Poly(Lactic Acid)/Zinc/Alginate Complex Material: Preparation and Antimicrobial Properties

The aim of this study was to investigate an antimicrobial and degradable composite material consisting of melt-blown poly(lactic acid) nonwoven fabrics, alginate, and zinc. This paper describes the method of preparation and the characterization of the physicochemical and antimicrobial properties of the new fibrous composite material. The procedure consists of fabrication of nonwoven fabric and two steps of dip-coating modification: (1) impregnation of nonwoven samples in the solution of alginic sodium salt and (2) immersion in a solution of zinc (II) chloride. The characterization and analysis of new material included scanning electron microscopy (SEM), specific surface area (SSA), and total/average pore volume (BET). The polylactide/alginate/Zn fibrous composite were subjected to microbial activity tests against colonies of Gram-positive (Staphylococcus aureus), Gram-negative (Escherichia coli) bacterial strains, and the following fungal strains: Aspergillus niger van Tieghem and Chaetomium globosum. These results lay a technical foundation for the development and potential application of new composite as an antibacterial/antifungal material in biomedical areas.

Coda Waves for Health Monitoring of Composites Under Low-Velocity Impact

Coda waves have been shown to be sensitive to lab-controlled defects such as very small holes in fibrous composite material. In the real world, damages are subtler and more irregular. The main objective of this work is to investigate coda wave capability to detect low-velocity impact damages. The emphasis is to detect the presence of barely visible impact damages using ultrasonic waves. Detection of incipient damage state is important as it will grow over the life of the structure. Differential features, previously used in similar work, have been utilized to detect realistic impact damages on carbon fiber composites. Quasi-isotropic composite laminates were subjected to low-velocity impact energy ranging from 2J to 4.5J. Two differential features reported could be used detect the presence of damage. It is also observed that ply orientation can be a deterministic factor for indicating damages. The size and shape of the impact damage has been characterized using ultrasonic C-scans. Results indicate that coda waves can be used for the detection of damage due to low-velocity impact.

MODEL OF DEFORMATION OF FIBROUS MATERIALS OF MULTIDIRECTIONAL REINFORCEMENT WITH NONORIENTED FIBERS

A model of deformation of multidirectional reinforcement fibrous materials with differently oriented fibers is proposed. The solution to the problem is built in two stages. At the first stage, the known properties of fibers and binder are used to determine the effective thermoelastic properties and stress-strain state of the subsystem with fibers oriented in a certain way relative to the main coordinate system. It is based on stochastic differential equations of the physically nonlinear theory of elasticity using the method of conditional moments. At the second stage, using a given distribution function based on the Voigt scheme, a model of deformation of the entire system is constructed from the calculated properties of the subsystems. Strain curves are obtained for simple loading, and the deformation of materials at uniform orientation of fibers is investigated. It was found that a fibrous composite material with differently oriented fibers in a macrovolume is isotropic, and its effective thermoelastic constants substantially depend on the volumetric content of fibers.

Disposal of waste products from fibrous composite material

The article proposes a method of processing fiberglass to obtain a fibrous component used as reinforcing filler for the manufacture of secondary composite materials. The obtained analytical dependencies can be used to develop the design of the mill elements, as well as to optimize the grinding process When disposing of products made of fibrous composite material, the following scheme is proposed. The proposed analytical method for determining the modes of the grinding process solves the problem of choosing the preferred parameters of the mill operation depending on its functional dimensions and properties of components in a fibrous secondary composite material.

A New Paper-Based Microfluidic Device for Improved Detection of Nitrate in Water

In this paper, we report a simple and inexpensive paper-based microfluidic device for detecting nitrate in water. This device incorporates two recent developments in paper-based technology suitable for nitrate detection and has an optimized microfluidic design. The first technical advancement employed is an innovative fibrous composite material made up of cotton fibers and zinc microparticles that can be incorporated in paper-based devices and results in better nitrate reduction. The second is a detection zone with an immobilized reagent that allows the passage of a larger sample volume. Different acids were tested—citric and phosphoric acids gave better results than hydrochloric acid since this acid evaporates completely without leaving any residue behind on paper. Different microfluidic designs that utilize various fluid control technologies were investigated and a design with a folding detection zone was chosen and optimized to improve the uniformity of the signal produced. The optimized design allowed the device to achieve a limit of detection and quantification of 0.53 ppm and 1.18 ppm, respectively, for nitrate in water. This accounted for more than a 40% improvement on what has been previously realized for the detection of nitrate in water using paper-based technology.

Microencapsulation of Cannabidiol in Liposomes as Coating for Cellulose for Potential Advanced Sanitary Material

The microencapsulation of the cannabidiol and its integration into the tampon can eliminate vaginal inflammation, which at the same time lead to relaxation of the abdominal muscles. The tampon, which contains the active substance cannabidiol (CBD), was developed as an advanced fibrous composite for sanitary application. The active substances were microencapsulated, and, as a carrier, liposomes micro/nano capsules were used. The CBD liposome formulation was analyzed by particle size, polydispersity index, zeta potential, and encapsulation efficiency. Particle size of the CBD liposome liquid formulation was increased by 19%, compared to the liposome liquid formulation and the encapsulation efficiency of CBD in liposome particles, which was 90%. The CBD liposome formulation was applied to cellulose material. The composition of the fibrous composite material was evaluated by Fourier transform infrared spectroscopy, the fiber morphology was analyzed by scanning electron spectroscopy, while the bioactive properties were assessed by antioxidant efficiency, antimicrobial properties, and desorption kinetics. CBD liposome functionalized tampons have both antioxidant and antimicrobial properties. Antimicrobial properties were more pronounced against Gram-positive bacteria. The desorption kinetics of the CBD liposome immobilized on the surface of the composite material was studied using antioxidant activity in the desorption bath. The prepared CBD liposome functionalized tampon additionally shows higher biodegradability compared to references. This high-quality, biodegradable sanitary material based on microencapsulated CBD components as a functional coating provides a platform for many different applications besides medical textiles, also for packaging, pharmaceuticals, paper and wood-based materials, etc.

Microstructural Hyperelastic Characterization of Brain White Matter in Tension

Axons as microstructural constituent elements of brain white matter are highly oriented in extracellular matrix (ECM) in one direction. Therefore, it is possible to model the human brain white matter as a unidirectional fibrous composite material. A micromechanical finite element model of the brain white matter is developed to indirectly measure the brain white matter constituents’ properties including axon and ECM under tensile loading. Experimental tension test on corona radiata conducted by Budday et al. 2017 [1] is used in this study and one-term Ogden hyperelastic constitutive model is applied to characterize its behavior. By the application of genetic algorithm (GA) as a black box optimization method, the Ogden hyperelastic parameters of axon and ECM minimizing the error between numerical finite element simulation and experimental results are measured. Inverse analysis is conducted on the resultant optimized parameters shows high correlation of coefficient (>99%) between the numerical and experimental data which verifies the accuracy of the optimization procedure. The volume fraction of axons in porcine brain white matter is taken to be 52.7% and the stiffness ratio of axon to ECM is perceived to be 3.0. As these values are not accurately known for human brain white matter, we study the material properties of axon and ECM for different stiffness ratio and axon volume fraction values. The results of this study helps to better understand the micromechanical structure of the brain and micro-level injuries such as diffuse axonal injury.