Transmit Diversity Schemes for WCDMA

Previous work on transmitter antenna diversity has shown that the use of multiple transmitter antennas at the base station results in improved performance due to increase of diversity (path diversity). This happens with no bandwidth cost, even when the signal quality along several paths is poor, but the receiver estimates the channel with accuracy. This paper evaluates the effects of channel estimation errors in the performance of the schemes designated as Space-Time Transmitter Diversity (STTD) and Selective Transmitter Diversity (STD). We consider low to medium signal to noise ratios characteristic of Wideband Code Division Multiple Access (WCDMA) networks. Different fading channel models are considered for comparison between the two schemes. The improvement due to convolutional coding associated with these techniques is also evaluated.     

Assessing the impact of performance determinants in complex MTO/ETO supply chains through an extended hybrid modelling approach

In make-to-order (MTO)/engineer-to-order (ETO) business environments multiple customer-oriented projects compete for and share resources through interdependent engineering and production activities. Deep knowledge of critical dimensions that affect performance is key in this context. For this, we propose a set of determinants – workload, complexity, outsourcing, design reuse, project type, and knowledge/experience with technology, that impact performance. These determinants are input to an extended hybrid simulation model using system dynamics (SD), discrete event simulation (DES) and agent-based simulation (ABS) that tackles the needs imposed by activities of very different nature, as the project development and manufacturing/assembly operations. The hybrid model is applied to the case of an advanced manufacturing company. Through Monte Carlo sampling, the influence of different combinations of determinants in the performance variability is assessed. A correlation analysis shows evidence of association between all performance determinants and the project time and cost, while no evidence of association between the design reuse and project type determinants and the manufacturing and assembly time.     

Protein Ligation-Assisted Reconstitution of Split HRP Fragments for Facile Production of HRP Fusion Proteins in E. coli

Horseradish peroxidase (HRP) is a pivotal biocatalyst for biosensor development and fine chemical synthesis. HRP proteins are mostly extracted and purified from the roots of horseradish because the solubility and productivity of recombinant HRP in bacteria are significantly low. In this study, we investigate the reconstitution system of split HRP fragments to improve its soluble expression levels in E. coli allowing the cost-effective production of bioactive HRPs. To promote the effective association between two HRP fragments (HRPn and HRPc), we exploit SpyTag-SpyCatcher chemistry, a versatile protein coupling method with high affinity and selectivity. Each HRP fragment was genetically fused with SpyTag and SpyCatcher, respectively, exhibiting soluble expression in the E. coli cytoplasm. The engineered split HRPs were effectively and irreversibly reconstituted into a biologically active and stable assembly that can catalyze intrinsic enzymatic reactions. Compared to the chaperone co-expression system, our approach shows that the production yield of soluble HRP is comparable, but the purity of the final product is relatively high. Therefore, our results can be applied to the high-yield production of recombinant HRP variants and other difficult-to-express proteins in bacteria without complex downstream processes.     

CFD as an approach to understand flammable dust 20 L standard test: Effect of the ignition time on the fluid flow

A computational study based on the Euler–Lagrange approach was developed for the characterization of flammable dusts in the 20 L sphere standard test. The aim of the study was to analyze some parameters that might affect the experimental data (e.g., cold turbulence and particle size). The turbulence of a wheat starch cloud was described with the Detached Eddy Simulation model. Both the pressure of the system and the RMS velocity were compared with the flow patterns established with a particle image velocimetry analysis. It was concluded that the rebound nozzle forms a cloud that is composed by clumps. This fact implies dissimilarities between the local concentrations and the nominal value. Finally, a granulometric analysis established that the mean diameter of the particle size distribution (PSD) decreased by 69% during the dispersion. Thus, it is suggested to consider the PSD at the ignition zone rather than the PSD of the sample. © 2017 American Institute of Chemical Engineers AIChE J, 63: 42–54, 2018     

Aging of HDPE Pipes Exposed to Diesel Lubricant

The effects caused upon the physicochemical behavior of high-density polyethylene pipes by exposure to a diesel lubricant were investigated, as a function of time and temperature, by thermogravimetric and gravimetric analysis and by FT-IR. The gravimetric data were satisfactorily described using Fick's law. The fitting of the experimental points showed that diesel, which can be regarded as a model fluid to analyze the effects caused by aromatic unities present in oil derivatives, has a high diffusion rate into HDPE. The FT-IR results showed that no main structural modifications have occurred after exposure, besides solubilization of low molecular weight units. From the analysis performed, physical aging was identified as the aging process occurring when the HDPE pipes came in contact with diesel lubricant.     

