In vivo instability of chorismate causes substrate loss during fermentative production of aromatics

Metabolic engineering of microbial strains to produce aromatic compounds deriving from the shikimate pathway is of great interest to the chemical industry as a more sustainable alternative for feedstock production. Chorismate is a significant intermediate in the shikimate pathway. In this study, the formation of phenylalanine and phenylpyruvate as by‐products in strains engineered downstream of the chorismate node for increased aromatic production was explored in yeast fermentations. Tracer experiments showed that these compounds are synthesized de novo during fermentation, under conditions in which their synthesis was genetically blocked. Chorismate stability evaluation, as well as deletion mutation analysis throughout the phenylalanine biosynthesis pathway, suggested that this synthesis was a result of intracellular, non‐enzymatic rearrangement of chorismate to phenylpyruvate via prephenate, which was followed by enzymatic transamination of phenylpyruvate to form phenylalanine. These results not only aid in the development of strain‐engineering strategies to avoid the accumulation of by‐products during fermentations aimed at increased aromatics production, but also deepen our understanding of yeast metabolism. Copyright © 2014 John Wiley & Sons, Ltd.     

ATP hydrolysis induces an intermediate conformational state in GroEL

The conformational properties of the molecular chaperone GroEL in the presence of ATP, its non-hydrolyzable analog 5'-adenylimidodiphosphate (AMP-PNP), and ADP have been analyzed by differential scanning calorimetry (DSC), Fourier-transform infra-red (FT-IR) and fluorescence spectroscopy. Nucleotide binding to one ring promotes a decrease in the Tm value of the GroEL thermal transition that is reversed when both rings are filled with nucleotide, indicating that the sequential occupation of the two protein rings by these nucleotides has different effects on the GroEL thermal denaturation process. In addition, ATP induces a conformational change in GroEL characterized by (a) the appearance of a reversible low temperature endotherm in the DSC profiles of the protein, and (b) an enhanced binding of the hydrophobic probe 8-anilino-naphthalene-1-sulfonate (ANS), which strictly depends on ATP hydrolysis. The similar sensitivity to K+ of the temperature range where activation of the GroEL ATPase activity, the low temperature endotherm, and the increase of the ANS fluorescence are abserved strongly indicates the existence of a conformational state of GroEL during ATP hydrolysis, different from that generated on ADP or AMP-PNP binding. To achieve this intermediate conformation, GroEL mainly modifies its tertiary and quaternary structures, leading to an increased exposure of hydrophobic surfaces, with minor rearrangements of its secondary structure.     

Genetically engineered pfabA pfabR bacteria: an electrochemical whole cell biosensor for detection of water toxicity

We describe here a bacterial sensor for electrochemical detection of toxic chemicals. The sensor constitutes recombinant bacteria harboring plasmids encoding the fabA and fabR genes and has high-resolution amperometric response to membrane-damaging chemicals. For example, it can detect phenol at concentrations ranging between 1.6 and 16 ppm within 20 min. The high sensitivity is achieved by using the fabA promoter fused to a reporter gene-encoded beta-galactosidase on a low copy number plasmid, under the control of the FabR repressor. The use of electrochemical whole cell sensors enables sensitive, fast, easy to operate, and cost-effective detection of water toxicity threats.     

Spin-dependent plasmonics based on interfering topological defects

Observation of spin-dependent plasmonics based on the interference of topological defects in the near-field is presented. We utilize the surface plasmons' scattering dynamics from localized vortex sources to create spinoptical devices as an ensemble of isolated nanoantennas to observe a "giant" spin-dependent plasmonic vortex and a spin-dependent plasmonic focusing lens. The spin-orbit point spread function, a spiral wavefront, is introduced, where the optical spin is a degree of freedom.     

In-plane magnetic anisotropy and temperature dependence of switching field in (Ga, Mn) as ferromagnetic semiconductors

We explore the magnetic anisotropy of GaMnAs ferromagnetic semiconductor by Planar Hall Effect (PHE) measurements. Using low magnitude of applied magnetic field (i.e., when the magnitude H is smaller than both cubic Hc and uniaxial Hu anisotropy field), we have observed various shapes of applied magnetic field direction dependence of Planar Hall Resistance (PHR). In particular, in two regions of temperature. At T < Tc/2, the "square-shape" signal and at T > Tc/2 the "zigzag-shape" signal of PHR. They reflect different magnetic anisotropy and provide information about magnetization reversal process in GaMnAs ferromagnetic semiconductor. The theoretical model calculation of PHR based on the free energy density reproduces well the experimental data. We report also the temperature dependence of anisotropy constants and magnetization orientations. The transition of easy axis from biaxial to uniaxiale axes has been observed and confirmed by SQUID measurements.     

