Journal articles on the topic 'PH Weibull model'
To see the other types of publications on this topic, follow the link: PH Weibull model.
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 journal articles for your research on the topic 'PH Weibull model.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.
1
Tsai, Bor-Wen, John T. Harvey, and Carl L. Monismith. "Application of Weibull Theory in Prediction of Asphalt Concrete Fatigue Performance." Transportation Research Record: Journal of the Transportation Research Board 1832, no. 1 (January 2003): 121–30. http://dx.doi.org/10.3141/1832-15.
Full textAbstract:
The objectives are to present the feasibility of utilizing the Weibull proportional hazards (PH) model and the Weibull accelerated failure time model of survival analysis to predict in situ pavement fatigue performance from laboratory fatigue test results. A set of WesTrack temperature sensitivity fatigue tests is used as an example to demonstrate how the Weibull PH model works. An example utilizing the deflection data from a heavy vehicle simulator test is given to verify the feasibility of the failure time model. The relationship between mode factor and controlled-deformation fatigue test is discussed using the same example. The Weibull theory approach has potential for use in recursive mechanistic-empirical design procedures.
2
BLACK, D. GLENN, X. PHILIP YE, FEDERICO HARTE, and P. MICHAEL DAVIDSON. "Thermal Inactivation of Escherichia coli O157:H7 When Grown Statically or Continuously in a Chemostat." Journal of Food Protection 73, no. 11 (November 1, 2010): 2018–24. http://dx.doi.org/10.4315/0362-028x-73.11.2018.
Full textAbstract:
The objective of this study was to determine if survivor curves for heat-inactivated Escherichia coli O157:H7 were affected by the physiological state of the cells relative to growth conditions and pH of the heating menstruum. A comparison was made between the log-linear model and non–log-linear Weibull approach. Cells were grown statically in aerobic culture tubes or in an aerobic chemostat in tryptic soy broth (pH 7.2). The heating menstruum was unbuffered peptone or phosphate buffer (pH 7.0). Thermal inactivation was carried out at 58, 59, 60, and 61°C, and recovery was on a nonselective medium. Longer inactivation times for statically grown cells indicated potential stress adaptation. This was more prevalent at 58°C. Shape response was also significantly different, with statically grown cells exhibiting decreasing thermal resistance over time and chemostat cells showing the opposite effect. Buffering the heating menstruum to ca. pH 7 resulted in inactivation curves that showed less variability or scatter of data points. Time to specific log reduction values (td) for the Weibull model were conservative relative to the log-linear model depending upon the stage of reduction. The Weibull model offered the most accurate fit of the data in all cases, especially considering the log-linear model is equivalent to the Weibull model with a fixed shape factor of 1. The determination of z-value for the log-linear model showed a strong correlation between log D-value and process temperature. Correlations for the Weibull model parameters (log δand log p) versus process temperature were not statistically significant.
3
Mestre, Luis, David Allison, Keisuke Ejima, Nianjun Liu, and Greg Pavela. "Determining an Appropriate Statistical Model when Assessing the Association between Obesity and Mortality." Current Developments in Nutrition 6, Supplement_1 (June 2022): 38. http://dx.doi.org/10.1093/cdn/nzac047.038.
Full textAbstract:
Abstract Objectives To determine a statistical model appropriate to assess the association between Obesity and mortality using epidemiological data. We hypothesized that the model with the lowest AIC, BIC, and lowest Sobol's Indices is the appropriate model, compared to the others, to assess the association between obesity and mortality. Methods The datasets used were the National Child Development Study, the Health Retirement Study, the National Health Interview Survey, and the National Health and Nutrition Examination Survey. The statistical models compared were the Cox PH Model and the AFT Model. For the AFT Model, we used the Weibull Distribution, Lognormal Distribution, and Exponential Distribution. Body mass index (BMI) was used as a proxy for obesity, the exposure of interest. Mortality, the event of interest, was calculated using age and a death indicator of the participants. Covariates were sex, socioeconomic status (SES), education, smoking status, drinking status. The interactions were between BMI and SES, BMI and Sex, BMI and Smoking Status. Results The results of the NCDS dataset indicated that the Cox PH Model has an AIC of 11528.81, BIC of 11611.81 without interactions, an AIC of 11502.04, and BIC of 11640.36 with interaction. The Cox PH model has the highest AIC and BIC regardless of the inclusion of interactions compared to the AFT Models. The AFT model with a Weibull distribution had the lowest AIC and BIC (without interaction: 8367.61 and 8521.30, respectively and with interaction: 8346.29 and 8592.19, respectively). The Sobol's Indices for the models, without interaction, were close to zero for all covariates except education, where all models were close to one. However, with interactions, the Sobol's Indices of the education covariate decreases for all AFT Models though the Cox PH Model remains the highest and without change. Conclusions Given our sample and specified model, the AFT model with a Weibull distribution appeared to fit the data better relative to the Cox PH Model or the other AFT Models. The Cox PH model is more sensitive to interactions than the AFT Models. Funding Sources National Institute of Aging (NIA): 3R01AG057703-02S1
4
Koseki, Shige, Yasuko Mizuno, and Itaru Sotome. "Modeling of Pathogen Survival during Simulated Gastric Digestion." Applied and Environmental Microbiology 77, no. 3 (December 3, 2010): 1021–32. http://dx.doi.org/10.1128/aem.02139-10.
Full textAbstract:
ABSTRACTThe objective of the present study was to develop a mathematical model of pathogenic bacterial inactivation kinetics in a gastric environment in order to further understand a part of the infectious dose-response mechanism. The major bacterial pathogensListeria monocytogenes,Escherichia coliO157:H7, andSalmonellaspp. were examined by using simulated gastric fluid adjusted to various pH values. To correspond to the various pHs in a stomach during digestion, a modified logistic differential equation model and the Weibull differential equation model were examined. The specific inactivation rate for each pathogen was successfully described by a square-root model as a function of pH. The square-root models were combined with the modified logistic differential equation to obtain a complete inactivation curve. Both the modified logistic and Weibull models provided a highly accurate fitting of the static pH conditions for every pathogen. However, while the residuals plots of the modified logistic model indicated no systematic bias and/or regional prediction problems, the residuals plots of the Weibull model showed a systematic bias. The modified logistic model appropriately predicted the pathogen behavior in the simulated gastric digestion process with actual food, including cut lettuce, minced tuna, hamburger, and scrambled egg. Although the developed model enabled us to predict pathogen inactivation during gastric digestion, its results also suggested that the ingested bacteria in the stomach would barely be inactivated in the real digestion process. The results of this study will provide important information on a part of the dose-response mechanism of bacterial pathogens.
5
Dufort, Evann L., Jonathan Sogin, Mark R. Etzel, and Barbara H. Ingham. "Inactivation Kinetics of Pathogens during Thermal Processing in Acidified Broth and Tomato Purée (pH 4.5)." Journal of Food Protection 80, no. 12 (November 1, 2017): 2014–21. http://dx.doi.org/10.4315/0362-028x.jfp-17-147.
Full textAbstract:
ABSTRACT Thermal inactivation kinetics for single strains of Shiga toxin–producing Escherichia coli (STEC), Listeria monocytogenes, and Salmonella enterica were measured in acidified tryptic soy broth (TSB; pH 4.5) heated at 54°C. Inactivation curves also were measured for single-pathogen five-strain cocktails of E. coli O157:H7, L. monocytogenes, and S. enterica heated in tomato purée (pH 4.5) at 52, 54, 56, and 58°C. Inactivation curves were fit using log-linear and nonlinear (Weibull) models. The Weibull model yields the time for a 5-log reduction (t*) and a curve shape parameter (β). Decimal reduction times (D-values) and thermal resistance constants (z-values) from the two models were compared by defining t* = 5D* for the Weibull model. When the log-linear and Weibull models match at the 5-log reduction time, then t* = 5D* = 5D and D = D*. In 18 of 20 strains heated in acidified TSB, D and D* for the two models were not significantly different, although nonlinearity was observed in 35 of 60 trials. Similarly, in 51 of 52 trials for pathogen cocktails heated in tomato purée, D and D* were not significantly different, although nonlinearity was observed in 31% of trials. At a given temperature, D-values for S. enterica << L. monocytogenes < E. coli O157:H7 in tomato purée (pH 4.5). When using the two models, z-values calculated from the D-values were not significantly different for a given pathogen. Across all pathogens, z-values for E. coli O157:H7 and S. enterica were not different but were significantly lower than the z-values for L. monocytogenes. These results are useful for supporting process filings for tomato-based acidified food products with pH 4.5 and below and are relevant to small processors of tomato-based acidified canned foods who do not have the resources to conduct research on and validate pathogen lethality.
6
Zhang, Zedi, Yuhua Lei, Xiaohong Yang, Nana Shi, Lina Geng, Shuping Wang, Jianjun Zhang, and Shikao Shi. "High drug-loading system of hollow carbon dots–doxorubicin: preparation, in vitro release and pH-targeted research." Journal of Materials Chemistry B 7, no. 13 (2019): 2130–37. http://dx.doi.org/10.1039/c9tb00032a.
Full text
7
Hosein, Althea M., Frederick Breidt, and Charles E. Smith. "Modeling the Effects of Sodium Chloride, Acetic Acid, and Intracellular pH on Survival ofEscherichia coliO157:H7." Applied and Environmental Microbiology 77, no. 3 (November 29, 2010): 889–95. http://dx.doi.org/10.1128/aem.02136-10.