Binding of Sulpiride to Seric Albumins

The aim of this work was to study the interaction of sulpiride with human serum albumin (HSA) and bovine serum albumin (BSA) through the fluorescence quenching technique. As sulpiride molecules emit fluorescence, we have developed a simple mathematical model to discriminate the quencher fluorescence from the albumin fluorescence in the solution where they interact. Sulpiride is an antipsychotic used in the treatment of several psychiatric disorders. We selectively excited the fluorescence of tryptophan residues with 290 nm wavelength and observed the quenching by titrating HSA and BSA solutions with sulpiride. Stern-Volmer graphs were plotted and quenching constants were estimated. Results showed that sulpiride form complexes with both albumins. Estimated association constants for the interaction sulpiride–HSA were 2.20 (±0.08) × 10⁴ M⁻¹, at 37 °C, and 5.46 (±0.20) × 10⁴ M⁻¹, at 25 °C. Those for the interaction sulpiride-BSA are 0.44 (±0.01) × 10⁴ M⁻¹, at 37 °C and 2.17 (±0.04) × 10⁴ M⁻¹, at 25 °C. The quenching intensity of BSA, which contains two tryptophan residues in the peptide chain, was found to be higher than that of HSA, what suggests that the primary binding site for sulpiride in albumin should be located next to the sub domain IB of the protein structure.     

Catalytic Epoxidation and Sulfoxidation Activity of a Dioxomolybdenum(VI) Complex Bearing a Chiral Tetradentate Oxazoline Ligand

A dioxomolybdenum(vi) complex bearing a tetradentate anionic N,O oxazoline ligand with four stereocenters has been studied as a catalyst in the liquid-phase epoxidation of 17 different aliphatic and aromatic olefins (including prochiral, racemate or pure enantiomers) using tert-butyl hydroperoxide as the oxidant. Epoxide selectivities of up to 100% and variable epoxide yields (3–100% within 24 h) were obtained. Although the complex generally exhibited low or no chiral induction ability, diastereoselectivity was significant in some cases (in the reaction of limonene, for example). Kinetic studies and recycling tests with the substrates cis-cyclooctene and trans-β-methylstyrene showed that the catalyst is stable and reusable, and recycling is facilitated by immobilization of the complex in a room temperature ionic liquid. Preliminary results show that the complex may have a broad substrate scope, not only for olefin epoxidation, but also for the dehydrogenation of alcohols to carbonyl compounds and the sulfoxidation of sulfides to sulfoxides.     

Nanocomposite powders of hydroxyapatite-graphene oxide for biological applications

The repair of bone fractures is a clinical challenge for patients with impaired healing, such as osteoporosis. Currently, different strategies have been developed to design new biomaterials, enhancing their interactions with biological systems and conducting the cellular behavior in the desired direction to help fracture healing. In the present work, hydroxyapatite-graphene oxide (HA-GO) nanocomposites were produced and the morphological and physicochemical influences of the addition of 0.5 wt%, 1.0 wt% and 1.5 wt% of GO to HA were observed. FEG-SEM and TEM analyses of HA-GO nanocomposites showed HA nanoparticles adhered to the surface of the GO sheets, suggesting an effective method to form nanostructured graphene-based biomaterials. As confirmation, physicochemical analyses by Raman, FTIR and TGA demonstrated a strong affinity between HA and GO, according to the increase of concentration from 0.5 wt% to 1.5 wt% GO in the HA-GO nanocomposites. Also, in order to evaluate the HA-GO nanocomposites behavior under biological microenvironment, in vitro bioactivity and indirect cytotoxicity tests were performed. FEG-SEM analyses confirmed the positive results for the bioactivity properties of HA-GO nanocomposite and indirect cytotoxicity demonstrated that even with a decrease in the hDPSCs viability and proliferation, when increasing to 1.5 wt% of GO concentration, high level of cell viability was exhibited by HA-GO nanocomposites. These biological results suggested the 0.5 wt% HA-GO nanocomposite as a potential bioactive bone graft and a promising biomaterial for bone tissue regeneration, when compared to the pure HA.     

Spin-Crossover Grafted Monolayer of a Co(II) Terpyridine Derivative Functionalized with Carboxylic Acid Groups

The synthesis and characterization of a new Co(II) spin-crossover (SCO) complex based on 4′-(4-carboxyphenyl)−2,2′:6′,2″-terpyridine ligand are reported. This complex can be successfully grafted on silver surface maintaining the SCO behavior. Thus, atomic force microscopy (AFM), matrix assisted laser desorption ionization – time-of-flight mass spectrometry (MALDI-TOF MS), Raman spectroscopy, and XPS measurements, upon surface deposition, evidence the formation of a monolayer of intact molecules grafted through carboxylate groups to the Ag surface. Three different techniques: Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS), supported by first-principles calculations, confirm that the deposited molecules undergo a gradual spin transition with temperature. This phenomenon is unprecedented for a monolayer of molecules directly grafted onto a metallic surface from solution.