Concentration Limit Research Articles

The effects of Multiwalled Carbon Nanotube to the performance of a refrigeration system

By incorporating nanofluid technology and nanolubricants into compressors, the performance can be enhanced while also lowering worldwide fuel consumption and aiming at developing cleaner, more efficient energy sources and uses. The globe is being confronted with energy security issues and heating, cooling and HVAC systems highly contribute to it. Hence, it is critical to save energy and improve the efficiency of the refrigeration cycle. This study presents experimental and theoretical findings in order to investigate the effect of Polyester (POE)-oil based multiwalled Carbon Nanotube (MWCNT) nanolubricant on the Coefficient of Performance (COP) of a refrigeration system. The objectives of this study is to analyze the stability of MWCNT nanofluids, to obtain the COP of a refrigeration cycle run with pure POE oil and MWCNT nanofluids with different concentrations respectively. The experiment was conducted by preparing 0.55, 0.65 and 0.70 g/l MWCNT nanofluid by using the two step method. The most effective concentration used in the refrigeration system was referred to the one that resulted in the highest COP. It was determined from the experiment that 0.55 g/l MWCNT nanofluid resulted in a higher COP of 5.766 as compared to the other two concentrations. Besides, it showed an improvement of 34.6% in COP as compared to the COP of using pure POE oil in the refrigeration system, which was found to be 4.285. The 0.65 g/l and 0.70 g/l concentration of MWCNT resulted in a COP of 5.618 and 5.617, respectively. The compressor work was also analyzed and was found to be reduced noticeably after adding MWCNT nanoparticles. Hence it can be concluded that the increment of MWCNT concentration in nanofluids increases the COP of the refrigeration system but only up to a certain limit of concentration.

Ecotoxicological effects of personal care products on the sea urchin Echinometra lucunter

Personal care products (PCPs) are increasingly studied worldwide to understand better their ecotoxicological effects on different aquatic species. However, studies assessing their ecotoxicological effects on tropical marine aquatic organisms are still scarce. To address this information gap, this study aimed to evaluate the acute and chronic toxicity of three PCPs, methylparaben (MP), propylparaben (PP) and butylhydroxytoluene (BHT), on the tropical sea urchin Echinometra lucunter. The procedures were based on the protocols established by the US Environmental Protection Agency and the Brazilian national standard (ABNT NBR 15350). Predictive computational tools (Opera Qsar and Vega Qsar) were used to evaluate the persistence/biodegradability, bioaccumulation and mobility of PCPs. Acute exposure results showed the following ranking of toxicity: BHT (IC50 = 38.14 mg/l) > PP (IC50 = 73.20 mg/l) > MP (IC50 = 74.47 mg/l). Chronic toxicity tests indicated that BHT presented the lowest IC50 (6.85 mg/l), followed by PP (IC50 = 15.57 mg/l) and MP (IC50 = 20.09 mg/l). Additionally, in silico predictions support the findings related to the potential risks of these PCPs in aquatic ecosystems. The data obtained in this study can support future analyses of environmental risk concerning PCPs and support the establishment of concentration limits in relevant legislation.

Selective determination of an ovarian cancer biomarker at low concentrations with surface imprinted nanotube based chemosensor

In this study, an electrochemical chemosensor that utilizes a conductive polymer-based molecularly imprinted polymer (MIP) surface for rapid and reliable determination of CA125 was devised. A novel method has been applied to fabricate CA125 imprinted polypyrrole nanotubes (MI-PPy NT) via vapor deposition polymerization (VDP) as a recognition element for highly selective and sensitive determination of CA125. The chemosensor was prepared by immobilizing MI-PPy NT onto screen-printed gold electrodes (Au-SPE) and the performance of the sensor was evaluated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in terms of selectivity, sensitivity, linear dynamic concentration range (LDR) and limit of detection (LOD). The MI-PPy NT@Au-SPE sensor exhibited high sensitivity (68.57 μA per decade) to the CA125 concentration ranging from 0.1 U mL−1 to 100 U mL−1 at an LOD of 0.4 U mL−1 with a correlation coefficient of 0.9922. The developed chemosensors with their novel design combined with a facile fabrication method, prove to be promising as future state-of-the-art biosensors.

