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.

The Impact of the Addition of Compatibilizers on Poly (lactic acid) (PLA) Properties after Extrusion Process.

Poly (lactic acid) (PLA), due to its biodegradability, biocompatibility, and renewability, is one of the most promising biobased polymers for replacing some of the petrol-based materials. Low flexibility of PLA is overcome, by blending it with olefin-based polymers, such as polypropylene (PP). However, the use of compatibilizing agents is required to attain final materials with suitable mechanical properties. Such agents, although essential, can affect PLA structure and, consequently, the mechanical properties of the PLA. To the best of our knowledge, this issue was never studied, and the results can contribute to achieving the best formulations of PLA-based blends according to their final applications. The thermal and mechanical properties of the extruded PLA, with three different commercial compatibilizing agents, were evaluated with the purpose of demonstrating how the compatibilizers can introduce structural differences into the PLA chain during the extrusion process. The combination of crystallinity, molecular weight, and the morphology of the samples after extrusion determines the final mechanical properties of PLA. Despite being a fundamental study, it is our aim to contribute to the sustainability of PLA-based industries. The addition of a 2.5% concentration of C1 compatibilizer seems to have less influence on the final morphology and mechanical properties of the blends.

A phase 2b multicenter, randomized, double-blind, placebo-controlled clinical trial to evaluate the efficacy and safety of vaginal rings containing nomegestrol acetate or etonogestrel and 17ß-estradiol in the treatment of women with primary dysmenorrhea.

OBJECTIVE: To evaluate the effect of investigational vaginal rings containing nomegestrol acetate (NOMAC) plus 17ß-estradiol (E2) or etonogestrel (ENG) plus E2 in women with moderate to severe primary dysmenorrhea. STUDY DESIGN: This was a Phase 2b randomized, placebo-controlled, multicenter, double-blind study. We randomized participants to one of five treatment groups: four hormonal rings and one placebo ring. The investigational vaginal rings released 300 µg of E2 daily along with 700 µg or 900 µg of NOMAC or 100 µg or 125 µg of ENG. Each participant received 2 identical rings and was to insert each for 21 days followed by a 7-day ring-free period. The primary endpoint, as assessed by a daily electronic diary (e-Diary), was the change in menstrual pain score from baseline to the second in-treatment withdrawal bleeding episode (Cycle 2). The pain score was the mean of the three highest scores for menstrual cramping pain (0-4 point scale) recorded from the day before menses to the third day of bleeding. The primary hypothesis was that at least one investigational vaginal ring would demonstrate a statistically significant larger reduction from baseline in pain score compared to placebo. Secondary endpoints included total mean impact score (which assessed the negative impact on work/school, physical activities, leisure/social activities) and the amount and days of rescue medication (ibuprofen) used. CLINICAL TRIAL REGISTRATION NUMBER: NCT01670656. RESULTS: We randomized 439 participants. The mean pain score decreased from baseline to Cycle 2 in all groups; the decrease in all four treatment groups compared to placebo was statistically significant (p-values ≤0.002). All treatment groups had greater reductions than placebo in ibuprofen intake and greater improvement in impact scores; these differences were statistically significant for both endpoints for the ENG-E2 100/300 µg/day group, while the other groups were not statistically significant for one or both endpoints. CONCLUSION: All four investigational rings produced a statistically significantly larger reduction from baseline in mean menstrual pain score compared to placebo while pain medication use decreased. IMPLICATIONS: This placebo-controlled study provides evidence that vaginal contraceptive rings containing NOMAC-E2 or ENG-E2 improve moderate to severe dysmenorrhea, across all of doses studied. This adds to the evidence that hormonal contraceptives are effective treatments for dysmenorrhea.

Phase II dose-finding study on ovulation inhibition and cycle control associated with the use of contraceptive vaginal rings containing 17ß-estradiol and the progestagens etonogestrel or nomegestrol acetate compared to NuvaRing.

