Experimental Study and Mechanism Analysis of Paraffin/Sisal Composite Phase Change Energy Storage Fiber Prepared by Vacuum Adsorption Method.

Sisal fiber exhibits a fibrous and porous structure with significant surface roughness, making it highly suitable for storing phase change materials (PCMs). Its intricate morphology further aids in mitigating the risk of PCM leakage. This research successfully employs vacuum adsorption to encapsulate paraffin within sisal fiber, yielding a potentially cost-effective, durable, and environmentally friendly phase change energy storage medium. A systematic investigation was carried out to evaluate the effects of sisal-to-paraffin mass ratio, fiber length, vacuum level, and negative pressure duration on the loading rate of paraffin. The experimental results demonstrate that a paraffin loading rate of 8 wt% can be achieved by subjecting a 3 mm sisal fiber to vacuum adsorption with 16 wt% paraffin for 1 h at -0.1 MPa. Through the utilization of nano-CT imaging enhancement technology, along with petrographic microscopy, this study elucidates the mechanism underlying paraffin storage within sisal fiber during vacuum adsorption. The observations reveal that a substantial portion of paraffin is primarily stored within the pores of the fiber, while a smaller quantity is firmly adsorbed onto its surface, thus yielding a durable phase change energy storage medium. The research findings contribute to both the theoretical foundations and the available practical guidance for the fabrication and implementation of paraffin/sisal fiber composite phase change energy storage mediums.

Multidirectional Associative Memory Neural Network Circuit Based on Memristor.

Multidirectional associative memory neural network(MAMNN) is a direct extension of bidirectional associative memory neural network, which can handle multiple associations. In this work, a circuit of MAMNN based on memristor is proposed, which simulates the complex associative memory behavior more in line with the brain mechanism. Firstly, the basic associative memory circuit is designed, which is mainly composed of memristive weight matrix circuit, adder module and activation circuit. It realizes the associative memory function of single-layer neurons input and single-layer neurons output, so that the information can be transmitted unidirectionally between double-layer neurons. Secondly, on this basis, an associative memory circuit with multi-layer neurons input and single-layer neurons output is realized, which makes information transfer unidirectionally between multi-layer neurons. Finally, several identical circuit architectures are extended, and they are combined into a MAMNN circuit through the feedback connection from the output to the input, which realizes the bidirectional transmission of information between multi-layer neurons. Pspice simulation shows that: 1) When single-layer neurons are selected to input data, the circuit can associate data from other multi-layer neurons, realizing one-to-many associative memory function in the brain. 2) When multi-layer neurons are selected to input data, the circuit can associate the target data and realize the many-to-one associative memory function in the brain. The MAMNN circuit is applied to the field of image processing, which can associate and restore damaged binary images, showing strong robustness.

High drug-loading system of hollow carbon dots-doxorubicin: preparation, in vitro release and pH-targeted research.

Hollow carbon dots (HCDs), as drug carriers, and doxorubicin (DOX), as a model drug, were selected to prepare a HCDs-DOX-loading system. First, HCDs were prepared by a hydrothermal method and characterized by transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), and nuclear magnetic resonance (13C NMR), UV-vis absorption, Fourier-transform infrared (FT-IR) and X-ray photoelectron spectroscopies (XPS). The HCDs were then used to load DOX. The drug-loading system of HCDs-DOX was characterized by zeta potential measurements, and UV-vis absorption and fluorescence spectroscopies. We then studied the drug loading, formation mechanism, cytotoxicity, in vitro release and pH-targeted properties. HCDs-DOX was found to have a high drug (DOX)-loading ratio (∼42.9%) and better sustained pH targeted-release and lower cytotoxicity than those of DOX. In the HCDs-DOX system, interactions between the HCDs and DOX were electrostatic resulting in the formation of -N[double bond, length as m-dash]C-via the coupling of -NH2 (on HCDs) and -C[double bond, length as m-dash]O (on DOX). In vitro release of HCDs-DOX conformed to the Weibull model and Fick diffusion, consistent with that of free DOX. We report, for the first time, that the: (i) functional groups on the HCD surfaces (not their hollow structure) play a key role in drug loading; (ii) the carrier (HCDs) did not change the in vitro release model or mechanism of DOX before and after loading by the HCDs.