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The encapsulation and delivery of drugs often involves the use of expensive microporous materials, and we have investigated the potential for natural zeolites from the widespread volcanic formations of southern Italy as alternatives to these carriers. Surface-modified natural zeolites (SMNZs) with diverse micellar structures (patchy and complete bilayers) were obtained by using different cationic surfactants [cetylpyridinium chloride (CP-Cl), benzalkonium chloride (BC-Cl), hexadecyltrimethylammonium chloride (HDTMA-Cl), and bromide (HDTMA-Br) with phillipsite-rich tuff from the Campania region (southern Italy)]. Loading and release kinetics tests of sodium ibuprofen (IBU) were carried out with organo-phillipsite composites using Fourier transform infrared spectroscopy (FTIR) and thermal analysis coupled with evolved gas analysis (EGA). Results from these tests were mathematically modeled to evaluate IBU adsorption and release mechanisms. The maximum loaded amount of IBU was attained for organo-phillipsite modified with HDTMABr (PHB), which showed a complete bilayer micellar structure. Whenever a patchy bilayer micellar structure formed, the lowest adsorptions of IBU were observed. Equilibrium adsorption results were fit using Langmuir, Sips, and Toth models. Pseudo-first-order and pseudo-second-order fits to the loading kinetic data provided significant goodness of fit. Good fits to the release kinetic data were obtained using first-order and Weibull equations, shedding new light on the release mechanism of IBU from phillipsite. The active amount of IBU on the modified zeolite surface was almost totally available for pharmaceutical purposes.

The principal function of skin is to form an effective barrier between the human body and its environment. Impaired barrier function represents a precondition for the development of skin diseases such as atopic dermatitis (AD), which is the most common inflammatory skin disease characterized by skin barrier dysfunction. AD significantly affects patients’ quality of life, thus, there is a growing interest in the development of novel delivery systems that would improve therapeutic outcomes. Herein, eight novel lyotropic liquid crystals (LCCs) were investigated for the first time in a double-blind, interventional, before-after, single-group trial with healthy adult subjects and a twice-daily application regimen. LCCs consisted of constituents with skin regenerative properties and exhibited lamellar micro-structure, especially suitable for dermal application. The short- and long-term effects of LCCs on TEWL, SC hydration, erythema index, melanin index, and tolerability were determined and compared with baseline. LCCs with the highest oil content and lecithin/Tween 80 mixture stood out by providing a remarkable 2-fold reduction in TEWL values and showing the most distinctive decrease in skin erythema levels in both the short- and long-term exposure. Therefore, they exhibit great potential for clinical use as novel delivery systems for AD treatment, capable of repairing skin barrier function.

Fibrous erionite is classified by the International Agency for Research on Cancer (IARC) as carcinogenic substance to humans (Group 1). In the areas where it is present in the bedrock, it may cause environmental exposure, and both professional and environmental exposures are possible when the bedrock is used for industrial applications (e.g., building materials). For health and environment protection, prevention is a priority action. In this framework, the recent guidelines of the Consensus Report of the Weinman International Conference on Mesothelioma suggest identifying locations where potentially hazardous mineral fibers (like erionite) are found in the environment, to prevent environmental exposure. The present study will show that one such potentially hazardous mineral fiber might be fibrous ferrierite. Here, the mineralogy, chemical-physical properties, and surface activity of a hydrothermal fibrous ferrierite from Monte Lake British Columbia (Canada) and a diagenetic fibrous ferrierite from Lovelock, Nevada (U.S.A.), were investigated using a combination of \"state of the art\" experimental methods including optical microscopy, electron microscopy and microprobe analysis, laser ablation-inductively coupled plasma-mass spectrometry (for the trace elements), vibrational spectroscopy, electron paramagnetic resonance, and synchrotron powder diffraction. The chemical-physical properties of these fibrous ferrierites (morphometric parameters, specific surface area, chemical composition with special attention to metals, mainly iron) that prompted adverse effects in vivo were compared to those of the positive carcinogenic standard fibrous erionite-Na from Jersey, Nevada (U.S.A.). The results of our study have demonstrated that, although there are differences in the crystal chemistry and genetic environment, ferrierite samples exhibit outstanding similarities with fibrous erionite samples: both fibrous erionite and fibrous ferrierite may occur in large amounts as microcrystalline fibrous-asbestiform phases in diagenetic rocks with fibers of breathable sizes. For both zeolites, iron is not structural but is associated with impurities lying at the surface of the fibers. Moreover, data useful to understand the surface activity of these fibrous ferrierites were collected. As far as hydrothermal sample is concerned, the EPR data indicate the presence of hydrophilic (SiO-, AlO-, SiOH) and hydrophobic (Si-O-Si) interacting surface groups able to bind the charged CAT1 probes at close sites and attract the probes in the water pools formed into the fiber aggregates. A high percentage of CAT1 probes weakly interacting with the surface due to competition with metal ions were observed for surface of the diagenetic sample. CAT8 probes were less adsorbed by its surface if compared to the diagenetic sample but the more charged surface provided a stronger binding strength for the diagenetic sample compared to the hydrothermal one. In summary, the results of this study indicate that fibrous ferrierite may represent a potential health hazard and, applying the precautionary principle, it should undergo a procedure of toxicity testing.