Full textAbstract:
ABSTRACTMicrobiological safety has been a critical issue for acid and acidified foods since it became clear that acid-tolerant pathogens such asEscherichia coliO157:H7 can survive (even though they are unable to grow) in a pH range of 3 to 4, which is typical for these classes of food products. The primary antimicrobial compounds in these products are acetic acid and NaCl, which can alter the intracellular physiology ofE. coliO157:H7, leading to cell death. For combinations of acetic acid and NaCl at pH 3.2 (a pH value typical for non-heat-processed acidified vegetables), survival curves were described by using a Weibull model. The data revealed a protective effect of NaCl concentration on cell survival for selected acetic acid concentrations. The intracellular pH of anE. coliO157:H7 strain exposed to acetic acid concentrations of up to 40 mM and NaCl concentrations between 2 and 4% was determined. A reduction in the intracellular pH was observed for increasing acetic acid concentrations with an external pH of 3.2. Comparing intracellular pH with Weibull model predictions showed that decreases in intracellular pH were significantly correlated with the corresponding times required to achieve a 5-log reduction in the number of bacteria.
8
Sharma, Reema, Richa Srivastava, and Satyanshu K. Upadhyay. "A Hierarchical Bayes Analysis and Comparison of PH Weibull and PH Exponential Models for One-Shot Device Testing Experiment." International Journal of Reliability, Quality and Safety Engineering 28, no. 05 (July 30, 2021): 2150036. http://dx.doi.org/10.1142/s0218539321500364.
Full textAbstract:
The one-shot devices are highly reliable and, therefore, accelerated life tests are often employed to perform the experiments on such devices. Obviously, in the process, some covariates are introduced. This paper considers the proportional hazards model to observe the effect of covariates on the failure rates under the assumption of two commonly used models, namely the exponential and the Weibull for the lifetimes. The Bayes implementation is proposed using the hybridization of Gibbs and Metropolis algorithms that routinely extend to missing data situations as well. The entertained models are compared using the Bayesian and deviance information criteria and the expected posterior predictive loss criterion. Finally, the results based on two real data examples are given as an illustration.
9
Jajang, Jajang, Raden Ninditya Ghina Ashfahani, Agustini Tripena Br.Sb, and Nunung Nurhayati. "MODEL SURVIVAL SEMIPARAMETRIK DAN PARAMETRIK UNTUK DATA DEMAM BERDARAH DENGUE (DBD) DI RSUD KABUPATEN CIAMIS TAHUN 2020." JST (Jurnal Sains dan Teknologi) 11, no. 2 (August 15, 2022): 419–25. http://dx.doi.org/10.23887/jstundiksha.v11i2.43493.
Full textAbstract:
The research is about the best survival analysis model used for patients with Dengue Hemorrhagic Fever (DHF) at Ciamis Hospital in 2020. The purpose of this research is to identify the factors that influence the rate of cure for DHF at Ciamis Hospital in 2020. The method used is survival analysis. Furthermore, the parametric model used Weibull PH, whereas the semiparametric model used Cox PH regression. The result of the analysis showed that the best model obtained was the semiparametric Cox PH regression model, with significant factors including age, Pack Cell Volume (PCV), hemoglobin, White Blood Cell (WBC), and body temperature.
10
HU, XIAOPEI, PARAMESWARAKUMAR MALLIKARJUNAN, JAHEON KOO, LINDA S. ANDREWS, and MICHAEL L. JAHNCKE. "Comparison of Kinetic Models To Describe High Pressure and Gamma Irradiation Used To Inactivate Vibrio vulnificus and Vibrio parahaemolyticus Prepared in Buffer Solution and in Whole Oysters." Journal of Food Protection 68, no. 2 (February 1, 2005): 292–95. http://dx.doi.org/10.4315/0362-028x-68.2.292.
Full textAbstract:
Comparisons of different models in inactivation kinetics were conducted on data obtained from high-pressure and gamma-irradiation processing. Vibrio vulnificus (MO-624) and Vibrio parahaemolyticus (O3:K6 TX-2103) suspended in phosphate-buffered saline (pH 7.4, 107 CFU/ml) were exposed to pressures from 207 to 379 MPa for 1 to 20 min. Inoculated whole oysters (106 CFU/g) were exposed to pressure from 276 to 379 MPa for 1 to 15 min. Pure cultures and inoculated oysters (106 CFU/g) also were irradiated (gamma irradiation) at doses of less than 3 kGy. Four mathematical models, the Bigelow model, Arrhenius equation, Fermi equation, and Weibull frequency distributions, were applied to microbial survival data, and performances of the different kinetic models were compared. Weibull frequency distributions can predict the high-pressure inactivation of Vibrio spp. with more accuracy in both pure cultures and inoculated oyster samples. The Fermi model provided a better description of gamma-irradiation inactivation kinetics compared with the traditional Bigelow model.
11
Ghofrani, Faeze, Qing He, Reza Mohammadi, Abhishek Pathak, and Amjad Aref. "Bayesian Survival Approach to Analyzing the Risk of Recurrent Rail Defects." Transportation Research Record: Journal of the Transportation Research Board 2673, no. 7 (May 2, 2019): 281–93. http://dx.doi.org/10.1177/0361198119844241.
Full textAbstract:
This paper develops a Bayesian framework to explore the impact of different factors and to predict the risk of recurrence of rail defects, based upon datasets collected from a US Class I railroad between 2011 and 2016. To this end, this study constructs a parametric Weibull baseline hazard function and a proportional hazard (PH) model under a Gaussian frailty approach. The analysis is performed using Markov chain Monte Carlo simulation methods and the fit of the model is checked using a Cox–Snell residual plot. The results of the model show that the recurrence of a defect is correlated with different factors such as the type of rail defect, the location of the defect, train speed limit, the number of geometry defects in the last three years, and the weight of the rail. First, unlike the ordinary PH model in which the occurrence times of rail defects at the same location are assumed to be independent, a PH model under frailty induces the correlation between times to the recurrence of rail defects for the same segment, which is essential in the case of recurrent events. Second, considering Gaussian frailties is useful for exploring the influence of unobserved covariates in the model. Third, integrating a Bayesian framework for the parameters of the Weibull baseline hazard function as well as other parameters provides greater flexibility to the model. Fourth, the findings are useful for responsive maintenance planning, capital planning, and even preventive maintenance planning.
12
Chambi Rodriguez, Alex Danny, and Ana Mónica Torres Jiménez. "Modelos cinéticos sigmoidales aplicados al crecimiento de Saccharomyces boulardii." Revista de Investigaciones Altoandinas - Journal of High Andean Research 23, no. 1 (January 15, 2021): 47–54. http://dx.doi.org/10.18271/ria.2021.213.
Full textAbstract:
Predictive microbiology is an interesting tool that allows evaluating the behavior of biomass and metabolites in different culture media, providing multiple benefits, whether scientific or industrial, for these and other reasons the objective of this research was to evaluate applied sigmoidal kinetic models to the growth of Saccharomyces boulardii in milk. For this purpose, flasks were prepared with 200 mL of fresh cow's milk, previously sterilized at 121 ° C x 15 min, then the strains were inoculated at a temperature of 37 ° C and incubated at the same temperature under constant shaking of 20 revolutions per minute (rpm) in a water bath with shaking, for 7 h; To construct the curves and obtain the growth constants, colony-forming units were counted per milliliter (cfu / ml) at one-hour intervals, with a monocular microscope and Neubauer chamber. Also, the pH and titratable acidity expressed in lactic acid were measured. The data obtained were converted to a logarithmic scale to apply the sigmoidal equations of Gompertz, Logistic, Modified Logistic and Weibull. The results of the kinetic modeling gave us that the modified Logistics and Logistics models presented a better fit compared to the rest. Likewise, the Weibull model presented the lowest value of adjustment, on the other hand, in the analysis of the statistical criteria, all models except Weibull present similarity. Finally, each sigmoidal model allowed to evaluate the growth of Saccharomyces boulardii with each of its kinetic constants.
13
Costa, André Lima de Oliveira, Paula Cristina Rezende Enéas, Tiago Assis Miranda, Sueli Aparecida Mingoti, Cristina Duarte Vianna Soares, and Gerson Antônio Pianetti. "In vitro dissolution kinetic for mycophenolic acid derivatives tablets." Brazilian Journal of Pharmaceutical Sciences 49, no. 2 (June 2013): 311–19. http://dx.doi.org/10.1590/s1984-82502013000200013.
Full textAbstract:
Mycophenolate mofetil (MMF) and mycophenolate sodium (MPS) are an ester and a salt of mycophenolic acid. They have different kinetic in vivo characteristics due to differences in molecular structures, physicochemical properties and formulations administered. In this study, dissolution profiles of reference products were tested in different media to evaluate the effect of pH, kinetic dissolution and the best statistical model that can be used to predict the release of both drugs. The drug release was determined by using a validated ultraviolet spectrophotometry method, λ 250 nm. The method showed to be selective, linear, precise and accurate for MMF in 0.1 M HCl and MPS in sodium phosphate buffer pH 6.8. Dissolution kinetics models of zero order, first order, Higuchi, Hixson-Crowell and Weibull were applied to data in order to select the best fit by linear regression. The regression parameters were estimated and the models were evaluated with the results of residuals and coefficient of determination. The residuals obtained from dissolution kinetics models were random, uncorrelated, and normally distributed with constant variance. The R² values (74.7% for MMF and 95.8% for MPS) demonstrated good ability of the Weibull regression to explain the variability and to predict the drugs' release.
14
COLLADO, J., A. FERNÁNDEZ, L. M. CUNHA, M. J. OCIO, and A. MARTÍNEZ. "Improved Model Based on the Weibull Distribution To Describe the Combined Effect of pH and Temperature on the Heat Resistance of Bacillus cereus in Carrot Juice†‡." Journal of Food Protection 66, no. 6 (June 1, 2003): 978–84. http://dx.doi.org/10.4315/0362-028x-66.6.978.
