Water and oil signal assignment in low-moisture mozzarella as determined by time-domain NMR T2 relaxometry

A time-domain ¹H nuclear magnetic resonance relaxometry method was elaborated for the rapid microstructural characterization of mozzarella cheese. For this purpose, there is a strong need to know how the experimentally determined T₂ relaxation time distribution can be related to specific constituents in mozzarella. In this study, a detailed investigation is offered for fresh and aged low-moisture mozzarella cheese, often applied as a pizza cheese, by application of both a conventional Carr–Purcell–Meiboom–Gill (CPMG) sequence and a free-induction decay CPMG (FID-CPMG) sequence. The relaxation behavior was further elucidated by addition of deuterium oxide and by mild heat treatment of samples. The relaxation times of water protons in mozzarella were found to range from a few microseconds to some tens of milliseconds (in aged mozzarella) or to about hundred milliseconds (in fresh mozzarella). The upper limit of the T₂ distribution can even be extended to the seconds range upon releasing water protons from the mozzarella matrix using a mild heat treatment or upon addition of deuterated water. Both stimuli also provided evidence for the absorption of water into the cheese matrix. The potential release and uptake of water demonstrated that mozzarella acts as a very dynamic system during production and storage. The detected differences in the behavior of the water fraction between fresh and aged low-moisture mozzarella might be utilized to study the influence of either production and/or storage conditions on the cheese ripening process.     

Pre-averaged kernel estimators for the drift function of a diffusion process in the presence of microstructure noise

We consider estimation of the drift function of a stationary diffusion process when we observe high-frequency data with microstructure noise over a long time interval. We propose to estimate the drift function at a point by a Nadaraya–Watson estimator that uses observations that have been pre-averaged to reduce the noise. We give conditions under which our estimator is consistent and asympotically normal. Its rate and asymptotic bias and variance are the same as those without microstructure noise. To use our method in data analysis, we propose a data-based cross-validation method to determine the bandwidth in the Nadaraya–Watson estimator. Via simulation, we study several methods of bandwidth choices, and compare our estimator to several existing estimators. In terms of mean squared error, our new estimator outperforms existing estimators.     

Fine Tuning of β‐Peptide Foldamers: a Single Atom Replacement Holds Back the Switch from an 8‐Helix to a 12‐Helix

Cyclic homologated amino acids are important building blocks for the construction of helical foldamers. N‐aminoazetidine‐2‐carboxylic acid (AAzC), an aza analogue of trans‐2‐aminocyclobutanecarboxylic acid (tACBC), displays a strong hydrazino turn conformational feature, which is proposed to act as an 8‐helix primer. tACBC oligomers bearing a single N‐terminal AAzC residue were studied to evaluate the ability of AAzC to induce and support an 8‐helix along the oligopeptide length. While tACBC homooligomers assume a dominant 12‐helix conformation, the aza‐primed oligomers preferentially adopt a stabilized 8‐helix conformation for an oligomer length up to 6 residues. The (formal) single‐atom exchange at the N terminus of a tACBC oligomer thus contributes to the sustainability of the 8‐helix, which resists the switch to a 12‐helix. This effect illustrates atomic‐level programmable design for fine tuning of peptide foldamer architectures.     

Gravity-driven azimuthal flow of a layer of thixotropic fluid on the inner surface of a horizontal tube

The gravity-driven azimuthal flow of a layer of thixotropic paint on the inner surface of a horizontal tube is studied, considering surface tension effects. Using the lubrication theory, it was shown that a non-linear, fourth-order partial differential equation governs the time evolution of the paint layer thickness distribution along the azimuthal coordinate. Three parameters arise in the analysis, namely, the Bond number and two rheology-related parameters. The governing equation is integrated via a second-order accurate finite-difference scheme. The results showed that, in situations where the capillary force dominates (Bo < 1), displacement of the paint after application is very slow. For situations where the gravity force dominates (Bo > 1), an undulation on the interface arises near the tube bottom at sufficiently large times.     

Fluctuation theorems and 1/f noise from a simple matrix

Here we present a model for a small system combined with an explicit entropy bath that iscomparably small. The dynamics of the model is defined by a simple matrix, M. Each row ofM corresponds to a macrostate of the system, e.g. net alignment, while the elements in therow represent microstates. The constant number of elements in each row ensures constantentropy, which allows reversible fluctuations, similar to information theory where aconstant number of bits allows reversible computations. Many elements in M come from themicrostates of the system, but many others come from the bath. Bypassing the bath statesyields fluctuations that exhibit standard white noise; whereas with bath states the powerspectral density varies as S(f) ∝ 1 /f overa wide range of frequencies, f. Thus, the explicit entropy bath is the mechanismof 1/f noisein this model. Both forms of the model match Crooks’ fluctuation theorem exactly,indicating that the theorem applies not only to infinite reservoirs, but also tofinite-sized baths. The model is used to analyze measurements of 1/f-like noise from asub-micron tunnel junction.     

Influence of Catalyses on the Preparation of YVO<Subscript>4</Subscript>:Eu<Superscript>3+</Superscript> Phosphors by the Sol–gel Methodology

YVO(4):Eu(3+) phosphors have been prepared by the hydrolytic sol-gel methodology, with and without alkaline catalyst. The solid powder was obtained by reaction between yttrium III chloride and vanadium alkoxides; the europium III chloride was used as structural probe. The powder was treated at 100, 400, 600, or 800 °C for 4 h. The samples were characterized by X-ray diffraction, thermal analysis, and photoluminescence. The XRD patterns revealed YVO(4) crystalline phase formation for the sample prepared without the catalyst and heat-treated at 600 °C and for the sample prepared in the presence of ammonium as catalyst and heat-treated at 100 °C. The average nanosized crystallites were estimated by the Scherrer equation. The sample which was produced via alkaline catalysis underwent weight loss in two stages, at 100 and 400 °C, whereas the sample obtained without catalyst presented four stages of weight loss, at 150, 250, 400, and 650 °C. The excitation spectra of the samples treated at different temperatures displayed the charge transfer band (CTB) at 320 nm. PL data of all the samples revealed the characteristic transition bands arising from the (5)D(0) → (5)F(J) (J = 0, 1, 2, 3, and 4) manifolds under maximum excitation at 320, 394, and 466 nm in all cases. The (5)D(0) → (7)F(2) transition often dominates the emission spectra, indicating that the Eu(3+) ion occupies a site without inversion center. The long lifetime suggests that the matrix can be applied as phosphors. In conclusion, the sol-gel methodology is a very efficient approach for the production of phosphors at low temperature.     

Synthesis of 2-aminocyclopropyl pyrrolidines from glycoaminonitriles

We have developed an expedient method for the synthesis of 2-aminocyclopropyl pyrrolidines from carbohydrate-derived α-aminonitriles involving up to five or six steps, the key step being the titanium-mediated aminocyclopropanation on the aminonitrile moiety, followed by cleavage of the protecting groups.