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This paper investigates delivery of encapsulated drug from poly lactic-co-glycolic micro-/nano-particles. Experimental data collected from about 50 papers are analyzed by machine learning algorithms including linear regression, principal component analysis, Gaussian process regression, and artificial neural networks. The focus is to understand the effect of drug solubility, drug molecular weight, particle size, and pH-value of the release matrix/environment on drug release profiles. The results obtained from machine learning is then used as guidelines for designing new in vitro experiments to examine dependence of drug release profiles on those four factors. It is interesting to see that indeed the results of the new in vitro experiments are in basic agreement with the results obtained from machine learning. [ABSTRACT FROM AUTHOR]

The development of wound-dressing materials has attracted significant research interests in recent years. With the advancement of nanofabrication, the application of nanoparticles (NPs) in drug delivery systems has become feasible. However, most existing work focuses on incorporation of metal, metal/semi-metal oxide, or organic particles into nanofiber scaffolds. There has been a lack of work on the incorporation of drug-encapsulated polymeric particles into nanofiber scaffolds. In this study, gentamicin-encapsulated poly-(lactic-co-glycolic acid) (PLGA) NPs were synthesized via a double emulsion solvent evaporation method. Electrospinning was used to incorporate gentamicin-encapsulated PLGA NPs into nanofiber scaffolds. Atomic force microscopy (AFM), dynamic light scattering, scanning electron microscopy (SEM), ultraviolet–visible spectroscopy (UV–vis), and an agar diffusion method were utilized to characterize the morphologies, release profiles, and antibacterial activities of various gentamicin-loaded PLGA NP-incorporated nanofiber scaffolds. The results indicated that the PLGA NPs had a spherical morphology with an average diameter of 130 nm. Purification of PLGA NPs was essential to eliminate the residual poly-(vinyl alcohol) (PVA) and to prevent particle agglomeration. The purified PLGA NPs were uniformly and individually incorporated into the polyurethane (PU)/ poly-(ethenyl oxide) (PEO) or PEO-only nanofiber scaffolds but nearly none into the PU-only fiber scaffolds. PEO served as a continuous phase in the PU/PEO mixture, which significantly improved the compatibility of PLGA NPs and PU, resulting in a well-dispersed distribution of PLGA NPs in the monolithic nanofiber scaffolds. Excellent antibacterial properties against Escherichia coli were found in both PU/PEO and PEO nanofiber scaffolds. This study of incorporating gentamicin-encapsulated PLGA NPs into fiber scaffolds provides insights for achieving successful incorporation of drug-encapsulated polymeric NPs into fiber scaffolds. This offers a promising microfabrication technology for delivery of therapeutic molecules with controlled release for biomedical applications. [ABSTRACT FROM AUTHOR]

Retrovirus capsid is a fullerene-like lattice consisting of capsid protein hexamers and pentamers. Mathematical models for the lattice structure help understand the underlying biological mechanisms in the formation of viral capsids. It is known that viral capsids could be categorized into three major types: icosahedron, tube, and cone. While the model for icosahedral capsids is established and well-received, models for tubular and conical capsids need further investigation. This paper proposes new models for the tubular and conical capsids based on an extension of the Capser-Klug quasi-equivalence theory. In particular, two and three generating vectors are used to characterize respectively the lattice structures of tubular and conical capsids. Comparison with published HIV-1 data demonstrates a good agreement of our modeling results with experimental data.

Existing problems of sewage treatment plants in small towns were summarized firstly, and then the developing trend of construction of sewage treatment plants in small towns was discussed from the aspects of project decision, site selection, design, processing technology and construction financing models. Finally, outlooks for its future development were proposed to provide reference for the construction of sewage treatment plants in small towns in future. [ABSTRACT FROM AUTHOR]

This paper presents quadratic finite-volume methods for elliptic and parabolic problems on quadrilateral meshes that use Barlow points (optimal stress points) for dual partitions. Introducing Barlow points into the finite-volume formulations results in better approximation properties at the cost of loss of symmetry. The novel ‘symmetrization’ technique adopted in this paper allows us to derive optimal-order error estimates in the H1- and L2-norms for elliptic problems and in the L∞ (H1)- and L∞ (L2)-norms for parabolic problems. Superconvergence of the difference between the gradients of the finite-volume solution and the interpolant can also be derived. Numerical results confirm the proved error estimates. [ABSTRACT FROM AUTHOR]

Abstract: This paper investigates convergence of the discontinuous finite volume method (DFVM) under minimal regularity assumptions on solutions of second order elliptic boundary value problems. Conventional analysis requires the solutions to be in Sobolev spaces . Here we assume the solutions are in and employ the techniques developed in Gudi (2010) to derive error estimates in a mesh-dependent energy norm and the -norm for DFVM. The theoretical estimates are illustrated by numerical results, which include problems with corner singularity and intersecting interfaces. [Copyright &y& Elsevier]

Abstract: An adaptive discontinuous finite volume method is developed and analyzed in this paper. We prove that the adaptive procedure achieves guaranteed error reduction in a mesh-dependent energy norm and has a linear convergence rate. Numerical results are also presented to illustrate the theoretical analysis. [Copyright &y& Elsevier]

In this paper we utilize affine biquadratic elements and a two-step temporal discretization to develop a finite volume element method for parabolic problems on quadrilateral meshes. The method is proved to have an optimal order convergence rate in L2(0, T; H1(Ω)) under the ‘asymptotically parallelogram’ mesh assumption. Numerical experiments that corroborate the theoretical analysis are also presented. [ABSTRACT FROM PUBLISHER]

