Very efficient epoxidation of 1,4‐polybutadiene with the biphasic system methyltrioxorhenium (MTO)‐CH2Cl2/H2O2

The biphasic system methyltrioxorhenium (MTO)‐H₂O₂/CH₂Cl₂ was studied in the epoxidation of polybutadiene and the results showed that this system presents a high selectivity and the extension of epoxidation (10–50%) can be modulated by the amount of oxidant added, without significant change in the molecular weight of the polymer.     

Determination of volatile organic compounds in recycled polyethylene terephthalate and high-density polyethylene by headspace solid phase microextraction gas chromatography mass spectrometry to evaluate the efficiency of recycling processes

A method for the determination of volatile organic compounds (VOCs) in recycled polyethylene terephthalate and high-density polyethylene using headspace sampling by solid-phase microextraction and gas chromatography coupled to mass spectrometry detection is presented. This method was used to evaluate the efficiency of cleaning processes for VOC removal from recycled PET. In addition, the method was also employed to evaluate the level of VOC contamination in multilayer packaging material containing recycled HDPE material. The optimisation of the extraction procedure for volatile compounds was performed and the best extraction conditions were found using a 75 μm carboxen-polydimethylsiloxane (CAR-PDMS) fibre for 20 min at 60 °C. The validation parameters for the established method were linear range, linearity, sensitivity, precision (repeatability), accuracy (recovery) and detection and quantification limits. The results indicated that the method could easily be used in quality control for the production of recycled PET and HDPE.     

Physics in organizations: A percolating approach

A percolation-based model to describe organizational structures is proposed, and its main characteristics are delineated. The model is applied in the study of a frequent organizational drawback faced by managers, directors, etc.: the 'leadership hindrance'. It is demonstrated that this and other organizational problems are circumvented by the reshaping of the enterprise 'susceptibility profile', conducted by actions of the leader and his/her staff. The interplay between short- and long-range interactions within the organizational structure as the determinants of extensivity and non-extensivity is discussed. The potentialities of the percolation model for a broader range of organizational applications are addressed.     

Chiral Schwinger model with a Podolsky term at finite temperature

We study an exactly solvable two-dimensional model which mimics the basic features of the standard model. This model combines chiral coupling with an infrared behavior which resembles low energy QCD. This is done by adding a Podolsky higher-order derivative term in the gauge field to the Lagrangian of the usual chiral Schwinger model. We adopt a finite temperature regularization procedure in order to calculate the non-trivial fermionic Jacobian and obtain the photon and fermion propagators, first at zero temperature and then at finite temperature in the imaginary and real time formalisms. Both singular and non-singular cases, corresponding to the choice of the regularization parameter, are treated. In the nonsingular case there is a tachyonic mode as usual in a higher order derivative theory, however in the singular case there is no tachyonic excitation in the spectrum.     

The preparation and reactions of protected glyphosate imidate,thioimidate, and thiono esters from N-[diphenoxyphosphinylmethyl]glycinonitrile: Comparative reactivities of activated carboxylate versus phosphonate esters

The highly efficient syntheses of novel protected glyphosate imidate, thioimidate, and thiono ester derivatives are described starting from N-[diphenoxyphosphinylmethyl]glycinonitrile 3b . The scope, utility and limitations in using each of these activated carboxylate functionalities for further transformations to new “masked” heterocyclic derivatives are defined. While the solution stability of the imidate and thioimidate series limited the synthetic application of these species, the corresponding thiono ester derivatives were valuable synthetic intermediates, providing a short, efficient route to the first glyphosate derivatives containing 1,3,4-oxadiazole and 1,2,4-triazole ring systems in place of the carboxylate group. These thiono esters thus undergo selective nucleophilic addition at this activated carboxylate center, while retaining the reactive diphenyl phosphonate moiety.     

Seasonal Chemical Evaluation of Miconia chamissois Naudin from Brazilian Savanna

Miconia chamissois Naudin is a species from the Cerrado, which is being increasingly researched for its therapeutic potential. The aim of this study was to obtain a standardized extract and to evaluate seasonal chemical variations. Seven batches of aqueous extracts from leaves were produced for the standardization. These extracts were evaluated for total solids, polyphenol (TPC) and flavonoid content (TFC), vitexin derivative content, antioxidant activity; thin-layer chromatography (TLC), and high-performance liquid chromatography (HPLC) profiles were generated. For the seasonal study, leaves were collected from five different periods (May 2017 to August 2018). The results were correlated with meteorological data (global radiation, temperature, and rainfall index). Using chromatographic and spectroscopic techniques, apigenin C-glycosides (vitexin/isovitexin) and derivatives, luteolin C-glycosides (orientin/isoorientin) and derivatives, a quercetin glycoside, miconioside B, matteucinol-7-O-β-apiofuranosyl (1 → 6) -β-glucopyranoside, and farrerol were identified. Quality parameters, including chemical marker quantification by HPLC, and biological activity, are described. In the extract standardization process, all the evaluated parameters showed low variability. The seasonality study revealed no significant correlations (p < 0.05) between TPC or TFC content and meteorological data. These results showed that it is possible to obtain extracts from M. chamissois at any time of the year without significant differences in composition.     

