Nelson's Method Research Articles

Compositional nutrient analysis of greenhouse grown ryegrass (Lolium multiforum) fertilized with raw and hydrothermal-treated igneous rock as diagnostic tool for balanced fertilization in tropical environments

Due to the escalating demand for conventional potassium sources, and their unavailability in many African countries, there is a growing interest in hydrothermally treated igneous rocks as viable alternatives. These materials exhibit promising potential in enhancing potassium release, comparable to traditional sources like muriate of potash (M.O.P.). However, it remains uncertain whether they can adequately fulfill the nutrient requirements of plants. In this study, we evaluated nutrient balance in ryegrass (Lolium multiflorum) using raw and hydrothermally treated K-bearing silicate rocks as fertilizers. The Compositional Nutrient Diagnostic (CND) approach was used to assess the plants’ nutrient status, involving identification of high-yield subpopulations, and setting a yield cutoff. We derived a theoretical threshold for nutrient imbalance (CNDr2) using statistical methods like the chi-square distribution function and low-yield subpopulation proportion. CNDr2 was validated via Cate–Nelson partition and sum of squared individual nutrient indexes. Results showed a yield cutoff of 37.759 kg ha−1, distinguishing low-yield and high-yield subpopulations based on cumulative variance ratio functions from survey data. The theoretical threshold derived using the chi-square function was 10.1, subsequently validated by the Cate–Nelson method. Critical CND nutrient indices were symmetrical around zero, but their sum indicated foliar nutrient imbalance, notably zinc, potassium, and copper excess, attributed to 20 interactions identified (4 synergetic and 16 antagonistic). This study underscores hydrothermal treatment’s efficacy in improving nutrient availability and achieving a balanced nutrient profile compared to raw materials. It offers a promising solution for enhancing agricultural productivity, especially in tropical regions like Africa, where traditional sources are scarce.

The effect of an organomineral chelate complex on the amylolytic activity of intestinal enzymes of some fish species

To date, there is a large amount of information regarding the effect of heavy metals on the hydrolases of the digestive tract. It has been established that even biogenic metals in high concentrations can have a toxic effect. The assessment of the activity of digestive hydrolases is relevant, since a change in their activity has a direct effect on the effectiveness of assimilation of food. Amylolytic hydrolases help to provide the body with carbohydrates (along with fats) – the main sources of energy for fish. A decrease in the intake of carbohydrates will lead to a violation of metabolic processes and, as a result, underdevelopment and death of fish. The aim of the study was to determine the effect of an organomineral chelate complex on the amylolytic activity of intestinal enzymes of some fish species. The research was conducted at the Department of Biochemistry and Physiology of the St. Petersburg State University of Veterinary Medicine and on the basis of two fisheries in the Leningrad Region. The fish of the experimental groups (n = 10) were given an additive for 30 days, the data were compared with the control (n = 10). The drug was given together with the feed once a day, at a concentration of 0.5 g / kg (feed weight). Fingerlings (0+) of 3 species of freshwater bony fish were used as research objects: Carassius auratus (n=20), Cyprinus carpio (n=20), Oncorhynchus mykiss (n=20). Amylolytic activity was determined in the total homogenets of the intestinal mucosa of fish. The activity was assessed by the increase in hexoses by the Nelson method in the modification of Ugolev, Jesuitova. The detection was carried out on a photoelectric KKK-3 photometer. Based on the studies obtained, it can be concluded that the use of an organomineral chelate complex in the studied dosage (previously worked out in conditions of determining acute and chronic toxicity for fish) does not have a negative effect on the amylolytic activity of intestinal enzymes. There was no significant decrease in amylolytic activity in all experimental groups. Based on this, it is possible to recommend the use of a chelate complex for fish in industrial aquaculture.

