How Are the Flower Structure and Nectar Composition of the Generalistic Orchid Neottia ovata Adapted to a Wide Range of Pollinators?

Plant-pollinator interactions significantly influence reproductive success (RS) and drive the evolution of pollination syndromes. In the context of RS, mainly the role of flower morphology is touched. The importance of nectar properties is less studied, despite its significance in pollination effectiveness. Therefore, the aim of this study was to test selection on flower morphology and nectar chemistry in the generalistic orchid Neottia ovata. In 2019–2020, we measured three floral displays and six flower traits, pollinaria removal (PR), female reproductive success (FRS), and determined the soil properties. The sugars and amino acids (AAs) were analyzed using the HPLC method. Data were analyzed using multiple statistical methods (boxplots, ternary plot, one-way ANOVA, Kruskal-Wallis test, and PCA). Variation of flower structure and nectar chemistry and their weak correlation with RS confirms the generalistic character of N. ovata. In particular populations, different traits were under selection. PR was high and similar in all populations in both years, while FRS was lower and varied among populations. Nectar was dominated by glucose, fructose, and included 28 AAs (Ala and Glu have the highest content). Sugars and AAs influenced mainly FRS. Among soil parameters, carbon and carbon:nitrogen ratio seems to be the most important in shaping flower structure and nectar chemistry.     

Structure-Guided Modulation of the Catalytic Properties of [2Fe−2S]-Dependent Dehydratases

The FeS cluster-dependent dihydroxyacid dehydratases (DHADs) and sugar acid-specific dehydratases (DHTs) from the ilvD/EDD superfamily are key enzymes in the bioproduction of a wide variety of chemicals. We analyzed [2Fe−2S]-dependent dehydratases in silico and in vitro, deduced functionally relevant sequence, structure, and activity relationships within the ilvD/EDD superfamily, and we propose a new classification based on their evolutionary relationships and substrate profiles. In silico simulations and analyses identified several key positions for specificity, which were experimentally investigated with site-directed and saturation mutagenesis. We thus increased the promiscuity of DHAD from Fontimonas thermophila (FtDHAD), showing >10-fold improved activity toward D-gluconate, and shifted the substrate preference of DHT from Paralcaligenes ureilyticus (PuDHT) toward shorter sugar acids (recording a six-fold improved activity toward the non-natural substrate D-glycerate). The successful elucidation of the role of important active site residues of the ilvD/EDD superfamily will further guide developments of this important biocatalyst for industrial applications.     

Evaluation of the Fractal Properties of Cluster?Cluster Aggregates

While the fractal dimension of cluster-cluster aggregates, D_f , appears to be a well-established property, the fractal prefactor, k_g (also known as structural coefficient), continues to exhibit a large range of possible values. In the present paper, an attempt is made to clarify this issue which leads to conclusive results concerning the value to adopt for the fractal prefactor of simulated aggregates. Starting from a large population of "free" numerically simulated aggregates (i.e., where no restrictions to aggregate formation were imposed) the fractal properties obtained were estimated both using morphological concepts as well as light scattering theories. Furthermore, studies for aggregates having predefined morphological k_g values (namely, k_g > 2 and ca. 1) were also performed in order to check the viability of these values. The results obtained for the three different populations of aggregates considered were used to infer, through a best-fit analysis, the fractal properties. Our best estimates are k_g      

Influence of Cesium in Pt/NaCsβ on the Physico-Chemical and Catalytic Properties of the Pt Clusters in the Aromatization ofn-Hexane

Various Pt/NaCsβ catalysts with decreasing Na/Cs ratios and a Pt/KL sample taken as a reference catalyst for aromatization ofn-hexane, have been prepared by exchange of NaCsβ and KL zeolites in a Pt tetraammine solution then calcination and reduction. The increase of the Cs content in the NaCsβ zeolitic support results in a decrease of the cyclohexane adsorption and Pt exchange capacities. The Pt/Csβ and Pt/KL samples show similar behaviors which strongly differ from those of the Na-containing Pt/NaCsβ samples in terms of (i) reducibility of the Pt ions after calcination, (ii) shape of the FTIR spectra of CO adsorbed on the Pt clusters after reduction, and (iii) catalytic activity of these clusters in the conversion ofn-hexane. In particular, the selectivity to aromatization is much higher on the Pt/Csβ and Pt/KL catalysts than on the Na-containing Pt/NaCsβ ones. The reasons for the specific behaviors of the Pt/Csβ and Pt/KL samples are discussed.     