The relationships between synthetic zeolites and their natural counterparts that have been unveiled by theoretical studies have contributed to improving the properties and applications of zeolite-based materials in strategic areas such as industrial catalysis, environmental protection, and solar energy harvesting. To pinpoint the role of modeling in zeolite science, we discuss an example of computationally driven problem solving: can tetrahedral frameworks sustain straight (i.e., 180°) Si-O-Si bond angles? The true crystal symmetry of zeolite ferrierite (FER), especially in its all-silica form, had been intensely debated for 30 years before being solved in the Pmnn space group. Yet there are indications that an Immm structure with energetically unfavorable linear Si-O-Si linkages could be formed at high temperature. To gather insight, we perform density functional theory (DFT) optimizations and frequency calculations of all-silica ferrierite in both the Pmnn and Immm space groups. Our results indicate that Pmnn is more stable than Immm, in line with experiments. While the Pmnn structure is a true minimum in the energy profile of ferrierite, the Immm structure has four imaginary frequency vibrations, three of which are localized on the 180° Si-O-Si angles. This suggests that ferrierites with Immm symmetry may be classified as metastable phases. Such a designation is also supported by first-principles molecular dynamics on Immm FER, showing that the average value of 180° actually results from Si-O-Si angle inversion. An implication of this study with interesting geological and technological consequences is the association of straight Si-O-Si angles experimentally detected in open-framework or low-density silicates to an angle-inversion process occurring at the femtosecond scale. Such flexibility of the apparently flat Si-O-Si linkages might play an important role in sorption phenomena, which are ubiquitous in geological processes and industrial applications alike.

Determination of the oxidation state and coordination geometry of iron in Fe-bearing minerals expands our knowledge obtained by standard mineralogical characterization. It provides information that is crucial in assessing the potential of minerals to interact with their surrounding environment and to generate reactive oxygen species, which can disrupt the normal function of living organisms. Aberration-corrected scanning transmission electron microscopy dual-electron energy-loss spectroscopy (acSTEM Dual-EELS) has only rarely been applied in environmental and medical mineralogy, but it can yield data that are essential for the description of near-surface and surface mechanisms involved in many environmental and health-related processes. In this study, we have applied the energy loss near-edge structure (ELNES) and L2,3 white-line intensity-ratio methods using both the universal curve and progressively larger integrating windows to verify their effectiveness in satisfactorily describing the valence state of iron at amosite grain boundaries, and, at the same time, to estimate thickness in the same region of interest. The average valence state obtained from acSTEM Dual-EELS and from a simplified geometrical model were in good agreement, and within the range defined by the bulk and the measured surface-valence states. In the specific case presented here, the use of the universal curve was most suitable in defining the valence state of iron at amosite grain boundaries. The study of ELNES revealed an excellent correspondence with the valence state determined by the L2,3 white-line intensity-ratio method through the use of the universal curve, and it seems that the spectra carry some information regarding the coordination geometry of Fe. The combination of visual examination, reconstruction of the grain boundaries through a simple geometrical model, and Dual-EELS investigation is a powerful tool for characterizing the grain boundaries of hazardous minerals and foreseeing their potential activity in an organism, with the possibility to describe toxic mechanisms in a stepwise fashion.