Preparation of Polymer Microparticles through Nonaqueous Suspension Polycondensations: Part V—Modeling and Parameter Estimation for Poly(butylene succinate) Polycondensations

Polycondensation polymers are normally produced through bulk and solution polymerization processes, which are characterized by significant mass and heat transfer constraints and difficult polymer purification (when prepared in solution). Therefore, it is desirable to develop industrial processes that can circumvent some of these limitations. Recently, a suspension polycondensation process has been developed, rendering the industrial process simpler and enabling the manufacture of polycondensation polymer microparticles. For this reason, the present work builds a phenomenological model to describe the analyzed suspension polycondensation reactions and estimate the model parameters required to simulate poly(butylene succinate) suspension polycondensations. It is shown that both the suspending medium and the reaction conditions can affect the mass transfer resistance for removal of water and that mass transfer rate coefficients are controlled mainly by reaction temperature and solubility of water in the suspending medium, leading to higher mass transfer rates when polymerizations are carried out in soybean oil (when compared to paraffin) at higher temperatures.     

DNA quantitation and degradation assessment: a quantitative PCR protocol designed for small forensic genetics laboratories

For over 10 years, quantitative PCR (qPCR) for DNA quantitation has been reported in forensics. However, assays have not been described for small qPCR platforms. Thus, technological advancement is not always implemented in small forensic genetics laboratories. A duplex qPCR assay is reported, using a StepOne instrument and targeting a short and a long human DNA region. This study was performed according to international validation guidelines, including sensitivity, repeatability, reproducibility, precision, accuracy, contamination assessment, known and case-type samples, and degradation studies. Characterization of the genetic markers, species specificity, and population studies had already been conducted. Moreover, case-type samples were quantified, amplified using commercial kits and the number of alleles detected was recorded. Sensitivity was shown to be 10 pg/µL. Standard curve replicates demonstrated the assay is accurate, precise, as well as fairly repeatable and reproducible. The NGM Detect kit was shown to yield higher peaks than Identifiler Plus and NGM Select for degraded samples. Moreover, quality sensors were always present and proved useful. The quantification values of the large target showed a correlation with the number of alleles detected in the STR profiles for known and casework samples. The degradation index was shown to be informative, with a value of 10 or higher indicating dropout. It is suggested that after quantitation, samples with low or degraded DNA be amplified using newer amplification kits containing quality sensors to confirm that the low-quality profile was not affected by inhibition.     

Use of bacterial cellulose in the textile industry and the wettability challenge—a review

Bacterial cellulose (BC) has been studied as an alternative material in several segments of the food, pharmaceutical, materials and textile industries. The importance of BC is linked to sustainability goals, since it is an easily degradable biomaterial of low toxicity to the environment and is a renewable raw material. For use in the textile area, bacterial cellulose has attracted great interest from researchers, but it presents some challenges notably to its hydrophilic structure. This integrative review article brings together studies and methods related to minimizing the hydrophilicity of bacterial cellulose, in order to expand its applicability in the textile industry in its dry state. The databases consulted were Scopus, ScienceDirect, ProQuest and Web of Science, the documents investigated were scientific articles and the time period investigated was between 2015 and 2021. The results showed that although there are methods to make the BC membrane more hydrophobic, future studies in this regard and on other properties must continue so that bacterial cellulose can be commercially introduced in the textile sector.

     

Synthesis of Ce0.8Sm0.2O1.9 solid electrolyte by a proteic sol‐gel green method

The present study reports the synthesis of Ce_0.8Sm_0.2O_1.9 solid electrolyte by a novel proteic sol‐gel method which uses gelatin as polymerizing agent. The as‐synthesized powder material was calcined at 700 °C for 2 h, with X‐ray diffraction revealing a single cubic phase with lattice parameter a = 0.5435 nm and theoretical density of 7.144 gcm^‐3. The average crystallite size is 12 nm, as determined by the Scherrer equation. Impedance spectroscopy revealed a larger resistive contribution of the grain boundaries than that from grain bulk, which, due to its lower activation energy, tends to dominate the total conductivity above 650 °C. The total conductivity is in line with literature data for ceramics of the same composition prepared by various methods, thus confirming the potential of the proteic sol‐gel method as a green, low cost alternative synthetic route to prepare ceria‐based solid electrolytes.