Uptake Rate Research Articles

Plasticity in nitrogen form uptake and preference in response to long-term nitrogen addition of the main tree species in a temperate old growth forest

ABSTRACT We conducted a short-term field hydroponic 15N labeling experiment to study the effects of different nitrogen (N) addition treatment on the N uptake preference and rate of plant fine roots in a temperate old growth forest in 2018. The results indicated that the N preference of dominant tree species for different N chemical forms was not influenced by the N addition, with the N acquisition pattern being ammonium > nitrate > glycine. However, N addition altered the plant's N uptake rates. Under low N treatment, the uptake rates of glycine for three target tree species significantly increased. Both low and medium N additions significantly enhanced the NH4–N uptake rate, but had little impact on the NO3–N uptake rate. Conversely, high N addition exerted negative effects on NO3–N and NH4–N uptake rate. Different tree species may flexibly adapt to new environmental conditions by adapting to their root morphology and the relationship between plant growth and N uptake. N addition has pronounced effects on N uptake rate and root morphology traits of dominant tree species. Overall, this study contributes to a deeper understanding of the response of N uptake patterns in temperate forests to long-term N addition.

Post abortion contraceptive uptake and continuation rates at Korle-Bu Teaching Hospital, Accra, Ghana

Introduction: The tragedy of unsafe abortion is that it is one of the easily preventable causes of maternal death. In Ghana, the maternal mortality ratio was 319/100,000 live births. (WHO, 2015) of which 11% of these were abortion related. 13% of abortions had complications including chronic pelvic pain, offensive discharge and uterine perforation In spite of the above, this study sought to find out factors that affect uptake and continuation rates of post abortion contraception at the Korle Bu Teaching Hospital. Methods: This was a longitudinal study using interviewer administered questionnaire of women reporting for elective termination of pregnancy or for uterine evacuation for incomplete abortion either induced or spontaneous. Participants were followed up by telephone calls at end of 1, 3 and 6 months. Simple proportions was calculated for post-abortion contraception uptake and continuation rates. Multiple logistic regression was used to determine factors associated with uptake and continuation rates. A p-value of less than or equal to 0.05 was considered as statistically significant. Results: The study included 338 participants. The overall uptake was 132 (39.1%). Eighty-seven (25.7%) on discharge and 45 (13.4%) additional uptake within one month of the follow-up. Continuation rate at 6 months was 68.9%. Significantly associated factors were educational level, employment and marital status, gravidity/parity and previous contraceptive use. Conclusion: Post-abortion contraception uptake of 39.1% with 68.9% continuation rate at 6 months found in this study is low. This implies high unmet need for post-abortion contraception that needs to be addressed urgently.

The pollution characteristics and risk assessment of microplastics in mollusks collected from the Bohai Sea

Microplastics (MPs) pollution in the marine environment has become a global problem. In this study, a number of 21 mollusk species (n = 2006) with different feeding habits were collected from 11 sites along the Bohai Sea for MPs uptake analysis. The MPs in mollusk samples were isolated and identified by micro-Fourier Transform Infrared Spectroscopy (μ-FTIR), and an assessment of the health risks of MPs ingested by mollusk consumption is also conducted. Approximately 91.9 % of the individuals among all the collected species inhaled MPs, and there was an average abundance of 3.30 ± 2.04 items·individual−1 or 1.04 ± 0.74 items·g−1 of wet weight. The shape of MPs was mainly fiber, and a total number of 8 polymers were detected, of which rayon had the highest detection rate (58.3 %). The highest abundance, uptake rate and polymer composition of MPs was observed in creeping types, suggesting that they might ingest these MPs from their food. The gastropod Siphonalia subdilatata contains the highest levels of MPs, which may increase the risk of human exposure if consumed whole without removing the digestive gland. The polymer risk level of MPs in these mollusks was Level III (H = 299), presenting harmful MPs such as polyvinyl chloride. In terms of human exposure risk, the average risk of human exposure to MPs through consumption of Bohai mollusks is estimated to be 3399 items·(capita·year)−1 (424–9349 items·(capita·year)−1). Overall, this study provides a basis for the ecological and health Risk assessment of MPs in mollusks collected from the coastline of China.