To What Extent Is Water Responsible for the Maintenance of the Life for Warm-Blooded Organisms?

In this work, attention is mainly focused on those properties of water which are essentially changed in the physiological temperature range of warm-blooded organisms. Studying in detail the half-width of the diffusion peak in the quasi-elastic incoherent neutron scattering, the behavior of the entropy and the kinematic shear viscosity, it is shown that the character of the translational and rotational thermal motions in water radically change near T_H ~ 315 K, which can be interpreted as the temperature of the smeared dynamic phase transition. These results for bulk pure water are completed by the analysis of the isothermic compressibility and the NMR-spectra for water-glycerol solutions. It was noted that the non-monotone temperature dependence of the isothermic compressibility (β_T) takes also place for the water-glycerol solutions until the concentration of glycerol does not exceed 30 mol%. At that, the minimum of β_T shifts at left when the concentration increases. All these facts give us some reasons to assume that the properties of the intracellular and extracellular fluids are close to ones for pure water. Namely therefore, we suppose that the upper temperature limit for the life of warm-blooded organisms [T_D = (315 ± 3) K] is tightly connected with the temperature of the dynamic phase transition in water. This supposition is equivalent to the assertion that the denaturation of proteins at T ≥ T_H is mainly provoked by the rebuilding of the H-bond network in the intracellular and extracellular fluids, which takes place at T ≥ T_H. A question why the heavy water cannot be a matrix for the intracellular and extracellular fluids is considered. The lower physiological pH limit for the life of warm-blooded organisms is discussed.     

Are hormones from the neuropeptide Y family recognized by their receptors from the membrane-bound state?

Hormones and many other neurotransmitters, growth factors, odorant molecules, and light all present stimuli for a class of membrane-anchored receptors called G protein-coupled receptors (GPCRs). The GPCRs are the largest family of cell-surface receptors involved in signal transduction. About 1% of all known genes of Drosophila and more than 5% of the genes of Caenorhabditis elegans encode GPCRs. In addition, more than 50% of current therapeutic agents on the market target these receptors. When the enormous biological and pharmaceutical importance of these receptors is considered, it is surprising how little is known about the mechanism with which these receptors recognize their natural ligands. In this review we present a structural approach, utilizing techniques of high-resolution NMR spectroscopy, to address the question of whether peptides from the neuropeptide Y family of neurohormones are recognized directly from solution or from the membrane-bound state. In our studies we discovered that the structures of the membrane-bound species are better correlated to the pharmacological properties of these peptides than the solution structures are. These findings are supported by the observation that many biophysical properties of these peptides seem to be optimized for membrane binding. We finally present a scenario of possible events during receptor recognition.     

Lessons from a Minimal Genome: What Are the Essential Organizing Principles of a Cell Built from Scratch?

One of the primary challenges facing synthetic biology is reconstituting a living system from its component parts. A particularly difficult landmark is reconstituting a self-organizing system that can undergo autonomous chromosome compaction, segregation, and cell division. Here, we discuss how the syn3.0 minimal genome can inform us of the core self-organizing principles of a living cell and how these self-organizing processes can be built from the bottom up. The review underscores the importance of fundamental biology in rebuilding life from its molecular constituents.     

Are the parameters of the empirical law dependent on the dielectric properties of the ferroelectric relaxors?

The empirical law, ? = ?_m/[1 + (T − T_m)^γ/2σ²] or ? = ?_m/{1+[(T − T_m)/Δ]^ξ}, are usually used to estimate the degree of the diffused phase transition of the ferroelectric relaxors. As the values of γ or σ (ξ or Δ) are larger, the diffused phase transition is more obvious. However, values of T_m and ?_m are different upon different compositions, dopants, synthesized methods, and others. Are the values of γ and σ (ξ and Δ) affected by T_m or ?_m which represents the characteristics of the relaxors? In this paper, we utilize the experimental data of the (1 − x)Pb(Fe_2/3W_1/3)O₃–xPbTiO₃ ceramic system and the mathematical derivation to conclude that the values of γ and σ (ξ and Δ) are not affected by ?_m and T_m. Therefore, they can be used to properly describe and compare the degree of the diffused phase transition between the different samples with different compositions, dopants and synthesized methods since the noises (T_m and ?_m) are filtered in these empirical laws. Furthermore, we can clearly clarify the physical meaning of theses parameters, γ and σ (ξ and Δ), as well as their effect on the composition for the further study.     

