Leather and Footwear Journal

Volume 17, no 4

Contents
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Polycarbodiimide and polyurethane cross-linkers for leather finishing
- Pages 181-192
  Sholingur C. RAMKUMAR, Adhigan MURALI, Govindarajan PREETHI, Bangaru CHANDRASEKARAN, Palanivel SARAVANAN, Sellamuthu N. JAISANKAR*
  - CSIR-Central Leather Research Institute (CLRI), Adyar, Chennai-600 020, Tamil Nadu, India
  ABSTRACT. This review focuses on polyurethane and carboxylic acid-carbodiimide cross-linked systems for leather fi nishes. Recently, these cross-links have become very popular in leather finishing. The cross-links in leather finishes improve the strength properties of the finished leather, the excess of cross-links causes brittleness. The multifunctional carbodiimide cross-linkers are useful for leather surface properties improvement. The carbodiimide groups are sensitive to hydrolysis; life time of this functional group during polymerization is enhanced. Water dispersible isocyanates, polyurethane copolymers and polyisocyanate cross-links have applications in new technologies are discussed in this review.
  
  KEY WORDS: cross-linker, polycarbodiimide, diisocyanate, leather, polyurethane
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Differences in plantar pressure between the diabetic and healthy subjects
- Pages 193-198
  Rongtian LIU¹, Mingyu HU¹, Yiming GU², Hong LIN², Bo XU^1,3, Jiuping XU³, Jin ZHOU^1,4*
  - ¹National Engineering Laboratory for Clean Technology of Leather Manufacture, Sichuan University, Chengdu 610065, P.R.China, e-mail: zj_scu@qq.com
  - ²Guangdong Huizhou Quality & Measuring Supervision Testing Institute, Huizhou 516003, China
  - ³School of Business, Sichuan University, Chengdu 610065, P.R. China
  - ⁴Chengdu Anland Co., LTD, Chengdu 610065, P.R. China
  ABSTRACT. Since varied thresholds were reported in the literature and in what range of peak pressure is safe was not answered, the aim of this study was to compare the plantar pressure between the diabetic and healthy subjects and then to find the risk threshold of pressure for diabetic patients. 177 volunteers (83 diabetic patients and 94 control ones) were recruited and their plantar pressure were measured by the Emed pressure system. Plantar region was divided into seven regions: big toe, MTH1-5 and MF, under which mean pressure (kPa) was calculated. The results show that major variations existed and mean pressure of the patients was 2.5% lower than that of healthy counterparts; however, the law of differences between the diabetic patients and healthy ones in 3%, 50% and 96% percentile level could not be found. Overall, attention should be paid to changes in feet of diabetic patients, who must receive appropriate treatment when their mean pressure exceeds 100kPa (about 10N/cm²).
  
  KEY WORDS: diabetic feet, foot ulcers, mean pressure, diabetic peripheral neuropathy
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Statistical-mathematical processing of anthropometric foot parameters and establishing simple and multiple correlations. Part 1: statistical analysis of foot size parameters
- Pages 199-208
  Mirela PANTAZI^1*, Ana Maria VASILESCU¹, Aura MIHAI², Dana GURĂU¹
  - ¹INCDTP - Division: Leather and Footwear Research Institute, 93 Ion Minulescu, 031215 Bucharest, Romania, pantazimirela@yahoo.com
  - ²Gheorghe Asachi Technical University of Iasi, 67 Dimitrie Mangeron Blvd., Iasi, Romania, amihai@tex.tuiasi.ro
  ABSTRACT. The purpose of this study is to evaluate anthropometric parameters resulting from measurements by their statistical and mathematical processing. The study was conducted on a sample of 300 male subjects from three geographic regions of Romania: South (100 subjects), East (100 subjects) and Centre and West (100 subjects). The anthropometric data collected by 3D scanning of the left and right foot were grouped into four samples (South, East, Centre-West and Total) and the statistical indicators of characterization (arithmetic mean and standard deviation) and statistical variables (the minimum and maximum values, the amplitude and the coefficient of variation) were calculated for each variational sequence of the 20 anthropometric parameters studied. To verify the working hypothesis that there were no significant differences between left and right foot, Student's t-test and the Fisher (F) test were used to verify the variants. Both tests have shown that there are no significant differences between the left foot and the right foot for most anthropometric parameters. Samples for the four groups studied were based on the average of anthropometric parameters of the right and left foot. One-dimensional normal-size distribution for Foot Length (Lp) and Toe Girth (Pd) anthropometric parameters was verified. In this respect, the limits of the frequency classes, the centre of the class and the relative and absolute frequencies were established. This distribution is found in the commissioning of the shoe size series. For an optimal fit of the shoe, it is necessary to divide the size series into length and width classes.
  
