CesA protein is included in the terminal complex of <Emphasis Type="Italic">Acetobacter</Emphasis>

Cellulose is a major biopolymer on the earth that is produced by cellulose synthase in the cell membrane of living organisms. Cellulose synthase is a hetero-subunit complex composed of several different protein subunits, and is visualized as a supermolecular complex called a “terminal complex” by electron microscopy. Such supermolecular organization of an enzyme complex is believed to be important for the fiber formation or crystallization of cellulose microfibrils in cellulose biosynthesis. In the case of the cellulose-producing bacterium Acetobacter, it is hypothesized that the enzyme complex includes at least six subunits given its genetic constitution. However, to date, only three of these molecules have been experimentally confirmed as the subunits included in the terminal complex: CesB, CesD, and ccp2. In this study, we used fluorescence immuno-microscopy to show that CesA protein, the catalytic subunit, is included in the terminal complex of Acetobacter. Furthermore we discuss the obtained microscopic data for improving our understanding of the molecular organization of the bacterial cellulose synthase complex.     

Improvement in Submergence Tolerance of Cherry Through Regulation of Carbohydrate Metabolism and Plant Growth by <Emphasis Type="Italic">PsERF</Emphasis> and <Emphasis Type="Italic">PsCIPK</Emphasis>

Cherry is an important fruit tree with delicious taste and high economic value, which have been planted worldwide. However, this species cannot withstand the presence of excessive amount of water; submergence injury sometimes occurs during cultivation of cherry and results in severe economic losses. By using a submergence-tolerant germplasm Prunus serrulata “Yimeng” and a submergence-sensitive germplasm Prunus pseudocerasus “Aihua” as test materials, this study cloned PsERF and PsCIPK, which are related to submergence tolerance in cherry, and analyzed the expression of PsERF and PsCIPK in submergence-tolerant and submergence-sensitive germplasms under submergence stress; moreover, the consistency and correlation of such expression with carbohydrate metabolism and plant growth-related genes (PsPDC, PsSUS, PsRAMY, and PsEXP) were analyzed. The results showed that PsERF and PsCIPK influence the expression of PsPDC, PsSUS, PsRAMY, and PsEXP at different extents under submergence and during recovery to systematically improve the submergence resistance of P. serrulata “Yimeng”. This study lays the important theoretical and practical foundation for molecular improvement and germplasm innovation in submergence tolerance in cherry through genetic engineering.     

Enhanced bacterial cellulose production from <Emphasis Type="Italic">Gluconobacter xylinus</Emphasis> using super optimal broth

The bacterial cellulose (BC) produced by Gluconobacter xylinus due to its versatile properties, is used in healthcare and industrial applications. However, its use is restricted owing to the limited yield from the existing culture protocols. In the current study, BC production is studied in the presence of Super Optimal Broth with catabolite repression (SOC) medium which is used to revive Escherichia coli cells after electroporation or chemoporation. In SOC medium, Gluconobacter xylinus produces cellulose pellicles within 5 days of incubation with an enhanced conversion of the carbon source to cellulose compared to traditional Hestrin–Schramm (HS) medium. SOC medium also maintains the pH close to 7.0 in static cultures unlike in HS medium where the pH is acidic. The physico-chemical and morphological characteristics of the BC produced in SOC are determined using powder X-ray diffraction (pXRD), thermo gravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) and Barrett–Joyner–Halenda (BJH), and scanning electron microscopy (SEM) analyses. Our results indicate that SOC enhance the yield of bacterial cellulose and allows conversion of 50% of the carbon source to bacterial cellulose, compared to only 7% conversion in the case of traditional HS medium after 7 days of interaction. We also observe an increase in hydration capacity of BC produced using SOC as compared to HS media.     

