Research of the developed gel intracorneal colored implants for keratopigmentation based on various materials. Experimental study

Purpose. Evaluation of the impact of the developed intracorneal gel stained implants for keratopigmentation based on various materials on the donor human cornea during organotypic cultivation. Material and methods. Three experimental samples of intracorneal gel stained implants were investigated: sample 1 based on sodium hyaluronate with organic pigment, sample 2 based on collagen hydrolyzate with inorganic pigment, and sample 3 based on hydroxypropyl methylcellulose (HPMC) with organic pigment. To determine the toxicity of the studied implants the apoptosis of keratocytes was determined in cryostat sections of the cornea. The method of immunohistochemistry was used to study apoptosis. Scanning electron microscopy was used to visualize the corneal structures in the presence of implants. Results. During the investigation we showed that a gel implant based on a collagen hydrolyzate and a pigment with an inorganic toner (28% in the composition) causes a weak expression of the initiator proteins of apoptosis Caspasa 8 and Cytochrome C, and there is no expression of the BAX and effector proteins Caspasa 3/7. It was revealed that samples No. 1 and No. 3 undergo partial dissolution and washout from the intrastromal tunnel, sample No. 2 based on collagen hydrolyzate has a dense structure and remains in the corneal tunnel throughout the entire cultivation period, for at least 7 days, which is showed using an electron-scanning microscopy. The proposed collagen hydrolyzate gel implant can be considered compact and non-toxic. Conclusion. As a result of organotypic cultivation for 7 days showed the best results intracorneal colored implant № 2 based hydrolyzate of collagen and inorganic toner. Intracorneal colored implant based on collagen hydrolyzate has a more compact and dense structure than the accompanying experimental samples. Key words: keratopigmentation, aniridia, intracorneal colored implant.

Automated Inorganic Pigment Classification in Plastic Material Using Terahertz Spectroscopy

This paper presents an automatic classification of plastic material’s inorganic pigment using terahertz spectroscopy and convolutional neural networks (CNN). The plastic materials were placed between the THz transmitter and receiver, and the acquired THz signals were classified using a supervised learning approach. A THz frequency band between 0.1–1.2 THz produced a one-dimensional (1D) vector that is almost impossible to classify directly using supervised learning. This paper proposes a novel pre-processing of 1D THz data that transforms 1D data into 2D data, which are processed efficiently using a convolutional neural network. The proposed pre-processing algorithm consists of four steps: peak detection, envelope extraction, and a down-sampling procedure. The last main step introduces the windowing with spectrum dilatation that reorders 1D data into 2D data that can be considered as an image. The spectrum dilation techniques ensure the classifier’s robustness by suppressing measurement bias, reducing the complexity of the THz dataset with negligible loss of accuracy, and speeding up the network classification. The experimental results showed that the proposed approach achieved high accuracy using a CNN classifier, and outperforms 1D classification of THz data using support vector machine, naive Bayes, and other popular classification algorithms.

Manufacturing Cellulose Nanofibers Using the Water Jet Method and Their Applications

Sugino Machine Ltd. manufactures and sells equipment for cutting, washing, atomization, and fibrillation of objects using water jet technology. By applying this technology, cellulose nanofibers (CNFs) have been successfully and efficiently produced. The feature of CNFs manufactured by water jet is that the crystallinity and polymerization degree do not decrease. A drying method has also been developed because CNFs are obtained in the aqueous dispersion state. Herein, we present their use as particle dispersant and reinforcing filler for natural rubber (NR) as case studies of CNF aqueous dispersion applications. When CNFs was used as a particle dispersant, good dispersion of water-repellent TiO2, diamond powder and inorganic pigment was achieved. When CNFs was used as a filler for NR, a specific reinforcing effect was realized. As an example of CNF application as dry powders, their use with a resin additive is investigated. When CNF dry powders was used as a filler for resin, a specific reinforcing effect was realized.

