In this review the stereochemistry of palladium-catalyzed addition of nucleophiles to alkenes is discussed, and examples of these reactions in organic synthesis are given. Most of the reactions discussed involve oxygen and nitrogen nucleophiles; the Wacker oxidation of ethylene has been reviewed in detail. An anti-hydroxypalladation in the Wacker oxidation has strong support from both experimental and computational studies. From the reviewed material it is clear that anti-addition of oxygen and nitrogen nucleophiles is strongly favored in intermolecular addition to olefin-palladium complexes even if the nucleophile is coordinated to the metal. On the other hand, syn-addition is common in the case of intramolecular oxy- and amidopalladation as a result of the initial coordination of the internal nucleophile to the metal.

• Klíčová slova
• alkenes, catalysis, nucleophilic addition, palladium, stereochemistry,
• Publikační typ
• časopisecké články MeSH

Densely functionalized cyclopentane derivatives with up to four consecutive stereocenters are assembled by a tandem Michael addition/single-electron transfer oxidation/radical cyclization/oxygenation strategy mediated by ferrocenium hexafluorophosphate, a recyclable, less toxic single-electron transfer oxidant. Ester enolates were coupled with α-benzylidene and α-alkylidene β-dicarbonyl compounds with switchable diastereoselectivity. This pivotal steering element subsequently controls the diastereoselectivity of the radical cyclization step. The substitution pattern of the radical cyclization acceptor enables a switch of the cyclization mode from a 5-exo pattern for terminally substituted olefin units to a 6-endo mode for internally substituted acceptors. The oxidative anionic/radical strategy also allows efficient termination by oxygenation with the free radical 2,2,6,6-tetramethyl-1-piperidinoxyl, and two C-C bonds and one C-O bond are thus formed in the sequence. A stereochemical model is proposed that accounts for all of the experimental results and allows the prediction of the stereochemical outcome. Further transformations of the synthesized cyclopentanes are reported.

• Klíčová slova
• Michael addition, cyclization, domino reactions, electron transfer, radical reactions,
• Publikační typ
• časopisecké články MeSH

The separation of light and heavy sludge, as well as the aggregation rate of floccular sludge, are two critical aspects of the rapid granulation process in sequencing batch reactors (SBRs) in the early stages. In this study, we investigated the impact of a method to improve both sludge separation and granulation by coupling effluent sludge external conditioning with FeCl3 addition and then reintroducing it into the SBR. By supplementation with 0.1 g Fe3+ (g dried sludge (DS))-1, the concentration of extracellular polymeric substances (EPS) and sludge retention efficiency greatly increased, whereas the moisture content and specific oxygen uptake rate (SOUR) sharply decreased within 24 h external conditioning. Aggregates (1.75 ± 0.05 g·L-1) were reintroduced into the bioreactor once daily from day 13 to day 15. Afterwards, on day 17, aerobic granules with a concentration of mixed liquor suspended solids (MLSS) of 5.636 g/L, a sludge volume index (SVI30) of 45.5 mL/g and an average size of 2.5 mm in diameter were obtained. These results suggest that the external conditioning step with both air-drying and the addition of Fe3+ enhanced the production of EPS in the effluent sludge and improved rapid aggregation and high sludge retention efficiency. Consequently, the reintroduced aggregates with good traits shortened the time required to obtain mature aerobic granular sludge (AGS) and properly separate light and heavy sludge. Indeed, this method jump-started the aggregation, and rapid granulation processes were successful in this work. Additionally, while the removal efficiency of chemical oxygen demand (COD) and nitrogen from ammonium (NH4+-N) decreased when reintroducing the treated sludge into the SBR, such properties increased again as the AGS matured in the SBR, up to removal efficiencies of 96% and 95%, respectively.

• Klíčová slova
• Fe3+ addition, external conditioning, extracellular polymeric substances, rapid granulation, reintroduction,
• Publikační typ
• časopisecké články MeSH

The current study investigated the impact of two-stage water addition on the selected properties of processed cheese (PC). In particular, the above-mentioned novel approach involved adding water in two stages during the PC manufacturing process. The effects of this process on the physicochemical, viscoelastic, textural, tribological, thermal, and organoleptic properties of PC were evaluated. For all examined PC samples, the elastic modulus consistently dominated over the viscous modulus (G' > G″) across the entire frequency range. Moreover, it was observed that a smaller amount of initial water addition during the melting process resulted in a slight increase in the values of both viscoelastic moduli. The control sample exhibited the lowest lightness values, while it also showed the highest level of yellow coloring, suggesting that the two-stage addition of water affected the color of the PC samples. The results showed that the two-stage addition of water significantly influenced the physicochemical, viscoelastic, textural, tribological, thermal, and organoleptic properties of PC, leading to a modified texture, and thermal stability. Moreover, firmer PC products were obtained when a greater initial water level (first dosage; in the range of 60 to 90%) was utilized. This study could provide valuable information on the development of high-quality PC products with tailored functional properties, which can be important for the dairy industry.