KÜÇÜK HÜCRELİ DIŞI AKCİĞER TÜMÖRLERİNİN DEĞERLENDİRİLMESİNDE Tc-99m MIBI SPECT’İN YERİ

Objective: In this study, it was aimed to investigate the role of Tc-99m MIBI scintigraphy in the diagnosis and evaluation of non-small cell lung cancers and also to evaluate the use of MIBI scintigraphy and MDP bone scintigraphy together in the detection of metastases. Methods: For this purpose, 30 patients with non-small cell lung cancer and 15 patients with benign lesions other than lung cancer (as a control group) were included in the study. By applying Tc-99m MIBI and Tc99m MDP scintigraphy to whole patients with benign and malign lung lesions, anterior-posterior planar and SPECT MIBI images were obtained. Bone scintigraphy was performed as whole-body images. Scintigraphic findings were compared with the histopathological diagnosis of patients. Data were analyzed statistically. Results: According to the result of the findings, the sensitivity, specificity, positive, predictive value, negative predictive value, and accuracy rate of Tc-99m MIBI scintigraphy in the detection of non-small cell lung tumors were determined as 87%, 93.5%, 96%, 77.7%, and 88.8%, respectively. Scintigraphic findings were evaluated quantitatively and visually. While there was no statistically significant difference between the early uptake rates of non-small cell lung tumors and benign lesions in the quantitative evaluation using planar MIBI images, late Tc-99m MIBI uptake rates were significantly higher in lesions with non-small cell lung tumors than that of benign lesions. However, it was detected that both the early and late uptake ratios were significantly higher in malign lesions than in benign lesions in the quantitative evaluation of SPECT images. It was observed that MIBI washout in benign lesions was higher than in malignant lesions in visual washout analysis. Additionally, multiple bone metastases were observed in 14 patients on the visual evaluation of bone scan of the patients with non-small cell lung cancer. Tc-99m MDP uptake was not observed in the malignant lung lesion region or in the soft tissue except the lesion. Conclusion: In light of the findings, it was concluded that Tc-99m MIBI scintigraphy is a noninvasive method with high sensitivity and specificity that can be used to differentiate non-small cell lung tumors from benign lesions.

Investigating Teachers’ Oral Corrective Feedback and Students’ Uptake in Grade 6 Bhutanese Primary Classrooms

Oral corrective feedback (OCF) plays an important role in language teaching and learning, but little research has examined Bhutanese teachers’ practices of OCF on students’ speaking performance and uptake. This paper reports on a mixed-method approach to investigate the rate of students' uptake on teachers' OCF within an ESL setting in Bhutanese grade six primary classrooms. Convenience sampling was applied to gather data from observations of two teachers and fifty-seven students in a primary school. The results of content analysis from classroom observations indicate that the teachers used four types of OCF: explicit correction, recast, metalinguistic feedback, and repetition, with recast being the highest used. The results showed a high degree of student participation, which resulted in error correction following the teachers' OCF. It is suggested that different classes be studied to see if there are differences in the effects of OCF on students.

Analysis of Carbon Sequestration Rate in Seaweed (Kappaphycus alvarezii) Based on Environmental Mitigation

Blue economy is a development concept that develops by relying on marine or aquatic resources. An increase in carbon dioxide (CO2) in the atmosphere is fueling climate change. This study aims to analyze the rate of carbon uptake in the waters, using seaweed Kappaphycus alvarezii which utilizes carbon to be converted into biomass before returning to the air. The results showed that highest carbon absorption rate was found in location A with the highest total carbon absorption of 94.87±0.77 tons C/planting cycle, then treatment B with 83.96±0.54 tons C/planting cycle, and the lowest in treatment C with 76.88±0.18 tons C/planting cycle. Water quality parameters are still mostly in decent condition for the cultivation of Kappaphycus alvarezii seaweed. Salinity conditions of waters are relatively high (35-39 ppt) even though the optimum seaweed grows in the range of 30-34 ppt. The conclusion of the study is that the highest total carbon is found at Location A, which is 94.87±0.77 tons C/planting cycle. The suggestion of this study is that it is necessary to analyze the suitability of seaweed cultivation land with various water quality parameters, so that mapping of potential types of seaweed that can be cultivated according to the characteristics and quality of the waters.