Phase transition temperature controllable poly(acrylamide-<Emphasis Type="Italic">co</Emphasis>-acrylic acid) nanocomposite physical hydrogels with high strength

Poly(acrylamide-co-acrylic acid) nanocomposite physical (P(AAm-co-AAc)NCP) hydrogels have been prepared through the in situ free radical solution polymerization based on a “single network, dual cross-linkings” strategy. The P(AAm-co-AAc) NCP hydrogels are composed of nanobrushes of P(AAm-co-AAc) chains grafted on the surface of vinylhybrid silica nanoparticles (VSNPs). In the hydrogel system, the VSNPs act as the “analogous chemical cross-linking points” once the hydrogen bonds formed between the P(AAm-co-AAc) chains of the nanobrushes, thus leading to the fabrication of high-strength P(AAm-co-AAc) NCP hydrogels. Compared with conventional thermosensitive P(AAm-co-AAc) hydrogels, the P(AAm-co-AAc) NCP hydrogels have a broader range of phase transition temperature, which can be adjusted by altering the monomer ratio, the VSNPs concentration, the addition of urea and N,N-dimethylacrylamide (DMAAm). At the same time, the mechanical properties of the P(AAm-co-AAc) NCP hydrogels have been improved significantly by the introduction of VSNPs. Furthermore, both the phase transition and the tensile strength of the P(AAm-co-AAc) NCP hydrogels are largely influenced when Fe³⁺ ions are introduced as the ionic crosslinkers into the hydrogel networks.     

Diastereoselective synthesis of spiro derivatives of 3-substituted 2,3,4,4a,5,6-hexahydro-1<Emphasis Type="Italic">H</Emphasis>-benzo[<Emphasis Type="Italic">c</Emphasis>]quinolizines

The cyclization via the mechanism of “tert-amino effect” of 2-(4-R-piperidino)benzaldehydes with cyclic active methylene components (Meldrum’s acid, 1,3-cyclohexanedione, and N,N-disubstituted barbituric acids) proceeded stereoselectively giving spiro-joined 2,3,4,4a,5,6-hexahydro-1H-benzo[c]quinolizines with axially oriented hydrogen atoms in the positions 3 and 4a of the benzo[c]quinolizine ring.     

Compositions and structures of nanoparticles of pentagonal axial symmetry <Emphasis Type="Italic">D</Emphasis><Subscript>5<Emphasis Type="Italic">d</Emphasis></Subscript>: Nanotubes

The method of determination of the structure and the number of atoms in the shells of nanoparticles as a function of the arrangement of atoms at the symmetry elements of a symmetry group has been developed. The formulas for the calculation of the number of particles with symmetry group D _5d are reported. The number of particles in these shells is determined by three structurally invariant numbers and the “quantum number” of the group order n. The classification of all possible nanostructures with symmetry group D _5d is given: C _θ+10z , z = 0, 1, 2, …, where the basic shells are C _θ = C ₂, C ₁₀, C ₁₂. The sum rule has been obtained for the coordination numbers of shell sites located at symmetry axes. Pentagonal axial nanoparticles are shown to be the initial shells for obtaining (5,5) and (10,10) armchair nanotubes or (5,0) and (10,0) zigzag nanotubes. The general formula of these nanotubes closed with icosahedral and dodecahedral caps is N _20+10p , N _60+10p (p = 1, 2, …). The graphical constructions of all classes of nanoparticles and nanotubes of the pentagonal axial type are reported.     

Die horizontale Korrelation in π-Elektronensystemen und ihre Beschreibung durch Elektronenpaarfunktionen

Different types of pair functions (geminal products and their linear combinations) are tested with respect to their ability to describe the “horizontal correlation” of the π-electrons of butadiene. The validity of the π-electron approximation is not discussed and “full configuration interaction” within the limited LCAO basis is used as the standard to which the model calculations are referred. An APSG-function (APSG = antisymmetrized product of strongly orthogonal geminals) built up from equivalent (localized) geminals, which contains only one variational parameter is able to account for about 90% of the “horizontal correlation energy”. Both APSG and APIG functions constructed from delocalized geminals, are much less favorable. Criteria of the goodness of an approximate wave function are a) the energy b) comparison of its one- and two-particle density matrices with those obtained from “full CI”. The good results with the localized APSG function are related to the fact that electron correlation between electrons of opposite spin is (in this molecule) essential only within either of the “double bonds” of the “canonical structure”. The pertinent results are quite insensitive to different parametrization of the integrals.     

