Effect Of Structural Features Research Articles

Sugar-Based Surfactants: Effects of Structural Features on the Physicochemical Properties of Sugar Esters and Their Comparison to Commercial Octyl Glycosides.

Two series of sugar esters with alkyl chain lengths varying from 5 to 12 carbon atoms, and with a head group consisting of glucose or galactose moieties, were synthesized. Equilibrium surface tension isotherms were measured, yielding critical micellar concentration (CMC) surface tensions at CMC (γcmc) and minimum areas at the air-water interface (Amin). In addition, Krafft temperatures (Tks) were measured to characterize the ability of molecules to dissolve in water, which is essential in numerous applications. As a comparison to widely used commercial sugar-based surfactants, those measurements were also carried out for four octyl d-glycosides. Impacts of the linkages between polar and lipophilic moieties, alkyl chain lengths, and the nature of the sugar head group on the measured properties were highlighted. Higher Tk and, thus, lower dissolution ability, were found for methyl 6-O-acyl-d-glucopyranosides. CMC and γcmc decreased with the alkyl chain lengths in both cases, but Amin did not appear to be influenced. Both γcmc and Amin appeared independent of the ester group orientation. Notably, alkyl (methyl α-d-glucopyranosid)uronates were found to result in noticeably lower CMC, possibly due to a closer distance between the carbonyl function and the head group.

EFFECT OF MICROSTRUCTURES ON MASS TRANSFER INSIDE A HIERARCHICALLY STRUCTURED POROUS CATALYST

In this paper, the pore network model to investigate the reaction-diffusion process in the hierarchically structured porous catalyst particle is extended to consider the phenomenon of deactivation by coking. In this framework, the interaction of internal particle pore structure and mass transfer under the condition of coke deposition is examined. Then, the effect of structural features, namely macroporosity and pore size ratio, the deactivation properties, the maximum loading of coke, as well as the transport properties, the pore Damköhler number on the net reaction rate, and deactivation of the particle have been investigated. Three deactivation mechanisms are accounted for, namely, the site coverage, the pore narrowing, and the pore blockage. It is found that the deactivation of the catalyst particle can be divided into two conditions: the kinetic deactivation and the structural deactivation. It is shown that depending on the Damköhler number, increasing the macroporosity does not necessarily improve the reactivity and deactivation resistance of the catalyst. The key finding of this work is to demonstrate and quantify how changing the typical fresh catalyst microstructure into a hierarchical one influences the reactivity and deactivation.

Effect of Structural Features on Microstructure and Properties Homogeneity Based on Quantification and Statistical Analysis for Large-Scaled Complex Titanium Alloy Castings

Effect of Structural Features on Microstructure and Properties Homogeneity Based on Quantification and Statistical Analysis for Large-Scaled Complex Titanium Alloy Castings

Stereospecific Self-Assembly Processes of Porphyrin-Proline Conjugates: From the Effect of Structural Features and Bulk Solvent Properties to the Application in Stereoselective Sensor Systems.

Conjugating the porphyrin ring with an amino acid via amide linkage represents a straightforward way for conferring both amphiphilicity and chirality to the macrocycle. Proline residue is a good choice in this context since its conformational rigidity allows for porphyrin assembling where molecular chirality is efficiently transferred and amplified using properly honed aqueous environments. Herein, we describe the evolution of the studies carried out by our group to achieve chiral systems from some porphyrin-proline derivatives, both in solution and in the solid state. The discussion focuses on some fundamental aspects reflecting on the final molecular architectures obtained, which are related to the nature of the appended group (stereochemistry and charge), the presence of a metal ion coordinated to the porphyrin core and the bulk solvent properties. Indeed, fine-tuning the mentioned parameters enables the achievement of stereospecific structures with distinctive chiroptical and morphological features. Solid films based on these chiral systems were also obtained and their recognition abilities in gaseous and liquid phase are here described.

Extracting information from X-ray diffraction patterns containing Laue oscillations

Abstract The presence of Laue oscillations in a film grown on a solid surface is broadly taken as indicating a high quality, crystallographically aligned film of the targeted compound. In this paper we briefly review the origins of both Laue oscillations and Kiessig fringes and show how they can be used together to determine if extra thickness exists above or below the coherently diffracting domains. The differences between experimental and “ideal” films are discussed and the effect of structural features (roughness, different thickness coherently diffracting domains and thickness in addition to the coherently diffracting domains) are illustrated with experimental and simulated data for metal and mixed-metal chalcogenide films of titanium, bismuth, vanadium/iron, and bismuth/molybdenum. Examples are given showing how quantitative information can be extracted from experimental diffraction patterns.

