Heat of absorption of CO2 in aqueous N,N-diethylethanolamine + N-methyl-1,3-propanediamine solutions at 313 K

Differential heat of absorption of CO_2 in aqueous solutions of N,N-diethylethanolamine(DEEA) and activated DEEA solutions up to a total concentration of 2 mol·L~(-1) was measured as a function of CO_2 loading at 313.15 K using a reaction calorimeter. In order to analyze the performance of N-methyl-1,3-propanediamine(MAPA)as an activator, DEEA blended solutions containing 0.05, 0.1 and 0.2 mol·L~(-1) MAPA were studied. The heat of CO_2 absorption in single DEEA solutions was unaffected by changing the DEEA concentration in the range of(0.5–2) mol·L~(-1). On the other hand, increasing the concentration of MAPA in aqueous amine mixtures of(DEEA + MAPA) raised the heat of absorption.     

Effect of Polyhedral Oligomeric Silsesquioxanes Nanoparticles on Thermal and Mechanical Properties of Poly(vinyl chloride) Composite Materials

The modification of poly(vinyl chloride) (PVC) by polyhedral silsesquioxane containing both methacryl and octyl groups (MeOctPOSS) was the task of studies. The PVC nanocomposites with MeOctPOSS concentration between 1 and 10 wt% were prepared by melt mixing processing, and the homogeneity of MeOctPOSS dispersion in the polymeric matrix was confirmed by scanning electron microscopy and energy dispersive spectroscopy observations. The influence of MeOctPOSS on glass transition temperature (T_g) determined by means of dynamic mechanical thermal analysis (DMTA) and differential scanning calorimetry (DSC) was observed, whereas, higher the measurement frequency, higher the glass transition temperature was noted. The MeOctPOSS concentration‐dependent PVC glass transition temperature was shifted from 73.8°C to about 68°C (? = 1 Hz) and from 76.5°C to 70.8°C (? = 10 Hz) for increasing additive content. Similar result of decreasing T_g value was observed by DSC method. An introduction of 10 wt% of MeOctPOSS into the PVC matrix results in a visible decrease of the maximum value of loss modulus (G′) of approximately 12% and 18% by 1 Hz and 10 Hz, respectively, as well as in a significant reduction of the static elastic modulus. It was stated that the polyhedral oligomeric silsesquioxanes with both methacryl and octyl groups may act as plasticizers of the PVC matrix. J. VINYL ADDIT. TECHNOL., 25:E48–E54, 2019. © 2018 Society of Plastics Engineers     

Adaptive Narrowband Interference Suppression in Multiband OFDM Receivers

The analysis and optimization of a notch filter to combat in-band narrowband interference (NBI) for multiband orthogonal frequency division multiplexing (MB-OFDM)-based ultra-wideband (UWB) systems is presented. Unintentional radiation of electronic devices can reside in the UWB band and jam the communication. Erasing the interference with a programmable analog notch filter reduces the requirement for the analog-to-digital converter resolution in the presence of NBI. The order and approximation of the notch filter are determined, and the filter’s bandwidth is optimized to minimize the packet error rate. Simulation results indicate that the UWB system with suppression scheme can handle up to 14 dB more in-band interference power.     

Refractive-Index Profiling of Buried Planar Waveguides by an Inverse Wentzel–Kramer–Brillouin Method

We propose an inverse Wentzel-Kramer-Brillouin (WKB) method for the construction of the refractive-index profiles of buried graded-index planar waveguides from the measured effective indexes of the guided modes. Our method involves experimental determination of the location of the peak index in the buried profile, measurement of the effective indexes in air, and an index-matching liquid, and application of a searching algorithm to find the best-fit profile through inverting the WKB equations. We present numerical examples and experimental results to demonstrate the performance of the method.     

The Effect of Photoperiod on Necrosis Development,Photosynthetic Efficiency and ‘Green Islands’ Formation in Brassica juncea Infected with Alternaria brassicicola

The main goal of growing plants under various photoperiods is to optimize photosynthesis for using the effect of day length that often acts on plants in combination with biotic and/or abiotic stresses. In this study, Brassica juncea plants were grown under four different day-length regimes, namely., 8 h day/16 h night, 12 h day/12 h night, 16 h day/8 h night, and continuous light, and were infected with a necrotrophic fungus Alternaria brassicicola. The development of necroses on B. juncea leaves was strongly influenced by leaf position and day length. The largest necroses were formed on plants grown under a 16 h day/8 h night photoperiod at 72 h post-inoculation (hpi). The implemented day-length regimes had a great impact on leaf morphology in response to A. brassicicola infection. They also influenced the chlorophyll and carotenoid contents and photosynthesis efficiency. Both the 1st (the oldest) and 3rd infected leaves showed significantly higher minimal fluorescence (F₀) compared to the control leaves. Significantly lower values of other investigated chlorophyll a fluorescence parameters, e.g., maximum quantum yield of photosystem II (F_v/F_m) and non-photochemical quenching (NPQ), were observed in both infected leaves compared to the control, especially at 72 hpi. The oldest infected leaf, of approximately 30% of the B. juncea plants, grown under long-day and continuous light conditions showed a ‘green island’ phenotype in the form of a green ring surrounding an area of necrosis at 48 hpi. This phenomenon was also reflected in changes in the chloroplast’s ultrastructure and accelerated senescence (yellowing) in the form of expanding chlorosis. Further research should investigate the mechanism and physiological aspects of ‘green islands’ formation in this pathosystem.     

