Wild-type Corynebacterium glutamicum produces a mixture of lactic, succinic, and acetic acids from glucose under oxygen deprivation. We investigated the effect of CO2 on the production of organic ...acids in a two-stage process: cells were grown aerobically in glucose, and subsequently, organic acid production by nongrowing cells was studied under anaerobic conditions. The presence of CO2 caused up to a 3-fold increase in the succinate yield (1 mol per mol of glucose) and about 2-fold increase in acetate, both at the expense of l-lactate production; moreover, dihydroxyacetone formation was abolished. The redistribution of carbon fluxes in response to CO2 was estimated by using (13)C-labeled glucose and (13)C nuclear magnetic resonance (NMR) analysis of the labeling patterns in end products. The flux analysis showed that 97% of succinate was produced via the reductive part of the tricarboxylic acid cycle, with the low activity of the oxidative branch being sufficient to provide the reducing equivalents needed for the redox balance. The flux via the pentose phosphate pathway was low (~5%) regardless of the presence or absence of CO2. Moreover, there was significant channeling of carbon to storage compounds (glycogen and trehalose) and concomitant catabolism of these reserves. The intracellular and extracellular pools of lactate and succinate were measured by in vivo NMR, and the stoichiometry (H(+):organic acid) of the respective exporters was calculated. This study shows that it is feasible to take advantage of natural cellular regulation mechanisms to obtain high yields of succinate with C. glutamicum without genetic manipulation.
Purpose: This exploratory research evaluates if there a relationship between the number of years since an organization has achieved ISO 9001 certification and the highest level of recognition ...received by the same organization with the EFQM Business Excellence Model.Methodology/Approach: After state of the art review a detailed comparison between both models was made. Fifty two Portuguese organizations were considered and Correlation coefficient Spearman Rho was used to investigate the possible relationships.Findings: Conclusion is that there is indeed a moderate positive correlation between these two variables, the higher the number of years of ISO 9001 certification, the higher the results of the organization EFQM model evaluation and recognition. This supports the assumption that ISO 9001 International Standard by incorporating many of the principles present in the EFQM Business Excellence Model is consistent with this model and can be considered as a step towards that direction.Research Limitation/implication: Due to the dynamic nature of these models that might change over time and the possible time delays between implementation and results, more in-depth studies like experimental design or a longitudinal quasi-experimental design could be used to confirm the results of this investigation.Originality/Value of paper: This research gives additional insights on conjunct studies of both models. The use of external evaluation results carried out by the independent EFQM assessors minimizes the possible bias of previous studies accessing the value of ISO 9001 certification.
Palladium phthalocyanine (PdPc) nanowires (NWs) were developed to achieve the gas sensing of NO2 in the sub-parts-per-million (ppm) range. Non-substituted metal phthalocyanine are well known for ...their p-type semiconducting behavior, which is responsible for its gas-sensing capabilities. Nanofabrication of the PdPc NWs was performed by physical vapor deposition (PVD) on an interdigitated gold electrode (IDE). The coordination of palladium in the structure was confirmed with UV–Vis spectroscopy. Gas-sensing experiments for NO2 detection were undertaken at different sensed gas concentrations from 4 ppm to 0.5 ppm at room temperature. In this work, the responses at different gas concentrations are reported. In addition, structural studies of the PdPc NWs with scanning electron microscopy (SEM) and electron-dispersive X-ray diffraction (EDS) are shown.
The electrochemical features of microbial fuel cells’ biocathodes, running on wastewater, were evaluated by cyclic voltammetry. Ex situ and in situ electrochemical assays were performed and the redox ...processes associated with the presence of microorganisms and/or biofilms were attained. Different controls using sterile media (abiotic cathode microbial fuel cell) and membranes covering the electrodes were performed to evaluate the source of the electrochemistry response (surface biofilms vs. biotic electrolyte). The bacteria presence, in particular when biofilms are allowed to develop, was related with the enhanced active redox processes associated with an improved catalytic activity, namely for oxygen reduction, when compared with the results attained for an abiotic microbial fuel cell cathode. The microbial main composition was also attained and is in agreement with other reported studies. The current study aims contributing to the establishment of the advantages of using biocathodes rather than abiotic, whose conditions are frequently harder to control and to contribute to a better understanding of the bioelectrochemical processes occurring on the biotic chambers and the electrode surfaces.
