Highlights • LED light requirements may be related to the evolutionary history of endosymbiosis. • Red or blue LEDs are often the most effective artificial light sources for microalgae. • LED light ...quality influences the growth and biochemistry of microalgae. • LEDs are ideal for building tailored light sources.
The history of SnO2-based voltage-dependent resistors is reviewed, and the main characteristics of these polycrystalline semiconductor systems are discussed, including a direct comparison with ...traditional ZnO-based voltage-dependent resistor systems to establish the differences and similarities, giving details of the basic physical principles involved with the non-ohmic properties in both polycrystalline systems. The main difficulties involved in processing SnO2- and ZnO-based non-ohmic systems are described, with an evaluation of the contribution of the dopants to the electronic properties and to the final microstructure and consequently to the non-ohmic behaviour of the system. The main focus is on the SnO2-based varistor systems, but the basic physical principles described are universally useful in the context of dense polycrystalline devices. New perspectives for applications, commercialisation and degradation studies involving SnO2-based polycrystalline non-ohmic systems are outlined, including recent technological developments. A brief section is dedicated to the presentation and discussions about other emerging non-ohmic polycrystalline ceramic devices (particularly based on perovskite ceramics) which must be studied in depth in the years to come, because some of these systems present combined high dielectric and non-ohmic properties. 164 refs.
Bulk Cu compounds such as Cu(OH)2 are extensively used as pesticides in agriculture. Recent investigations suggest that Cu-based nanomaterials can replace bulk materials reducing the environmental ...impacts of Cu. In this study, stress responses of alfalfa (Medicago sativa L.) seedlings to Cu(OH)2 nanoparticle or compounds were evaluated. Seeds were immersed in suspension/solutions of a Cu(OH)2 nanoform, bulk Cu(OH)2, CuSO4, and Cu(NO3)2 at 25 and 75 mg/L. Six days later, the germination, seedling growth, and the physiological and biochemical responses of sprouts were evaluated. All Cu treatments significantly reduced root elongation (average = 63%). The ionic compounds at 25 and 75 mg/L caused a reduction in all elements analyzed (Ca, K, Mg, P, Zn, and Mn), excepting for S, Fe and Mo. The bulk-Cu(OH)2 treatment reduced K (48%) and P (52%) at 75 mg/L, but increased Zn at 25 (18%) and 75 (21%) mg/L. The nano-Cu(OH)2 reduced K (46%) and P (48%) at 75 mg/L, and also P (37%) at 25 mg/L, compared with control. Confocal microscopy images showed that all Cu compounds, at 75 mg/L, significantly reduced nitric oxide, concurring with the reduction in root growth. Nano Cu(OH)2 at 25 mg/L upregulated the expression of the Cu/Zn superoxide dismutase gene (1.92-fold), while ionic treatments at 75 mg/L upregulated (∼10-fold) metallothionein (MT) transcripts. Results demonstrated that nano and bulk Cu(OH)2 compounds caused less physiological impairments in comparison to the ionic ones in alfalfa seedlings.
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•All Cu treatments reduced root elongation.•All Cu treatments at 75 mg/L differentially reduced the nitric oxide accumulation.•Nano Cu(OH)2 at 25 mg/L upregulated expression of Cu/Zn SOD.•Ionic treatments at 75 mg/L upregulated metallothionein transcripts.
This study provides initial mechanistic insights concerning the effects of Cu compound effects in alfalfa seedlings’ elemental composition and gene expression levels.
Cardiovascular diseases (CVD) are the most important cause of mortality globally. Nevertheless, the World Health Organization have declared that a precise and quick recognition of susceptible ...individuals to develop CVD is imperative to combat those illnesses. Additionally, developing countries need affordable alternatives to effectively prognosticate cardiovascular events. Therefore, the objective of this study was to assess well-established clinical prognostic markers in Mexican women to identify affordable, specific, and useful tools to predict cardiovascular events.