  KEY WORDS: anthropometric parameters, foot, statistical indicators
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A novel extracellular keratinase from Exiguobacterium sp. Dg1: enzyme production and dehairing application
- Pages 209-216
  Jajang GUMILAR^1*, Lies Mira YUSIATI², Ambar PERTIWININGRUM², Tomoyuki NAKAGAWA³, Suharjono TRIATMOJO²
  - ¹Faculty of Animal Husbandry, Padjadjaran University, Bandung, Indonesia
  - ²Faculty ofAnimal Science, Gadjah Mada University, Yogyakarta, Indonesia
  - ³United Graduate School of Agricultural Science, Gifu University, Gifu, Japan
  ABSTRACT. In this research, we determined the optimum conditions for production of extracellular keratinase in Exiguobacterium sp DG1, and showed the possibility of application of the keratinase for sheep skin dehairing process. Strain DG1 showed the highest productivity of the keratinase activity during the growth in sheep hair meal (SHM) medium (pH 8) containing 10 g/L of SHM with aerobic incubation at 27°C for 48 hours. Moreover, dehairing process using an extracellular keratinase from strain DG1 decreased several index parameters in the treatment wastes. For example, in the treatment wastes using keratinase from strain DG1, COD and BOD values decreased drastically (82.1% and 73.7% respectively), compared to chemical dehairing process, and sulfide content was very low (less than 0.01 mg/L). These facts indicate that the extracellular keratinase from strain DG1 possesses a great potential of application for green leather tanning industry.
  
  KEY WORDS: keratinase, enzyme production, Exiguobacterium sp. DG1, dehairing
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Prescription variables for the medical footwear
- Pages 217-226
  Daniel PETCU
  - INCDTP - Division: Leather and Footwear Research Institute, 93 Ion Minulescu St., Bucharest, Romania, email: crispinian.ro@gmail.com
  ABSTRACT. Medical footwear is a medical device used in the conservative treatment of foot and lower limb pathomechanics. The standard EN ISO 9999:2016 - "Assistive products for person with disability-Classification and terminology", includes orthopedic shoes in the category of foot orthoses which are medical devices that encompass the whole or part of the foot, being divided in two categories: prefabricated or custom fabricated. According to the legal requirements, a custom fabricated device is based on a medical prescription containing the specific design characteristics as established by the medical practitioner. In many situations from clinical practice, the medical prescription does not contain the specific design characteristics but only some generic data such as the name and type of the orthopedic footwear. The purpose of this paper is to review the basic prescription variables of the medical footwear according to the experience from developed foot care systems.
  
  KEY WORDS: medical footwear, prescription variable
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The effect of foot type on the foot morphology and plantar pressure distributions of obese children
- Pages 227-234
  Shiyang YAN¹, Yue WANG², Ruoyi LI¹, Linshan ZHANG², Wuyong CHEN¹, Luming YANG¹
  - ¹Key Laboratory of Leather Chemistry and Engineering (Sichuan University), Ministry of Education, Chengdu, China
  - ²National Engineering Laboratory for Clean Technology of Leather Manufacture, Chengdu, China
  ABSTRACT. Obese children with flatfoot tolerate not only the excessive load, but also the foot structure deformity. The purpose of this study is to investigate the effect of different foot types on the foot morphology and plantar pressure distributions of obese children. Relative data of 30 obese children with flatfoot and another matched 30 obese children with normal arch foot were recorded. When the foot measures were normalized to the length of the foot, significantly lower instep height and longer instep circumference were found in obese children with flatfoot. Obese children with flatfoot displayed significantly greater pressure rate and force-time integral beneath the midfoot region, while displayed decreased load pattern beneath the 5^th metatarsal region. Small variations in foot morphology must be incorporated to the last design to meet the comfort and functionality requirements of specialized shoe for obese children with flatfoot. Obese children with flatfoot could be at an increased risk for midfoot injuries such as stress fractures.
  
