Electrospun Nanofibers Loaded with Plantago major L. Extract for Potential Use in Cutaneous Wound Healing.

Plantago major L. is a plant available worldwide that has been traditionally used for several medical applications due to its wound healing, anti-inflammatory, and antimicrobial properties. This work aimed to develop and evaluate a nanostructured PCL electrospun dressing with P. major extract encapsulated in nanofibers for applications in wound healing. The extract from leaves was obtained by extraction in a mixture of water:ethanol = 1:1. The freeze-dried extract presented a minimum inhibitory concentration (MIC) for Staphylococcus Aureus susceptible and resistant to methicillin of 5.3 mg/mL, a high antioxidant capacity, but a low content of total flavonoids. Electrospun mats without defects were successfully produced using two P. major extract concentrations based on the MIC value. The extract incorporation in PCL nanofibers was confirmed using FTIR and contact angle measurements. The PCL/P. major extract was evaluated using DSC and TGA demonstrating that the incorporation of the extract decreases the thermal stability of the mats as well as the degree of crystallinity of PCL-based fibers. The P. major extract incorporation on electrospun mats produced a significant swelling degree (more than 400%) and increased the capacity of adsorbing wound exudates and moisture, important characteristics for skin healing. The extract-controlled release evaluated using in vitro study in PBS (pH, 7.4) shows that the P. major extract delivery from the mats occurs in the first 24 h, demonstrating their potential capacity to be used in wound healing.

Exposure to Cry1 Toxins Increases Long Flight Tendency in Susceptible but Not in Cry1F-Resistant Female Spodoptera frugiperda (Lepidoptera: Noctuidae).

The fall armyworm (JE Smith) (Spodoptera frugiperda) is a polyphagous pest targeted by selected Cry and Vip3A insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) that are produced in transgenic Bt corn and cotton. Available evidence suggests that sublethal larval exposure to Cry1Ac increases flight activity in adult Spodoptera spp. However, it is not known whether this effect is also observed in survivors from generally lethal exposure to Cry1Ac. Moreover, while multiple cases of field-evolved resistance to Bt proteins have been described in the native range of S. frugiperda, the effect of resistance on flight behavior has not been examined. Long-distance migratory flight capacity of S. frugiperda is of concern given its ongoing global spread and the possibility that migrants may be carrying resistance alleles against pesticides and Bt crops. In this study, we used rotational flight mills to test the effects of generally lethal exposure to Cry1Ac in susceptible and sublethal exposure in Cry1F-resistant S. frugiperda strains. The results detected altered pupal weight after larval feeding on diet containing Cry proteins, which only translated in significantly increased tendency for longer flights in female moths from the susceptible strain. This information has relevant implications when considering current models and assumptions for resistance management of Bt crops.

Microwave-induced self-ignition: An efficient approach for high purity graphite digestion and multitechnique halogen determination.

In this work, high purity graphite, a high chemically stable material, was effectively digested using a single method allowing compatible solutions for the further multitechnique determination of halogens by: ion chromatography (F and Cl), inductively coupled plasma mass spectrometry (Cl, Br and I) and by ion selective electrode (only for F). The recent system using microwave-induced self-ignition (MISI) is based on the strong interaction between microwave radiation and graphite in a closed system pressurized with oxygen (Maxwell-Wagner effect). Carbon-based materials present intense and specific interfacial polarization when exposed to microwave electromagnetic field resulting in a fast heating rate. This effect associated to a pressurized oxygen system, provides a quick self-ignition of carbon-based materials and consequent combustion/digestion of organic matrices. Under optimized conditions, sample masses up to 600 mg were fully digested in a quartz vessel under 20 bar of oxygen pressure and using just a diluted solution (100 mmol L-1 NH4OH) for the quantitative absorption of all the analytes. MISI method was validated, and the accuracy (better than 94%) was evaluated by comparison of results obtained by pyrohydrolysis for two coal certified reference materials as well as with subsequent analytes determination by the three techniques: IC, ICP-MS and ISE. It is important to point out that no filter paper disks, electrical connections or other ignition aids are required as in the case of previous or classical combustion methods. Moreover, just a diluted absorbing solution was used resulting in negligible blanks and relatively low limits of detection. The digestion efficiency was higher than 99%, making the proposed method a suitable and powerful alternative for the quasi complete digestion of graphite and determination of halogens virtually free of interferences.

