Erratum

Abstract

Abstract

The physical, physicochemical and antimicrobial properties of novel cement type calcium hydroxide/nanohydroxyapatite composites were evaluated by measuring setting time, compressive strength, phase analysis, pH, water solubility and bacterial inhibition zone. Different cement pastes were obtained by mixing biphasic powders (comprising mixtures of calcium hydroxide and nanohydroxyapatite in various weight ratios) and ester of salicylic acid as liquid. Cements with different amounts of nanohydroxyapatite set at approximately 4-14?min and had a compressive strength of 8-16?MPa. The crystalline phases of the set cements were hydroxyapatite and calcium hydroxide. Finally, all composite samples showed antibacterial activity, and the larger zone of bacterial inhibition was observed in composites with higher amount of Ca(OH)₂.     

Low-temperature phase behavior of vegetable oil/co-solvent blends as alternative diesel fuel

Vegetable oils (triacylglycerols) have many characteristics that make them attractive candidates as renewable alternative fuels for compression-ignition (diesel) engines. Unfortunately, vegetable oils are too viscous to be compatible with modern direct-injection diesel fuel systems and engines. Co-solvent blending is a simple and flexible technology that reduces viscosity by mixing the oil with low molecular weight alcohol. A co-solvent (A), consisting, of surfactant plus an amphiphilic compound, is added to solubilize otherwise nearly immiscible oil-alcohol mixtures into a single-layer (isotropic) solution. This work examines low-temperature phase behavior of two soybean oil (SBO)/methanol mixtures solubilized by A=unsaturated long-chain (C₁₈) fatty alcohol/medium-chain alkanol (n-butanol and 2-octanol), one SBO/methanol mixture solubilized by A=triethylammonium linoleate/2-octanol, and one SBO/95 wt% ethanol (E95) mixture solubilized by n-butanol. The E95-blend was further blended in 1∶1 (vol/vol) mixtures with No. 2 diesel fuel. Two types of anisotropic phase behavior were observed; formation of a cloudy layer of solid crystals suspended in bulk solution (Type 1) and formation of two immiscible liquid layers (Type II). The type of phase separation in a given solution was influenced by phase separation temperature (T _ϕ) relative to the crystallization characteristics of compounds in the SBO and fatty alcohol or amine constituents present in solution. Solutions with relatively low T _ϕ values experienced crystallization of small solid particles favoring Type 1 separations. Conversely, solutions with T _ϕ sufficient to avert crystallization of high melting point compounds favored Type II separations where T _ϕ=critical solution temperature (T _critical). Increasing the A/oil (SBO or No. 2 diesel/SBO mixture) mass ratio decreased T _ϕ while increasing the mass fraction of alcohol (methanol or E95) increased T _ϕ. This work shows that vegetable oil/A-based blends can be formulated with cold flow properties superior with respect to cloud point and comparable with respect to kinematic viscosity (v) of methyl soyate (biodiesel), either neat or blended with petroleum middle distillates. Retired     

Growth rate effect on microstructure and thermoelectric properties of melt grown Bi2Ba2Co2Ox textured ceramics

Abstract

Abstract

Bi₂Ba₂Co₂O_x thermoelectric (TE) ceramics have been grown from the melt using the laser floating zone method at different growth rates (15, 30 and 90 mm h^?1). Microstructural analysis has shown an improvement of the grain alignment and a reduction of secondary phases when the growth speed is decreased. These microstructural features have been reflected in the TE performances, with a reduction of the electrical resistivity and, as a consequence, at significant increase in the power factor values, reaching ～0·15 mW K^?2 m^?1 at 650°C for the samples grown at 15 mm h^?1, which is much higher than the typical values obtained in these materials.     

Fast switching ferroelectric liquid crystal side chain polymer

Two products were isolated at a result of esterification of acrylic acid with 4-[4-(n-hydroxyundecanyloxy)phenyl] benzoic acid (5) One is 4-[4-(n-acryloloxy-undecanyloxy)phenyl] benzoic acid (6), and the other is 4-{4-[n-(3-acryloloxy-propionyloxy)undecanyloxy]phenyl}benzoic acid (7) which containts two molecules of acrylic acid. Compound7 is obtained unexpectedly and still unknown in the literature. Its identification is confirmed by the isolation and characterization of the monomer9. The mesogenic monomers8 and9 which were synthesized from 4-hydroxyphenyl 2(S)-[2(S)-methylbutoxylpropionate (4) and the corresponding acrylates6 and7 exhibit the enentiotropic Sc* and S_A phases. The Sc^* phase temperature range is up to 31 °C. The spontaneous polarization and response time for the monomers8 and9 is 97 and 16 nC/cm² as well as 90 and 64 µs respectively. It us the liquid crystal side chain polymer11, not10, which is switchable in the presence of an electric field. The spontaneous polarization of 36 nC/cm² and the response time of 3.1 ms is obtain from the new polyacrylate.     

