Drop In Concentration Research Articles

Effects of double diffusion and induced magnetic field on convective flow of a Casson nanofluid over a stretching surface

Magnetohydrodynamic (MHD) flows have several applications in a wide area of engineering such as industrialized processes, including generating MHD electrical power, processing of magnetic materials, etc. The present examination focuses on incorporating the induced magnetic field (IMF) and multiple slips on the convective MHD Casson nanofluid flow over an elongating sheet with Brownian motion and thermophoresis effects. Heat source/sink, non-linear radiation, and suction/injection impacts are added to strengthen the study. The governing equations are framed with the above assumptions and converted from PDE to ODE using a suitable transformation. The MATLAB solver “bvp5c” is engaged to solve the governing equations and the results are depicted through graphs and tables. Moreover, a good agreement is found while comparing these results with pre-existing results. It is established that an increase in the Casson fluid parameter diminishes the fluid's velocity. Also, the induced magnetic field plays a vital role in decreasing the speed of the fluid. Further, with an increase in the double-diffusive parameters, the temperature rises. As the chemical process and Schmidt number parameter elevate, the concentration drops. The convective parameter and the velocity slip parameter both enhance skin friction. The Nusselt number rises when the Prandtl number gets larger. This investigation makes major contributions to reactor safety devices, crystal growth in liquids, chemical-catalyzed reactors, geophysics, solar technology, etc.

Characterizing Diffusion from Microdialysis Catheters in the Human Brain: A Magnetic Resonance Imaging Study With Gadobutrol.

Cerebral microdialysis (CMD) catheters allow continuous monitoring of patients' cerebral metabolism in severe traumatic brain injury (TBI). The catheters consist of a terminal semi-permeable membrane that is inserted into the brain's interstitium to allow perfusion fluid to equalize with the surrounding cerebral extracellular environment before being recovered through a central non-porous channel. However, it is unclear how far recovered fluid and suspended metabolites have diffused from within the brain, and therefore what volume or region of brain tissue the analyses of metabolism represent. We assessed diffusion of the small magnetic resonance (MR)-detectible molecule gadobutrol from microdialysis catheters in six subjects (complete data five subjects, incomplete data one subject) who had sustained a severe TBI. Diffusion pattern and distance in cerebral white matter were assessed using T1 (time for MR spin-lattice relaxation) maps at 1 mm isotropic resolution in a 3 Tesla MR scanner. Gadobutrol at 10 mmol/L diffused from cerebral microdialysis catheters in a uniform spheroidal (ellipsoid of revolution) pattern around the catheters' semipermeable membranes, and across gray matter-white matter boundaries. Evidence of gadobutrol diffusion was found up to a mean of 13.4 ± 0.5 mm (mean ± standard deviation [SD]) from catheters, but with a steep concentration drop off so that ≤50% of maximum concentration was achieved at ∼4 mm, and ≤10% of maximum was found beyond ∼7 mm from the catheters. There was little variation between subjects. The relaxivity of gadobutrol in human cerebral white matter was estimated to be 1.61 ± 0.38 L.mmol-1sec-1 (mean ± SD); assuming gadobutrol remained extracellular thereby occupying 20% of total tissue volume (interstitium), and concentration equilibrium with perfusion fluid was achieved immediately adjacent to catheters after 24 h of perfusion. No statistically significant change was found in the concentration of the extracellular metabolites glucose, lactate, pyruvate, nor the lactate/pyruvate ratio during gadobutrol perfusion when compared with period of baseline microdialysis perfusion. Cerebral microdialysis allows continuous monitoring of regional cerebral metabolism-the volume of which is now clearer from this study. It also has the potential to deliver small molecule therapies to focal pathologies of the human brain. This study provides a platform for future development of new catheters optimally designed to treat such conditions.