Splitting of the <Emphasis Type="Italic">d</Emphasis><Superscript><Emphasis Type="Italic">N</Emphasis></Superscript> atomic states in icosahedral 3<Emphasis Type="Italic">d</Emphasis> metal endofullerenes M@C<Subscript>60</Subscript>

Group-theoretical and quantum-chemical investigations of the spectrum of low-lying excited states have been performed by the ROHF and FCI-RAS (Full CI in Restricted Active Space) methods for 3d metal endofullerenes (MEFs) M@C₆₀ (M =Mn, Cr, and Fe) in different charged states. The major purpose of this study is quantum-chemical verification of the anomalous (“non-Bethe’s”) character of splitting of the d ^N atomic states in an electrostatic field with icosahedral symmetry, predicted previously within the theory of integral invariants theory. The interrelation between the integral invariants theory and the quantumchemical methods applied in this work is considered in detail. Our calculations suggest that the d ^N atomic states in the icosahedral field generated by fullerene C60 (I _h ) on a metal atom (ion) remain non-split for different charged states of the metal and C₆₀. Reasons for this phenomenon and other possible approaches to verification of the prediction are discussed. It is demonstrated that the d ^N states of the encapsulated metal are split in icosahedral 3d MEFs only under very strong compression of these structures.     

Characterization of neutron spectrum at Es-Salam Research Reactor using Høgdahl convention and Westcott formalism for the k<Subscript>0</Subscript>-based neutron activation analysis

For the general applicability of the k ₀-NAA method two formalisms were carried out to deal with “1/ν and non-l/ν ((n,γ)” reaction nuclides, respectively. In the Høgdahl-formalism the reactor neutron spectrum parameters, such as α and f were measured using three methods: Cd-ratio, Cdcovered and bare triple monitors. In addition, bare bi-isotopic method using Zr is also utilized for the calculation of f. According to the Westcottformalism the modified spectral index r(α)√T _n /T ₀ and g(T _n ) factor for monitoring neutron temperature T _n , were measured employing Lu as non “1/v” monitor and ¹⁹⁷Au, ⁹⁶Zr and ⁹⁴Zr as “1/v” monitors. The reduced resonance integral of lutetium s _0,Lu was also calculated. To evaluate the applicability of k ₀-NAA in our analytical system, the analysis of two kinds of SRMs was executed. The analytical results showed that the relative error of most of the elements was less than 10%.     

By-products of the cider production: an alternative source of nutrients to produce bacterial cellulose

In the present work a culture process to produce bacterial cellulose (BC) using by-products of the cider production from the Basque Country was investigated. The apple pomace was mixed with sugar cane (AR/SC medium) and the mixture was found to be a potential carbon source for Gluconacetobacter medellinensis strain ID13488 since higher cellulose production was observed with respect to the commercial Hestrin and Shramm medium (H–S). The culture media were characterized in terms of pH, oxygen and sugars consumption. The expression level of the operon bcs (genes involved in BC biosynthesis) in apple residue containing medium respect to standard H–S medium was determined. It was found that in AR/SC medium the expression levels of bcsA gene, wich is the first gene of the bcs operon, was increased in 1.5-fold respect to the H–S media which correlates with the fact that BC production in AR/SC media is higher than in H–S media. The physico-chemical and mechanical properties, microstructure, crystallinity and water holding capacity of the biosynthesized BC membranes were analyzed and it was found that, in general, the BC obtained from AR/SC medium presented superior properties than that obtained from H–S medium. In this study an economic method for BC production is proposed with suitable properties for many applications.     

Properties and <Emphasis Type="Italic">N</Emphasis>-glycosylation of recombinant endoglucanase II from <Emphasis Type="Italic">Penicillium verruculosum</Emphasis>

Cellulases are the main components of enzyme complexes used in biotransformation processes of plant raw materials into valuable commercial products. Endoglucanase II (EG II) from the Penicillium verruculosum fungus was cloned into Penicillium canescens. The homogeneous recombinant EGII form is isolated and its properties are studied in comparison with the native enzyme. The N-glycosylation sites and the structure of the N-linked glycans are been determined using mass spectrometry. The biochemical and catalytic properties, as well as the N-glycosylation type of the obtained recombinant EGII form, appear to be close to the native enzyme. At the two potential N-glycosylation sites (N42 and N194) of both forms of the enzyme, N-linked high mannose glycans (or their enzymatic “trimming” products) according to the general formula (Man)_1–9(GlcNAc)₂ are detected. No glycosylation is found at the third potential site (N19).     