Structural damage identification using an optimization technique based on generalized flexibility matrix

Abstract A generalized flexibility matrix-based objective function utilized for structure damage identification is firstly constructed. After transforming the damage identification into a constrained nonlinear least squares optimization problem, the trust-region algorithm is applied to find the solution of the inverse problem in multiple damage cases. Thereinto, the sensitivity analysis of the objective function with respect to the design variables is derived using the Nelson's method. At last, two numerical examples with several damage cases are investigated, including a steel truss bridge model as well as a drilling rig derrick model. Based on the computational results, it is evident that the presented approach provides excellent validity and reliability for the large and complicated engineering structures.

Entropy of electron gas in semiconductor nanowires

The thermodynamic potential and entropy of the electron gas of a semiconductor nanowire are obtained. When calculating the entropy of an electron gas with a nonparabolic energy dispersion, the Nelson method was used. The entropy of the electron gas with the value of the chemical potential of the smaller line, which is equal to or greater than the energy of an arbitrary discrete energy level, is studied. An analytical expression for the entropy is obtained in the case when the chemical potential of the electron gas is equal to the energy of the discrete level. The temperature dependences of the entropy of the electron gas of semiconductor nanowires on the degree of nonparabolicity of the energy dispersion law are found.

A comparison of five models in predicting surface dead fine fuel moisture content of typical forests in Northeast China

IntroductionThe spread and development of wildfires are deeply affected by the fine fuel moisture content (FFMC), which is a key factor in fire risk assessment. At present, there are many new prediction methods based on machine learning, but few people pay attention to their comparison with traditional models, which leads to some limitations in the application of machine learning in predicting FFMC.MethodsTherefore, we made long-term field observations of surface dead FFMC by half-hour time steps of four typical forests in Northeast China, analyzed the dynamic change in FFMC and its driving factors. Five different prediction models were built, and their performances were compared.ResultsBy and large, our results showed that the semi-physical models (Nelson method, MAE from 0.566 to 1.332; Simard method, MAE from 0.457 to 1.250) perform best, the machine learning models (Random Forest model, MAE from 1.666 to 1.933; generalized additive model, MAE from 2.534 to 4.485) perform slightly worse, and the Linear regression model (MAE from 2.798 to 5.048) performs worst.DiscussionThe Simard method, Nelson method and Random Forest model showed great performance, their MAE and RMSE are almost all less than 2%. In addition, it also suggested that machine learning models can also accurately predict FFMC, and they have great potential because it can introduce new variables and data in future to continuously develop. This study provides a basis for the selection and development of FFMC prediction in the future.

Induction of Extracellular Lytic Enzymes from Aureobasidium pullulans

Aims: The objective of this work was to analyze the production of some extracellular lytic enzymes of the fungus Aureobasidium pullulans.
 Methodology: The fungus was isolated from Valencian orange and was cultivated on Mathur medium modified with polygalacturonic acid (2% w/v) or xylan (2% w/v) as a carbon source, and they were incubated at 28°C, with constant stirring at 100 rpm, and at different times, the supernatant was harvested by filtration, and the extracellular lytic activity was determined by the Nelson method modified by Somogy, as well as the extracellular protein by the Lowry method.
 Results: The production of extracellular polygalacturonase and xylanase was induced, finding that the former has an optimal induction time at 7 days, with glutamic acid as a nitrogen source, and is stable at 4°C and 28°C and an optimal temperature and activity times of 60-80°C and 4 hours, while xylanase presents an optimal induction time of 9 days, with glutamic acid as nitrogen source, and very stable at 4 and 28°C, with optimal temperature and time of activity of 28°C and 8 hours.
 Conclusion: The fungus exhibits both polygalacturonase and xylanase activity. The polygalacturonase activity has a maximum induction time at 7 days, while xylanase has an optimal induction time at 9 days of incubation at 28°C. The xylanase activity was very stable at 4°C and 28°C, as it retains an activity of 100% at both temperatures after five days of incubation, while polygalacturonase retains 82.5% of its initial activity at 4°C, and 56.7% at 28°C.

