scholarly journals Biodegradation Pattern of Glycopolymer Based on D-Mannose Oligomer and Hydroxypropyl Acrylate

Polymers ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 704 ◽  
Author(s):  
Ana-Maria Pană ◽  
Valentin Ordodi ◽  
Gerlinde Rusu ◽  
Vasile Gherman ◽  
Geza Bandur ◽  
...  
Keyword(s):  
Weight Ratio ◽  
Synthetic Polymers ◽  
Radical Copolymerization ◽  
Microbial Consortia ◽  
Nutrient Source ◽  
Scanning Calorimetry ◽  
Sugar Moiety ◽  
The Past ◽  
Significant Research ◽  
Copolymerization Kinetics

Glycopolymers are polymers with sugar moieties which display biodegradable and/or biocompatible character. They have emerged as an environmentally-friendly solution to classical synthetic polymers and have attracted significant research interest in the past years. Herein, we present the synthesis of a D-mannose based glycopolymer with biodegradable features. The glycopolymer was synthesized by radical copolymerization between a D-mannose oligomer bearing polymerizable double bonds and 2-hydroxypropyl acrylate, in a weight ratio of 1:2. The copolymerization kinetics was investigated by differential scanning calorimetry (DSC) and the activation energy of the process was comparatively assessed by Kissinger–Akahira–Sunose and Flynn–Wall–Ozawa methods. The obtained glycopolymer displayed good thermal behavior, fact proven by thermogravimetrical (TG) analysis and it was submitted to biodegradation inside a bioreactor fed with water from the Bega River as the source of microbial inoculum. The glycopolymer sample degraded by approximately 60% in just 23 days. The biodegradation pattern of the glycopolymer was successfully fitted against a modified sigmoidal exponential function. The kinetic model coefficients and its accuracy were calculated using Matlab and the correlation coefficient is more than promising. The changes inside glycopolymer structure after biodegradation were studied using TG and FTIR analyses, which revealed that the sugar moiety is firstly attacked by the microbial consortia as nutrient source for proliferation.

scholarly journals Latest Developments in Insect Sex Pheromone Research and Its Application in Agricultural Pest Management

Insects ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 484
Author(s):  
Syed Arif Hussain Rizvi ◽  
Justin George ◽  
Gadi V. P. Reddy ◽  
Xinnian Zeng ◽  
Angel Guerrero
Keyword(s):  
Sex Pheromone ◽  
Pest Management ◽  
Interdisciplinary Approach ◽  
Pheromone Biosynthesis ◽  
Insect Pheromones ◽  
Agricultural Pest ◽  
Practical Applications ◽  
The Past ◽  
Significant Research ◽  
Recent Developments

Since the first identification of the silkworm moth sex pheromone in 1959, significant research has been reported on identifying and unravelling the sex pheromone mechanisms of hundreds of insect species. In the past two decades, the number of research studies on new insect pheromones, pheromone biosynthesis, mode of action, peripheral olfactory and neural mechanisms, and their practical applications in Integrated Pest Management has increased dramatically. An interdisciplinary approach that uses the advances and new techniques in analytical chemistry, chemical ecology, neurophysiology, genetics, and evolutionary and molecular biology has helped us to better understand the pheromone perception mechanisms and its practical application in agricultural pest management. In this review, we present the most recent developments in pheromone research and its application in the past two decades.

scholarly journals Chitosan-Based Nanocomposite Polymeric Membranes for Water Purification—A Review

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2091
Author(s):  
Angela Spoială ◽  
Cornelia-Ioana Ilie ◽  
Denisa Ficai ◽  
Anton Ficai ◽  
Ecaterina Andronescu
Keyword(s):  
Water Purification ◽  
Antioxidant Activities ◽  
Low Cost ◽  
Synthetic Polymers ◽  
Water Systems ◽  
Polymeric Membranes ◽  
Wastewater Purification ◽  
Toxic Compounds ◽  
The Past ◽  
Materials Used

