The Effect of α-, β- and γ-Cyclodextrin on Wheat Dough and Bread Properties

Cyclodextrins (CDs) are cyclic oligosaccharides that have found widespread application in numerous fields. CDs have revealed a number of various health benefits, making them potentially useful food supplements and nutraceuticals. In this study, the impact of α-, β-, and γ-CD at different concentrations (up to 8% of the flour weight) on the wheat dough and bread properties were investigated. The impact on dough properties was assessed by alveograph analysis, and it was found that especially β-CD affected the viscoelastic properties. This behavior correlates well with a direct interaction of the CDs with the proteins of the gluten network. The impact on bread volume and bread staling was also assessed. The bread volume was in general not significantly affected by the addition of up to 4% CD, except for 4% α-CD, which slightly increased the bread volume. Larger concentrations of CDs lead to decreasing bread volumes. Bread staling was investigated by texture analysis and low field nuclear magnetic resonance spectroscopy (LF-NMR) measurements, and no effect of the addition of CDs on the staling was observed. Up to 4% CD can, therefore, be added to wheat bread with only minor effects on the dough and bread properties.     

Nondislocation origin of GaAs nanoindentation pop-in event

The present Letter demonstrates a pop-in event that is caused by a nanoindentation-induced phase transformation in GaAs, and not accompanied by any dislocation nucleation. Our computer simulations reveal the appearance of the new phase, documented by the structural correlation functions and visualization of the atomic positions. This challenges the orthodox view that the initial pop-in event reflects nucleation of dislocations or their movement, and has a bearing on materials where dislocation activity is not present.     

Chemical Probing of the Human Sirtuin 5 Active Site Reveals Its Substrate Acyl Specificity and Peptide‐Based Inhibitors

Sirtuins are NAD⁺‐dependent deacetylases acting as sensors in metabolic pathways and stress response. In mammals there are seven isoforms. The mitochondrial sirtuin 5 is a weak deacetylase but a very efficient demalonylase and desuccinylase; however, its substrate acyl specificity has not been systematically analyzed. Herein, we investigated a carbamoyl phosphate synthetase 1 derived peptide substrate and modified the lysine side chain systematically to determine the acyl specificity of Sirt5. From that point we designed six potent peptide‐based inhibitors that interact with the NAD⁺ binding pocket. To characterize the interaction details causing the different substrate and inhibition properties we report several X‐ray crystal structures of Sirt5 complexed with these peptides. Our results reveal the Sirt5 acyl selectivity and its molecular basis and enable the design of inhibitors for Sirt5.     

Back cover: Mn2+ or Mn3+? Investigating transition metal dissolution of manganese species in lithium ion battery electrolytes by capillary electrophoresis

A new CE method with ultraviolet–visible detection was developed in this study to investigate manganese dissolution in lithium ion battery electrolytes. The aqueous running buffer based on diphosphate showed excellent stabilization of labile Mn³⁺, even under electrophoretic conditions. The method was optimized regarding the concentration of diphosphate and modifier to obtain suitable signals for quantification. Additionally, the finally obtained method was applied on carbonate-based electrolytes samples. Dissolution experiments of the cathode material LiNi_0.5Mn_1.5O₄ (lithium nickel manganese oxide [LNMO]) in aqueous diphosphate buffer at defined pH were performed to investigate the effect of a transition metal-ion-scavenger on the oxidation state of dissolved manganese. Quantification of both Mn species revealed the formation of mainly Mn³⁺, which can be attributed to a comproportionation reaction of dissolved and complexed Mn²⁺ with Mn⁴⁺ at the surface of the LNMO structure. It was also shown that the formation of Mn³⁺ increased with lower pH. In contrast, dissolution experiments of LNMO in carbonate-based electrolytes containing LIPF₆ showed only dissolution of Mn²⁺.     

Effective Control of the Electron-donating Ability of Phosphines by using Phosphazenyl and Phosphoniumylidyl Substituents

Phosphoniumylidyl and phosphazenyl groups are effective substituents to increase the electron-donating ability of tertiary phosphines. However, the influence of structural variations among those substituents on the electronic properties of the phosphines is little explored. Herein, we show that protonation of the ylidic carbon atom of phosphoniumylidyl phosphines increases the Tolman electronic parameter (TEP) by ΔTEP = 16.0–18.8 cm^–1. Furthermore, phosphazenyl phosphines were synthesized with isopropyl groups (NP{iPr}₃) and tetramethylguanidino groups (NP{tmg}₃) at the phosphonium center. Determination of their TEP values reveals a remarkable low substituent parameter of χ = –18.5 cm^–1 for the NP(tmg)₃ group. In addition, we prepared the corresponding gold(I) complexes and determined their solid-state structures using single-crystal X-ray diffraction studies to analyze the steric profile of the new phosphine ligands.     