Reprocessing and Resource Utilization of Landfill Sludge—A Case Study in a Chinese Megacity

In the past, due to improper sludge treatment technology and the absence of treatment standards, some municipal sludge was simply dewatered and then sent to landfills, occupying a significant amount of land and posing a serious threat of secondary pollution. To free up land in the landfill area for the expansion of a large-scale wastewater treatment plant (WWTP) in Shanghai, in this study, we conducted comprehensive pilot research on the entire chain of landfill sludge reprocessing and resource utilization. Both the combination of polyferric silicate sulfate (PFSS) and polyetheramine (PEA) and the combination of polyaluminum silicate (PAS) and polyetheramine (PEA) were used for sludge conditioning before dewatering, resulting in dewatered sludge with approximately 60% moisture content. The combined process involved coagulation and sedimentation, flocculation, and oxidation to treat the leachate generated during dewatering. The treatment process successfully met the specified water pollutant discharge concentration limits for the leachate, with the concentration of ammonia nitrogen in the effluent as low as 15.6 mg/L. Co-incineration in a power plant and modification were applied to stabilize and harmlessly dispose of the dewatered sludge. The coal-generating system ran stably, and no obvious problems were observed in the blending process. In the modification experiment, adding 5% to 7% of the solidifying agent increased the sludge bearing ratio by 53% and 57%, respectively. This process effectively reduced levels of fecal coliforms and heavy metals in the sludge but had a less noticeable effect on organic matter content. The modified sludge proved suitable for use as backfill material in construction areas without requirements for organic matter. The results of this study provide valuable insights for a completed full-scale landfill sludge reclamation and land resource release project.

Influence of Nano-Particulate Impurities and β-glucans on the Stability of Protein-Based Formulations.

Pharmaceutical grade sugars manufactured under Current Good Manufacturing Practice (cGMP) and complied with International Pharmaceutical Excipients Council (IPEC) quality standards, also contain a significant amount of nano-particulate impurities (NPIs). This review will focus on the origin of NPIs, the mechanism of their interference with Dynamic light scattering (DLS) and endotoxin tests, filtration technology to effectively reduce the NPIs, methodologies for analytical quantification of NPIs, guidance for setting the limits of threshold concentration and the overall impact of NPIs on the therapeutic activity, performance, stability of biopharmaceuticals and protein-based formulations. NPIs with an average particle size of 100 to 200 nm are present in sugars and are a combination of various chemicals such as dextrans (with the presence of β-glucans), ash, inorganic metal salts, aromatic colorants, etc. These NPIs primarily originate from raw materials and cannot be removed during the sugar refinement process. While it is commonly believed that filtering the final formulation with a 0.22 μ sterilizing grade filter removes all microbes and particles, it is important to note that NPIs cannot be filtered using this standard sterile filtration technology. Exceeding the threshold limit of NPIs can have detrimental effects on formulations containing proteins, monoclonal Antibodies (mAbs), nucleic acids, and other biopharmaceuticals. NPIs and β-glucans have a critical impact on the functionality and therapeutic activity of biomolecules and if present below the threshold limit of reaction, stability and shelf-life of biologics formulation will be greatly improved and the risk of immunogenic reactions must be significantly decreased.

Local Rényi entropy-based Gini index for measuring and optimizing sparse time-frequency distributions

This paper introduces a novel localized Gini index (GI) designed for the assessment and optimization of time-frequency distributions (TFDs). This approach employs the localized Rényi entropy (LRE) to quantify the local number of signal components, providing a unique perspective on interpreting time and frequency slice segments while considering the presence of auto-terms or cross-terms. The results demonstrate the effectiveness of the proposed LRE-based GI in overcoming the limitations of conventional concentration and sparsity measures, particularly in scenarios with varying component numbers and missing essential components that may arise during TFD reconstruction using the compressive sensing method. Furthermore, it proves as an efficient objective function in meta-heuristic optimization, ensuring the preservation of auto-terms and a significant enhancement in overall TFD quality. The performance of the proposed LRE-based GI is demonstrated on noisy synthetic and real-life signals.

Contamination and Carcinogenic Risks of Lead in Lip Cosmetics in China.

