Use of a mathematical model in the analysis of survival curves of Daphnia magna exposed to toxicants

Chronic toxicity tests carried out on species of the genus Daphnia (Crustacea: Cladocera) are bioassays commonly used in ecotoxicology. Mortality in the cohorts exposed to toxicants can be examined by the analysis of survival curves. The shape of these curves may be very different because of inter-individual heterogeneity: the less rectangular is the shape the more different is the probability of dying of daphnids in the cohort. Aim of this paper is to analyze the characteristics-in particular the shape-of survival curves of cohorts of Daphnia magna exposed to heavy metals in chronic toxicity tests. Experimental curves were fitted by a mathematical model recently proposed, which puts emphasis just on this heterogeneity, described by the parameter of the model S(0). The information contained in S(0) is very useful for the present purposes: the higher the value of S(0) the less rectangular the shape of the curve and, as a consequence, the higher the age-at-death heterogeneity of the cohort is thought to be. The model contains a second parameter, omega, representing the maximum potential ability of the individuals to survive in a specific environment and is related with the maximal life span. The model fitted well the survival curves in most cases and both S(0) and omega showed statistically different values between treatments, useful for comparisons. It was concluded that S(0) provides a quantitative estimation of curve "rectangularization", useful to check different sensitivities to a specific toxicant concentration among daphnids belonging to the same cohort, while omega provides an estimate of maximal life span.     

Chronic toxicity of hydrogen peroxide to Daphnia magna in a continuous exposure, flow-through test system

A flow-through, continuous exposure test system was developed to expose Daphnia magna to an unstable compound. 35% Perox-Aid is a specially formulated hydrogen peroxide (a highly oxidative chemical) product approved for use in U.S. aquaculture and therefore has the potential to be released from aquaculture facilities and pose a risk to aquatic invertebrates. The study objective was to assess the effects of 35% Perox-Aid on an aquatic invertebrate by evaluating the survival, growth, production, and gender ratio of progeny from a representative aquatic invertebrate continuously exposed to 35% Perox-Aid. The study design consisted of 6 treatment groups (10 test chambers each) with target hydrogen peroxide concentrations of 0.0, 0.32, 0.63, 1.25, 2.5, and 5.0 mg L(-1). The study was initiated with <24-h-old Daphnia (1 daphnid per chamber) that were exposed to hydrogen peroxide for 21 days. Hydrogen peroxide concentrations < or =1.25 mg L(-1) had no significant effect on Daphnia time to death compared to controls and no significant effect on the time to first brood production and the number of broods produced. Concentrations < or =0.63 mg L(-1) had no significant effect on the total number of young produced. Concentrations > or =0.32 mg L(-1) had a negative effect on Daphnia growth. Hydrogen peroxide had no significant effect on the gender ratio of young produced. All second generation Daphnia were female. A continuous discharge of hydrogen peroxide into aquatic ecosystems is not likely to affect cladocerans if the concentration is maintained at < or =0.63 mg L(-1) for less than 21 days.     

灌砂法检测路基压实度技术要点探讨

介绍了灌砂法的基本原理及适用范围,对量砂的选择与标定进行了研究,从选点及检测频率、试坑开挖、含水率测定等方面提出了灌砂法检测路基压实度的技术要点,以达到提高测试结果精度的目的。     

反射波法检测水泥搅拌桩的应用

结合工程实例,对反射波法应用于水泥搅拌桩的理论基础、可行性、实际应用与可靠性进行了分析,指出只要选择合理,处理得当,在满足一定的条件下,利用反射波法检测水泥搅拌桩的桩身完整性是可行的,同时对反射波法检测水泥搅拌桩的局限性进行了探讨.     

Development of a method to relate the moisture content of a building material to its water activity

Subjective indicators of building dampness consistently have been linked to health, but they are, at best, semi‐quantitative, and objective and quantitative assessments of dampness are also needed to study dampness‐related health effects. Investigators can readily and non‐destructively measure the “moisture content” (MC) of building materials with hand‐held moisture meters. However, MC does not indicate the amount of the water in a material that is available to microorganisms for growth, that is, the “water activity” (A_w). Unfortunately, A_w has not been readily measurable in the field and is not relatable to MC unless previously determined experimentally, because for the same moisture meter reading, A_w can differ across materials as well as during moisture adsorption vs desorption. To determine the A_ws that correspond to MC levels, stable air relative humidities were generated in a glove box above saturated, aqueous salt solutions, and the A_w of gypsum board and the relative humidity of the chamber air were tracked until they reached equilibrium. Strong correlations were observed between meter readings and gravimetrically determined MC (r=.91‐1.00), among readings with three moisture meters (r=.87‐.98), and between meter readings and gypsum board A_w (r=.77‐.99).     