Simulating Gas-Solid Phase Isomerization of C8 Aromatics Affected by Catalyst Shapes in Fixed Bed Reactors with Particle-Resolved CFD Approach

Paraxylene (PX) is essential for producing polyethylene terephthalate fibers. We conduct particle-resolved CFD simulations, coupled with our reaction kinetics, on a fixed bed reactor randomly filled with catalyst shapes including sphere, cylinder, trilobe and quadrilobe to enlarge PX productivity in the catalytic isomerization of C8 aromatics. Our findings reveal the effects of catalyst shapes on velocity, concentration, temperature fields, and pressure drop. Although all catalyst shapes present particle utilization above 70 %, trilobes and quadrilobes show superior PX yield and ethylbenzene conversion due to their larger surface area and reduced mass transfer distance. Yet, among these catalysts, trilobes have twice the pressure drop of the others for complex geometric surface. Therefore, quadrilobes are more practical as their higher bed voidage, smaller pressure drop, better reactivity for desired reactions, and lower adiabatic temperature rise. This work provides guidance for catalyst design and process optimization to enhance PX productivity in aromatic isomerization.

A comparative study on eDNA-based detection of Siamese bat catfish (Oreoglanissiamensis) in wet and dry conditions

The use of environmental DNA (eDNA) analysis has demonstrated notable efficacy in detecting the existence of freshwater species, including those that are endangered or uncommon. This application holds significant potential for enhancing environmental monitoring and management efforts. However, the efficacy of eDNA-based detection relies on several factors. In this study, we assessed the impact of rainfall on the detection of eDNA for the Siamese bat catfish (Oreoglanis siamensis). Quantitative polymerase chain reaction (qPCR) analysis indicated that samples from days with average rainfall exceeding 35 mm (classified as heavy and very heavy rain) yielded negative results. While eDNA detection remains feasible on light or moderate rainy days, a noteworthy reduction in eDNA concentration and qPCR-positive likelihood was observed. Analysis across 12 sampling sites established a statistically significant negative relationship (p < 0.001) between eDNA detection and rainfall. Specifically, for each 1 mm increase in rainfall, there was an observed drop in eDNA concentration of 0.19 copies/mL (±0.14). The findings of this study provide definitive evidence that precipitation has a significant impact on the detection of eDNA in Siamese bat catfish. However, in the case of adverse weather conditions occurring on the day of sampling, our research indicates that it is acceptable to continue with the task, as long as the rainfall is not heavy or very heavy. To enhance the effectiveness of an eDNA survey, it is crucial to consider many factors related to climatic conditions. The aforementioned factor holds significant importance not only for the specific species under scrutiny but also for the broader dynamics of the climate.

High Decibels as Causing Deconcentration and Hearing Damage in Pilots, Crew Members and Passengers Passengers: Experimental Study in the Brazilian Air Force

Hearing is one of the main senses for aeronautical activities and plays a key role in the intelligibility of communications between pilots. Noise is a factor that impairs good hearing and can lead to various health problems, as well as impairing the performance of aviation cadets when they perform multiple tasks during flight. It is important to educate airmen about how noise can negatively affect instructional flights and the conditions that expose them to too much of a drop in concentration during flights. The sound pressure levels to which cadet airmen are exposed during their training is an aggravating factor for their communication and safety. The aim of this study was to determine whether there is a relationship between noise and loss of concentration during instruction in the Neiva T-25 aircraft, with the aim of collecting and analyzing data in order to improve air mission instruction in terms of health and flight safety by highlighting the harmful nature of noise in the Second Air Instruction Squadron (2º EIA). A questionnaire with eight questions about the influence of noise on the performance of aerial mission practices was administered to a sample of 20 Cadet Aviators from the Second Squadron who were taking part in the aerial instruction course in the Neiva T-25. The results of the questionnaires showed the importance of raising awareness about the harmful effects of noise in military activity, as it is a matter of flight safety.