Polymerization of phosphorus containing cyclic monomers: Synthesis of polymers related to biopolymers

The mechanism of polymerization is discussed, in which cyclic esters of phosphoric acid, and related compounds are converted into linear macromolecules, modelling nucleic and teichoic acid backbones. Structures like deoxyribose polyphosphate and glycerol polyphosphate were prepared from the corresponding cyclic compounds. These polymerizations involve heterolytic breaking of the P-O bond in the cyclic monomer and proceed by ionic mechanism. Both 5- and 6-membered monomers have been polymerized. The thermodynamic parameters of the ring-chain interconversion were determined; the 5-membered rings polymerization is driven by the exothermicity of the ring-opening, whereas polymerization of several 6-membered rings is endothermic and allowed because of the positive change of entropy. Anionic polymerization, and particularly the pseudo(coordinate)anionic polymerization provides, in contrast to the cationic process, high-molecular-weight polymers with more uniform structure. Anionic polymerization proceeds mostly (at the applied conditions) on the macroion – -pairs. The elementary reactions consist of the nucleophilic attack of the paired macroanions on the phosphorus atom in the cyclic monomer molecule. Rate constants of the elementary reactions for the model monomers will be presented. Stereochemistry of the propagation steps is shown to be governed by the statistical ring-opening, leading to the three kinds of polymer units (head-to-tail and two symmetrical units). Apart from the ring-opening, the polyaddition of diepoxides to phosphorous and phosphoric acids is described. Finally, a few examples of preparation of models of biopolymers are given, namely poly(deoxyribose phosphate) and poly(glycerol phosphate).     

High-temperature heat capacity,thermodynamic properties and debye temperature of CuGe2P3

The heat capacity at constant pressure of CuGe₂P₃ is measured in the temperature range from 180 to 550 K. Standard enthalpies and entropies relative to 298.15 K are calculated from the heat capacity data. The Debye temperature in the high-temperature limit is estimated to be about 710 K.     

Electrical properties of AgGaSe2 epitaxial layers

Epitaxial layers of AgGaSe₂ with thicknesses in the range from 50 to 70 nm were deposited onto (111)A-oriented semi-insulating GaAs substrates by flash-evaporation in the substrate temperature range T_S = 825 … 900 K. Films grown at T_S ≦ 850 K are n-type conducting whereas p-type conductivity was observed at T_S ≧ 875 K. In the p-type samples two acceptor states with ionization energies of 60 and 410 meV were found from an analysis of the electrical measurements.     

Deposition of InP on GaAs Substrates in the InP/PCl3/H2 System

Vapour phase epitaxial layers of InP were deposited onto (111)A-, (111)B-, (001)-, and (110)-oriented GaAs substrates in the InP/PCl₃/H₂ system using a close-space technique. It is shown that the dependence of the layer quality on the substrate orientation is due to differences in the initial growth stages. Results on the growth rates and the electrical properties of the layers are reported.     

Antidepressant-like Effects of Combined Fluoxetine and Zinc Treatment in Mice Exposed to Chronic Restraint Stress Are Related to Modulation of Histone Deacetylase

Chronic stress is the key factor contributing to the development of depressive symptoms. Chronic restraint stress (CRS) is well validated and is one of the most commonly used models to induce depressive-like behavior in rodents. The present study aimed to evaluate whether fluoxetine (FLU 5 mg/kg) and zinc (Zn 10mg/kg) given simultaneously induce a more pronounced antidepressant-like effect in the CRS model than both those compounds given alone. Behavioral assessment was performed using the tail suspension and splash tests (TST and ST, respectively). Furthermore, the effects of CRS, FLU and Zn given alone and combined treatment with FLU + Zn on the expression of proteins involved in the apoptotic, inflammatory, and epigenetic processes were evaluated in selected brain structures (prefrontal cortex, PFC; and hippocampus, Hp) using Western blot analysis or enzyme-linked immunosorbent assays (ELISA). The results obtained indicated that three hours (per day) of immobilization for 4 weeks induced prominent depressive symptoms that manifested as increased immobility time in the TST, as well as decreased number and grooming time in the ST. Behavioral changes induced by CRS were reversed by both FLU (5 and 10 mg/kg) or Zn (10 mg/kg). Zinc supplementation (10 mg/kg) slightly increases the effectiveness of FLU (5 mg/kg) in the TST. However, it significantly increased the activity of FLU in the ST compared to the effect induced by FLU and Zn alone. Biochemical studies revealed that neither CRS nor FLU and Zn given alone or in combined treatment alter the expression of proteins involved in apoptotic or inflammatory processes. CRS induced major alterations in histone deacetylase (HDAC) levels by increasing the level of HADC1 and decreasing the level of HADC4 in the PFC and Hp, decreasing the level of HADC6 in the PFC but increasing it in Hp. Interestingly, FLU + Zn treatment reversed CRS-induced changes in HDAC levels in the Hp, indicating that HDAC modulation is linked to FLU + Zn treatment and this effect is structure-specific.