Cholesteric ester of <Emphasis Type="Italic">p</Emphasis>-nitrobenzoic acid: Mesomorphic properties,crystal and molecular structures

The mesomorphic properties of cholesteric ester of p-nitrobenzoic acid С₃₄Н₄₉NO₄ were studied by differential scanning calorimetry and polarizing thermomicroscopy. Its thermal stability was determined using TGA data. The molecular and crystal structures were characterized by single-crystal X-ray diffraction. Crystals were monoclinic, а = 10.7023(4) Å, b = 10.0995(4) Å, с = 14.1563(6) Å, β = 101.499(1)°, space group Р2₁, Z = 2. An extensive molecule contained three different structural moieties: p-nitrobenzoic acid moiety, a cholesteric core consisting of four conjugated rings of different conformation, and a hydrocarbon chain of six carbon atoms. A molecule was chiral and “left” with a torsion angle of 2.6°.     

“Climate change” and the “butterfly effect” in an eighteenth century monograph

Long before the phrases “climate change” and “butterfly effect” were incorporated into the mainstream literature, these phrases appeared in an appropriate context almost verbatim in the first Chapter of a book entitled “The Emigrant” published in the mid-nineteenth century (in 1846) by Sir Francis Bond Head (1793–1875). Head was Upper Canada’s sixth Lieutenant Governor under King George IV and Queen Victoria. Head claimed that forest wildfires were “changing the climate” of North America as manifested in a warming effect “on the thermometer”. In that author’s account, these fires were provoked by First Nations to create fly-free zones meant to attract game that they could then hunt more readily. Head used language such as “swarms of little flies, strange as it may sound, are, and for many years have been, most materially altering the climate…” which is remarkably reminiscent of E. N. Lorenz’s (1917–2008) “butterfly effect” of the theory of chaotic dynamical systems. The historical context and the rationales that may have led Head to use this contemporary environmental language in a proper context are briefly discussed.     

The terms “tochnost’” and “pravil’nost’” as applied to the results of chemical analysis

In this paper, attention is given to the inadequacy of the Russian translation of the term “accuracy” as “pravil’nost’” in publications of the IUPAC recommendations for the presentation of the results of chemical analysis and vocabularies of analytical terms. The essence of the concepts tochnost’ and pravil’nost’ in Russian measurement terminology is considered in historical context, and the evolution of the concepts accuracy in the terminological standards on analytical chemistry (IUPAC Recommendations), metrology, and statistics is traced. It is demonstrated that the one-to-one correspondence between the terms “accuracy” and “tochnost’” and “trueness” and “pravil’nost’,” respectively, which occurs in the present-day standardized terminologies, should also be followed in analytical chemistry     

Structure of the stereoisomers of tetrasubstituted <Emphasis Type="Italic">p-t</Emphasis>-butylcalix[4]arene containing a morpholine fragment: Data of 1D and 2D (NOESY) NMR spectroscopy

The structure of three isomers of 5,11,17,23-tetra-t-butyl-25,26,27,28-tetrakis[(morpholidocarbonyl) methoxy]-2,8,14,20-tetrathiacalix[4]arene in conformations of partial cone, 1,3-alternant and cone was studied by the methods of 1D and 2D (NOESY) ¹H and ¹³C NMR spectroscopy in conjunction with computational modeling (semiempirical quantum-chemical PM3 calculations). Characteristic cross-peaks for each conformer in the two-dimensional NOESY spectra were established. It is found that unsymmetrical conformation of partial cone is more “flattened” as compared with highly symmetrical 1,3-alternant and cone conformations, while OCH₂C(O)NC₄H₈O substituent is located in the exo-position. Theoretical modeling is found to be more consistent with the experimental data for highly symmetrical conformations.     

