Maximum Intensity Research Articles

Experimental investigation of FSW induced property changes in welded dissimilar Mg–Al–Zn alloys

Intense plastic deformation and intermixing during friction stir welding of dissimilar alloys may suppress the properties in welded zone. To suitably control these changes, careful study is required. Present research investigates microstructure, mechanical performance and corrosion behaviour at different rotational speeds in friction stir welded dissimilar AZ31–AZ91 Mg alloys. Very small cracks were present in welded zone due to formation of magnesium oxide (MgO). The EBSD analysis suggest more concentrated fibre texture at 1000 rpm tool rotational speed as compared to 700 rpm tool rotational speed in welded zone and the texture maximum intensity was 39.447 times of random distribution at tool rotational speed of 1000 rpm. The obtained maximum microhardness was 82 Hv at tool rotational speed of 700 rpm. The maximum values of tensile strength (234.86 ± 7.77 MPa) and flexural strength (350.89 ± 17.67 MPa) of welded samples were decreased as compared to base materials. The corrosion rate of welded samples was increased and corroded surface have some pits and corroded rings. The highest corrosion rate (2.1596 mm / year ) was obtained at 700 rpm. This experimental work suggests that in overall, sample welded at 1000 rpm tool rotational speed has better weld property.

Optically Pure Co(III) Complex Absorbed by Electrochemiluminescence-Active Covalent Organic Framework as an Enantioselective Recognition Platform to Give Opposite Responses Toward Amino Alcohol Enantiomers.

Although covalent organic frameworks (COFs) accompanied by electrochemiluminescence (ECL) behavior have been introduced in recent years, they are still rarely applied for ECL-based enantioselective sensing, especially giving high recognition efficiency. In the current study, an achiral ionic COF comprised of the pyridinium unit is synthesized in the linkage of the carbon-nitrogen cation bond through the Zincke reaction. Interestingly, the synthesized ionic COF can generate clear ECL owing to the presence of electroactive species. Then, the ECL-active achiral COF is employed to absorb the chiral Co(III) complex for enantioselective sensing. As a result, the developed ECL sensor displays discriminative responses toward amino alcohol enantiomers. When the chiral Co(III) complex with (R)-configuration is used, the examined (S)-amino alcohols result in ECL enhancement, whereas (R)-amino alcohols lead to ECL quenching. The maximum ECL intensity ratio between (S)- and (R)-amino alcohols is up to 47.7. In addition, the recognition mechanism is investigated in detail. Finally, a good linear relation between enantiomeric composition and ECL intensity is developed and appropriate for the accurate analysis of the enantiomeric purities of unknown samples. In short, we believe that this study constructs an effective strategy to combine the respective advantages of COFs and ECL for high-efficiency enantioselective sensing.

Bias disk boost technique for pulsed-operation electron cyclotron resonance ion sources

A simple, effective technique to increase the intensity of multiply charged ions has been developed for pulsed-operation electron cyclotron resonance ion sources (ECRISs). The technique is realized simply by applying an additional boost voltage of about −1 kV to a negative constant voltage on the bias disk. The technique can be applied to general ECRISs by adding electric devices to the bias disk circuit, such as a high-voltage power supply, a fast high-voltage switch, and a diode. The effect of the technique depends on the ion species, and we obtained a maximum ion intensity increase of 66% for O6+ compared with the conventional bias disk method. In particular, the technique can be applied to the existing pulsed-operation ECRISs used at a heavy-ion cancer therapy facility where multi-ion treatment with multiply charged oxygen and neon ions is planned to be introduced.