During the past few years, researchers have focused their attention on developing innovative nanocomposite polymeric membranes with applications in water purification. Natural and synthetic polymers were considered, and it was proven that chitosan-based materials presented important features. This review presents an overview regarding diverse materials used in developing innovative chitosan-based nanocomposite polymeric membranes for water purification. The first part of the review presents a detailed introduction about chitosan, highlighting the fact that is a biocompatible, biodegradable, low-cost, nontoxic biopolymer, having unique structure and interesting properties, and also antibacterial and antioxidant activities, reasons for using it in water treatment applications. To use chitosan-based materials for developing nanocomposite polymeric membranes for wastewater purification applications must enhance their performance by using different materials. In the second part of the review, the performance’s features will be presented as a consequence of adding different nanoparticles, also showing the effect that those nanoparticles could bring on other polymeric membranes. Among these features, pollutant’s retention and enhancing thermo-mechanical properties will be mentioned. The focus of the third section of the review will illustrate chitosan-based nanocomposite as polymeric membranes for water purification. Over the last few years, researchers have demonstrated that adsorbent nanocomposite polymeric membranes are powerful, important, and potential instruments in separation or removal of pollutants, such as heavy metals, dyes, and other toxic compounds presented in water systems. Lastly, we conclude this review with a summary of the most important applications of chitosan-based nanocomposite polymeric membranes and their perspectives in water purification.

scholarly journals Physicochemical and Antifungal Properties of Clotrimazole in Combination with High-Molecular Weight Chitosan as a Multifunctional Excipient

Marine Drugs ◽  
2020 ◽  
Vol 18 (12) ◽  
pp. 591
Author(s):  
Bożena Grimling ◽  
Bożena Karolewicz ◽  
Urszula Nawrot ◽  
Katarzyna Włodarczyk ◽  
Agata Górniak
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Weight Ratio ◽  
Scanning Calorimetry ◽  
Minimal Inhibitory Concentrations ◽  
Dissolution Tests ◽  
Effective Combination ◽  
The Impact ◽  
High Molecular Weight Chitosan

Chitosans represent a group of multifunctional drug excipients. Here, we aimed to estimate the impact of high-molecular weight chitosan on the physicochemical properties of clotrimazole–chitosan solid mixtures (CL–CH), prepared by grinding and kneading methods. We characterised these formulas by infrared spectroscopy, differential scanning calorimetry, and powder X-ray diffractometry, and performed in vitro clotrimazole dissolution tests. Additionally, we examined the antifungal activity of clotrimazole–chitosan mixtures against clinical Candida isolates under neutral and acid conditions. The synergistic effect of clotrimazole and chitosan S combinations was observed in tests carried out at pH 4 on Candida glabrata strains. The inhibition of C. glabrata growth reached at least 90%, regardless of the drug/excipient weight ratio, and even at half of the minimal inhibitory concentrations of clotrimazole. Our results demonstrate that clotrimazole and high-molecular weight chitosan could be an effective combination in a topical antifungal formulation, as chitosan acts synergistically with clotrimazole against non-albicans candida strains.

scholarly journals Recent Advances in Zwitterionic Hydrogels: Preparation, Property, and Biomedical Application

Gels ◽  
2022 ◽  
Vol 8 (1) ◽  
pp. 46
Author(s):  
Sihang Liu ◽  
Jingyi Tang ◽  
Fangqin Ji ◽  
Weifeng Lin ◽  
Shengfu Chen
Keyword(s):  
Immune System ◽  
Polyethylene Glycol ◽  
Biomedical Applications ◽  
Biomedical Application ◽  
Synthetic Polymers ◽  
Human Environment ◽  
The Past ◽  
Recent Advances ◽  
Nonspecific Protein Adsorption ◽  
Anionic Groups

Nonspecific protein adsorption impedes the sustainability of materials in biologically related applications. Such adsorption activates the immune system by quick identification of allogeneic materials and triggers a rejection, resulting in the rapid failure of implant materials and drugs. Antifouling materials have been rapidly developed in the past 20 years, from natural polysaccharides (such as dextran) to synthetic polymers (such as polyethylene glycol, PEG). However, recent studies have shown that traditional antifouling materials, including PEG, still fail to overcome the challenges of a complex human environment. Zwitterionic materials are a class of materials that contain both cationic and anionic groups, with their overall charge being neutral. Compared with PEG materials, zwitterionic materials have much stronger hydration, which is considered the most important factor for antifouling. Among zwitterionic materials, zwitterionic hydrogels have excellent structural stability and controllable regulation capabilities for various biomedical scenarios. Here, we first describe the mechanism and structure of zwitterionic materials. Following the preparation and property of zwitterionic hydrogels, recent advances in zwitterionic hydrogels in various biomedical applications are reviewed.

