Chromate reduction by waste iron from electroplating wastewater using plug flow reactor

Waste iron was used to treat high concentration chromate (534 mg/L as Cr) from electroplating wastewater by plug flow reactor (PFR) due to the following reasons: (1) two wastes are treated simultaneously, (2) low pH of the electroplating wastewater ( approximately 2) benefits the reaction between these two wastes, (3) effluent pH is elevated in the PFR, reducing the base requirement to meet the pH discharge standard for wastewater (pH 6-9). Complete chromate reductions were achieved at pH 1.7 for hydraulic retention time (HRT) of 98 min, pH 1.5 for HRT of 40 min and pH 1.3 for HRT of 20 min. Consequently, optimum HRT for complete chromate reduction was obtained for different pHs. Although more acids were used to lower influent pH to reduce HRT, effluent pH was higher due to more hydrogen ion reacting with chromate. Eventually, fewer bases are required to fulfill the discharge pH requirement of wastewater. Effluent pH 3-5 was observed with high turbidity, indicating the precipitations of chromium oxide and hydroxide were enhanced by the dissolved iron coagulation. X-ray diffraction was conducted to examine the remaining species. Other than chromium oxide and hydroxide species, an iron-chromium complex (Cr2FeO4) was also observed.     

The prediction of the dissolution rate constant by mixing rules: the study of acetaminophen batches

The purpose of this article is to promote two simple and scalable methods to accelerate the formulation development of formulated granules using acetaminophen as a model system. In method I, formulated granules made from the batch of small particle-sized acetaminophen (1) by ball milling the batch of large particle-sized acetaminophen (2), and the mixture of the two batches at equal weights (mix) gave the dissolution rate constants (k) of k(1) = 0.43 +/- 0.15 minutes(-1), k(2) = 0.18 +/- 0.01 minutes(-1), and k(mix) = 0.30 +/- 0.03 minutes(-1) for 75 wt percent formulation; k(1) = 0.75 +/- 0.01 minutes(-1), k(2) = 0.18 +/- 0.01 minutes(-1), and k(mix) = 0.34 +/- 0.03 minutes(-1) for 62 wt percent formulation; and k(1) = 0.28 +/- 0.01 minutes(-1), k(2) = 0.16 +/- 0.01 minutes(-1), and k(mix) = 0.22 +/- 0.02 minutes(-1) for 30 wt percent formulation. In method II, the mixture of the formulated granules produced by mixing the formulated granules from the two batches at equal weights gave dissolution rate constants of k(mix) = 0.30 +/- 0.03 minutes(-1), 0.30 +/- 0.02 minutes(-1), and 0.22 +/- 0.01 minutes(-1) for 75 wt percent, 62 wt percent, and 30 wt percent formulations, respectively. After fitting the three data points of k(1), k(2), and k(mix) to the 10 mixing rules in materials science--series mixing rule, Hashin and Shtrikman upper bound, logarithmic mixing, Looyenga mixing rule, effective media approximation (EMA), three-point lower bound, Torquato approximation, three-point upper bound, Maxwell mixing rule, and parallel mixing rule--we found that the selection of the best suited mixing rules based on k(1), k(2), and k(mix) was solely dependent on the formulations under a given operating condition and regardless of whether the system was a powder mixture or a granular mixture. The values of k(1), k(2), and k(mix) in both the 75 wt percent and 30 wt percent formulations were enveloped by the parallel mixing rule and Maxwell mixing rule, whereas the values of k(1), k(2), and k(mix) for the 62 wt percent formulation were encompassed by the logarithmic mixing rule, Hashin and Shtrikman upper bound, and the series mixing rule. Apparently, the best suited mixing rules could be used to predict the right proportions of either the powder mixture (Method I) or the granular mixture (Method II) for obtaining any other desired dissolution rate constant, k(mix), whose value fell in between the values of k(1) and k(2).     

Evaluation of chitosan/β-tricalcium phosphate microspheres as a constituent to PMMA cement

Two methods, a traditional emulsion technique and a high voltage electrostatically modified encapsulation system, were used to fabricate degradable chitosan/ -tricalcium phosphate (-TCP) microspheres. The two distinct kinds of microspheres both exhibited good sphericity and the -TCP was trapped well inside the chitosan gel. The microspheres prepared by high voltage electrostatic system exhibited a rougher outer surface and narrower size distribution. These microspheres were then used as an added constituent to commercially available PMMA bone cement. Four modified cement composites that were prepared with different composition ratios of the two kinds of chitosan/-TCP microspheres that were made from emulsion technique (C1P1 and C2P1) and from a process by a high voltage electrostatic system (EC1P1 and EC2P1) were compared with the PMMA cement (Pure P). The characteristics of these materials indicate that with the addition of chitosan/ -TCP microspheres as a constituent into the PMMA cement significantly decreases the curing peak temperature. Furthermore, the setting time increases from 3.5-min to 9-min, as compared to the PMMA cement. These changes could be beneficial for the handling of the bone cement paste and causing less damage to the surrounding tissues. Understandably, the presence of chitosan/ -TCP microspheres in the prepared composites reduced the ultimate compressive strength and bending strength. From the degradation test and SEM observations, the modified chitosan/ -TCP/PMMA composites could be degraded gradually and create rougher surfaces that would be beneficial to cell adherence and growth.     