Third Phase Formation in the Extraction of Inorganic Acids by TBP in n‐Octane

Abstract

The extraction of HNO₃, HClO₄, H₂SO₄ and H₃PO₄ by 20% (v/v) TBP (0.73 M) in n‐octane was measured under identical conditions up to and beyond the critical point of third phase formation (Limiting Organic Concentration, or LOC condition). The data, together with those obtained previously for HCl, allowed us to establish the following lyotropic series of effectiveness with respect to third phase formation in the extraction of acids by TBP: HClO₄>H₂SO₄>HCl>H₃PO₄>HNO₃. This series correlates with the amount of water present into the organic phase at the point of phase splitting. This result reinforces the validity of the reverse micellar model developed previously for the extraction of metal salts by TBP. The measurements of LOC values as a function of temperature revealed major differences among the acid‐TBP systems investigated. For HClO₄, the strong increase of the LOC value with increasing temperatures is accompanied by a large favorable entropy change. The opposite is true for HCl, while H₂SO₄ and H₃PO₄ represent intermediate cases. Measurements of the LOC values for the extraction of HClO₄ by TBP dissolved in a series of diluents confirmed that topological parameters, such as the Connectivity Index, CI, are useful for predicting the critical condition for phase splitting in different diluents. Based on the linear correlation between LOC values for HClO₄ and CI values of diluents, the effective Connectivity Index of the French nuclear reprocessing diluent, HTP, a complex mixture of highly branched alkanes, was determined.     

Equilibrium Distribution Coefficients of Some Nitrate Impurities in Sodium Nitrate from Zone Refining

Abstract

The equilibrium distribution coefficients of 10 impurities (Li, K, Rb, Cs, Ag, TI, Mg, Ca, Sr, and Ba) in sodium nitrate were determined from the measured values of the effective distribution coefficients obtained by zone refining. The equilibrium distribution coefficients obtained are as follows: LiNO₃, 9.2 × 10^?2; KNO₃, 3.0 × 10^?1; RbNO₃, 2.2 × 10^?2; CsNO₃, 1.3 × 10^?3; AgNO₃, 7.8 × 10^?1; TlNO₃, 5.2 × 10^?1; Mg(NO₃)₂, 7.4 × 10^?2; Ca(NO₃)₂, 1.5 × 10^?2; Sr(NO₃)₂, 3.0 × 10^?2; and Ba(NO₃)₂, 2.1 × 10^?2. These values are in favorable agreement with those estimated from the phase diagrams and/or those calculated from the heat of solid solution.     

Effect of zirconia content on mechanical and thermal properties of mullite–zirconia composite

Abstract

Mullite–zirconia composites were prepared by adding various zirconia contents in the mullite ranging from 0 to 30 wt-% and sintering at 1400–1600°C for 2 h. The phase composition examined by X-ray diffraction showed that mullite was the major phase combined with developed t-ZrO₂ and m-ZrO₂ phase as a function of zirconia content, especially at 1600°C, wherein m-ZrO₂ predominated. Density increased when the zirconia content and sintering temperature were increased ranging from 2·2 to 3·53 g cm^?3. The morphology of mullite grain showed elongated grains, whereas dispersed zirconia showed equiaxed and intergranular grains. Flexural strength was continuously improved by adding zirconia during the sintering temperature ranging from 1400 to 1500°C, whereas flexural strength was initially improved up to 5 wt-% of zirconia addition and deteriorated with more than 5 wt-% of zirconia content during sintering between 1550 and 1600°C. The maximum strength, 190 MPa, was obtained when sintering mullite with 30 wt-% of zirconia content at 1500°C. The degradation of strength at high sintering temperature may be a result from more occurrence of m-ZrO₂ phase. Thermal expansion of sintered specimens indicated linear change and hysteresis loop change. The hysteresis loop obtained with increased zirconia content resulted in the t–m phase transformation. Martensitic start temperature M_s was determined to be 530°C for 15 wt-% zirconia sintered at 1500°C, implying that the t–m phase transformation occurred.     