A cross-sectional study was performed including 340 healthy women. Anthropometric and clinical measurements were acquired from all enrolled individuals. Also, a blood sample of each participant women was obtained to complete biochemical analyses (triglycerides, glucose, total cholesterol, LDL cholesterol, and HDL cholesterol), and serum asymmetric dimethylarginine (ADMA), and adipocyte-fatty acid binding protein (FABP4) determinations. Finally, with anthropometric, clinical and biochemical determinations, atherogenic indices (Framingham risk score, Castelli's risk index, and atherogenic index of plasma) were estimated.
A mean value of 6.5 ± 7.2 was detected for the Framingham risk score, 3.7 ± 1.3 for Castelli's risk index, and 0.12 ± 0.22 for the atherogenic index of plasma (AIP). Circulating mean ADMA and FABP4 levels found in assessed women were 0.68 ± 0.34 mmol/L and 20.3 ± 16.6 ng/mL, respectively. Furthermore, strong positive relationships (p <0.05) between AIP and serum FABP4 and ADMA concentrations were detected after adjustment by traditional CVD risk factors.
In conclusion, AIP could be recommended as a potential biomarker in the early diagnosis of CVD events in developing countries.
The isolation of simultaneously low‐coordinate and low‐valent compounds is a timeless challenge for preparative chemists. This work showcases the preparation and full characterization of ...tri‐coordinate rhodium(‐I) and rhodium(0) complexes as well as a rare rhodium(I) complex. Reduction of {Rh(μ‐Cl)(IPr)(dvtms)}2 (1, IPr=1,3‐bis(2,6‐diisopropylphenyl)imidazolyl‐2‐ylidene; dvtms=divinyltetramethyldisiloxane) with KC8 gave the trigonal complexes KRh(IPr)(dvtms) and Rh(IPr)(dvtms), whereas the cation Rh(IPr)(dvtms)+ results from their oxidation or by ion of chloride from 1 with silver salts. The paramagnetic Rh0 complex is a unique fully metal‐centered radical with the unpaired electron in the dz2 orbital. The Rh(‐I) complex reacts with PPh3 with replacement of the NHC ligand, and behaves as a nucleophile, which upon reaction with AuCl(PPh3) generates the trigonal pyramidal complex (IPr)(dvtms)Rh‐Au(PPh3) with a metal–metal bond between two d10 metal centers.
Trigonal‐planar rhodium complexes in low oxidation states are feasible by combination of a highly flexible diolefin and a bulky ligand. One‐electron oxidation of the diamagnetic Rh(‐I) complex gives the paramagnetic Rh0 counterpart, a unique metal‐centered radical with the unpaired electron in the dz2 orbital. Code color: Rh (yellow), K (pink), Si (green), O (red), N (blue), C (gray).
The feasibility of oxidative addition of the P−H bond of PHPh2 to a series of rhodium complexes to give mononuclear hydrido‐phosphanido complexes has been analyzed. Three main scenarios have been ...found depending on the nature of the L ligand added to Rh(Tp)(C2H4)(PHPh2) (Tp= hydridotris(pyrazolyl)borate): i) clean and quantitative reactions to terminal hydrido‐phosphanido complexes RhTp(H)(PPh2)(L) (L=PMe3, PMe2Ph and PHPh2), ii) equilibria between RhI and RhIII species: RhTp(H)(PPh2)(L)⇄RhTp(PHPh2)(L) (L=PMePh2, PPh3) and iii) a simple ethylene replacement to give the rhodium(I) complexes Rh(κ2‐Tp)(L)(PHPh2) (L=NHCs‐type ligands). The position of the P−H oxidative addition–reductive elimination equilibrium is mainly determined by sterics influencing the entropy contribution of the reaction. When ethylene was used as a ligand, the unique rhodaphosphacyclobutane complex Rh(Tp)(η1‐Et)(κC,P‐CH2CH2PPh2) was obtained. DFT calculations revealed that the reaction proceeds through the rate limiting oxidative addition of the P−H bond, followed by a low‐barrier sequence of reaction steps involving ethylene insertion into the Rh−H and Rh−P bonds. In addition, oxidative addition of the P−H bond in OPHPh2 to Rh(Tp)(C2H4)(PHPh2) gave the related hydride complex RhTp(H)(PHPh2)(POPh2), but ethyl complexes resulted from hydride insertion into the Rh−ethylene bond in the reaction with Rh(Tp)(C2H4)2.
