Rheological and anti-microbial study of silica and silver nanoparticles-reinforced k-carrageenan/hydroxyethyl cellulose composites for food packaging applications

Cellulose - Sustainable food packaging films were developed using a combination of k-Carrageenan (k-C), hydroxyl ethyl cellulose (HEC), silicon dioxide (SiO2), and silver (Ag) nanoparticles. The...     

Dramatic Influence of an Anionic Donor on the Oxygen‐Atom Transfer Reactivity of a MnV–Oxo Complex

Addition of an anionic donor to an Mn^V(O) porphyrinoid complex causes a dramatic increase in 2‐electron oxygen‐atom‐transfer (OAT) chemistry. The 6‐coordinate [Mn^V(O)(TBP₈Cz)(CN)]^? was generated from addition of Bu₄N⁺CN^? to the 5‐coordinate Mn^V(O) precursor. The cyanide‐ligated complex was characterized for the first time by Mn K‐edge X‐ray absorption spectroscopy (XAS) and gives Mn?O=1.53 Å, Mn?CN=2.21 Å. In combination with computational studies these distances were shown to correlate with a singlet ground state. Reaction of the CN^? complex with thioethers results in OAT to give the corresponding sulfoxide and a 2e^?‐reduced Mn^III(CN)^? complex. Kinetic measurements reveal a dramatic rate enhancement for OAT of approximately 24 000‐fold versus the same reaction for the parent 5‐coordinate complex. An Eyring analysis gives ΔH^≠=14 kcal mol^?1, ΔS^≠=?10 cal mol^?1 K^?1. Computational studies fully support the structures, spin states, and relative reactivity of the 5‐ and 6‐coordinate Mn^V(O) complexes.     

Water disinfection activity of cellulose filters treated with polycarboxylic acid and aromatic amine

A cellulose filter for water disinfection was developed using a polycarboxylic acid and an aromatic amine via a simple process with water as a solvent. 1,2,3,4-Butanetetracarboxylic acid/m-phenylenediamine solution was applied to cellulose filters using a pad–dry–curing process. The surfaces of treated cellulose filters were examined by Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy. The liquid permeabilities of treated cellulose filters were determined by capillary flow porometry, and their water disinfection efficacies were measured by non-pressure-driven filtration. Chlorinated cellulose filters disinfected Escherichia coli- and Staphylococcus aureus-containing solutions to a much higher degree than observed for nonchlorinated cellulose filters.     

Total Synthesis of (±)‐Phyllantidine: Development and Mechanistic Evaluation of a Ring Expansion for Installation of Embedded Nitrogen‐Oxygen Bonds

The development of a concise total synthesis of (±)‐phyllantidine ( 1 ), a member of the securinega family of alkaloids containing an unusual oxazabicyclo[3.3.1]nonane core, is described. The synthesis employs a unique synthetic strategy featuring the ring expansion of a substituted cyclopentanone to a cyclic hydroxamic acid as a key step that allows facile installation of the embedded nitrogen‐oxygen (N?O) bond. The optimization of this sequence to effect the desired regiochemical outcome and its mechanistic underpinnings were assessed both computationally and experimentally. This synthetic approach also features an early‐stage diastereoselective aldol reaction to assemble the substituted cyclopentanone, a mild reduction of an amide intermediate without N?O bond cleavage, and the rapid assembly of the butenolide found in ( 1 ) via use of the Bestmann ylide.     

Anti-Inflammatory Activities of the Ethanol Extract of Prasiola japonica,an Edible Freshwater Green Algae,and Its Various Solvent Fractions in LPS-Induced Macrophages and Carrageenan-Induced Paw Edema via the AP-1 Pathway

Prasiola japonica possesses several biological activities. However, reports on the anti-inflammatory activities and molecular mechanisms of its different solvent fractions remain limited. In this study, we investigated the potential anti-inflammatory activities of P. japonica ethanol extract (Pj-EE) and four solvent fractions of Pj-EE made with hexane (Pj-EE-HF), chloroform (Pj-EE-CF), butanol (Pj-EE-BF), or water (Pj-EE-WF) in both in vitro (LPS-induced macrophage-like RAW264.7 cells) and in vivo (carrageenan-induced acute paw edema mouse models) experiments. The most active solvent fraction was selected for further analysis. Various in vitro and in vivo assessments, including nitric oxide (NO), cytokines, luciferase assays, real-time polymerase chain reactions, and immunoblotting analyses were performed to evaluate the underlying mechanisms. In addition, the phytochemical constituents were characterized by Liquid chromatography-tandem mass spectrometry. In in vitro studies, the highest inhibition of NO production was observed in Pj-EE-CF. Further examination revealed that Pj-EE-CF decreased the expression of inflammation-related cytokines in LPS-induced RAW264.7 cells and suppressed subsequent AP-1-luciferase activity by inhibition of phosphorylation events in the AP-1 signaling pathway. Pj-EE-CF treatment also demonstrated the strongest reduction in thickness and volume of carrageenan-induced paw edema, while Pj-EE-BF showed the lowest activity. Furthermore, Pj-EE-CF also reduced gene expression and cytokines production in tissue lysates of carrageenan-induced paw edema. These findings support and validate the evidence that Pj-EE, and especially Pj-EE-CF, could be a good natural source for an anti-inflammatory agent that targets the AP1 pathway.     