PURPOSE: To identify at least one contraceptive vaginal ring that effectively inhibits ovulation and demonstrates cycle control that is non-inferior to NuvaRing® (Merck Sharp & Dohme B.V., The Netherlands) in terms of an unscheduled bleeding incidence, with a non-inferiority margin of 10%. METHODS: This was a randomised, active controlled, parallel group, multicentre, partially blinded trial in healthy women 18-35 years of age. Subjects received one of six contraceptive vaginal rings with an average daily release rate of 300 µg 17ß-estradiol (E2) and various rates of either etonogestrel (ENG; 75, 100, or 125 µg/day) or nomegestrol acetate (NOMAC; 500, 700, or 900 µg/day), or the active control NuvaRing® (ENG/ethinylestradiol 120/15 µg), for three 28-day cycles. RESULTS: Ovulation inhibition was observed in all groups as confirmed by absence of progesterone concentrations compatible with ovulation (>16 nmol/L) and absence of ultrasound evidence of ovulation. All investigational rings provided good cycle control, with the ENG-E2 125/300 µg/day group being associated with the best cycle control based on the numerically lowest incidence of unscheduled bleeding and absence of scheduled bleeding. Non-inferiority to NuvaRing® with respect to the incidence of unscheduled bleeding could not be concluded for any of the investigational ring groups. The safety profile was consistent with the known safety profile of combined estrogen/progestin contraceptives and similar across all groups. CONCLUSIONS: Contraceptive rings releasing 300 µg E2 and 75-125 µg/day of ENG or 500-900 µg/day of NOMAC provided adequate ovulation inhibition and cycle control and are generally well-tolerated. While non-inferiority to NuvaRing® was not met, among the investigational rings, the ENG-E2 125/300 ring provided the best cycle control.

Maxwell-Wagner Effect Applied to Microwave-Induced Self-Ignition: A Novel Approach for Carbon-Based Materials.

A new method for analytical applications based on the Maxwell-Wagner effect is proposed. Considering the interaction of carbonaceous materials with an electromagnetic field in the microwave frequency range, a very fast heating is observed due to interfacial polarization that results in localized microplasma formation. Such effect was evaluated in this work using a monomode microwave system, and temperature was recorded using an infrared camera. For analytical applications, a closed reactor under oxygen pressure was evaluated. The combination of high temperature and oxidant atmosphere resulted in a very effective self-ignition reaction of sample, allowing its use as sample preparation procedure for further elemental analysis. After optimization, a high sample mass (up to 600 mg of coal and graphite) was efficiently digested using only 4 mol L-1 HNO3 as absorbing solution. Several elements (Ba, Ca, Fe, K, Li, Mg, Na, and Zn) were determined by inductively coupled plasma optical emission spectrometry (ICP-OES). Accuracy was evaluated by using a certified reference material (NIST 1632b). Blanks were negligible, and only a diluted solution was required for analytes absorption preventing residue generation and making the proposed method in agreement with green chemistry recommendations. The feasibility of the proposed method for hard-to-digest materials, the minimization of reagent consumption, and the possibility of multi elemental analysis with lower blanks and better limits of detection can be considered as the main advantages of this method.

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.

Graphene: The Missing Piece for Cancer Diagnosis?