Fyzická aktivita detských pacientov s nešpecifickými črevnými zápalovými ochoreniami – výhody a limitácie

Summary: Introduction: Inflammatory bowel diseases (IBDs) are a group of diseases including Crohn’s disease, ulcerative colitis and unclassified IBD. They are chronic, immune-mediated inflammatory diseases of the gastrointestinal tract. Due to their extraintestinal manifestation, they are considered to be systemic diseases. IBD has a negative impact on health-related quality of life. The treatment is life-long and may be accompanied by side effects. Low-intensity activity of moderate duration is sufficient to elicit improvements in fitness, decrease stress, and improve symptoms. In this study, the relationship between physical activity and IBD development and course is described. Aims: To assess the relationship between physical activity and exercise capacity and the severity and course of IBD. Methods: Probands with IBD and healthy controls underwent pulmonary function testing (PFT) and cardiopulmonary exercise testing (CPET). The results were compared between these two groups; in the IBD group, the results were correlated with disease activity parameters as well. In the IBD group, the probands were encouraged to perform regular physical activity. After 0.5–1 year, they underwent another CPET. Their exercise capacity development was objectively assessed and it was correlated with their IBD development. Results: Forty-one children were included in the study. Twenty of them were healthy controls, while 21 comprised the IBD patient group. These probands underwent the PFT and CPET. When comparing healthy controls and IBD patients, significant differences were found in peak oxygen uptake and peak work rate. In the IBD group, a negative correlation was found between peak work rate and C-reactive protein concentration. In faecal calprotectin, a significant correlation was found only in the subgroup with ulcerative colitis – the negative correlation with peak oxygen uptake and partial pressure of CO2 in exhaled air in the peak of the exercise. PCDAI correlated positively with ventilatory index, peak dead space and tidal volume ratio but negatively with peak work rate, work rate at the time of anaerobic threshold, peak oxygen uptake and oxygen uptake efficacy slope. In PUCAI, we found a positive correlation with CO2 ventilatory uptake at the time of anaerobic threshold and negative correlations with peak oxygen uptake and oxygen uptake efficacy slope. In further CPET in the IBD group, a significant decrease was found in faecal calprotectin and PCDAI or PUCAI; there were also positive correlations between PCDAI/PUCAI changes and resting heart rate changes. The negative correlation was found in the correlation with the changes in peak oxygen uptake, metabolic index and ventilatory equivalent for CO2 at the time of anaerobic threshold. Conclusion: These results suggest that regular recreational physical exercise positively impacts IBD. When adhering to treatment recommendations, doing sport professionally is also possible. Key words: inflammatory bowel diseases – physical activity

Pap smear test: Knowledge, Attitude and practice among the female nursing and paramedical staffs of Maternity and Child Hospital, Al Ahsa, Saudi Arabia

