Reactor and Product Optimization via Raman Fiber Optics Monitoring: Application to Polymer‐Based Proppants

A setup to characterize polymerization kinetics of polymer‐based proppants produced in an industrial batch reactor by suspension polymerization is presented. A microscale reactor is designed to mimic temperature and pressure conditions of the industrial counterpart. Raman spectroscopy is used to follow the consumption of vinyl bonds of the styrene monomer and the crosslinker via disappearance of the peak at 1632 cm^‐1. Raman data from the microscale reactor are remotely obtained via a fiber optics system. Reaction progress by any generic formulation can be safely followed up to conversions of 90%, well beyond the gel point. Reaction rates are used to define feasible temperature–time profiles for the industrial reactor. In parallel, bulk and suspension polymerizations are carried out under those temperature–time profiles in a 3 L laboratory reactor to produce proppants formulations with the geometry required to perform product characterization, mainly focused on the thermal and mechanical response of the polymer particles. Overall, the whole setup allows optimization of proppant formulations and the cost of their processes of production.     

Inspection on the Mechanism of SARS-CoV-2 Inhibition by Penciclovir: A Molecular Dynamic Study

In recent years, humanity has had to face a critical pandemic due to SARS-CoV-2. In the rapid search for effective drugs against this RNA-positive virus, the repurposing of already existing nucleotide/nucleoside analogs able to stop RNA replication by inhibiting the RNA-dependent RNA polymerase enzyme has been evaluated. In this process, a valid contribution has been the use of in silico experiments, which allow for a rapid evaluation of the possible effectiveness of the proposed drugs. Here we propose a molecular dynamic study to provide insight into the inhibition mechanism of Penciclovir, a nucleotide analog on the RNA-dependent RNA polymerase enzyme. Besides the presented results, in this article, for the first time, molecular dynamic simulations have been performed considering not only the RNA-dependent RNA polymerase protein, but also its cofactors (fundamental for RNA replication) and double-strand RNA.     

Ueber die Nachweisung von Jodkalium im Urin

Ohne Zusammenfassung     

Signal recognition and signature code acquisition in CDMA mobilepacket communications

Fast and reliable signal sense and signature code synchronization for direct-sequence spread-spectrum (DS-SS) signals are key issues in the design of the receiver for modern packet code-division multiple-access (CDMA) radio networks for mobile communications; this motivates the study of the signal recognition and code-acquisition (SR/CA) scheme we describe in this paper. Specifically, starting from elementary estimation and detection theory criteria, we work out a noncoherent parallel SR/CA algorithm that is suited to a full-digital implementation in a single application-specific integrated circuit (ASIC). The results of a theoretical analysis of such a scheme, encompassing additive white Gaussian noise (AWGN) and multiple-access interference (MAI), are integrated and validated by an overall time-domain system simulation. We also evaluate through a simplified approach the impact of some degradation factors on the overall circuit performance, namely, sampling epoch and carrier frequency offset and 1-b signal quantization, to allow optimization of the design parameters as a function of the characteristics of the received signal     

Determination of nandrolone metabolites in human urine: comparison between liquid chromatography/tandem mass spectrometry and gas chromatography/mass spectrometry

Nandrolone (19‐nortestosterone) is an androgenic anabolic steroid illegally used as a growth‐promoting agent in animal breeding and as a performance enhancer in athletics. Therefore, its use was officially banned in 1974 by the Medical Commission of the International Olympic Committee (IOC). Following nandrolone administration, the main metabolites in humans are 19‐norandrosterone, 19‐norethiocolanolone and 19‐norepiandrosterone, and their presence in urine is the basis of detecting its abuse. The present work was undertaken to determine, in human urine, nandrolone metabolites (phase I and phase II) by developing and comparing multiresidue liquid chromatography/tandem mass spectrometry (LC/MS/MS) and gas chromatography/mass spectrometry (GC/MS) methods. A double extraction by solid‐phase extraction (SPE) was necessary for the complete elimination of the interfering compounds. The proposed methods were also tested on a real positive sample, and they allow us to determine the conjugated/free fractions ratio reducing the risk of false positive or misleading results and they should allow laboratories involved in doping control analysis to monitor the illegal use of steroids. The advantages of LC/MS/MS over GC/MS (which is the technique mainly used) include the elimination of the hydrolysis and derivatization steps: it is known that during enzymatic hydrolysis several steroids can be converted into related compounds and deconjugation is not always 100% effective. The validation parameters for the two methods were similar (limit of quantification (LOQ) <1 ng/mL and percentage coefficient of variance (CV%) <16.4), and both were able to confirm unambiguously all the analytes, thus confirming the validity of both techniques. Copyright © 2010 John Wiley & Sons, Ltd.     

VLSI implementation of a signal recognition and code acquisitionalgorithm for CDMA packet receivers

The widespread application of direct-sequence spread-spectrum code division multiple access (DS/SS-CDMA) to wireless communication systems asks for ever faster and more reliable real-time signal processing operations to be performed by highly integrated and low-power consumption digital receivers. One of the most critical signal processing tasks to be performed by the DS/SS-CDMA receiver is signal presence detection and code epoch estimation. This paper deals with the design and realization of an application-specific integrated-circuit (ASIC) for fast signal recognition and code acquisition (SR/CA) in packet DS/SS-CDMA receivers operating in a satellite or terrestrial radio network. In particular, we show how a parallel acquisition circuit can be effectively implemented on a single-chip with a 1.0-μm CMOS technology according to the specifications of the ARCANET Ku-band CDMA VSAT satellite network sponsored by the European Space Agency (ESA). It is shown that the ASIC performance closely follows analytical predictions     

Can mathematics educate for peace?

In this paper we simulate a discussion with our students, in which we alternate specific mathematical issues (as the PERT (Program Evaluation and Review Technique) in 1.2, a discrete dynamical system in 2.1 and fractals in 2.2) that can be applied in situations such as the evolution of populations (2.1) or other well-known contexts such as the economic equilibrium theory or the ecological systems. The students are given occasions to deepen both the meaning and use of the studied model. We emphasize those cases where the model leads to analyses of behaviour depending on parameters whose values highlight stable states of dynamic systems (regions of peace) and regions where control over the system evolution is lost, and where the system passes from bifureations to chaos (regions of war).