The Synthesis and Characterization of s-Triazine-Cored and [Fe(III)Salen]-Capped Polymer Complexes

2,4,6-Trichloro-1,3,5-triazine (cyanuric chloride, C₃N₃Cl₃, 1) was used as the starting material. 2-(4-Carboxyphenylamino)-4,6-dichloro-1,3,5-triazine (2) was obtained from the reaction of cyanuric chloride with 4-aminobenzoic acid in the presence of sodium bicarbonate in acetone. A mononuclear complex (4) was obtained by reacting 2 and [FeSalen]₂O (3). A series of polymeric compounds was obtained by reacting 4 with a series of diamines. The polymeric complexes were characterized by elemental analysis, AAS, FT-IR, ¹H NMR, TGA and magnetic susceptibility measurements. The complexes are low-spin, distorted octahedral Fe(III) species that are bridged by carboxylic acids. The [FeSalen]-containing compounds may have the electronic structure t_2g⁵e_g⁰. All the complexes have six coordination and are polymeric.     

Preparation of alumina ceramic template by the molten salt method

ABSTRACT

Single-crystal alpha alumina (α-Al₂O₃) platelets were synthesised with aluminium sulphate in the study. Moreover, the effects of the heating temperature, holding time, and different power mixtures of γ-Al₂O₃ and sodium sulphate (Na₂SO₄) on the morphology of as-prepared α-Al₂O₃ platelets were explored. The crystalline phase evolution and morphology of the samples were characterised by X-ray diffraction and scanning electron microscopy. According to the further analysis results, most of α-Al₂O₃ platelets were hexagonal particles. After the power mixture of γ-Al₂O₃ and Na₂SO₄ (1:2) was heated at 1200°C for 1?h, the platelet size became relatively uniform with an average diameter of 3–5?μm and a thickness of 50–100?nm. This method is an easily controllable, simple, and green method to produce high-quality α-Al₂O₃ platelets.     

A convenient synthesis of alkyl-2-(2-imino-4-oxothiazolidin-5-ylidene)acetate derivatives involving an electrogenerated base of acetonitrile

We report a simple method for the synthesis of alkyl-2-(2-imino-4-oxothiazolidin-5-ylidene) acetate derivatives 3 in good yields under mild conditions. The electrogenerated cyanomethyl base (EGB), obtained from electroreduction of acetonitrile-0.1?M TBABF₄, assists the reaction between thiourea derivatives 1 and dialkyl acetylene dicarboxylate 2. The expected products, 3/4, and the structure obtained from X-ray diffraction confirm that the main products are the five-membered heterocycles 3. Furthermore, a mechanism, to explain the reaction pathways, is proposed based on the thermodynamic and kinetic data obtained from quantum calculations.     

Eddy Diffusion and Zone Spread in Paper Chromatography

Abstract

A velocity-independent plate-height term comparable to eddy diffusion has been described for paper chromatography. This term couples with nonequilibrium lateral diffusion and is a major contribution to zone spreading at high solvent velocities. A mechanism is proposed based on random variations in R_f values caused by the inhomogeneous structure of paper. On theoretical and experimental bases it is demonstrated that maximum resolution in paper chromatography can be obtained by control of solvent velocities to values near 1 ± 10^?3 cm/sec.     

Comparison between Personal and Individual Exposure to Urban Air Pollutants

This study tested the reliability of a novel method developed for assessing the individual exposure to size-fractionated particulate matter (PM) and gaseous urban pollutants. Individual exposure was defined as the exposure constantly measured in proximity to the subject, even during transfers.

Individual exposure was measured using a mobile monitoring unit (MMU), developed to sample simultaneously some urban pollutants of interest for public health purposes. The obtained concentrations were compared with those simultaneously collected in the breathing zone, considered as the gold standard for estimating human exposure to air pollutants.

Short-time number concentrations of ultrafine, fine, and coarse particles collected by MMU were characterized by a high predictivity of personal exposures (R ² ≥ 0.89; slope 0.94–1.17 for PM < 10 μ m), far superior to fixed-site measurements. 5-h time-weighted averages fully explained the variability of ultrafine and fine particles (R ² > 0.99).

The concentrations of gaseous pollutants measured by MMU were less correlated with those collected in the breathing zone (R ² = 0.34–0.65). Nevertheless, the capability of the MMU to detect the variations of personal exposures to O ₃ and CO was better than that normally observed using fixed measurements, likely due to the placement of the MMU in the different microenvironments where subjects spent their time.

Individual exposures measured by the MMU could be of importance in toxicological and epidemiological studies on PM, with the advantage of accounting for exposure to several gaseous co-pollutants.     

Structural characterization of three organically modified Cd(II) compounds

Based on a strategy of introducing the inorganic SCN⁻ group into CdX₂-organoamine system, three organically modified Cd(II) compounds as 1-D [H₂dmpip][CdCl₃(SCN)] (dmpip = N,N´-Dimethylpiperazine) 1, 2-D [Cd(SCN)₂(dach)] (dach = 1,4-Diazacycloheptane) 2 and mononuclear [CdI₃(Hdach)] 3 were obtained in H₂O/C₂H₅OH solutions under ambient conditions. X-ray single-crystal diffraction analysis revealed that compound 1 is diprotonated dmpip-templated chained cadmium-chloro thiocyanate, compound 2 is the first example of dach-extended layered cadmium-thiocyanato coordination polymer, and compound 3 is monoprotonated dach-coordinated mononuclear cadmium iodide. The photoluminescence analysis indicates that the title three compounds are the potential fluorescence materials.     

Sintering Rates for Pristine and Doped Titanium Dioxide Determined Using a Tandem Differential Mobility Analyzer System

Sintering rates of pristine and V-doped TiO ₂ were obtained using a tandem DMA system. A range of experiments were conducted to first map out the variation of mobility size of a monodisperse (by mobility) agglomerate with time at three fixed temperatures. Using relationships of the surface area to the mobility size, the sintering equation was solved to determine the activation energy and pre-exponential factor. The value of the activation energy was 236 (± 46) kJ/mol for pristine TiO ₂ and 363 (± 1) kJ/mol for V-doped TiO ₂ . The corresponding pre-exponential factors were 7.22 × 10 ¹⁹ and 2.22 × 10 ¹² s/m ⁴ K, respectively. These values were then used to predict changes in mobility diameter at different temperatures, and good agreement was obtained with measurements. Possible reasons for faster sintering rates of V-TiO ₂ relative to pristine TiO ₂ were conjectured.     

Synthesis of linear polysiloxanes with electron-donating organophosphorus pendant groups by kinetically controlled ring-opening polymerization

Six-membered ring siloxane monomers containing a phosphorus electron-donating groupR=–CH₂CH₂PPh₂ (1), –CH₂CH₂P(S)Ph₂ (2), and –CH₂CH₂P(O)Ph₂ (3) were synthesized. The anionic ring-opening polymerization of these monomers with kinetic control of products has been studied using tetrahydrofuran (THF) as solvent and lithium silanolates as initiators. The polymerization leads to a high molecular weight linear polymer with a very good yield in the case of2 and with a fairly good yield in the case of1 and3. The presence of the phosphorus group enhances the cyclization and broadens the molecular weight distribution of the linear polymer. This effect is relatively weak for the thiophosphinoyl group. At least in the case of the polymer obtained from2, phosphorus groups are distributed uniformly in the macromolecule, however, their arrangement along the chain is not regular. The interaction of polymers obtained from monomers1, 2, and3 with some electrophiles such as alkyl or silyl halides was demonstrated to lead to generation of polyelectrolytes.     

Comprehensive Studies on Third Phase Formation: Application to U(VI)/Th(IV) Mixtures Extracted by TBP in N-dodecane

ABSTRACT

Phase splitting of tributylphosphate (TBP)/n-dodecane organic phases resulting from the extraction of UO₂(NO₃)₂, Th(NO₃)₄ and mixtures of both actinides from aqueous nitrate solutions has been investigated. Limiting organic concentrations (LOC) and metals distribution beyond third phase formation have been determined, with comparison between the cases of single metal-systems and metals mixtures. Simultaneous quantification of TBP and both metals was achieved through X-ray fluorescence (XRF) analyses. LOC studies reveal that thorium (IV) drives the third phase formation as it is the most destabilizing element in the solvent. After organic phase splitting, studies of the distributions of metals between the heavy organic phase (HOP) and the diluted organic phase (DOP) in the case of U^(VI)/Th^(IV) mixtures revealed that they are similar to those observed when both metals are alone in the solvent: Thorium (IV) has a strong affinity for the HOP, whereas uranium (VI) distributes both in HOP and in DOP. A supersaturation coefficient (N_LOC) is proposed as a new tool to account for the data obtained in the present study. Furthermore, the approach was successfully applied to analyse available data in the literature regarding thorium (IV) distribution studies after phase splitting in various TBP-alkane solvents. Such a study beyond third phase formation paves the way for studying the mechanism involved in third phase formation, as the metal is clearly identified as the key parameter.     

Effect of Coordinating Solvents on Solution Speciation and the Crystallisation via ROP of a Triphos-Silver Coordination Cage

There is a general lack of understanding of how coordination polymers (metal-organic frameworks) form. Some insight can be gained from observations of formal ROP (ring-opening polymerisation) relationships between coordination polymers and their discrete soluble precursors. Most ROP examples reported previously have involved bidentate bridging ligands. Here we present an unusual example of a ROP relationship based on a tripodal ligand. In particular, 1,3,5-tris(diphenylphosphino)benzene (L1) is found to form a symmetrical coordination cage of stoichiometry Ag₃(L1)₂ in solution in acetonitrile. This contrasts with previous observations in less-coordinating solvents in which higher nuclearity cages are also formed, and shows that the coordinating acetonitrile solvent reduces anion-templating effects. On crystallization from acetonitrile a one-dimensional polymeric structure [Ag₃(L1)₂(NCCH₃)(OTf)₃] _n is obtained. The structure is noteworthy in being a ROP isomer of the trinuclear cage observed in solution. The structure also exhibits solvent-filled channels (maximum diameter 6.1 Å) but the material is not stable to desolvation. The structure of the polymer contrasts with that obtained from less-coordinating solvents, the latter being a stable hexagonal 2-dimensional structure with nanoporosity.     

Palladium (0) catalyzed Suzuki cross-coupling reactions of 2,4-dibromothiophene: selectivity,characterization and biological applications

A series of novel 2-aryl¹-4-bromothiophenes (2a–f), biarylthiophenes with non-identical aryl groups (3a–e) and biarylthiophenes with identical aryl groups (4a–f) were synthesized in moderate to excellent yields by using different arylboronic acids in a Suzuki–Miyaura cross-coupling reaction. The experimental results showed that the use of K₂CO₃ as base resulted in moderate yields compared with that of good yields obtained upon using K₃PO₄. The highest yield obtained using K₃PO₄ was 82% for 2, 4-bis (4-chlorophenyl) thiophene (4d). The synthesized compounds in the present study were examined for their biofilm inhibition and hemolysis assay. Among all compounds 2, 4-bis (4-methoxyphenyl) thiophene (4b) was found to strongly inhibit the formation of bacterial biofilm against E. coli. The compound 4b exhibited higher inhibition (80.92%) compared with the standard Rifampicin with 97.43% inhibition. The compound 2, 4-bis (4-chlorophenyl) thiophene (4d) displayed strong anti-biofilm activity with its ability to prevent the formation of Pasteurell amultocida biofilm at the percent inhibition of 74.53%. In addition, 2f showed the highest percentage hemolysis 16.0% compared with that of the standard Triton-X-100. 3     

Study of phase behavior and Congo red dye partitioning in aqueous two-phase systems composed of hydrophilic alcohols (1-propanol/ 1-butanol) and sodium salts

ABSTRACT

The partitioning of the Congo red dye in ATPSs formed by alcohols (1-butanol, 1-propanol)/sodium salts was considered. Binodal and the LLE data were experimentally determined at 298.15 K. The salting-out abilities of the salts follow the order Na₃C₆H₅O₇ > NaH₂PO₄ > C₂H₃ O₂Na. The phase-forming abilities of the alcohols follow the order: 1-butanol > 1-propanol. The four-parameter equation was applied to correlate the binodal curves data. Therefore, The Bancroft and Othmer-Tobias equations were used to prove the reliability of the corresponding LLE data. ATPS composed of 6.5% of 1-butanol and 20% of Na₃C₆H₅O₇ had the highest values of extraction by the yield of 98.54%.