Current summer heat waves impair rainbow trout (Oncorhynchus mykiss) spermatogenesis: Implications for future fish farming management practices in South Europe

Freshwater environments provide different ecosystem services for human well-being, and are one of the most important natural sources of healthy animal protein. Climate change and extreme temperature events, among other factors, represent a growing concern for their sustainable use. In contrast to the research effort to elucidate how global warming affects these aquatic environments, few studies pay attention to the potential effects of heat waves, a current phenomenon with direct effects on contemporaneous organisms. Here, the potential effects of a single heat wave event on rainbow trout (Oncorhynchus mykiss) males, mimicking a recorded environmental event, have been evaluated by means of biometric, redox and stress response, plasma testosterone, histopathology and transcriptomic analyses. Environmental monitoring showed how, during the last 4 years, mean water temperature increased (2–4 °C; from April to October), heat wave duration progressively increased (from 15 to 100 days), and mean intensities ranged 1.7–3.8 °C with a maximum of 8.0 °C. An experimentally recreated heat wave lasting only 16 days, with mean and maximum intensities of 2.7 and 6.7 °C, induced a decrease in body weight and total antioxidant status, but increased blood plasma cortisol levels and redox enzyme activity. The induced heat wave decreased testosterone plasma levels and sperm quality, arrested spermatocyte type I and II differentiation and increased spermatozoa apoptosis. These effects were correlated with a differential expression of 1156 genes (116 up- and 1040 down-regulated genes) in exposed fish when compared to Control fish, reflecting an alteration in cell apoptosis and spermatozoa maturation processes. These results not only increase concern about current heat wave events, recreating a real scenario, but also unveil for the first time the particular molecular mechanisms of subsequent spermatogenesis disruption, opening new avenues for designing urgent and necessary strategies to mitigate the effects of extreme climate change conditions on freshwater aquaculture.

Preparation, characterization and emission of Na3-3xLnxFe2(PO4)3 (Ln = Eu, Tb; 0 ≤ x ≤ 0.1 mol %) and photocatalytic activity of Na3Fe2(PO4)3

Rare earth doped compositions Na3-3xLnxFe2(PO4)3 (x = 0, 0.025, 0.05, 0.075 and 0.1) were prepared by ion-exchange method using Na3Fe2(PO4)3 and LnCl3 (Ln = Eu and Tb). Pristine Na3Fe2(PO4)3 was obtained by ethylene glycol assisted gel burning procedure. The phase characterization was performed by powder X-ray diffraction (XRD). All the compositions were well crystalized in monoclinic lattice. The FE-SEM images and elemental mapping were obtained. The infrared and Raman profiles of all-compounds were dominated by the bands owing to the (PO4) units. Investigation on photoluminescence emission and excitation spectra of Ln3+ (Ln = Eu, Tb) were carried out. The excitation spectra of Na3-3xLnxFe2(PO4)3 (Ln = Eu and Tb) gave intensive band at 256 (370) nm for Eu (Tb) doped phosphors. The photoluminescence emission spectra of Ln3+ (Ln = Eu, Tb) were carried out. The emission spectra of these composition were characterized by f -f transitions corresponding to 613 (5D0→7F2) for Eu and 543 (5D4→7F5) for Tb doped compositions. The maximum emission intensity for Eu (Tb) doped phosphors was found at x = 0.075 (0.05). The analysis of CIE and CCT values of all prepared phosphors were also carried out. Decay curves were analyzed in detail. The visible-light photo-catalytic activity of parent Na3Fe2(PO4)3 was examined against decomposition of methylene blue and methyl orange dyes. Parent Na3Fe2(PO4)3 exhibits good efficiency against MB (≈94.5 %) and moderate efficiency against MO (≈64 %) in 180 min of visible light irradiation. Scavengers’ experiments were carried to identify the active species during photodegradation.