There are growing concerns about elevated lead (Pb) levels in lip cosmetics, yet in China, the largest lip cosmetic market, recent Pb contamination in lip cosmetics and associated Pb exposure remain unclear. Here, we measured Pb levels of 29 popular lip cosmetics in China and conducted the bioaccessibility-corrected carcinogenic risk assessments and sensitivity analysis regarding Pb exposure for consumers using Monte Carlo simulation. The Pb concentrations of collected samples ranged from undetectable (< 0.05µg/kg) to 0.21mg/kg, all of which were well below the Pb concentration limit set for cosmetics in China (10mg/kg). The 50th percentile incremental lifetime cancer risk (ILCR) of Pb in Chinese cosmetics (1.20E-07) was below the acceptable level (1E-06), indicating that the application of lip cosmetics and subsequent Pb exposure does not pose carcinogenic risks to consumers in most cases. The results of this study provide new insights into understanding the Pb risk in lip cosmetics.

Radiological hazards assessment associated with granitoid rocks in Egypt

The present study aimed to assess the radioactive hazards associated with the application of granitoid rocks in building materials. An HPGe spectrometer was used to detect the levels of the radioactive elements uranium-238, thorium-232, and potassium-40 in the granitoid rocks. The results showed that the levels of these elements were lower (38.32 < 33 Bq kg−1), comparable (47.19–45 Bq kg-1) and higher (992.26 ≫> 412 Bq kg−1) than the worldwide limits for 238U, 232Th, and 40K concentration, respectively. The exposure to gamma radiation of granitoid rocks was studied by various radiological hazard variables like the absorbed dose rate (Dair), the outdoor and indoor annual effective dose (AEDout and AEDin), and excess lifetime cancer risk (ELCR). A variety of statistical methods, including Pearson correlation, principal component analysis (PCA), and hierarchical cluster analysis (HCA) was used, to study the relationship between the radioactive elements and the radiological hazards. According to statistical analysis, the main radioactive risk of granitoid rocks is contributed to by the elements uranium-238, thorium-232, and potassium-40. Granitoid rocks can be applied in building materials, but under control to prevent risk to the public.

Legal features of the joint regulation of pollutants discharge

The environmental and legal sub-institute for the regulation of pollutants discharge (RPD) from man- made point sources into the surface waters of Ukraine and its main tool - the Basin Principle for Calculating the Maximum Permissible Discharges (BPCMPD) is studied. The purpose of the article is to identify the legislative possibilities of the current Ukrainian RPD, the features of its possible use in river basin management plans (RBMP), and to assess of the legal consequences of such use. The relevance of the research is determined by documents of the state environmental policy, strategies of environmental security and of post-war reconstruction of Ukraine. BPCMPD is investigated by the method of environmental and legal analysis. It was determined that the main legal feature of the BPCMPD, which has remained unchanged for almost half a century, is the joint special water use (SWU) in the part of P discharges from economic entities within the estimated area of the water body. In modern water legislation, the category of SWU is not defined. A conceptual conflict between the object and the regulation method has been identified, which is eliminated by changing the scientifically erroneous definition of “basin” in the name BPCMPD to “cascade” name, i.e. KPCMPD. The use of the term BPCMPD is based on the division of the assimilation capacity (AC) of the cascade between the community of water users. Founded that in fact, the feature AC has an indivisible nature, which gives an ecological obstacle for the application of the BPRGDS. In addition, the current legal prohibition for the cascade use of AC is the requirement of territorial unity of regulatory limits of concentrations of AC in the receiving cascade water. Determined that the so-called “the right to AC quota”, on which the BPCMPD is based, is absent in the current legislation. Therefore, the SWU category is a legislative rudiment, and its use for the implementation of BPCMPD leaves for water users opportunities for deterioration of water quality. Concluded that the BPCMPD cannot be used as a legal instrument in the composition of Ukrainian RBMP under the conditions of SWU harmonization with EU legislation.

How does mine tailings slurry solids concentration affect stability of dam embankment slope?

