Isomer-Specific Vibrational Spectroscopy of Microhydrated Lithium Dichloride Anions: Spectral Fingerprint of Solvent-Shared Ion Pairs

The vibrational spectroscopy of lithium dichloride anions microhydrated with one to three water molecules, [LiCl₂(H₂O)_1–3]⁻, is studied in the OH stretching region (3800–2800 cm⁻¹) using isomer-specific IR/IR double-resonance population labelling experiments. The spectroscopic fingerprints of individual isomers can only be unambiguously assigned after anharmonic effects are considered, but then yield molecular level insight into the onset of salt dissolution in these gas phase model systems. Based on the extent of the observed frequency shifts Δν^OH of the hydrogen-bonded OH stretching oscillators solvent-shared ion pair motifs (<3200 cm⁻¹) can be distinguished from intact-core structures (>3200 cm⁻¹). The characteristic fingerprint of a water molecule trapped directly in-between two ions of opposite charge provides an alternative route to evaluate the extent of ion pairing in aqueous electrolyte solutions.     

Gravitational stability of suspensions of attractive colloidal particles

Colloidal suspensions are susceptible to gravitationally induced phase separation. This can be mitigated by the formation of a particle network caused by depletion attraction. The effectiveness of this network in supporting the buoyant weight of the suspension can be characterized by its compressional modulus. We measure the compressional modulus for emulsion networks induced by depletion attraction and present a model that quantitatively predicts their gravitational stability. We also determine the relationship between the strength of the depletion attraction and the magnitude of the compressional modulus.     

Investigating microcrystalline cellulose crystallinity using Raman spectroscopy

Cellulose - Microcrystalline cellulose (MCC) is a semi-crystalline material with inherent variable crystallinity due to raw material source and variable manufacturing conditions. MCC crystallinity...     

Capillary Atmospheric Pressure Electron Capture Ionization (cAPECI): A Highly Efficient Ionization Method for Nitroaromatic Compounds

We report on a novel method for atmospheric pressure ionization of compounds with elevated electron affinity (e.g., nitroaromatic compounds) or gas phase acidity (e.g., phenols), respectively. The method is based on the generation of thermal electrons by the photo-electric effect, followed by electron capture of oxygen when air is the gas matrix yielding O₂ ^– or of the analyte directly with nitrogen as matrix. Charge transfer or proton abstraction by O₂ ^– leads to the ionization of the analytes. The interaction of UV-light with metals is a clean method for the generation of thermal electrons at atmospheric pressure. Furthermore, only negative ions are generated and neutral radical formation is minimized, in contrast to discharge- or dopant assisted methods. Ionization takes place inside the transfer capillary of the mass spectrometer leading to comparably short transfer times of ions to the high vacuum region of the mass spectrometer. This strongly reduces ion transformation processes, resulting in mass spectra that more closely relate to the neutral analyte distribution. cAPECI is thus a soft and selective ionization method with detection limits in the pptV range. In comparison to standard ionization methods (e.g., PTR), cAPECI is superior with respect to both selectivity and achievable detection limits. cAPECI demonstrates to be a promising ionization method for applications in relevant fields as, for example, explosives detection and atmospheric chemistry.

Various carbon dust particles

Nano-sized carbon dusts are suspected of having negative effects on human health. An exact characterization of such particles is necessary to understand possible toxic effects, i.e. in the lung. Observed by transmission electron microscopy (TEM), the carbon dusts are a composite of very small primary particles and larger agglomerates of these. A differentiation of the primary particles and agglomerates according to source is not possible by TEM, however, thermogravimetry investigations in synthetic air atmosphere are helpful. Standardized carbon black and graphite show a single-step oxidation behaviour, whereas ethene soot and diesel soot, for example, show more complex-reaction mechanisms. The results of ethene soot exemplarily demonstrate the oxidation mechanism. In addition to the oxidation reaction to carbon dioxide, a sintering process takes place. To confirm the oxidation mechanism, thermal behaviour of ethene soot has been simulated by kinetic modulation using a three-step reaction mechanism of n-th order. The reaction order indicates a complex mechanism for the first-reaction step. For the second and third-reaction step, a phase boundary mechanism could be suggested.     

