A MIP-CP based approach for two- and three-dimensional cutting problems with staged guillotine cuts

This work presents guillotine constraints for two- and three-dimensional cutting problems. These problems look for a subset of rectangular items of maximum value that can be cut from a single rectangular container. Guillotine constraints seek to ensure that items are arranged in such a way that cuts from one edge of the container to the opposite edge completely separate them. In particular, we consider the possibility of 2, 3, and 4 cutting stages in a predefined sequence. These constraints are considered within a two-level iterative approach that combines the resolution of integer linear programming and constraint programming models. Experiments with instances of the literature are carried out, and the results show that the proposed approach can solve in less than 500 s approximately 60% and 50% of the instances for the two- and three-dimensional cases, respectively. For the two-dimensional case, in comparison with the recent literature, it was possible to improve the upper bound for 16% of the instances.

     

Negative Ion MALDI Mass Spectrometry of Polyoxometalates (POMs): Mechanism of Singly Charged Anion Formation and Chemical Properties Evaluation

MALDI-MS has been developed for the negative ion mode analysis of polyoxometalates (POMs). Matrix optimization was performed using a variety of matrix compounds. A first group of matrixes offers MALDI mass spectra containing abundant intact singly charged anionic adduct ions, as well as abundant in-source fragmentations at elevated laser powers. A relative ranking of the ability to induce POM fragmentation is found to be: DAN > CHCA > CNA > DIT> HABA > DCTB > IAA. Matrixes of a second group provide poorer quality MALDI mass spectra without observable fragments. Sample preparation, including the testing of salt additives, was performed to optimize signals for a model POM, POMc12, the core structure of which bears four negative charges. The matrix 9-cyanoanthracene (CNA) provided the best signals corresponding to singly charged intact POMc12 anions. Decompositions of these intact anionic species were examined in detail, and it was concluded that hydrogen radical-induced mechanisms were not prevalent, but rather that the observed prompt fragments originate from transferred energy derived from initial electronic excitation of the CNA matrix. Moreover, in obtained MALDI mass spectra, clear evidence of electron transfer to analyte POM species was found: a manifestation of the POMs ability to readily capture electrons. The affinity of polyanionic POMc12 toward a variety of cations was evaluated and the following affinity ranking was established: Fe³⁺ > Al³⁺ > Li⁺ > Ga³⁺ > Co²⁺ > Cr³⁺ > Cu²⁺ > [Mn²⁺, Mg²⁺] > [Na⁺, K⁺]. Thus, from the available cationic species, specific adducts are preferentially formed, and evidence is given that these higher affinity POM complexes are formed in the gas phase during the early stages of plume expansion.

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Graphical Abstract ?

     

Easing the concept “Balanced Approach” to airports with densely busy surroundings – The case of Congonhas Airport

This paper presents the difficulties found in trying to apply the “Balanced Approach” concept of ICAO (UN-International Civil Aviation Organization) on the noise pollution mitigation at urban Brazilian airports using, as a case study, the Congonhas Airport. It has been discussed by means of alternative operating scenarios, how to make the concept more flexible, aiming to bring the benefit of any additional acoustic comfort, without diminishing the installed capacity and already limited for environmental reasons. The results show that there are conditions for improvement, since there are both awareness of all players involved and permanent and real-time noise monitoring, even if those mitigating measures are not reflected on the noise annoyance models currently adopted for the land use planning.     

Direct detection of particles formed by laser ablation of matrices during matrix-assisted laser desorption/ionization

We report the detection of nanoparticles formed by irradiating matrix-assisted laser desorption/ionization (MALDI) matrix samples. This is direct evidence for the ejection of large size aggregates in the MALDI process. Nanometer-size particles were generated via a tunable solid-state UV laser, irradiating a sample placed in a nitrogen atmosphere. Size distribution measurements were performed using a differential mobility analyzer and a condensation particle counter. Particles in the 10-1000 nm size range were detected. The dependence of the particle size distribution on the laser fluence, wavelength and matrix was investigated. The observed effects are discussed and related to the MALDI ablation dynamics and gas-phase processes.     

