A City for Education

Ameena Ahmadi is Architecture Manager at the Qatar Foundation, overseeing the development of the masterplan and facilities of Education City in Doha, a multi-institution educational campus, incorporating schools and universities. Ahmadi describes how education is a significant cornerstone for Qatar's national transition ‘to a knowledge-based’ economy from a ‘hydrocarbon-based’ one. This is symbolised by substantial investment in the flagship Education City with its Arata Isozaki masterplan and its individual schools and universities designed by premier international architects.     

AOS、LAS复配洗涤剂粘度对温度敏感性的影响

采用阿累尼乌斯方程描述了AOS、LAS复配液体洗涤剂粘度与温度的变化关系．实验结果表明，随体系中AOS含量的增加，体系表观活化能的绝对值减小，体系粘度对温度的敏感性降低。     

Effect of laundry activities on in-stream concentrations of linear alkylbenzene sulfonate in a small rural South African river

In many parts of the world clothes are washed near to or in rivers and streams. Little information is available on resulting concentrations of detergent ingredients or on any potential effects caused. In this study, the fate of a commonly used anionic surfactant, linear alkylbenzene sulphonate (LAS) was investigated in a reach of the Balfour River (Eastern Cape Province, South Africa) which was regularly used as a site for laundry activity. Samples of river water were collected upstream of the main washing site and at a number of locations downstream on several occasions in winter and summer. Sediment samples were also collected and analysed. In addition, a household survey was conducted to ascertain the amount of detergent used and the distribution of washing practices. The results of the survey suggested that the use of riverside locations for laundry activities was seasonal. Most washing tended to be done at home during the winter with riverside sites used more frequently during the summer months. The monitoring data showed that LAS concentrations in water were very variable. They were occasionally high in the immediate vicinity of the laundry site (up to 342 µg L^− 1) but were generally very low (< 11 µg L^− 1) at downstream monitoring stations, suggesting that LAS was rapidly dissipated by a combination of degradation, hydrodynamic dispersion and dilution. Concentrations in the immediate vicinity of the washing site were lower than expected on the basis of the household survey because most waste water was disposed of on the river bank rather than directly in the river. No ecological effects are expected from LAS emissions at this site.     

Effects of OH− anion additive concentration in nitrate salt baths on chemical strengthening of Li2O–Al2O3–SiO2 (LAS) glass

Two ion-exchange processes of K⁺-Na⁺ and Na⁺-Li⁺ were used to strengthen LAS glass materials, and the effects of OH⁻ anion additive (introduced by hydroxide additive) in molten salt baths were investigated. The K⁺-Na⁺ ion-exchange was superior than Na⁺-Li⁺ ion-exchange in the strength enhancement, and with the hydroxide additive, the thickness of ion-exchange layer, the ion-exchange rate and the flexural strength of LAS glass specimens were enhanced remarkably. In detail, for two ion-exchange processes, the optimized ion-exchange time decreased from 24 h to 2 h and from 6 h to 1 h, and the thickness of ion-exchange layer increased from 16 μm to 22 μm and from 23 μm to 34 μm, respectively. Consequently, the corresponding optimized flexural strength increased from 360 MPa to 520 MPa and from 270 MPa to 460 MPa, attributing to the increased thickness of ion-exchange layer and the increased concentration of alkali ions. It is believed that the broken chemical bonds along with the depolymerized glass network induced by OH⁻ anion decreased the diffusion activation energy E_a and increased the diffusion coefficient D of alkali ions for ion-exchange, and thereby the chemical strengthening process of LAS glass materials was improved.     