We report universal approaches for porous nanowires (NWs), and porous NWs with spiral and meshy topologies that have been developed via anodic aluminum oxide (AAO) confined wet-chemical synthesis. ...Materials such as CuO x , Pd, and Cu NWs are taken as examples for porous NWs and porous NWs with spiral and meshy topologies. Immediate benefits are demonstrated in hydrogen sensors as examples. We observed that hydrogen concentrations as low as 0.2% (v/v) were detected, that critical temperatures of the reverse sensing behavior as low as 239.9 K were measured and that better baseline-stability was confirmed compared with those fabricated with pure Pd NWs. Our approaches are anticipated to work on the synthesis of the porous NWs of other materials that could be obtained via wet-chemistry with potential as candidates for the next generation nanodevices (e.g., gas sensors) and other applications (e.g., catalysts).
Carbon dioxide accumulation is a major concern for the ecosystems, but its abundance and low cost make it an interesting source for the production of chemical feedstocks and fuels. However, the ...thermodynamic and kinetic stability of the carbon dioxide molecule makes its activation a challenging task. Studying the chemistry used by nature to functionalize carbon dioxide should be helpful for the development of new efficient (bio)catalysts for atmospheric carbon dioxide utilization. In this work, the ability of Desulfovibrio desulfuricans formate dehydrogenase (Dd FDH) to reduce carbon dioxide was kinetically and mechanistically characterized. The Dd FDH is suggested to be purified in an inactive form that has to be activated through a reduction-dependent mechanism. A kinetic model of a hysteretic enzyme is proposed to interpret and predict the progress curves of the Dd FDH-catalyzed reactions (initial lag phase and subsequent faster phase). Once activated, Dd FDH is able to efficiently catalyze, not only the formate oxidation (k cat of 543 s–1, K m of 57.1 μM), but also the carbon dioxide reduction (k cat of 46.6 s–1, K m of 15.7 μM), in an overall reaction that is thermodynamically and kinetically reversible. Noteworthy, both Dd FDH-catalyzed formate oxidation and carbon dioxide reduction are completely inactivated by cyanide. Current FDH reaction mechanistic proposals are discussed and a different mechanism is here suggested: formate oxidation and carbon dioxide reduction are proposed to proceed through hydride transfer and the sulfo group of the oxidized and reduced molybdenum center, Mo6+S and Mo4+-SH, are suggested to be the direct hydride acceptor and donor, respectively.
Purpose
This paper aims to identify and characterize the motivations for ISO 9001 quality management system (QMS) implementation and certification, with a novel, valid and business-oriented scale ...applied to a large sample. Instead of adopting a normative approach focusing on the internal/external nature of the motivation, this investigation aims to emphasize the ISO 9001 driving forces from an instrumental (productivity, market and competitiveness) perspective.
Design/methodology/approach
This study is framed with a quantitative methodology supported by an email survey encompassing a sample of 526 Portuguese ISO 9001 certified organizations. Descriptive statistics, exploratory factorial analysis (EFA), t-tests and correlation analysis were performed according to the proposed research questions.
Findings
Regarding the motivations, three factors were obtained by applying EFA: market, productivity and competitiveness. The respondent organizations consider the productivity factor (mainly related to internal motivations) to be the most important. Concerning the other factors, competitiveness in the sector is ranked second and the reasons related to the market come in third. Additionally, organizations of medium dimension (between 50 and 249 employees), certified up to 1999 or from the private sector, give greater relevance to motivations related to the market and competitiveness.
Research limitations/implications
This investigation suffers from the limitations inherent to the survey methodology (e.g. potential bias) and a Portuguese sample’s restrictions. Moreover, this research does not cover organizations that have been certified after 2015, namely, with an initial ISO 9001:2015 certification. Nevertheless, most of the respondents’ organizations remain ISO 9001 certified today.
Practical implications
The information provided allows managers to know the driving forces and motivations behind seeking ISO 9001 certification. It can assist certification bodies in fine-tuning their marketing strategies to attract new customers and support ISO 9001 stakeholders in the ISO 9001 revision cycles.
Social implications
Policymakers can also adjust policies to foster ISO 9001 certification accordingly. Furthermore, as Wawak et al. (2020) suggested, with ISO starting a new revision cycle for ISO 9001, an increase in the research topic is expected. This study brings additional knowledge that can assist ISO stakeholders in that process.
Originality/value
This study presents a novel, valid and more business-oriented scale to characterize and identify the motivations for ISO 9001 QMS certification and maps the driving forces for ISO 9001 certification in a large sample size of diverse organizations. The instrumental nature of the scale (productivity, market and competitiveness) improves the consistency with recent research on ISO 9001 contributions for organizational performance compared with previous scales that focused on the internal/external nature of the motivation.
