Cationic chitosan derivatives as potential antifungals: A review of structural optimization and applications

The increasing resistance of pathogen fungi poses a global public concern. There are several limitations in current antifungals, including few available fungicides, severe toxicity of some fungicides, and drug resistance. Therefore, there is an urgent need to develop new antifungals with novel targets. Chitosan has been recognized as a potential antifungal substance due to its good biocompatibility, biodegradability, non-toxicity, and availability in abundance, but its applications are hampered by the low charge density results in low solubility at physiological pH. It is believed that enhancing the positive charge density of chitosan may be the most effective approach to improve both its solubility and antifungal activity. Hence, this review mainly focuses on the structural optimization strategy of cationic chitosan and the potential antifungal applications. This review also assesses and comments on the challenges, shortcomings, and prospect of cationic chitosan derivatives as antifungal therapy

Synthesis, characterization, and antifungal evaluation of novel 1,2,3-triazolium-functionalized starch derivative

1,2,3-Triazolium-functionalized starch derivative was obtained by straightforward quaternization of the synthesized starch derivative bearing 1,2,3-triazole with benzyl bromide by combining the robust attributes of cuprous-catalyzed azide-alkyne cycloaddition. These novel starch derivatives were characterized by FTIR, UV-vis, H-1 NMR, C-13 NMR, and elemental analysis. Their antifungal activities against Colletotrichum lagenarium, Watermelon fusarium, and Phomopsis asparagi were investigated by hypha measurement in vitro. The fungicidal assessment revealed that compared with starch and starch derivative bearing 1,2,3-triazole with inhibitory indices of below 15% at 1.0 mg/mL, 1,2,3-triazolium-functionalized starch derivative had superior antifungal activity with inhibitory rates of over 60%. Especially, the best inhibitory index of 1,2,3-triazolium-functionalized starch derivative against Colletotrichum lagenarium attained 90% above at 1.0mg/mL. The results obviously showed that quaternization of 1,2,3-triazole with benzyl bromide could effectively enhance antifungal activity of the synthesized starch derivatives. The synthetic strategy described here could be utilized for the development of starch as novel antifungal biomaterial. (C) 2017 Elsevier B.V. All rights reserved

Experimental Exploration of Influence of Recycled Polymer Components on Rutting Resistance and Fatigue Behavior of Asphalt Mixtures

Rutting and fatigue of asphalt pavements, as two important distresses, are significantly influenced by the properties of binders. This study aimed to improve the resistance of asphalt mixtures to permanent deformation and fatigue using two recycled waste-polymer components in recycled crumb rubber (CR) and polyethylene (PE). The assessed pavement properties of the modified asphalt mixtures were characterized by wheel tracking, uniaxial penetration, and four-point bending (4PB) tests. The wheel tracking test indicated that the integrated modification technique, by functionally incorporating PE and CR, enhanced the dynamic stability of the asphalt mixtures and that PE dosage was a key variable. From the uniaxial penetration test, it was revealed that the shear strength of the asphalt mixtures at high temperature could be improved by the integrated modification method, indicating the method’s potential to reduce the flow rutting of asphalt pavements. Meanwhile, both the CR and PE were shown to increase the cohesive behavior of the asphalt mixtures, with the friction angle value sensitive to PE dosage. The addition of PE reduced the fatigue life of the asphalt mixtures; the CR improved the PE-modified mixtures’ fatigue resistance. The findings from this study will be beneficial in developing sustainable and durable asphalt pavements, tailoring the reuse of different types of polymer wastes in asphalt pavements, and minimizing waste disposal at landfills

Synthesis and Antioxidant Activity of Cationic 1,2,3-Triazole Functionalized Starch Derivatives

In this study, starch was chemically modified to improve its antioxidant activity. Five novel cationic 1,2,3-triazole functionalized starch derivatives were synthesized by using "click" reaction and N-alkylation. A convenient method for pre-azidation of starch was developed. The structures of the derivatives were analyzed using FTIR and H-1 NMR. The radicals scavenging abilities of the derivatives against hydroxyl radicals, DPPH radicals, and superoxide radicals were tested in vitro in order to evaluate their antioxidant activity. Results revealed that all the cationic starch derivatives (2a-2e), as well as the precursor starch derivatives (1a-1e), had significantly improved antioxidant activity compared to native starch. In particular, the scavenging ability of the derivatives against superoxide radicals was extremely strong. The improved antioxidant activity benefited from the enhanced solubility and the added positive charges. The biocompatibility of the cationic derivatives was confirmed by the low hemolytic rate (<2%). The obtained derivatives in this study have great potential as antioxidant materials that can be applied in the fields of food and biomedicine

Maize microrna166 inactivation confers plant development and abiotic stress resistance