强化吸附性生物膜处理洗浴废水实验研究

通过纯种分离获得LAS优势降解菌,以活性炭纤维为载体挂膜形成强化吸附性生物膜进行洗浴废水处理实验研究;并在动态实验条件下,与单纯活性炭吸附和普通吸附性生物膜处理工艺进行了对比。实验结果表明:在相同的反应条件下,强化吸附性生物膜对LAS、COD的去除率比普通吸附性生物膜高7.63%和4.2%;当进水流量为1.5 L/h,HRT为4 h,曝气量为1.5 mg/L时,其对洗浴废水中LAS、COD和NH3-N的去除率分别为87.14%、85.87%和74.89%。     

Sulfoxylated methyl esters as potential components of liquid formulations

Sulfoxylated methyl esters (Φ-MES) are obtained via sulfoxidation of fatty acid methyl esters with SO₂, O₂, and ultraviolet light of appropriate wavelength. These products may be used as co-surfactants with linear alkylbenzene sulfonate and alkyl ether sulfate, either in heavy-duty or in hand dishwashing liquids. Standard hand dishwashing formulations based on Φ-MESC₁₆ are presented and discussed with regard to solubility, viscosity, performance, and skin compatibility. The experimental results obtained indicate that the above-mentioned products can be regarded as potential components for liquid formulations.     

烷基苯磺酸钠在环境中自然降解的研究进展

烷基苯磺酸钠(LAS)在环境中的自然降解行为一直是环境保护界研究的重点.阐述了LAS在环境(水体、土壤)中的自然降解过程及降解机理,分析了LAS的分子结构、初始浓度及环境中微生物数量、温度、供养量、pH值等主要因素对LAS降解效率的影响,以期为LAS的扩大应用及其污染治理提供参考和依据.     

Exposure of the marine deposit feeder Hydrobia ulvae to sediment spiked with LAS congeners

The lethal and sub-lethal toxicity of LAS congeners to the mollusc gastropod Hydrobia ulvae were assessed in spiked sediment bioassays. This complements the little knowledge available to date on mixture effects in the sediment compartment. The LAS homologues joint effect was concentration additive (∑TU_i = 0.8-1). As opposed to the 10-d LC10 based on the sediment associated LAS concentration (91-330 mg/kg) which was independent of the homologue chain length, the LC10 based on the dissolved LAS fraction (0.804-0.068 mg/L) decreased as the homologue chain length increased from 10 to 13 carbons. The quantitative structure-activity relationship (QSAR) derived from these data was log (1/LC10 (mol/L)) = 0.64 log K_ow + 4.40 (n = 5; r² = 0.76; s = 0.24). It showed an apparent higher toxicity compared to the typical QSAR for polar narcosis in water-only systems probably due to the simultaneous exposure of the snail to LAS through the dissolved and the sediment associated fractions. The egestion rate of the surviving snails recovered after few days' exposure (1-d NOEC: 40-107 mg/kg, 9-d NOEC: 65-190 mg/kg) which suggests that the organisms were able to acclimate to LAS during the exposure.     

Using sonochemical reactor for degradation of LAS from effluent of wastewater treatment plant

Linear alkylbenzene sulfonates (LAS) are anionic surfactants, which are found in relatively high amounts in domestic and industrial wastewaters. The effectiveness of using sonochemical reactor for the degradation of LAS from effluent of wastewater treatment plant has been investigated. In this study, experiments of LAS solution were performed using methylene blue active substances (MBAS) method. The effectiveness of sonochemical reactor for LAS degradation is evaluated with emphasis on the effect of sonication time and initial LAS concentration. Experiments were carried out at initial concentrations of 0.2 mg/L, 0.5 mg/L, 0.8 mg/L and 1 mg/L, frequency of 130 kHz, acoustic power value of 400 W, temperature of 18-20 °C and pH value of 6.8-7. This study showed that LAS degradation was found to increase with increasing sonication time. In addition, as the concentration is increased, the LAS degradation rate decreases in the sonochemical reactor.     

High temperature flow behaviour of SiC reinforced lithium aluminosilicate composites

The compressive flow behaviour of lithium aluminosilicate (LAS) glass, with and without SiC particulate reinforcements, was studied. The LAS glass crystallized toβ spodumene during high-temperature testing. The flow behaviour of LAS glass changed from Newtonian to non-Newtonian due to the presence of crystalline phase. Further, with the addition of 40 vol.% SiC additions, the strain rate sensitivity of flow stress decreased. While the activation energy for flow in LAS was 300 kJ/mole, it increased to 995 kJ/mole with the addition of 40 vol.% SiC reinforcements.