Thermodiffusive desalination

Desalination could solve the grand challenge of water scarcity, but materials-based and conventional thermal desalination methods generally suffer from scaling, fouling and materials degradation. Here, we propose and assess thermodiffusive desalination (TDD), a method that operates entirely in the liquid phase and notably excludes evaporation, freezing, membranes, or ion-adsorbing materials. Thermodiffusion is the migration of species under a temperature gradient and can be driven by thermal energy ubiquitous in the environment. Experimentally, a 450 ppm concentration drop was achieved by thermodiffusive separation when passing a NaCl/H2O solution through a single channel. This was further increased through re-circulation as a proof of concept for TDD. We also demonstrate via molecular dynamics and experiments that TDD in multi-component seawater is more amenable than in binary NaCl/H2O solutions. Numerically, we show that a scalable cascaded channel structure can further amplify thermodiffusive separation, achieving a concentration drop of 25000 ppm with a recovery rate of 10%. The minimum electric power consumption in this setup can be as low as 3 Whe m−3, which is only 1% of the theoretical minimum energy for desalination. TDD has potential in areas with abundant thermal energy but limited electrical power resources and can contribute to alleviating global freshwater scarcity.

Seasonal Variation in Vertical Structure for Stratiform Rain at Mêdog Site in Southeastern Tibetan Plateau

Mêdog is located at the entrance of the water vapor channel of the Yarlung Tsangpo Great Canyon on the southeastern Tibetan Plateau (TP). In this study, the seasonal variation in the microphysical vertical structure of stratiform precipitation at the Mêdog site in 2022 was investigated using micro rain radar (MRR) observations, as there is a lack of similar studies in this region. The average melting layer height is the lowest in February, after which it gradually increases, reaches its peak in August, and then gradually decreases. For lower rain categories, the vertical distribution of small drops remains uniform in winter below the melting layer. The medium-sized drops show slight increases, leading to negative gradients in the microphysical profiles. Slight or evident decreases in concentrations of small drops are observed with decreasing height in the premonsoon, monsoon, and postmonsoon seasons, likely due to significant evaporation. The radar reflectivity, rain rate, and liquid water content profiles decrease with decreasing height according to the decrease in concentrations of small drops. With increasing rain rate, the drop size distribution (DSD) displays significant variations in winter, and the fall velocity decreases rapidly with decreasing height. In the premonsoon, monsoon, and postmonsoon seasons, the concentrations of large drops significantly decrease below the melting layer because of the breakup mechanism, leading to the decreases in the fall velocity profiles with decreasing height during these seasons. Raindrops with sizes ranging from 0.3–0.5 mm are predominant in terms of the total drop number concentration in all seasons. Precipitation in winter and postmonsoon seasons is mainly characterized by small raindrops, while that in premonsoon and monsoon seasons mainly comprises medium-sized raindrops. Understanding the seasonal variation in the vertical structure of precipitation in Mêdog will improve the radar quantitative estimation and the use of microphysical parameterization schemes in numerical weather forecast models over the TP.

Indium partitioning between silicate melts and magmatic fluids: implications for indium ore genesis and the tracing of magma degassing

Most of the global indium resources are from deposits associated with felsic rocks. Considering that the indium concentration in the average upper crust is extremely low, magmatic-hydrothermal processes play a critical role in the enrichment and mineralization of indium. However, the extraction efficiency of indium by magmatic fluids remains unclear. We performed experiments at 800 °C, 150 MPa and oxygen fugacity of Ni-NiO buffer to determine the partition coefficient of indium between aqueous fluids and granitic melts (DInf/m). To counteract the rapid loss of indium into the noble metal container wall, the DInf/m were obtained by the method of local equilibrium between microscopic-sized fluid bubbles and surrounding silicate melt. The results show that indium has the highest fluid-melt partition coefficients of all metals investigated so far. At a constant aluminum saturation index (ASI = 1.07–1.12), DInf/m correlates linearly with the total Cl concentration in the coexisting fluid (mCltotal), increasing from 61 ± 11 (1σ) at mCltotal = 1.0 mol/kg H2O to 895 ± 105 (1σ) at mCltotal = 16 mol/kg H2O. When the HCl concentration in the solution increases from 0.13 to 0.49 mol/kg H2O at a fixed mCltotal = 2 mol/kg H2O, DInf/m increases parabolically from 129 ± 21 to 320 ± 24. The observed partitioning data suggest that indium was dominantly present as In(OH)2Cl in the low-HCl and In(OH)Cl2 in high-HCl aqueous fluid at the experimental conditions. Numerical modeling indicates that the extraction efficiency of indium from S-type felsic magmas is very high (>85 %) and magmatic fluids may be the major source of indium for most indium deposits. Due to the high DInf/m values, fluid saturation and exsolution result in a sharp drop of indium concentration in both the residual melt and crystallized minerals, which makes the indium concentration in whole rock and minerals an indicator of fluid exsolution.