Psychotic Experiences Questionnaire. Part 2

BACKGROUND: On the basis of the concept of psychotic and psychotic-like experiences, delusions and auditory hallucinations presented in Part 1 of this article, the structure of the links between psychotic experiences and social anxiety and its components and psychological parameters is analyzed. A mediator model of the relationship between social anxiety and the phase of psychotic alienation — "experiencing external control" — is discussed. AIM: To investigate the parameters and stages of development of psychotic and psychotic-like experiences registered with the Psychotic Experiences Questionnaire in the context of analyzing the structure of relationships with psychological variables (social anxiety, metacognitive and cognitive phenomena). Тo construct a mediator model of the indirect effect of social anxiety components on the “experience of being controlled externally” mediated by thought suppression (“polar bear effect”). MATERIALS AND METHODS: The sample — 122 respondents, includes non-clinical and two clinical groups — with symptoms of the affective spectrum and with symptoms of the psychotic spectrum. The author's ‘Psychotic Experiences Questionnaire’ was used to assess the severity of psychotic experiences, the scales of which represent the phases of the unfolding of the experiences. Social anxiety and its components (author's “Social Anxiety and Social Anxiety Disorder Questionnaire”), cognitive (“Cognitive Flexibility Questionnaire”, “Behavioural Self-Regulation Style — SSPM 2020” questionnaire) and metacognitive (Thought Suppression Scale, author's “Self-Focused Attention Questionnaire”) strategies were determined. RESULTS: Pearson correlation analysis showed significant ‘direct’ associations of early and moderate psychotic and psychotic-like experiences with social anxiety and its components, metacognitive (self-focused attention and thought suppression) parameters, and ‘inverse’ links with cognitive parameters (cognitive component of conscious self-regulation and cognitive flexibility). Correlations with psychological parameters become insignificant in intense psychotic experiences. Using mediator analysis, the full indirect effects of the social anxiety components influence on the enhancement of “experiencing being controlled externally” as a phase of psychotic experiences maximum intensity were measured (mediator — thought suppression). CONCLUSION: Metacognitive strategies, social anxiety, disturbed self-regulation and flexibility play an important role in the genesis and maintenance of psychotic experiences. Significant correlations of the parameters with psychotic experience are shown, but at the height of alienation the significant correlations weaken. At the height of psychotic experience in the absence of direct effects it is possible to explicate the indirect influence of the predictor — social anxiety on the experience of controllability from the outside, mediated by thought suppression. This article is a continuation of the article by Sagalakova OA, Truevtsev DV, Zhirnova OV. Psychotic Experiences Questionnaire. Part 1. Neurology Bulletin. 2024;56(1):23–36. DOI: https://doi.org/10.17816/nb623959

Sinusoidal LED light recipes can improve rocket edible biomass and reduce electricity costs in indoor growth environments.

Accumulation of edible biomass by crop plants relies on maintenance of a high photosynthetic rates across the photoperiod, with assimilation rate (A) generally responding to increasing light intensity in a hyperbolic fashion. In natural environments light fluctuates greatly over the course of the day, however in Controlled Environmental Agricultural (CEA) systems, light intensity can be supplemented or precisely controlled using LEDs to create near optimum conditions. In such indoor growth environments light is often delivered as a square wave and recommendations to horticulturalists are given in the form of Daily Light Integrals (DLI). However, this does not take into account the slow photosynthetic induction at the start of the photoperiod and the decline of A towards the end of the photoperiod, which has been demonstrated by several previous studies. Square wave light regimes therefore potentially cause suboptimal photosynthetic utilization of the applied lighting and waste electricity. Here we have adapted light recipes to gradually increase and decrease in intensity to take account of these findings. We demonstrate that, utilising a sinusoidal light regime capped at 250 μmol m-2 s-1, it is possible to increase edible biomass of rocket (by ca. 20%) compared to square wave delivered at 250 at the same DLI. Additionally, this can be achieved using less electricity (0.6%), therefore reducing energy costs and improving profitability. We suggest that capping maximum light intensity at 250 µmol m-2 s-1 improves the operating efficiency of PSII photochemistry (Fq'/Fm') also known as the photosynthetic efficiency by maintaining A later in the photoperiod. We show that a higher electron transfer rate (ETR) is maintained in these treatments over the photoperiod compared to higher light intensity caps, resulting in a greater Daily Photochemical Integral (DPI). We attribute this to less NPQ due to a greater sink capacity for the end products of electron transport, ATP and NADPH, as A is kept high for longer.