A Comparison of the Performance of the Midarm Circumference and the Nelson Weight Estimation Formulas in Nigerian Children

Background: In emergencies, two commonly used weight estimation methods are Nelson and mid-arm circumference (MAC)-based formulae. Nelson's method requires the child's age while the MAC formula offers weight estimation without any prior details of the child, which is useful in our environment due to the lack of proper vital statistics documentation. Methodology: We measured the weight, height, and MAC of 1390 children aged 1–12 years. Values got from the measurements were substituted in MAC and Nelson formulae for weight estimation. The estimated weights were compared to the actual weights of the children. Results: A total of 1390 children were enrolled. The mean of enrolled children's actual weight was significantly higher than the mean weight estimated using MAC and Nelson formula. MAC method overestimated weight in children 1–7 years and underestimated weight in those 8–12 years old. On the other hand, the Nelson formula underestimated weights in children 2–11 years and overestimated weight in 1 and 12-year olds. Conclusions: Both the MAC and Nelson method have their deficiencies in weight estimation. Though the Nelson formula appears slightly more accurate than the MAC, weight estimates from both methods were mostly within the actual weight agreement limits.

The Sensitivity Test of Mycobacterium tuberculosis to Snail Seromucoid and Chitosan in vitro

Tuberculosis (TB) is an infection caused by M. tuberculosis (MTb) and is transmitted through droplets of phlegm in the air from patients or those suspected of having TB. In general, treatment for TB is done with anti-tuberculosis drugs (ATDs), specifically streptomycin, isoniazid, rifampicin, and ethambutol (SIRE) that takes a long time due to the level of resistance of MTb bacteria. The resistance of MTb triggers ATDs based on natural bioactive compounds. Chitosan as a result of chitin deacetylation can function as an antimicrobial agent because it is polycationic, which is biodegradable, biocompatible, and non-toxic. Snail (Achatina fulica) seromucoid contains antibacterial bioactive compounds, namely glycans, peptides, glycopeptides, achasin protein, and chondroitin sulfate. This study aims at testing the sensitivity of MTb isolates against snail seromucoid and chitosan in vitro. This research applied the experimental research method. MTb isolates were obtained from sputum samples of patients suspected of TB at the Surakarta Regional Public Hospital (RSUD Surakarta). The results of screening for MTb were positive, based on the microscopic examination of MTb using the Ziehl Nelson (ZN) method, the MPT 64 rapid test, and the quick molecular test using the Genexpert method. The research was completed through several stages, including the preparation of a suspension of germs with a concentration of 1 mg/ml or Mc. Farland 0.5-1.0; preparation of the stock solution and working solution (WS); drug sensitivity test (DST) against snail seromucoid; chitosan and ATDs (SIRE) on Lowenstein Jensen (LJ) media; and incubation at 37°C for 3-4 weeks. The results were interpreted on day 28 or day 42. The results have revealed that MTb isolates are 100% resistant to snail seromucoid and 2% chitosan. This study concludes that MTb isolates from suspected TB are resilient to 100% snail seromucoid and 2% chitosan.

Narrativity and Referential Activity Predict Episodic Memory Strength in Autobiographical Memories.

Narrativity has been proposed as an indicator of episodic memory strength when people discuss their past (Nelson and Horowitz in Discourse Processes 31:307-324, 2001. https://doi.org/10.1207/S15326950dp31-3_5 ). Referential Activity, the extent to which words convey a speaker's experience of being present in the event being described, has been independently hypothesized to indicate episodic memory strength (Maskit inJ Psycholinguist Res, 2021. https://doi.org/10.1007/s10936-021-09761-8 ). These hypotheses are tested using a linguistic measure of narrativity and a computerized measure of referential activity to predict previous independent ratings of episodic memory strength that usedthe Levine et al. (Psychol Aging 17(4):677-689, 2002. https://doi.org/10.1037//0882-7974.17.4.677 ) measure of internal details in retold personal memories provided by Schacter (Addis et al. in Psychol Sci 19(1):33-41, 2008. https://doi.org/10.1111/j.1467-9280.2008.02043.x ). Raters scored narrativity on four brief near and far past memories elicited from 32 subjects, using Nelson's narrative temporal sequence method based on Labov's (J Narrat Life Hist 7(1-4):395-415, 1997. https://doi.org/10.1075/jnlh.7.49som ) analysis of spoken narratives of personal experience; computerized weighted scores of referential activity (WRAD) were obtained on these same 128 memories. Data analysis showed that narrative temporal sequences predict internal details and WRAD predict internal details. Adding WRAD to narrative temporal sequences improved the prediction of internal details.