  KEY WORDS: flatfoot, obese children, foot morphology, dynamic plantar pressure distribution
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Thermally resistant polymer composites reinforced with fibreglass
- Pages 235-240
  Mihai GEORGESCU, Maria SÖNMEZ, Mihaela NIŢUICĂ, Laura ALEXANDRESCU, Dana GURĂU
  - INCDTP - Division: Leather and Footwear Research Institute, 93 Ion Minulescu, Bucharest, Romania, mihai.georgescu@icpi.ro, mihai.georgesku@yahoo.com
  ABSTRACT. The aim of this paper was to obtain and characterize polymeric composites based on polyamide (PA) and polycarbonate (PC), reinforced with chemically activated surface fi breglass (FG), with advanced properties and temperature resistance. Polyamide was employed as the polymeric matrix, and the polycarbonate as disperse phase. As PA and PC are immiscible due to the polarity differences, a polyoxazoline compatibiliser was used. Afterwards, fibreglass was introduced in this composite. However, in order to obtain these properties, many variations of recipes had to be tested, with different concentrations of the components. The starting point was a mixture of 70% PA and 30% PC. The amount of compatibiliser varied up to 5%, and the FG amount, up to 30%. The characteristics of these polymeric composites with compatibiliser and simple and treated fibreglass were studied.
  
  KEY WORDS: polymeric composites, polyamide, polyethylene, fibreglass
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Method for determination of amino acid content in protein products for medical use
- Pages 241-254
  Gabriela MACOVESCU*, Ciprian CHELARU, Dana GURĂU
  - INCDTP - Division: Leather and Footwear Research Institute, 93 Ion Minulescu St., Bucharest, Romania, email: icpi@icpi.ro
  ABSTRACT. The paper presents a method for determination of amino acid content in collagen biomaterials for medical use produced in the Collagen Department of INCDTP - Division ICPI and its validation. The method has three stages: the first consists in hydrolysing the collagen biomaterial sample down to amino acids; the second step refers to derivatization of amino acids with N, O-bis (trimethylsilyl) trifl uoroacetamide (BSTFA) which is a silylation reagent; derivatized amino acids are detected using a mass spectrometer after gas chromatography. The method was validated to establish performance parameters and to check compliance with the intended purpose.
  
  KEY WORDS: collagen, amino acids, biomaterials
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Investigation of extracellular protease activity of two different extremely halophilic archaea isolated from raw hide
- Pages 255-262
  Fevziye Ișil KESBIÇ¹, Binnur MERIÇLI YAPICI^2*
  - ¹Kastamonu University, Central Research Laboratory, Kastamonu-37100,Turkey, ikesbic@kastamonu.edu.tr
  - ²Çanakkale Onsekiz Mart University, Faculty of Arts and Sciences, Department of Biology, Çanakkale-17020, Turkey, byapici@comu.edu.tr
  ABSTRACT. In this study, it was aimed to investigate extracellular protease activity of two diff erent extremely halophilic archaea and to identify them by using phenotypic and molecular methods. The haloarchaea were isolated from salted raw hide. The isolates were screened for production of protease enzyme and two isolates which have extracellular protease activity were selected. To identify the halophilic archaea, Gram staining procedure, antibiotic sensitivity tests and molecular methods were used. According to the 16S r-RNA molecular identifi cation results, isolate 1 identifi ed as Halococcus morrhuae JCM 8876 with % 99 sequence similarities and isolate 2 identifi ed as Natrinema pallidum 153 with % 99 sequence similarities. Azocasein was used as a substrate for measuring their proteases activities daily and their optimum activities were determined. H. morrhuae and N. pallidum showed daily maximum proteases activity on 6 and 4 days, respectively. According to the results of the study, it was found that proteases activity was related with diff erent reaction conditions. These conditions were detected as diff erent pH (4-11), temperature (4-70°C) and NaCl concentration (1-5 M) values. H. morrhuae showed the maximum activity at pH 9.5, 2M NaCl concentration and 50°C temperature and N. pallidum displayed the optimum activity at pH 9.0, 2M NaCl concentration and 40°C temperature.
  
  KEY WORDS: salted hide, haloarchaea, extracellular protease enzyme, 16S r-RNA sequence analysis
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