Leather and Footwear Journal

Volume 24, no 4

Contents
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EFFECTS OF MIDSOLE HARDNESS AND INSOLE MATERIALS ON SHOCK ABSORPTION IN PROTECTIVE BOOTS
- Pages 249-257
  Lei QIN^*, Jiachen FAN, Xiuxing WANG
  - Institute of Quartermaster Engineering & Technology, Systems Engineering Institute, Beijing 100010, China
  ABSTRACT. This study aimed to determine the influence of varying midsole hardness and insole materials on cushioning performance of protective boots. Twenty healthy male participants performed running tests with six conditions of protective boots, varying in midsole hardness (50 shore C-soft, 60 shore C-medium, 70 shore C-hard) and insole material (Thermoplastic Polyurethane, Polyurethane). The first peak vertical ground reaction force (1^st PVGRF), impact duration (ID), and average vertical loading rate (AVLR) were measured by a force plate. The subjective cushioning evaluation was also conducted using a visual analogue scale. The results showed that midsole hardness had a significant effect on ID (P = 0.048, η²p = 0.151) and AVLR (P = 0.048, η²p = 0.301) but not on 1^st PVGRF (P = 0.222, η²p = 0.076). The ID was longer and the AVLR was lower for hard shoes compared to soft shoes. Insole materials had no significant effect on any of the impact variables (P > 0.05). Subjective evaluations indicated that the medium-hardness shoes received the highest cushioning scores among the three hardness levels. The findings suggest that midsole hardness influences impact duration and loading rate, while insole materials do not significantly affect the shock absorption performance of protective boots.
  
  KEY WORDS: protective boots, midsole hardness, insole material, shock absorption
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COLLAGEN AND KERATIN HYDROLYSATES AS VALUABLE ADDITIVES FOR RENEWABLE NEW PRODUCTS IN CIRCULAR ECONOMY
- Pages 259-266
  Carmen GAIDĂU^*, Maria STANCA, Demetra SIMION, Mariana Daniela BERECHET, Cosmin-Andrei ALEXE
  - National Institute for Textiles and Leather, 16, Lucretiu Patrascanu st., 030508, Bucharest, 3, Romania, emails: carmen.gaidau@icpi.ro; maria.stanca@icpi.ro; demetra.simion@incdtp.ro; daniela.berechet@icpi.ro; cosmin.alexe@icpi.ro
  ABSTRACT. Collagen and keratin-based waste represents a valuable biomass resource with still insufficiently exploited potential. The leather industry and sheep breeding activity generate important protein waste based on collagen and keratin which at world level amounts to 5.6 million and 1 million tonnes, respectively, every year. The processing of protein-based waste through water or chemical-enzymatic hydrolysis, allows the refinement of the molecular weights and distribution with different potential functionalities for versatile new products with applications in industry (deliming agents, filling and finishing additives), agriculture, medicine, or other fields. The versatile properties as a function of hydrolysis process were shown by analyses of protein degradation (ATR-FTIR spectroscopy), molecular weight distribution (SDS-PAGE electrophoresis) and particle size distribution (DLS analyses). The specific molecular weight distribution of collagen and keratin hydrolysates after hydrolysis at 100°C and 130°C was highlighted, thus proving the potential of refining the compositions for different applications with ecological impact. The collagen hydrolysis at 100°C leads to fragmentation of large molecules into small molecules meanwhile the temperature of 130°C favors the increase of medium size population of peptides, in agreement with SDS-PAGE electrophoresis results. Instead, the small molecules of keratin were doubled by hydrolysis at 130°C, in good correlation with ATR-FTIR determination of AI/AA ratios.
  
  KEY WORDS: protein hydrolysates, molecular distribution, collagen, keratin
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IMPLEMENTATION OF THE PRINCIPLES OF BIOECONOMY IN LEATHER PRODUCTION
- Pages 267-278
  Maryna ZHALDAK^1*, Valentyna POLIUHA¹, Оlena MOKROUSOVA^{1, 2}, Anna OLESHKO², Olena BUDIAKOVA², Taras KARAVAYEV¹
  - ¹State University of Trade and Economics, Ukraine, maryna070992@ukr.net
  - ²Kyiv National University of Technologies and Design, Ukraine
  ABSTRACT. Bioeconomy is a promising approach to addressing resource conservation and negative environmental impacts. Given the high potential of bioeconomy principles, many countries worldwide are focused on developing plans with a perspective up to 2050. The main sectors where bioeconomy principles are applied globally include agriculture, light industry, and bioenergy. In Ukraine, the bioeconomy strategy is developing at a slower pace. However, the developed 10R bioeconomy strategies can be adapted in Ukraine, considering the processing industry’s development trends. Given the active development of agriculture in Ukraine, including many raw hides (cattle cow, bovine, etc.), the tasks of processing animal hides are relevant. It is known that a large amount of water, energy resources, and chemicals are used in such processing. A significant amount of waste is also generated, which can be used to implement bioeconomy principles. The study optimized the use of raw materials and chemicals by reducing or reusing water and solid leather production waste. It was found that the principles of R2 (Reduce), R3 (Reuse), R8 (Recycle), and R9 (Recover) can be implemented in leather production. The principles of R8 and R3, through the processing of biogenic raw materials and reducing the use of chemicals at the stages of leather production, respectively, have the highest efficiency before implementation.
  