Background: A Pap smear test is a microscopic examination of uterine cervix which can detect the precancerous changes in the cervix (cervical dysplasia). Presence of human papilloma virus (HPV) and presence of precancerous changes in the cervical cells confirms the diagnosis. So early detection of HPV (causative factor) and precancerous changes in the cervix (cervical dysplasia) can help in early treatment of cervical cancer and complete cure. Being asymptomatic at presentation it is important to screen all the women at risk of getting cervical cancer for early diagnosis and its secondary prevention. Knowledge is one of the important determinants predicting health behaviors and an effective factor in performing screening methods in the population. However, acquiring knowledge only is not adequate and success of a prevention programme depends on the positive preventive attitude and correct practice of the population. The present study was done to assess the knowledge, attitude and practice of the healthcare workers at MCH hospital, Al Ahsa Saudi Arabia towards the Pap smear screening test. Results: A total of 217 out of 258 staffs responded the online questionnaires making the response rate of 85%. The mean age of the participants was 32. 83 ± 7. 20 Std. Dev. (Range 21-61 years). Majority of the participants (N= 180, 82. 9%) were married. Seventy percent of the participants (N=152) were staff nurse. Sixty four percent of the participants were graduate (N=139). The mean knowledge of the participants was 6. 31 ± 3. 24 Std. Dev. (Range: 2 -10). More than fifty percent of the participant (N=109) did not have good knowledge about Pap smear test. The mean of positive attitude score was 3. 56 ±1. 19 Std. Dev. (Range: 00-5). Fifty eight percent of the participant (N=128) had positive attitude towards Pap smear test. The mean of practice score was 2. 21 ±1. 00 Std. Dev. (Range: 00 – 4). Sixty eight percent of the participants (N=191) did not have good practice towards Pap smear test. The attitude of staff nurses was significantly positive (p=0. 024) than those of other medical staffs. The practice of the nursing staffs towards the Pap smear test was significantly negative (P=0. 000) than those of other medical staff. There were no significant difference in the knowledge, attitude and practice score between different age groups and marital status of the participants. Conclusion: This study has demonstrated a moderate level of knowledge and attitude among the paramedical and nursing staffs of Maternity and Child Hospital towards Pap smear screening test. However good knowledge and attitude did not translate into good practice in most of them especially among the nursing staffs. The rate of uptake for Pap smear test was low. The major reason for low uptake of Pap smear screening among the respondents include, no recommendation by any doctors, embarrassment, lack of knowledge about the Pap smear, lack of time and fear of the test result.

Effect of microplastic particles on the population growth rate and clearance rate of selected ciliates (Protista, Ciliophora).

Microplastics (MPs), due to their micro size, which overlaps with the typical food size of various aquatic organisms, can be ingested and move up the food chain, accumulating in the bodies of organisms at higher trophic levels. Few studies have focused on the uptake of MPs by ciliates, which are an important element of the microbial cycle. Three different ciliate species were used in this study: Blepharisma japonicum, Euplotes sp., and Spirostomum teres, as well as polystyrene beads with diameters of 1 and 2µm at two concentrations (106 and 107 beads × mL-1). The results of the experiments showed that MPs have a variable, species-specific effect on the population growth rate of ciliates, which is directly dependent on their concentration in the environment (P < 0.01). It was also observed that the number of MPs ingested changed over time depending on their concentration and size. On average, the highest number of ingested MPs (883.11 ± 521.47) was recorded at 60min of exposure to a low concentration of small beads in B. japonicum. The lowest number of beads was ingested after 5min of exposure to a low concentration of large beads in the same species. The rate of MP uptake by the ciliate species was significantly dependent on their concentration, exposure time, and size (P < 0.001). The highest clearance rate was observed in the fifth minute of the experiment in the environment with the lowest MP concentration.

Leaves stimulate aquatic phosphorus uptake by dark‐grown but not by light‐grown microbial communities in sediments: A laboratory study