Robust online monitoring system for PCDD/Fs in a full-scale MSWI by Deans switch: Efficiently separation and purification

Existing online monitoring system for polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), technically named Thermal Desorption-Gas Chromatography-Tunable Laser Ionization-Time of Flight Mass Spectrometry (TD-GC-TLI-TOFMS), has been applied in several incinerators in China. TD-GC-TLI-TOFMS can realize rapid detection of PCDD/Fs emissions from incineration sources. However, the long-term measurement of unclean flue gas will pollute the instruments in TD-GC-TLI-TOFMS, and interfere with the peak output of the target 1,2,4-trichlorobenzene (1,2,4-TrCBz). In this study, Deans switch (DS) was utilized for the first time in an online monitoring system for PCDD/Fs to separate 1,2,4-TrCBz signal from impurity signals, which improved the anti-interference capability of the system. Laboratory standard gas experiments showed that after adding a DS device between GC and TLI pulse valve, when the pressure set in DS was 4 psi and switched before or near the peak output of 1,2,4-TrCBz, the change of 1,2,4-TrCBz signal intensity was minimal. The impurities near the target peak were removed, and TLI-TOFMS was highly stable during continuous measurement. Moreover, the maximum intensity peak time of 1,2,4-TrCBz was stable after using DS in different switching time intervals. When connecting DS to TD-GC-TLI-TOFMS for field validation on the tail flue gas of a municipal solid waste incinerator (MSWI), results showed that a better 1,2,4-TrCBz signal could be obtained with a 69.52 % reduction of impurity peaks at the moments closer to the target peak. Furthermore, DS improved the sensitivity of the system to low concentration variations of 1,2,4-TrCBz in the flue gas. The robust system developed in this study can be better applied to incineration factories with poor combustion or suboptimal purification technology, facilitating online PCDD/Fs monitoring.

Plasmonic Ag Nanoparticles: Correlating Nanofabrication and Aggregation for SERS Detection of Thiabendazole Pesticide.

The level of aggregation and aggregate morphology of metallic nanoparticles are factors that influence the SERS signal (surface-enhanced Raman scattering), affecting reproducibility and sensitivity. This study presents a systematic evaluation of the colloidal aggregation on the SERS signal by combining transmission electron microscopy and UV-vis extinction spectroscopy. It focuses on the effect of two methods of sample preparation ("external standard method-ESM" and "standard addition method-SAM") on the SERS signal using the fungicide thiabendazole (TBZ) in Ag colloid as a probe molecule. The TBZ critical concentration (concentration for which SERS reaches the maximum intensity) was 6.0 × 10-6 mol/L for ESM and 1.5 × 10-6 mol/L for SAM. Besides, TBZ exhibited a sigmoid-type isotherm for ESM, indicating formation of a TBZ first layer on Ag nanoparticles at lower concentrations (Ag aggregates more compact; size <500 nm) and TBZ multilayers at higher concentrations (Ag aggregates more branched; >2 μm). For SAM, the TBZ first layer formation was also observed at lower concentrations (Ag aggregates more branched; <2 μm). However, at higher concentrations, the Ag colloid degradation/precipitation was observed (Ag aggregates more compact; >2 μm). The Ag aggregation mechanisms align with reaction-limited colloidal aggregation at lower concentrations and diffusion-limited colloidal aggregation at higher concentrations. We believe these results contribute to the SERS research field despite all of the work already done over its 50-year history.

POE-Mediated Tunable Quantum Yield of Carbon Dots-Derived From Agapanthus Africanus (L.) Hoffmann Leaves.

The green synthesis of carbon dots (CDs) from natural sources is a challenging goal. Herein CDs are produced from Agapanthus africanus (L.) Hoffmann leaves by carbonization at 200/300 °C for 2/3h. Samples are named CZ-X-Y, where Z, X, and Y represent carbonization, temperature, and time, respectively. CZ-200-3, CZ-300-2, and CZ-300-3 CDs have average sizes of 3.7 ± 0.7, 5.3 ± 1.2, and 5.1 ± 1.6nm, respectively. Their surface, devoid of chlorophyll, contains ─OH, ─C═O, and ─C(═O)OH groups and sylvite. Isolated CZ-300-3 emits at 400nm (excited at 260nm) and exhibits an emission quantum yield (QY) value of 2 ± 1%. Embedding in the d-U(600)/d-(900) di-ureasil matrices resulted in transparent films with emission intensity maxima at 420/450nm (360nm), and QY values of 7 ± 1/16 ± 2% (400nm). The enhancement of the QY value of the bare CDs agrees withan efficient passivation provided by the hybrid host. The hydrophilic CZ-300-3 CDs also exerted a marked surface modifying role, changing the surface roughness and the wettability of the hybrid films.