ABSTRACT In view of many past failures of tailings storage facilities, practising engineers have been analysing current design guidelines for different elements of these facilities, including for tailings dams. In this paper, an attempt is made to investigate how varying tailings slurry solids concentration ( c s ) affects the stability of tailings dam embankment slope. To achieve this, elaborate two-dimensional limit equilibrium and finite element simulations were conducted and a steady-state seepage analysis was performed so as to obtain accurate free surface water flux through the slope. Initially, numerical analyses were performed for the downstream embankment slope when no material is retained upstream. Subsequently, with all parameters kept constant, the same slope was then checked when water is retained upstream, and finally for varying slurry solids concentration. Special attention was paid to the boundary between sedimentation and consolidation, defined as the solids concentration limit beyond which effective stresses start to develop. From the stability analyses performed, it is found that the factor of safety of embankment slope varies nonlinearly with total unit weight of the slurry. For coal tailings slurry, factor of safety reduced from 1.24 when water is retained to 1.15 when tailings slurry with c w = 60% is retained, representing a drop by 7.3%.

Development of high-performance biodegradable and non-toxic demulsifier for dehydration of field crude oil emulsion: Statistical design and process optimization

In this paper, a simple high-performance non-toxic, and biodegradable demulsifier was synthesized based on the ester of oleic acid and polyethylene glycol to dehydrate crude oil emulsions. Fourier transform infrared, nuclear magnetic resonance, and thermogravimetric analysis were carried out to characterize the synthesized demulsifier. The standard bottle test was carried out to investigate the demulsification performance using the synthesized demulsifier under varying process variables, including the demulsifier concentration, temperature, settling time, and water content in crude oil emulsion. Central Composite Design (CCD) based on the Response Surface Method (RSM) was employed for statistical design and process optimization to maximize the dehydration performances for finding the optimal process variables. The accuracy of the developed statistical models was evaluated using an analysis of variance. The result indicates that the demulsifier concentration, temperature, settling time, and water content have significantly influenced the response demulsification efficiency (DE). At the optimum condition, a maximum DE of 100% and viscosity reduction of 80% were achieved using a 731 ppm demulsifier concentration in 32 min of settling time with a water content of 40% at 80 °C. A more efficient method to predict DE by direct measuring the emulsion viscosity (VIS) was established in a minimal time without a bottle test. The correlation between DE and VIS was also developed to determine the DE of crude oil emulsion. Further, biodegradability and toxicity tests were performed using standard tests method and found to be biodegradable and non-toxic satisfying the environmental standard limits of percent biodegradability and lethal concentration (LC50).

Direct determination of high-concentration As(III) by UV high-reference differential absorption spectroscopy for cleaner As(III) removal promotion via sulfurization

The current methods for determining high-concentration As(III) in the high-acid matrix from the copper smelting industry are complex, time-consuming, and costly. This limits effective modulation of sulfurizing agent dosage for As(III) removal via sulfurization, aggravating hazardous waste generation. Herein, a simple, rapid, and nondestructive UV high-reference differential absorption spectroscopy was developed to directly determine high-concentration As(III) in simulated high-acid wastewater. Time-dependent density functional theory calculations indicated that the spectral curve redshift with As(III) concentration increasing was related to the decrease of electron transition energies and energy gaps. When using high-reference solutions, the least redshift in the maximum absorption wavelength and the highest upper limit of linear fitting concentration could be obtained. Therefore, the piecewise quantitative linear model of differential absorbance and concentration was established under high-reference. The quantitative range of the model within 0.06–20.00 g/L As(III) with a mean relative error of < 5.0 % and standard recovery rates within 98.0 %-104.0 % indicated high accuracy. Additionally, the relative standard deviations of < 1.5 % (n = 5) revealed good precision. All results indicated the high feasibility of the developed method in alleviating linear deviation caused by redshift and absorption saturation. Furthermore, it has potential significance in saving sulfurizing agent dosage and reducing hazardous waste generation from the source, thereby facilitating a cleaner process for removing As(III) via sulfurization.

