Biopolymer-Based Materials from Polysaccharides: Properties, Processing, Characterization and Sorption Applications

Biopolymers are polymeric materials derived from biological sources. Due to their renewability, abundance, biodegradability and other unique properties such as high adsorption capabilities and ease of functionalization they have been investigated for several industrial applications including sorption. Polysaccharides especially cellulose, chitin and chitosan are important biopolymers because of their high abundance, wide distribution and low cost of production. This chapter provides an overview of properties, common processing methods, and material characterization of three commonly studied biopolymers namely cellulose, chitin and chitosan. It provides a thorough review on recent developments on utilization of cellulose, chitin, and chitosan-based materials for various sorption applications. Specifically, their application and efficiency in organic dye removal, heavy metals removal, oil and solvent spillage cleanup, and CO2 adsorption are presented and discussed

Formal Scenario-Based Testing of Autonomous Vehicles: From Simulation to the Real World

We present a new approach to automated scenario-based testing of the safety of autonomous vehicles, especially those using advanced artificial intelligence-based components, spanning both simulation-based evaluation as well as testing in the real world. Our approach is based on formal methods, combining formal specification of scenarios and safety properties, algorithmic test case generation using formal simulation, test case selection for track testing, executing test cases on the track, and analyzing the resulting data. Experiments with a real autonomous vehicle at an industrial testing facility support our hypotheses that (i) formal simulation can be effective at identifying test cases to run on the track, and (ii) the gap between simulated and real worlds can be systematically evaluated and bridged.Comment: 9 pages, 6 figures. Full version of an ITSC 2020 pape

Cellulose Dissolution in Ionic Liquid under Mild Conditions: Effect of Hydrolysis and Temperature

This study investigated the effect of acid hydrolysis of cellulose on its dissolution under mild conditions in ionic liquid, 1-butyl-3-methylimidazolium acetate/N,N-dimethylacetamide (BMIMAc/DMAc). Acid hydrolysis of high molecular weight (MW) cotton cellulose (DP > 4000) was carried out to produce hydrolyzed cotton (HC) samples for dissolution. The HC samples were characterized using gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA), and the dissolution process was monitored using polarized light microscopy (PLM). It was found that the drastic decrease of the MW of cellulose did not result in improvement of its dissolution at room temperature. As compared to original cotton cellulose, the high amount of undissolved fibers in HC solutions led to unstable rheological behavior of HC solutions. Agglomeration and inhomogeneous dispersion of HC, and increased crystallinity, in this case, likely made the diffusion of BMIMAc/DMAc more difficult to the inside of the polymeric network of cellulose at ambient temperature, thereby hindering the dissolution. However, increasing the temperature from room temperature to 35 °C and 55 °C, led to a significant improvement in cellulose dissolution. This phenomenon implies that reducing the MW of cellulose might not be able to improve its dissolution under certain conditions. During the dissolution process, the physical properties of cellulose including fiber aggregation status, solvent diffusivity, and cellulose crystallinity may play a critical role compared to the MW, while the MW may not be an important factor. This finding may help further understand the mechanism of cellulose dissolution and seek better strategies to dissolve cellulose under mild conditions for industrial applications

Utilization of Cellulose to Its Full Potential: A Review on Cellulose Dissolution, Regeneration, and Applications

As the most abundant natural polymer, cellulose is a prime candidate for the preparation of both sustainable and economically viable polymeric products hitherto predominantly produced from oil-based synthetic polymers. However, the utilization of cellulose to its full potential is constrained by its recalcitrance to chemical processing. Both fundamental and applied aspects of cellulose dissolution remain active areas of research and include mechanistic studies on solvent–cellulose interactions, the development of novel solvents and/or solvent systems, the optimization of dissolution conditions, and the preparation of various cellulose-based materials. In this review, we build on existing knowledge on cellulose dissolution, including the structural characteristics of the polymer that are important for dissolution (molecular weight, crystallinity, and effect of hydrophobic interactions), and evaluate widely used non-derivatizing solvents (sodium hydroxide (NaOH)-based systems, N,N-dimethylacetamide (DMAc)/lithium chloride (LiCl), N-methylmorpholine-N-oxide (NMMO), and ionic liquids). We also cover the subsequent regeneration of cellulose solutions from these solvents into various architectures (fibers, films, membranes, beads, aerogels, and hydrogels) and review uses of these materials in specific applications, such as biomedical, sorption, and energy uses

Antimicrobial sensitivity trend in blood culture positive enteric fever at Kathmandu Model Hospital

