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Agnese Carino, Christian Ludwig, Antonio Cervellino, Elisabeth Müller, Andrea Testino
The experimental data on calcium phosphates formation were collected in dilute solution at constant pH (7.40) and temperature (37.0 °C) at different levels of ionic strength (IS). The evolution of the solid phase formation is described in detail using a thermodynamic-kinetic model. The thermodynamic model takes into account all relevant chemical species as well as Posner's clusters; the kinetic model, based on the discretized population balance approach, accounts for the solid formation from solution. The experimental data are consistent with an initial formation of dicalcium phosphate dihydrate (DCPD, brushite), which dominates the nucleation rate, and its rapid transformation into octacalcium phosphate (OCP) or hydroxyapatite (HA), which dominates the growth rate...
May 17, 2018: Acta Biomaterialia
Hayam Mahmoud Lotfy, Yasmin Mohammed Fayez, Shereen Mostafa Tawakkol, Nesma Mahmoud Fahmy, Mostafa Abd El-Atty Shehata
Several spectrophotometric techniques were recently conducted for the determination of binary mixtures of clotrimazole (CLT) and dexamethasone acetate (DA) without any separation procedure. The methods were based on generation of ratio spectra of mixture then applying simple mathematic manipulation. The zero order absorption spectra of both drugs could be obtained by the constant center (CC) method. The concentration of both CLT and DA could be obtained by constant value via amplitude difference (CV-AD) method depending on ratio spectra, Ratio difference (RD) method where the difference between the amplitudes at two wavelengths (ΔP) on the ratio spectra could eliminate the contribution of the interfering substance and bring the concentration of the other, and the derivative ratio (DD1 ) method where the derivative of the ratio spectra was able to determine the drug of interest without any interference of the other one...
May 10, 2018: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Johannes Scheiblauer, Stefan Scheiner, Martin Joksch, Barbara Kavsek
A combined experimental/theoretical approach is presented, for improving the predictability of Saccharomyces cerevisiae fermentations. In particular, a mathematical model was developed explicitly taking into account the main mechanisms of the fermentation process, allowing for continuous computation of key process variables, including the biomass concentration and the respiratory quotient (RQ). For model calibration and experimental validation, batch and fed-batch fermentations were carried out. Comparison of the model-predicted biomass concentrations and RQ developments with the corresponding experimentally recorded values shows a remarkably good agreement for both batch and fed-batch processes, confirming the adequacy of the model...
May 17, 2018: Journal of Theoretical Biology
Jagpreet Chhatwal, Qiushi Chen, Rakesh Aggarwal
Oral direct-acting antiviral agents have revolutionized treatment of hepatitis C virus (HCV) infection. Nonetheless, barriers exist to elimination of HCV as a public health threat including low uptake of treatment, limited budget allocations for HCV treatment, and low awareness rates of HCV status among infected people. Mathematical modeling provides a systematic framework to analyze and compare potential solutions and elimination strategies by simulating the HCV epidemic under different conditions. Such models evaluate impact of interventions in advance of implementation...
June 2018: Infectious Disease Clinics of North America
Ali R Jalalvand, Sirous Ghobadi, Hector C Goicoechea, Hui-Wen Gu, Esmael Sanchooli
In this work, voltammetric data recorded at a glassy carbon electrode (GCE) were separately used to investigate the interactions of entacapone (Comtan, CAT) with human serum albumin (HSA). Then, an augmented data matrix was constructed by the combination of voltammetric and spectroscopic data and simultaneously analysed by multivariate curve resolution-alternating least squares (MCR-ALS) to obtain more information about CAT-HSA interactions. The absence of rotational ambiguities in results obtained by MCR-ALS was verified with the help of MCR-BANDS and we confirmed that the results were unambiguous and reliable...
May 16, 2018: Bioelectrochemistry
Tajudeen A Oyehan, Ibrahim O Alade, Aliyu Bagudu, Kazeem O Sulaiman, Sunday O Olatunji, Tawfik A Saleh
The optical properties of blood play crucial roles in medical diagnostics and treatment, and in the design of new medical devices. Haemoglobin is a vital constituent of the blood whose optical properties affect all of the optical properties of human blood. The refractive index of haemoglobin has been reported to strongly depend on its concentration which is a function of the physiology of biological cells. This makes the refractive index of haemoglobin an essential non-invasive bio-marker of diseases. Unfortunately, the complexity of blood tissue makes it challenging to experimentally measure the refractive index of haemoglobin...
