Anoxia Treatment for Delaying Skin Browning, Inhibiting Disease Development and Maintaining the Quality of Litchi Fruit

Litchi fruit has a very short shelf life after harvest, so marketers and consumers alike desire longer periods of storage, transportation and distribution. To extend shelf life, anoxia treatments were used for the fruit. Litchi fruit were exposed to pure N2 for 0, 3, 6, 12 or 24 h. They were then kept individually in closed but vented containers for 6 days in the dark at 20 °C and 95–100 % relative humidity. Exposure of litchi fruit to N2 for 3 or 6 h markedly delayed skin browning, reduced rot development and maintained higher concentrations of total soluble solids, titratable acidity and ascorbic acid after 6 days of storage. Anoxia treatment for 24 h reduced browning index, but it accelerated disease development, compared to the control. Thus, a pre-storage pure N2 treatment for 3 or 6 h can be an effective means of reducing rotting while maintaining the physical quality of the fruit

Effects of Pure Oxygen on the Rate of Skin Browning and Energy Status in Longan Fruit

Postharvest pericarp browning is one of the main problems resulting in reduced shelf life of longan fruit. Experiments were conducted to examine the changes in concentrations of adenosine triphosphate (ATP), adenosine diphosphate (ADP) and adenosine monophosphate (AMP), energy charge levels and activities of polyphenol oxidase (PPO) and peroxidase (POD) in relation to pericarp browning of longan fruit. Fruit kept for 6 days in pure oxygen atmosphere at 28 C showed lower browning indices and higher ATP concentrations but lower AMP concentrations and higher respiratory rates, compared to those kept in air. While energy charge decreased during storage, the decrease was delayed markedly by exposure to pure oxygen. There was a lower energy charge in the browned fruit, which was associated with rapid increase in malondialdehyde concentration. Enhanced respiration of longan fruit exposed to pure oxygen can result in the production of ATP. However, fruit exposed to pure oxygen exhibited higher activities of PPO and POD, which was not associated with reduced skin browning inhibition. These results supported the hypothesis that skin browning of postharvest longan fruit may be a consequence of membrane injury caused by the lack of maintenance energy

Slippery for scaling resistance in membrane distillation: a novel porous micropillared superhydrophobic surface

Scaling in membrane distillation (MD) is a key issue in desalination of concentrated saline water, where the interface property between the membrane and the feed become critical. In this paper, a slippery mechanism was explored as an innovative concept to understand the scaling behavior in membrane distillation for a soluble salt, NaCl. The investigation was based on a novel design of a superhydrophobic polyvinylidene fluoride (PVDF) membrane with micro-pillar arrays (MP-PVDF) using a micromolding phase separation (μPS) method. The membrane showed a contact angle of 166.0 ± 2.3° and the sliding angle of 15.8 ± 3.3°. After CF4 plasma treatment, the resultant membrane (CF4-MP-PVDF) showed a reduced sliding angle of 3.0o. In direct contact membrane distillation (DCMD), the CF4-MP-PVDF membrane illustrated excellent anti-scaling in concentrating saturated NaCl feed. Characterization of the used membranes showed that aggregation of NaCl crystals occurred on the control PVDF and MP-PVDF membranes, but not on the CF4-MP-PVDF membrane. To understand this phenomenon, a “slippery” theory was introduced and correlated the sliding angle to the slippery surface of CF4-MP-PVDF and its anti-scaling property. This work proposed a well-defined physical and theoretical platform for investigating scaling problems in membrane distillation and beyond

Unprecedented scaling/fouling resistance of omniphobic polyvinylidene fluoride membrane with silica nanoparticle coated micropillars in direct contact membrane distillation

Recent development of omniphobic membranes shows promise in scaling/fouling mitigation in membrane distillation (MD), however, the fundamental understanding is still under dispute. In this paper, we report a novel omniphobic micropillared membrane coated by silica nanoparticles (SiNPs) (SiNPs-MP-PVDF) with dual-scale roughness prepared by a micromolding phase separation (μPS) and electrostatic attraction. This membrane was used as a model for analysis of scaling behavior by calcium sulfate (CaSO4) scaling and fouling behavior by protein casein in comparison with commercial (C-PVDF) and micropillared (MP-PVDF) membranes. Unprecedented scaling/fouling resistance to CaSO4 and casein was observed in direct contact membrane distillation (DCMD) for SiNPs-MP-PVDF membrane. Similar scaling and fouling occurred for commercial PVDF and micropillared PVDF membranes. The observation corresponds well to the wetting state of all membranes as SiNPs-MP-PVDF shows suspended wetting, but MP-PVDF shows pinned wetting. From a hydrodynamic view, the suspended wetting attributes a slippery surface which reduces the direct contact of foulants to solid membrane part and leads to significantly reduced fouling and scaling. However, a pinned (or metastable) wetting state leads to a stagnant interfacial layer that is prone to severe fouling and scaling. This work highlights that both scaling and fouling resistance are indeed of suspended wetting state and slippage origin

Synthesis of pyridinium N-chloramines for antibacterial applications

To develop more efficacious antibacterial agents, a new type of cationic N-chloramines that contain a pyridinium moiety and a N-chloramine moiety covalently linked via an alkyl chain were prepared and characterized. Preliminary assays indicated that 1) the compound with a propylidene linker exhibited higher antibacterial activity than the quaternary ammonium counterpart; 2) the chain length of the alkyl linker had major effects on their biocidal properties. Our results may inspire exploration of more pyridinium N-chloramines for antibacterial applications. (C) 2016 Elsevier Ltd. All rights reserved

Rapamycin inhibits pathogen transmission in mosquitoes by promoting immune activation.

Repeated blood meals provide essential nutrients for mosquito egg development and routes for pathogen transmission. The target of rapamycin, the TOR pathway, is essential for vitellogenesis. However, its influence on pathogen transmission remains to be elucidated. Here, we show that rapamycin, an inhibitor of the TOR pathway, effectively suppresses Plasmodium berghei infection in Anopheles stephensi. An. stephensi injected with rapamycin or feeding on rapamycin-treated mice showed increased resistance to P. berghei infection. Exposing An. stephensi to a rapamycin-coated surface not only decreased the numbers of both oocysts and sporozoites but also impaired mosquito survival and fecundity. Transcriptome analysis revealed that the inhibitory effect of rapamycin on parasite infection was through the enhanced activation of immune responses, especially the NF-κB transcription factor REL2, a regulator of the immune pathway and complement system. Knockdown of REL2 in rapamycin-treated mosquitoes abrogated the induction of the complement-like proteins TEP1 and SPCLIP1 and abolished rapamycin-mediated refractoriness to Plasmodium infection. Together, these findings demonstrate a key role of the TOR pathway in regulating mosquito immune responses, thereby influencing vector competence

Synthesis of quaternary phosphonium N-chloramine biocides for antimicrobial applications

The recently developed quaternary ammonium (QA) N-chloramine has been proved to be a promising "composite" biocide with drastically boosted antibacterial efficacy afforded by the QA moiety. In this work, a series of quaternary phosphonium (QP) N-chloramine biocides, covalently combining an N-chloramine moiety and a QP moiety via varied aliphatic methylene units, were synthesized by means of multi-step chemical reactions. Preliminary antibacterial tests against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) showed that the synthetic QP N-chloramine exhibited distinctively higher biocidal efficacy than the QA counterpart. Furthermore, bactericidal tests also indicated that QP N-chloramine with a linker of -(CH2)(12)-showed the highest biocidal efficacy, suggesting synergistic action between the N-chloramine moiety and QP moiety