Apparent Constant Research Articles

Melamine enhancing Cu-Fenton reaction for degradation of anthracyclines

Melamine (MA) enhanced Cu-Fenton process was developed for the degradation of anthracyclines. Taking daunorubicin (DNR) degradation as an example, we found that the initial first-order apparent constant of Cu2+/MA/H2O2 system with a molar ratio of 1:8 for Cu2+:MA was 5.2 times higher than that of conventional Cu2+/H2O2 system. The in-situ reductive coordination between Cu2+ and MA facilitated the generation and stabilization of Cu+ species, thereby accelerating the rate-limiting step of Cu2+/Cu+ conversion and maintaining high levels of Cu+ during the degradation process. Moreover, pre-synthesized Cu+-MA complexes (e.g., CM-250) further enhanced the efficiency of the Cu-Fenton reaction by increasing both the Cu+ proportion and MA chelation. The apparent activation energy for DNR degradation in CM-250 mediated Fenton reaction (15.9 kJ mol−1) was lower than that in systems involving Cu2+/MA (41.2 kJ mol−1) and Cu2+ (65.6 kJ mol−1). Enhanced generation of various reactive oxygen species (·OH,·O2-, and 1O2) was confirmed, with 1O2 playing a dominant role, significantly improving both degradation rate and mineralization degree for DNR. MA-enhanced Cu-Fenton process also offers a convenient alternative to effectively remove other anthracyclines and organic micropollutants, holding great promise for advancing advanced oxidation processes as well as practical large-scale degradation applications targeting multiple pollutants.

Microbial community respiration kinetics and their dynamics in coastal seawater

Oxygen (O2) concentrations in coastal seawater have been declining for decades and models predict continued deoxygenation into the future. As O2 declines, metabolic energy use is progressively channelled from higher trophic levels into microbial community respiration, which in turn influences coastal ecology and biogeochemistry. Despite its critical role in deoxygenation and ecosystem functioning, the kinetics of microbial respiration at low O2 concentrations in coastal seawater remain uncertain and are mostly modeled based on parameters derived from laboratory cultures and a limited number of environmental observations. To explore microbial responses to declining O2, we measured respiration kinetics in coastal microbial communities in Hong Kong over the course of an entire year. We found the mean maximum respiration rate (Vmax) ranged between 560 ± 280 and 5930 ± 800 nmol O2 L−1 h−1, with apparent half-saturation constants (Km) for O2 uptake of between 50 ± 40 and 310 ± 260 nmol O2 L−1. These kinetic parameters vary seasonally in association with shifts in microbial community composition that were linked to nutrient availability, temperature, and biological productivity. In general, coastal communities in Hong Kong exhibited low affinities for O2, yet communities in the dry season had higher affinities, which may play a key role in shaping the relationship between community size, biomass, and O2 consumption rates through respiration. Overall, parameters derived from these experiments can be employed in models to predict the expansion of deoxygenated waters and associated effects on coastal ecology and biogeochemistry.

Rare Earth Element Binding and Recovery by a Beta Roll-Forming RTX Domain.

The Block V of the RTX domain of the adenylate cyclase protein from Bordetella pertussis is disordered, and upon binding eight calcium ions, it folds into a beta roll domain with a C-terminal capping group. Due to their similar ionic radii and coordination geometries, trivalent lanthanide ions have been used to probe and identify calcium-binding sites in many proteins. Here, we report using a FRET-based assay that the RTX domain can bind rare earth elements (REEs) with higher affinities than calcium. The apparent disassociation constants for lanthanide ions ranged from 20 to 75 μM, which are an order of magnitude higher than the affinity for calcium, with a higher selectivity toward heavy REEs over light REEs. Most proteins release bound ions at mildly acidic conditions (pH 5-6), and the high affinity REE-binding lanmodulin protein can bind 3-4 REE ions at pH as low as ∼2.5. Circular dichroism (CD) spectra of the RTX domain demonstrate pH-induced folding of the beta roll domain in the absence of ions, indicating that protonation of key amino acids enables structure formation in low pH solutions. The beta roll domain coordinates up to four ions in extreme pH conditions (pH < 1), as determined by equilibrium ultrafiltration experiments. Finally, to demonstrate a potential application of the RTX domain, REE ions (Nd3+ and Dy3+) were recovered from other non-REEs (Fe2+ and Co2+) in a NdFeB magnet simulant solution (at pH 6).