Full textAbstract:
The effect of pH and temperature on the thermal inactivation of different strains of Bacillus cereus was modeled. Inactivation tests were carried out in carrot broth, following a full factorial design at four levels for temperature (from 90 to 105°C, depending on the strain) and pH (6.2, 5.8, 5.2, and 4.7). Individual inactivation curves were analyzed by applying the Weibull model function (with percent discrepancy close to 20% for most cases), and the effects of pH and temperature on the scale parameter (designated Dβ) and the shape parameter (β) were also studied. Temperature and pH did not have a significant effect on the shape parameter (β). The effect of temperature on the scale parameter was modeled by the z concept. The scale parameter decreased with pH, although the behavior of the strains was not homogeneous. Two global models with a small number of parameters were developed, providing a satisfactory description of the thermal inactivation of B. cereus, with percent discrepancy ranging from 18 to 25%.
15
Concha, Luis, Ana Luiza Resende Pires, Angela Maria Moraes, Elizabeth Mas-Hernández, Stefan Berres, and Jacobo Hernandez-Montelongo. "Cost Function Analysis Applied to Different Kinetic Release Models of Arrabidaea chica Verlot Extract from Chitosan/Alginate Membranes." Polymers 14, no. 6 (March 10, 2022): 1109. http://dx.doi.org/10.3390/polym14061109.
Full textAbstract:
This work focuses on the mathematical analysis of the controlled release of a standardized extract of A. chica from chitosan/alginate (C/A) membranes, which can be used for the treatment of skin lesions. Four different types of C/A membranes were tested: a dense membrane (CA), a dense and flexible membrane (CAS), a porous membrane (CAP) and a porous and flexible membrane (CAPS). The Arrabidae chica extract release profiles were obtained experimentally in vitro using PBS at 37 °C and pH 7. Experimental data of release kinetics were analyzed using five classical models from the literature: Zero Order, First Order, Higuchi, Korsmeyer–Peppas and Weibull functions. Results for the Korsmeyer–Peppas model showed that the release of A. chica extract from four membrane formulations was by a diffusion through a partially swollen matrix and through a water filled network mesh; however, the Weibull model suggested that non-porous membranes (CA and CAS) had fractal geometry and that porous membranes (CAP and CAPS) have highly disorganized structures. Nevertheless, by applying an explicit optimization method that employs a cost function to determine the model parameters that best fit to experimental data, the results indicated that the Weibull model showed the best simulation for the release profiles from the four membranes: CA, CAS and CAP presented Fickian diffusion through a polymeric matrix of fractal geometry, and only the CAPS membrane showed a highly disordered matrix. The use of this cost function optimization had the significant advantage of higher fitting sensitivity.
16
Haefner, James W., and Linda C. Abbott. "Extrapolation of Laboratory pH Dose–Response Data to Fluctuating Environments: Comparisons with a Null Model." Canadian Journal of Fisheries and Aquatic Sciences 46, no. 9 (September 1, 1989): 1499–509. http://dx.doi.org/10.1139/f89-192.
Full textAbstract:
A simple model was developed to extrapolate laboratory dose–response data to randomly varying conditions. We fit published data of dose–response experiments for the effects of low pH stress on survival rates of stream macro-invertebrates to a modification of the Weibull distribution. Using the resulting parameter estimates and Monte Carlo simulation, we compared the values obtained in constant laboratory conditions with the expected survival rates obtained in fluctuating environments. For each of three species, we performed 108 Monte Carlo experiments in a full factorial design that varied the mean pH, the standard deviation of pH fluctuations, the distribution from which pH values were drawn, the distributions of runs of constant pH, and the presence of episodic events. Fluctuating environments decreased the survival rates of resistant species, but increased survivorship of sensitive species. No one exposure duration under laboratory conditions could consistently be extrapolated to the suite of variable environments we examined. Probit analyses performed on the observed and simulated data indicated that LC-50s of different observed exposure durations were similar to each other and to the LC-50s of the simulated data assuming an exposure of 24 h. Based on these results, we recommend that toxicity studies incorporate temporal variability directly by using varying dose levels in laboratory tests.
17
MEKKI, Reem Yousif, Mohamed Hassan MUDAWI, Manahil Saidahmed MUSTAFA, Altaiyb Omer Ahmed MOHMMED, Ahmed Bakheet Abd ALLA, and Abdel Rahman AHMED. "Parametric Survival Models of Hemodialysis Patients in Relation with Patient-Related Factors." Medicina Moderna - Modern Medicine 27, no. 4 (December 20, 2020): 295–304. http://dx.doi.org/10.31689/rmm.2020.27.4.295.
Full textAbstract:
Background: Survival analysis refers to analyzing of statistical data for which the outcome variable of interest is time until an event occurs. This research aimed at comparing different models of parametric Proportional Hazards (PH) models (Weibull, exponential, Gompertz) in patients with hemodialysis to determine the best model for assessing the survival of patient. Study consists of 325 hemodialysis patients who referred to public hospitals in Khartoum state in the period from December 2005 to December 2015. Data was used to estimate the survival function with view to identify risk factors influencing among end-stage renal disease (ESRD) population. Based on the Cox-Snell Residuals and AIC, BIC, and Gompertz (PH) model is an efficient model than other when the values of (AIC=662.21), (BIC=703.83) and (R2=0.211) where maintained Study assessed that the variables dealing with univariate models were significant but had a significant effect on hemodialysis survival. The Gompertz model had the smallest AIC and BIC value; therefore; it was selected as the most appropriate model. In multivariable analysis, the BIC had the lowest value and the highest value in each analysis. The study assessed that diabetes mellitus and hypertension, regular, and hospital, had a. significant effect.
18
Dauda, Kazeem Adesina. "Optimal Tuning of Random Survival Forest Hyperparameter with an Application to Liver Disease." Malaysian Journal of Medical Sciences 29, no. 6 (December 22, 2022): 67–76. http://dx.doi.org/10.21315/mjms2022.29.6.7.
Full textAbstract:
Background: Random Forest (RF) is a technique that optimises predictive accuracy by fitting an ensemble of trees to stabilise model estimates. The RF techniques were adapted into survival analysis to model the survival of patients with liver disease in order to identify biomarkers that are highly influential in patient prognostics. Methods: The methodology of this study begins by applying the classical Cox proportional hazard (Cox-PH) model and three parametric survival models (exponential, Weibull and lognormal) to the published dataset. The study further applied the supervised learning methods of Tuning Random Survival Forest (TRSF) parameters and the conditional inference Forest (Cforest) to optimally predict patient survival probabilities. Results: The efficiency of these models was compared using the Akaike information criteria (AIC) and integrated Brier score (IBS). The results revealed that the Cox-PH model (AIC = 185.7233) outperforms the three classical models. We further analysed these data to observe the functional relationships that exist between the patient survival function and the covariates using TRSF. Conclusion: The IBS result of the TRFS demonstrated satisfactory performance over other methods. Ultimately, it was observed from the TRSF results that some of the covariates contributed positively and negatively to patient survival prognostics.
19
Mwau, Cynthia Mwende, Patrick Guge Weke, Bundi Davis Ntwiga, and Joseph Makoteku Ottieno. "Phase Type Zero Truncated Poisson Lindley Distributions and their application in modeling Secondary Cancer Cases." Afrika Statistika 9, no. 1 (January 1, 2022): 3145–64. http://dx.doi.org/10.16929/as/20212.3145.199.
Full textAbstract:
Insurance of chronic illness is slowly gaining ground in Kenya which has lead to insurance firms introducing insurance products of chronic illness among them being cancer insurance policies. However, unlike other chronic illnesses, cancer can move from the organ of origin to another which will consequently lead to increased cost of treatment. This can not be modeled using ordinary distributions hence it has become an area of interest for many researchers. Zero-truncated phase type distributions are used to solve this drawback of ordinary distributions as it can in-cooperate these transitions while modeling claim count data. They further improve modeling of claim count data as they only consider positive values of claim count excluding zeros. This is the nature of real claim count data as zero claim frequency can not attract any claim severity amount. In this paper aggregate claim losses of secondary cancers in Kenya are estimated using Zero-truncated Poisson Lindley distributions. Zero-truncated one parameter as well as Zero-truncated two parameter Poisson Lindley distributions are derived. Their compound probability generating functions are also constructed. The transitions states of secondary cancer states are estimated using continuous Chapman Kolmogorov equation and used as the matrix parameters for the claim count distributions. Pareto, Generalized Pareto, Weibull, OPPL and TPPL distributions are the distributions considered in this research in modeling claim numbers. This study concludes that aggregate losses of secondary cancer cases using Kenyan data are best modeled by PH-ZTOPPL Generalized Pareto model for PH-ZTOPPL distribution models while for PH-ZTTPPL distribution models the best model was PH-ZTTPPL-Generalized Pareto model. The two best models were compared and PH-ZTTPPL-Generalized Pareto model was proven to be the best model. Comparing this model with PH-TPPL Generalized Pareto model from earlier research PH-TPPL Generalized Pareto model proved to be a better model implying that zero claim count data should be considered in estimation of aggregate losses
20
Diao, Enjie, Kun Ma, Hui Zhang, Peng Xie, Shiquan Qian, Huwei Song, Ruifeng Mao, and Liming Zhang. "Thermal Stability and Degradation Kinetics of Patulin in Highly Acidic Conditions: Impact of Cysteine." Toxins 13, no. 9 (September 16, 2021): 662. http://dx.doi.org/10.3390/toxins13090662.