Is the Lack of Response of Maize to Fertilization in Soils with Low Bray1-P Related to Labile Organic Phosphorus?

The usual soil test phosphorus (P) neglects the P supply from labile organic P (Po) fractions, which could explain the nonresponse of maize (Zea mays L.) in sites with soil P testing below the critical level. We aim to determine Po and inorganic P (Pi) in NaHCO3 extracts and in the coarse soil fraction (hereinafter, CF) from responsive and nonresponsive sites to P fertilization in maize. We then compare the classification errors of the Cate and Nelson method by comparing the relationship between maize relative yield and the soil Bray1-P concentration vs. the new proposed indices. The study included responsive and nonresponsive sites to P fertilization carried out across the Pampas Region in the center-east of Argentina. Treatments included four P fertilization rates: 0, 12, 24, and 36 kg P ha−1. The experiments were laid out in a randomized complete block design with three replicates. We determined Bray1-P, Pi, and Po in NaHCO3 extracts and in the coarse soil fraction. Sites non-responsive to P fertilization and with Bray1-P concentrations below the critical level showed 70% more Po in the coarse soil fraction (Po-CF) than sites with high crop response and similar Bray1-P level. However, Po-Bic alone did not improve the relationship with maize relative yield. Po-CF and Bray1-P included in a soil integrative P index improved the prediction of crop response to P fertilization and reduced classification errors, which suggests that Po-CF is a source of available P for the crops. The novelty reported in this study was to demonstrate the organic P contribution to relative yield by including it into an integrative soil testing. We find that nonresponsive sites to P fertilization, with low Bray1-P, were correctly classified when including Po-CF in a new soil test P. Improvements in the P fertilization diagnostic prescription tool contribute to an increase in economic profit and reduce environmental impact.

Comparison of age-based weight estimation with actual measured weight in children aged one to twelve years in Enugu.

This study was carried out to evaluate the degree of accuracy of age-based weight estimation methods in assessing the weight of the Nigerian child. The weights of one thousand, four hundred and fifty-six (1,456) children were measured and compared with the updated Advanced Paediatric Life Support (APLS), Best guess, Nelson and Luscombe & Owen methods. The updated APLS, Nelson and Luscombe & Owen methods underestimated the weights in younger children while overestimating in older ones. Best guess overestimated the weights across all ages. The Nelson formula had the best agreement within 10% and 20% of the measured weights among all methods. A linear regression analysis produced an equation for weight estimation: weight (W) = 2.058 Y + 9.925, where W is weight in kilogram and Y is the age in years. None of the weight estimation formulae assessed was entirely accurate in our study, though the Nelson method showed superior agreement.

Critical Level Determination of Phosphorus for Big Red Chili (Capsicum annuum L.) Growth on Soil in Java Island

