Development of a Novel Molecularly Imprinted Polyvinylimidazole/Functionalized Carbon Black Nanocomposite-based Paste Electrode for Electrochemical Sensing of Imazethapyr in Rice Samples

This paper reports the development of a simple electroanalytical method for imazethapyr (IMT) determination in rice samples based on molecularly imprinted polymer and functionalized carbon black paste electrode (MIP-fCBPE). Carbon black (CB) was functionalized by the insertion of oxygenated functional groups upon acid treatment with HNO₃ and H₂SO₄. The functionalized carbon black (fCB) presented higher performance for IMT determination than the CB without functionalization. The insertion of molecularly imprinted polyvinylimidazole (MIP-VN) in the fCBPE promoted a significant increase in the cathodic peak current even at low proportions (7.5 % w/w) due to the specific binding sites for IMT recognition. For IMT determination, DPV parameters were optimized by the Doehlert matrix applying 0.1 V for 60 s as pre-treatment in acetate buffer solution (pH 3.0) as supporting electrolyte. The proposed method showed low limit of detection (0.03 μmol L⁻¹), a wide linear range (0.10–70.00 μmol L⁻¹), and good precision in terms of repeatability of intraday measures (RSD%=3.6). The method was applied in rice samples after microwave-assisted extraction of IMT and the accuracy of the method was evaluated by addition/recovery assays (96.3–105.7 %), being statistically attested using HPLC-DAD as reference technique.     

Low field NMR for quality monitoring of 3D printed surimi from cod by-products: Effects of the pH-shift method compared with conventional washing

Implementation of three-dimensional (3D) food printing and novel analytics can reduce food waste and increase utilization of seafood by-products. Low field nuclear magnetic resonance (LF-NMR) and chemometrics were used to investigate the printability and characteristics of surimi pastes from cod by-products as affected by different processing methods (the pH-shift method vs. conventional washing), addition of salt (0, 1.5, and 3%), length of cold storage (0, 4, and 7 days) until 3D printing, and steam cooking. The analysis revealed two to three water populations in the 3D printed samples. Increasing the salt concentration induced myofibrillar swelling in the conventionally prepared surimi, whereas a more salt-induced gelling effect was observed in the pH-shift processed surimi. Cooking had a decreasing effect on the T₂₁ relaxation time and its corresponding apparent population (A₂₁), corresponding to protein denaturation and water loss during cooking. Increasing the salt concentration to 3% had a protective effect towards water exchange between the A₂₁ and A₂₃ populations in the conventionally washed samples but more subtly in the pH-shift samples. Similar trends in relaxation parameters were observed after 4 and 7 days of storage, although the intermediate population A₂₂ seemed to be most affected by the storage. Overall LF-NMR was an effective quality monitoring tool for the physicochemical changes occurring in the 3D printed surimi. The analysis showed both advantages and disadvantages of the two processing methods. However, it can clearly be concluded that increasing the salt content had a stabilizing effect on the surimi, and printing of fresh raw materials is recommended.     

Diastereoselectivity is in the Details: Minor Changes Yield Major Improvements to the Synthesis of Bedaquiline**

Bedaquiline is a crucial medicine in the global fight against tuberculosis, yet its high price places it out of reach for many patients. Herein, we describe improvements to the key industrial lithiation-addition sequence that enable a higher yielding and therefore more economical synthesis of bedaquiline. Prioritization of mechanistic understanding and multi-lab reproducibility led to optimized reaction conditions that feature an unusual base-salt pairing and afford a doubling of the yield of racemic bedaquiline. We anticipate that implementation of these improvements on manufacturing scale will be facile, thereby substantially increasing the accessibility of this essential medication.     

Heat capacity,third-law entropy,and low-temperature physical behavior of bulk hematite (α-Fe2O3)

The constant pressure heat capacity of a bulk hematite powder was measured using a Quantum Design physical properties measurement system (PPMS). The results of two series showed good precision and agreed well with measurements reported by Westrum and Grønvold. The standard molar entropy at T = 298.15 K was calculated to be (87.32 ± 2) J · mol^?1 · K^?1 for Series 1 and (87.27 ± 2) J · mol^?1 · K^?1 for Series 2, which are in good agreement with the value of (87.40 ± 0.2) J · mol^?1 · K^?1 (originally 20.889 cal · deg^?1 · mole^?1) calculated by Westrum and Grønvold. No anomaly was observed for the Morin transition, and theoretical fits below T = 15 K required a ferromagnetic T^3/2 term.     

Carbon-13 and proton NMR assignments of a new agathisflavone derivative

The (1)H and (13)C NMR spectra of 5-acetyl-7,4'-dimethoxyflavone-(6-8')-5'-acetyl-7',4'-dimethoxyflavone, a new agathisflavone derivative, were completely assigned on the basis of 1D and 2D NMR techniques.     

Polysaccharide differences between planktonic and biofilm-associated EPS from Pseudomonas fluorescens B52

The polysaccharides associated with free (planktonic) and surface-attached (biofilm) cells from cultures of Pseudomonas fluorescens strain B52 were compared. Variations in the attached matrix due to surface material (glass or stainless steel) were also analyzed. Two digestion methods were used to optimize the recoveries of sugars, uronic acids and acidic substituents. The yield of analyzable material after digestion reached 90% for the material associated to the biofilms, though only 20–30% for that bound to planktonic cells. The polysaccharide(s) in the biofilm had glucuronic and guluronic acids as main components, besides rhamnose, glucose and glucosamine. The proportion of glucuronic to guluronic acid was higher in the polysaccharide(s) found in biofilms formed on stainless steel than in those on glass.     

Abel maps for curves of compact type

Recently, the first Abel map for a stable curve of genus g≥2 has been constructed. Fix an integer d≥1 and let C be a stable curve of compact type of genus g≥2. We construct two d-th Abel maps for C, having different targets, and we compare the fibers of the two maps. As an application, we get a characterization of hyperelliptic stable curves of compact type with two components via the second Abel map.     

Decay rates for the magneto-micropolar system in $$\varvec{L^2(}\pmb {\mathbb {R}}^{\varvec{n)}}$$

In this paper, the large time decay of the magneto-micropolar fluid equations on \(\mathbb {R}^n\) (\( n=2,3\)) is studied. We show, for Leray global solutions, that \( \Vert ({\varvec{u}},{\varvec{w}},{\varvec{b}})(\cdot ,t) \Vert _{{L^2(\mathbb {R}^n)}} \rightarrow 0 \) as \(t \rightarrow \infty \) with arbitrary initial data in \( L^2(\mathbb {R}^n)\). When the vortex viscosity is present, we obtain a (faster) decay for the micro-rotational field: \( \Vert {\varvec{w}}(\cdot ,t) \Vert _{{L^2(\mathbb {R}^n)}} = o(t^{-1/2})\). Some related results are also included.