Combination of tridentate hydrido‐tris(pyrazolyl)borate and phosphane ligands on rhodium provides a useful platform for the selective oxidative addition reaction of P−H bonds, ethylene insertion reactions into Rh−H bonds as well as P−C bond formation reactions of non‐activated olefins such as ethylene.
A strong greenish-light photoluminescence (PL) emission was measured at room temperature for disordered and ordered powders of CaMoO4 prepared by the polymeric precursor method. The structural ...evolution from disordered to ordered powders was accompanied by XRD, Raman spectroscopy, and TEM imagery. High-level quantum mechanical calculations in the density functional framework were used to interpret the formation of the structural defects of disorder powders in terms of band diagram and density of states. Complex cluster vacancies MoO3·VO z and CaO7·VO z (where VO z = V O X , VO •, VO ••) were suggested to be responsible to the appearance of new states shallow and deeply inserted in the band gap. These defects give rise to the PL in disordered powders. The natural PL emission of ordered CaMoO4 was attributed to an intrinsic slight distortion of the MoO4 tetrahedral in the short range.
Materials with high photoluminescence (PL) intensity can potentially be used in optical and electronic devices. Although the PL properties of bismuth(III) oxide with a monoclinic crystal structure ...(α-Bi2O3) have been explored in the past few years, methods of increasing PL emission intensity and information relating PL emission to structural defects are scarce. This research evaluated the effect of a pressure-assisted heat treatment (PAHT) on the PL properties of α-Bi2O3 with a needlelike morphology, which was synthesized via a microwave-assisted hydrothermal (MAH) method. PAHT caused an angular increase between the BiO6–BiO6 clusters of α-Bi2O3, resulting in a significant increase in the PL emission intensity. The Raman and XPS spectra also showed that the α-Bi2O3 PL emissions in the low-energy region (below ∼2.1 eV) are attributed to oxygen vacancies that form defect donor states. The experimental results are in good agreement with first-principles total-energy calculations that were carried out within periodic density functional theory (DFT).
Bioaccumulation patterns of heavy metals (Pb, Cd, Cr, Ni, Fe and Cu) and organic (priority and emerging) pollutants, in combination with stable isotope analysis (SIA), were assessed in muscle and ...liver of three tuna species from the Gulf of Cadiz (Atlantic bluefin tuna, Thunnus thynnus; Atlantic bonito, Sarda sarda, and skipjack tuna, Katsuwonus pelamis). SIA and contaminant (heavy metal and organic) profiles separately discriminated between species. There was no significant overlap between the trophic niches estimated from isotopic data, suggesting that there are diet differences which may determine differential bioaccumulation patterns. The levels of heavy metals and persistent organic pollutants in muscle of all the individuals analyzed were below the allowable limits established by the current legislation. Concentrations of most contaminants were higher in liver than in muscle, underlining the powerful detoxifying capacity of the liver in tunas. In addition to diet, other factors such as size and age (exposure time to environmental chemicals) explain differences in pollutant accumulation patterns in tissues between species, each with varying degrees of involvement depending on the pollutant class. Our results show that combining contaminant profile data with trophic features based on SIA may help understand pollutant bioaccumulation patterns in upper levels of marine food webs.
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•Muscle & liver levels of metals and organic pollutants were analyzed in 3 tuna spp.•Bioaccumulation patterns were related to trophic features based on isotopic analyses.•Heavy metal & organic (priority & emerging) pollutant levels were higher in liver.•Differences in isotopic data and pollutant levels resulted in segregation between spp.•Bioaccumulation patterns are likely linked to age (lifespan), size & trophic features.
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