Salah satu upaya yang dapat dilakukan agar pemupukan fosfor (P) sesuai dengan kebutuhan tanaman cabai merah besar ialah dengan melakukan analisis tanah serta menentukan batas kritis P di tanah yang dihubungkan dengan produksi. Tujuan dari penelitian ini adalah menentukan batas kritis P di tanah untuk tanaman cabe merah besar di Pulau Jawa. Contoh tanah diambil dari 19 lokasi yang tersebar di Pulau Jawa. Analisis P tanah sebelum tanam dilakukan dengan tiga metode ekstraksi P yaitu Bray 1, Olsen, dan Mehlich III. Setelah analisis P tanah, bibit cabe merah besar ditanam dalam pot yang berisi 500 g tanah berat kering mutlak untuk tiap lokasi dan tiap lokasi mempunyai 4 dosis pemupukan. Dosis pemupukan P terdiri dari 0, 55, 110, dan 220 kg ha-1 P2O5. Sebagai pupuk dasar juga diberikan pupuk urea dan KCl masing-masing dengan dosis 110 kg ha-1 dan 180 kg ha-1. Tiap tanaman dipanen biomassanya setelah berumur 4 minggu setelah tanam. Pengaruh pupuk P terhadap parameter pertumbuhan tanaman dievaluasi menggunakan analisis ragam. Batas kritis P tanah ditetapkan dengan metode Cate dan Nelson. Hasil menunjukkan bahwa pemberian pupuk P berpengaruh nyata terhadap tinggi tanaman, bobot basah dan bobot kering tanaman. Pemupukan 220 kg ha-1 P2O5 memberikan respon tertinggi terhadap parameter pertumbuhan tanaman. Hasil uji korelasi menunjukkan bahwa ketiga metode ekstraksi P tersebut berkorelasi positif dan nyata dengan bobot kering tanaman. Metode ekstraksi Olsen memiliki korelasi tertinggi dengan bobot kering tanaman (r = 0.665). Batas kritis P dalam tanah untuk tanaman cabai merah besar di pulau Jawa berdasarkan metode ekstraksi Bray 1, Olsen, dan Mehlich III masing-masing ialah 15 ppm, 40 ppm, dan 50 ppm.
 Kata kunci: analisis tanah, Bray 1, Cate dan Nelson, Mehlich, metode ekstraksi, Olsen

Effect of a Shift in Diurnal Geomagnetic Variation on the Activity and Sensitivity of Digestive Glycosidases in Roach Underyearlings to Heavy Metals

The effect of temporal shifts in diurnal geomagnetic variation with 6- and 12-h intervals relative to the day–night cycle on the activity of digestive glycosidases (maltase and amylolytic activity) and their sensitivity to the in vitro influence of heavy metal ions (Cu2+, Zn2+, Pb2+, Cd2+) at a concentration of 25 mg/L has been studied in roach Rutilus rutilus (L.) underyearlings. Amylolytic activity (the total activity of starch-hydrolyzing enzymes: α-amylase, glucoamylase, and maltase) is determined by the modified Nelson method, maltase activity by the glucoseoxidase method with a Fotoglukoza clinical biochemistry kit. It is found that exposing embryos to both 6- and 12-h shifts in diurnal geomagnetic variation reduces the activity of maltase and its sensitivity to the effect of zinc and cadmium ions. Amylolytic activity increases only in roach underyearlings exposed to a 6-h shift in diurnal geomagnetic variation as embryos. The sensitivity of starch-hydrolyzing enzymes to the influence of copper (6- and 12-h shifts) and cadmium (12-h shift) increases. The decrease in the enzyme activity and its increased sensitivity to the inhibitory effect of heavy metals may reduce the efficiency of carbohydrate hydrolysis in roach underyearlings. The increase in the amylolytic activity can be considered as adaptation of the digestive system of the fish to a 6-h shift in diurnal geomagnetic variation relative to the day–night cycle during embryogenesis.

Adverse Event Profile Associated with Prolonged Use of CentriMag Ventricular Assist Device for Refractory Cardiogenic Shock.