Development and validation of a cost-effective,efficient, and robust liquid chromatographic method for the simultaneous determination of the acetyl and succinoyl content in hydroxypropyl methylcellulose acetate succinate polymer

A reversed-phase liquid chromatographic method was developed and validated for the determination of the content of free acetic acid, free succinic acid, acetyl substituents, and succinoyl substituents in hydroxypropyl methylcellulose acetate succinate (HPMCAS; Chemical Abstracts Service Registry No. 71138-97-1) polymer. This single new method gave accurate and precise measurement of both acetyl and succinoyl substituents, which had previously required 3 Japanese Pharmaceutical Excipients (JPE) methods to accomplish. Consequently, analysis time and turnaround time are decreased significantly. Furthermore, this method can also separate and determine the free acetic and succinic acids in HPMCAS polymer, a task that the corresponding JPE method cannot achieve. The values for accuracy (average recovery from 12 standard samples) were 99.9% for acetic acid and 99.8% for succinic acid. The values for injection precision (relative standard deviation [RSD]) were 0.11% for acetic acid and 0.28% for succinic acid. The values for intermediate precision (RSD) were 1.25% for determination of the acetyl content at the 8.78% (w/w) level and 1.33% for determination of the succinoyl content at the 10.9% (w/w) level. The values for intermediate precision (RSD) were 5.98% for determination of free acetic acid at the 0.12% (w/w) level and 5.13% for determination of free succinic acid at the 0.029% (w/w) level. The method was proven to be robust with respect to variation in the pH of the mobile phase, the concentration of potassium dihydrogen phosphate, and the flow rate. The method is well suited for quality control in today's fast-paced pharmaceutical laboratories.     

The Sasaki Hook Is Not a [Static] Implicative Connective but Induces a Backward [in Time] Dynamic One That Assigns Causes

The Sasaki adjunction, which formally encodes the logicality that different authors tried to attach to the Sasaki hook as a ‘quantum implicative connective,’ has a fundamental dynamic nature and encodes the so-called ‘causal duality’ (Coecke et al., 2001) for the particular case of a quantum measurement with a projector as corresponding self-adjoint operator. The action of the Sasaki hook ( $a\xrightarrow{S} - $ ) for fixed antecedent a assigns to some property “the weakest cause before the measurement of actuality of that property after the measurement,” i.e., ( $a\xrightarrow{S}b$ ) is the weakest property that guarantees actuality of b after performing the measurement represented by the projector that has the ‘subspace a’ as eigenstates for eigenvalue 1, say, the measurement that ‘tests’ a. The logicality attributable to quantum systems contains a fundamentally dynamic ingredient: Causal duality actually provides a new dynamic interpretation of orthomodularity. We also reconsider the status of the Sasaki hook within ‘dynamic (operational) quantum logic,’ what leads us to the claim made in the title of this paper. The Sasaki adjunction has a physical significance in terms of causal duality. The labeled dynamic hooks (forwardly and backwardly) that encode quantum measurements, act on properties as $(a_1 \xrightarrow{{\varphi _a }}a_2 ): = (a_1 \to _L (a\xrightarrow{S}a_2 ))$ and $(a_1 \xleftarrow{{\varphi _a }}a_2 ): = ((a\xrightarrow{S}a_2 ) \to _L a_1 )$ , taking values in the ‘disjunctive extension’ $DI(L)$ of the property lattice L, where $a \in L$ is the tested property and $( - \to _L - )$ is the Heyting implication that lives on DI(L). Since these hooks $( - \xrightarrow{{\varphi _a }} - )$ and $( - \xleftarrow{{\varphi _a }} - )$ extend to DI(L)×DI(L) they constitute internal operations. The transition from either classical or constructive/intuitionistic logic to quantum logic entails besides the introduction of an additional unary connective ‘operational resolution’ (Coecke, 2002a) the shift from a binary connective implication to a ternary connective where two of the arguments refer to qualities of the system and the third, the new one, to an obtained outcome (in a measurement)     

Rheological studies of concentrated guar gum

Polymers and surfactants are essential ingredients of the printing paste. Polysaccharides are used commercially to thicken, suspend or stabilise aqueous systems. Also they are used to produce gels and to act as flocculates, binders, lubricants, to serve as modifiers of film properties, and have a function as adjusters of rheological parameters. Surfactants, on the other hand, perform numerous functions acting as dispersants, wetting agents, emulsifiers and antifoaming agents. The rheological properties of polysaccharide thickeners (guar gums with different substitution levels and different producers) at different concentrations and temperatures and, second, the effects produced by the addition of nonionic surfactants (polyoxyethylene stearyl alcohols with different numbers of EO groups) have been studied under linear and nonlinear shear conditions. Experimental data have been correlated with the different models: flow curves with the Cross, Carreau and Meter-Bird model, and mechanical spectra with the generalized Maxwell model and Friedrich-Braun model. The surface tensions of aqueous systems containing polysaccharide and/or surfactants have been determined over extended concentration ranges in order to detect the CMC conditions and to provide a better understanding about the polysaccharide-surfactant interactions.