A Conceptual Framework for Enterprise Interoperability

2015 ◽  
pp. 652-662
Author(s):  
Wided Guédria
Keyword(s):  
Conceptual Framework ◽  
Assessment Tool ◽  
Maturity Model ◽  
Automatic Assessment ◽  
Maturity Models ◽  
The Past ◽  
Enterprise Interoperability ◽  
Significant Research ◽  
Corrective Actions ◽  
Research Challenge

The obligation to become more competitive and effective in providing better products and services requires enterprises to transform from traditional businesses into networked businesses. One of the challenges faced by a network of enterprises is the development of interoperability between its members. Transformations in this context are usually driven by Enterprise Interoperability (EI) problems that may be faced. In order to quickly overcome these problems, enterprises need characterizing and assessing interoperability to be prepared to establish means for collaboration and initiate corrective actions before potential interoperability problems occur and then be obliged to make unprepared transformations that may be costly and induce unmanageable issues. This has become a significant research challenge over the past few years and maturity models have been developed in response to this challenge. In this paper we propose to extend a maturity model based on an ontological formalization of the interoperability domain. This will allow diagnosing interoperability problems when assessing EI and having a conceptual framework as basis for an automatic assessment tool.

scholarly journals Active Motion Control of a Knee Exoskeleton Driven by Antagonistic Pneumatic Muscle Actuators

Actuators ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 134
Author(s):  
Wei Zhao ◽  
Aiguo Song
Keyword(s):  
Sliding Mode ◽  
Weight Ratio ◽  
Practical Application ◽  
Active Motion ◽  
Pneumatic Muscle ◽  
The Past ◽  
Robotic Devices ◽  
Muscle Actuators ◽  
Further Development ◽  
Rehabilitation Robotic

The pneumatic muscle actuator (PMA) has been widely applied in the researches of rehabilitation robotic devices for its high power to weight ratio and intrinsic compliance in the past decade. However, the high nonlinearity and hysteresis behavior of PMA limit its practical application. Hence, the control strategy plays an important role in improving the performance of PMA for the effectiveness of rehabilitation devices. In this paper, a PMA-based knee exoskeleton based on ergonomics is proposed. Based on the designed knee exoskeleton, a novel proxy-based sliding mode control (PSMC) is introduced to obtain the accurate trajectory tracking. Compared with conventional control approaches, this new PSMC can obtain better performance for the designed PMA-based exoskeleton. Experimental results indicate good tracking performance of this controller, which provides a good foundation for the further development of assist-as-needed training strategies in gait rehabilitation.

Fabrication of a novel laser-processed NiTi shape memory microgripper with enhanced thermomechanical functionality

2012 ◽  
Vol 24 (8) ◽  
pp. 984-990 ◽  
Author(s):  
Matthew Daly ◽  
Andrew Pequegnat ◽  
Yunhong N Zhou ◽  
Mohammad I Khan
Keyword(s):  
Shape Memory ◽  
Processing Technique ◽  
Thermomechanical Properties ◽  
Nickel Titanium ◽  
Testing Methods ◽  
Scanning Calorimetry ◽  
Resistivity Measurements ◽  
Processed Material ◽  
Significant Research

The thermomechanical properties of nickel-titanium shape memory alloys have sparked significant research efforts seeking to exploit their exotic capabilities. Until recently, the performance capabilities of nickel-titanium devices have been inhibited by the retention of only one thermomechanical response. In this article, the application of a novel laser-processing technique is demonstrated to create a monolithic self-positioning nickel-titanium shape memory microgripper. Device actuation and gripping maneuvers were achieved by thermally activating processed material regions which possessed unique phase transformation onset temperatures and thermomechanical recovery characteristics. The existence of each thermomechanical material domain was confirmed through differential scanning calorimetry analysis. Independent thermomechanical recoveries of each embedded shape memory were captured using tensile testing methods. Deployment of each embedded shape memory was achieved using resistive heating, and in situ resistivity measurements were used to monitor progressive phase transformations.

A study of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) biofilms’ thermal and biodegradable properties reinforced with halloysite nanotubes

2018 ◽  
Vol 52 (23) ◽  
pp. 3199-3207 ◽  
Author(s):  
SM Kamrul Hasan ◽  
S Zainuddin ◽  
J Tanthongsack ◽  
MV Hosur ◽  
L Allen
Keyword(s):  
Petroleum Products ◽  
Halloysite Nanotubes ◽  
Synthetic Polymers ◽  
Soil Conditions ◽  
Solvent Casting ◽  
Casting Method ◽  
Scanning Calorimetry ◽  
Structural Applications ◽  
Biodegradation Process ◽  
Biodegradable Properties

