A suitable long-term anaesthetic technique was required for implantation of physiological sensors and telemetric devices in sub-adult Nile crocodiles (Crocodylus niloticus) to allow the collection of physiological data. Five Nile crocodiles with a median body mass of 24 kg were used. After manual capture, they were blindfolded and 0.2 mL (1 mg/mL) medetomidine was administered intramuscularly in four of the animals which had an estimated body mass between 20 kg and 30 kg. One crocodile with an estimated body mass of 50 kg received 0.5 mL. For induction, 5 mL propofol (10 mg/mL) was injected intravenously into the occipital sinus. Additional doses were given when required to ensure adequate anaesthesia. Anaesthesia was maintained with 1.5% isoflurane. Ventilation was controlled. Local anaesthesia was administered for surgical incision and external placement of the radio transmitter. Medetomidine was antagonised with atipamezole at the end of surgery. Median heart rate during surgery was 22 beats/min, at extubation 32 beats per min and 30 beats per min the following day at the same body temperature as under anaesthesia. Median body temperature of the animals increased from 27.3 °C to 27.9 °C during anaesthesia, as room temperature increased from 24.5 °C to 29.0 °C during surgery. Anaesthesia was successfully induced with intramuscular medetomidine and intravenous propofol and was maintained with isoflurane for the placement of telemetric implants. Intraoperative analgesia was supplemented with lidocaine infiltration. Perioperative physiological parameters remained stable and within acceptable clinical limits. Multiple factors appear to influence these variables during the recovery period, including residual anaesthetic effects, environmental temperature and physical activity.

El presente estudio reporta la reactividad de caolinita y metacaolinita en un medio fluorurado bajo condiciones hidrotermales. Esta ruta de síntesis convencional de zeolitas no produjo resultados promisorios, aunque cristalizaron trazas de diferentes zeotipos, como las estructuras cristalinas linde tipo Y (LTY), zeolita NaP1 (GIS), chabazita (CHA), sodalita (SOD), cancrinita (CAN) y linde tipo A (LTA). Otras zeolitas reportadas en este estudio son zeolita ZSM-5 (estructura tipo MFI) y zeolita ITQ (estructura tipo ISV). Los materiales de partida sin reaccionar y los productos sintetizados se caracterizaron por difracción de rayos X, microscopia electrónica de barrido, espectroscopía de infrarrojo por transformada de Fourier y análisis termogravimétrico. Los productos de la síntesis son de interés, ya que pueden utilizarse en diversas aplicaciones industriales.

This paper studies the reactivity of kaolinite and metakaolin in a fluori-nated medium under hydrothermal conditions. This path of conventional zeolite synthesis did not yield promising results, although traces of different zeotypes did crystallize, such as the crystal structures Linde type Y (LTY), zeolite Na-P1 (GIS), chabazite-ca (CHA), sodalite (SOD), cancrinite (CAN) and Linde type A (LTA). Other zeolites reported in this study were zeolite ZSM-5 (MFI type structure) and zeolite ITQ (ISV type structure). The non-reacting starting material and the synthesized products where characterized by x-ray diffraction, scanning electron microscopy, infrared spectroscopy by Fourier transform and thermogravimetric analysis. The products of the synthesis are of interest because they can be used in different industrial applications.

Este estudo relata a reatividade de caulinita e metacaulinita em um meio fluoretado em condições hidrotermais. Essa rota de síntese convencional de zeólitas não produziu resultados promissores, embora os traços de diferentes zeótipos tenham se cristalizado, como as estruturas cristalinas linde tipo Y (LTY), zeólita Na-P1 (GIS), chabazita (CHA), sodalita (SOD), cancrinita (CAN) e linde tipo A (LTA). Outras zeólitas relatadas neste estudo são zeólita ZSM-5 (estrutura tipo MFI) e zeólita ITQ (estrutura tipo ISV). Os materiais de partida sem reação e os produtos sintetizados caracterizaram-se pela difração de raios X, microscopia eletrônica de varredura, espectroscopia de infravermelho por transformada de Fourier e análise termogravimétrica. Os produtos da síntese são de interesse já que podem ser utilizados em diversas aplicações industriais.