Several studies have investigated early outcomes with a surgical short-term ventricular assist device (VAD), but little is known about adverse event profile during prolonged support with a surgical short-term VAD. This is a retrospective analysis of 161 patients who received a CentriMag ventricular assist system (Abbott Laboratories, Abbott Park, IL) at our institution between January 2007 and June 2014. Device-related adverse events include major bleeding, infection, and stroke incidents occurring during CentriMag support. Cumulative frequency of adverse events was estimated by Nelson's nonparametric method. One hundred and forty-three (88.8%) patients had biventricular VAD and 18 (11.2%) had isolated left VAD. Median duration of support was 16 days (interquartile range [IQR]: 10-29). Mortality was 24.8% and 1 year overall survival is 51.8% (95% CI: 43.3-59.5%). The most common adverse event during support was major bleeding (n = 121, 75.1%). Ninety-five (59.0%) developed major infections such as pneumonia and urinary tract infection. Sixteen patients (10%) experienced stroke. Cumulative data analysis showed that stroke and reoperation caused by bleeding were rare beyond 30 days, whereas infection and nonsurgical bleeding events were directly related to support time. In conclusion, temporary VAD with CentriMag support is an effective treatment for patients in refractory cardiogenic shock. Despite its side effect, profile including a high rate of blood transfusion early in the immediate postoperative period of CentriMag support, aggressive use of the CentriMag support device has acceptable survival to discharge and 1 year survival.

Utilization of Rice Straw Hydrolysis Product of Penicillium sp. H9 as A Substrate of Biosurfactant Production by LII61 Hydrocarbonoclastic Bacteria

This study aims to reveal the prospect of rice straw as a biosurfactant production substrate by hydrocarbonoclastic bacteria. Rice straw can be hydrolysed enzymatically into simple sugar by Penicillium sp. H9. Hydrolysis products are used as growth medium and biosurfactant production by LII61 bacteria. The concentration sugar from hydrolysis product was analyzed by Nelson method. In this study, molasses were used as a comparison substrate in biosurfactant production. The growth response of LII61 bacteria was observed by measuring the turbidity of the culture. Biosurfactant products were evaluated by measuring the emulsification activity (%) and surface tension (mN/m). Acquisition of sugar from rice straw hydrolysis product (RSHP) was 209.25 μg/mL. The optimum growth both of RSHP and molasses substrates were obtained on the 5th day of incubation with a culture turbidity value of ODλ650 0.201 and ODλ650 0.157 respectively. The lowest surface tension obtained in culture of RSHP was 48.85 mN/m. It was better than biosurfactant product on the molasses substrate on the 3rd day incubation. However, during the incubation time both substrates did not show emulsification activity. Biosurfactants produced have certain characteristics on variations in pH and temperature.

Sufficiency ranges for lemon balm and nutrient removals in aboveground phytomass

ABSTRACTA set of fertilizer experiments were conducted during three growing seasons with the aim of establishing sufficiency ranges and crop nutrient removals for Melissa officinalis L. Critical nutrient concentrations were determined by the Cate–Nelson method or by removing 10% of extreme high and low values, respectively if a positive response to a given nutrient was recorded or not. Sufficiency ranges for macro, micronutrients, and SPAD-readings were set as: 27.0–40.0 g N kg−1; 0.8–2.7 g P kg−1 (May–August); 1.5–3.8 g P kg−1 (September–November); 10.0–25.0 g K kg−1 (May–August); 18.0–32.0 g K kg−1 (September–November); 5.0–25.0 g Ca kg−1; 3.5–8.5 g Mg kg−1; 18–125 mg B kg−1; 5–25 mg Cu kg−1; 75–500 mg Fe kg−1; 20–300 mg Zn kg−1; 30–250 g Mn kg−1; 30–45 SPAD-units. These results will allow laboratories to use plant analysis as an important tool in improving the fertilizer recommendations for this species.