The aim of this study is to investigate and optimize the performance of a promising biopolymer, poly (3-hydroxybutyrate-co-3-hydroxyvalerate) which can potentially replace non-biodegradable synthetic polymers derived from toxic petroleum products. Poly (3-hydroxybutyrate-co-3-hydroxyvalerate) biofilms were prepared using solvent casting method, and its thermal properties were determined using thermogravimetric and differential scanning calorimetry techniques. Also, the durability and biodegradability of these films were studied by keeping the samples in water and Alabama soil conditions for various lengths of time. Our results showed that the thermal and moisture resistance of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) biopolymer can be enhanced significantly with the addition of low halloysite nanotubes concentrations. Also, the biodegradation process of the poly (3-hydroxybutyrate-co-3-hydroxyvalerate) films was faster with the addition of halloysite nanotubes attributed to the accelerated microbial microorganism reaction in the soil. This study led to cognize that the PHBV biopolymers added with halloysite nanotubes can be successfully used for various biomedical, industrial and structural applications, and then decompose at a desired faster rate afterward.

Magnetic Properties of Irradiated Nickel Ferrite Thermoplastic Natural Rubber Nanocomposite

2014 ◽  
Vol 879 ◽  
pp. 206-212 ◽  
Author(s):  
Sivanesan Appadu ◽  
Sahrim Hj. Ahmad ◽  
Chantara Thevy Ratnam ◽  
Meor Yahaya Razali ◽  
Moayad Husein Flaifel ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Thermal Properties ◽  
Natural Rubber ◽  
Weight Ratio ◽  
Xrd Analysis ◽  
Degree Of Crystallinity ◽  
Scanning Calorimetry ◽  
Magnetic Microstructure ◽  
Sem Image ◽  
Thermoplastic Natural Rubber

The effect of electron beam (EB) irradiation at different doses on the magnetic, microstructure, morphological and thermal properties of NiFe2O4/Thermoplastic Natural Rubber (TPNR) nanocomposite was investigated. The NiFe2O4/TPNR nanocomposite samples were prepared by using a Haake mixer in weight ratio of 12:88. The TPNR matrix consists of natural rubber (NR), liquid natural rubber (LNR) and high density polyethylene (HDPE) in weight ratio of 20:10:70. The samples were irradiated using a 2 MeV EB machine in doses from 0 - 200 kGy. Magnetic properties studied by using the vibrating sample magnetometer (VSM) at room temperature showed that the values of saturation magnetization (MS), remanence magnetization (MR) and the coercivity (HC) value increased with increasing doses of irradiation. The increase in MSand MRvalues is attributed to the increase in concentration of Fe3+ions at octahedral B-site and decrease of concentration at the tetrahedral A-site in the NiFe2O4cubic structure. X-ray diffraction (XRD) analysis of the samples showed that peak intensities decreased and the width of the peaks increased with increasing doses of irradiation. Scanning electron microscope (SEM) image of the nanocomposite cross section showed the presence of defects which is more visible with increasing doses of irradiation. In the case of thermal properties, differential scanning calorimetry (DSC) analysis showed that the crystallization temperature (Tc) and the degree of crystallinity (Xc) of the nanocomposite samples decreased with increasing doses of irradiation due to crosslinking of polymeric chains which hinders the growth of crystals.

Synthesis of Nanocrystalline CeO2 Using Mechanochemical Method: The Effect of Milling Time on the Particle Size

2006 ◽  
Vol 517 ◽  
pp. 105-110 ◽  
Author(s):  
Abdul Hadi ◽  
Iskandar Idris Yaacob ◽  
Cheah Seok Gaik
Keyword(s):  
Cerium Dioxide ◽  
Milling Time ◽  
Gas Adsorption ◽  
Weight Ratio ◽  
High Energy ◽  
Scanning Calorimetry ◽  
Characterization Methods ◽  
Energy Impact ◽  
Nanocrystalline Cerium Dioxide ◽  
Cerium Carbonate

Nanocrystalline cerium dioxide (CeO2) has been successfully synthesized by mechanochemical technique at 12, 24, 36, 48 and 60 hours milling times. The starting materials, hydrated cerium carbonate and sodium hydroxide, were mixed in a weight ratio of 4:1 and were milled in a planetary ball mill with ball to powder ratio of 10:1. The high energy impact forces provided by the milling media caused collision of starting materials and allowed the chemical reaction to occur thus produced nanocrystalline cerium dioxide. The products were characterized using a battery of characterization methods, including thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and gas adsorption-desorption measurement. The nanocrystalline CeO2 with 6.7 nm of crystallite size and specific surface area of 66.66 m2/g was obtained when the sample was milled for 60 hrs and they annealed in air at 350 oC. The result showed that the crystallinity of nanocrystalline CeO2 decreased with increasing milling time.

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