Feasibility of DS-GF AAS for the determination of metallic impurities in raw material for polymers production.

A new procedure is proposed for the determination of metal contaminants (Cr, Fe, Mg, Mn, Na and Ni) in polymeric diphenylmethane diisocyanate (PMDI), a raw material used to produce polyurethane polymers. The feasibility of using Zeeman-effect background correction graphite furnace atomic absorption spectrometry (GF AAS) and direct sampling (DS) was evaluated. Calibration using aqueous standard solutions was feasible and chemical modifiers as well as reference materials for this purpose were unnecessary. Relatively high sample masses (up to 23 mg) were used allowing very low limits of detection ranging from 0.06 ng g-1 to 1 ng g-1 (Fe and Mg) up to 3  ng g-1 (Ni), with relative standard deviation lower than 15%. The following parameters were evaluated: pyrolysis and atomization temperatures , sample mass, as well as the use of low sensitivity conditions (Zeeman effect background correction magnetic field strength adjustment and the use of a secondary wavelength for Fe and Na determinations, respectively). Results were compared with those obtained by microwave-assisted digestion and microwave-induced combustion with subsequent analytes determination by inductively coupled plasma optical emission spectrometry (ICP-OES) and by inductively coupled plasma mass spectrometry (ICP-MS). No significant difference was observed between the results obtained by DS-GF AAS, ICP-MS and ICP-OES after both digestion systems. The proposed DS-GF AAS method allowed the determination of six elements in PMDI (which is considered as a complex matrix) with limits of detection lower than those achieved by other methods. This new procedure can be used as quality control of polyurethanes industry for ultra-trace inorganic impurities.

New possibilities for pharmaceutical excipients analysis: Combustion combined with pyrohydrolysis system for further total chlorine determination by ICP-OES.

An alternative method for the determination of total chlorine content in hydroxypropyl cellulose (HPC) was applied, combining a recently developed system based on a combustion step followed by pyrohydrolysis reaction. Using this approach it the determination of total chlorine by inductively coupled plasma optical emission spectrometry (ICP-OES) without interferences was feasible. It overcame the limitations of European Pharmacopoeia (EP) method for HPC analysis regarding to the inability to determine total chlorine in HPC, once some chlorine compounds (e.g., chloroform) that can not be identified by the official method (EP). The following parameters of combustion and pyrohydrolysis were evaluated: absorbing solution, sample mass, the use of powdered silica as retardant of combustion, oxygen flow rate and reaction time. Reference values for total chlorine were obtained after digestion using microwave-induced combustion and determination by ion chromatography (IC). Microwave-assisted extraction (MAE) was also investigated for Cl extraction. The accuracy of the proposed method was also evaluated by analyte recovery tests (agreement of 95-103%), as well as by the analysis of certified reference materials (CRMs). The agreement with the certified values was higher than 95% and the limit of quantification (LOQ) was 50 µg g-1. Up to 500 mg of sample were efficiently digested by the proposed method in 5 min (dissolved carbon in digests was below 50 mg L-1). Total chlorine content in samples of modified cellulose ranged from 284 to 576 µg g-1. Despite the relatively high chlorine content in all samples, the concentration was lower than the maximum limit allowed by the EP for HPC (0.5%).

Simultaneous determination of iron and nickel in fluoropolymers by solid sampling high-resolution continuum source graphite furnace atomic absorption spectrometry.