A dual-purpose photocatalytic reaction for hydrogen evolution and simultaneous organic pollutant degradation of V2O5/Ppy based composite photocatalyst

The present work reports for the facile synthesis of novel vanadium oxide/polypyrrole (V2O5/Ppy) nanohybrids using various loadings of the V2O5. This novel hybrid photocatalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman, UV–Visible absorption spectra (UV–Vis), photoluminescence spectra (PLS) and N2 adsorption-desorption analysis. XRD and TEM results suggest that V2O5 with individual spherical shaped nanoparticles of around 20–25 nm, which is uniformly wrapped on the surface of the Ppy sheets. A significant reduction in the bad gap energy (3.06–2.13 eV) and prevent the electron-hole recombination process was examined by UV and PL studies. The photocatalytic degradation efficiency was carried out for Reactive Black 31 (RB 31) and 4-chlorophenol (4-CP) dyes under visible light. The results illustrate that the optimal hybrid catalyst could reach 99 % of removal efficiency towards RB31 with visible light irradiation for 60 min. Moreover, the catalyst show high TOC efficiency (88%) high apparent constant (0.9189 min−1), and good stability with multiple cycle experiments. The improved photocatalytic mechanism was also discussed in detail. In comparison to V2O5 (425 μmol−1h−1 of H2) and PPy (151 μmol−1h−1 of H2), the optimised composite, 15 wt% V2O5 incorporated PPy showed a remarkable production rate under visible light (2255 μmol−1h−1 of H2).

Synthesis of Cu doped NiO for their antioxidant and photocatalytic properties: Green synthesis using Lycopodium Linn

Metal oxide nanoparticles produced by plant extracts are more stable and biocompatible in comparison with those produced by physical and chemical methods. This research focuses on the synthesis of pure and Cu doped NiO nanoparticles (NPs) using Phytolacca dodecandra L'Herit (P.d) leaf extract and evaluation of their antioxidant and photocatalytic activities. The obtained Cu-doped NiONPs have been characterized through X-ray diffraction (XRD), Transmission electron microscope (TEM), Fourier transform infrared (FT-IR), Ultraviolet-visible (UV–Vis), N2 adsorption-desorption and X-ray photoelectron spectra (XPS) analyses in different concentrations (1, 3, and 5 %) of copper at an optimum temperature of 400 °C. The photocatalytic activity of prepared samples was studied by degradation of Rose Bengal (RB) and Methylene Blue (MB) dye aqueous solutions. Under UV radiation for 60 min. 5-Cu-NiO nanophotocatalyst showed degradation efficiency of 98.7 % (0.5 mol/L), high apparent constant (0.9871 min−1) and long term stability towards MB dye. In the antioxidant test, NiO NPs and Cu−NiO NPs prevented the oxidation of 50 % of the H2O2 molecules at a concentration of 363.96 and 350.29 μg/mL, respectively. Moreover, the enhancement of the antioxidant activity of the biosynthesized NiO NPs might be an effect of copper ions present in the particles. Facile and green synthesis process with the excellent degradation performance demonstrates that the Cu doped NiO NPs have a great potential for wastewater treatment applications.

The superiority of hydrophilic polyurethane in comammox-dominant ammonia oxidation during low-strength wastewater treatment

Carriers have been extensively employed to enhance nitrification performance during low-strength wastewater treatment by retaining slow-growing ammonia oxidizing microorganisms (AOMs). Still, there is a dearth of systematic understanding of biofilm properties and microbial community structure formed on different carriers. In this study, hydrophilic polyurethane foam (PUF) carriers were prepared and compared with five widely used commercial carriers, namely Kaldness 3, Biochip, activated carbon, volcanic rock, and zeolite. The results indicated that the biofilms formed on carriers enhanced microbial ammonia oxidation activity. Additionally, the biofilm developed on the PUF demonstrated the most superior performance among all selected carriers, not only exhibiting the highest abundant and the most active AOMs, with amoA gene abundance of 1.41 × 1013 copies/m3 and specific ammonia oxidation rate of 9.84 g NH4+-N/(m3 × h), but also possessing a compact structure, with 3.41 kg VSS/m3 and 46.83 mg extracellular polymeric substances/g VSS. The high-throughput sequencing analysis revealed that the comammox (CMX) Nitrospira dominated on biofilm due to the intrinsically low apparent half-saturation constant for substrate. A unique ecological community structure was established on PUF, characterized by low species diversity and high homogeneity in alignment with community characteristics of CMX. The biofilms on PUF contributed to the proliferation of CMX Nitrospira dominated by Nitrospira nitrosa, achieving the highest proportion among colonial three AOMs at 86.58 %. The appropriate average pore size, superior hydrophilicity, and large specific surface area of PUF carriers provided a robust foundation for the exceptional ammonia oxidation performance of the formed biofilms.