Quantification of relative gene dosage by single-base extension and high-performance liquid chromatography: application to the SMN1/SMN2 gene

One of the most commonly used techniques for genotyping of single-nucleotide polymorphism (SNP) is detection of single-base extensions (SBEs). We present a new, rapid, simple, and highly reliable method for accurate quantification of SNP variants in a single reaction. Our approach is based on SBE detection coupled with high-performance liquid chromatography (HPLC) quantification. To demonstrate the utility of our approach, we report data to determine the gene dosage for relative amounts of alleles in a homologous gene, allowing detection of mutation causing exon skipping in human SMN genes to determine the ratio between the copy numbers of the SMN1/SMN2 gene. We successfully determined the relative ratio of the SMN1 and SMN2 genes and showed assay characteristics using the SBE reaction coupled with HPLC. This assay approach readily scaled to high parallelization with multiplex SBE reactions in a single sample screened in one analysis. By screening for particular SNP genotypes, this assay can be used to determine the relative gene dosage that correlates highly with the patient's disease state. The next challenge is to apply this novel methodology in a clinical screening and quantification setting for special gene regions within highly homologous genes.     

The effects of age group,interface type,and key area of mobile phones on game playing performance,usability, and visual fatigue: A case study of a rhythm game

This study investigated the effects of age group, interface type, and key area on accuracy, usability, the change of critical fusion frequency, and subjective visual fatigue in Taiko no Tatsujin game playing. Four groups divided by age (young adult, adult, middle‐aged adult, and senior citizen), two types of interface (solid and touch), and two types of key areas (approximately 1.1 and 0.6 cm²) were investigated in the experiment. The results showed significant differences for age group on accuracy, especially for young adults and senior citizens. The solid interface demonstrated better accuracy and usability and less subjective visual fatigue than the touch interface. The approximately 1.1 cm² key indicated better performance than the 0.6 cm² key in all indexes. It is inferred that the solid interface with the 1.1 cm² key had better performance. Therefore, mobile phones with a larger key area are more suitable for game playing.     

Broadband circularly polarized Fabry‐Perot antenna utilizing Archimedean spiral radiator and multi‐layer partially reflecting surface

This article presents a method to design broadband circularly polarized (CP) Fabry‐Perot Resonator (FPR) antenna. The proposed antenna is based on multi‐layer thin dielectric slabs arranged in close proximity as a partially reflecting surface (PRS) and an Archimedean spiral as a CP radiating source. Experimental results show a broadband operation from 6 to 13 GHz, in which the reflection coefficient is less than ?10 dB and the axial ratio (AR) is lower than 3 dB. In addition, good radiation patterns and high broadside gain of better than 10.8 dBic are achieved over the operating bandwidth. The proposed antenna can be used for C‐ and X‐band satellite communications.     

Ultrawideband high‐gain dual‐polarized antenna with anti‐interference capability

In this article, a high‐gain dual‐polarized antenna with band‐rejection capability for ultrawideband (UWB) applications is proposed. Tapered dipoles are chosen as a primary radiator to achieve UWB operation and it is reflected by a metallic cavity reflector for high gain radiation. A notch at WLAN band is realized by etching a set of four bent slots in the radiating elements. The measured results demonstrate that the proposed design with overall dimensions of 0.69λ _L × 0.69λ _L × 0.16λ _L (λ _L is free‐space wavelength at the lowest operating frequency) has operating bandwidth of 95.1% (3.2‐9.0 GHz) and the rejected frequency band from 5.0 to 5.9 GHz. Additionally, good unidirectional radiation patterns with a broadside gain from 8.1 to 11.5 dBi and radiation efficiency of better than 90% are also achieved.     

The positional distribution of fatty acids in the phospholipids and triglycerides ofMycobacterium smegmatis andM. bovis BCG

Position 1 of the phospholipid and triglyceride fractions isolated fromMycobacterium smegmatis andM. bovis BCG was esterified principally with C₁₈ related fatty acids (18∶0, 18∶1 and 19Br). Position 2 was occupied principally by C₁₆ fatty acids. The third position of the triglycerides was esterified with a preponderance of C₂₀+fatty acids. Seventysix per cent of position 3 fatty acids in BCG and 43% inM. smegmatis triglycerides contained fatty acids of greater than 20 carbon atoms.