Acoustic behavior design with simulated annealing

The present work extends the matrix method formalism, by using a supplementary computational method based on a simulated annealing algorithm, with the aim to design acoustical structures, especially acoustic filters. The algorithm introduces a cost function, which is minimized by the simulated annealing algorithm. Also, some numerical computations have been carried out to design some special acoustic filters and an experimental analysis of the designed acoustic filters is provided to test the validity of the method.     

Untersuchung des Verhaltens von Stählen unter wiederholter Schlagzugbeanspruchung

Versuchseinrichtung zur Durchführung von Schlagzugversuchen mit Ermittlung der verbrauchten Schlagarbeit. Schlagzugversuche an Rundproben mit 6, 7 und 8 mm Dmr. aus Stahl St 50. Anwendung von Schlagenergien zwischen 300 und 30 J. Ertragbare Anzahl der Schläge in Abhängigkeit von der spezifischen Schlagarbeit. Einfluß des Probendurchmessers auf die spezifische Dauerschlagarbeit. Bleibende Dehnung bei wiederholter Schlagzugbeanspruchung im Zusammenhang mit der Anzahl der Schläge, der Energie der Einzelschläge und der verbrauchten Gesamtenergie bis zum Bruch. Schlagwiderstand des Werkstoffes.     

The Roles of MicroRNAs in Male Infertility

MicroRNAs applications were vastly studied throughout the years, spanning from potential cancer biomarkers to targeted therapies for various diseases. Out of these utilizations, this paper focuses on their role in male infertility. Approximately 10–15% of worldwide couples are affected by infertility. Out of these, 50% are due to male determinants. The majority of cases still have an undetermined cause. Previous studies have found that the aberrant expression of microRNAs could be linked to certain reproductive dysfunctions in males. Further on, this study looked into the most recent literature published on this subject in order to assess the connection between the up-/down-regulation of various microRNAs and the roles they play in male infertility. MicroRNAs were found to be abundant and stable in the seminal liquid, which led to a facile identification using regular RNA detection methods. It was observed that the concentration of microRNAs in semen was modified in the case of patients suffering from asthenozoospermia and azoospermia. Moreover, idiopathic male infertility was associated with a single nucleotide polymorphism of the microRNA binding site. Future studies should focus their attention on discovering future treatments against male infertility targeting specific microRNAs and also on developing new and improved contraceptive methods.     

Pregnancy-Related Extracellular Vesicles Revisited

Extracellular vesicles (EVs) are small vesicles ranging from 20–200 nm to 10 μm in diameter that are discharged and taken in by many different types of cells. Depending on the nature and quantity of their content—which generally includes proteins, lipids as well as microRNAs (miRNAs), messenger-RNA (mRNA), and DNA—these particles can bring about functional modifications in the receiving cells. During pregnancy, placenta and/or fetal-derived EVs have recently been isolated, eliciting interest in discovering their clinical significance. To date, various studies have associated variations in the circulating levels of maternal and fetal EVs and their contents, with complications including gestational diabetes and preeclampsia, ultimately leading to adverse pregnancy outcomes. Furthermore, EVs have also been identified as messengers and important players in viral infections during pregnancy, as well as in various congenital malformations. Their presence can be detected in the maternal blood from the first trimester and their level increases towards term, thus acting as liquid biopsies that give invaluable insight into the status of the feto-placental unit. However, their exact roles in the metabolic and vascular adaptations associated with physiological and pathological pregnancy is still under investigation. Analyzing peer-reviewed journal articles available in online databases, the purpose of this review is to synthesize current knowledge regarding the utility of quantification of pregnancy related EVs in general and placental EVs in particular as non-invasive evidence of placental dysfunction and adverse pregnancy outcomes, and to develop the current understanding of these particles and their applicability in clinical practice.     

Influence of microfibrillated cellulose and soft biocomponent on the morphology and thermal properties of thermoplastic polyurethanes