April 30, 2018: Computers in Biology and Medicine
Nicolas Tarlier, Ian Soulairol, Noelia Sanchez-Ballester, Gilles Baylac, Adrien Aubert, Philippe Lefevre, Bernard Bataille, Tahmer Sharkawi
Mannitol is commonly used as a pharmaceutical excipient for tablets; the most widely used oral dosage form for drug delivery. For tableting, mannitol is provided in two different forms: native crystals and textured particles. In order to optimize its formulation, a good understanding of the mechanical behavior mechanism of mannitol is necessary. Thus, the aim of this study is to evaluate the deformation mechanism of native mannitol crystals presenting different particle sizes. Pharmaco-technical and compression studies were performed using mannitol with different mean diameters (160 µm, 50 µm and 25 µm)...
May 16, 2018: International Journal of Pharmaceutics
Rui Li, Xiaodong Zhang, Hanzhe Li, Liming Zhang, Zhufeng Lu, Jiangcheng Chen
Brain control technology can restore communication between the brain and a prosthesis, and choosing a Brain-Computer Interface (BCI) paradigm to evoke electroencephalogram (EEG) signals is an essential step for developing this technology. In this paper, the Scene Graph paradigm used for controlling prostheses was proposed; this paradigm is based on Steady-State Visual Evoked Potentials (SSVEPs) regarding the Scene Graph of a subject's intention. A mathematic model was built to predict SSVEPs evoked by the proposed paradigm and a sinusoidal stimulation method was used to present the Scene Graph stimulus to elicit SSVEPs from subjects...
May 16, 2018: Brain Research
Manfred Henrich, Svenja Scheffold, Werner Hecht, Manfred Reinacher
Analysis of clonality is gaining importance in diagnosing lymphomas in veterinary medicine. Usually, PCR for the analysis of antigen receptor rearrangement (PARR) is followed by electrophoretic separation of the PCR products. Aim of this study was to test the feasibility of HRM for the assessment of clonality in B-cell lymphomas of cats. High resolution melting analysis differentiates PCR products by their different melting point using the decrease in fluorescence of an intercalating dye during melting of the PCR product...
June 2018: Veterinary Immunology and Immunopathology
Carlos Bonazzola, Alejandro Hnilo, Marcelo Kovalsky, Jorge Tredicce
The passively Q-switched, self-pulsing all-solid-state laser is a device of widespread use in many applications. Depending on the condition of saturation of the absorber, which is easy to adjust, different dynamical regimes are observed: continuous-wave emission, stable oscillations, period doubling bifurcations, chaos, and, within some chaotic regimes, extreme events (EEs) in the form of pulses of extraordinary intensity. These pulses are sometimes called "dissipative optical rogue waves." The mechanism of their formation in this laser is unknown...
March 2018: Physical Review. E
Guillermo Rodrigo
Gene expression programs in living cells are highly dynamic due to spatiotemporal molecular signaling and inherent biochemical stochasticity. Here we study a mechanism based on molecule-to-molecule variability at the RNA level for the generation of bursts of protein production, which can lead to heterogeneity in a cell population. We develop a mathematical framework to show numerically and analytically that genes regulated post transcriptionally by small RNA molecules can exhibit such bursts due to different states of translation activity (on or off), mostly revealed in a regime of few molecules...
March 2018: Physical Review. E
Benjamin Steinegger, Alessio Cardillo, Paolo De Los Rios, Jesús Gómez-Gardeñes, Alex Arenas
The containment of epidemic spreading is a major challenge in science. Vaccination, whenever available, is the best way to prevent the spreading, because it eventually immunizes individuals. However, vaccines are not perfect, and total immunization is not guaranteed. Imperfect immunization has driven the emergence of antivaccine movements that totally alter the predictions about the epidemic incidence. Here, we propose a mathematically solvable mean-field vaccination model to mimic the spontaneous adoption of vaccines against influenzalike diseases and the expected epidemic incidence...
March 2018: Physical Review. E
Enrico Gavagnin, Christian A Yates
Persistence of motion is the tendency of an object to maintain motion in a direction for short time scales without necessarily being biased in any direction in the long term. One of the most appropriate mathematical tools to study this behavior is an agent-based velocity-jump process. In the absence of agent-agent interaction, the mean-field continuum limit of the agent-based model (ABM) gives rise to the well known hyperbolic telegraph equation. When agent-agent interaction is included in the ABM, a strictly advective system of partial differential equations (PDEs) can be derived at the population level...