Validation of a Novel Noninvasive Technology to Estimate Blood Oxygen Saturation Using Green Light: Observational Study

Background Pulse oximeters work within the red-infrared wavelengths. Therefore, these oximeters produce erratic results in dark-skinned subjects and in subjects with cold extremities. Pulse oximetry is routinely performed in patients with fever; however, an elevation in body temperature decreases the affinity of hemoglobin for oxygen, causing a drop in oxygen saturation or oxyhemoglobin concentrations. Objective We aimed to determine whether our new investigational device, the Shani device or SH1 (US Patent 11191460), detects a drop in oxygen saturation or a decrease in oxyhemoglobin concentrations. Methods An observational study (phase 1) was performed in two separate groups to validate measurements of hemoglobin and oxygen concentrations, including 39 participants recruited among current university students and staff aged 20-40 years. All volunteers completed baseline readings using the SH1 device and the commercially available Food and Drug Administration–approved pulse oximeter Masimo. SH1 uses two light-emitting diodes in which the emitted wavelengths match with absorption peaks of oxyhemoglobin (hemoglobin combined with oxygen) and deoxyhemoglobin (hemoglobin without oxygen or reduced hemoglobin). Total hemoglobin was calculated as the sum of oxyhemoglobin and deoxyhemoglobin. Subsequently, 16 subjects completed the “heat jacket study” and the others completed the “blood donation study.” Masimo was consistently used on the finger for comparison. The melanin level was accounted for using the von Luschan skin color scale (VLS) and a specifically designed algorithm. We here focus on the results of the heat jacket study, in which the subject wore a double-layered heated jacket and pair of trousers including a network of polythene tubules along with an inlet and outlet. Warm water was circulated to increase the body temperature by 0.5-0.8 °C above the baseline body temperature. We expected a slight drop in oxyhemoglobin concentrations in the heating phase at the tissue level. Results The mean age of the participants was 24.1 (SD 0.8) years. The skin tone varied from 12 to 36 on the VLS, representing a uniform distribution with one-third of the participants having fair skin, brown skin, and dark skin, respectively. Using a specific algorithm and software, the reflection ratio for oxyhemoglobin was displayed on the screen of the device along with direct hemoglobin values. The SH1 device picked up more minor changes in oxyhemoglobin levels after a change in body temperature compared to the pulse oximeter, with a maximum drop in oxyhemoglobin concentration detected of 6.5% and 2.54%, respectively. Conclusions Our new investigational device SH1 measures oxygen saturation at the tissue level by reflectance spectroscopy using green wavelengths. This device fared well regardless of skin color. This device can thus eliminate racial disparity in these key biomarker assessments. Moreover, since the light is shone on the wrist, SH1 can be readily miniaturized into a wearable device.