Defective MoSSe with local-expanded structure for high-rate potassium ion battery

Potassium ion batteries with microparticulate electrodes promise a high volumetric capacity, yet they suffer from poor rate capacity and cyclic stability due to the long K+diffusion path and structural collapse upon K+ insertion/de-insertion. In this work, a local-expanded MoSSe material with wave structure is successfully constructed in a microparticulate state (labeled as LE-MoSSe). The high curvature design in this wave structure breaks the defect concentration limitation in MoSSe crystal, resulting in an abundance of surface active site with up to 29 % vacancy defects for S and 31 % for Se. Moreover, such a structure can adaptively and efficiently release internal stress during long-term repeated K+ insertion/de-insertion. Consequently, the LE-MoSSe material delivers a superior volumetric capacity (854 mAh cm−3), a record-high rate capability (19.3 C, ∼3 min), and a long cycle stability (only 0.039 % fading per cycle). This work demonstrates a practical approach to accelerate reaction kinetics and enhance structural stability of TMDs toward practical battery systems.

Stabilization of heavy metals in municipal solid waste incineration fly ash using organic chelating agents: Insight into risk assessment and function mechanism

Landfill treatment of municipal solid waste incineration fly ash (MSWI FA) after stabilization is the primary disposal technology. However, only few studies have assessed the stability of MSWI-FA-chelated products in different landfill scenarios. In this study, three commonly used dithiocarbamate (DTC)-based organic chelating agents (CAs) (TS-300, SDD, and PD) were selected to stabilize heavy metals (HMs) in MSWI FA. In addition, the leaching toxicity and environmental risks of the chelated products were assessed in different disposal environments. The results demonstrate that the HM leaching concentrations of the chelated products met the concentration limits of the sanitary landfill standard (GB16889–2008; mixed Landfill Scenario) for the three CAs at a low additive level (0.3 %). However, in the compartmentalized landfill scenario (the leaching agent was acid rain), the leaching of HMs from the chelated products met the standard when TS-300, SDD, and PD were added at 1.5 %, 6.0 %, and 8.0 %, respectively. Additionally, Pb, Zn, and Cd in the chelated products from the 1.5 %-TS-300 and 6.0 %-SDD groups met the leaching limits within the pH ranges 6–12 and 7–12, 6–12 and 7–12, and 8–12 and 8–12, respectively. This was primarily due of TS-300's multiple DTC groups forming stable chain-like macromolecular chelates with Pb. However, although the environmental risks associated with Pb, Zn, and Cd in the initial (0-d) chelated products of the 1.5 %-TS-300 and 6.0 %-SDD groups were minimized to low and negligible levels, there was a significant increase in the leaching of the three HMs after 28 d of storage. Therefore, with appropriate CA addition, although the leaching concentration of HMs in the chelated product may comply with the GB16889–2008 standards, it remains essential to consider its environmental risk, particularly in highly acidic or alkaline environments and during prolonged storage of the product.

Enhancing luminescence, tuning emission colors, and improving temperature sensitivity in NaGd(MoO4)2 multilayer thin films

A thin film with a sandwich structure of NaGd(MoO4)2: Yb3+@Yb3+/Ho3+@Yb3+ was successfully prepared using the spin-coating method. A comparative analysis of this sandwich-structured film with other films having the same doping composition and spin coating times showed that the emission intensity of the former was enhanced. We attribute the luminescence enhancement of the sandwich-structured film to the presence of Yb3+ ions in both the top and bottom layers. This overcomes the concentration quenching effect imposed by the Yb3+/Ho3+ system's concentration limit. Moreover, the warm white light emission of the NaGd(MoO4)2:Yb3+@Yb3+/Tm3+@Yb3+/Ho3+@Yb3+ film was successfully achieved by introducing Yb3+/Tm3+ layers, and tuning from blue to white to yellow was realized by adjusting the number of spin coatings and the proportion of Yb3+/Tm3+ and Yb3+/Ho3+ layers. Finally, we found that sandwich-structured films have better temperature sensitivity compared to powder materials and other structured films. These results indicate that rare-earth doped NaGd(MoO4)2 thin films have great potential in the fields of luminescence, color display, and temperature sensing. The adjustment of luminescence color can be achieved by manipulating the micro/nano film structure, and the spin-coating process can effectively improve the temperature sensing characteristics.