This paper reviews recent advances in graphene-based biosensors development in order to obtain smaller and more portable devices with better performance for earlier cancer detection. In fact, the potential of Graphene for sensitive detection and chemical/biological free-label applications results from its exceptional physicochemical properties such as high electrical and thermal conductivity, aspect-ratio, optical transparency and remarkable mechanical and chemical stability. Herein we start by providing a general overview of the types of graphene and its derivatives, briefly describing the synthesis procedure and main properties. It follows the reference to different routes to engineer the graphene surface for sensing applications with organic biomolecules and nanoparticles for the development of advanced biosensing platforms able to detect/quantify the characteristic cancer biomolecules in biological fluids or overexpressed on cancerous cells surface with elevated sensitivity, selectivity and stability. We then describe the application of graphene in optical imaging methods such as photoluminescence and Raman imaging, electrochemical sensors for enzymatic biosensing, DNA sensing, and immunosensing. The bioquantification of cancer biomarkers and cells is finally discussed, particularly electrochemical methods such as voltammetry and amperometry which are generally adopted transducing techniques for the development of graphene based sensors for biosensing due to their simplicity, high sensitivity and low-cost. To close, we discuss the major challenges that graphene based biosensors must overcome in order to reach the necessary standards for the early detection of cancer biomarkers by providing reliable information about the patient disease stage.

Spectroscopic investigation (FT-IR, FT-Raman and SERS), vibrational assignments, HOMO-LUMO analysis and molecular docking study of Opipramol.

FT-IR and FT-Raman spectra of Opipramol were recorded and analyzed. SERS spectrum was recorded in silver colloid. The vibrational wave numbers were computed using DFT quantum chemical calculations. The data obtained from wave number calculations are used to assign vibrational bands obtained in infrared and Raman spectra as well as in SERS of the studied molecule. Potential energy distribution was done using GAR2PED program. The geometrical parameters (DFT) of the title compound are in agreement with the XRD results. The presence of CH2 stretching modes in the SERS spectrum indicates the close of piperazine ring with the metal surface and the interaction of the silver surface with this moiety. NBO analysis, HOMO-LUMO, first hyperpolarizability and molecular electrostatic potential results are also reported. The inhibitor Opipramol forms a stable complex with P4502C9 as is evident from the ligand-receptor interactions and a -9.0 kcal/mol docking score and may be an effective P4502C9 inhibitor if further biological explorations are carried out.

Vibrational spectroscopic studies (FT-IR, FT-Raman, SERS) and quantum chemical calculations on cyclobenzaprinium salicylate.

FT-IR, FT-Raman and surface enhanced Raman scattering spectra of cyclobenzaprinium salicylate were recorded and analyzed. The vibrational wavenumbers were examined theoretically using the Gaussian09 set of quantum chemistry codes, and the normal modes were assigned by potential energy distribution calculations. The downshift of the OH stretching frequency is due to strong hydrogen bonded system present in the title compound as given by XRD results. The presence of CH3, CH2 and CO2 modes in the SERS spectrum indicates the nearness of the methyl group to the metal surface which affects the orientation and metal molecule interaction. The presence of phenyl ring modes in the SERS spectrum indicates a tilted orientation with respect to the metal surface. The geometrical parameters of the title compound are in agreement with XRD results. A computation of the first hyperpolarizability indicates that the compound may be a good candidate as a NLO material.

Vibrational spectroscopic (FT-IR, FT-Raman, SERS) and quantum chemical calculations of 3-(10,10-dimethyl-anthracen-9-ylidene)-N,N,N-trimethylpropanaminiium chloride (Melitracenium chloride).

FT-IR, FT-Raman spectra of Melitracenium chloride were recorded and analyzed. SERS spectrum was recorded in silver colloid. The vibrational wavenumbers were computed using DFT quantum chemical calculations. The data obtained from wavenumber calculations are used to assign vibrational bands obtained in infrared and Raman spectra as well as in SERS of the studied molecule. Potential energy distribution was done using GAR2PED program. The geometrical parameters (SDD) of the title compound are in agreement with the XRD results. The presence anthracene ring modes in the SERS spectrum suggest a tilted orientation with respect to the metal surface. The methyl groups in the title molecule are also close to the metal surface. The first hyperpolarizability, NBO analysis and molecular electrostatic potential results are also reported.

DNA-poly(vinyl alcohol) gel matrices: release properties are strongly dependent on electrolytes and cationic surfactants.