Crystallization from the amorphous form of the nanoporous ? form of syndiotactic polystyrene

The recently discovered channel-shaped nanoporous ? crystalline form of syndiotactic polystyrene (s-PS) is generally obtained by a chloroform-induced recrystallization of samples exhibiting the helical γ crystalline form, followed by chloroform desorption in suitable conditions. This nanoporous ? crystalline form can be also obtained by crystallization of amorphous samples as induced by the same chloroform sorption-desorption procedure. This procedure, which does not affect β form samples, when applied to samples exhibiting the trans-planar α form instead leads to a recrystallization into the cavity-shaped nanoporous δ form. Both nanoporous crystalline forms (δ and ?) are obtained, by this chloroform treatment on uniaxially stretched amorphous films. In particular, polarized FTIR microscopy clearly shows that δ and ? crystalline forms prevail in central and lateral film regions, respectively. In fact, in the film central regions, higher polymer draw ratios are reached that lead to higher degrees of trans-planar crystallinity, whose chloroform-induced crystallization leads to δ form formation.     

Are the parameters of various stabilization factors estimated from mutant human lysozymes compatible with other proteins?

The various factors which contribute to protein stability havebeen extensively examined using mutant proteins, but the samekinds of substitutions have given different results dependingon the substitution sites. Recently, the contributions of somestabilization factors have been quantitatively derived as parametersby a unique equation, considering the conformational changesdue to the mutations using mutant human lysozymes [Funahashiet al. (1999) Protein Eng. 12, 841–850]. To evaluate theseparameters estimated from the mutant human lysozymes, stability–structuredatasets for the mutant T4 lysozymes were selected. The stabilitiesfor the mutant T4 lysozymes could be roughly estimated usingthese parameters. Notable differences between the estimatedand experimental stabilities were caused by the uncertaintyin part of the structures due to some Arg and Lys residues fluctuatingon the surface of the T4 lysozyme. Excluding these atoms fromthe estimation gave a good correlation between the estimatedand experimental stabilities. These results suggest that theparameters of the various stabilization factors derived fromthe mutant human lysozymes are compatible with the mutant T4lysozymes, although they should be improved with respect tosome points using more information.     

Catalytic Cracking of Gas-Oils in Electromagnetic Fields: I—Dielectric Properties of Zeolitic Catalysts

Three different zeolitic catalytic systems (13X, 5A and Ammonium Y) were tested for their dielectric properties, surface area and pore-size distribution. The 13X catalyst conductance is higher than other catalysts. The activation energies for 13X, 5A and Ammonium Y are 100, 80, and 50 kJ/mole respectively. The capacitances of 13X catalyst increase with increasing temperature causing a complex behaviour at higher temperatures and frequencies while the capacitances of 5A catalyst are usually less than 10 pF and those of Ammonium Y catalyst are erratic at low temperature. The 13X catalyst is the most suitable catalyst for its dielectric properties and proves to have a good potential to be heated by a RF dielectric reactor. The BET surface area in m²/g are 524 ± 2, 353 ± 1 and 684 ± 3 while the average pore diameters (in ) by the BET technique are 33, 22, 26 and the micropore volumes in cm³/g are 0.187, 0.125 and 0.220 for 13X, 5A and Ammonium Y respectively.     

Are all membrane reactors equal from an environmental point of view?

Membrane bioreactors are one of the most outstanding and updating technologies applied for the wastewater treatment. Different configurations and combinations of technologies are possible for this purpose. However, not only the treatment capacity has to be proved, but also the environmental performance of the different alternatives has to be evaluated under a holistic approach. Only by doing so, the selected technology will be feasible from technological and environmental perspectives.In this study, the Life Cycle Assessment was applied for the evaluation of four membrane bioreactor configurations of increasing complexity. The main contributors to the environmental impacts evaluated were identical for all the alternatives; that is, electricity use plays an important role in all the impact categories and agricultural application of sewage sludge has also a relevant contribution on toxicity-related categories and acidification potential. The comparison among the different configurations reveals an inverse relationship between the environmental costs associated to the treatment and the complexity of the treatment process.     

Does the odor from sponges of the genus Ircinia protect them from fish predators?