Abstract It is a widely discussed topic in restoration ecology to use organic carbon (OC) management to increase nutrient uptake in chronically loaded agricultural streams. However, although nitrate uptake has been shown to correlated closely with the availability of dissolved OC, this relationship is less clear for phosphate. Likewise, the role of particulate OC (POC) on stimulating nutrient uptake has to be clarified. We aimed at investigating the effects of leaf additions on the net uptake of soluble reactive phosphorus and nitrate‐nitrogen from the water column by benthic biofilms in combined laboratory flume and batch experiments. Fine sediments were colonised under nutrient‐enriched conditions in the dark (dark‐grown heterotrophic biofilms) and under a 12/12‐hr dark/light cycle (light‐grown photoautotrophic biofilms) in flumes. In each light treatment, half of the biofilms were grown under strong OC‐limitation, the other half under near‐optimal C:N:P ratios. For the uptake experiments, the colonised sediments were incubated in nutrient‐enriched water to which (1) fresh alder leaves, (2) pre‐leached leaves, or (3) no leaves were added. Net nutrient uptake (or release) rates were determined via the change in nutrient concentrations in the water column over time. Net phosphorus uptake by dark‐grown biofilms was significantly increased by the addition of leaves. Despite their high initial nutrient leaching, fresh leaves showed stronger stimulating effects on the net P uptake than leached leaves over the entire experiment. Furthermore, biofilms grown under near‐optimum C:N:P ratios responded stronger to the POC supply than biofilms grown under C‐limited conditions. In contrast to dark‐grown biofilms, leaf additions had no significant effects on the net P uptake by light‐grown biofilms. We also found no effects of leaf additions on net nitrate uptake. Our study shows that an increased POC supply in nutrient‐impacted streams may boost heterotrophic phosphate uptake. However, the stimulating effect of the POC addition depends on a variety of POC‐dependent (e.g. respiration, heterotrophic assimilation, denitrification) and independent (e.g. adsorption, photoautotrophic assimilation) processes, making nutrient control via POC management challenging. We suggest application of management approaches that focus on restoration of riparian areas and wetlands to increase the amount of natural, complex POC with a moderate degradability, thus keeping the heterotrophic metabolism low but potentially stimulating in‐stream N and P retention.

The effect of fishing-capture stress on the oxygen uptake rate and swimming activity of the holocephalan Callorhinchus milii.

Overfishing, capture mortality, and consequences following the release of surviving animals represent severe threats to chondrichthyans. Although holocephalans are common bycaught and discarded species, other than postrelease mortality, little is known of fishing capture stress impacts. The stress response elicited after capture, essential to increase survival chances, is energetically demanding and affects the amount of energy available for other biological activities, with potential long-term impairments. We measured the effect of 30-min simulated gillnet capture on oxygen uptake rate (ṀO2 ), a proxy for metabolic rate and energy use, on recovery pattern, and on swimming activity of elephant fish (Callorhinchus milii). Immediately after simulated capture, Active and Inactive ṀO2 , measured during swimming and resting periods, respectively, were 27.5% and 43.1% lower than precapture values. This metabolic decline is likely an adaptation for reducing the energy allocated to non-essential activities, thus preserving it to sustain the stress response and processes essential for immediate survival. Supporting this, after gillnet capture, animals decreased their swimming time by 26.6%, probably due to a reduction in the energy allocated to movement. After 7 days, swimming activity and both Inactive ṀO2 and Active ṀO2 returned to precapture values. Although metabolic decline may enhance survival chances, the associated decreased swimming activity might increase predation risk and slow the physiological recovery after a fishing event. Moreover, some of the activities involved in Inactive ṀO2 are fundamental for life maintenance and therefore its depression after a capture event might have long-term repercussions for life sustenance and health.

Simulation of the biodegradable behavior of composite bone plate under human body environment

The Young’s modulus degradation of a biodegradable composite based on the exposure time to phosphate-buffered saline (PBS) solution was simulated by estimating the material’s effective diffusion coefficient. The relationship between PBS uptake rate and material removal was investigated by comparing the finite element analysis and experimental results, and a criterion for the material removal of finite elements was proposed for an accurate material degradation simulation. The diffusion coefficient was calibrated to determine the best fit for the PBS uptake rate based on exposure time. The degradation behavior of a bone plate made of a fully biodegradable composite was analyzed using a calibrated diffusion coefficient; it was found that the screw hole parts were severely damaged owing to PBS uptake, which induced premature structural failure. To address this drawback, a hybrid bone plate composed of a nondegradable composite and a Mg wire/Polylactic acid (PLA) composite was introduced; its serviceability was verified using finite element analysis.