Nepheline crystallizes upon slow-cooling in some melts concentrated in Na2O and Al2O3, which can result in a residual glass phase of low chemical durability. Nepheline can incorporate many components often found in high-level waste radioactive borosilicate glass, including glass network ions (e.g., Si, Al, Fe), alkali metals (e.g., Cs, K, Na, and possibly Li), alkaline-earth metals (e.g., Ba, Sr, Ca, Mg), and transition metals (e.g., Mn, and possibly Cr, Zn, Ni). When crystallized from melts of different compositions, nepheline composition varies as a function of starting melt composition. Five simulated high-level nuclear waste borosilicate glasses shown to crystallize large fractions of nepheline on slow-cooling were selected for study. These starting melt compositions contained a range of Al2O3, B2O3, CaO, Na2O, K2O, Fe2O3, and SiO2 concentrations. Compositional analyses of nepheline crystals in glass by electron probe micro-analysis (EPMA) indicate that nepheline is generally rich in silica, whereas boron is unlikely to be present in any significant concentration, if at all, in nepheline. Also, several models are presented for calculating the fraction of vacancies in the nepheline structure.

In situ high-pressure single-crystal X-ray diffraction studies of mesolite, an aluminosilicate composed of stacks of Na+-containing natrolite and Ca2+-containing scolecite layers in the ratio of 1:2, showed two discrete steps of pressure-induced hydration (PIH): first H2O molecules are inserted into the natrolite layers between ∼0.5 and ∼1.5 GPa and subsequently into the scolecite layers. During the PIH in the natrolite layers, the coordination environment of Na+ changes from six to seven, the same as that of Ca2+ in the scolecite layers. While the natrolite layers behave as in the mineral natrolite, the scolecite layers show a different behavior from the mineral scolecite by adopting the super-hydrated natrolite-type structure at higher pressure, as a larger distortion is not favorable in the 1:2 layered framework. This spatial separation of inserted H2O during PIH and the growing structural similarity of the two layers result in a weakening of k ≠ 3n reflections maintaining the 1:2 layer configuration. Our study of this unique behavior of mesolite provides a simple model of structuration under pressure, and the implications of our experimental findings are discussed.

In this paper, we report the results of the first study focused on the thermal stability and dehydration dynamics of the natural zeolite mineral ferrierite. A sample from Monastir, Sardinia [(Na0.56K1.19Mg2.02Ca0.52Sr0.14) (Al6.89Si29.04)O72·17.86H2O; a = 19.2241(3) Å; b = 14.1563(2) Å; c = 7.5106(1) Å, V = 2043.95(7) Å3] was investigated by thermogravimetric analysis and in-situ synchrotron X-ray powder diffraction. Thermogravimetric data show that H2O release begins already in the range 50-100 °C and is complete at ∼600 °C. The results of the structure refinements performed in Immm space group by Rietveld analysis with data collected up to 670 °C show that ferrierite belongs to the group of zeolites that do not undergo phase transitions. Upon heating to 670 °C, ferrierite behaves as a non-collapsible structure displaying only a slight contraction of the unit-cell volume (ΔV = -3%). The unit-cell parameter reductions are anisotropic, more pronounced for a than for b and c (Δa = -1.6%; Δb = -0.76%; Δc = -0.70%). This anisotropic response to a temperature increase is interpreted as due to the presence in the ferrierite framework of five-membered ring chains of SiO4 tetrahedra, which impart a higher structural rigidity along b and c. Upon dehydration we observe: (1) the gradual H2O loss, beginning with the molecules hosted in the 10MR channel, is almost complete at 670 °C, in good agreement with the TG data; (2) as a consequence of the decreased H2O content, Mg and K migrate from their original positions, moving from the center of the 10MR channel toward the walls to coordinate the framework oxygen atoms. The observation of transmission electron microscopy selected-area electron diffraction patterns revealed defective crystals with an occasional and moderate structural disorder. Beyond providing information on the thermal stability and behavior of natural ferrierite, the results of this work have significant implications for possible technological applications. These data allow for comparison with the dehydration kinetics/mechanisms of the corresponding synthetic phases, clarifying the role played by framework and extra-framework species on the high-temperature behavior of porous materials with ferrierite topology. Moreover, the information on the thermal behavior of natural ferrierite can be used to predict the energetic performances of analogous synthetic Si-pure counterparts, namely \"zeosil-electrolyte\" systems, under non-ambient conditions. Specifically, the very high thermal stability of ferrierite determined in this study, coupled with the baric behavior determined in other investigations, suggests that the \"Si-FER-electrolyte\" system may be an excellent candidate for use as an energy reservoir. Indeed, ferrierite exhibits the so-called \"spring behavior,\" i.e., upon compression in water or in an electrolyte solution, it converts the mechanical energy into interfacial energy, and-when pressure is released-it can completely restore the supplied mechanical energy accumulated during the compression step.