Effect of quercetin on some biochemical parameters in adult rats treated with sodium nitrite

Sodium nitrite and quercetin are frequently employed as protective agents on glucose levels, levels of thyroid hormones, and lipid profile. The present study aimed to see the quercetin effect on some biochemical parameters in adult rats treated with sodium nitrite. A total of twenty-one laboratory animals (Wistar albino rats) were used in this experiment, separated into three groups of seven animals each. During the trial, Group I was given water only to drink and Group II received sodium nitrite directly by oral feeding needle. The study used 80 mg.kg-1/body weight (BW) of sodium nitrite, while Group IIIreceived drinking water containing sodium nitrite orally in doses of up to 80 mg.kg-1 BW and quercetin with a (50 mg/kg ). After blood was drawn and serum extracted, the parameters determined were thyroid hormones, lipids, Homeostasis Model Evaluation for Insulin Resistance (HOMA-IR) and glucose level. The study observed that compared to the controls, the insulin (HOMA-IR) and sugar levels and lipid profile of the sodium-nitrite treated group were much higher. The sodium nitrite-treated group also had a substantial drop in thyroid hormone concentrations and a rise in Thyroid Stimulated Hormone (TSH), whereas the quercetin alleviated the harmful effects of sodium nitrate by lowering blood sugar, insulin, HOMA-IR,and improved the lipid profile. There was an improvement in glucose, insulin resistance, lipidemia, and TSH hormone levels, which increased as a result of exposure to nitrite. Thus, the present study demonstrated how quercetin protected against sodium nitrite-induced toxicity by improving several biochemical parameters in adult rats.

True volumetric counting of CD34+ cells using flow cytometry

While the single-platform flow cytometric CD34+ cell counting method is the preferred choice to predict the yield of mobilized peripheral blood stem cells, most flow cytometers lack the ability of hematology counter analyzers to perform volumetric counting. However, one of the problems using reference microbeads is the vanishing counting bead phenomenon. This phenomenon results in a drop in microbeads concentration and reduces the total and relative number of beads in calibration procedures. In the last years, flow cytometers including a volumetric system to quantify cells have been developed and may represent a promising alternative to enumerate CD34+ cells avoiding the use of beads.In this study we have used a direct true volumetric counting of CD34+ cells under continuous flow pump to overcome potential drawbacks with impact in rare cell analysis. To confirm this hypothesis, we have compared the results of CD34+ cell enumeration using non-volumetric vs. volumetric systems with FC500 (Beckman Coulter) and Attune NxT (ThermoFisher) flow cytometers, respectively, in mobilized peripheral blood samples.No statistically significant differences were observed between measurements of CD34+ cells using beads, when the FC500 and Attune NxT absolute counting values were compared, or when CD34+ counts were compared on the Attune NxT, either using or not using beads. Linear regressions to study the relationship between volumetric and non-volumetric CD34+ counts confirmed the accuracy of each method. Bland-Altman test showed agreement between both methods.Our data showed that CD34+ cell enumeration using a volumetric system is comparable with current counting systems. This method represents an alternative with the advantage of the simplification of sample preparation and the reduction of the analysis subjectivity.

A sustainable process for electrochemical production of 2-Iodosylbenzoic acid

Herein, an environmentally friendly, scalable and highly efficient process for production of 2-iodosylbenzoic acid, a well-established hypervalent iodine oxidant is reported. It is based on anodic oxidation of 2-iodobenzoic acid in anhydrous AcONa-AcOH electrolyte followed by simple work-up of solid product. In particular, a benefit of the developed electrochemical process is absence of any chemical oxidant, application of environmentally benign solvent, high Faradaic efficiency and product yield. The process on the anode side combines anodic oxidation of reactant to the desired product with separation process, i.e. removal of Na+ cation from the anolyte through a cation-exchange membrane leading to drop of AcONa concentration. Consequently, the product of high purity can be obtained simply by filtering the anolyte solution followed by drying the filtration cake. Interestingly, no washing by organic solvents is required. Moreover, both anolyte filtrate and catholyte can be reused multiple times. Energy and material balance and cost and environmental footprint analysis showed benefits of the developed process and suggested clear strategy towards further reduction of the product cost and, in particular, significant decrease of a generated waste amount.

Laboratory features of effects of peloidotherapy and aromatherapy in patients with rheumatoid arthritis.