Natural deep eutectic solvent: A novel and green mordant for the natural dye

Applying natural dye is a green and available approach for the dyeing and simultaneous functionalizing of textiles. However, the commonly used mordant of metal ions to improve the dyeing effect results in massive toxic wastewater production, which decreases the environmentally friendly characteristics. In this work, the mordant and water substitute ability of choline chloride-ethylene glycol natural deep eutectic solvent (NADES), defined as the mixture of two or more primary metabolites at a particular composition becoming liquids via H-bond forces, was investigated during the dyeing process because it has been used as a green extraction and stability agent for the natural dye. To this end, the NADES and metal ion were used in three mordant dyeing wool and cotton processes of Platycodon Grandiflorus root dye, and the color and functionalization effect were compared to verify the method advance. The result indicated that natural deep eutectic solvent had a better effect as a mordant than the metal ion by enhancing the dye solubility, the dye uptake rate of fiber, and the dye polymerization trend via rich H-bonds among fiber, dye, and NADES. The dyed textile had an excellent functional performance, including UV resistance, antibacterial, antioxidation, and burning difficulty, with the preferable fastness. This method also showed good universality for other natural dyes and NADESs. Compared to the existing mordant dyeing technologies, the proposed technology had lower chemical reagent usage, cost, and energy consumption, whose residual solvent had good reusability for at least 10 times and better degradability. Overall, this paper supplied a potential and green approach using NADESs as alternatives to metal ions for the mordant dyeing textile using natural dye.

Experimental investigation and comparative environmental impact analysis of conventional and naturally occurring kinetic hydrate inhibitors in offshore environments using toxicity and bioconcentration tools

In this present study, an in vivo experiment was carried out to determine the tendencies of a naturally occurring high-phenolic compound red-onion skin extract (HPC-ROSE) and conventional N-Vinylcaprolactam (N-VCAP) kinetic hydrate inhibitors (KHIs) to bio-accumulate in offshore environment through the analysis of their uptake and depuration kinetics by a Fish-Chemical Model using Cyprinus carpio marine invertebrate. This test was performed in the laboratory in a flow through experimental set up according to the guidelines by [49] (Fish-chemical exposure test). The uptake duration was 10 days with a depuration period of twenty days. The inhibitor toxicity test was evaluated by determining the 50 % lethal concentration (LC50) as highlighted by OSPAR Commission protocols. The solubility of the inhibitors was determined by a column elution technique. Similarly, a proton-enabled nuclear magnetic resonance (1HNMR) technique was used to measure the partitioning characteristics of the inhibitors in an immiscible mixture of octanol and water (Kow) by 1HNMR spectroscopy using a benchtop low-field NMR spectrometer. OSPAR Commission and ASTM standard protocols were used for the laboratory investigation of the static sediment toxicity tests. A reference chemical substance of known BCF and solubility (Ethyl Acetate, EtOAc) was used as control to check the experimental progression. The stock solution was prepared by solid phase desorption mechanisms. The HPC-ROSE does not constitute environmentally significant risk to aquatic life owing to its lower BCF values between 215 L/kg - 251.5L/Kg, Log-Kow of 1.2 and higher lethal concentration of 25140 mg/L. Unlike the NVCAP which is very toxic with lower lethal concentration of 1280 mg/L and higher BCF values in the range of 442.5L/Kg to 485 L/kg with Log-Kow of 1.5. Furthermore, Nuclear magnetic resonance (1HNMR) is a simple and reliable method of estimating partition coefficient characteristics (Kow) because the obtained Log-Kow values showed good agreements with that of shake flask and high-performance liquid chromatography techniques. Also, the chemical concentration in water has an inverse relationship with uptake rate constant (K1) and steady-state bioconcentration factor (BCFss). Finally, the theoretically estimated BCFs were higher than the steady-state (BCFss) values that were obtained from laboratory experiments for the different inhibitor samples and at all concentrations. This is due to the route by which Log-Kow was estimated since most of the empirical models are usually one-factor model consisting of partition coefficient and BCF.