Remote Sensing Model for Estimating Atmospheric PM2.5 Concentration in the Guangdong-Hong Kong-Macao Greater Bay Area

PM2.5 is extremely harmful to the atmospheric environment and human health, and a timely and accurate understanding of PM2.5 with high spatial and temporal resolution plays an important role in the prevention and control of air pollution. Based on multi-angle implementation of atmospheric correction algorithm (MAIAC), 1 km AOD products, ERA5 meteorological data, and pollutant concentrations (CO, O3, NO2, SO2, PM10, and PM2.5) in the Guangdong-Hong Kong-Macao Greater Bay Area during 2015-2020, a geographically and temporally weighted regression model (GTWR), BP neural network model (BPNN), support vector machine regression model (SVR), and random forest model (RF) were established, respectively, to estimate PM2.5 concentration. The results showed that the estimation ability of the RF model was better than that of the BPNN, SVR, and GTWR models. The correlation coefficients of the BPNN, SVR, GTWR, and RF models were 0.922, 0.920, 0.934, and 0.981, respectively. The RMSE values were 7.192, 7.101, 6.385, and 3.670 μg·m-3. The MAE values were 5.482, 5.450, 4.849, and 2.323 μg·m-3, respectively. The RF model had the best effect during winter, followed by that during summer, and again during spring and autumn, with correlation coefficients above 0.976 in the prediction of different seasons. The RF model could be used to predict the PM2.5 concentration in the Greater Bay Area. In terms of time, the daily ρ(PM2.5) of cities in the Greater Bay Area showed a trend of "decreasing first and then increasing" in 2021, with the highest values ranging from 65.550 μg·m-3 to 112.780 μg·m-3 and the lowest values ranging from 5.000 μg·m-3 to 7.899 μg·m-3. The monthly average concentration showed a U-shaped distribution, and the concentration began to decrease in January and gradually increased after reaching a trough in June. Seasonally, it was characterized by the highest concentration during winter, the lowest during summer, and the transition during spring and autumn. The annual average ρ(PM2.5) of the Greater Bay Area was 28.868 μg·m-3, which was lower than the secondary concentration limit. Spatially, there was a "northwest to southeast" decreasing distribution of PM2.5 in 2021, and the high-pollution areas clustered in the central part of the Greater Bay Area, represented by Foshan. Low concentration areas were mainly distributed in the eastern part of Huizhou, Hong Kong, Macao, Zhuhai, and other coastal areas. The spatial distribution of PM2.5 in different seasons also showed heterogeneity and regionality. The RF model estimated the PM2.5 concentration with high accuracy, which provides a scientific basis for the health risk assessment associated with PM2.5 pollution in the Greater Bay Area.

The effect of Ficoll 70 on thermally-induced and chemically-induced conformational transitions of an RTX protein is quantitatively accounted for by a unified excluded volume model.

A unified excluded volume model based upon the effective hard particle approximation is developed and used to quantitatively model previously published experimental measurements of the effect of adding high concentrations of an "inert" polymer, Ficoll 70, on conformational transitions of the toxin protein RCL that are induced by addition of calcium at constant temperature or by increasing temperature in the absence and presence of high calcium concentrations. The best-fit of this model, which accounts quantitatively for all of the published data to within experimental precision, yields an estimate of the volume of solution excluded to Ficoll by each of four identified conformational states of RCL: H - the most compact conformation adopted in the limits of high calcium concentration and low temperature, H* - the conformation adopted in the limits of high calcium concentration and high temperature, A - the conformation adopted in the limits of low (or no) calcium at low temperature, and A* - the conformation adopted in the limits of low calcium and high temperature. Ficoll exclusion volumes increase in the order H < H* < A < A*. These results are discussed in the context of the physiological functions of the RTX proteins, which are involved in the secretion process and the calcium-induced folding of bacterial virulence factors.

Efficacy and tolerability of Profhilo® Structura intended to restore lateral cheek fat compartment: An observational pilot study.