Peloidotherapy and aromatherapy have been used for years in the treatment of numerous inflammatory conditions, including rheumatoid arthritis (RA). The exact mechanism of their action in RA is unclear. The goal of our research is to determine the effect of peloidotherapy and aromatherapy on inflammation parameters in RA patients. Our study included 20 patients of both sexes, with confirmed diagnosis of RA, older than 18years. Patients were treated during 28days with combination of peloidotherapy and aromatherapy. Serum samples for detection of levels of inflammation parameters were taken at two intervals: before the start of therapy and at the end of treatment. The results of our study show that there were no significant changes in the parameters of the complete blood count. Nevertheless, a statistically significant decrease in the serum concentration of two markers of inflammation-interleukin-6 (IL-6) and nitrogen-oxide (NO)-was detected. Correlation analyses results say that there is a synchronized drop in the serum concentrations of CRP and the sedimentation rate, and the serum concentrations of fibrinogen and IL-6 are in the same relationship as well as serum levels of IL-6 and NO. Bearing in mind the importance of IL-6 and NO in the pathogenesis of inflammation in RA, we conclude that the application of our therapeutic protocol can be a significant add-on treatment to classic immunomodulators. Due to the small number of study participants, the lack of a control group, and the short follow-up time of patients, additional research is needed.

Laser-machined two-stage nozzle optimised for laser wakefield acceleration

In this paper, the modelling and manufacturing of a two-stage supersonic gas jet nozzle enabling the formation of adaptive plasma concentration profiles for injection and acceleration of electrons using few-cycle laser beams are presented. The stages are modelled using the rhoSimpleFoam algorithm of the OpenFOAM computational fluid dynamics software. The first 200–300 ${\rm \mu}$ m diameter nozzle stage is dedicated to 1 % N2 + He gas jet formation and electron injection. By varying the pressure between the first and second stages of the injectors, the electron injection location could be adjusted, and the maximum acceleration distance could be ensured. By changing the concentration of the nitrogen in the gas mixture, the charge of the accelerated electrons could be controlled. The second nozzle stage is designed for acceleration in fully ionised He or hydrogen gas and forms the optimal plasma concentration for bubble formation depending on the laser pulse energy, duration and focused beam diameter. In order to reduce the diameter of the plasma profile formed by the first nozzle and the concentration drop gap between the two nozzles, a one-side straight section was introduced in the first nozzle. The shock wave reflected from the straight section of the wall propagates parallel to the shock wave of the intersecting supersonic jets and ensures a minimal gap between the jets. The second-stage longitudinal plasma concentration profile could have an increasing gas density gradient to compensate for dephasing between the electron bunch and the plasma wave due to wave shortening with increasing plasma concentration.

Temporal phytoplankton dynamics and environmental variables in four Ethiopian soda lakes

We investigated the spatio-temporal dynamics of phytoplankton composition, chlorophyll-a as a proxy for algal biomass, and abundance in relation to environmental parameters in four Ethiopian soda lakes: Arenguade, Beseka, Chittu, and Shala. Triplicate water samples were collected from each lake from January to December 2020, four times in different seasons. Lake Chittu had the highest chlorophyll-a concentration, followed by Lake Arenguade, Beseka and Shala. Chlorophyll-a concentrations generally increased during the post rainy and dry season. The results of LR models are high for lakes Arengude, Beseka and Chittu. Lakes Shala and Beseka had the highest number of phytoplankton taxa, with both taxa composition and abundance dominated by Bacillariophyceae. Cyanoprokaryota, particularly Limnospira fusiformis, predominated in the abundance of Lakes Arenguade and Chittu. Water temperature, Secchi depth, turbidity, electrical conductivity, soluble reactive phosphorus, nitrate and silica significantly influenced the phytoplankton community structure. Long-term trend analysis revealed changes in phytoplankton biomass and lake taxonomic composition. The alteration in phytoplankton biomass and species composition of the lakes could be attributed to three factors: (1) frequent high-velocity explosions conducted for seismological studies in the past. This impact caused a dramatic increase in lake level in the case of Lake Beseka leading to a drop in nutrient concentration; (2) climate change and (3) salt content. Overall, our findings suggest that phytoplankton composition, biomass, and abundance varied according to seasonal fluctuations, emphasizing the possible effects of anthropogenic and natural causes on their community structure.