Networks of rigid molecules

Networks of rigid molecules do not fit into the paradigm of classical theories of rubber elasticity. Some experimental properties of rigid polyamide networks are summarised, and the basis for a theoretical understanding of such systems is discussed and elaborated in terms of the properties such as the existence of several conformational states and twist of such network elements.     

Towards Designing a Trusted Routing Solution in Mobile Ad Hoc Networks

Designing a trusted and secure routing solution in an untrustworthy scenario is always a challenging problem. Lack of physical security and low trust levels among nodes in an ad hoc network demands a secure end-to-end route free of any malicious entity. This is particularly challenging when malicious nodes collude with one another to disrupt the network operation. In this paper we have designed a secure routing solution to find an end-to-end route free of malicious nodes with collaborative effort from the neighbors. We have also extended the solution to secure the network against colluding malicious nodes, which, to the best of our knowledge, is the first such solution proposed. We have also proposed a framework for computing and distributing trusts that can be used with out trusted routing protocol. Our proposed framework is unique and different from the other schemes in that it tries to analyze the psychology of the attacker and quantifies the behavior in the computational model. Extensive simulation has been carried out to evaluate the design of our protocol. Partially funded by Department of Defense Award No. H98230-04-C-0460, Department of Transportation Project No. FL-26-7102-00 and National Science Foundation Grant Nos. ANI-0123950 and CCR-0196557. Tirthankar Ghosh is a PhD candidate in the Telecommunications and Information Technology Institute at Florida International University. His area of research is routing security and trust computation in wireless ad hoc and sensor networks. He received his Bachelor of Electrical Engineering from Jadavpur University, India and Masters in Computer Engineering from Florida International University. Dr. Niki Pissinou received her Ph.D. in Computer Science from the University of Southern California, her M.S. in Computer Science from the University of California at Riverside, and her B.S.I.S.E. in Industrial and Systems Engineering from The Ohio State University. She is currently a tenured professor and the director of the Telecommunication & Information Technology Institute at FIU. Previously Dr. Pissinou was a tenured faculty at the Center for Advanced Computer Studies at the University of Louisiana at Lafayette where she was also the director of the Telecommunication & Information & Technology Laboratory partially funded by NASA, and the co-director of the NOMAD: A Wireless and Nomadic Laboratory partially funded by NSF, and the Advanced Network Laboratory. Dr. Pissinou is active in the fields computer networks, information technology and distributed systems. Dr. Kami (Sam) Makki has earned his Ph.D. in Computer Science from the University of Queensland in Brisbane Australia, his Masters degree in Computer Science and Engineering from the University of New South Wales in Sydney Australia, and his Bachelor and Masters Degrees in Civil Engineering from the University of Tehran Iran. Before joining the department of Electrical Engineering and Computer Science at the University of Toledo he has held a number of academic positions and research appointments at the Queensland University of Technology in Brisbane, Royal Melbourne Institution of Technology in Melbourne and at The University of Queensland in Brisbane Australia. He is an active researcher in the fields of distributed systems, databases, mobile and wireless communications, and has more than 30 publications in peerreviewed journals and international proceedings. He has served as a chair and technical program committee member and reviewer for a number of IEEE and ACM sponsored technical conferences and has received a number of achievement awards.     

A study on radial directional natural frequency and damping ratio in a vehicle tire

The measurement of radial directional natural frequency and damping ratio in a vehicle tire has been studied. Natural frequencies and damping ratios in the radial direction of various tires, from passenger car tires to truck bus tires, are reported. The radial direction modal parameters of tires subjected to different levels of inflation pressure, have been determined by using a frequency response function method. To obtain the theoretical natural frequency and mode shape, the plane vibration of a tire has been modeled as though it were that of a circular beam. By using the Tielking method that is based on Hamilton’s principle, theoretical results have been determined by considering the rotational velocity, tangential and radial stiffness, radial directional velocity and tension force which is due to tire inflation pressure. The results show that experimental conditions can be considered as the parameters that shift the natural frequency and damping ratio.