The use of small emitter flow rate in drip irrigation favored methane uptake in arid potato fields

Drip irrigation has been widely used in agriculture, while the mechanism underlying the effect of drip irrigation system design and management on soil methane (CH4) uptake have not been fully studied. A two-year experiment was conducted to explore the effects of different emitter flow rates of drip irrigation (1.3, 2.0, and 3.0 L/h) on CH4 uptake in potato fields in an arid region of Northwest China. Results showed that compared to emitter flow rates of 2.0 and 3.0 L/h, the 1.3 L/h flow rate significantly increased the cumulative CH4 uptake by 6.3–16.2%, mainly due to the increase in the abundance of the pmoA gene by 15.2–49.5%, and by the decrease of water-filled pore space (WFPS), increasing the effective CH4 diffusion coefficient (Dp) and soil oxygen concentration in the topsoil. A hump-shaped relationship was found between WFPS and CH4 uptake flux, and the optimum WFPS for CH4 uptake was about 44.8%. The treatment with an emitter flow rate of 1.3 L/h exhibited the highest frequency (28.6%) of favorable WFPS for CH4 uptake, compared to the 2.0 and 3.0 L/h treatments. In addition, significant negative quadratic relationships were observed between both Dp and soil oxygen with CH4 uptake, and optimal values were 0.02 cm2 s−1 and 18.7%, respectively. There was no significant difference in CH4 uptake between 2.0 and 3.0 L/h treatments in 2021 and 2022, due to high WFPS and low oxygen concentrations in both treatments. Multiple linear regressions indicated that soil oxygen concentration became a major limiting factor under emitter flow rates of 2.0 and 3.0 L/h. This study provides insights into mechanisms of soil CH4 uptake in drip-irrigated farmland, which gives guidance on developing irrigation strategies for sustainable production and CH4 mitigation in irrigated arid land.

Modeling large-scale bioreactors with diffusion equations. Part II: Characterizing substrate, oxygen, temperature, carbon dioxide, and pH profiles.

Large-scale fermentation processes involve complex dynamic interactions between mixing, reaction, mass transfer, and the suspended biomass. Empirical correlations or case-specific computational simulations are usually used to predict and estimate the performance of large-scale bioreactors based on data acquired at bench scale. In this two-part-study, one-dimensional axial diffusion equations were studied as a general and predictive model of large-scale bioreactors. This second part focused on typical fed-batch operations where substrate gradients are known to occur, and characterized the profiles of substrate, pH, oxygen, carbon dioxide, and temperature. The physically grounded steady-state axial diffusion equations with first- and zeroth-order kinetics yielded analytical solutions to the relevant variables. The results were compared with large-scale Escherichia coli and Saccharomyces cerevisiae experiments and simulations from the literature, and good agreement was found in substrate profiles. The analytical profiles obtained for dissolved oxygen, temperature, pH, and were also consistent with the available data. Distribution functions for the substrate were defined, and efficiency factors for biomass growth and oxygen uptake rate were derived. In conclusion, this study demonstrated that axial diffusion equations can be used to model the effects of mixing and reaction on the relevant variables of typical large-scale fed-batch fermentations.

Characterization of a Southern Ocean deep chlorophyll maximum: Response of phytoplankton to light, iron, and manganese enrichment

AbstractSouthern Ocean phytoplankton growth is limited by low iron (Fe) supply and irradiance, impacting the strength of the biological carbon pump. Unfavorable upper ocean conditions, such as low nutrient concentrations, can lead to the formation of deep chlorophyll or biomass maxima (DCM/DBM). While common in the Southern Ocean, these features remain understudied due to their subsurface location. To increase our understanding of their occurrence, we studied the responses of phytoplankton communities from a Southern Ocean DCM to increasing light, Fe, and manganese (Mn) levels. The DCM communities were light‐ and Fe‐limited, but light limitation did not increase phytoplankton Fe requirements. The greatest physiological responses were observed under combined Fe/light additions, which stimulated macronutrient drawdown, biomass production and the growth of large diatoms. Combined Mn/light additions induced subtle changes in Fe uptake rates and community composition, suggesting species‐specific Mn requirements. These results provide valuable information on Southern Ocean DCM phytoplankton physiology.