Abstract: In this paper, we develop a finite volume element method with affine quadratic bases on right quadrangular prism meshes for three-dimensional elliptic boundary value problems. The optimal -norm error estimate of second order accuracy is proved under certain assumptions about the meshes. Numerical results are presented to illustrate the theoretical analysis. [Copyright &y& Elsevier]

This paper presents a family of numerical solvers for anisotropic subdiffusion problems in annuli and also cylindrical and spherical shells. The fractional order Caputo temporal derivative is discretized based on linear interpolation. The spatial Laplacian is discretized by utilizing Chebyshev and Fourier spectral collocation. Detailed discussion and useful formulas are presented for polar, cylindrical, and spherical coordinate systems. Numerical experiments along with a brief analysis are presented to demonstrate the accuracy and efficiency of these solvers. These solvers represent a continuation of our work in Tan and Liu (2020) and shall be useful for numerical simulations of subdiffusion problems in cellular cytoplasm and other similar settings. [ABSTRACT FROM AUTHOR]

This paper presents studies on modeling and algorithms for groundwater anomaly detection. Specifically, conductivity along with four other surrogates are used for identifying anomaly in groundwater, the one-class support vector machine (1-SVM) technique is utilized for model training, and real data from Colorado Water Watch is used for testing the model and algorithms. Design of code modules in Python is briefly discussed. Since groundwater contamination rarely happens in reality, we also use synthetic data from numerical simulations of flow and transport in porous media to test this model for anomaly detection. [ABSTRACT FROM AUTHOR]

This paper presents a lowest-order weak Galerkin (WG) finite element method for solving the Stokes equations on convex polygonal meshes. Constant vectors are used separately in element interiors and on edges to approximate fluid velocity, whereas constant scalars are used on elements to approximate the pressure. For the constant vector basis functions, their discrete weak gradients are established in a matrix space that is based on the C W 0 space (Chen and Wang, 2017), whereas their discrete weak divergences are calculated as elementwise constants. To circumvent the saddle-point problem, a reduced scheme for velocity is established by using three types of basis functions for the discretely divergence-free subspace. A procedure for subsequent pressure recovery is also developed. Error analysis along with numerical experiments on benchmarks are presented to demonstrate accuracy and efficiency of the proposed new method. • A simple but efficient new finite element method for Stokes flow. • The method applies to triangular, quadrilateral, and polygonal meshes in a unified way. • First ever use of H(div)-subspaces on polygons for Stokes flow. • Discretely divergence-free scheme and subsequent pressure recovery. • Numerical examples for Stokes flow on polygonal meshes. [ABSTRACT FROM AUTHOR]

This paper presents an efficient and robust numerical solver for anisotropic subdiffusion problems, which are important but not addressed directly in the literature. The Chebyshev spectral collocation method is utilized for discretization of the spatial Laplacian, whereas a linear interpolation is used for discretizing the fractional order Caputo temporal derivative. This solver is stable and catches the main features of subdiffusion. Numerical experiments are presented to demonstrate the accuracy and efficiency of this new solver. • Anisotropic subdiffusion problems. • An easy-to-use but efficient solver for subdiffusion problems. • Proof of unconditional stability of numerical method. • Numerical examples for anisotropic subdiffusion. [ABSTRACT FROM AUTHOR]

This paper presents a novel 2-field finite element solver for linear poroelasticity on convex quadrilateral meshes. The Darcy flow is discretized for fluid pressure by a lowest-order weak Galerkin (WG) finite element method, which establishes the discrete weak gradient and numerical velocity in the lowest-order Arbogast–Correa space. The linear elasticity is discretized for solid displacement by the enriched Lagrangian finite elements with a special treatment for the volumetric dilation. These two types of finite elements are coupled through the implicit Euler temporal discretization to solve poroelasticity problems. A rigorous error analysis is presented along with numerical tests to demonstrate the accuracy and locking-free property of this new solver. • A FE solver for poroelasticity that solves for the two primal variables. • The solver uses the least degrees of freedom, compared to other existing methods. • The solver is locking-free. • Well-organized and easy-to-understand rigorous analysis. [ABSTRACT FROM AUTHOR]

This paper develops novel finite element solvers for linear poroelasticity problems on quadrilateral meshes. These solvers are based on the primal formulations of linear elasticity and Darcy flow. Specifically, the fluid pressure and solid displacement are approximated by scalar- or vector-valued polynomials of degree k ≥ 0 separately in element interiors and on edges. The discrete weak gradients of these shape functions are established in the broken (vector- or matrix-version) Arbogast–Correa spaces for approximations of the classical gradients in the variational forms. These weak Galerkin spatial discretizations are combined with the implicit Euler or Crank–Nicolson temporal discretizations to develop locking-free numerical solvers that have optimal order (k + 1) convergence rates in pressure, velocity, displacement, stress, and dilation. Rigorous analysis is presented and illustrated by numerical experiments on popular test cases. [ABSTRACT FROM AUTHOR]

A new full-length acyltransferase cDNA was obtained from Taxus chinensis by homology-based cloning strategy. The cDNA has an open-reading frame of 1,275 nucleotides, which encodes 425 amino acids with a calculated molecular weight of 47,241 Da and an estimated pI value of 5.93. The deduced amino acid sequence resembles the sequences of other cloned acyltransferases (56-61% identity; 71-75% similarity) involved directly in taxol biosynthetic pathways. This cDNA was expressed in Escherichia coli using the expression vector pET32a(+). The expression band corresponds to the calculated mass plus the N-terminal fusion protein derived from the vector.