Leather and Footwear Journal

Volume 15, no 4

Contents
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Effect of UV Irradiation on Vegetable Tanned Leather
- Pages 219-228
  Yanping GAO^1,2, Shuang YANG^1,2, Xiaoyun JIAN^1,2, Lucreția MIU³, Carmen GAIDĂU³, Wuyong CHEN^1,2*
  - ¹Key Laboratory of Leather Chemistry and Engineering of the Ministry of Education, Sichuan University, Chengdu, 610065, P. R. China, wuyong.chen@163.com
  - ²National Engineering Laboratory for Clean Technology of Leather Manufacture, Sichuan University, Chengdu 610065, P. R. China
  - ³INCDTP - Leather and Footwear Research Institute, 93 Ion Minulescu St, sector 3, 031215, Bucharest, Romania
  ABSTRACT. This article aims at studying the influence of UV irradiation on vegetable tanned leather. Vegetable tanned leather was treated in QUV chamber (T = 50°C, irradiance = 1.77 W/mm²nm, ë_UVA=340 nm) for 0, 30, 60, 90, 120 and 150 hours. Then, these samples were evaluated by different analytical methods to get a whole picture of the leather during the irradiation. Micro hot table (MHT), differential scanning calorimetry (DSC) and thermogravimetry (TG) were used to evaluate the influences of UV irradiation on thermal behaviors. Damages to mechanical properties were also analyzed by a standard method. Fourier transform infrared spectroscopy (FT-IR) and optical microscopy were used to investigate the changes of structural and histological properties during aging process. With the extension of aging time, thermal stability was gradually reduced to lower values, including shrinkage temperature, thermal denaturation temperature, associated enthalpy and temperature for maximum decomposition rate. In addition, mechanical properties such as tensile strength, tear strength and elongation at break also gradually decreased. The FT-IR results showed that, during the aging process, amide I and amide II band of the tanned collagen gradually shifted to lower numbers, indicating an increasingly serious damage to the structure of the peptide chain, that corresponds to obvious fibril breakages which are also detected through optical microscopy.
  
  KEY WORDS: UV irradiation, vegetable tanned leather, aging
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Parameters Optimization of PID Controllers for Leather Manufacturing Process by Using Genetic Algorithms
- Pages 229-238
  Adrian-Bogdan HANCHEVICI^{1, 2}*, Sergiu-Adrian GUȚĂ¹
  - ¹INCDTP - Division Leather and Footwear Research Institute, Bucharest, Romania, email: guta.sergiu@icpi.ro
  - ²Politehnica University of Bucharest, Faculty of Automatic Control and Computers, Romania, email: adrian.hanchevici@upb.ro
  ABSTRACT. In this paper is proposed a control strategy for leather manufacturing process. This control strategy makes use of conventional PID control algorithms in combination with an evolutionary optimization technique, namely genetic algorithms. In order to find the parameters for the PID controllers, different performance indexes are provided to the genetic algorithms. In this study the proposed control strategy is used to control one process parameter, namely the pH value. Simulation results are presented. The results show performance improvement which proves that the proposed control strategy is able to make the closed-loop system behave as expected according to different given performance indexes.
  
  KEY WORDS: PID, genetic algorithms, leather manufacturing process
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Reliability Analysis of Footscan Plate System in Measurement of Plantar Pressure of Spastic Diplegia Children
- Pages 239-248
  Ting LI¹, Binqian LI¹, Wuyong CHEN¹, Jianxin WU², Bo XU¹, Jin ZHOU^1,2*
  - ¹National Engineering Laboratory for Clean Technology of Leather Manufacture, Sichuan University; Chengdu, P. R. China, zj_scu@qq.com
  - ²Science Lab, Zhejiang Red Dragonfly Footwear Co., LTD., Zhejiang Province, Wenzhou 325100, P. R. China
  ABSTRACT. This study was aimed at evaluating the reliability of Footscan plate system when measuring pressure in spastic diplegia children (CP). Eighteen CP and 36 typical developed counterparts (TD) with similar age, height and weight were recruited and their plantar pressure was measured in at least five trials. Three-mask model was applied and plantar regions were divided into: forefoot, mid foot and hind foot, under which peak pressure (PP) (N/cm2), relative pressure time integral (PTIrel) (%) and relative contact area (CArel) (%) were calculated. Coefficient of variance (CoV) and intra class coefficient (ICC) were explored for each variable and region. Our outcomes show that in terms of CP, with the increasing of test times, ICC of PP increased, while those of PTIrel and CArel were lowered; additionally, ICC of TD of each pressure variable successively improved. A similar tendency was found for CoV. Considering entire feet of CP and five measurements, reliability of CArel was the best in the three areas; whereas PP and PTIrel were demonstrated to be less reliable, except for the midfoot area. In contrast, reliabilities of TD were shown to be good for all pressure variables under all three regions. Overall, reliability of Footscan plate system in the study of CP was moderate in most variables and under most plantar regions. Thereby, by increasing the test times to no less than five, this protocol could be applied in the clinical and scientific investigation of CP children.
  