Silk nanoribbon films with enriched silk II structure and enhanced piezoelectricity for self-powered implantable and wearable devices

Piezoelectric biomaterials are intrinsically suitable to convert mechanical energy to electrical output and achieve electricity generation, in vivo/in vitro real-time monitoring, and sensing in biological systems. However, the inability to fabricate piezoelectric bio-materials with excellent piezoelectricity, full biodegradability, and good biocompatibility remains a challenge toward practical applications. As a solution, we present a bio-piezoelectric thin film with macroscopic piezoelectric output, high stability, fast response ability, flexibility, biocompatibility, and biodegradability based on nascent silk nanoribbons (SNRs) with high silk II-type structure. The solvent systems influence the meso/nanostructure and the piezoelectric performance of silk materials. Compared with other silk materials, the SNR fabricated by 2,2,6,6-tetramethylpiperidine-1-oxyl oxidation system (T-SNR) maintains higher silk II-type structure and more stable crystalline structure. The T-SNR film possesses electrostriction effect without electrical poling treatment. It presents an apparent piezoelectric constant (d33) of 7.7 pm/V and a piezoelectric voltage coefficient (g33) of 0.58 Vm/N, such values are superior to most reported bio-films. The piezoelectric T-SNR film can realize in vivo/in vitro real-time monitoring, sensing, and self-power ability. With its natural compatibility and degradability, the T-SNR film exhibits the potential for various implantable and wearable applications and may enable the development of fully biodegradable transient electromechanical devices.

Hyperpolarized 15N caffeine, a potential probe of liver function and perfusion.

To demonstrate hyperpolarization of 15N-caffeine and report exploratory findings as a potential probe of liver function and perfusion. An amorphous formulation of [1,3-15N2]caffeine was developed for hyperpolarization via dissolution dynamic nuclear polarization. Polarizer hardware was augmented to support monitoring of solid-state 15N MR signals during the buildup of hyperpolarization. Liquid state hyperpolarized 15N MR signals were obtained in a preclinical 3T magnet by interfacing an external spectrometer console with home-built RF surface coils. 15N signal decay constants were estimated in H2O and in vivo in liver and brain regions of rats at 3 T. Decays were also measured at 9.4 T to assess the effect of B0, and in the presence of albumin to assess the impact of protein binding. Polarization levels of 3.5% and aqueous T1 relaxation times of nearly 200 s were attained for both N1and N3 positions at 3 T. Shorter apparent decay constants were observed in vivo, ranging from 25 s to 43 s, with modest extensions possible by exploiting competitive binding of iophenoxate with plasma albumin. Downstream products of caffeine could not be detected on in vivo 15N-MR spectra of the liver region, even with metabolic stimulation by -naphthoflavone treatment. Considering the high perfusion rate of brain, persistence of caffeine signal in this region is consistent with potential value as a perfusion imaging agent. These results establish the feasibility of hyperpolarization of hyperpolarized 15N-caffeine, but further work is necessary to establish the role of this new agent to probe liver metabolism and perfusion.