Subsurface Marine Heatwaves in the South China Sea

AbstractMarine heatwaves (MHWs), extreme warm ocean temperature events, greatly impact marine ecosystems. While most MHW studies in the South China Sea (SCS) focus on the sea surface, subsurface characteristics remain less explored. This study uses high‐resolution (1/12°) ocean reanalysis data sets to assess MHW properties with depth in the SCS from 1993 to 2022. We find that MHW intensities are typically stronger at subsurface levels (30–150 m) than at the surface, with significant spatial variations. The vertical structures of MHW maximum and cumulative intensities peak between 70 and 100 m with 2.7°C and 63°C days, respectively; MHW annual days and duration increase gradually from 10 to 2,000 m with duration peaks at 2,000 m (∼60 days), four times longer than that at the surface. The SCS experienced two major periods of extensive El Niño‐related subsurface MHWs from 1997 to 2002 and 2008 to 2014, with MHWs reaching depths of 150 m and covering 70% of the upper 40 m. Strong El Niño events strengthen the western Pacific subtropical high, reducing summer monsoon winds, weakening coastal upwelling east of Vietnam, and increasing water temperatures. Regions of elevated eddy kinetic energy in the SCS suggest that significant mesoscale eddy activities are situated east of Vietnam. In addition, notable eddy heat transport was observed in the above region and west of the Luzon Strait in the upper 1,000 m. This may help to explain the high maximum and cumulative intensities of MHWs exceeding 100 m in the northern SCS.

Marangoni flow-guided molecular accumulation for sensitive and rapid SERS detection of phthalates

Public attention has been emerging for the prevention and assessment of healthcare risks from phthalate esters (PAEs) in daily life. For the effective detection of small environmentally hazardous materials, we suggest two major points: i) the formation of high-density hotspots and ii) the delivery of molecules to the activated plasmonic regions. In this study, we developed a method for laser-induced Marangoni flow in cotton fabric (CF) nanopillars (NPs) deposited with Au (Au/CFNPs) for the detection of PAEs by surface-enhanced Raman spectroscopy (SERS). We optimized the performance of the Au/CFNP platforms by adjusting both the maskless plasma etching time and the Au deposition thickness. Narrow (∼8 nm) and populated hotspots were achieved at an Ar plasma treatment time of 30 s and a Au thickness of 150 nm. The molecular behaviors were observed via real-time monitoring of SERS signals. Under continuous laser illumination, Marangoni radial convection flow became predominant over the outward capillary force, resulting in molecular accumulation in the detection areas. For small probe dyes and PAEs, the maximum intensities were achieved within 80 s after the injection of analytes and their signal fluctuations were estimated to have a relative standard deviation of < 10 %, which indicated sensitive and reproducible sensing. The prediction of PAEs extracted from the actual samples was investigated on the basis of a model used to quantitatively fit reference samples and the results were compared with those obtained by high-performance liquid chromatography. The results demonstrated that the combination of densified hotspots on three-dimensional porous substrates and laser-induced Marangoni flow is highly desirable for on-site early screening assays for low-quantity harmful materials present in surrounding environments.

High thermally stable and efficient rare-earth celsian by phase transformation of Ba2+-Exchanged SOD zeolite

The white LEDs with high performance and excellent luminous quality is of high importance for developing the current lighting industry, and high thermally stable blue phosphors play a critical role in the preparation of white LEDs. Herein, we reported a facile way to obtain highly efficient blue Eu2+-doped celsian phosphor with excellent thermal stability by a phase transformation of Ba2+-exchanged SOD Zeolite strategy. The structure of phosphors changed from nepheline to celsian with the doping of Ba2+, and the maximum emission intensity blue-shifts from 550 nm to 450 nm under the excitation of 370 nm. The PLQY is determined to be 56 %, 96 % and 82 % for the phosphor with Ba2+ doping concentration being 0, 1.49 and 1.86, respectively, and the luminescence intensity at 423 K is can be 80 %, 102 % and 93 % of its intensity at room temperature. Finally, the package of the LED device based on our yellow and blue phosphors together with the commercial red CaAlSiN3:Eu2+ phosphor is constructed to show warm white light with the CCT of 3705 K and a high CRI of 97.7. This study provides a facile way for obtaining satisfactory phosphors for high-quality lighting.