Full textAbstract:
The thermal stability and degradation kinetics of patulin (PAT, 10 μmol/L) in pH 3.5 of phosphoric-citric acid buffer solutions in the absence and presence of cysteine (CYS, 30 μmol/L) were investigated at temperatures ranging from 90 to 150 °C. The zero-, first-, and second-order models and the Weibull model were used to fit the degradation process of patulin. Both the first-order kinetic model and Weibull model better described the degradation of patulin in the presence of cysteine while it was complexed to simulate them in the absence of cysteine with various models at different temperatures based on the correlation coefficients (R2 > 0.90). At the same reaction time, cysteine and temperature significantly affected the degradation efficiency of patulin in highly acidic conditions (p < 0.01). The rate constants (kT) for patulin degradation with cysteine (0.0036–0.3200 μg/L·min) were far more than those of treatments without cysteine (0.0012–0.1614 μg/L·min), and the activation energy (Ea = 43.89 kJ/mol) was far less than that of treatment without cysteine (61.74 kJ/mol). Increasing temperature could obviously improve the degradation efficiency of patulin, regardless of the presence of cysteine. Thus, both cysteine and high temperature decreased the stability of patulin in highly acidic conditions and improved its degradation efficiency, which could be applied to guide the detoxification of patulin by cysteine in the juice processing industry.
21
Icen, Hayrunisa, Maria Rosaria Corbo, Milena Sinigaglia, Burcu Irem Omurtag Korkmaz, and Antonio Bevilacqua. "Using Microbial Responses Viewer and a Regression Approach to Assess the Effect of pH, Activity of Water and Temperature on the Survival of Campylobacter spp." Foods 11, no. 5 (February 22, 2022): 637. http://dx.doi.org/10.3390/foods11050637.
Full textAbstract:
This study aimed at developing a model for evaluating the survival of various Campylobacter jejuni strains under different conditions in culture media and poultry data from ComBase. Campylobacter data of culture media (116) and poultry (19) were collected from Microbial Responses Viewer, an additional tool of ComBase. The Weibull equation was selected as a suitable model for the analysis of survival data because of the nonlinearity of survival curves. Then, the fitting parameters (first reduction time and shape parameter) were analysed through a Kruskall–Wallis test and box-whisker plots, thus pointing out the existence of two classes of temperature (0–12 °C and 15–25 °C) and pH (4–6.5 and 7–7.5) acting on the viability of C. jejuni. Finally, a general regression model was used to build a comprehensive function; all factors were significant, but temperature was the most significant variable, followed by pH and water activity. In addition, desirability and prediction profiles highlighted a negative correlation of the first reduction time with temperature and a positive correlation with pH and water activity.
22
Peng, Di, Ni Zichun, and Hu Bin. "A New Analytic Method of Cold Standby System Reliability Model with Priority." MATEC Web of Conferences 175 (2018): 03060. http://dx.doi.org/10.1051/matecconf/201817503060.
Full textAbstract:
For different importance of components in equipment system, a cold standby system with two different components is studied when important components enjoy the priority in use and maintenance. Considering the application of exponential distribution, Weibull distribution and other typical distributions in resolving the problems subject to complicated calculation and strict constraints in the past reliability modelling, the highly applicable phase-type (PH) distribution is utilized to describe the life and maintenance time of system components in a unified manner. A system reliability model is built for wider applicability. With the matrix analysis method, expressions are obtained for a number of reliability indicators such as system reliability function, steady-state availability, mean up time and mean down time of system. In the end, examples are presented to verify the correctness and applicability of the model.
23
Coroller, L., I. Leguerinel, E. Mettler, N. Savy, and P. Mafart. "General Model, Based on Two Mixed Weibull Distributions of Bacterial Resistance, for Describing Various Shapes of Inactivation Curves." Applied and Environmental Microbiology 72, no. 10 (October 2006): 6493–502. http://dx.doi.org/10.1128/aem.00876-06.
Full textAbstract:
ABSTRACT Cells of Listeria monocytogenes or Salmonella enterica serovar Typhimurium taken from six characteristic stages of growth were subjected to an acidic stress (pH 3.3). As expected, the bacterial resistance increased from the end of the exponential phase to the late stationary phase. Moreover, the shapes of the survival curves gradually evolved as the physiological states of the cells changed. A new primary model, based on two mixed Weibull distributions of cell resistance, is proposed to describe the survival curves and the change in the pattern with the modifications of resistance of two assumed subpopulations. This model resulted from simplification of the first model proposed. These models were compared to the Whiting's model. The parameters of the proposed model were stable and showed consistent evolution according to the initial physiological state of the bacterial population. Compared to the Whiting's model, the proposed model allowed a better fit and more accurate estimation of the parameters. Finally, the parameters of the simplified model had biological significance, which facilitated their interpretation.
24
Shen, Zhichuan, Xinhua Zhou, Huina Qiu, Hua Xu, Huayao Chen, and Hongjun Zhou. "A Comparison Study of Antiultraviolet and Sustained Release Properties of Polydopamine/Avermectin Microcapsule and Microsphere." International Journal of Polymer Science 2018 (December 30, 2018): 1–13. http://dx.doi.org/10.1155/2018/7584281.
Full textAbstract:
By using dopamine (DA) as the monomer, the model drug avermectin (AVM) was loaded on polydopamine microspheres (AVM/PDAMS) and polydopamine microcapsules (AVM@PDAMC) by the method of impregnation and encapsulation, respectively. The materials’ structures were systematically characterized using Fourier transform infrared spectroscopy (FTIR), zeta potential analysis, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The comparison of antiultraviolet capability as well as release behaviors under different pH values of the materials were studied. The results showed that a spherical appearance was observed from both materials. The use of AVM/PDAMS and AVM@PDAMC made the decomposition temperature of AVM increase to 235°C and 245°C, respectively. After being exposed to ultraviolet light for 1400 min, the residual ratios of AVM of AVM/PDAMS and AVM@PDAMC were 42% and 54%, respectively. Both AVM/PDAMS and AVM@PDAMC showed acid sensitivity. AVM/PDAMS and AVM@PDAMC took about 13 h and 60 h to reach the release rate of 50% under pH 3. The release process of AVM/PDAMS could be explained by the Weibull model at pH 3, while the release behavior of AVM@PDAMC fitted the Baker–Lonsdale equation. At pH 7 and pH 9, both of the delivery materials followed the Korsmeyer–Peppas model and belonged to the Fick diffusion.
25
MUHAMMAD, ALIYU IDRIS, RUILING LV, XINYU LIAO, WEIJUN CHEN, DONGHONG LIU, XINGQIAN YE, SHIGUO CHEN, and TIAN DING. "Modeling the Inactivation of Bacillus cereus in Tiger Nut Milk Treated with Cold Atmospheric Pressure Plasma." Journal of Food Protection 82, no. 11 (October 9, 2019): 1828–36. http://dx.doi.org/10.4315/0362-028x.jfp-18-586.
Full textAbstract:
ABSTRACT The impact of cold atmospheric pressure plasma treatment on the inactivation kinetics of Bacillus cereus ATCC 14579 and the resulting quality changes was investigated in tiger nut (Cyperus esculentus L.) milk (TNM). The effect of input power (39, 43, and 46 W) and treatment time (0 to 270 s) was fitted using the Weibull model to represent the microbial kinetic inactivation in the treated TNM. Inactivation efficacy increased with an increase in treatment time and input power. A 5.28-log reduction was achieved at 39 to 46 W without significant changes in titratable acidity, whereas no reduction in titratable acidity was observed in the pasteurized sample. The inactivation kinetics was adequately described by the Weibull model. Higher input power of 43 and 46 W and 120 s of treatment resulted in marked decreases in pH, flavonoid concentration, and antioxidant activity compared with those parameters in pasteurized TNM. Increases in total color difference and phenolic concentrations also were observed. The results indicate that these changes were caused by the immanent plasma reactive species. This study provides valuable inactivation kinetics information for food safety assessment studies of B. cereus vegetative cells in TNM.
26
SEO, KYEONGJIN, JUNG EUN LEE, MI YOUNG LIM, and GWANGPYO KO. "Effect of Temperature, pH, and NaCl on the Inactivation Kinetics of Murine Norovirus." Journal of Food Protection 75, no. 3 (March 1, 2012): 533–40. http://dx.doi.org/10.4315/0362-028x.jfp-11-199.
Full textAbstract:
We investigated the resistance of murine norovirus (MNV) and coliphage MS2, a culturable human norovirus surrogate, to temperature, salt, and pH. Virus inactivation was measured by plaque, real-time TaqMan reverse transcription (RT) PCR, and long-template RT-PCR assays. Both MNV and MS2 were rapidly inactivated at temperatures above 60°C. Similarly, MNV tolerated low salt concentrations (0.3% NaCl) to a greater degree than high salt concentrations (3.3 to 6.3% NaCl). MNV was relatively resistant to strong acidic conditions (pH 2) and was more tolerant of slightly acidic (pH 4) or neutral (pH 7) conditions. In contrast, MS2 was resistant to high salinity. Overall, temperature had a greater effect on infectivity than salt or low pH. Additionally, temperature and low pH had a synergistic effect on MNV infectivity. Both real-time and long-template RT-PCR assays significantly underestimated the inactivation by temperature, salt, and pH. The inactivation kinetics of both MNV and MS2 under various environmental conditions gave a good fit by the Weibull model (R2 > 0.9). This study suggests both the capacity of infectious human norovirus to persist in the face of various environmental conditions and its sensitivity to high temperatures, which may provide a mechanism of protection against this virus.
27
Chen, Fujia, Yilin Xu, Nana Ding, Hongyan Li, Tongbiao Li, Fengyun Liu, Mengxue Liang, et al. "Extraction of Radix trichosanthis Polysaccharides for Potential Antihyperlipidemic Application." BioMed Research International 2022 (April 11, 2022): 1–10. http://dx.doi.org/10.1155/2022/3811036.