Composite materials from thermoplastic polyurethanes (TPUs) with biodegradable segments and microfibrillated cellulose (MFC) were developed as alternatives to traditional materials used in packaging or biomedical applications. Two TPUs were synthesized by the prepolymer method starting from different soft segments, poly(ε-caprolactone)/poly(butylene adipate) (PUBA) or poly(ε-caprolactone)/poly(ethylene oxide) (PUEO), and isophorone diisocyanate/aliphatic chain extender. Proton nuclear magnetic resonance (¹H NMR) confirmed the structure and Fourier transform infrared spectroscopy (FTIR) along with scanning electron microscopy showed that the soft segments with different hydrophobicity led to a higher phase mixing in PUBA and improved microphase separation in PUEO. MFC was added in the TPUs with different soft segments to increase biocompatibility, strength, and degradation rate. A better thermal stability, a gradual increase of crystallinity and a better dispersion of MFC were noticed in PUEO composites compared to PUBA ones. The crystallinity increased with 78% and 50% in PUBA and PUEO composites with 5 wt% MFC compared to the neat polyurethanes showing the nucleating ability of MFC. In addition, the enhanced storage modulus, with 75% and 25% in PUEO and PUBA composites, highlighted the reinforcing efficiency of MFC. Therefore, the addition of MFC to the already synthesized TPUs allows tailoring the morphology and thermal properties of TPUs for industrial application.     

Surface properties,thermal, and mechanical characteristics of poly(vinyl alcohol)–starch‐bacterial cellulose composite films

Nanocomposite films for food packaging applications were developed using bacterial cellulose (BC) nanofibers in different amount in a poly(vinyl alcohol)/starch (PVA/St) matrix. In search of a better method to reduce the harmful ingredients in food packaging, the cellulose nanofibers were obtained by the mechanical defibrillation of BC pellicles thus avoiding the addition of chemicals in the final packaging material. Improved mechanical performances were obtained starting from just 1% BC nanofibers in PVA/St. Atomic force microscopy images showed a uniform dispersion of BC nanofibers on the surface of nanocomposites. A twofold increase of both tensile strength and modulus was obtained for 2 wt % BC in the composite. BC nanofibers have greatly improved the barrier properties of PVA/St matrix, a twofold increase of water vapor permeability being obtained for only 2 wt % BC nanofibers in the composite film. PVA/St/2BC was proposed as a high potential material for food packaging applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45800.     

Random-phase-shift Fizeau interferometer

A new and potentially cost efficient kind of vibration-tolerant surface measurement interferometer based on the Fizeau-principle is demonstrated. The crucial novelty of this approach is the combination of two optoelectronic sensors: an image sensor with high spatial resolution and an arrangement of photodiodes with high temporal resolution. The photodiodes continuously measure the random-phase-shifts caused by environmental vibrations in three noncollinear points of the test surface. The high spatial resolution sensor takes several "frozen" images of the test surface by using short exposure times. Under the assumption of rigid body movement the continuously measured phase shifts of the three surface points enable the calculation of a virtual plane that is representative for the position and orientation of the whole test surface. For this purpose a new random-phase-shift algorithm had to be developed. The whole system was tested on an optical table without vibration isolation under the influence of random vibrations. The analysis of the root-mean-square (RMS) over ten different measurements shows a measurement repeatability of about 0.004 wave (approximately 2.5 nm for 632.8 nm laser wavelength).     

Reconstruction dynamics of recorded holograms in photochromic glass

We have investigated the dynamics of the record-erase process of holograms in photochromic glass using continuum Nd:YVO? laser radiation (λ=532 nm). A bidimensional microgrid pattern was formed and visualized in photochromic glass, and its diffraction efficiency decay versus time (during reconstruction step) gave us information (D, Δn) about the diffusion process inside the material. The recording and reconstruction processes were carried out in an off-axis setup, and the images of the reconstructed object were recorded by a CCD camera. Measurements realized on reconstructed object images using holograms recorded at a different incident power laser have shown a two-stage process involved in silver atom kinetics.     

Considerations on CDMA–OFDM System Performances in Different Channel Environments for Different Modulation and Coding Scenarios

This paper presents a number of results obtained based on a CDMA–OFDM simulator developed in Matlab. The simulator has been extended to accommodate in a flexible manner to different modulation schemes, multiple access techniques, spreading codes types and lengths, convolutional codes rates, number of users and types of channels. The performances are evaluated and compared based on the Bit Error Rate (BER) as a function of the Signal to Noise Ratio (SNR) results achieved in different scenarios. In this paper are presented the results obtained by the developed simulator for two types of spreading codes—perfectly orthogonal Walsh type codes versus pseudo-orthogonal Gold type codes. The performances are evaluated in different channel environments the classical AWGN, pedestrian, vehicular and indoor ITU-R M.1225 models, for BPSK and QPSK modulations and 1/2 respectively 3/4 rate channel coding. Furthermore, since the results shown that the Gold spreading codes, QPSK modulation and 1/2 rate coding achieves the best performances in all type of channels analyzed, the authors investigate the effect of the code length and of the number of users on these results.