  KEY WORDS: spastic diplegia children, plantar pressure, reliability, intra class coefficient, coefficient of variance
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Collagen-Albumin-Gentamicin Hydrogels Usable for Infected Wound Healing
- Pages 249-256
  Georgeta PĂUNICĂ-PANEA^1,2, Mihaela Violeta GHICA³, Ştefania MARIN⁴, Ana-Maria ENE⁵, Maria Minodora MARIN⁴, Elena DĂNILĂ⁴, Cornelia NIȚIPIR^1,6, Mădălina Georgiana ALBU⁴, Ioan CRISTESCU¹
  - ¹Faculty of Medicine, Carol Davila University of Medicine and Pharmacy, Dionisie Lupu 37, 020022, Bucharest, Romania, paunica_laura@yahoo.com
  - ²Surgery Department, Sfantul Pantelimon Emergency Clinical Hospital, 340-342 Soseaua Pantelimon, 021659, Bucharest, Romania, paunica_laura@yahoo.com
  - ³Department of Physical and Colloidal Chemistry, Faculty of Pharmacy, Carol Davila, University of Medicine and Pharmacy 6, Traian Vuia Str., 020956, Bucharest, Romania, mihaelaghica@yahoo.com
  - ⁴Collagen Department, Leather and Footwear Research Institute, 93 Ion Minulescu Str., 031215, Bucharest, Romania, icpi@icpi.ro
  - ⁵Faculty of Applied Chemistry and Material Science, Politehnica University of Bucharest, 1-7 Polizu Str., 011061 Bucharest, Romania, anamariaene92@gmail.com
  - ⁶Elias Emergency University Hospital, 17, Marasti, Blv. 011461, Bucharest, Romania, nitipir2003@yahoo.com
  ABSTRACT. The aim of this study was to develop new hydrogels for infected wound treatment. The main components of hydrogels were two proteins, one fibrous (type I collagen in the form of gel) and one globular (albumin) in different ratios (10, 20 and 30%), and gentamicin was selected as an antibiotic drug model. The properties of the obtained hydrogels were estimated by rheological measurements and the corresponding lyophilized forms by water up-take capacity. The results showed that the promising hydrogels which can provide good absorbance and antimicrobial properties at the same time are the ones with maximum 20% albumin and 0.2% gentamicin and the in vitro tests are further recommended.
  
  KEY WORDS: hydrogels, collagen, rheology, albumin
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Effect of Ultrasound on the Dry Heat Behaviors of Cattlehide Collagen Fibers
- Pages 257-275
  Keyong TANG¹*, Wei TIAN¹, Fang WANG¹, Pengxiang JIA¹, Jinglong LIU¹, Mădălina Georgiana ALBU²
  - ¹College of Materials Science & Engineering, Zhengzhou University, Zhengzhou 450001, China, keyongtangzzu@yahoo.com
  - ²INCDTP - Division Leather and Footwear Research Institute, Collagen Department, 93 Ion Minulescu St., 031215, Bucharest, Romania
  ABSTRACT. In this paper, the dry heat behaviors of different cattlehide collagen fiber samples with and without power ultrasound process are studied, and such instruments as Thermal Platform Microscope, Differential Scanning Calorimetry (DSC) and Thermogravimetry (TG) are employed in the study. It is indicated that the dry heat behavior of the samples is slightly decreased because of the power ultrasound process. The reason why it is the case may be that part of the crystalline structure in the samples is destroyed by the power ultrasound process.
  
  KEY WORDS: ultrasound, dry heat behavior, cattlehide collagen fibers, tanning, retanning
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