Equilibrium characteristics of sorption of some phenolic compounds by FIBAN A-1 fiber from aqueous solutions

Many phenolic compounds are related to the group of toxic substances, the occurrence of which in wastewater has a negative impact on the environment. In addition to extraction, biochemical, and membrane methods for the isolation of hydroxybenzenes from aqueous media, sorption methods using active carbon, nonionic polymers, and ion-exchange materials are also actively used. The purpose of this work was to establish the features of the sorption of phenol, resorcinol and phloroglucinol from aqueous solutions with FIBAN fibers. Sorption was studied under static conditions at a temperature of 298 K. An assessment of the amount of absorbed sorbates by fibers of various nature indicates that FIBAN A-1 fiber exhibits better capacity characteristics relative to phenolic compounds. This fact is due to the nature of the matrix (styrene-divinylbenzene) and the high basicity of the functional groups of this sorbent, which increase the number of sorption centers for the uptake of hydroxybenzenes. The isotherms of the sorption of phenol, resorcinol and phloroglucin in the concentration range 0.5-10 mmol/dm3 indicate the affinity of FIBAN A-1 to these sorbates. In the entire range of concentrations studied, the highest recovery rates are characteristic of trihydroxybenzene. The paper provides a formal analysis of the obtained equilibrium curves based on the choice of the sorption equation that most closely describes the experimental dependences. The apparent constants of sorption equilibrium are calculated, the energy characteristics of uptake process are estimated.

Quantitative at-line monitoring of enzymatic hydrolysis using benchtop diffusion nuclear magnetic resonance spectroscopy.

Benchtop diffusion nuclear magnetic resonance (NMR) spectroscopy was used to perform quantitative monitoring of enzymatic hydrolysis. The study aimed to test the feasibility of the technology to characterize enzymatic hydrolysis processes in real time. Diffusion ordered spectroscopy (DOSY) was used to measure the signal intensity and apparent self-diffusion constant of solubilized protein in hydrolysate. The NMR technique was tested on an enzymatic hydrolysis reaction of red cod, a lean white fish, by the endopeptidase alcalase at 50°C. Hydrolysate samples were manually transferred from the reaction vessel to the NMR equipment. Measurement time was approximately 3 min per time point. The signal intensity from the DOSY experiment was used to measure protein concentration and the apparent self-diffusion constant was converted into an average molecular weight and an estimated degree of hydrolysis. These values were plotted as a function of time and both the rate of solubilization and the rate of protein breakdown could be calculated. In addition to being rapid and noninvasive, DOSY using benchtop NMR spectroscopy has an advantage compared with other enzymatic hydrolysis characterization methods as it gives a direct measure of average protein size; many functional properties of proteins are strongly influenced by protein size. Therefore, a method to give protein concentration and average size in real time will allow operators to more tightly control production from enzymatic hydrolysis. Although only one type of material was tested, it is anticipated that the method should be applicable to a broad variety of enzymatic hydrolysis feedstocks.

Investigating Cu(I) binding to model peptides of N-terminal Aβ isoforms

Amyloid beta (Aβ) peptides and copper (Cu) ions are each involved in critical biological processes including antimicrobial activity, regulation of synaptic function, angiogenesis, and others. Aβ binds to Cu and may play a role in Cu trafficking. Aβ peptides exist in isoforms that vary at their C-and N-termini; variation at the N-terminal sequence affects Cu binding affinity, structure, and redox activity by providing different sets of coordinating groups to the metal ion. Several N-terminal isoforms have been detected in human brain tissues including Aβ1–40/42, Aβ3–42, pEAβ3–42, Aβ4–42, Aβ11–40 and pEAβ11–40 (where pE denotes an N-terminal pyroglutamic acid). Several previous works have individually investigated the affinity and structure of Cu(I) bound to some of these isoforms' metal binding domains. However, the disparately reported values are apparent constants collected under different sets of conditions, and thus an integrated comparison cannot be made. The work presented here provides the Cu(I) coordination structure and binding affinities of these six biologically relevant Aβ isoforms determined in parallel using model peptides of the Aβ metal binding domains (Aβ1–16, Aβ3–16, pEAβ3–16, Aβ4–16, Aβ11–16 and pEAβ11–16). The binding affinities of Cu(I)-Aβ complexes were measured using solution competition with ferrozine (Fz) and bicinchoninic acid (BCA), two colorimetric Cu(I) indicators in common use. The Cu(I) coordination structures were characterized by X-ray absorption spectroscopy. The data presented here facilitate comparison of the isoforms' Cu-binding interactions and contribute to our understanding of the role of Aβ peptides as copper chelators in healthy and diseased brains.