  KEY WORDS: bioeconomy, leather, raw hide, water and solid wastes, technological processing
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INDUSTRIAL WORKERS’ EFFICIENCY IN INDIAN SUBCONTINENT: A MACHINE LEARNING MODEL APPROACH
- Pages 279-284
  Sadman SADIK^1*, Syed Mahedi HASEN²
  - ¹Khulna University of Engineering and Technology, Bangladesh, sadmansdk@gmail.com
  - ²Rajshahi University of Engineering and Technology, Bangladesh, syedmahedihasen207@gmail.com
  ABSTRACT. The growing popularity of machine learning offers exciting possibilities for real-world applications. Since worker efficiency directly impacts a company’s bottom line, especially for small and medium businesses (SMEs), implementing these tools can be a game-changer. By improving worker efficiency, machine learning can help SMEs minimize losses and drive growth. This research explores the potential of AI model not to replace workers but to uplift them. In this study, we try to find out the industrial workers’ efficiency, especially in the Leather & Textiles industries, based on some parameters like expertise, education, salary, working hour, standard minute value (SMV), working position, key performance indicators (KPI) etc. The study investigates different regression models for predicting worker efficiency. Here we compare six models including Random Forest and XG Boost, using metrics like Mean Squared Error to find the best performing model. XG Boost and Histogram Gradient Boosting show the best results in predicting worker efficiency. XG Boost achieved high accuracy (R-squared around 0.78) with low errors (MSE around 0.01). Light GBM came in a close third, while Random Forest and Ada Boost did poorly. Machine learning techniques like XG Boost can significantly improve worker efficiency in the Indian subcontinent in leather-textile industries.
  
  KEY WORDS: workers performance, industrial worker augmentation, data driven efficiency
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COMPOSITE MATERIALS FOR LIMB PROSTHETICS LINERS
- Pages 285-294
  Ivan IUNGIN^*, Olena MOKROUSOVA
  - Kyiv National University of Technologies and Design, 2 Mala Shiyanovska, Kyiv 01011, iunginivan@gmail.com, olenamokrousova@gmail.com
  ABSTRACT. Managing the soft tissues of residual limbs in individuals with lower limb amputations presents a significant challenge. Unlike the plantar tissues of an intact foot, the soft tissues of the residual limb are unaccustomed to mechanical loading. Consequently, the loads transferred to the residual limb by the prosthetic socket can frequently lead to the development of ulcers and other skin issues including infection. This review aimed to comprehensively analyze current research about perspective materials used for prosthetic liners. The most promising materials used for liners includes composite materials, leather and combining phase change materials. Optimizing the material composition of prosthetic liners requires a comprehensive approach that considers both mechanical and surface properties.
  
  KEY WORDS: prosthetic liners, composite materials, limb
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THE INVESTIGATION OF A 17TH CENTURY PARCHMENT DOCUMENT
- Pages 295-300
  Cristina CARŞOTE^{1, 2*}, Iuliana ȘTIRBU¹
  - ¹National Museum of Romanian History, Bucharest, Romania, 12 Calea Victoriei, Bucharest, Romania, criscarsote@yahoo.com
  - ²National Research & Development Institute for Textiles and Leather, ICPI Division, 93 Ion Minulescu st., Bucharest, Romania
  ABSTRACT. This study presents the investigation of a chrisov written on parchment, issued by Ștefan Lupu, the prince (voivode) of Moldavia (1659-1661), in 1660, from the collection of the National Museum of History of Romania (MNIR), in Bucharest. By using an analytical protocol based on corroboration of macroscopic and microscopic observations with the attenuated total reflection infrared spectrometry (ATR-FTIR) and X-ray fluorescence spectroscopy (XRF), information concerning parchment, inks and pigments were obtained. The Ștefan Lupu’ chrisov is written on high quality goat parchment, matte, smooth, velvety, and it presents only a few manufacturing defects. ATR-FTIR analysis revealed a well-preserved structure of the collagen molecules, with a low level of hydrolytic decay. According to the XRF results, ferogallic and golden inks were used to write the Chrisov text whereas the ornaments were painted with vermilion pigment (for red color), verdigris pigment (for green color), Co-based pigment (for blue color) and fine gold powder. Both inks and pigments show a very good state of conservation.
  
  KEY WORDS: workKEY WORDS: parchment, degradation, inks, pigments, ATR-FTIR, XRF
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