Background: For diagnosis of enteric fever, the culture of the organism from different body fluids is the gold standard. After diagnosis, it is important to treat with the right antibiotic before any complications can occur. The retrospective study is designed to explore the antibiotic sensitivity trend in blood culture positive typhoid fever cases and the extent of drug resistance before treatment is administered. Methods: A retrospective study was carried out for culture isolated enteric fever patients admitted in Kathmandu Model Hospital. The discharged records from January 2012 to December 2016 were analyzed. The patients above 15 years and with culture isolated enteric fever were included in the study. Results: One hundred fifty-nine strains of Salmonella typhi and paratyphi were isolated from Jan 2012 to Dec 2016 at Kathmandu Model Hospital. Out of 159 isolated, 125 (78.6%) were Salmonella typhi and 34 (21.4%) were paratyphi. Among them co-trimoxazole, chloramphenicol, ceftriaxone, cefotaxime, cefixime, and ofloxacin demonstrated 100% sensitivity. Similarly, amoxicillin sensitivity was 98.1% (n=156) while ciprofloxacin was sensitive in 6.3% (n=10), intermediately sensitive in 49.1% (n=78) and resistance in 44.7% (n=71).The newer quinolone levofloxacin showed 78.5% (n=11) sensitivity. Azithromycin was sensitive in 99.2% (n=132) of total isolated Salmonella species both typhi and paratyphi. Conclusions: A high degree of sensitivity was noted to chloramphenicol and co-trimoxazole, showing sensitivity has returned to conventional antibiotics. The drug-like ofloxacin is still the best responding drug in our contest whereas ciprofloxacin resistance is still high, but five years patterns show a trend of rollback of sensitivity

Cd(II) complexation with 1,1-dithiolate and nitrogen donors: synthesis, luminescence, crystal structure, and antifungal activity study

<div><p>A new luminescent complex of Cd(II) with 1,1-dicyanoethylene-2,2-dithiolate [i-MNT²⁻ = {S₂C : C(CN)₂}²⁻] with 1,3-diaminopropane (tn) and 4-methyl pyridine (γ-picoline) as secondary ligands has been synthesized and characterized on the basis of spectroscopy and single-crystal X-ray diffraction analysis. Single-crystal X-ray diffraction analysis reveals that cadmium(II) is five coordinate in a 1-D polymer. Biological screening effects <i>in vitro</i> of the synthesized complex has been tested against five fungi <i>Synchytrium endobioticum</i>, <i>Pyricularia oryzae</i>, <i>Helminthosporium oryzae</i>, <i>Candida albicans</i> (ATCC10231), and <i>Trichophyton mentagrophytes</i> by the disk diffusion method. A comparative study of inhibition zone values of K₂i-MNT·H₂O and {[Cd(tn)(iMNT)(4-MePy)]·4H₂O}_n (<b>1</b>) indicates that the complex exhibits antifungal activity, whereas K₂i-MNT·H₂O became silent on <i>S. endobioticum</i>, <i>P. oryzae</i>, <i>H. oryzae</i>, <i>C. albicans (ATCC10231),</i> and <i>T. mentagrophytes</i>.</p></div

Six-coordinate cadmium(II) complex containing a bridging dithiolate ligand: Synthesis, crystal structure and antifungal activity study

<div><p></p><p>A mixed ligand polymeric metal complex of Cd(II) has been prepared by reactions of Cd(NO₃)₂·4H₂O with 1,3-diaminopropane (tn) and potassium salt of 1,1-dicyanoethylene-2,2-dithiolate and characterized on the basis of spectroscopy and single-crystal X-ray diffraction analysis. Single-crystal X-ray diffraction analysis reveals that the Cd(II) complex crystallizes in monoclinic space group P 2₁/n with distorted octahedral coordination geometry. The Cd(II) complex was screened <i>in vitro</i> against fungal pathogens such as <i>Synchytrium endobioticum</i>, <i>Pyricularia oryzae</i>, <i>Helminthosporium oryzae</i>, <i>Candida albicans</i> (ATCC10231) and <i>Trichophyton mentagrophytes</i> by the disc diffusion method. The biological testing data of the primary ligand K₂i-MNT·H₂O and [Cd(tn)(i-MNT)]_n indicate that the complex exhibits fungistatic antifungal activity whereas K₂i-MNT·H₂O has no activity. The fungicidal properties of [Cd(tn)(i-MNT)]_n showed that the cadmium complex was more bioactive than the parent ligand.</p></div