Full textAbstract:
This study focused on the optimization of ultrasound-assisted compound enzyme extraction for polysaccharides (RTPs) from Radix trichosanthis by orthogonal experiment and response surface methodology, and then its extraction kinetics model and antihyperlipidemic activities were studied. The optimum extraction process was as follows: cellulase—1.0%, papain—1.0%, pectase—0.5%, pH—5, extraction temperature—50°C, and liquid-to-solid ratio—30 mL/g; prediction value of RTPs was 7.54%; the experimental yield of RTPs was 7.22%, while 50 minutes was optimized in Weibull kinetics model. Then high-dose groups of RTP extract could reduce the TC, TG, and LDL-C levels and increase the level of HDL-C in high-fat mice, with the ability to lower the MDA content and enhance SOD level.
28
Balleño, J. A., A. P. Mendizábal-Ruiz, H. Saade, R. Díaz de León-Gómez, E. Mendizábal, N. Rios-Donato, and R. G. López. "Ibuprofen Release from Poly(ethyl cyanoacrylate) Nanoparticles Prepared by Semicontinuous Heterophase Polymerization." International Journal of Polymer Science 2018 (2018): 1–8. http://dx.doi.org/10.1155/2018/4527203.
Full textAbstract:
Ibuprofen-loaded poly(ethyl cyanoacrylate) nanoparticles were prepared by semicontinuous heterophase polymerization of ethyl cyanoacrylate in the presence of ibuprofen; different surfactant concentration, pH, and temperature were used. Particle size was measured by quasi-light scattering and transmission electron microscopy, while the amount of drug released was determined by UV spectroscopy. Nanoparticles with diameters between 10 and 58 nm, loaded with ibuprofen, were obtained. The smallest particles and the higher drug loading were obtained at the highest pH tested. The analysis of the release data showed that the drug release profiles correspond to the Weibull model. Moreover, it was found that most of the ibuprofen is released within the first 80–120 min; initially the release rate is slow, but then it increases to finally decrease. This behavior contrasts with the reported burst of drug concentration in the plasma after oral administration of IB.
29
Chen, Long, Hongjun Zhou, Li Hao, Huayao Chen, and Xinhua Zhou. "Soy protein isolate-carboxymethyl cellulose conjugates with pH sensitivity for sustained avermectin release." Royal Society Open Science 6, no. 7 (July 2019): 190685. http://dx.doi.org/10.1098/rsos.190685.
Full textAbstract:
Carboxymethyl cellulose (CMC) was grafted onto the surface of soy protein isolate (SPI) to obtain soy protein isolate-carboxymethyl cellulose conjugate (SPC). Avermectin (AVM) was hydrophobically encapsulated as a model drug to obtain SPC@AVM. The reaction between SPI and CMC was confirmed by infrared spectroscopy, thermal analysis and SDS-PAGE electrophoresis. The results of scanning electron microscopy showed that the average particle size of the drug-loaded microspheres was 129 nm and the shape of microspheres changed from block to spherical after the addition of AVM. After encapsulation of AVM, the absolute value of zeta potential was greater than 15 mV, which indicated better stability. Compared to AVM solution, SPC@AVM showed more wettability on the leaf surface and the contact angle on the leaves decreased from 71.64° to 57.33°. The maximum liquid holding capacity increased by 41.41%, from 8.85 to 12.52 mg cm −2 , which effectively reduced leaf loss. SPC@AVM also prevented UV photolysis, wherein the half-life was extended from 18 to 68 min when exposed to UV light. Moreover, toxicity tests showed that the encapsulation of AVM was beneficial to retain the insecticidal effect of AVM in the presence of ultraviolet light. The release rate of AVM showed pH responsiveness and the release rate under neutral conditions was faster than acidic and alkaline conditions. Moreover, the process conformed to the Weibull model.
30
Mitrevska, Ivana, Katerina Brezovska, Aneta Dimitrovska, Suzan Memed-Sejfulah, and Sonja Ugarkovic. "Optimization and statistical evaluation of discriminative dissolution method for bisoprolol immediate-release film coated tablets." Macedonian Pharmaceutical Bulletin 66, no. 1 (2020): 43–53. http://dx.doi.org/10.33320/maced.pharm.bull.2020.66.01.005.
Full textAbstract:
This study presents optimization of a statistically based approach for setting up the dissolution test conditions for bisoprolol film-coated tablets using multivariate release models as predictive in vivo assessment tools for formulation behaviour. Additionally, the dissolution profiles of three different strengths of bisoprolol film-coated tablets were evaluated. According to the biopharmaceutics classification system, the tested medicinal product belongs to BCS Class I (high solubility, high permeability). Three dissolution media, including the dissolution medium of choice (pH 1.2) according to the USP monograph for bisoprolol tablets and two apparatus, paddle and basket were applied. The optimal conditions for performing the dissolution test were following: 900 mL of pH 1.2 as dissolution medium, apparatus 2 (paddle) with 75 r/min stirring speed. The quantity of the released active substance was determined using HPLC method. For a reliable statistical analysis, multivariate methods such as model-dependent approach coupled to multivariate statistics (Weibull), multivariate model-independent approach based on generalized statistical distance (Mahalanobis distance) have been applied for evaluation of dissolution profiles. All applied statistical approaches unequivocally support the underlying similarity of the pairs in different media between different strengths. Moreover, the optimized dissolution method has a discriminatory power to reflect the characteristics of the medicinal product in order to distinguish any changes related to quantitative composition of the formulation. Keywords: bisoprolol film-coated tablet, dissolution profiles, model-independent multivariate statistical distance, model-dependent multivariate statistical distance
31
Liu, Weitao, Jiyuan Zhao, Ruiai Nie, Yifan Zeng, Baichao Xu, and Xi Sun. "A Full Coupled Thermal–Hydraulic–Chemical Model for Heterogeneity Rock Damage and Its Application in Predicting Water Inrush." Applied Sciences 9, no. 11 (May 29, 2019): 2195. http://dx.doi.org/10.3390/app9112195.
Full textAbstract:
A coupled thermal–hydraulic–chemical (THC) model was carried out in this paper to study the influence of rock heterogeneity and the coupling effect of temperature, groundwater, and hydrochemistry on rock damage. Firstly, the hydrochemical and hydraulic erosion equations were established. The equations of the coupled THC model were established by combining the hydrochemical and hydraulic erosion equations, the flow equations, and the heat transfer equations. Weibull distribution was adopted to govern the heterogeneity of initial rock porosity distribution. Secondly, the influence of the hydrochemistry, the temperature and the initial porosity heterogeneity on porosity and fluid velocity change was studied. Then the rock damage rule changed with time at different pH values and temperature was studied. Finally, an actual deep coal mine model was established to apply the THC model to predict water inrush. Results indicate that: (1) The average porosity and average fluid velocity approximately show linear growth and exponential growth with time, respectively, and their growth rates increase with decreasing pH value and increasing temperature in a certain acidity and temperature range. (2) The increase of initial porosity heterogeneity has little influence on porosity change, but it can increase the fluid velocity growth rate. The porosity heterogeneity and fluid velocity heterogeneity approximately show exponential growth with increasing time, and the rock heterogeneity growth contributes to form cracks. The increase of temperature and decrease of pH value have little influence on the porosity heterogeneity, but they can increase the growth rate of the fluid velocity heterogeneity. (3) The rock damage shows linear growth with time, and its growth rate increases with decreasing pH value and increasing temperature in a certain acidity range and temperature range. (4) The increase of rock heterogeneity can increase the possibility of water inrush.
32
Abdelsattar, Mahmoud, Yimin Zhuang, Kai Cui, Yanliang Bi, and Naifeng Zhang. "Predicting the Digestive Tract Development and Growth Performance of Goat Kids Using Sigmoidal Models." Animals 11, no. 3 (March 10, 2021): 757. http://dx.doi.org/10.3390/ani11030757.
Full textAbstract:
The transition from monogastric to rumination stage is crucial in ruminants’ growth to avoid stressors—weaning and neonatal mortalities. Poor growth of the digestive tract could adversely affect the performance of the animal. Modeling informative growth curves is of great importance for a better understanding of the effective development pattern, in order to optimize feeding management system, and to achieve more production efficiency. However, little is known about the digestive tract growth curves. For this reason, one big goat farm of Laiwu black breed was chosen as a basis of this study. Forty-eight kids belonging to eight-time points (1, 7, 14, 28, 42, 56, 70, and 84 d; 6 kids for each) were selected and slaughtered. The body weight, body size indices, rumen pH, and stomach parts were determined and fitted to the polynomial and sigmoidal models. In terms of goodness of fit criteria, the Gompertz model was the best model for body weight, body oblique length, tube, and rumen weight. Moreover, the Logistic model was the best model for carcass weight, body height, and chest circumference. In addition, the Quadratic model showed the best fit for dressing percentage, omasum weight, abomasum weight, and rumen volume. Moreover, the cubic model best fitted the ruminal pH and reticulum percentage. The Weibull model was the best model for the reticulum weight and omasum percentage, while the MMF model was the best model describing the growth of chest depth, rumen percentage, and abomasum percentage. The model parameters, R squared, inflection points, area under curve varied among the different dependent variables. The Pearson correlation showed that the digestive tract development was more correlated with age than body weight, but the other variables were more correlated with body weight than age. The study demonstrated the use of empirical sigmoidal and polynomial models to predict growth rates of the digestive tract at relevant age efficiently.
33
Partheniadis, Gkogkou, Kantiranis, and Nikolakakis. "Modulation of the Release of a Non-Interacting Low Solubility Drug from Chitosan Pellets Using Different Pellet Size, Composition and Numerical Optimization." Pharmaceutics 11, no. 4 (April 10, 2019): 175. http://dx.doi.org/10.3390/pharmaceutics11040175.