March 2018: Physical Review. E
Katrina Kully-Martens, Jacqueline Pei, Julie Kable, Claire D Coles, Gail Andrew, Carmen Rasmussen
BACKGROUND: Individuals with fetal alcohol spectrum disorders (FASD) experience deficits in behavior, cognition, and academic functioning resulting from prenatal alcohol exposure (PAE). Although receiving intervention for developmental disabilities is a strong protective factor against negative outcomes in FASD, intervention research in this population is in its infancy. AIMS: The purpose of this study was to replicate and extend a mathematics intervention, the Math Interactive Learning Experience (MILE) program, which was developed in the USA specifically for children with FASD...
May 15, 2018: Research in Developmental Disabilities
Kevin Breslin, John Joseph Wade, KongFatt Wong-Lin, Jim Harkin, Bronac Flanagan, Harm Van Zalinge, Steve Hall, Matthew Walker, Alexei Verkhratsky, Liam McDaid
A biophysical model that captures molecular homeostatic control of ions at the perisynaptic cradle (PsC) is of fundamental importance for understanding the interplay between astroglial and neuronal compartments. In this paper, we develop a multi-compartmental mathematical model which proposes a novel mechanism whereby the flow of cations in thin processes is restricted due to negatively charged membrane lipids which result in the formation of deep potential wells near the dipole heads. These wells restrict the flow of cations to "hopping" between adjacent wells as they transverse the process, and this surface retention of cations will be shown to give rise to the formation of potassium (K+) and sodium (Na+) microdomains at the PsC...
May 18, 2018: PLoS Computational Biology
Haggai Schermann, Erin Craig, Einat Yanovich, Itay Ketko, Gary Kalmanovich, Ran Yanovich
CONTEXT:   The heat-tolerance test (HTT) is a screening tool for secondary prevention of exertional heat illness by the Israel Defense Forces. To discern participant tolerance, recruits are exposed to intermediate environmental and exercise stresses, and their physiological responses, core temperature, and heart rate are monitored. When their physiological measures rise at a higher rate or exceed the upper levels of absolute values compared with other participants, heat intolerance (HI) is diagnosed...
April 2018: Journal of Athletic Training
Ville Jäntti, Tuomo Ylinen, Narayan Puthanmadam Subramaniyam, Kotoe Kamata, Arvi Yli-Hankala, Pasi Kauppinen, Eila Sonkajärvi
Purpose - Anesthesiologists have increasingly started to use EEG based indexes to estimate the level and type of unconsciousness. However, the physiology and biophysics are poorly understood in anesthesiological literature. Methods - EEG was recorded from electrodes on the surface of head, including scalp, as well as DBS (deep brain stimulation) electrodes implanted deep in the brain. Mathematical modeling with a realistic head model was performed to create illustrative images of the sensitivity of electrode montages...
May 18, 2018: International Journal of Radiation Biology
Silvana Arreghini, Laura de Cabo, Roberto José María Serafini, Alicia Fabrizio de Iorio
Decomposition of plant debris is an important process in determining the structure and function of aquatic ecosystems. The aims were to find a mathematic model fitting the decomposition process of Schoenoplectus californicus shoots containing different Zn concentrations; compare the decomposition rates; and assess metal accumulation/mobilization during decomposition. A litterbag technique was applied with shoots containing three levels of Zn: collected from an unpolluted river (RIV) and from experimental populations at low (LoZn) and high (HiZn) Zn supply...
July 3, 2018: International Journal of Phytoremediation
Rachel Walker, Jonathan D Schoenfeld, Shari Pilon-Thomas, Jan Poleszczuk, Heiko Enderling
The potential for local radiation therapy to elicit systemic (abscopal) anti-tumor immune responses has been receiving a significant amount of attention over the last decade. We recently developed a mathematical framework designed to simulate the systemic dissemination of activated T cells among multiple metastatic sites. This framework allowed the identification of non-intuitive patterns of T cell redistribution after localized therapy, and offered suggestions as to the optimal site to irradiate in order to increase the magnitude of an immune-mediated abscopal response...
September 2017: Convergent Science Physical Oncology
Lianchun Yu, Zhou Shen, Chen Wang, Yuguo Yu
Selective pressure may drive neural systems to process as much information as possible with the lowest energy cost. Recent experiment evidence revealed that the ratio between synaptic excitation and inhibition (E/I) in local cortex is generally maintained at a certain value which may influence the efficiency of energy consumption and information transmission of neural networks. To understand this issue deeply, we constructed a typical recurrent Hodgkin-Huxley network model and studied the general principles that governs the relationship among the E/I synaptic current ratio, the energy cost and total amount of information transmission...
2018: Frontiers in Cellular Neuroscience
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