Abraham model solute descriptors: effect of structural features on the calculated numerical descriptor values for vanillin and select derivatives

ABSTRACT Abraham model solute descriptors are determined for vanillin and five select derivatives (o-vanillin, isovanillin, vanillic acid, vanillyl alcohol and ethylvanillin) based on experimental solubility and partition coefficient data that we were able to find in the published literature. The solute descriptor values reported in the current communication back-calculate the observed experimental data to within standard errors of 0.12 log units (or less). The calculated solute descriptors can be used to predict the solubility of the vanillin and the five select derivatives in additional organic mono-solvents and binary aqueous-ethanol solvent mixtures using published Abraham model correlations.

Effect of structural features on the stability and bactericidal potential of two cadmium coordination polymers

Two mixed ligand Cd(ii) coordination polymers have been synthesized using three methods byin situdecarboxylation of phenylmalonic acid. CPs were screened for their antibacterial activities and the influence of structural properties was studied.

Effect of Structural Features of Pectin on Its Complexation with Lysozyme

The interaction between lysozyme (Lys) and pectins with different net and local charges and with block (BD) and random (RD) distributions of methoxyl groups is studied via dynamic light scattering, turbidimetry, high-resolution optical microscopy, and electrophoretic mobility measurements. RD 16.2, RD 38.2, BD 16.9, and BD 33.1 form water-soluble complexes at pH 5.1, ionic strength I = 0.01, and q 3 × 10–3. The corresponding parameters for RD 66.5 and BD 68.2 are higher: q ≅ 3 × 10–3 up to q ≅ 0.01, and q higher than 0.01. Optical microscopy shows that the complexes between Lys and BDs are large (15–20 μm) for all studied values of the degree of methoxylation (DM), while the average size of RD-based complexes is substantially lower (from 0.6 to 3 μm) and depends on the DM. The BD-based complexes have a gel-like morphology irrespective of the DM, whereas particles of RD-based complex have the form of both coacervate drops and gel-like particles, depending on the DM. The threshold value for ionic strength Iset above which Lys does not form complexes with RD and BD is found to be 0.11. That being so, the values for Iset and pHset for the BD/Lys systems are independent of the pectin DM, while for the RD/Lys systems these parameters diminish considerably with an increase in the DM. The dependence of complexation of Lys and pectin on I has a non-monotonic character with a maximum at I = 0.03 and 0.06 for RD and BD, respectively. Our understanding of the effect that the total charge of a pectin molecule and its distribution along the chain has on the complexation of pectin and a protein is important for our ability to predict the stability of the food product structure.

Effect of Structural Features on the Superhydrophobicity of SiO2-Based Coatings.

A detailed correlation between topographical features and wettability of chemically modified coatings based on silica nanoparticles (SiO2) was performed. In this study, hierarchical structures were prepared by the layer-by-layer (LbL) technique using two different approaches: random roughened surfaces were obtained by exploring stacking defects spontaneously arisen after 15, 30, and 45 assembly cycles of 22 nm SiO2, and a particular structure, commonly known as raspberry-like, was obtained by depositing 22 nm SiO2 over the first deposited 400 nm SiO2. As an intrinsic attribute of the assembly process, the average slope of random roughened surfaces seems to be constant and virtually independent of the number of deposited layers. Additionally, the local slopes are always lower than a critical value (Φcrit) required to stabilize the solid-liquid-air interface; thus, a fully wetted Wenzel state is invariably observed with water contact angles (WCAs) ∼130°. On the other hand, since the local slopes of the raspberry-like structure follow a nearly spherical curvature, small SiO2 can stabilize the solid-liquid-air interface by increasing the local contact angle and avoid the deep penetration of water into the surface asperities, resulting in a WCA ∼167°. The results also suggest that nanoroughness might also play an important role in the pinning effect of the solid-liquid-air contact line, favoring the maintenance of superhydrophobicity of raspberry-like surfaces.