Synthesis of (arylselanyl)- and (arylsulfenyl)-alkyl-1,2,3-triazolo-1,3,6-triazonines via a copper-catalyzed multicomponent reaction

An efficient copper-catalyzed multicomponent reaction was developed for the synthesis of (arylselanyl)- or (arylsulfenyl)-alkyl-1,2,3-triazolo-1,3,6-triazonines. The products were obtained in moderate to excellent yields via the reaction of o-phenylenediamine, 2-azidobenzaldehyde and different arylchalcogenyl alkynes using catalytic copper iodide in 1,4-dioxane at 100?°C. The reactions tolerated a range of substituents on the arylchalcogenyl alkynes and proved to be an efficient methodology for the combinatorial synthesis of new selenium or sulfur-containing triazonine derivatives.     

A new isoflavone glycoside from Ceiba pentandra (L.) Gaertner

From the 80% EtOH extract of the bark of Ceiba pentandra (L.) Gaertner, a new isoflavone glycoside was isolated along with known isoflavones, vavain and vavain glucoside. The structure was elucidated by spectroscopic analysis as 5-hydroxy-7,4',5'-trimethoxyisoflavone 3'-O-alpha-L-arabinofuranosyl(1-->6)-beta-D-glucopyranoside.     

Stereoselective preparation of conjugated E-enynes from E-vinylic tellurides and terminal alkynes via Sonogashira cross-coupling

E-Vinylic tellurides undergo a direct cross-coupling reaction with terminal alkynes in the presence of palladium(II)/CuI in Et(3)N at room temperature to give E-enynes in good yields. The methodology represents a general and efficient protocol for carrying out the synthesis of E-enynes under mild conditions with complete retention of configuration.     

Analysis of methylglyoxal in water and biological matrices by capillary zone electrophoresis with diode array detection

We describe a new method for the determination of methylglyoxal in water and biological matrices, using o-phenylenediamine as derivatizing agent and solid-phase extraction followed by capillary zone electrophoresis with diode array detection. 25 mM sodium phosphate running buffers at pH 2.2, 30 kV, and 25 degrees C allowed the best instrumental conditions for the optimum separation of methylglyoxal in a suitable analytical time (< 10 min), using an uncoated fused-silica capillary of 75 microm inner diameter and an effective length of 45.1 cm with an extended light path and the wavelength set to 200 nm. Under optimized instrumental conditions, good reproducibility of the migration time (< 1.1%), precision (< 5%), an excellent linear dynamic range from 0.1 to 3.6 mg/L (r(2) = 0.9997), and low limits of detection (7.2 microg/L) were obtained for methylglyoxal measurements, using the internal standard methodology. Assays on laboratory-spiked tap and ground water samples allowed a remarkable accuracy, presenting yields of 95.0 +/- 4.3 and 94.0 +/- 1.1%, respectively, and good performance to determine methylglyoxal in beer and yeast cells suspensions matrices was also obtained at trace level. The present methodology is a cost-effective alternative for routine quality control analysis, showing to be reliable, sensitive, and with a low sample volume requirement to monitor methylglyoxal in water and biological matrices.     

Synthesis and characterization of hybrids derived from vermiculite chloropropyl and aliphatic diamines

Silylation of vermiculite surface with organosilane (H₃CO)₃SiR, being R is the corresponding organic moieties –CH₂CH₂CH₂Cl, were carried out to yield organofunctionalized nanomaterial, named as VCl. The product reacted subsequently with three aliphatic diamines H₂N (CH₂)_nNH₂ (n=2, 4 and 6). The new hybrids were characterized by elemental analysis, infrared spectroscopy, X-ray diffraction and thermogravimetry. The grafting chloro derivates onto surface amounted to 2.1 mmol g^–1. The incorporation of alkyl amines was more effective for butyl>ethylene>hexyldiamines. The sequence is in agreement with thermogravimetry and elemental analysis data.