Up-conversion luminescence and multimodal temperature sensing behaviors in the visible and infrared region of Er3+ and (Er3+, Yb3+) ions in Ca3Ta2Ga3O12 phosphors

Ca3Ta2Ga3O12 - CTGG ceramic phosphors doped with xEr3+ ions, x = (0.1, 1, 3, 5, 7, and 9 at.%) and (5Er, yYb), y = (0.1, 1, 3, 5, and 7 at.%) were investigated. The emission spectra of Er3+ ions were measured under 973 nm and 1550 nm excitations and the optimal concentrations of Er3+ and (Er3+, Yb3+) ions allowing to obtain the maximum emission intensities in the visible range were determined to be 5Er and (5Er, 5Yb), respectively. The best results in terms of correlated color temperature (CCT) and color purity (CRI) were obtained under λex = 973 nm. High values of CCT (between 5000 K and 6000 K) and CRI (in the range of 80 - 92) parameters indicate their potential as efficient materials for white light-emitting diode devices. The temperature dependence of Er3+ luminescence in 5Er:CTGG and (5Er, 5Yb):CTGG samples was investigated by the luminescence intensity ratio for different thermally coupled (TCLs) and non-thermally coupled (NTCLs) levels and the fluorescence lifetime. The highest value of the relative thermal sensitivity parameter (Sr) for 5Er:CTGG sample, Sr = 1.41 % K-1 at 325 K, was obtained from TCLs (2H11/2/4S3/2) under λex = 973 nm. For (5Er, 5Yb):CTGG sample, the highest values of Sr were obtained as follows: Sr = 1.77 % K-1 at 325 K from TCLs (2H11/2/4S3/2), Sr = 1.19 % K-1 at 150 K from TCLs (4I13/2(2)/4I13/2(3)), and Sr = 0.62 % K−1 at 450 K from 4S3/2 lifetime, under λex = 973 nm, and Sr = 1.23 % K-1 at 325 K from TCLs (2H11/2/4S3/2) and Sr = 1.21 % K-1 at 325 K from NTCLs (2H11/2/4F9/2) under λex = 1550 nm. These results indicate that 5Er:CTGG and (5Er, 5Yb):CTGG ceramic phosphors have high potential for applications in the field of optical temperature sensors.

New insights into fracture and cracking simulation of quasi-brittle materials based on the NMMD model

The simulation of crack-induced failure is of vital importance for the safety and integrity assessment of solids and structures but still challenging. Being the foremost approach, fracture mechanics is plagued by the logical inconsistency in dealing with crack and non-cracked region, and to make matters worse, it has been contradicted by the ongoing experiments that the fracture energy is not a material constant irrelevant to geometry even for the unsophisticated situations. In this paper, based on the recently proposed nonlocal macro-meso-scale consistent damage (NMMD) model, it is demonstrated that the logical consistency of governing equations either on crack-tip or off crack-tip plays a crucial role in the complete solution of cracking problems. To this end, the central themes of fracture mechanics, including the definition of an idealized crack, the separated equilibrium laws and the cracking criteria attached to crack-tip, are firstly revisited. Then, after a concise description of NMMD model with emphasis on the geometrical transmission form micro- to macro-scale and the physical–mechanical translation from geometry to energy, it is theoretically proved that the geometry-based damage zone reproduces idealized crack as a limit when the nonlocal characteristic length, i.e., the influence radius in NMMD model, tends to zero. As a result, the separated equilibrium laws of fracture mechanics can be covered by NMMD model with a unified set of governing equations that does not distinguish between points at crack surface and at non-cracked region. This advantage permits NMMD model to be well-suited to analyze both crack-induced failure problems with and without pre-existing cracks in the absence of additional cracking criteria. In contrast, owing to its macro-meso-scale consistent feature, a new criterion for kinking angle of crack, the maximum stress intensity factor (SIF) of mode-I, can be derived from NMMD model. Some representative numerical examples are also presented to further confirm the above intrinsic link to fracture mechanics. In particular, the superiority of the NMMD model is demonstrated by capturing not only the non-constant fracture parameters (especially the fracture energy) but also the cracking initiation not from the pre-existing crack-tips, which are revealed by experimental results but contradict fracture mechanics. These investigations imply that the NMMD model could provide a potential avenue to understand when and how cracks nucleate and propagate based on a two-scale perspective.