Effect of Structural Features on Ionic Conductivity and Dielectric Response of PVA Proton Conductor-Based Solid Polymer Electrolytes

In this study, the effect of structure on the ionic conductivity and dielectric response of polyvinyl alcohol solid polymer electrolyte films doped with ammonium nitrate (NH4NO3) was investigated. Structural studies show that the solid polymer electrolytes in a suitable salt ratio enhance the amorphous fraction of the host matrix and facilitate the fast movement of H-ions, resulting in the enhancement of electrical conductivity. The highest ionic conductivity at room temperature (5.17 × 10−5 S/cm) was achieved by incorporating 30 wt.% of NH4NO3, which shows the maximum ion dissociation in the host matrix due to ion–polymer interaction. The reduction in the ionic conductivity at higher salt concentrations (above 30 wt.%) is the consequence of a decrease in the carrier concentration and its movement, respectively, due to the formation of ion pairs and a reduction in the amorphous fraction of the system. A broad asymmetric peak of the imaginary part of the electrical modulus suggests a temperature-dependent non-Debye relaxation process for the present system.

Steviol glycosides, an edible sweet surfactant that can modulate the interfacial and emulsifying properties of soy protein isolate solution

Abstract Steviol glycosides have been widely used in liquid food as sweeter and flavor enhancer, but their interfacial physicochemical properties in oil/water system lack of study, especially the effect of structural features on their interfacial activities. The present study investigated the influence of steviol glycosides structure on their surface activities and the synergistic effect with soy protein isolate on the solution interfacial activities. The surface activities of the steviol glycosides followed the reverse sequence as their glucosyl groups numbers: monoglucosyl rebaudioside A

Sustainable Political Social Media Marketing: Effects of Structural Features in Plain Text Messages

The success of Barack Obama’s 2008 U.S. presidential campaign led politicians and voters all over the world to pay attention to social media. Including Donald Trump for his upcoming 2020 re-election, many politicians around the world have used social media for their political campaigns. While some social media can deliver information in various forms (i.e., video, audio, and interactive content), some popular ones, such as Twitter, are still focused mostly on plain text messaging. With political marketing using simple text messages via social media, there is a need to examine ways of creating messages that ultimately help shape voters’ perception of politicians and eventually win the election. Based on communication science, this study attempts to test the limited capacity model of motivated mediated message processing by examining whether this model can be applied to the simplest form of mediated message, which is plain text. In order to do so, structural features of text messages exchanged on social media engaged in political campaigns, namely linguistic formality and network-mediated human interactivity, are manipulated in an experiment. Findings suggest that linguistic formality and human interaction in plain text messages influence perceived friendliness, truthfulness, and dependability of the message source (politicians), as well as the receivers’ (constituents’) behavioral intent to vote for the message source in an upcoming election. This implies that politicians should pay more attention on sustainable political marketing through appropriate manipulation of structural features in social media messages.

The effect of structural features of heat stabilizers during the cooling time of oil in a stopped oil pipeline

According to the annual reports of oil companies, there is an increase in the production of high-viscosity and ultra-high-viscosity oil. At the same time, responsibility for the transportation of the product, which can occur under unsteady conditions and lead to emergency situations, is intensified. Thus, a forced shutdown of an oil pipeline during transportation of high-viscosity oil can cause the product to cool below critical temperatures, and further launch of the oil pipeline will be impossible. In this regard, the task of calculating the safe shutdown time of the oil pipeline has particular relevance. We have carried out a numerical study to determine the effect of the structural features of the heat stabilizer during the cooling time of oil in a stopped oil pipeline. The values of the cooling time of oil from the action of heat stabilizers, made by various manufacturers, were established. In addition, the effect of the length of the evaporation part and the installation distance of the heat stabilizer from the oil pipeline during the cooling time was studied.

Visualizing cellulase adsorption and quantitatively determining cellulose accessibility with an updated fungal cellulose-binding module-based fluorescent probe protein