A eco-friendly, low cost green synthesis of Ag@Sm2O3/rGO nanocomposites with enhanced UV light photocatalytic and antimicrobial activity

In this research, we investigated the potential of a leaf extract from the Punica Granatum peel as a reducing and capping agent in the manufacture of a nanocomposite consisting of Ag-doped Sm2O3 nanoparticles encased in reduced graphene oxide (rGO). XRD, SEM, TEM, FTIR, XPS, PL, and DRS were all used to confirm the performance and characterisation of nanocomposite materials. Photocatalytic degradation studies of 4-nitrophenol (4-NP) and methylene blue (MB) provided interesting insights into the photocatalytic activity of Ag@Sm2O3/rGO. The results show that Ag@Sm2O3 particles between 10 nm and 20 nm in size are uniformly distributed across the RGO surface. Maximum photodegradation efficiency towards MB (96.7 %), high apparent constant (0.8716 min−1), and long-term stability under UV light exposure are all achieved when rGO is combined with Ag@Sm2O3 as the photocatalyst. It was confirmed that certain types of bacteria and fungi responded differently to the antibacterial properties of doped and undoped nanoparticles. The surface surface plasmon resonance (SPR) of Ag NPs had a role in the relationship between Sm2O3 nanoparticles and rGO sheets, which led to this finding. A novel Sm2O3-based photocatalyst with high solar absorption and higher catalytic activity is proposed, and a viable mechanism for developing such a material is shown in this study.

Origin of Long-Range Hyperfine Couplings in the EPR Spectra of 2,2,5,5-Tetraethylpyrrolidine-1-oxyls.

Cyclic nitroxides with several bulky alkyl substituents adjacent to the nitroxide group are known to demonstrate a much higher stability to bioreduction than their tetramethyl analogues. Among these so-called "sterically shielded" nitroxides, the pyrrolidine derivatives are the most stable. The EPR spectra of some sterically shielded pyrrolidine-1-oxyls were reported to show one or two large additional doublet splittings with a hyperfine coupling (hfc) constant (ca. 0.2-0.4 mT). To determine the origin of these hfc, a series of 2-R-2,5,5-triethyl-3,4-bis(hydroxymethyl)-pyrrolidine-1-oxyls with methylene groups stereospecifically enriched with deuterium were prepared, and their CW EPR spectra were studied. In addition, these nitroxides were investigated using quantum chemical calculations on the UB3LYP/def2-TZVP level and NBO analysis. The apparent constants were assigned to hfc with γ-hydrogen in the side chain, with the contribution of the NBO orbital βπ*(N-O) to the natural localized molecular orbital βσ(C-H) playing the major role. This interaction is efficient if the ethyl substituent is in the pseudoaxial position of the ring and the CH2-CH3 bond is codirected with (parallel to) N-O. The apparent constant aH increases with the Boltzmann population of this conformation.

Continuous removal of caffeine in a horizontal-flow anaerobic immobilized biomass bioreactor: identification of transformation products.

Anaerobic bioreactors are an efficient technology for the biodegradation of emerging contaminants in environmental matrices. In this work, a horizontal-flow anaerobic immobilized biomass (HAIB) bioreactor was used to remove caffeine (CAF), which is frequently found in various aqueous matrices. The acrylic bench top bioreactor, with dimensions of 100 × 5.00cm, was operated with a hydraulic retention time (HRT) of 12h, during 45weeks, under mesophilic conditions. The operation was performed in 4 phases: without CAF addition (phase I); CAF spiked at 300μg L-1 (phase II); CAF at 600μg L-1 (phase III); and CAF at 900μg L-1 (phase IV). Samples of bioreactor influent and effluent were analyzed by liquid chromatography/tandem mass spectrometry (LC-MS/MS). The bioreactor removed organic matter (OM) and CAF with efficiencies of 88 and 93%, respectively. The first-order apparent removal constant (Kapp) values for OM and CAF were 0.419 and 0.304h-1, respectively. Five transformation products (TPs) were identified, with m/z 243, 227, 211, and 181 (two products). The HAIB bioreactor is a suitable system for the removal of CAF present in wastewater, even at a concentration level of µg L-1.

