Synthesis and Raman spectroscopic study of Mg/Al,Fe hydrotalcites with variable cationic ratios

Hydrotalcites of formula Mg₆(Al,Fe)₂(OH)₁₆(CO₃)·4H₂O formed by intercalation with the carbonate anion as a function of divalent/trivalent cationic ratio have been successfully synthesised. The XRD patterns show variation in the d‐spacing attributed to the size of the cation. Raman and infrared bands in the OH stretching region are assigned to (1) brucite layer OH stretching vibrations, (2) water stretching bands and (3) water strongly hydrogen bonded to the carbonate anion. Multiple (CO₃)²⁻ symmetric stretching bands suggest that different types of (CO₃)²⁻ exist in the hydrotalcite interlayer. Increasing the cation ratio (Mg/Al,Fe) resulted in an increase in the combined intensity of the two Raman bands at around 3600 cm⁻¹, attributed to Mg OH stretching modes, and a shift of the overall band profile to higher wavenumbers. These observations are believed to be a result of the increase in magnesium in the structure. Raman spectroscopy shows a reduction in the symmetry of the carbonate, leading to the conclusion that the anions are bonded to the brucite‐like hydroxyl surface and to the water in the interlayer. Water bending modes are identified in the infrared spectra at positions greater than 1630 cm⁻¹, indicating that water is strongly hydrogen bonded to both interlayer anions and the brucite‐like surface. Copyright © 2009 John Wiley & Sons, Ltd.     

Rapid initiation of reactions in Al/Ni multilayers with nanoscale layering

Research into nanoenergetic materials is enabling new capabilities for controlling exothermic reaction rates and energy output, as well as new methods for integrating these materials with conventional electronics fabrication techniques. Many reactions produce primarily heat, and in some cases it is desirable to increase the rate of heat release beyond what is typically observed. Here we investigate the Al-Ni intermetallic reaction, which normally propagates across films or foils at rates lower than 10 m/s. However, models and experiments indicate that local heating rates can be very high (10⁷ K/s), and uniform heating of such a multilayer film can lead to a rapid, thermally explosive type of reaction. With the hopes of using a device to transduce electrical energy to kinetic energy of a flyer plate in the timescale of 100's of nanoseconds, we have incorporated a Ni/Al nanolayer film that locally heats upon application of a large electrical current. We observed flyer plate velocities in the 2-6 km/s range, corresponding to 4-36 kJ/g in terms of specific kinetic energy. Several samples containing Ni/Al films with different bilayer thicknesses were tested, and many produced additional kinetic energy in the 1.1-2.3 kJ/g range, as would be expected from the Ni-Al intermetallic reaction. These results provide evidence that nanoscale Ni/Al layers reacted in the timescale necessary to contribute to device output.     

Gels and glasses in a single system: evidence for an intricate free-energy landscape of glassy materials

In the free-energy landscape picture of glassy systems, their slow dynamics is due to a complicated free-energy landscape with many local minima. We show that for a colloidal glassy material multiple paths can be taken through the free-energy landscape. The evolution of the nonergodicity parameter shows two distinct master curves that we identify as gels and glasses. We show that for a range of colloid concentrations, the transition to nonergodicity can occur in either direction (gel or glass), accompanied by "hesitations" between the two. Thus, colloidal gels and glasses are merely global free-energy minima in the same free-energy landscape, and the paths leading to these minima can be complicated.     

Pharmacokinetic Characterization of the DDAH1 Inhibitors ZST316 and ZST152 in Mice Using a HPLC-MS/MS Method

The pharmacokinetic profile of ZST316 and ZST152, arginine analogues with inhibitory activity towards human dimethylarginine dimethylaminohydrolase-1 (DDAH1), was investigated in mice using a newly developed HPLC-MS/MS method. The method proved to be reproducible, precise, and accurate for the measurement of the compounds in plasma and urine. Four-week-old female FVB mice received a single dose of ZST316 and ZST152 by intravenous bolus (30 mg/Kg) and oral gavage (60 mg/Kg). ZST316 Cmax was 67.4 µg/mL (intravenous) and 1.02 µg/mL (oral), with a half-life of 6 h and bioavailability of 4.7%. ZST152 Cmax was 24.9 µg/mL (intravenous) and 1.65 µg/mL (oral), with a half-life of 1.2 h and bioavailability of 33.3%. Urinary excretion of ZST152 and ZST316 was 12.5%–22.2% and 2.3%–7.5%, respectively. At least eight urinary metabolites were identified. After chronic intraperitoneal treatment with the more potent DDAH1 inhibitor, ZST316 (30 mg/Kg/day for three weeks), the bioavailability was 59% and no accumulation was observed. Treatment was well tolerated with no changes in body weight vs. untreated animals and no clinical signs of toxicity or distress. The results of this study show that ZST316 has a favorable pharmacokinetic profile, following intraperitoneal administration, to investigate the effects of DDAH1 inhibition in mice.     