Subvolcanic phonolite intrusions of the Kaiserstuhl Volcanic Complex (Germany) show variable degrees of alteration. Their secondary mineralogy has been characterized by petrographic textural observations, bulk-rock powder X-ray diffraction, thermogravimetry, differential thermal analysis, and electron probe microanalysis. The alteration assemblage is dominated by various zeolites that occur in fissures, vugs, and as replacement products of primary phases within the phonolite matrix. Phonolites in the eastern Kaiserstuhl were emplaced into a sedimentary sequence and are characterized by high zeolite contents (Endhalden: 48 wt%, Fohberg: 45 wt%) with the temporal sequence: ± thomsonite-Ca ± mesolite - gonnardite - natrolite - analcime. In the western Kaiserstuhl zeolite contents are lower (Kirchberg: 26 wt% or less) and the crystallization sequence is: ± thomsonite-Ca - gonnardite - natrolite - chabazite-Ca. Pseudomorphic replacement textures and barite inclusions in secondary aggregates suggest that zeolites grew at the expense of a sulfate-bearing sodalite-group mineral, i.e., hauyne. Fresh grains of sodalite-hauyne are only found at Kirchberg, whereas the pervasive alteration at Fohberg and Endhalden transformed feldspathoid minerals completely to zeolites. Zeolites formed in a continuously cooling hydrothermal regime after emplacement and solidification of phonolitic magmas. The common paragenetic sequence corresponds to a decrease in the Ca/Na ratio, as well as an increase in the Si/Al ratio with time. The shift from Ca-Na- to pure Na-zeolites is an expression of closed-system behavior in a water-rich environment at Fohberg and Endhalden, which both intruded an Oligocene pre-volcanic sedimentary unit. The late crystallization of K-bearing chabazite-Ca points to a progressively more open hydrothermal system in the Kirchberg phonolite, which was emplaced in a subaerial volcanic succession and was influenced by K-enriched fluid from leucite-bearing country rock. Therefore, the geological setting and nature of emplacement are important factors that control the degree of zeolitization of intrusive feldspathoid minerals-bearing rocks and whether a zeolite occurrence can be used as mineral deposit.

Chloroacetanilides and their degradation products are frequently detected in surface and subsurface water due to their relatively high water solubility and their high potential to leach and migrate through the soil and contaminate groundwater. In this study, we explored for the first time the capability of ZSM-12 zeolite for 2-ethyl-6-methyl-aniline [C2H5C6H3(CH3)NH2, labeled EMA] removal from water by combining chromatographic, thermogravimetric, and synchrotron X-ray powder diffractometric techniques. Rietveld refinement revealed the incorporation of about 4 EMA molecules per unit cell, in very good agreement with the weight loss given by TG analyses and with the saturation capacity determined by the adsorption isotherms. The formation of supramolecular complexes mediated by co-adsorbed water and their strong interaction to framework O atoms confers stability to the pollutants in the zeolite cages. This prevents adsorbed molecules from desorbing as well as the entering of other competitive molecules. The rapid kinetics combined with the good adsorption capacity makes ZSM-12 a promising material to control and minimize water pollution from acetanilide compounds as well as other agro-chemicals contaminants.