Bi2MoO6 nanoflower-like microsphere photocatalyst modified by boron doped carbon quantum dots: Improving the photocatalytic degradation performance of BPA in all directions

Bi-based semiconductor photocatalyst represented by Bi2MoO6 (BMO) has obvious advantages in the degradation of bisphenol A (BPA), but three prominent problems that restrict the improvement of photocatalytic performance, namely, insufficient solar absorption, less active sites and serious photogenerated carrier recombination, need to be solved urgently. For this reason, we specially designed a simple structure of B-doped carbon quantum dots (BCQDs) modified BMO nanoflower-like microsphere composite to improve the photocatalytic performance of the system from the above three dimensions. The optimized BCQDs/BMO sample completely degraded BPA within 120 min under simulated sunlight, corresponding to an apparent constant of 0.03453 min−1, while the control sample of CQDs/BMO without B doping only degraded about 84 % of BPA within 160 min, with an apparent coefficient of 0.01138 min−1. Even after filtering out UV components below 400 nm, the degradation performance of the optimal composite catalyst did not decrease. The improved catalytic performance comes from the excellent up-conversion luminescence performance and good electron storage capacity of CQDs on the one hand, and the introduction of B on the other hand can adjust the surface structure of CQDs to generate more active sites and functional interfaces to further promote the catalytic reaction. Free radical trapping and electron spin resonance (ESR) tests have shown that·OH and·O2- are the main active substances in the degradation of BPA. The current BCQDs/BMO catalysts, despite their simple structure, can simultaneously improve the catalytic performance from the three important aspects mentioned above, which will guide the design of others semiconductor based photocatalysts.

Application of a KOH-activated biochar for the activation of persulfate and the degradation of sulfamethoxazole

In this work, valorized biomass was simultaneously pyrolyzed and activated with potassium hydroxide to produce a biochar with specific surface area of 1148 m2g−1, i.e. ten times greater than the pristine material, and significant amounts of surface oxygen species and carbonates, as evidenced by XRD and FTIR characterization. The activated biochar (50–250 mgL−1) was employed for a first time as sodium persulfate (100–750 mgL−1) activator to induce the adsorption/oxidation of sulfamethoxazole (SMX: 0.25–1.5 mgL−1), a representative emerging micropollutant, in various water matrices, including the detailed study of different parameters in wastewater. In general, the degradation follows pseudo-first order kinetic law and the apparent constant was found to increase with increasing biochar, persulfate concentration and acidity of the solution and decreasing with SMX concentration, matrix complexity (from surface water or ultrapure water to actual or simulated wastewater). The mechanism of oxidation is mainly through radical pathway and/or electron transfer, while singlet oxygen’s contribution is inconsiderable, as evidenced by scavenging experiments and the structure of the various identified transformation products.

Characterisation of bacteria representing a novel Nitrosomonas clade: Physiology, genomics and distribution of missing ammonia oxidizer.

Members of the genus Nitrosomonas are major ammonia oxidizers that catalyse the first step of nitrification in various ecosystems. To date, six subgenus-level clades have been identified. We have previously isolated novel ammonia oxidizers from an additional clade (unclassified cluster 1) of the genus Nitrosomonas. In this study, we report unique physiological and genomic properties of the strain PY1, compared with representative ammonia-oxidising bacteria (AOB). The apparent half-saturation constant for total ammonia nitrogen and maximum velocity of strain PY1 were 57.9 ± 4.8 μM NH3 + NH4 + and 18.5 ± 1.8 μmol N (mg protein)-1 h-1 , respectively. Phylogenetic analysis based on genomic information revealed that strain PY1 belongs to a novel clade of the Nitrosomonas genus. Although PY1 contained genes to withstand oxidative stress, cell growth of PY1 required catalase to scavenge hydrogen peroxide. Environmental distribution analysis revealed that the novel clade containing PY1-like sequences is predominant in oligotrophic freshwater. Taken together, the strain PY1 had a longer generation time, higher yield and required reactive oxygen species (ROS) scavengers to oxidize ammonia, compared with known AOB. These findings expand our knowledge of the ecophysiology and genomic diversity of ammonia-oxidising Nitrosomonas.