BackgroundCellulose accessibility to cellulases (CAC) is a direct factor determining the enzymatic digestibility of lignocellulosic cellulose. Improving CAC by pretreatment is a prerequisite step for the efficient release of fermentable sugars from biomass cell wall. However, conventional methods to study the porosimetry of solid materials showed some limitations to be used for investigating CAC. In this work, an updated novel fusion protein comprising a fungal cellulose-binding module (CBM) from Cel7A cellobiohydrolase I (CBH I) of Trichoderma reesei QM6 and a di-green fluorescent protein (GFP2) was constructed for quantitative determination of CAC.ResultsThe obtained probe protein had similar molecular size (e.g., weight) with that of Cel7A and could give detectable signal for quantitative analysis. Several construction strategies were compared with regard to the site of His-tag and order of CBM and GFP2 modules in the protein sequence, in order to achieve good expression quantity and usability of the probe protein. His6–CBM–GFP2 has been identified as the best probe protein for investigating the effects of structural features of cellulosic substrates on cellulose accessibility. Substrate samples with different contents of xylan, lignin, and degree of substitution of cellulose –OH by formyl group were obtained, respectively, by mild H2SO4 pre-hydrolysis, NaClO2 selective delignification, and treatment of filter paper cellulose with concentrated formic acid. The determined CAC was in a wide range of 0.6–20.4 m2/g depending on the contents of hemicelluloses, lignin, and formyl group as well as cellulose degree of crystallization.ConclusionsThe obtained fusion probe protein could be used as a versatile tool to quantitatively investigate the impacts of biomass structural features on CAC and hydrolyzability of cellulose substrates, as well as nonproductive adsorption of cellulase enzymes on lignin.

Amino acid conjugated antimicrobial drugs: Synthesis, lipophilicity- activity relationship, antibacterial and urease inhibition activity

Present work describes the in vitro antibacterial evaluation of some new amino acid conjugated antimicrobial drugs. Structural modification was attempted on the three existing antimicrobial pharmaceuticals namely trimethoprim, metronidazole, isoniazid. Twenty one compounds from seven series of conjugates of these drugs were synthesized by coupling with some selected Boc-protected amino acids. The effect of structural features and lipophilicity on the antibacterial activity was investigated. The synthesized compounds were evaluated against five standard American type culture collection (ATCC) i.e. Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa and Salmonella typhi strains of bacteria. Our results identified a close relationship between the lipophilicity and the activity. Triazine skeleton proved beneficial for the increase in hydrophobicity and potency. Compounds with greater hydrophobicity have shown excellent activities against Gram-negative strains of bacteria than Gram-positive. 4-amino unsubstituted trimethoprim-triazine derivative 7b have shown superior activity with MIC = 3.4 μM (2 μg/mL) for S. aureus and 1.1 μM (0.66 μg/mL) for E. coli. The synthesized compounds were also evaluated for their urease inhibition study. Microbial urease from Bacillus pasteurii was chosen for this study. Triazine derivative 7a showed excellent inhibition with IC50 = 6.23 ± 0.09 μM. Docking studies on the crystal structure of B. pasteurii urease (PDB ID 4UBP) were carried out.

Comparative evaluation of Populus variants total sugar release and structural features following pretreatment and digestion by two distinct biological systems

BackgroundPopulus natural variants have been shown to realize a broad range of sugar yields during saccharification, however, the structural features responsible for higher sugar release from natural variants are not clear. In addition, the sugar release patterns resulting from digestion with two distinct biological systems, fungal enzymes and Clostridium thermocellum, have yet to be evaluated and compared. This study evaluates the effect of structural features of three natural variant Populus lines, which includes the line BESC standard, with respect to the overall process of sugar release for two different biological systems.ResultsPopulus natural variants, SKWE 24-2 and BESC 876, showed higher sugar release from hydrothermal pretreatment combined with either enzymatic hydrolysis or Clostridium thermocellum fermentation compared to the Populus natural variant, BESC standard. However, C. thermocellum outperformed the fungal cellulases yielding 96.0, 95.5, and 85.9% glucan plus xylan release from SKWE 24-2, BESC 876, and BESC standard, respectively. Among the feedstock properties evaluated, cellulose accessibility and glycome profiling provided insights into factors that govern differences in sugar release between the low recalcitrant lines and the BESC standard line. However, because this distinction was more apparent in the solids after pretreatment than in the untreated biomass, pretreatment was necessary to differentiate recalcitrance among Populus lines. Glycome profiling analysis showed that SKWE 24-2 contained the most loosely bound cell wall glycans, followed by BESC 876, and BESC standard. Additionally, lower molecular weight lignin may be favorable for effective hydrolysis, since C. thermocellum reduced lignin molecular weight more than fungal enzymes across all Populus lines.ConclusionsLow recalcitrant Populus natural variants, SKWE 24-2 and BESC 876, showed higher sugar yields than BESC standard when hydrothermal pretreatment was combined with biological digestion. However, C. thermocellum was determined to be a more robust and effective biological catalyst than a commercial fungal cellulase cocktail. As anticipated, recalcitrance was not readily predicted through analytical methods that determined structural properties alone. However, combining structural analysis with pretreatment enabled the identification of attributes that govern recalcitrance, namely cellulose accessibility, xylan content in the pretreated solids, and non-cellulosic glycan extractability.

