Covariant derivative of the curvature tensor of pseudo-K\"ahlerian manifolds

It is well known that the curvature tensor of a pseudo-Riemannian manifold can be decomposed with respect to the pseudo-orthogonal group into the sum of the Weyl conformal curvature tensor, the traceless part of the Ricci tensor and of the scalar curvature. A similar decomposition with respect to the pseudo-unitary group exists on a pseudo-K\"ahlerian manifold; instead of the Weyl tensor one obtains the Bochner tensor. In the present paper, the known decomposition with respect to the pseudo-orthogonal group of the covariant derivative of the curvature tensor of a pseudo-Riemannian manifold is refined. A decomposition with respect to the pseudo-unitary group of the covariant derivative of the curvature tensor for pseudo-K\"ahlerian manifolds is obtained. This defines natural classes of spaces generalizing locally symmetric spaces and Einstein spaces. It is shown that the values of the covariant derivative of the curvature tensor for a non-locally symmetric pseudo-Riemannian manifold with an irreducible connected holonomy group different from the pseudo-orthogonal and pseudo-unitary groups belong to an irreducible module of the holonomy group.Comment: the final version accepted to Annals of Global Analysis and Geometr

Use of Copper-Based Fungicides in Organic Agriculture in Twelve European Countries

The reduction of copper-based plant-protection products with the final aim of phasing out has a high priority in European policy, as well as in organic agriculture. Our survey aims at providing an overview of the current use of these products in European organic agriculture and the need for alternatives to allow policymakers to develop strategies for a complete phasing out. Due to a lack of centralized databases on pesticide use, our survey combines expert knowledge on permitted and real copper use per crop and country, with statistics on organic area. In the 12 surveyed countries (Belgium, Bulgaria, Denmark, Estonia, France, Germany, Hungary, Italy, Norway, Spain, Switzerland, and the UK), we calculated that approximately 3258 t copper metal per year is consumed by organic agriculture, equaling to 52% of the permitted annual dosage. This amount is split between olives (1263 t y−1, 39%), grapevine (990 t y−1, 30%), and almonds (317 t y−1, 10%), followed by other crops with much smaller annual uses (<80 t y−1). In 56% of the allowed cases (countries × crops), farmers use less than half of the allowed amount, and in 27%, they use less than a quarter. At the time being, completely abandoning copper fungicides would lead to high yield losses in many crops. To successfully reduce or avoid copper use, all preventive strategies have to be fully implemented, breeding programs need to be intensified, and several affordable alternative products need to be brought to the market

Use of Copper-Based Fungicides in Organic Agriculture in Twelve European Countries

The reduction of copper-based plant-protection products with the final aim of phasing out has a high priority in European policy, as well as in organic agriculture. The aim of this survey was to provide an overview of the current use of these products in European organic agriculture and the need for alternatives to allow policymakers to develop strategies for a complete phasing out. Since there is a lack of centralized databases on pesticide use, we combined expert knowledge on permitted and real copper use per crop and country, with statistics on organic area in 12 European countries covering 83% of the organically managed horticultural area. We calculated that approximately 3258 t copper metal per year is used by organic agriculture in these countries, equalling to 53% of the permitted annual dosage. This amount is split between olives (1263 t y−1, 39%), grapevine (990t y−1, 30%), and almonds (317 t y−1, 10%), followed by other crops with much smaller annual uses (< 80 t y−1). In 56% of the allowed cases (countries × crops), farmers use less than half of the allowed amount, and in 27%, they use less than a quarter. At the time being, completely abandoning copper fungicides would lead to high yield losses in many crops. To successfully reduce or avoid copper use, all preventive strategies have to be fully implemented, breeding programs need to be intensified, and several affordable alternative products need to be brought to the market

Polyacrylamide/poly(2-(dimethylamino) Ethyl Methacrylate) Interpenetrating Polymer Networks as Drug Delivery Systems for Diclofenac Sodium

Nowadays, modern pharmaceutical investigations are directed toward the design and production of drug delivery systems for achieving prolonged and controlled drug delivery. In this respect, the use of interpenetrating polymer networks (IPNs) is an opportunity in the preparation of polymer drug delivery systems with desired characteristics. This paper describes the synthesis and characterization of novel poly(2-(dimethylamino) ethyl methacrylate) (PDMAEMA) and polyacrylamide (PAAm)-based IPNs with different compositions and their application as diclofenac sodium delivery systems. The prepared IPNs were shown to possess phase-separated structures at the nano level, as revealed by SEM and TM-DSC. The IPNs&rsquo; composition was shown to determine the swelling behavior of these novel materials, and the inclusion of the charged IPN component (PDMAEMA) has changed the water molecules type diffusion from Fickian to non-Fickian, as revealed by the swelling kinetics study. Loading efficiency of diclofenac sodium and diclofenac sodium content in the polymer network was evaluated, and in vitro drug release experiments were carried out in order to estimate the ability of the obtained IPNs to control the release of the water-soluble drug

Effect of composition on transcrystallization with reorientation of polypropylene in drawn PET/PP blend