Biodegradable aliphatic polyester formulations as carriers for topical drug delivery show the potential to encapsulate structurally different therapeutic compounds. Poly(octamethylene suberate) (POS) ...nanoparticles (POS-NPs) were used as a matrix to encapsulate four therapeutic molecules used to treat skin disorders: caffeine (CF), quercetin (QR), hydrocortisone (HC), and adapalene (AD). Hydrophobicity and chemical structure of bioactive compounds (BCs) influenced the physicochemical stability of drug-loaded nanoparticles. The particle size of drug-loaded nanoparticles was between 254.9 nm for the CF-POS-NP and 1291.3 for QR-POS-NP. Particles had a negative charge from −27.6 mV (QR) to −49.2 mV (HC). Drug loading content for all BC-POS-NPs varies between 36.11 ± 1.48% (CF-POS-NP) and 66.66 ± 4.87% (AD-POS-NP), and their entrapment efficiency is relatively high (28.30 ± 1.81% and 99.95 ± 0.04%, respectively). Calorimetric analysis showed the appearance of polymorphism for AD- and HC-loaded systems and the drug’s complete solubilisation into all nanoparticle formulations. FTIR and NMR spectra showed apparent drug incorporation into the polymer matrix of NPs. The encapsulation of BCs enhanced the antioxidative effect. The prepared POS nanoparticles’ cytotoxicity was studied using two dermal cell lines, keratinocyte (HaCaT) cells and fibroblasts (HDFn). The nanoparticle cytotoxic effect was more substantial on HaCaT cell lines. A reconstructed human epidermis (RHE) was successfully used to investigate the penetration of polymeric NPs. Based on permeation and histology studies, HC-POS-NPs and CF-POS-NPs were shown not to be suitable for dermal applications with the explored drug concentrations. AD presents a high permeation rate and no toxic impact on RHE.
•JM-20 protects mitochondria and PC-12 cell against 6-OHDA toxicity.•JM-20 attenuates ROS generation in hemiparkinsonian rats.•JM-20 prevents motor damage in hemiparkinsonian rats.•JM-20 prevents ...astrogliosis and dopaminergic cell death.
We have previously shown that JM-20, a new chemical entity consisting of 1,5-benzodiazepine fused to a dihydropyridine moiety, protects against rotenone-induced neurotoxicity in an experimental model of Parkinson’s disease (PD). The aim of this study was to investigate the effect of a novel hybrid molecule, named JM-20, in in vitro and in vivo models of PD induced by 6-hydroxydopamine (6-OHDA). PC-12 cells were exposed to 6-OHDA and treated with JM-20. Protection against mitochondrial damage induced by 6-OHDA was also investigated using isolated rat brain mitochondria. We found that JM-20 protected PC-12 cells against cytotoxicity induced by 6-OHDA and inhibited hydrogen peroxide generation, mitochondrial swelling and membrane potential dissipation. For in vivo experiments, adult male Wistar rats were lesioned in the substantia nigra pars compacta (SNpc) by 6-OHDA administration. JM-20 was orally administered (10, 20 or 40 mg/kg), intragastric via gavage, 24 h after surgery and daily for seven days. Treatment with JM-20 significantly reduced the percentage of motor asymmetry and increased vertical exploration. It improved the redox state of the SNpc and the striatal tissue of these animals. Also, JM-20 reduced glial fibrillary acidic protein overexpression and increased tyrosine hydroxylase-positive cell number, both in SNpc. Altogether, these results demonstrate that JM-20 is a potential neuroprotective agent against 6-OHDA-induced damage in both in vitro and in vivo models. The mechanism underlying JM-20 neuroprotection against 6-OHDA appears to be associated with the control of oxidative injury and mitochondrial impairment.
Tin selenide (SnSe) has been the subject of great attention in the last years due to its highly efficient thermoelectricity and its possibilities as a green material, free of Pb and Te. Here, we ...report for the first time a thermoelectricity and transport study of individual SnSe micro- and nano-wires with diameters in the range between 130 nm and 1.15 μm. X-ray diffraction and transmission electron microscopy analyses confirm an orthorhombic SnSe structure with Pnma (62) symmetry group and 1:1 Sn:Se atomic ratio. Electrical and thermal conductivity and the Seebeck coefficient were measured in each individual nanowire using a specialized suspended microdevice in the 150-370 K temperature range, yielding a thermal conductivity of 0.55 Wm
K
at room temperature and ZT ~ 0.156 at 370 K for the 130 nm diameter nanowire. The measured properties were correlated with electronic information obtained by model simulations and with phonon scattering analysis. The results confirm these structures as promising building blocks to develop efficient temperature sensors, refrigerators and thermoelectric energy converters. The thermoelectric response of the nanowires is compared with recent reports on crystalline, polycrystalline and layered bulk structures.
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