Removal of aluminum by aquatic plants <Emphasis Type="Italic">Ceratophyllum demersum</Emphasis> and <Emphasis Type="Italic">Chara fragilis</Emphasis> from water of experimental ecosystems

Changes in the concentration of the aluminum ions in water of experimental systems (microcosms) have been studied. The Al ion concentration was measured by the fluorescent method. As macrophytes for microcosm incubation served hornwort Ceratophyllum demersum and stonewort Chara fragilis, with the latter hydrobiont used for the first time in similar experiments. It has been convincingly proven that, in the microcosms with the aquatic plants tested, the Al ion concentration decreased much faster than in the macrophyte-free control microcosms. The data obtained suggest that Ceratophyllum demersum and Chara fragilis are promising candidates for phytoremediation applications.     

New approaches to the calculation and interpretation of asymmetry factors of chromatographic peaks

The suitability of the determination of the asymmetry factor of chromatographic peaks by the ratio of areas of two components separated by a perpendicular dropped from the maximum of the peak to the base-line, A _s * = S _b /S _a , where symbol a corresponds to the leading edge of the peak and b is for its tailing slope, is discussed. It is demonstrated that this method enables the estimation of the asymmetry of even partially separated chromatographic signals, including those eluted “in the tail” of intense peaks of solvents. The concepts of the asymmetry index I(A _s *) and its increment ΔI(A _s *) = (A _s *)–I(A _s *) are introduced, which ensures the characterization of the asymmetry of peaks of polar analytes with respect to the asymmetry of nonpolar reference components, that is, the separation of the effects of the polarity of analytes and their quantities injected into the chromatographic column on this parameter. For the first time we revealed a correlation of the asymmetry factors of compounds of different chemical nature with such a characteristic of their polarity as the difference in chromatographic separation temperature and the normal boiling point of analytes.     

Copper(II) complex with salicylaldehyde <Emphasis Type="Italic">N</Emphasis>-(2-salicylideneiminoglutaryl)hydrazone: Synthesis and structure

A copper(II) complex with salicylaldehyde N-(2-salicylideneiminoglutaryl)hydrazone (H₄L) of the formula [Cu₂L · 2Py]₂ · 8H₂O (I) was obtained and characterized by X-ray diffraction. The crystals are monoclinic, space group P2₁, a = 13.0663 Å, b = 16.5553 Å, c = 17.7650 Å, β = 97.9420°; Z = 4. The complex is tetranuclear with a “dimer-of-dimers” structure in which the copper cations of two binuclear subunits are linked by phenoxy bridges. The EPR spectra of solutions of complex I show a superposition of two signals of four HFS lines (g ₁ = 2.111, a ₁ = 56.8 × 10^?4 cm^?1 and g ₂ = 2.183, a ₂ = 71.0 × 10^?4 cm^?1).     

Synthesis of pyranopyrazoles,benzopyrans, amino-2-chromenes and dihydropyrano[<Emphasis Type="Italic">c</Emphasis>]chromenes using ionic liquid with dual Brønsted acidic and Lewis basic sites

An efficient ionic liquid with both Brønsted acidic and Lewis basic sites, namely 1,4-dimethyl-1-(4-sulphobutyl)piperazinium hydrogen sulphate (IL1), was synthesised and characterised. IL1 is a “green”, homogeneous and reusable catalyst for: i) the synthesis of pyranopyrazoles (Va-Vj)and benzopyrans (VIa-VIj and VIIa-VIIf) at ambient temperature under solvent-free conditions and ii) the synthesis of amino-2-chromenes (VIIIa-VIIIi and IXa-IXi) and dihyropyrano[c]chromenes (Xa-Xi) at 80 °C under solvent-free conditions. The reactions were rapid with excellent product yields. In addition, the double Brønsted acid, 1,4-dimethyl-1,4-bis(4-sulphobutyl)piperazinium hydrogen sulphate (IL2), was prepared to evaluate the cooperation efficiency of their Brønsted acidic and Lewis basic sites as compared with the double Brønsted acidic sites in IL1.