Diurnal Variation Characteristics of Raindrop Size Distribution Observed by a Parsivel2 Disdrometer in the Ili River Valley

The diurnal variation characteristics of raindrop size distribution (RSD) in the Ili River Valley are investigated in this study, using the RSD data from May to September during 2020-2021 collected by a Parsivel2 disdrometer in Zhaosu. Significant diurnal variations (02–07, 08–13, 14–19, and 20-01 local standard time (LST)) of precipitation and RSD in Zhaosu are revealed during the rainy seasons. Precipitation mainly occurs in the late afternoon and early evening. A higher concentration of small raindrops is observed in the morning, whereas more mid-size and large raindrops are observed in the afternoon. The RSD exhibits diurnal differences between different rainfall rate classes; the diurnal difference of RSD is more pronounced in the case of high rainfall rates. Stratiform precipitation can occur at any time of the day, yet convective precipitation mainly occurs during the late afternoon and early evening. The RSD of stratiform rainfall shows a similar distribution over the four time periods. For convective rainfall, the concentration of small raindrops is the highest (lowest) over 02–07 (14–19) LST, while the highest (lowest) concentration of medium and large drops is observed over 14–19 (02–07) LST. Convective rain in the Ili River Valley over 14–19 LST can be characterized as the continental convective cluster, while in the rest time of the day, it is neither in the maritime cluster nor in the continental cluster. The empirical relationships between the radar reflectivity factor and rainfall rate (Z-R) for stratiform and convective rain types are also derived. The purpose of this study is to advance our understanding of precipitation microphysics in arid mountainous region.

Higher rating of perceived exertion and lower perceived recovery following a graded exercise test during menses compared to non-bleeding days in untrained females.

The underrepresentation of the female population in exercise sciences could be attributed, at least in part, to difficulty in appropriately accounting for the effects of the menstrual cycle (MC). Previous studies examining the effects of the MC on aerobic performance and subjective measures of aerobic performance show conflicting results. Purpose: The study examined how the MC affects the objective and subjective measures of aerobic performance within untrained female participants and in comparison with untrained male participants assessed at similar time intervals. Methods: Twenty-one participants (12 females and 9 males) completed a graded exercise test (GXT) on a cycle ergometer. The female participants were tested during their early follicular (EF; menses), ovulatory (O), and mid-luteal (ML) phases of the MC. The male participants were included as the control group and were randomly assigned to a menstrual cycle phase for each visit. During GXT, maximal oxygen consumption (VO2max), respiratory exchange ratio (RER), maximal heart rate (HRmax), peak blood lactate, and rating of perceived exertion (RPE) were determined. Twenty-four hours post-exercise, the perceived recovery status (PRS) was assessed. The MC phase was estimated using basal body temperature (BBT) in the female participants. Results: The male participants obtained a higher peak power and VO2max compared to the female participants (p < 0.05). All objective measures of aerobic performance did not significantly differ across the MC phases or time points that were tested. In the untrained female participants, an effect of the MC phase on RPE was found, with RPE being higher at EF (8.92 ± 0.79) compared to O (7.67 ± 1.23; p < 0.05) and ML (7.75 ± 1.06; p < 0.05). In addition, an effect of the MC phase on PRS was found, with perceived recovery being lower at EF (6.83 ± 0.94) compared to O (8.83 ± 1.12) and ML (8.67 ± 0.65; all p < 0.005) for the untrained female participants. No significant differences in RPE and PRS were found between tests in the untrained male participants. The female participants had lower perceived recovery following EF (6.83 ± 0.94) compared with the male participants (9.00 ± 1.00; p < 0.001). Conclusion: The untrained female participants perceived greater exertion during GXT and impaired recovery following GXT in EF compared to O and ML. These results may be attributed to either a drop in female sex hormone concentrations or discomfort associated with menses. The male participants did not exhibit any changes over time. Future studies using subjective parameters such as perceived exertion to track the internal load of training in the naturally menstruating female population should consider menses.