The crystallization behaviour of three blend compositions of poly(ethylene terephthalate)/polypropylene (PET/PP), namely 30/70, 50/50 and 70/30 wt.% was studied. The samples were heated up to temperature between the melting temperatures of the blend components and then cooled to 30 °C. X-ray pictures were taken at every stage and it was shown that a recrystallization with reorientation of the PP crystallites took place during the nonisothermal recrystallization. The PP crystallites in the PET/PP blend reorient with molecular axis tilted at aprox. 49° against the FA during the recrystallization. The amount of PP in the blend does not directly affect the process of trancrystallization with reorientation but has only a masking effect. Such reorientation was observed for all three blends. No reorientation occurs if the PET crystallites have been melted before the recrystallization, i.e., when oriented they induce the reorientation of the PP crystallites

Bioinspired Remineralization of Artificial Caries Lesions Using PDMAEMA/Carbomer/Calcium Phosphates Hybrid Microgels

Dental caries remains one of the most prevalent bacterium-caused chronic diseases affecting both adults and children worldwide. The development of new materials for enhancing its remineralization is one of the most promising approaches in the field of advanced dental materials as well as one of the main challenges in non-invasive dentistry. The aim of the present study is to develop novel hybrid materials based on (PDMAEMA)/Carbomer 940 microgels with in situ deposited calcium phosphates (CaP) and to reveal their potential as a remineralization system for artificial caries lesions. To this purpose, novel PDMAEMA/Carbomer 940 microgels were obtained and their core&ndash;shell structure was revealed by transmission electron microscopy (TEM). They were successfully used as a matrix for in situ calcium phosphate deposition, thus giving rise to novel hybrid microgels. The calcium phosphate phases formed during the deposition process were studied by X-ray diffraction and infrared spectroscopy, however, due to their highly amorphous nature, the nuclear magnetic resonance (NMR) was the method that was able to provide reliable information about the formed inorganic phases. The novel hybrid microgels were used for remineralization of artificial caries lesions in order to prove their ability to initiate their remineralization. The remineralization process was followed by scanning electron microscopy (SEM), X-ray diffraction, infrared and Raman spectroscopies and all these methods confirmed the successful enamel rod remineralization upon the novel hybrid microgel application. Thus, the study confirmed that novel hybrid microgels, which could ensure a constant supply of calcium and phosphate ions, are a viable solution for early caries treatment

Trans-crystallisation with reorientation of polypropylene in drawn PET/PP and PA66/PP blends : part. 1 study with WAXS of synchrotron radiation

Transcrystallisation induced by annealing in the polypropylene (PP) component of nanostructured polymer-polymer composites (NPC) was studied for two different polymeric fillers. In contrast to the typical narrow columnar transcrystalline regions around filler fibres in common glassfibre reinforced PP, volume-filling transcrystallisation was observed for both of the polymer fillers, thus resulting in reorientation of the PP matrix crystals instead of an expected isotropisation. Two colddrawn blends of PP with poly(ethylene terephthalate) (PET) or polyamide 66 (PA66), respectively, namely PET/PP and PA66/PP both in a ratio of 50/50 wt.% were investigated by means of wide-angle X-ray scattering (WAXS) of synchrotron radiation during heating, melting of only the low-melting component (PP) at 200 C yielding an isotropic melt, and subsequent crystallisation upon cooling. A strong epitaxial effect of the persistent embedded microfibrillar component (PET or PA66) on the non-isothermal crystallisation behaviour of PP during its cooling to room temperature was found. The composites obtained after such thermal treatment represented anisotropic semi-crystalline nanocomposites, in which the PP crystallites were reoriented. The ultimate structure for the PET/PP blend exhibited crystals with their molecular axis tilted at approx. 49 with respect to their initial orientation (parallel to the fibre axis). In the PA66/PP blends the ultimate structure returned to the initial orientation of the PP chains parallel to the fibre axis, but with a broadened orientation distribution. Results of similar studies on other blends are reviewed.(undefined

Ammonio Methacrylate Copolymer (Type B)-Diltiazem Interactions in Solid Dispersions and <i>Microsponge</i> Drug-Delivery Systems

This paper presents a complex analytical study on the distribution, solubility, amorphization, and compatibility of diltiazem within the composition of Eudragit RS 100-based particles of microspongeous type. For this purpose, a methodology combining attenuated total reflectance Fourier transform infrared (ATR-FTIR) absorption spectroscopy, differential scanning calorimetry (DSC), scanning electron microscopy with energy-dispersive X-ray microanalysis (SEM-EDX), and in vitro dissolution study is proposed. The correct interpretation of the FTIR and drug-dissolution results was guaranteed by the implementation of two contrasting reference models: physical drug–polymer mixtures and casting-obtained, molecularly dispersed drug–polymer composites (solid dispersions). The spectral behavior of the drug–polymer composites in the carbonyl frequency (νCO) region was used as a quality marker for the degree of their interaction/mutual solubility. A spectral-pattern similarity between the microsponge particles and the solid dispersions indicated the molecular-type dispersion of the former. The comparative drug-desorption study and the qualitative observations over the DSC and SEM-EDX results confirmed the successful synthesis of a homogeneous coamorphous microsponge-type formulation with excellent drug-loading capacity and “controlled” dissolution profile. Among them, the drug-delivery particles with 25% diltiazem content (M-25) were recognized as the most promising, with the highest population of drug molecules in the polymer bulk and the most suitable desorption profile. Furthermore, an economical and effective analytical algorithm was developed for the comprehensive physicochemical characterization of complex delivery systems of this kind