The synthesis of low-silica zeotypes by hydrothermal transformation of kaolinite-rich clay and the nucleation and growth processes of sodalite and cancrinite in the system Na2O-Al2O3-SiO2-H2O at 100 °C were investigated. The synthesis products were characterized by X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), 29Si and 27Al Magic Angle Spinning Nuclear Magnetic Resonance (MAS-NMR) and thermogravimetric analysis (TGA). Our data show that the sequence of the transformation of phases is: Poorly crystalline aluminosilicate → zeolite LTA → sodalite → sodalite + cancrinite → cancrinite. Synthesized materials appeared stable thermodynamically under the experimental conditions, with zeolite LTA (a metastable phase) occurring as a minor phase, compared with the presence of sodalite and cancrinite.

En el presente estudio se llevó a cabo la síntesis de zeolitas Na-A y Na-X a partir de caolín y obsidiana, respectivamente, siguiendo el método de fusión alcalina. Los materiales de partida fueron activados hidrotérmicamente con NaOH para sintetizar productos de alta pureza. La transformación de los materiales de partida en zeolitas ha sido evaluada por técnicas de difracción de rayos X de polvo, microscopia electrónica de barrido y espectroscopia de infrarrojo por transformada de Fourier para dilucidar el proceso de cristalización de zeolitas. El uso de materiales de bajo coste en la síntesis de zeolitas se ha convertido en un área de gran interés e investigación, desempeñando un papel activo en la promoción de los avances tecnológicos, la investigación y transferencia de tecnología relacionados con la producción de materiales zeolíticos en condiciones experimentales controladas

Zeolites Na-A and Na-X were successfully synthesized from kaolin and obsidian, respectively, following the alkaline fusion method. Raw materials were hydrothermally activated with NaOH to synthesize zeolites Na-A and Na-X. The transformation of the starting materials into zeolites has been evaluated by powder X-ray diffraction, scanning electron microscopy and Fourier transformed infrared spectroscopy to elucidate the crystallization process of zeolites. The use of low cost materials in zeolite synthesis become an area of important interest and research, playing an active role in promoting technological advances, research and technology transfer related to the production of zeolytic materials under well-optimized experimental conditions

Las zeolitas naturales como relleno en amígdalas y venas que ocurren en rocas basálticas Terciarias de la Isla de Skye (NW Escocia) han sido estudiadas en detalle por técnicas de microscopía de luz transmitida, microscopía electrónica de barrido y difracción de rayos X. Las zeolitas y los minerales asociados identificados, en orden de su tiempo relativo de formación, son nontronita, fases de sílice amorfa, carbonatos, chabazita, filipsita, wairakita, thomsonita, analcima, natrolita y minerales tipo estilbita. La formación de zeolitas en los basaltos de Skye comenzó con una zeolita rica en Na de baja relación Si/Al y con el aumento gradual en el contenido de Ca y Si/Al, terminó con una zeolita rica en Ca Estas probablemente se formaron como consecuencia de una actividad hidrotermal tardía, aunque localmente un metamorfismo de contacto pudo controlar el proceso de formación de las zeolitas

Natural zeolites filling amygdales and veins in tertiary basaltic host rocks on the Isle of Skye (NW Scotland) have been studied in some detail by transmitted light microscopy, scanning electron microscopy and X-ray diffraction techniques. The zeolites and associated minerals so identified in order of their relative time of formation from early to late were nontronite, amorphous silica phases, carbonate phases, chabazite, phillipsite, wairakite, thomsonite, analcime, natrolite and stilbite-type minerals. Zeolite formation in the Skye basalts began with low Si/Al ratio Na zeolites and a gradual increase in Ca content and Si/Al ratio, ending up as Ca zeolites. They were probably formed as a consequence of late-stage hydrothermal activity, although, locally, contact metamorphism may control the process of zeolite formation