Full textAbstract:
Two size classes of piroxicam (PXC) pellets (mini (380–550 μm) and conventional (700–1200 μm)) were prepared using extrusion/spheronization and medium viscosity chitosan (CHS). Mixture experimental design and numerical optimization were applied to distinguish formulations producing high sphericity pellets with fast or extended release. High CHS content required greater wetting liquid volume for pellet formation and the diameter decreased linearly with volume. Sphericity increased with CHS for low-to-medium drug content. Application of PXRD showed that the drug was a mixture of form II and I. Crystallinity decreased due to processing and was significant at 5% drug content. Raman spectroscopy showed no interactions. At pH 1.2, the dissolved CHS increased ‘apparent’ drug solubility up to 0.24 mg/mL while, at pH 5.6, the suspended CHS increased ‘apparent’ solubility to 0.16 mg/mL. Release at pH 1.2 was fast for formulations with intermediate CHS and drug levels. At pH 5.6, conventional pellets showed incomplete release while mini pellets with a CHS/drug ratio ≥2 and up to 21.25% drug, showed an extended release that was completed within 8 h. Numerical optimization provided optimal formulations for fast release at pH 1.2 with drug levels up to 40% as well as for extended release formulations with drug levels of 5% and 10%. The Weibull model described the release kinetics indicating complex or combined release (parameter ‘b’ > 0.75) for release at pH 1.2, and normal diffusion for the mini pellets at pH 5.6 (‘b’ from 0.63 to 0.73). The above results were attributed mainly to the different pellet sizes and the extensive dissolution/erosion of the gel matrix was observed at pH 1.2 but not at pH 5.6.
34
Maulana, Mochammad Yusuf, and I. Made Arcana. "Determinan Risiko Kematian Pasien Covid-19." Seminar Nasional Official Statistics 2022, no. 1 (November 1, 2022): 977–84. http://dx.doi.org/10.34123/semnasoffstat.v2022i1.1301.
Full textAbstract:
Pandemi Covid-19 di Indonesia pada pertengahan Tahun 2021 menunjukkan adanya peningkatan jumlah penduduk yang terpapar virus corona dan jumlah kematian pasien Covid-19. Kondisi yang relatif sama terjadi juga di Kota Tegal, dimana risiko kematian pada pasien Covid-19 cukup tinggi. Penelitian ini bertujuan untuk mengidentifikasi variabel yang secara signifikan memengaruhi risiko kematian pasien Covid-19, berdasarkan data rekam medis pasien pada periode Januari sampai Agustus 2021 di RSUD Kardinah yang merupakan RS pendidikan dan RS rujukan Covid-19 lini pertama di Kota Tegal. Sejumlah 477 pasien rawat inap Covid-19 menjadi subjek pengamatan dalam penelitian ini. Metode analisis yang diterapkan adalah analisis survival dengan mengimplementasikan model Weibull Proportional Hazard (PH) yang model terbaiknya ditetapkan berdasarkan nilai AIC terkecil. Hasil penelitian menunjukkan bahwa tingkat risiko kematian tertinggi terjadi pada pasien berjenis kelamin perempuan yang sesak nafas, yaitu sebesar 2,9 kali risiko kematian yang dialami pasien perempuan yang tidak sesak nafas.
35
Marinheiro, Diogo, Bárbara Ferreira, Párástu Oskoei, Helena Oliveira, and Ana Daniel-da-Silva. "Encapsulation and Enhanced Release of Resveratrol from Mesoporous Silica Nanoparticles for Melanoma Therapy." Materials 14, no. 6 (March 12, 2021): 1382. http://dx.doi.org/10.3390/ma14061382.
Full textAbstract:
Chemotherapy has limited success in the treatment of malignant melanoma due to fast development of drug resistance and the low bioavailability of chemotherapeutic drugs. Resveratrol (RES) is a natural polyphenol with recognized preventive and therapeutic anti-cancer properties. However, poor RES solubility hampers its bioactivity, thus creating a demand for suitable drug delivery systems to improve it. This work aimed to assess the potential of RES-loaded mesoporous silica nanoparticles (MSNs) for human melanoma treatment. RES was efficiently loaded (efficiency > 93%) onto spheroidal (size~60 nm) MSNs. The encapsulation promoted the amorphization of RES and enhanced the release in vitro compared to non-encapsulated RES. The RES release was pH-dependent and markedly faster at pH 5.2 (acid environment in some tumorous tissues) than at pH 7.4 in both encapsulated and bulk forms. The RES release from loaded MSNs was gradual with time, without a burst effect, and well-described by the Weibull model. In vitro cytotoxicity studies on human A375 and MNT-1 melanoma cellular cultures showed a decrease in the cell viability with increasing concentration of RES-loaded MSNs, indicating the potent action of the released RES in both cell lines. The amelanotic cell line A375 was more sensitive to RES concentration than the melanotic MNT-1 cells.
36
Wardhani, Dyah H., Fatiha N. Etnanta, Hana N. Ulya, and Nita Aryanti. "Iron Encapsulation by Deacetylated Glucomannan as an Excipient Using the Gelation Method: Characteristics and Controlled Release." Food Technology and Biotechnology 60, no. 1 (November 16, 2021): 41–51. http://dx.doi.org/10.17113/ftb.60.01.22.7130.
Full textAbstract:
Research background. Deacetylation and the use of CaCl2 as a gelation agent improve the performance of glucomannan as iron encapsulant. This study was conducted to investigate the effects of deacetylation degree and pH of gelation on the characteristics of encapsulated iron using gelation in CaCl2 solution. Experimental approach. Glucomannan was deacetylated at various NaOH concentrations and was subsequently utilized as an iron excipient using the pipette-dropped gelation method in CaCl2 solution to directly investigate the process of encapsulation by gelation. The pH of the gelation solution was also changed. The beads were subsequently vacuum-dried. Results and conclusions. Deacetylation led to lower endothermic peak of the glucomannan than that of the native one. The deacetylation degree and pH of gelation did not significantly affect the diameter of the beads but influenced their appearance and physical characteristics. The backbone of glucomannan was not changed by either the deacetylation degree or the pH of the gelation. The highest encapsulation efficiency (73.27 %) was observed in the encapsulated iron using the glucomannan matrix of the highest deacetylation degree (82.56 %) and gelated in the solution at pH=10. The highest deacetylation degree of glucomannan caused the highest swelling of the beads, which led to the release of a higher amount of iron. Glucomannan deacetylation improves the iron encapsulation and enables higher iron release at pH=6.8 than at pH=1.2. The Weibull model was the best-fitting model to represent the profile of iron release from the deacetylated glucomannan matrix using the gelation method (R2>0.93) at pH=6.8 and pH=1.2. Novelty and scientific contribution. This result supports the application of deacetylated glucomannan using NaOH as a pH-sensitive matrix for iron encapsulation and CaCl2 solution as gelation agent. A higher deacetylation degree leads to the release of a higher amount of iron from the matrix. The encapsulation does not only protect the iron but also delivers it to the absorption site and controls its release, which is useful in supplement formulation or food fortification. The results show that the deacetylated glucomannan as the matrix holds more iron in encapsulation process.
37
Muse, Abdisalam Hassan, Christophe Chesneau, Oscar Ngesa, and Samuel Mwalili. "Flexible Parametric Accelerated Hazard Model: Simulation and Application to Censored Lifetime Data with Crossing Survival Curves." Mathematical and Computational Applications 27, no. 6 (November 30, 2022): 104. http://dx.doi.org/10.3390/mca27060104.
Full textAbstract:
This study aims to propose a flexible, fully parametric hazard-based regression model for censored time-to-event data with crossing survival curves. We call it the accelerated hazard (AH) model. The AH model can be written with or without a baseline distribution for lifetimes. The former assumption results in parametric regression models, whereas the latter results in semi-parametric regression models, which are by far the most commonly used in time-to-event analysis. However, under certain conditions, a parametric hazard-based regression model may produce more efficient estimates than a semi-parametric model. The parametric AH model, on the other hand, is inappropriate when the baseline distribution is exponential because it is constant over time; similarly, when the baseline distribution is the Weibull distribution, the AH model coincides with the accelerated failure time (AFT) and proportional hazard (PH) models. The use of a versatile parametric baseline distribution (generalized log-logistic distribution) for modeling the baseline hazard rate function is investigated. For the parameters of the proposed AH model, the classical (via maximum likelihood estimation) and Bayesian approaches using noninformative priors are discussed. A comprehensive simulation study was conducted to assess the performance of the proposed model’s estimators. A real-life right-censored gastric cancer dataset with crossover survival curves is used to demonstrate the tractability and utility of the proposed fully parametric AH model. The study concluded that the parametric AH model is effective and could be useful for assessing a variety of survival data types with crossover survival curves.
38
Albayati, Talib M., and Ali M. AlKafajy. "Mesoporous Silica MCM-41 as a Carriers Material for Nystatine Drug in Delivery System." Al-Khwarizmi Engineering Journal 15, no. 2 (May 15, 2019): 34–43. http://dx.doi.org/10.22153/kej.2019.11.003.
Full textAbstract:
In the present study, MCM-41 was synthesis as a carrier for poorly drugs soluble in water, by the sol-gel technique. Textural and chemical characterizations of MCM-41 were carried out by X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscope (SEM), and thermal gravimetric analysis (TGA). The experimental results were analyzed mesoporous carriers MCM-41. With maximum drug loading efficiency in MCM-41 determined to be 90.74%. The NYS released was prudently studied in simulated body fluid (SBF) pH 7.4 and the results proved that the release of NYS from MCM-41 was (87.79%) after 18 hr. The data of NYS released was found to be submitted a Weibull model with a correlation coefficient of (0.995). The Historical data experimental design facilitated the formulation and optimization of sustained discover the optimal formulation to loading drug, combine process variables, mixture components and categorical factors in one design.