Controllable fabrication of Bi4Ti3O12/C/Bi2S3/MoS2 heterojunction with effective suppression of Bi2S3 assisted by amorphous carbon interlayer for significantly enhanced photocatalysis

BackgroundFabricating heterojunctions by combining with MoS2 is efficient to boost the visible light photocatalytic activity of Bi4Ti3O12 (BTO) but limited by the concurrent formation of Bi2S3 nanorods by in-situ ion exchange reaction. MethodsAn amorphous carbon interlayer that can effectively protect the BTO fibrous structure and suppress the Bi2S3 generation was introduced to construct Bi4Ti3O12/C/Bi2S3/MoS2 (BCBM) composites with enhanced photocatalytic activity. The BCBM fibers were fabricated by electrospinning and subsequent hydrothermal growth of carbon and MoS2. Significant findingsOwing to the important roles of carbon interlayer to keep the integrity of the BTO fibrous structure and provide charge transfer channel, fast separation of photoinduced carriers happens on the semiconductor interface between BTO and MoS2 to improve the visible light photocatalytic activity. The optimum BCBM displays a photocatalytic efficiency of 88.4% and apparent constant of 0.0148 min−1 towards degrading RhB, which are much higher relative to the Bi4Ti3O12/Bi2S3/MoS2 composites prepared without the carbon interlayer. Moreover, it is demonstrated that the thickness of carbon interlayer is crucial for fabricating high-performance BTO heterojunctions with MoS2. The design and results in this work may broaden the horizon to construct the Bi-based semiconductor photocatalyst with high photocatalytic performance.

Scyllo-inositol: Transverse relaxation time constant at 3T and concentration changes associated with aging and alcohol use.

The goals of this study were to measure the apparent transverse relaxation time constant, T2 , of scyllo-inositol (sIns) in young and older healthy adults' brains and to investigate the effect of alcohol usage on sIns in young and older healthy adults' brains, using proton magnetic resonance spectroscopy (MRS) at 3T. Twenty-nine young adults (age 21 ± 1years) and 24 older adults (age 74 ± 3years) participated in this study. MRS data were acquired from two brain regions (the occipital cortex and posterior cingulate cortex) at 3T. The T2 of sIns was measured using a localization by adiabatic selective refocusing (LASER) sequence at various echo times, while the sIns concentrations were measured using a short-echo-time stimulated echo acquisition mode (STEAM) sequence. A trend towards lower T2 relaxation values of sIns in older adults was observed, although these were not significant. sIns concentration was higher with age in both brain regions and was significantly higher in the young when considering alcohol consumption of more than two drinks per week. This study shows that differences in sIns can be found in two distinct regions of the brain across two age groups, potentially reflecting normal aging. In addition, it is important to take into account alcohol consumption when reporting the sIns level in the brain.

Neutralizing Carbapenem Resistance by Co-Administering Meropenem with Novel β-Lactam-Metallo-β-Lactamase Inhibitors.

Virulent Enterobacterale strains expressing serine and metallo-β-lactamases (MBL) genes have emerged responsible for conferring resistance to hard-to-treat infectious diseases. One strategy that exists is to develop β-lactamase inhibitors to counter this resistance. Currently, serine β-lactamase inhibitors (SBLIs) are in therapeutic use. However, an urgent global need for clinical metallo-β-lactamase inhibitors (MBLIs) has become dire. To address this problem, this study evaluated BP2, a novel beta-lactam-derived β-lactamase inhibitor, co-administered with meropenem. According to the antimicrobial susceptibility results, BP2 potentiates the synergistic activity of meropenem to a minimum inhibitory concentration (MIC) of ≤1 mg/L. In addition, BP2 is bactericidal over 24 h and safe to administer at the selected concentrations. Enzyme inhibition kinetics showed that BP2 had an apparent inhibitory constant (Kiapp) of 35.3 µM and 30.9 µM against New Delhi Metallo-β-lactamase (NDM-1) and Verona Integron-encoded Metallo-β-lactamase (VIM-2), respectively. BP2 did not interact with glyoxylase II enzyme up to 500 µM, indicating specific (MBL) binding. In a murine infection model, BP2 co-administered with meropenem was efficacious, observed by the >3 log10 reduction in K. pneumoniae NDM cfu/thigh. Given the promising pre-clinical results, BP2 is a suitable candidate for further research and development as an (MBLI).