At the Edges of Photosynthetic Metabolic Plasticity—On the Rapidity and Extent of Changes Accompanying Salinity Stress-Induced CAM Photosynthesis Withdrawal

The common ice plant (Mesembryanthemum crystallinum L.) is a facultative crassulacean acid metabolism (CAM) plant, and its ability to recover from stress-induced CAM has been confirmed. We analysed the photosynthetic metabolism of this plant during the 72-h response period following salinity stress removal from three perspectives. In plants under salinity stress (CAM) we found a decline of the quantum efficiencies of PSII (Y(II)) and PSI (Y(I)) by 17% and 15%, respectively, and an increase in nonphotochemical quenching (NPQ) by almost 25% in comparison to untreated control. However, 48 h after salinity stress removal, the PSII and PSI efficiencies, specifically Y(II) and Y(I), elevated nonphotochemical quenching (NPQ) and donor side limitation of PSI (Y_ND), were restored to the level observed in control (C₃ plants). Swelling of the thylakoid membranes, as well as changes in starch grain quantity and size, have been found to be components of the salinity stress response in CAM plants. Salinity stress induced an over 3-fold increase in average starch area and over 50% decline of average seed number in comparison to untreated control. However, in plants withdrawn from salinity stress, during the first 24 h of recovery, we observed chloroplast ultrastructures closely resembling those found in intact (control) ice plants. Rapid changes in photosystem functionality and chloroplast ultrastructure were accompanied by the induction of the expression (within 24 h) of structural genes related to the PSI and PSII reaction centres, including PSAA, PSAB, PSBA (D₁), PSBD (D₂) and cp43. Our findings describe one of the most flexible photosynthetic metabolic pathways among facultative CAM plants and reveal the extent of the plasticity of the photosynthetic metabolism and related structures in the common ice plant.     

Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) in Physiological and Pathological Processes within the Gastrointestinal Tract: A Review

Pituitary adenylate cyclase-activating polypeptide (PACAP) is a neuropeptide widely distributed in the central nervous system (CNS) and many peripheral organs, such as the digestive tract, endocrine, reproductive and respiratory systems, where it plays different regulatory functions and exerts a cytoprotective effect. The multifarious physiological effects of PACAP are mediated through binding to different G protein-coupled receptors, including PAC1 (PAC1-R), VPAC1 (VPAC1-R) and VPAC2 (VPAC2-R) receptors. In the gastrointestinal (GI) tract, PACAP plays an important regulatory function. PACAP stimulates the secretion of digestive juices and hormone release, regulates smooth muscle contraction, local blood flow, cell migration and proliferation. Additionally, there are many reports confirming the involvement of PACAP in pathological processes within the GI tract, including inflammatory states, neuronal injury, diabetes, intoxication and neoplastic processes. The purpose of this review is to summarize the distribution and pleiotropic action of PACAP in the control of GI tract function and its cytoprotective effect in the course of GI tract disorders.     

The influence of hydrophobic substances on water vapor permeability of fish gelatin films modified with transglutaminase or 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)

The effect of different hydrophobic substances on water vapor permeability (WVP) of unmodified fish gelatin films and cross-linked with transglutaminase (TGase) or with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) was determined. Both unmodified and cross-linked films were characterized by very poor water barrier properties. Amaranth oil, rapeseed oil, lanolin, beeswax and ozococerite at concentration of 10% decreased WVP of unmodified gelatin films by 42, 15, 37, 53 and 36%, respectively. Increasing concentration of these substances up to 60% caused further improving of the water barrier properties. Addition of lecithin into film-forming emulsions prevented separation of lipid layer on the film surface. Among unmodified films with lecithin and 60% of lipids the highest decrease of WVP was found in case of amaranth oil and beeswax, by 73 and 87%, respectively, in comparison to only-gelatin films. WVP of chemically modified films in the presence of 60% of beeswax with addition of lecithin was decreased by about 65%. Enzymatically modified films with beeswax were very brittle and broke during analyzes, similarly as those with amaranth oil and lecithin. WVP of enzymatically modified films with lecithin and 60% of rapeseed oil and lanolin was respectively, about 60 and 47% lower than that of films without hydrophobic substances.