39
Gutierrez, Alan, and Keith R. Schneider. "Survival and inactivation kinetics of Salmonella enterica serovar Typhimurium in irradiated and natural poultry litter microcosms." PLOS ONE 17, no. 4 (April 19, 2022): e0267178. http://dx.doi.org/10.1371/journal.pone.0267178.
Full textAbstract:
The use of poultry litter as a biological soil amendment presents a risk for the preharvest contamination of fresh produce by Salmonella. In order to properly assess this risk, it is important to understand the factors influencing the persistence of Salmonella in poultry litter. This research was performed to investigate the influence of indigenous microflora on the survival of Salmonella Typhimurium in poultry litter. Microcosms of irradiated (sterilized) and natural poultry litter were inoculated with S. Typhimurium, adjusted to pH 8.0, 0.92 water activity (aw), and stored at 30°C for 6 days. S. Typhimurium populations (log CFU g-1) declined in both litter treatments and there were no significant differences (P > 0.05) in recovery between litter treatments on any sampling days (0 to 6). The pH of the natural litter significantly increased (P < 0.05) from 8.42 on day 0 to 9.00 on day 6. By day 6, S. Typhimurium populations in both litter treatments fell below the limit of detection (1 log CFU g-1). The inactivation kinetics of S. Typhimurium in both litter treatments were described by the Weibull model. Under the experimental conditions (pH 8.0, 0.92 aw, 30°C), the presence or absence of poultry litter microflora did not significantly influence the survival of S. Typhimurium. This study demonstrates that the mere presence of poultry litter microflora will not inhibit Salmonella survival. Instead, inhibitory interactions between various microorganisms in litter and Salmonella are likely dependent on more favorable environmental conditions (e.g., aw, pH) for growth and competition.
40
Hooper, Ellen, Xingdi Hu, Peggy L. Lin, and Daniel J. DeAngelo. "QoL of pediatric-inspired compared to hyper-CVAD regimens for newly diagnosed AYA patients with Ph-ALL: A modeling analysis." Journal of Clinical Oncology 35, no. 15_suppl (May 20, 2017): e22002-e22002. http://dx.doi.org/10.1200/jco.2017.35.15_suppl.e22002.
Full textAbstract:
e22002 Background: The treatment of acute lymphoblastic leukemia (ALL) requires 2+ years of intensive multi-agent chemotherapy, with significant impact on quality of life (QoL). While treatment protocols exist for adolescent / young adult (AYA) patients, there is limited evidence on the QoL impact for patients treated with pediatric-inspired protocols, which include asparaginase, versus regimens such as Hyper-CVAD. Objective: To compare the QoL impact of pediatric-inspired vs Hyper-CVAD regimens in the 1st-line treatment of AYA patients with Ph- ALL using disease simulation. Methods: A 6-state Markov model was developed to simulate total life-years and quality-adjusted life-years (QALYs) for AYA ALL patients receiving 1st line pediatric-inspired or Hyper-CVAD regimens. Modeled health states were: no first complete remission (no treatment/non-response to 1st line), first complete remission, first relapse, second complete remission, second relapse, and death. Model inputs for CR, EFS, OS, AEs, and health utility were obtained from literature. Weibull function was fitted to extrapolate survival and QALY over time. Results: Compared with Hyper-CVAD, the pediatric-inspired protocol resulted in increased life-years and QALYs at years 5, 10 and through a lifetime horizon. Benefits were mainly driven by more favorable progression-free survival and OS of patients in pediatric-inspired protocols compared to hyper-CVAD. Conclusions: This disease simulation model suggests that pediatric-inspired protocols for newly diagnosed AYA patients with Ph- ALL may increase QoL, as measured by QALYs, compared to Hyper-CVAD. Future long-term follow-up studies are needed to confirm these findings. [Table: see text]
41
Narissara Kulpreechanan and Feuangthit Niyamissara Sorasitthiyanukarn. "Evaluation of in vitro release kinetics of Capsaicin-loaded chitosan nanoparticles using DDSolver." International Journal of Research in Pharmaceutical Sciences 11, no. 3 (July 31, 2020): 4555–59. http://dx.doi.org/10.26452/ijrps.v11i3.2685.
Full textAbstract:
The present aim is to evaluate the release profile and its release kinetics of encapsulated capsaicin from chitosan nanoparticles using the software DDSolver. The release study was performed by using a dialysis technique in PBS solutions with different pHs (1.2, 6.8 and 7.4) to mimics the different gastrointestinal tract and circulatory system pH ranges as a releasing medium. The nanoparticles were prepared using o/w emulsification and ionotropic gelation technique under optimal condition obtained from response surface methodology (RSM) design as described in our previous study. These nanoparticles were around 180 nm in average hydrodynamic size and encapsulation efficiency percentage around 70%, respectively. In vitro drug release study suggested that the chitosan nanoparticles can potentially use to controlled and sustained release of capsaicin over at least 96. The kinetic release analysis results by DDSolver software indicated that Weibull model was suggested to be the best dynamic models with highest R2adjusted and model selection criteria (MSC) and lowest Akaike information criterion (AIC), respectively, for capsaicin loaded chitosan nanoparticles. The release mechanism of capsaicin from nanoparticles was found to be Fickian diffusion. The results suggest that the chitosan nanoparticles can be applied for the controlled and sustained release of capsaicin in the gastrointestinal tract and circulatory system.
42
Al Nuss, Raghad, and Hind El Zein. "Cefdinir Inclusion in Mesoporous Silica as Effective Dissolution Enhancer with Improved Physical Stability." Journal of Pharmacy and Nutrition Sciences 11 (October 21, 2021): 73–86. http://dx.doi.org/10.29169/1927-5951.2021.11.10.
Full textAbstract:
Objective: The objective of this research was to enhance the physical stability and the dissolution rate of cefdinir, a BCS class IV drug, characterized by low and variable bioavailability due to both its low solubility and low permeability. Methods: Cefdinir was loaded into the mesoporous silica (SBA-15), by using the solvent immersion method starting from different organic solvents. And then formula (F3), which exhibited the highest loading percentage, was selected to study its drug release in media with different pH (1.2, 4.5, and 6.8), and has been fully characterized by using: Fourier Transform Infrared Spectroscopy (FT-IR) Spectroscopy, Differential Scanning Calorimetry, Powder X-ray Diffraction, and has been subjected to accelerated stability tests using different temperatures and relative humidity. Drug release kinetics were studied by using the following models: Probit, Gompertz, Weibull, and Logistic. Results: The results showed a remarkable dissolution improvement of cefdinir from the loaded silica in comparison to the crystalline drug at the different studied media. Drug release behaviors were well simulated by the Weibull model for F3 in all studied media and for pure Cefdinir in phosphate buffer only, and by the Gompertz function for pure Cefdinir in HCl buffer and Acetate buffer. FTIR results showed hydrogen bonds formed between the drug and silica, DSC and PXRD results revealed the transformation of cefdinir into an amorphous form upon adsorption. Stability studies under different conditions revealed the ability of mesoporous silica to maintain the amorphous state of the drug, which has been formed upon adsorption, and to prevent re-organization in the crystal nucleus of the drug molecules. Conclusion: Thus, loading cefdinir onto mesoporous silica can be used as a promising method to enhance drug dissolution, and maintain the physical stability of its amorphous form.
43
Núñez-Núñez, Cynthia M., Guillermo I. Osorio-Revilla, Ignacio Villanueva-Fierro, Christian Antileo, and José B. Proal-Nájera. "Solar Fecal Coliform Disinfection in a Wastewater Treatment Plant by Oxidation Processes: Kinetic Analysis as a Function of Solar Radiation." Water 12, no. 3 (February 27, 2020): 639. http://dx.doi.org/10.3390/w12030639.
Full textAbstract:
The final step in the treatment of municipal wastewater is disinfection, which is required to inactivate microorganisms that have survived after treatment. Chlorine and chloramines are widely used disinfectants in wastewater treatment plants (WWTP); however, the use of chlorine as a disinfectant presents several problems. In the present research, solar disinfection and photocatalytic disinfection processes have been applied to inactivate the fecal coliform microorganisms that are present in municipal wastewater treated by activated sludge in a WWTP. A 2 × 3 × 2 factorial design was applied. The first factor was the process: solar disinfection or photocatalysis; the second was initial pH: 5, 7.5 and 9; the third was the presence or absence of a H2O2 dose of 1 mMol added at the beginning of the process. The data from experimentation were compared to predictions from different inactivation kinetic models (linear, linear + shoulder, linear + tail, Weibull and biphasic). The results show that H2O2 addition plays an important role in the process and that disinfection does not always follow a linear reaction model. When related to radiation, it becomes clear that the accumulated radiation dose, rather than the time, should be considered the most important factor in the solar disinfection process.
44
Fernández, A., J. Collado, L. M. Cunha, M. J. Ocio, and A. Martı́nez. "Empirical model building based on Weibull distribution to describe the joint effect of pH and temperature on the thermal resistance of Bacillus cereus in vegetable substrate." International Journal of Food Microbiology 77, no. 1-2 (July 2002): 147–53. http://dx.doi.org/10.1016/s0168-1605(02)00046-6.
Full text
45
BLACK, D. GLENN, FEDERICO HARTE, and P. MICHAEL DAVIDSON. "Escherichia coli Thermal Inactivation Relative to Physiological State." Journal of Food Protection 72, no. 2 (February 1, 2009): 399–402. http://dx.doi.org/10.4315/0362-028x-72.2.399.
