM bath therapy showed an additional benefit when combined with calcipotriol in managing psoriasis vulgaris at the end of the treatment phase, in terms of PASI, PSSI, itch VAS, IL-17, IL-23, CD3+ and CD4+ T cells. The certainty of the evidence was rated as 'very low', 'low' or 'moderate' based on the GRADE assessment, considering some concerns or high risk of bias of included studies, substantial heterogeneity, and existing publication bias of some outcomes. Additionally, the proportions of participants reporting adverse events were similar in both groups. Association rule analysis of all included herbs identified 23 herb combinations including Prunus persica (L.) Batsch and Carthamus tinctorius L., as well as 11 frequently used herbs, such as Kochia scoparia (L.) Schrad., Dictamnus dasycarpus Turcz. And Sophora flavescens Ait. CONCLUSIONS: The effects of CHM bath therapy were comparable with those of topical calcipotriol but demonstrated a longer-lasting effect. Combining CHM bath therapy with calcipotriol also provided an additional benefit for adult psoriasis vulgaris. However, the certainty of the evidence was downgraded due to the methodological limitations of included studies. To confirm the findings of this review, future investigations should involve double-blinded, placebo-controlled RCTs. Importantly, it appears worthwhile to consider further research for drug development utilising the identified herbs or herb combinations.


Subject(s)
Calcitriol , Dermatologic Agents , Drugs, Chinese Herbal , Psoriasis , Humans , Baths , Calcitriol/analogs & derivatives , Calcitriol/administration & dosage , Calcitriol/therapeutic use , Dermatologic Agents/administration & dosage , Dermatologic Agents/therapeutic use , Drugs, Chinese Herbal/therapeutic use , Drugs, Chinese Herbal/administration & dosage , Medicine, Chinese Traditional/methods , Psoriasis/drug therapy , Randomized Controlled Trials as Topic , Treatment Outcome
19.
Phytomedicine ; 128: 155381, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38537444

ABSTRACT

BACKGROUND: Chinese herbal medicine (CHM) bath is commonly used in China as an adjuvant therapy for managing psoriasis vulgaris. Previous systematic reviews showed that CHM bath therapy was effective and safe for psoriasis vulgaris, however, without exploration of the specifics of CHM bath therapy such as the optimal temperature, duration of each session, and the total treatment duration. PURPOSE: To evaluate the add-on effects of CHM bath therapy to conventional therapies for adult psoriasis vulgaris. METHODS: We conducted a comprehensive search in nine medical databases from inception to September 2022 to identify relevant randomised controlled trials (RCTs) published in Chinese or English. The included studies compared the combination of CHM bath therapy and conventional therapies to conventional therapies alone for adult psoriasis vulgaris. Methodological quality assessment of the included RCTs was performed using the Cochrane risk-of-bias tool 2 (RoB 2). Statistical analysis was carried out using RevMan 5.4, R 4.2.3 and Stata 12.0 software. The certainty of evidence of outcome measures was evaluated using the Grading of Recommendations Assessment, Development, and Evaluation Working Group (GRADE) system. RESULTS: A total of 23 RCTs involving 2,183 participants were included in this systematic review. Findings suggested that the combination of CHM bath therapy and conventional therapies was more effective in reducing Psoriasis Area and Severity Index (PASI), Dermatology Life Quality Index (DLQI) and itch visual analogue scale, compared to using conventional therapies alone. These enhanced effects were notably observed when the CHM bath was set above 38 °C and had a duration of 20 and 30 min, as assessed by DLQI. Moreover, an eight-week treatment duration resulted in better effects for PASI compared to shorter durations. Additionally, the top ten frequently used herbs in the included studies were identified. Despite the findings, the certainty of evidence was rated as 'low' or 'moderate' based on the GRADE assessment, and significant heterogeneity was detected in subgroup and sensitivity analyses. CONCLUSION: The CHM bath therapy combined with conventional therapies is more effective and safer than conventional therapies alone for adult psoriasis vulgaris. The results suggest a potential correlation between treatment effects and factors such as extended treatment duration, increased bath temperature, and longer bath sessions. However, the certainty of evidence was downgraded due to methodological limitations of the included studies. To confirm the findings of this systematic review, a double-blinded, placebo-controlled RCT is needed in the future.


Subject(s)
Baths , Drugs, Chinese Herbal , Psoriasis , Randomized Controlled Trials as Topic , Psoriasis/drug therapy , Psoriasis/therapy , Humans , Drugs, Chinese Herbal/therapeutic use , Baths/methods , Combined Modality Therapy , Medicine, Chinese Traditional/methods , Phytotherapy
20.
Bioresour Technol ; 396: 130445, 2024 Mar.
Article in English | MEDLINE | ID: mdl-38346595

ABSTRACT

To realize the intelligent production of straw bales and improve their economy, the density of straw bales in the working process of large-scale steel roller-type round balers must be measured in real time. Therefore, this study analyzes the forces acting on steel rollers and bales in the bale rolling process, constructs a mathematical model to predict the density of molded bales, and proposes a method for dynamically measuring the density of bales in a round bale machine. Sunflower straw was selected as the test material, and a bale density model validation test was conducted at a test stand. The results showed that the accuracy of the measured bale density of the data acquisition system ranged from 93% to 97%, verifying that the mathematical model for bale density prediction had good accuracy. This study provided an effective strategy for round baler design.


Subject(s)
Models, Theoretical
SELECTION OF CITATIONS
SEARCH DETAIL