Effect of structural features and loading parameters on bond in reinforced concrete under repeated load

Some reinforced concrete structures are subjected to repeated loads during their service lives, and the effect of repeated loads is stronger and more complex than static loads. This paper reports the results of the tests performed on cylindrical reinforced concrete specimens under uniaxial repeated loads. The effect of structural parameters (e.g., stirrup configuration, bond length, confinement method, and concrete cover) and loading parameters (e.g., amplitude, peak load, loading rate, and initial load cycles) on the bond properties of the reinforced concrete under repeated loads was studied in detail. In addition, the degradation mechanisms and failure modes of the specimens’ bond stress were analyzed. It is found that the use of stirrups, increase of bond length, and concrete cover, as well as confinement can effectively curb the widening and expansion of cracks in concrete and significantly improve ductility and repeated load bearing capability. As the rigidity of confinement material increased, the enhancement effect of confinement on bond stress increases. Compared to the role of confinement (e.g., carbon fiber reinforced polymer), increasing the concrete cover can more effectively improve the bond stress. The rebar's subsequent residual bond stress declines as the number of early‐stage load cycle increases.

A DFT based analysis of adsorption of Hg2+ ion on chitosan monomer and its citralidene and salicylidene derivatives: Prior to the removal of Hg toxicity

A Density functional theory based study of adsorption of the toxic metal Hg (II) ion by chitosan monomer and two of its derivatives; citralidene and salicylidene chitosan, has been performed. The effect of structural features on the stability of studied complexes has been analyzed by using Gaussian03 software package. All the possible conformations of these adsorbents were studied using the global minimum geometries. All the adsorbing sites were studied by placing the metal ion on the centroid of the atoms and the stable conformer of the adsorbent-metal ion complex was identified. Interaction between Hg (II) and the adsorbents is found to be electrostatic. Metal ion binding with nitrogen atom is stronger than that with oxygen atoms in all the cases as the charge density of nitrogen is enhanced on Schiff base formation. The advantage of derivatives over chitosan monomer is their stability in acidic media. ΔE value of the complexes are in the order SC–Hg (II)>chitosan–Hg (II)>CC–Hg (II) which indicates that the stability of complexes increases with increase in energy gap. The study reveals that aromatic Schiff base derivatives of chitosan is better for Hg(II) intake than aliphatic derivatives.

Effect of structural features in a distorting structure due to excavation-induced ground movements

This study examined the effects of structural features in a distorting structure due to excavation-induced ground movements numerically based on the justifiable comparison between a physical model test and its numerical simulation. For examining the effects of structural features this study focused on the effect of roof restraint, the effect of window opening, and the effect of grade beam on structure distortion and cracking. In this study the considered structure was block-bearing structures, in which cracking can easily be formed along block joints so that the structural response can be directly compared each other. The 2-D Universal Distinct Element Code (UDEC 3.1) was used to model the structures and examine the responses of structures. The results of numerical studies indicated that the structural features affected a structural response considerably, and therefore for more reliable assessment of the response of structures subjected to excavation-induced ground movements the effects of structural feature should be carefully evaluated and considered.

Destruction Mechanism of ZnAl4 as Cast Alloy Subjected to Cavitational Erosion Using Different Laboratory Stands

Abstract The main reason of a cavitational destruction is the mechanical action of cavitation pulses onto the material’s surface. The course of cavitation destruction process is very complex and depends on the physicochemical and structural features of a material. A resistance to cavitation destruction of the material increases with the increase of its mechanical strength, fatigue resistance as well as hardness. Nevertheless, the effect of structural features on the material’s cavitational resistance has been not fully clarified. In the present paper, the cavitation destruction of ZnAl4 as cast alloy was investigated on three laboratory stands: vibration, jet-impact and flow stands. The destruction mechanism of ZnAl4 as cast alloy subjected to cavitational erosion using various laboratory stands is shown in the present paper.