Caribbean sponges of the genus Ircinia contain high concentrations of linear furanosesterterpene tetronic acids (FTAs) and produce and exude low-molecular-weight volatile compounds (e.g., dimethyl sulfide, methyl isocyanide, methyl isothiocyanate) that give these sponges their characteristic unpleasant garlic odor. It has recently been suggested that FTAs are unlikely to function as antipredatory chemical defenses, and this function may instead be attributed to bioactive volatiles. We tested crude organic extracts and purified fractions isolated from Ircinia campana, I. felix, and I. strobilina at naturally occurring concentrations in laboratory and field feeding assays to determine their palatability to generalist fish predators. We also used a qualitative technique to test the crude volatile fraction from I. felix and I. strobilina and dimethylsulfide in laboratory feeding assays. Crude organic extracts of all three species deterred feeding of fishes in both aquarium and field experiments. Bioassay-directed fractionation resulted in the isolation of the FTA fraction as the sole active fraction of the nonvolatile crude extract for each species, and further assays of subfractions suggested that feeding deterrent activity is shared by the FTAs. FTAs deterred fish feeding in aquarium assays at concentrations as low as 0.5 mg/ml (fraction B, variabilin), while the natural concentrations of combined FTA fractions were >5.0 mg/ml for all three species. In contrast, natural mixtures of volatiles transferred from sponge tissue to food pellets and pure dimethylsulfide incorporated into food pellets were readily eaten by fish in aquarium assays. Although FTAs may play other ecological roles in Ircinia spp., these compounds are effective as defenses against potential predatory fishes. Volatile compounds may serve other defensive functions (e.g., antimicrobial, antifouling) but do not appear to provide a defense against fish predators.     

Effect of pH on the Catalytic Properties of Mo–V–Te–P–O Catalysts for Selective Oxidation of Isobutane

Mo–V–Te–P mixed oxide catalysts, prepared by a dry-up method at various pHs (in the range of about 1.0–9.0), have been tested in the partial oxidation of isobutane. The best catalytic performance was achieved over a catalyst prepared at a pH about 7.0. In this case, high selectivity to methacrolein (37.0%) at an isobutane conversion of 12.7% has been obtained at 380 °C. The surface V⁴⁺/V⁵⁺ ratios of the calcined samples were strongly influenced by the pH in the synthesized solution, which is one of the key factors in the catalytic performance for selective oxidation of isobutane.     

Autoignition of n-Decane Could it be a Benefit for the Selective Catalytic Reduction of NO?

The effect of void volume (apparent residence time variation) on oxidation of n-decane and on the n-decane-SCR of NO was studied on Ag/Al₂O₃ with a silver loading of 2 wt% and on Cu exchanged Y zeolite. A positive effect on the reduction of NO was observed and the better result was observed occurring with a moderate autoignition of n-decane, which corresponds to an intermediate apparent residence time.     

Hydrodechlorination of Tetrachloromethane Over Supported Platinum Catalysts. Effects of Hydrogen Partial Pressure and Catalyst’s Screening Protocol on the Catalytic Performance

Two series of silica- and alumina-supported platinum catalysts were investigated in the hydrodechlorination (HdCl) of tetrachloromethane. During an initial period of reaction carried out at a lower H₂/CCl₄ ratio the catalysts, especially those characterized by high metal dispersion, deactivated with time-on-stream. Two catalyst screening protocols were used. The first one concerned a gradually increased hydrogen partial pressure, whereas during the second one the H₂ pressure was decreased. Although, in general, the hydrogen-rich reaction conditions resulted in improved catalyst performance (higher overall activity and selectivity to CHCl₃), the second protocol led to even better results. Reasons for such a behaviour are suggested. Because of very high activity of a few tested samples, changes in CCl₄ conversion with the hydrogen partial pressure do not reflect real reaction orders in hydrogen. The same reason may lead to falsification of apparent activation energies. In certain cases the relation between conversion and hydrogen pressure showed a maximum, suggesting that HdCl undergoes via a Langmuir?CHinshelwood mechanism, when hydrogen and CCl₄ compete for metal surface sites. Both carbon- and chlorine-containing deposits were found in the post-reaction catalyst samples.     

Multiobjective Optimization of the Industrial Naphtha Catalytic Re-forming Process

1 INTRODUCTION Petroleum refining and petrochemical industries aim at maximizing one prime product while simulta-neously minimizing another accessory product to im-prove the quality of the prime product. Unfortunately, the two requirements are often conflicting or incon-sistent. It is necessary to determine the trade-off com-promises to balance the two objectives[1,2]. As the core of aromatics complex unit, catalytic reforming is a very important process for transforming naphtha into arom…