Antimicrobial effect of chamomile-containing over-the-counter ear and eye drops.

Chamomile (Matricaria chamomilla) is a plant with known antimicrobial, anti-inflammatory, and analgesic properties. Homeopathic drops containing chamomile extract are often used for ear pain and chronic ear infections. We aimed to evaluate the antimicrobial effect of over-the-counter eardrops containing chamomile against organisms causing bacterial conjunctivitis and otitis externa. Liquid cultures of Streptococcus aureus and Pseudomonas aeruginosa were exposed to increasing concentrations of eardrops containing chamomile extract. Liquid cultures of S. aureus and Streptococcus pneumoniae were exposed to increasing concentrations of chamomile eye drops for 5, 10, 15, and 45 min. Colony forming units (CFUs) were assessed after 18 h. Viability assays for these organisms were performed using the resazurin microdilution assay. We observed a reduction in the number of P. aeruginosa CFUs when the bacteria were exposed to any of the three concentrations of the chamomile drops as early as 5 min, with maximal reduction upon exposure to the 30% concentration at 45 min. Reduction in S. aureus CFUs, on the other hand, was observed for all three concentrations as maximal in the 5 min of exposure. We observed a marked reduction in the number of S. aureus CFUs upon exposure to any of the three preparations of chamomile-containing eye drops, which was almost immediate at 10% concentration. Streptococcus pneumoniae reduction happened at 5 min and continued through the 45-min observation period for all three concentrations. Our findings suggest that over-the-counter ear drops containing chamomile extract could potentially be used as a non-prescription treatment for mild cases of otitis externa and bacterial conjunctivitis.

Relationship Between Hemoglobin Concentration in Pregnancy and Birth Weight of the Newborn

Background: Maternal hemoglobin during pregnancy is an important predictor of neonatal outcomes such as infant birth weight. The weight of the newborn is considered a crucial factor for the morbidity and mortality of newborns. The mother's hemoglobin fluctuates significantly during pregnancy. Objective: The aim of the the study was to assess the relationship between the mother's hemoglobin concentration during pregnancy and the birth weight of the newborn. Methods: Design-retrospective analysis of 672 pregnancies with recorded maternal hemoglobin concentration and newborn birth weight recorded in the pregnancy database in the delivery department of the Velika Kladuša Health Center in Bosnia and Herzegovina in the period from 2009 to 2010. Results and Discussion: The maximum mean birth weight was achieved with a hemoglobin concentration of 85-95 g/l. If the optimal drop in hemoglobin concentration does not occur during pregnancy, this condition is associated with an increased risk of giving birth to children with a lower birth weight for gestational age. Conclusion: The optimal drop in hemoglobin concentration during pregnancy is associated with the birth weight of the newborn. Hemoglobin deficiency below 105 g/l indicates an increased risk of low birth weight of the newborn.

Особенности коагуляции и дробления капель в газожидкостных турбулентных струях

In this paper, the mass exchange between drops of various sizes resulting from their coagulation and fragmentation in a two-phase jet is studied. Drops are combined into classes, and the drops of the isolated classes are assumed to consist of pure substances (components) in the initial cross-section of the jet. When moving away from the nozzle due to interparticle interaction, other components appear in the drops of all classes. The study of the variation in the component composition of drops makes it possible to analyze the intensity of mass exchange between drops and the ratio between coagulation and fragmentation of drops. Calculations have shown that coagulation and fragmentation of the drops occur simultaneously in the jet, but coagulation prevails over fragmentation. At a short distance from the nozzle, a significant change is observed in the fraction of components in the drops, and further their component composition remains constant. As the concentration of drops increases, the ratio between components in the drops tends to the ratio between the volume concentrations of the drops from the isolated classes in the initial cross-section of the jet.