Full textAbstract:
Studies have explored the use of various nonlinear regression techniques to better describe shoulder and/or tailing effects in survivor curves. Researchers have compiled and developed a number of diverse models for describing microbial inactivation and presented goodness of fit analysis to compare them. However, varying physiological states of microorganisms could affect the measured response in a particular population and add uncertainty to results from predictive models. The objective of this study was to determine if the shape and magnitude of the survivor curve are possibly the result of the physiological state, relative to growth conditions, of microbial cells at the time of heat exposure. Inactivation tests were performed using Escherichia coli strain K-12 in triplicate for three growth conditions: statically grown cells, chemostat-grown cells, and chemostat-grown cells with buffered (pH 6.5) feed media. Chemostat cells were significantly less heat resistant than the static or buffered chemostat cells at 58°C. Regression analysis was performed using the GInaFiT freeware tool for Microsoft Excel. A nonlinear Weibull model, capable of fitting tailing effects, was effective for describing both the static and buffered chemostat cells. The log-linear response best described inactivation of the nonbuffered chemostat cells. Results showed differences in the inactivation response of microbial cells depending on their physiological state. The use of any model should take into consideration the proper use of regression tools for accuracy and include a comprehensive understanding of the growth and inactivation conditions used to generate thermal inactivation data.
46
Kim, Ji Yoon, Eun Bi Jeon, Man-Seok Choi, Eun Ha Choi, Jun Sup Lim, Jinsung Choi, and Shin Young Park. "The Efficiency of Atmospheric Dielectric Barrier Discharge Plasma against Escherichia coli and Bacillus cereus on Dried Laver (Porphyra tenera)." Foods 9, no. 8 (July 28, 2020): 1013. http://dx.doi.org/10.3390/foods9081013.
Full textAbstract:
This study investigated the effects of atmospheric dielectric barrier discharge (DBD) plasma (1.1 kV, 43 kHz, 5–30 min, N2: 1.5 L/m) on the reduction of Escherichia coli and Bacillus cereus on dried laver. The reductions of E. coli and B. cereus by 5, 10, 20, and 30 min of DBD plasma were 0.56 and 0.24, 0.61 and 0.66, 0.76 and 1.24, and 1.02 and 1.38 log CFU/g, respectively. The D-value of E. coli and B. cereus was predicted as 29.80 and 20.53 min, respectively, using the Weibull model for E. coli (R2 = 0.95) and first-order kinetics for B. cereus (R2 = 0.94). After DBD plasma 5–30 min treatment, there was no change in pH (6.20–6.21) and this value was higher than the untreated dried laver (6.08). All sensory scores in DBD plasma-treated laver were determined as >6 points. The 30 min of DBD plasma is regarded as a novel intervention for the control of potential hazardous bacteria in dried laver.
47
Temova Rakuša, Žane, Mitja Pišlar, Albin Kristl, and Robert Roškar. "Comprehensive Stability Study of Vitamin D3 in Aqueous Solutions and Liquid Commercial Products." Pharmaceutics 13, no. 5 (April 25, 2021): 617. http://dx.doi.org/10.3390/pharmaceutics13050617.
Full textAbstract:
Vitamin D3 has numerous beneficial effects, such as musculoskeletal, immunomodulatory, and neuroprotective. However, its instability is the main obstacle to formulating quality products. Despite increased attention and growing use, data on vitamin D3 stability is scarce because data from individual studies is inconclusive and mostly qualitative. Therefore, we have systematically investigated the influence of various factors (temperature, light, oxygen, pH, concentration, and metal ions) on its stability in aqueous media using a stability-indicating HPLC-UV method. First-order kinetics fitted its degradation under all tested conditions except light and oxygen. In both cases, the established models in chemical kinetics were inappropriate and upgraded with the Weibull model. Metal ions and acidic conditions had the main destabilizing effect on vitamin D3 in aqueous media, but these solutions were successfully stabilized after the addition of ethylenediaminetetraacetic acid (EDTA), ascorbic acid, and citric acid, individually and in combination. EDTA showed the most significant stabilizing effect. Synergism among antioxidants was not observed. Our findings on vitamin D3 instability in aqueous media also correlated with its instability in commercial products. Vitamin D3 aqueous products require proper stabilization, thereby signifying the importance and contribution of the obtained results to the formulation of stable and quality products.
48
Hanif, Muhammad, Vesh Chaurasiya, Muqeet Wahid, Muhammad Basharat, Saima Naz, Shakila Mirza, Qurat-ul-ain Aslam, Mishaal Tariq, and Alina Butt. "Comparison of Flurbiprofen Tablets Available In Pakistani Market and Their Absorption Studies." Pakistan Journal of Pharmaceutical Research 1, no. 2 (June 1, 2015): 62. http://dx.doi.org/10.22200/pjpr.2015262-69.
Full textAbstract:
AbstractThe aim of this present work was to compare different parameters of various brands of flurbiprofen tablets collected from different retail pharmacies in the local market of Pakistan. Four brands A, B, C and D were tested for weight variation, hardness, friability, disintegration dissolution, HPLC assay and in vitro absorption studies in rabbit skin, stomach and intestine by using the prepacked Column RT 250-4.6 Purospher® STAR RP-18 end capped (5 µm) and acetonitrile, phosphate buffer (pH 3.7) as mobile phase in the ratio of 1:1. Flurbiprofen was detected at 265 nm at the flow rate of 1 ml/min. Brand B was considered as reference. Similarity factor (f2) of brand B and C and brand B & D was found to be 61 and 51 and dissimilarity factors (f1) values were 5 and 9 respectively in same dissolution medium. Model dependent methods First order, Hixon crowell and Weibull model were used. The method was found to be sensitive and linear in the range of 10 to 700 ppm with 0.999 coefficient of correlation. Everted sac absorption studies of selected formulation showed 50% of drug absorption from stomach in first 3 hours, 21% through intestine and very negligible through skin.
49
GUILLOU, SANDRINE, and JEANNE-MARIE MEMBRÉ. "Inactivation of Listeria monocytogenes, Staphylococcus aureus, and Salmonella enterica under High Hydrostatic Pressure: A Quantitative Analysis of Existing Literature Data." Journal of Food Protection 82, no. 10 (September 23, 2019): 1802–14. http://dx.doi.org/10.4315/0362-028x.jfp-19-132.
Full textAbstract:
ABSTRACT High hydrostatic pressure processing (HPP) is a mild preservation technique, and its use for processing foods has been widely documented in the literature. However, very few quantitative synthesis studies have been conducted to gather and analyze bacterial inactivation data to identify the mechanisms of HPP-induced bacterial inactivation. The purpose of this study was to conduct a quantitative analysis of three-decimal reduction times (t3δ) from a large set of existing studies to determine the main influencing factors of HPP-induced inactivation of three foodborne pathogens (Listeria monocytogenes, Staphylococcus aureus, and Salmonella enterica) in various foods. Inactivation kinetics data sets from 1995 to 2017 were selected, and t3δ values were first estimated by using the nonlinear Weibull model. Bayesian inference was then used within a metaregression analysis to build and test several models and submodels. The best model (lowest error and most parsimonious) was a hierarchical mixed-effects model including pressure intensity, temperature, study, pH, species, and strain as explicative variables and significant factors. Values for t3δ and ZP associated with inactivation under HPP were estimated for each bacterial pathogen, with their associated variability. Interstudy variability explained most of the variability in t3δ values. Strain variability was also important and exceeded interstudy variability for S. aureus, which prevented the development of an overall model for this pathogen. Meta-analysis is not often used in food microbiology but was a valuable quantitative tool for modeling inactivation of L. monocytogenes and Salmonella in response to HPP treatment. Results of this study could be useful for refining quantitative assessment of the effects of HPP on vegetative foodborne pathogens or for more precisely designing costly and labor-intensive experiments with foodborne pathogens.
50
Gupta, Ritu, Yuan Chen, Mahua Sarkar, and Huan Xie. "Surfactant Mediated Accelerated and Discriminatory In Vitro Drug Release Method for PLGA Nanoparticles of Poorly Water-Soluble Drug." Pharmaceuticals 15, no. 12 (November 29, 2022): 1489. http://dx.doi.org/10.3390/ph15121489.
Full textAbstract:
In vitro drug release testing is an important quality control tool for formulation development. However, the literature has evidence that poly-lactide-co-glycolide (PLGA)-based formulations show a slower in vitro drug release than a real in vivo drug release. Much longer in vitro drug release profiles may not be reflective of real in vivo performances and may significantly affect the timeline for a formulation development. The objective of this study was to develop a surfactant mediated accelerated in vitro drug release method for the PLGA nanoparticles (NPs) of a novel chemotherapeutic agent AC1LPSZG, a model drug with a poor solubility. The Sotax USP apparatus 4 was used to test in vitro drug release in a phosphate buffer with a pH value of 6.8. The sink conditions were improved using surfactants in the order of sodium lauryl sulfate (SLS) < Tween 80 < cetyltrimethylammonium bromide (CTAB). The dissolution efficiency (DE) and area under the dissolution curve (AUC) were increased three-fold when increasing the CTAB concentration in the phosphate buffer (pH 6.8). Similar Weibull release kinetics and good linear correlations (R2~0.99) indicated a good correlation between the real-time in vitro release profile in the phosphate buffer (pH 6.8) and accelerated release profiles in the optimized medium. This newly developed accelerated and discriminatory in vitro test can be used as a quality control tool to identify critical formulation and process parameters to ensure a batch-to-batch uniformity. It may also serve as a surrogate for bioequivalence studies if a predictive in vitro in vivo correlation (IVIVC) is obtained. The results of this study are limited to AC1LPSZG NPs, but a similar consideration can be extended to other PLGA-based NPs of drugs with similar properties and solubility profiles.