Materiales zeolíticos bajos en sílice como SOD, CAN y JBW cristalizaron después de la reacción hidrotérmica de caolinita en el sistema Na2O-Al2O3-SiO2-H2O a 200°C, con o sin adición de un agente director de estructura. Los productos de la síntesis fueron caracterizados por DRX, MEB, espectroscopía FTIR, 29Si- y 27Al-RMN y TGA. Después de la disolución de la caolinita en medio alcalino, co-cristalizaron SOD y CAN, probablemente a partir de una fase intermedia metastable (LTA), lo cual fue seguido por una transformación a la estructura tipo JBW.

Low-silica zeolitic materials like SOD, CAN and JBW crystallized after hydrothermal transformation of kaolinite in the system Na2O-Al2O3-SiO2-H2O at 200°C, with or without the addition of a structure-directing agent. The synthesis products were characterized by XRD, SEM, FTIR, 29Si and 27Al MAS-NMR and TGA. After dissolution of kaolinite in alkaline medium, co-crystallization of SOD and CAN, likely via a metastable LTA intermediate, was followed by a transformation to JBW-type structure.

Una materia prima rica en caolinita fue tratada hidrotérmicamente con soluciones de KOH 1.33 y 3.99M a 100 y 175 °C durante diferentes tiempos de reacción variando de 24 a 528 h. Los productos sintéticos fueron caracterizados por difracción de rayos X, microscopia electrónica de barrido, espectroscopia infrarrojo por transformada de Fourier, resonancia magnética nuclear con rotación en ángulo mágico y análisis termogravimétrico con el fin de establecer sus características fisicoquímicas y mineralógicas. La transformación del material de partida en soluciones de KOH pueden explicarse a partir de dos procesos diferentes: (1) disolución y (2) precipitación. Una serie de fases cristalinas resumidas por la secuencia de reacción caolinita ® chabazita ® edingtonita ® fase de aluminosilicato potásico no identificada ® kalsilita + leucita fue identificada en el sistema K2O-SiO2-Al2O3-H2O. Los productos sólidos, muestran, por otra parte, notables diferencias texturales y estructurales con el material de partida.

A kaolinite-rich raw material was treated hydrothermally with 1.33 and 3.99M KOH solutions at 100 and 175 °C during different reaction times ranging from 24 to 528 h. The synthesis products were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, magic angle spinning nuclear magnetic resonance and thermogravimetric analysis in order to elucidate their physicochemical and mineralogical characteristics. The transformation of the starting material in KOH solutions can be explained by two different processes: (1) dissolution and (2) precipitation. A series of crystalline phases summarized by the reaction sequence kaolinite ® chabazite ® edingtonite ® unidentified potassium aluminosilicate phase ® kalsilite + leucite was identified in the system K2O-SiO2-Al2O3-H2O. The solid products show, on the other hand, remarkable textural and structural differences with the starting material.

La síntesis de zeolita LTA y fases asociadas a partir de metacaolinita se evaluaron mediante análisis de difracción de rayos X, microscopía electrónica de barrido, espectroscopia de infrarrojo por transformada de Fourier, resonancia magnética nuclear de 29Si y 27Al y análisis termogravimétrico. Sin embargo, el producto sintetizado fue controlado por el método experimental, teniendo en cuenta que la transformación hidrotérmica del material de partida por el método clásico produjo una mezcla de diferentes estructuras tipo zeolita, mientras que la aproximación por el método de fusión alcalina promovió la cristalización de zeolita LTA pura.

X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, 29Si and 27Al nuclear magnetic resonance and thermogravimetric analyses have been used to examine the synthesis of zeolite LTA and associated phases from metakaolinite. However, the synthesis product was controlled by the experimental method, taking into account that the classic hydrothermal transformation of the starting material produced a mixture of different zeolite-type structures, whereas the alkaline fusion approach promoted the crystallization of pure zeolite LTA.