• Klíčová slova
• processed cheese, textural properties, thermal properties, tribological properties, viscoelastic properties, water addition,
• Publikační typ
• časopisecké články MeSH

The treatment of pnictinidenes [2-(RNHCH2)-6-(RN=CH)C6H3]E (1As/Sb) (where E=As or Sb) with benzoyl peroxide provided compounds [2-(DippNCH2)-6-(DippN=CH)C6H3]E(O2CPh) (2As/Sb) as a result of two step procedure, i. e. oxidation of the pnictogen centre followed by the elimination of benzoic acid. The reaction between 1As and diphenyl disulfide proceeded in the same vein yielding thiophenol and [2-(DippNCH2)-6-(DippN=CH)C6H3]As(SPh) (3As). Analogous reaction of 1Sb furnished a mixture of [2-(DippNHCH2)-6-(DippN=CH)C6H3]Sb(SPh)2 (3'Sb), [2-(DippNCH2)-6-(DippN=CH)C6H3]Sb(SPh) (3Sb) and PhSH, while NMR studies proved the existence of a dynamic equilibrium between all three compounds in solution and removal of incipient PhSH was necessary for the isolation of 3Sb. Both 1As/Sb smoothly reacted with 2-nitrosotoluene leading to [2-(DippNCH2)-6-(DippN=CH)C6H3]E(O-NH-2-Me-Ph) 4As/Sb and with 4-phenyl-1,2,4-triazoline-3,5-dione giving [2-(DippNCH2)-6-(DippN=CH)C6H3]E[(N(CO)-NH(CO))N-Ph] 5As/Sb. All compounds were characterized by IR, Raman, NMR spectroscopy, and the molecular structures, except for 3As and 5Sb, were determined by single-crystal X-ray diffraction. Furthermore, we scrutinized the thermally induced reductive elimination of benzoic acid and thiophenol from 2-3As/Sb, respectively, and that of 4-phenylurazole from 5As. These eliminations involve C-H activation at the CH2N group, and the recovery of the pnictinidene center in [2,6-(RN=CH)2C6H3]E (6As/Sb). Using DFT calculations a plausible mechanism was suggested for all the investigated reactions, which are in good agreement with the experimental observations.

• Klíčová slova
• Antimony, Arsenic, Oxidative addition, Pnictinidenes, Reductive elimination,
• Publikační typ
• časopisecké články MeSH

The paper deals with the investigation of the ascorbic acid influence on the analytical results of polyphenol content in the samples of the spearmint, fennel, and thyme homogenates. The homogenates without and with addition of ascorbic acid and water were prepared and stabilized by high-pressure treatment. Their analysis was accomplished by high-performance liquid chromatography (HPLC) with DAD detection and by combination of liquid chromatography with mass spectrometry (LC-MS). Volatile terpenes were analyzed in all homogenates by combination of gas chromatography with mass spectrometry technique (GC-MS). The content of polyphenols of acidic nature, e.g., rosmarinic acid, revealed the highest difference between analytical results of the samples with and without ascorbic acid. Finally, prepared herb homogenates are suitable food supplements, which will find increasing application in various food preparations.

• Klíčová slova
• Foeniculum vulgare, Mentha spicata, Thymus vulgaris, ascorbic acid addition, herbs homogenates, phenolic compounds,
• Publikační typ
• časopisecké články MeSH

The complex (2,2'-biquinoline-κ2N,N')(carbamoylcyanonitrosomethanide-κ2N,O)chloridocopper(II) acetonitrile monosolvate, [Cu(C3H2N3O2)Cl(C18H12N2)]·CH3CN or [Cu(ccnm)Cl(biq)]·acn (acn is acetonitrile, biq is 2,2'-biquinoline and ccnm is carbamoylcyanonitrosomethanide), (I), was prepared as a result of nucleophilic addition of water to the dicyanonitrosomethanide ion in the presence of CuII and biq. IR spectroscopy confirmed the presence of ccnm, biq and acn in (I). The solid-state structure consists of the neutral complex containing ccnm and biq ligands, coordinated to the CuII atom in a bidendate chelating manner, and a chloride ligand, resulting in a distorted tetragonal pyramidal coordination of CuII. The asymmetric unit is supplemented by one molecule of solvated acn which, along with the nitrile group of ccnm, serves as an acceptor in intermolecular hydrogen bonding, creating infinite chains along the b axis. Magnetic measurements revealed a paramagnetic behaviour with a very small Weiss temperature Θ = -0.32 K and high anisotropy of the g tensor (gx = 2.036, gy = 2.120 and gz = 2.205).

• Klíčová slova
• EPR spectrum, IR spectrum, carbamoylcyanonitrosomethanide, copper(II), crystal structure, magnetic properties, nucleophilic addition,
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

A simple and elegant method for inhibition of non-templated nucleotide addition by DNA polymerases and for following DNA 3'-heterogeneity in enzymatic DNA synthesis by primer extension (PEX) is described. When template bearing ortho-twisted intercalating nucleic acid (ortho-TINA) at the 5'-end is used, non-templated nucleotide addition is reduced in both the A- and B-family DNA polymerases (KOD XL, KOD (exo-), Bst 2.0, Therminator, Deep Vent (exo-) and Taq). Formation of a single oligonucleotide product was observed with ortho-TINA modified template and KOD XL, KOD (exo-), Bst 2.0, Deep Vent (exo-) and Taq DNA polymerases. This approach can be applied to the synthesis of both unmodified and base-modified oligonucleotides.