The release of DNA from cryogel PVA-DNA gel matrices to different electrolyte aqueous solutions was investigated. The rate of release and the distribution coefficient of DNA have been quantified by using a first order kinetic law equation, developed in the frame of a partition-based model. The release of DNA from gels to 1:1 sodium and nitrate salts shows that the transport properties are dependent on the ability of anions/cations to solubilise the DNA in the aqueous phase which, with the exception of bromide, can be related to the Hofmeister series; in the presence of multivalent electrolytes, or increasing the ionic strength, the condensation of DNA inside the gel, followed by a phase separation as seen by scanning electron microscopy, induces the retention of DNA inside the polymer matrix. The DNA condensation and/or phase separation, which contribute to a decrease in the water volume fraction inside the gel, determined by swelling degree experiments, also lead to a decrease in the rate constant of DNA release; such decrease can be justified by the difficulty of the molecular aggregate to move through out the polymeric structure. The DNA release is also dependent on the pH of the bulk solution. The effect of uni- and di-valent cationic surfactants on the release properties of DNA was also evaluated. Our findings suggest that the kinetics of DNA release depends on a complex balance between different structural properties of the surfactants, namely charge, bulkiness of the headgroup and alkyl chain length.

Graphene oxide versus functionalized carbon nanotubes as a reinforcing agent in a PMMA/HA bone cement.

Graphene oxide (GO) and functionalized carbon nanotubes (f-CNTs) (each in the concentration range of 0.01-1.00 wt/wt%) were investigated as the reinforcing agent in a poly(methyl methacrylate) (PMMA)/hydroxyapatite (HA) bone cement. Mixed results were obtained for the changes in the mechanical properties determined (storage modulus, bending strength, and elastic modulus) for the reinforced cement relative to the unreinforced counterpart; that is, some property changes were increased while others were decreased. We postulate that this outcome is a consequence of the fact that each of the nanofillers hampered the polymerization process in the cement; specifically, the nanofiller acts as a scavenger of the radicals produced during polymerization reaction due to the delocalized π-bonds. Results obtained from the chemical structure and polymer chain size distribution determined, respectively, by nuclear magnetic resonance and size exclusion chromatography analysis, on the polymer extracted from the specimens support the postulated mechanism. Furthermore, in the case of the 0.5 wt/wt% GO-reinforced cement, we showed that when the concentration of the radical species in the PMMA bone cement was doubled, mechanical properties markedly improved (relative to the value in the unreinforced cement), suggesting suppression of the aforementioned scavenger activity.

Aggregation and micellization of sodium dodecyl sulfate in the presence of Ce(III) at different temperatures: a conductometric study.

Aggregation properties of sodium dodecyl sulfate (SDS) in the presence of cerium(III) chloride, at various temperatures (298.15-323.15 K) have been measured by the electrical conductance technique. The experimental data on aqueous solutions as a function of SDS concentration show the presence of two inflexion points indicating the presence of two distinct interaction mechanisms: the first, occurring at SDS concentrations below the critical micelle concentration of the pure surfactant, which can be explained by the formation of aggregates between dodecyl sulfate (DS-) and Ce(III), while the second one, at SDS concentrations around the critical micelle concentration (cmc) of the pure surfactant which is due to the SDS micellization. The aggregation between DS- and Ce(III) was confirmed by static light scattering. The binding ratio of DS-/Ce(III) changes from 6 to 4, shows a slight dependence on the Ce(III) concentration and is independent of the temperature. The thermodynamic micellization parameters, Gibbs energy, enthalpy and entropy of micellization were calculated on the basis of the experimental data for the aggregation concentration, and the degree of counterion dissociation of the micelles. The SDS micellization is energetically favoured by increasing either the concentration of CeCl3 or the temperature. Such behaviour is clearly dominated by a decrease of the micellization (exothermic) enthalpy. The entropy of micellization approaches zero as the cerium(III) chloride concentration and temperature increase.