This paper reports the development of a method of simultaneous determination of iron and nickel in fluoropolymers by high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS) with direct solid sampling. In order to carry out simultaneous measurements, both the main resonance line of nickel (232.003nm) and the adjacent secondary line of iron (232.036nm) were monitored in the same spectral window. The proposed method was optimized with a perfluoroalkoxy (PFA) sample and was applied to the determination of iron and nickel in fluorinated ethylene propylene (FEP) and modified polytetrafluoroethylene (PTFE-TFM) samples. Pyrolysis and atomization temperatures, as well as the use of Pd and H2 (during pyrolysis) as chemical modifiers, were carefully investigated. Compromise temperatures for pyrolysis and atomization of both analytes were achieved at 800 and 2300°C, respectively, using only 0.5Lmin(-1) H2 as chemical modifier during pyrolysis. Calibration curves were performed with aqueous standards by using a single solution which contained both analytes. Limits of detection were 221 and 9.6ngg(-1) for iron and nickel, respectively. Analyte concentrations in all samples ranged from 3.53 to 12.4µgg(-1) for iron and from 37 to 78ngg(-1) for nickel, with relative standard deviation less than 19%. Accuracy was evaluated by comparing these results with those obtained by inductively coupled plasma mass spectrometry after sample digestion by microwave-induced combustion and no significant statistical difference was observed.

Determination of halogens and sulfur in high-purity polyimide by IC after digestion by MIC.

In this work, a method for sample preparation of high-purity polyimide was proposed for halogens and sulfur determination by ion chromatography (IC) with conductivity detection and, alternatively, by inductively coupled plasma mass spectrometry (ICP-MS). A relatively high polyimide mass (600mg) was completely digested by microwave-induced combustion (MIC) using 20bar of O2 and 50mmolL(-1) NH4OH as absorbing solution. These conditions allowed final solutions with low carbon content (<10mgL(-1)) and suitable pH for analysis by both IC and ICP-MS. The accuracy was evaluated using a certified reference material of polymer for Cl, Br and S and spike recovery experiments for all analytes. No statistical difference (t-test, 95% of confidence level) was observed between the results obtained for Cl, Br and S by IC after MIC and the certified values. In addition, spike recoveries obtained for F, Cl, Br, I and S ranged from 94% to 101%. The proposed method was suitable for polyimide decomposition for further determination of halogens and sulfur by IC and by ICP-MS (Br and I only). Taking into account the lack of methods and the difficulty of bringing this material into solution, MIC can be considered as a suitable alternative for the decomposition of polyimide for routine quality control of halogens and sulfur using IC or ICP-MS.

Development of a New Container for Storage and Release of the Parasitoid Cotesia flavipes (Hymenoptera: Braconidae).

In Brazil, the parasitoid Cotesia flavipes (Cameron) has been used as a biological control agent against Diatraea saccharalis (F.) since 1976, because of its effectiveness in reducing populations of this pest. Three million plastic cups are used annually to release C. flavipes, which remain in the environment. This study aimed to develop fully biodegradable packaging, so that releases occur without damaging the environment. The biological characteristics of C. flavipes were studied for five generations in the packaging developed (biodegradable boxes) and in the packaging currently used (non-biodegradable plastic cups and biodegradable cups), as were the costs. The results demonstrated the feasibility of using completely biodegradable and inexpensive packaging for the rearing, transport, and release of adult C. flavipes in the field.

Blood coagulation dynamics: mathematical modeling and stability results.

The hemostatic system is a highly complex multicomponent biosystem that under normal physiologic conditions maintains the fluidity of blood. Coagulation is initiated in response to endothelial surface vascular injury or certain biochemical stimuli, by the exposure of plasma to Tissue Factor (TF), that activates platelets and the coagulation cascade, inducing clot formation, growth and lysis. In recent years considerable advances have contributed to understand this highly complex process and some mathematical and numerical models have been developed. However, mathematical models that are both rigorous and comprehensive in terms of meaningful experimental data, are not available yet. In this paper a mathematical model of coagulation and fibrinolysis in flowing blood that integrates biochemical, physiologic and rheological factors, is revisited. Three-dimensional numerical simulations are performed in an idealized stenosed blood vessel where clot formation and growth are initialized through appropriate boundary conditions on a prescribed region of the vessel wall. Stability results are obtained for a simplified version of the clot model in quiescent plasma, involving some of the most relevant enzymatic reactions that follow Michaelis-Menten kinetics, and having a continuum of equilibria.