Chemical Composition and Evaluation of Insecticidal Activity of Calendula incana subsp. maritima and Laserpitium siler subsp. siculum Essential Oils against Stored Products Pests

The problems of the environment and human health related to the use of synthetic and broad-spectrum insecticides have increasingly motivated scientific research on different alternatives and among these, the use of green systems, such as essential oils, have been explored. Several species of the Apiaceae and Asteraceae families, aromatic herbs rich in secondary bioactive metabolites, are used in the industrial field for pharmaceutical, cosmetic, and food purposes. Different essential oils extracted from some species of these families have shown acute toxicity and attractive and/or repellent effects towards different insects. In our work, we investigated the toxic potential of Calendula incana subsp. maritima and Laserpitium siler subsp. siculum essential oils against four insect species, Sitophilus oryzae, Lasioderma serricorne, Necrobia rufipes, and Rhyzoperta dominica, which are common pests of stored products. The composition of both oils, extracted by hydrodistillation from the aerial parts of the two plants, was evaluated by GC×GC-MS. Calendula incana subsp. maritima essential oil was rich in oxygenated sesquiterpenoids, such as cubebol (35.39%), 4-epi-cubebol (22.99%), and cubenol (12.77%), while the Laserpitium siler subsp. siculum essential oil was composed mainly of monoterpene hydrocarbons, such as β-phellandrene (42.16%), limonene (23.87%), and β-terpinene (11.80%). The toxicity Petri dish bioassays indicated that C. maritima oil killed a mean of 65.50% of S. oryzae and 44.00% of R. dominica adults, indicating a higher biocidal activity in comparison with L. siculum oil, while toward the other species, no significant differences in mortality were recorded. Calendula maritima oil could be, then, considered a promising candidate for further tests as an alternative biocide toward S. oryzae and R. dominica. The possibility that the relatively high content of oxygenated sesquiterpenoids in C. maritima essential oil determines its higher biocidal activity is discussed.     

The Current State of Knowledge on Salvia hispanica and Salviae hispanicae semen (Chia Seeds)

Chia seeds (Salviae hispanicae semen) are obtained from Salvia hispanica L. This raw material is distinguished by its rich chemical composition and valuable nutritional properties. It is currently referred to as “health food”. The purpose of the present work was to perform a literature review on S. hispanica and chia seeds, focusing on their chemical composition, biological properties, dietary importance, and medicinal uses. The valuable biological properties of chia seeds are related to their rich chemical composition, with particularly high content of polyunsaturated fatty acids, essential amino acids, polyphenols, as well as vitamins and bioelements. The available scientific literature indicates the cardioprotective, hypotensive, antidiabetic, and antiatherosclerotic effects of this raw material. In addition, studies based on in vitro assays and animal and human models have proven that chia seeds are characterized by neuroprotective, hepatoprotective, anti-inflammatory, and antioxidant properties. These properties indicate a valuable role of chia in the prevention of civilization diseases. Chia seeds are increasingly popular in functional food and cosmetic and pharmaceutical industries. That is attributed not only to their desirable chemical composition and biological activity but also to their high availability. Nevertheless, S. hispanica is also the object of specific biotechnological studies aimed at elaboration of micropropagation protocols of this plant species.     

Sustainability in Skin Care: Incorporation of Avocado Peel Extracts in Topical Formulations

The avocado peel is an agro-industrial by-product that has exhibited a massive increase in its production in the last few years. The reuse and valorisation of this by-product are essential since its disposal raises environmental concerns. In the present study, ethanolic extracts of avocado peels of the Hass variety were obtained, for three extraction times (1.5 h, 3 h and 4 h) and analysed for their antioxidant and antibacterial properties. Antioxidant evaluations of the extracts revealed that the extraction time of 1.5 h exhibited the best results amongst the three, with a DPPH inhibition percentage of 93.92 ± 1.29 and an IC₅₀ percentage, the necessary concentration of the extract to inhibit 50% of DPPH, of 37.30 ± 1.00. The antibacterial capacity of the extracts was evaluated and it was revealed that they were able to inhibit the growth and development of bacteria of the Staphylococcus family. The obtained extract was incorporated in two types of cosmetic formulations (oil-in-water and water-in-oil) and their stability was evaluated and compared with formulations containing synthetic preservatives (BHT and phenoxyethanol). The results of the stability evaluation suggest that the avocado peel extract has the potential to be incorporated in both types of emulsions, acting as an antioxidant and antibacterial agent, proving it to be a viable option to reduce/replace the use of synthetic preservatives. Furthermore, the avocado peel extract proved to be more effective and stable in oil-in-water emulsions. These results highlight the possibility of obtaining sustainable cosmetics, significantly reducing the negative impacts on the environment by the incorporation of extracts sourced from the avocado peel, an interesting source of phenolic compounds, an abundant and low-cost by-product.     

Sum-rules of the response potential in the strongly-interacting limit of DFT

The response part of the exchange-correlation potential of Kohn–Sham density functional theory plays a very important role, for example for the calculation of accurate band gaps and excitation energies. Here we analyze this part of the potential in the limit of infinite interaction in density functional theory, showing that in the one-dimensional case it satisfies a very simple sum rule.     

Acoustic energy relations in Mudejar-Gothic churches

Extensive objective energy-based parameters have been measured in 12 Mudejar-Gothic churches in the south of Spain. Measurements took place in unoccupied churches according to the ISO-3382 standard. Monoaural objective measures in the 125-4000 Hz frequency range and in their spatial distributions were obtained. Acoustic parameters: clarity C80, definition D50, sound strength G and center time Ts have been deduced using impulse response analysis through a maximum length sequence measurement system in each church. These parameters spectrally averaged according to the most extended criteria in auditoria in order to consider acoustic quality were studied as a function of source-receiver distance. The experimental results were compared with predictions given by classical and other existing theoretical models proposed for concert halls and churches. An analytical semi-empirical model based on the measured values of the C80 parameter is proposed in this work for these spaces. The good agreement between predicted values and experimental data for definition, sound strength, and center time in the churches analyzed shows that the model can be used for design predictions and other purposes with reasonable accuracy.     

Infinitely many solutions of a symmetric semilinear elliptic equation on an unbounded domain

We study a semilinear elliptic equation of the form