Gas–liquid mixing performance of a non‐Newtonian fluid in a multiple‐impeller agitated tank

AbstractBACKGROUNDThis target is to decide power input and gas hold‐up for gas–liquid mixing aqueous CMC solutions. The analysis considers the impact by varying the impeller speed and gas flow rates in a stirred tank bioreactor of three kinds of multiple impellers. The effects of the impeller type, rheology, and operating conditions were investigated on power drawn, relative power demand (RPD), gas holdup, and volumetric mass transfer coefficient.RESULTCompared to the Rushton turbine (6RT) and 4‐pitch blade (4PBT) impeller, the propeller (3PP) impeller presented a minimal event of the gassing on the RPD. 4PBT impeller has shown a higher gas hold‐up compared to the Rushton turbine and propeller impellers. The aerated agitated tank was established a dimensionless correlation for the RPD as a function of flow number and web number. Besides, the gas–liquid agitated system was also introduced a dimensionless correlation to compute the overall gas hold‐up as a function of specific power consumption. For the maximum dispersion mixing intensity, the impeller structure with low RPD looks to be more adequate. Further, maximizing gas holdup in the structures with high RPD is advantageous. The effects of impeller speed, gas superficial velocity, and rheology on the volumetric mass transfer coefficient were examined.CONCLUSIONThe volumetric mass transfer coefficient increased with an increase in impeller speed, gas superficial velocity, and power consumption per unit volume and decreased as rheology increased. The averaged kLa for each multiple‐impeller was correlated well with the specific gassed power consumption and gas superficial velocity. © 2024 Society of Chemical Industry (SCI).

Signature of climate dynamics on hydrological drought dynamics: A qualitative analysis

Understanding the complexity of climate dynamics is of paramount importance, because climate variability and change significantly affect water cycles and ecosystems. However, recurrent hydrological droughts that have been observed every 10 years on the two primary tributaries of the Congo River (the Ubangui and Kasaï Rivers) since the advent of the 1969 drought lack a plausible explanation for variability or climate change. This study proposes a plausible explanation for recurring hydrological droughts. Given the low rate of human activity and vegetation cover evolution in the Congo Watershed, we propose that climate dynamics play a crucial role in hydrological drought dynamics. By applying the Bayesian approach to a gridded precipitation database, we obtained posterior probability maps for each annual time step during our observational period (1940–2020). This provided a spatiotemporal representation of the areas affected by climatic disturbances, unlike previous studies that were limited to a spatial representation of the temporal location of the disturbances. Our qualitative analysis of the maximum intensity of the climate disturbance signal (CPS) revealed an average cycle of 10 years and eight months of signal migration. However, we observed that every 10 years since the advent of the drought during 1969, the hydrological drought occurrence dates coincided with CPS migration dates. This highlights the influence of this cycle on the hydrological drought dynamics. Nevertheless, because of the monthly scale involved in the propagation time from meteorological to hydrological drought, the error in this cycle was considered to be the propagation time of disturbances. Therefore, we recommend that future research should focus on estimating this time to test this hypothesis. This study underscores the significance of the cyclic dynamics of lengthy transient processes in understanding hydrological drought dynamics.

