Spectroscopic Studies of Synthetic and Natural Saponites: A Review

Saponite is a trioctahedral 2:1 smectite with the ideal composition MxMg3AlxSi4−xO10(OH,F)2.nH2O (M = interlayer cation). Both the success of the saponite synthesis and the determination of its applications depends on robust knowledge of the structure and composition of saponite. Among the routine characterization techniques, spectroscopic methods are the most common. This review, thus, provides an overview of various spectroscopic methods to characterize natural and synthetic saponites with focus on the extensive work by one of the authors (JTK). The Infrared (IR) and Raman spectra of natural and synthetic saponites are discussed in detail including the assignment of the observed bands. The crystallization of saponite is discussed based on the changes in the IR and Raman spectra and a possible crystallization model is provided. Infrared emission spectroscopy has been used to study the thermal changes of saponite in situ including the dehydration and (partial) dehydroxylation up to 750 °C. 27Al and 29Si magic-angle-spinning nuclear magnetic resonance spectroscopy is discussed (as well as 11B and 71Ga for B- and Ga-Si substitution) with respect to, in particular, Al(IV)/Al(VI) and Si/Al(IV) ratios. X-ray photoelectron spectroscopy provides chemical information as well as some information related to the local environments of the different elements in the saponite structure as reflected by their binding energies

X-ray Photoelectron Spectroscopic Study of Some Organic and Inorganic Modified Clay Minerals

Layered clay systems intercalated with inorganic and organic compounds were analyzed to highlight how XPS can provide information on the different environments surrounding a particular atom as well as provide discernments on the size, coordination, and structural and oxidative transformations of the intercalating/pillaring compounds. XPS data on the intercalation of urea and K-acetate in low- and high-defect kaolinite revealed the interaction of the intercalating group NH2 with the siloxane functional groups in the interlayer surface. The intercalation of HDTMA in Mt demonstrated the use of XPS in monitoring the change in conformation assumed by alkylammonium intercalating compounds in Mt with increasing CEC. Studies on the pillaring of Mt by Al13 and Ga13 by XPS allowed determination of the coordination of the pillaring compound within the Mt layer. Lastly, the intercalation of hexacyanoferrate in hydrotalcite demonstrated the capability of XPS in following changes in the oxidation state of the iron compound. These were gleaned from interpretation of the shifts in binding energies and presence of multiplet splitting in the XPS of the component elements of the minerals or the intercalating compounds

Spectroscopic and Structural Studies of a Surface Active Porphyrin in Solution and in Langmuir–Blodgett Films

Controlling aggregation of the dual sensitizer–emitter (S-E) zinc tetraphenylporphyrin (ZnTPP) is an important consideration in solid state noncoherent photon upconversion (NCPU) applications. The Langmuir–Blodgett (LB) technique is a facile means of preparing ordered assemblies in thin films to study distance-dependent energy transfer processes in S-E systems and was used in this report to control the aggregation of a functionalized ZnTPP on solid substrates. This was achieved by synthetic addition of a short polar tail to one of the pendant phenyl rings in ZnTPP in order to make it surface active. The surface active ZnTPP derivative formed rigid films at the air–water interface and exhibited mean molecular areas consistent with approximately vertically oriented molecules under appropriate film compression. A red shift in the UV–vis spectra as well as unquenched fluorescence emission of the LB films indicated formation of well-ordered aggregates. However, NCPU, present in the solution phase, was not observed in the LB films, suggesting that NCPU from ZnTPP as a dual S-E required not just a controlled aggregation but a specific orientation of the molecules with respect to each other

Genomics and molecular markers for rice grain quality: a review

Rice grain quality is a benchmark of rice breeding success. Current rice breeding programs consider grain characteristics that are preferred by consumers in the rice value chain. Specific traits of quality that suit the demands of stakeholders must be targeted before, during and after breeding of new varieties. Therefore, screening tools that are environmentally independent, cheap, robust and easy to use, such as molecular markers, are needed to facilitate timely and accurate selection of traits. As a multifaceted overall phenotype and consisting of several parameters ranging from physical, textural, aroma and increasingly nutritional properties, the selection for quality has not only become about which trait(s) to focus on but is rather an issue of the combination of traits that can be incorporated into a dream variety. The more traits that are available, the more markers we need to capture these traits and feed them into the breeding and selection pipelines. This chapter reviews progress made on genomics and the molecular markers developed for quality traits of rice grains. In addition, this chapter presents the increasing need for novel phenotypes in the form of metabolites that can be traced back to the genome of rice

Congenital transmission of Trypanosoma cruzi in Argentina, Honduras, and Mexico: study protocol.

Trypanosoma cruzi has been divided into Discrete Typing Units I and non-I (II-VI). T. cruzi I is predominant in Mexico and Central America, while non-I is predominant in most of South America, including Argentina. Little is known about congenital transmission of T. cruzi I. The specific aim of this study is to determine the rate of congenital transmission of T. cruzi I compared to non-I.Journal ArticleResearch Support, N.I.H. ExtramuralSCOPUS: ar.jinfo:eu-repo/semantics/publishe