Synthesis and properties of a water-soluble ionic conjugated polymer with carboxylic acids

A new water-soluble ionic conjugated polymer, poly[N-(carboxymethyl)-2-ethynylpyridinium bromide], was prepared by the activated polymerization of 2-ethynylpyridine by using bromoacetic acid. This polymerization proceeded well in mild reaction conditions without any additional initiator or catalyst. The polymer structure was characterized by various instrumental methods to have a conjugated polymer backbone system with the designed functional groups. The photoluminescence spectrum of polymer showed that the PL peak is located at 603 nm corresponding to the photon energy of 2.06 eV. The cyclovoltammograms of polymer exhibited the irreversible electrochemical behaviors between the oxidation and reduction peaks. The oxidation current density of polymer versus the scan rates is approximately linear relationship in the range of 30 mV/sec-150 mV/sec. It was found that the kinetics of the redox process of polymer is almost controlled by the reactant diffusion process from the oxidation current density of polymer versus the scan rates.     

High efficiency, solution-processed, red phosphorescent organic light-emitting diodes from a polymer doped with iridium complexes

High efficiency, solution-processed, red emissive phosphorescent organic light-emitting diodes (PhOLEDs) have been developed. The PhOLEDs utilize bis[9-ethyl-3-(4-phenylquinolin-2-yl)-9H-carbazolato-N,C²′]iridium picolinate (Et-Cvz-PhQ)₂Ir(pic) and bis[9-(2-(2-methoxyethoxy)ethyl)-3-(4-phenylquinolin-2-yl)-9H-carbazolato-N,C²′]iridium picolinate (EO-Cvz-PhQ)₂Ir(pic) in a nonconjugated polymer host of PVK that contains the electron transport material of OXD-7 and the hole transport material TPD. The electroluminescence (EL) spectra of the PhOLEDs parallel those of (Et-Cvz-PhQ)₂Ir(pic) and (EO-Cvz-PhQ)₂Ir(pic) with maxima at 608 nm and a CIE (Commission International de l’Eclairage) coordinate of (0.62, 0.38). The red emitting PhOLEDs, based on ITO/PEDOT:PSS/PVK:OXD-7:TPD:Ir complex/cathode configuration, have a maximum external quantum efficiency of 10.6% and a luminance efficiency of 17.5 cd/A. The efficiency is significantly higher than those obtained using common solution-processed red emissive PhOLEDs.     

Real-time image texture analysis in quality management using grid computing: an application to the MDF manufacturing industry

Computer vision has arisen as one of the most important application areas in manufacturing processes. This work shows a new real-time texture analysis for medium-density fiberboard with melamine paper, using edge detection techniques and threshold detection methods. To minimize the time of identification of defects, the images of fiberboard are sent to a grid system. In a first phase, several tests are carried out using different image resolutions and sizes. In a second phase, to optimize the system, with the best resolution obtained and using a grid system, our aim is to minimize the time of detection of possible defects without jeopardizing the performance of the quality control system. Results show that, using accurate resolutions, the error detection process is quicker and the defect identification rate significantly improves.     

ASSØCA: FORTRAN IV program for Williams and Lambert Association analysis with printed dendrograms

A general-purpose computer program implementing Williams and Lambert's method of association analysis is documented. The method embodies a hierarchical-divisive-monothetic strategy for the numerical classification of multiattribute, binary-coded data sets. The main user-controlled options permit a selection from among two different association coefficients and three termination criteria; employment of Yates' correction; presetting significance thresholds; discarding insignificant association coefficients; treatment of ambiguities in dividing attributes; and the transformation of quantitative measurements to a binary-coded form. A line-printer dendrogram plot displaying the final classification is generated as part of the output. Both normal and inverse association analysis can be performed.     

Cities under fire: Crisis communication on home front versus frontline cities' Facebook pages during operation ‘guardian of the walls’

Social media has been widely adopted by local governments during emergencies and crises and its role as a communication platform has been discussed in various studies on natural hazards, pandemics and terror attacks. However, research in the field has not addressed how municipalities use social media to communicate valuable information during armed conflicts and military operations. The current study examined the ways five major cities in Israel used their Facebook pages to connect to their residents during operation ‘Guardian of the Walls' in 2021. We examined the social media usage and the strategies of these cities during the 12 days of the operation. The findings revealed significant differences between cities that are considered as home front versus frontline regions regarding content type and information dissemination strategies. Additionally, differences regarding content types in terms of sentiment and overall rates of engagement were also identified. These findings highlight the need to further investigate local municipalities' usage of social media during armed conflicts concerning the civil population.