Mineral Particles in Foliar Fertilizer Formulations Can Improve the Rate of Foliar Uptake.

The application of foliar sprays of suspensions of relatively insoluble essential element salts is gradually becoming common, chiefly with the introduction of nano-technology approaches in agriculture. However, there is controversy about the effectiveness of such sparingly soluble nutrient sources as foliar fertilizers. In this work, we focussed on analysing the effect of adding Ca-carbonate (calcite, CaCO3) micro- and nano-particles as model sparingly soluble mineral compounds to foliar fertilizer formulations in terms of increasing the rate of foliar absorption. For these purposes, we carried out short-term foliar application experiments by treating leaves of species with variable surface features and wettability rates. The leaf absorption efficacy of foliar formulations containing a surfactant and model soluble nutrient sources, namely Ca-chloride (CaCl2), magnesium sulphate (MgSO4), potassium nitrate (KNO3), or zinc sulphate (ZnSO4), was evaluated alone or after addition of calcite particles. In general, the combination of the Ca-carbonate particles with an essential element salt had a synergistic effect and improved the absorption of Ca and the nutrient element provided. In light of the positive effects of using calcite particles as foliar formulation adjuvants, dolomite nano- and micro-particles were also tested as foliar formulation additives, and the results were also positive in terms of increasing foliar uptake. The observed nutrient element foliar absorption efficacy can be partially explained by geochemical modelling, which enabled us to predict how these formulations will perform at least in chemical terms. Our results show the major potential of adding mineral particles as foliar formulation additives, but the associated mechanisms of action and possible additional benefits to plants should be characterised in future investigations.

Batch Fabrication of Electrospun PAN/PU Composite Separators for Safe Lithium-Ion Batteries

As an important element of lithium-ion batteries (LIBs), the separator plays a critical role in the safety and comprehensive performance of the battery. Electrospun nanofiber separators have a high porosity and good electrolyte affinity, which are favorable to the transference of lithium ions. In this paper, the batch preparation of polyacrylonitrile (PAN)-based nanofiber separators are obtained via spherical section free surface electrospinning (SSFSE). Introducing an appropriate amount of polyester polyurethane (PU) can effectively enhance the mechanical property of PAN nanofiber separators and help the separators resist the external force extrusion. The results show that when PAN:PU = 8:2, the porosity and electrolyte uptake rate of the composite nanofiber separator (PAN-2) are 62.9% and 643.3%, respectively, exhibiting a high ionic conductivity (1.90 mS/cm). Additionally, the coin battery assembled with PAN-2 as a separator (LiFePO4/PAN-2/lithium metal) shows good cycling performance and good rate performance, with a capacity retention rate of 93.9% after 100 cycles at 0.5 C, indicating that the battery with PAN-2 has a good application potential in advanced energy storage.

Modeling the effect of CO2 limitation in continuous fermentation for biosuccinic acid production

The present work investigates a new mathematical formulation for the continuous fermentation production of biosuccinic acid. The model takes into account the effect of CO2 limitation by the introduction of a specific production rate term that dynamically regulates the formation of the fermentation products. A good model prediction is achieved at different continuous conditions where glucose and sugars-rich industrial waste are utilized as substrates. By model prediction and experimental results, a change in the products ratio is observed when the liquid concentration of CO2 decreases below 0.18 g/L. A biosuccinic acid titer of 14.94 ± 0.97 g/L was achieved in the continuous process, with a maximum productivity of 1.18 g/L h, and a CO2 uptake rate of 0.258 ± 0.041 g/Lh. Overall, the presented model demonstrated to be a reliable tool to successfully forecast the fermentation outcomes and explain the CO2 limitation effects on the product and by-products formation rate. Furthermore, the application of the model to the fermentation process presents a valuable link between the production capacity and the accurate prediction of the CO2 uptake potential.