Возможности метода биохемилюминисценции с модельной средой из сыворотки крови в оценке антиоксидантной активности растительного сырья

Antioxidant activity (AOA) is an important indicator of the evaluation of plant raw materials (RM), which are widely used in medicine to obtain various medicines. The use of RM at the present stage of the pharmaceutical industry development allows avoiding large-scale production of synthetic medicines, accompanied by a negative impact on the environment. For an objective assessment of AOA, it is necessary to apply methods that allow determining not only the content of the active substance, but also generally characterizing the functional activity of RM. The article presents data on the AOA of aqueous extracts from the leaves and fruits of Hippophae rhamnoides L., Aronia melanocarpa L. The determination of antioxidant activity was performed by biochemiluminiscence (BСHL) using serum from white mongrel rats as a model environment (MЕ). The evaluation criteria were the maximum intensity (Imax) and the light sum of the glow (S). The results obtained were compared with the data of the analysis of BCHL without ME, as well as with the data of alternative methods for quantifying the antioxidant potential of RM (coulometric titration, direct titration, spectrophotometry). According to the criteria for assessing the intensity of free radical oxidation (Imax) using the BCHL method without ME, it was found that aqueous extracts from the leaves and fruits of A. melanocarpa, as well as H. rhamnoides leaves, have a high antioxidant potential (343, 274 and 268 mV, respectively), and from H. rhamnoides fruits – more short. BCHL results showed that the amount of radicals in blood serum decreased upon contact with extracts from vegetable raw materials. Among the studied samples, extracts from the fruits of A. melanocarpa were characterized by the highest AOA (S=2006±137 mV·s). At the same time, according to alternative methods, they occupy an intermediate position in terms of the quantitative content of biologically active substances (BAS) with antioxidant properties. Based on the weak correlation between the data of the BСHL method and alternative methods for determining AOA, it is concluded that it is necessary to take into account the possibility of an indirect relationship between the content of BAS in RM and the effect manifested in conditions as close as possible to biological systems. The measurement of AOA by the BСHL method is actually an assessment of the function, as well as the effectiveness of BAS, and complements quantitative methods for assessing the antioxidant activity of ME.

Coastal ocean response during the unprecedented marine heatwaves in the western Mediterranean in 2022

Abstract. The western Mediterranean Sea suffered unprecedented marine heatwaves (MHWs) in 2022. This study focuses on the response of coastal ocean, which is highly vulnerable to global warming and extreme events that threaten the biodiversity, as well as goods and services that humans rely on. Using remote sensing and in situ observations, strong spatiotemporal variations in the MHW characteristics are observed in the coastal ocean over the last decade (2013–2022). In 2022, shallow-water moorings in the western Mediterranean Sea detected between 23 and 131 d of MHWs. While the highest MHW mean and maximum intensities were detected at the surface in French waters, the highest duration was observed nearshore at 17 m depth in the Balearic Islands. As thermal stress indicators for marine ecosystems, the highest cumulative intensity and total days were found at the surface at Tarragona, and MHW temperatures warmer than 28 °C were observed to last up to 58 d at Palma. Differences between datasets are also highlighted. In 2022, depending on the sub-regions, satellites underestimated or overestimated MHW duration and intensity compared with in situ measurements at the surface. In addition, daily data underestimate maxima reached during the extreme warm events up to 1.52 °C difference compared with hourly measurements. These results invite us to continue the efforts in deploying and maintaining multi-platform observing systems in both open-ocean and coastal ocean waters to better address the coastal adaptation and mitigation in the context of climate change.

A novel rhodamine B fluorescence probe for rapid identification of different amino acids by high efficiency fluorescence spectrum-mass spectrometry.

Rapid detection of amino acids plays an important role in the field of medical diagnosis. By combining Rhodamine B with triphenylamine, a novel double-response fluorescence probe (E)-4-((4-(((3',6'-bis(diethylamino)-3-oxospiro[isoindoline-1,9'-xanthen]-2-yl)imino)methyl)phenyl)(phenyl)amino)benzaldehyde (RBTPA) was prepared for rapid identification of different amino acids. Under daylight and 365 nm irradiation, it was found that the color change was most bright at pH = 3, and changed to dim at pH = 4. When pH = 3 and pH = 4, the photophysical properties of the two strong acids are very different. The maximum redshift of UV absorption light is 110nm, and the maximum fluorescence emission intensity is 4 times different. In order to further observe their binding structure analysis with different amino acids, qualitative analysis of each response structure was determined by mass spectrometry according to different molecular weights. The fluorescence probe RBTPA has two different isomers for recognition response in aldehyde group and imine group, respectively.