• Klíčová slova
• DNA polymerases, Nucleotide addition, Oligonucleotides, Primer extension, Twisted intercalating nucleic acid,
• MeSH
• biotin chemie   MeSH
• DNA-dependentní DNA-polymerasy chemie   genetika   MeSH
• DNA chemie   genetika   MeSH
• Geobacillus stearothermophilus enzymologie   MeSH
• interkalátory chemie   MeSH
• pyreny chemie   MeSH
• Pyrococcus MeSH
• Thermococcus enzymologie   MeSH
• Thermus enzymologie   MeSH
• tritylové sloučeniny chemie   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• biotin MeSH
• DNA-dependentní DNA-polymerasy MeSH
• DNA MeSH
• interkalátory MeSH
• pyreny MeSH
• tritylové sloučeniny MeSH

BACKGROUND: Several raw materials and additives are used in meat production. In terms of origin, proteins which are the closest related to meat are derived from slaughtered carcasses. The aim of the work was to assess the effect of their addition on the microstructure, texture and colour of frankfurter-type meat products. RESULTS: Calleja staining, instrumental textural analysis and colour analysis were applied. The microscopic results were evaluated qualitatively. Canonical component and Tukey's HSD were used for textural and RGB evaluation. Microscopically, protein matrix formation in products containing pork haemoglobin (155_16) and pork plasma P (158_16) was found to be different from that in other samples. Texture analysis revealed differences (P < 0.05) in shear force between pork haemoglobin 155_16 and all tested samples, in the hardness between the control (154_16) and pork collagen protein (157_16) and between 157_16 and 160_16. Chewiness showed differences between control 154_16 and collagen proteins 157_16. Colour analysis showed a difference between pork haemoglobin (155_16) and other products (P < 0.05) by component analysis. CONCLUSION: All tested additives were incorporated into the protein matrix. Therefore, they may be used as additives even for unrecommended meat products. Addition of pork haemoglobin has a significant impact on the colour of the final product. © 2018 Society of Chemical Industry.

• Klíčová slova
• cooked meat product, image analysis, microstructure, protein additives, texture,
• MeSH
• barva MeSH
• chuť MeSH
• heterocyklické sloučeniny tetra- a více cyklické analýza   MeSH
• kolagen analýza   MeSH
• lidé MeSH
• manipulace s potravinami MeSH
• masné výrobky analýza   MeSH
• mechanické jevy MeSH
• potravinářské přísady analýza   MeSH
• prasata MeSH
• skot MeSH
• tvrdost MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• skot MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• haemofungin MeSH Prohlížeč
• heterocyklické sloučeniny tetra- a více cyklické MeSH
• kolagen MeSH
• potravinářské přísady MeSH

Paced Auditory Serial-Addition Task (PASAT) is a complex task commonly used to examine patients with diffuse brain damage. A visual version of the neuropsychological test (Paced Visual Serial-Addition Task, PVSAT) has also been introduced to clinical practice, and both versions were adapted to be used in neuroimaging, namely functional magnetic resonance imaging (fMRI). The aim of our work was direct comparison of auditory and visual versions of the paced serial addition test (PASAT/PVSAT) in a within-subject and within-session study and description of the commonalities and differences in both activated and deactivated brain regions. Twenty young adult right-handed healthy volunteers participated in the study and underwent whole-brain fMRI examination during PASAT and PVSAT performance. Higher-level statistical analysis was performed to generate group mean activation and deactivation maps for both tasks, their conjunctions and differences across modalities. In PASAT/PVSAT activation conjunction analysis, we confirmed the existence of a modality-independent neural network similar to working memory tasks and to previous PASAT or PVSAT studies. In PASAT/PVSAT deactivation conjunction analysis, we observed a rather symmetrical extensive pattern of deactivated regions, overlapping the default mode network. Significant differences between PASAT and PVSAT were found in the right frontal eye field (FEF) and bilaterally in the striate and extrastriate cortices. Activation in one task and deactivation in the other jointly contributed to significant differences in all occipital and occipitotemporal regions. Both tasks activated right FEF, but activation during PASAT was significantly stronger than during PVSAT. Between-modality differences should be considered when preparing and interpreting neuroimaging experiments.

• Klíčová slova
• PASAT, PVSAT, deactivation, default mode network, fMRI, verbal working memory,
• MeSH
• akustická stimulace * MeSH
• dospělí MeSH
• kognice fyziologie   MeSH
• krátkodobá paměť fyziologie   MeSH
• lidé MeSH
• magnetická rezonanční tomografie metody   MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mozek fyziologie   MeSH
• neuropsychologické testy MeSH
• plnění a analýza úkolů MeSH
• pozornost fyziologie   MeSH
• světelná stimulace * MeSH
• Check Tag
• dospělí MeSH
• lidé MeSH
• mladiství MeSH
• mladý dospělý MeSH
• mužské pohlaví MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH