The stability of dye dispersions in the presence of ethoxylated sorbitan lauryl and oleyl esters were reported and compared with dye dispersions containing a conventional dispersing agent, i.e. naphthalene sulfonic acid methylene-bis sodium salt (NSAB). The optimum operating conditions obtained using a central composite design and stability of dye dispersions were evaluated by a turbidimetry method. Results showed that the dose of surfactants and the temperature of operation were important factors in preparing stable dye dispersions. Also, the best conditions for preparing dye dispersions were as follows: dose of surfactant 0.05 g, temperature 25 °C and time 5 min. In addition to, findings indicated that both of the used surfactants had better performance in dispersing the dyes in water. However, ethoxylated sorbitan oleate had better efficiency relative to other used dispersing agents. The performance of both sorbitan esters were compared with NSAB. The results indicated that they can create stable dye dispersions in aqueous media and have approximately the same effectiveness with NSAB. In this series, although oleate ester had a better performance than the laurate, the difference in performance of using dispersing agents was not significant. This finding was confirmed by the results of the particle size analysis of dye dispersions. 相似文献
Many studies have been conducted to study the various polymorphs and morphologies of calcium carbonate crystals in nature and living organisms. In this experimental work, a novel method has been employed to crystallize calcium carbonate by using colloidal gas aphron dispersion. The polymorph and morphology of prepared particles were investigated using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectrometry techniques. SEM and XRD analyses demonstrated that the morphology of synthesized CaCO3 can be changed from spherical (vaterite phase) to novel rod and plate-like shapes (mixture of vaterite and calcite phases) with changes in the surfactant concentration. The quantitative examination results of different calcium carbonate polymorph orientations showed that the precursor concentrations had no significant effect on the orientation of calcite phase, but rather they affected the orientation development of vaterite phase at a higher surfactant concentration. 相似文献
Carbohydrate-based vinyl acetals (5-hex-enopyranosides) undergo reductive rearrangement with triisobutylaluminum (TIBAL) to afford highly functionalized cyclohexanes in which both the aglycon and anomeric stereochemistry are retained. Here, we report the first application of this process to the rearrangement of hex-5-enopyranosides of sucrose in which the interglycosidic oxygen atom of the vinyl acetal system links the anomeric centers of both monosaccharide units. The sucrose-derived 5-hex-enopyranoside 1 undergoes smooth reductive rearrangement with TIBAL to afford the (1 → 2′) ether-linked pseudo-disaccharide 2 in 34% yield. The rearrangement is accompanied by some loss of stereochemical integrity at C-2′ due to a competitive exo-cleavage of the interglycosidic (O-C2′) bond, hence diastereomers at C-2′ are also obtained in 12% yield. The 4-O-allyl-protected sucrose-5-ene 3 is similarly transformed into the corresponding (1 → 2′) ether-linked pseudo-disaccharide 4 , illustrating the compatibility of the allyl group with the TIBAL reaction conditions. 相似文献
Reactive plasma spray of TiN ceramic coating attracts much attention over the years because of its ability to deposit thick layers on various metal surfaces. However, some mechanical properties of the coating such as its hardness should be improved. In this study, initially a thin layer of titanium nitride was prepared on a titanium substrate during irradiation of titanium substrate by a thermal DC nitrogen-contained plasma jet. Then, during reactive plasma spraying, Ti particles were injected into plasma jet, converted to titanium nitride and huddled on to the substrate. This new hybrid method (primary plasma irradiation and post-reactive plasma spraying) for deposition of TiN coatings would combine the advantages of both plasma-enhanced chemical vapor deposition and reactive plasma spraying methods in part. It resulted in a thick and hard layer of titanium nitride film. Sample produced by this method was analyzed with x-ray diffraction confirming titanium nitride production. Vickers hardness was measured using optical microscopy which was around 1319 Hv300g. To study the cross section of the layer, optical microscopy and scanning electron microscopy (SEM) were used. 相似文献
Here, means to enhance power conversion efficiency (PCE or η) in bulk‐heterojunction (BHJ) organic photovoltaic (OPV) cells by optimizing the series resistance (Rs)—also known as the cell internal resistance—are studied. It is shown that current state‐of‐the‐art BHJ OPVs are approaching the limit for which efficiency can be improved via Rs reduction alone. This evaluation addresses OPVs based on a poly(3‐hexylthiophene):6,6‐phenyl C61‐butyric acid methyl ester (P3HT:PCBM) active layer, as well as future high‐efficiency OPVs (η > 10%). A diode‐based modeling approach is used to assess changes in Rs. Given that typical published P3HT:PCBM test cells have relatively small areas (~0.1 cm2), the analysis is extended to consider efficiency losses for larger area cells and shows that the transparent anode conductivity is then the dominant materials parameter affecting Rs efficiency losses. A model is developed that uses cell sizes and anode conductivities to predict current–voltage response as a function of resistive losses. The results show that the losses due to Rs remain minimal until relatively large cell areas (>0.1 cm2) are employed. Finally, Rs effects on a projected high‐efficiency OPV scenario are assessed, based on the goal of cell efficiencies >10%. Here, Rs optimization effects remain modest; however, there are now more pronounced losses due to cell size, and it is shown how these losses can be mitigated by using higher conductivity anodes. 相似文献
An approach to spectral analysis of the energy-band-structure parameters (bandgap width and Urbach energy) of potassium polytitanate (PPT) nanoparticles modified by transition metals is proposed, which can provide a basis for the synthesis of new photocatalytic materials. It is established that the modified PPT samples are characterized by reduced values of the bandgap width and higher values of the Urbach energy as compared to the initial material. Possible mechanisms of this phenomenon are discussed. 相似文献
Fars province is a large populated large province located in the southwest of Iran. This work presents a study of natural and radioactivity levels in soil samples of this province. For this purpose, 126 samples were gathered from different regions of the province and analysed by gamma spectroscopy to quantify radioactivity concentrations of radionuclides using a high-purity germanium detector and spectroscopy system. The results of this investigation show the average concentrations of 271 ± 28 Bq kg(-1), 6.37 ± 0.5 Bq kg(-1), 14.9 ± 0.9 Bq kg(-1) and 26.3 ± 1.9 Bq kg(-1) for (40)K, (137)Cs, (232)Th and (238)U in soil, respectively. Finally, baseline maps were established for the concentrations of each of the radionuclides in different regions. The absorbed dose rate and the annual effective dose (AED) were also calculated for the radionuclides according to the guidelines of UNSCEAR 2000. The average AED from the radioactivity content of soil in this province was found to be 39.9 ± 1.8 μSv. 相似文献
Eukaryotic elongation factor 2 (eEF-2) can undergo ADP-ribosylation in the absence of diphtheria toxin. The binding of free ADP-ribose and endogenous transferase-dependent ADP-ribosylation were distinct reactions for eEF-2, as indicated by different findings. Incubation of eEF-2 tryptic fragment 32/33 kDa (32F) with NAD was ADP-ribosylated and gave rise to the covalent binding of ADP-ribose to eEF-2. 32F was revealed to be at the C-terminal by Edman degradation sequence analysis. In our study, the elution of 32F from SDS-PAGE was ADP-ribosylated both in the presence and absence of diphtheria toxin. These results suggest that endogenous ADP-ribosylation of 32F might be related to protein synthesis. This modification appears to be important for the cell function. 相似文献