Mengembalikan Kejayaan Industri Kerajinan Cadas Silakarang di Kabupaten Gianyar melalui Penerapan Teknologi Cadas Termokromik Buatan

Covid-19 pandemi affects most of craft industries, including the formerly fabulous Silakarang stone’s arts and crafts located in the Gianyar Regency, Bali Province. Environmental issues regarding to river basin ecological protection along Ubud and Sukawati Districts, the mining of basaltic stones from the river banks was restricted strictly by the government. Thus, the natural stones resources for the Silakarang crafts became more difficult to afford. Hence, todays the Silakarang stone craftsmen are more and more dependent on the so-called white stone of Yogya from Java Island. Artificial stone, composing of volcanic ashes, rice husk ash silica-carbon nanocomposite, Portland cement could be the solution the problem. The addition of thermochromic natural inorganic pigment to the mixture could improve their color and performance of the artificial stones. The implementation of the thermochromic artificial stones technology to solve the stone crafts problem was conducted through community service using the participatory action and learning system approuch. As results, the artificial thermochromic stone crafts and arts products could be well accepted by costumers and it impacted to better selling of the stone crafts. The craftsmen gained better income and the Silakarang stone arts and crafts enterprises could better survive among the pandemic time.

OPTIMIZATION OF PROCESS FOR PRODUCTION OF NANOCRYSTALLINE CELLULOSE AND ITS COMPOSITES

In this work, optimal and waste-free technologies were proposed for the production of nanocrystalline cellulose (NCC) and its composites with inorganic pigment, as well as semi-finished products containing aggregates of nanoparticles. The following optimal hydrolysis conditions were found: concentration of sulfuric acid 40 wt%, temperature 80°C, duration 1 h, acid/cellulose ratio 7. After hydrolysis stage, the hydrolyzed cellulose was washed, diluted with water and disintegrated to isolate individual nanoparticles. Then, the diluted NCC dispersion was evaporated to obtain a commercial product - concentrated NCC paste. In order to obtain a composite, the acid in the unwashed hydrolyzed cellulose was neutralized with calcium hydroxide to precipitate a white pigment, calcium sulfate. In addition, the spent acid and acidic washings were collected and treated with hydroxylapatite (HAP) to produce a valuable by-product, superphosphate (SUP), the sale of which significantly reduces the cost of the primary product, NCC. Contaminated water collected after washing, neutralization and evaporation was purified and returned to the technological cycle. To reduce the cost of production, such expensive process steps as disintegration and evaporation of diluted dispersion were eliminated, which made it possible to obtain cheap semi-finished products containing NCC aggregates or composite of NCC with inorganic calcium sulfate particles.

Photodegradation kinetics of alkyd paints: the influence of varying amounts of inorganic pigments on the stability of the synthetic binder

Nowadays, understanding the degradation processes of artworks exposed to outdoor conditions is essential in order to conserve these objects. In fact, the continuous climate changes risk to increasingly affecting their chemical-physical stability, especially for modern and contemporary ones. For this purpose, in this study, the kinetics of photo-oxidation processes occurring in synthetic binders and their stability in mixtures with different inorganic pigments were investigated. The aim was not only to characterize the different degradation reactions over time but to study the photodegradation kinetics according to the different pigments and pigment/binder ratio (P/BM) chosen. A total of 9 paint samples were prepared by mixing the inorganic pigments (artificial ultramarine blue, hydrated chromium oxide green, and cadmium yellow) with alkyd resin, in three different pigment/binder (P/BM) ratios: 1:2, 1:3, and 1:6. The paint samples were exposed to artificial sunlight for up to 1008 h, documented by optical 3D microscopy and analysed by Infrared Spectroscopy (ATR-FTIR) and colourimetry every 168 hours. The results obtained demonstrate that the degradation processes of alkyd resin are influenced by the different inorganic pigment used and its amount/concentration in the mixtures. Evaluation of these different deterioration mechanisms took into account the morphological/colour changes, the chemical reactions, and the physical properties of the materials. This study should contribute to the field of conservation-restoration, such as finding protection strategies for surfaces from degradation agents.