Study of Reversible CD4/CD8+ve T Cell Counts in Patients with HIV Negative Pulmonary Tuberculosis after Effective Treatment with Antitubercular Therapy (ATT)

Background/Purpose: Tuberculosis (T.B) an infectious disease caused by Mycobacterium tuberculosis is still one of the biggest killers among the infectious diseases. Immunological deficiencies of various magnitudes have been reported in TB which include CD4 + T and CD8 + T cells. The aim of the study was investigating the at the occurrence of CD4+ T cell lymphopenia in patients with active pulmonary tuberculosis and the response of this abnormality to ATT in HIV negative patients. Methods: The study subjects included three groups in which 30 patients were with sputum positive pulmonary tuberculosis without any evidence of HIV infection and second group of10 healthy controls. Third group included10 patients with pulmonary tuberculosis co-infected HIV sero-positivity. Zeil Nelson (ZN) method was used to diagnose pulmonary tuberculosis, ELISA method was adopted to confirm the HIV status and CD4 and CD8 count was done by flow cytometry. Results: The CD­4 + T cell lymphopenia was observed significantly associated (p=0.000) in Non-HIV pulmonary tuberculosis cases as compared to controls (370.87 ± 209.00 cells/μl v/s 673.60 ± 120.30 cells/μl).CD4 + T cell lymphopenia was significantin HIV positive pulmonary TB patients compared to healthy controls (p=0.000). CD4 + T cell lymphopenia was more severe in HIV co-infected pulmonary tuberculosis patients compared to Non-HIV pulmonary TB cases (p=0.029). Conclusion: We conclude that the pulmonary tuberculosis is an important cause of non HIV CD4, CD8 lymphopenia, with reversal of CD4/CD8 ratio, and this is reversible with effective treatment with antitubercular therapy (ATT).

Sensitivity reanalysis of vibration problem using combined approximations method

Sensitivity is indispensable to structural modification and optimization. This paper focuses on the analytical sensitivity reanalysis for vibration problem in the framework of combined approximations (CA) method. The sensitivity reanalysis formulations of eigenvalues and eigenvectors are derived from the vibration equation reduced by CA method, where the eigenvector sensitivity is solved by Nelson's method. Numerical examples demonstrate the accuracy and efficiency of the proposed reanalysis method. Especially, this method can greatly improve the efficiency of sensitivity analysis and can accelerate the gradient-based structural optimization constrained with frequencies and modal shapes.

Comparative evaluation of rivastigmine permeation from a transdermal system in the Franz cell using synthetic membranes and pig ear skin with in vivo-in vitro correlation

In the present study, in vitro permeation experiments in a Franz diffusion cell were performed using different synthetic polymeric membranes and pig ear skin to evaluate a rivastigmine (RV) transdermal drug delivery system. In vitro-in vivo correlations (IVIVC) were examined to determine the best model membrane. In vitro permeation studies across different synthetic membranes and skin were performed for the Exelon® Patch (which contains RV), and the results were compared. Deconvolution of bioavailability data using the Wagner–Nelson method enabled the fraction of RV absorbed to be determined and a point-to-point IVIVC to be established. The synthetic membrane, Strat-M™, showed a RV permeation profile similar to that obtained with pig ear skin (R2=0.920). Studies with Strat-M™ resulted in a good and linear IVIVC (R2=0.991) when compared with other synthetic membranes that showed R2 values less than 0.90. The R2 for pig ear skin was 0.982. Strat-M™ membrane was the only synthetic membrane that adequately simulated skin barrier performance and therefore it can be considered to be a suitable alternative to human or animal skin in evaluating transdermal drug transport, potentially reducing the number of studies requiring human or animal samples.

Adsorption of U (VI) ions from aqueous solution using silicon dioxide nanopowder

The adsorption kinetics for removal of uranium (V1) from aqueous solution using silicon dioxide nanopowder (nano-SiO2) was investigated in batch and continuous techniques. Pseudo-first order and pseudo-second order were used to analyze the kinetics of batch experiments. In continuous technique the important parameters (initial concentration, flow rate and bed height) on the breakthrough curves were studied and the adsorption kinetics was analyzed using Thomas and Yoon and Nelson kinetic models. The comparison between the kinetic models was evaluated by the correlation coefficients (r2). The results indicated that the batch experiments fitted well with pseudo second-order kinetic model. The comparison of the experimental breakthrough curve to the breakthrough profile obtained from Thomas and Yoon and Nelson methods showed a satisfactory fit for silicon dioxide nanopowder.