Hyaluronic acid (HA)-based injections are used worldwide to improve skin defects associated with aging and ultraviolet light/environmental exposure. HA formulations developed according to molecular weight or with additional components, for example, cross-linking reagents, are limited by their low biological activity and concentration limit. NAHYCO™ technology has enabled the production of hybrid cooperative complexes (HCCs) of low and high molecular weight HA. Developed for injection into the fat compartments of the face and previously demonstrating potential benefits for adipose tissue restoration, Profhilo Structura® is a new 2 mL HCC formulation comprising low molecular weight HA (45 mg/mL) and high molecular weight HA (45 mg/mL). To evaluate the efficacy and tolerability of Profhilo Structura® to restore adipose tissue compartments in the lateral cheek fat compartment. Fifty healthy enrolled subjects received two injections, 1 month apart, and were evaluated 3 months posttreatment. Investigators performed clinical evaluations (Facial Volume Loss Scale [FVLS] and Wrinkle Severity Rating Scale [WSRS]) at different time points. Subjects also completed self-evaluation assessments following treatment. A significant improvement in FVLS and WSRS clinical scores after the first treatment was observed; treatment benefit was maintained 3 months after treatment completion and confirmed by subject self-assessment. Most participants reported an improvement, particularly a marked reduction of wrinkles and increased skin firmness. No serious adverse events were reported, confirming the excellent safety profile of HCC injectable devices. Overall, the study highlighted the efficacy and tolerability of the studied medical device proving its effect on adipose tissue.

The sub-MIC selective window decreases along the digestive tract: determination of the minimal selective concentration of oxytetracycline in sterilised intestinal contents.

The administration of antibiotics can expose the digestive microbiota of humans and animals to sub-inhibitory concentrations, potentially favouring the selection of resistant bacteria. The minimal selective concentration (MSC) is a key indicator to understand this process. The MSC is defined as the lowest concentration of an antibiotic that promotes the growth of a resistant strain over a susceptible isogenic strain. It represents the lower limit of the sub-minimal inhibitory concentration (MIC) selective window, where resistant mutants can be selected. Previous studies focused on determining the MSC under standard culture conditions, whereas our research aimed to determine the MSC in a model that approximates in vivo conditions. We investigated the MSC of oxytetracycline (OTC) in Mueller-Hinton broth (MHB) and sterilised intestinal contents (SIC) from the jejunum, caecum and rectum (faeces) of pigs, using two isogenic strains of Escherichia coli (one susceptible and one resistant to OTC). Additionally, the MIC of OTC against the susceptible strain was determined to assess the upper limit of the sub-MIC selective window. Our study took a novel approach, and the results indicated that MIC and MSC values were lower in MHB than in SIC. In the latter, these values varied depending on the intestinal segment, with distal compartments exhibiting higher MIC and MSC values. Moreover, the sub-MIC selective window of OTC in SIC narrowed from the jejunum to the rectum, with a significantly closer MSC to MIC in faecal SIC. The results suggest that OTC binds to digestive contents, reducing the fraction of free OTC. However, binding alone does not fully explain our results, and interactions between bacteria and intestinal contents may play a role. Furthermore, our findings provide initial estimates of low concentrations facilitating resistance selection in the gut. Finally, this research enhances the understanding of antimicrobial resistance selection, emphasising the intricate interplay between antibiotics and intestinal content composition in assessing the risk of resistance development in the gut.

Modified spectrophotometry for micromolar H2O2 determination in iron-containing solutions with leuco crystal violet under both aerobic and anaerobic conditions.

Accurately quantifying hydrogen peroxide (H2O2) is essential for elucidating its role across diverse environments. Spectrophotometry is widely employed in laboratories for this purpose due to its convenience, cost-effectiveness, and low detection limits for micromolar H2O2 concentrations. However, accurate measurement of H2O2 in iron-containing solutions presents challenges due to the interference of iron ions. In this study, we propose a modified spectrophotometric method for H2O2 determination in iron-containing solutions by adding two types of iron ion chelators and selecting leuco crystal violet (LCV) as a chromogenic reagent due to its stability. By sequentially adding 1,10-phenanthroline and EDTA, and using a phosphate buffer at pH 4.2 to provide the optimal chromogenic pH condition, this modified method effectively mitigates the interference of iron ions in the LCV chromogenic reaction. The applicability of this method under aerobic and anaerobic conditions was confirmed by comparing the experimental results with theoretical simulations. Under optimal chromogenic conditions, this method achieves a detection limit of 300 nM. This improved method allows better detection of H2O2 in iron-containing systems and investigation of its significance in various environmental processes.