MicroRNAs are important regulators in plant developmental processes and stress responses. In this study, we generated a series of maize STTM166 transgenic plants. Knock-down of miR166 resulted in various morphological changes, including rolled leaves, enhanced abiotic stress resistance, inferior yield-related traits, vascular pattern and epidermis structures, tassel architecture, as well as abscisic acid (ABA) level elevation and indole acetic acid (IAA) level reduction in maize. To profile miR166 regulated genes, we performed RNA-seq and qRT-PCR analysis. A total of 178 differentially expressed genes (DEGs) were identified, including 118 up-regulated and 60 down-regulated genes. These DEGs were strongly enriched in cell and intercellular components, cell membrane system components, oxidoreductase activity, single organism metabolic process, carbohydrate metabolic process, and oxidation reduction process. These results indicated that miR166 plays important roles in auxin and ABA interaction in monocots, yet the specific mechanism may differ from dicots. The enhanced abiotic stress resistance is partly caused via rolling leaves, high ABA content, modulated vascular structure, and the potential changes of cell membrane structure. The inferior yield-related traits and late flowering are partly controlled by the decreased IAA content, the interplay of miR166 with other miRNAs and AGOs. Taken together, the present study uncovered novel functions of miR166 in maize, and provide insights on applying short tandem target mimics (STTM) technology in plant breeding

Coating effect of micro-sized droplets impacting on low temperature spherical particles

[EN] In this paper, the effect of spray droplets on the coating of cold spherical particles was studied.The microcapsule granulator produces micron-sized droplets to coat the spherical particles in cold storage, and the high-definition camera and precision balance are used to photograph and weigh the particles before and after the spraying. The droplets are obtained by using the image and data processing technology coating area and coating quality, the droplet coating effect was evaluated by a number of dimensionless parameters such as coating ratio and mass ratio.By orthogonal design experiment and uncertainty analysis, the effects of droplet size and flow rate, spherical particle temperature and diameter on coating effect were studied, and the effect of droplet group coating on low temperature spherical particles was obtained.The authors acknowledge Projects supported by the National Natural Science Foundation of China (Grant No. 31571906 & No.21506163).Wu, X.; Ma, X.; Xu, Q.; Li, Z.; Wang, R. (2018). Coating effect of micro-sized droplets impacting on low temperature spherical particles. En IDS 2018. 21st International Drying Symposium Proceedings. Editorial Universitat Politècnica de València. 1759-1766. https://doi.org/10.4995/IDS2018.2018.7734OCS1759176

Pressure drop characteristics of adjustable slotted distributor in fluidized bed

[EN] In this paper, a fluidized bed with a adjustable slotted gas distributor was used to study fluidization in a 230 mm×200 mm rectangular fluidized bed by adjusting the spacing between the two slotted gas distributors. The pressure drop of the distributor at different inlet gas velocities was obtained and the change law between pressure drop and distance between distributors was summarized. This study provides a theoretical basis for the application of adjustable slotted gas distributor fluidized bed.The authors acknowledge Projects supported by the National Natural Science Foundation of China (Grant No. 31571906 & No.21506163).Tong, Z.; Chaoran, L.; Qing, X.; Zhanyong, L.; W., J. (2018). Pressure drop characteristics of adjustable slotted distributor in fluidized bed. En IDS 2018. 21st International Drying Symposium Proceedings. Editorial Universitat Politècnica de València. 1751-1758. https://doi.org/10.4995/IDS2018.2018.7729OCS1751175

Protect sensitive information against channel state information based attacks

Channel state information (CSI) has been recently shown to be useful in performing security attacks in public WiFi environments. By analyzing how CSI is affected by the finger motions, CSI-based attacks can effectively reconstruct text-based passwords and locking patterns. This paper presents WiGuard, a novel system to protect sensitive on-screen gestures in a public place. Our approach carefully exploits the WiFi channel interference to introduce noise into the attacker's CSI measurement to reduce the success rate of the attack. Our approach automatically detects when a CSI-based attack happens. We evaluate our approach by applying it to protect text-based passwords and pattern locks on mobile devices. Experimental results show that our approach is able to reduce the success rate of CSI attacks from 92% to 42% for text-based passwords and from 82% to 22% for pattern lock

Find Me A Safe Zone:A Countermeasure for Channel State Information Based Attacks

Recently, channel state information (CSI) is shown to be an effective side-channel to perform attacks in public environments. Prior work has demonstrated that by analyzing how the CSI measurements of the wireless signal are affected by the mobile user's finger movements or gestures, an attacker can recover the user's input with a high success rate. Furthermore, the setup of this new attack is trivial, where the adversary only needs to place one or two malicious wireless devices near the target user. It would be difficult for many users to identify the nearby malicious devices while they want to continue to use mobile applications in public places. This dilemma makes protection of CSI-based attacks an urgent need. This article presents the first countermeasure for CSI-based attacks. Our key insight is that the success of any CSI-based attack requires high-quality CSI measurements; and we can significantly reduce the risk of information leakage by directing the user to a nearby location where the CSI readings are inherently noisy. To this end, we develop a regression based method to assess the risk of CSI-based attacks and exploit a well-established localization technique to identify potential malicious wireless devices. We then use this information to guide the user to a safe zone. We evaluate our approach by applying it to protect pattern lock and keystrokes in various indoor and outdoor environments. Experimental results show that our approach can effectively protect mobile users against CSI-based attacks