用低应变反射波法检测搅拌桩桩身完整性探讨

结合反射波法的基本原理,阐述了低应变反射波法检测搅拌桩的方法,并对水泥土搅拌桩桩身完整性检测方面进行分析,最后得出低应变反射波法检测水泥土搅拌桩还处于探索阶段,还需继续进行探讨的结论。     

Effects of humus concentrations on benzo[a]pyrene accumulation from water to Daphnia magna: comparison of natural waters and standard preparations

The bioaccumulation of benzo[a]pyrene (BaP) into Daphnia magna from two natural humic waters (one lake water and one bog water), and two humus preparations (Nordic Reference fulvic acid (Nordic FA) and a lyophilized concentrate) of the same aquatic origin was measured by using several dissolved organic carbon (DOC) concentrations for each sample. The partition coefficient (Kp) of BaP to the humus content of the water was determined by an equilibrium dialysis technique. In all four samples, an increase in humus concentration decreased the bioavailability of BaP in a logarithmic manner. The Nordic FA and the natural untreated humic water, from the same source as the water used for isolation of Nordic FA, gave a similar DOC bioaccumulation response and similar Kp values. The difference between the two natural humic waters was obvious, both in the accumulation experiments and the Kp values. The assumption that the total bound fraction of organic pollutant is not available for D. magna is not fully supported by this study.     

新型冷计量收费装置开发及计费策略分析

介绍了焓差法冷量计量装置的原理和特点,对冷量计费进行了成本分析,并指出实际应用中影响计费的因素,预测了这种新型冷计量装置的市场及发展前景。     

一种桥梁挠度精密监测新方法的研究

在现代测量领域内,测量仪器选择的依据和测量项目精度要求有关,项目精度要求越高预示着对测量仪器的精度指标要求越高。如何利用常规仪器完成高精度要求的项目是测量界一直关心的难题。本文以桥梁挠度监测为例,提出一种新的实时监测方法,并从理论和试验模拟证明了该方法的可行性。为今后类似工程方案设计的制作提供新的思路,具有一定的现实指导意义和应用价值。     

Development of a new method for RMR and Q classification method to optimize support system in tunneling

Rock mass classification system is very suitable for various engineering design and stability analysis. JH classification method is confirmed by Japan Highway Public Corporation that this method can figure out either strength or deformability of rock mass, further appropriating the amount of rock bolts, thickness of shotcrete, and size of pitch of steel ribs just after the blasting procedure. Based on these advantages of JH method, in this study, according to data of five deep and long tunnels in Iran, two equations for estimating the value of JH method from Q and RMR classification systems were developed. These equations as a new method were able to optimize the support system for Q and RMR classification systems. From JH classification and its application in these case studies, it is pointed out that the JH method for the design of support systems in underground working is more reliable than the Q and RMR classification systems.     

关于混凝土灌注桩桩身完整性检测方法的探讨

通过低应变反射波法、声波透射法（超声波法）、钻芯法检测结果相互对比的探讨,说明混凝土灌注桩桩身完整性检测综合运用上述检测方法的必要性。     

Development of a method to predict the heat island potential using remote sensing and GIS data

Most studies directed to urban climate simulation have been carried out under the assumption that an urban canopy layer is a sublayer comprised of various roughnesses, and as a consequence, difficulties have arisen in obtaining a suitable heat balance for such a layer. This paper, therefore, focuses on investigating the surface temperature distributions of all urban surfaces via a new index based on sensible heat flux, named the heat island potential (HIP), which can be employed in urban development planning to evaluate the urban thermal environment. Simulation results following the use of HIP are verified by side-looking airborne multi-spectral scanner (MSS) and geographic information system (GIS) data; thereby enabling elucidation of these thermal effects on the atmosphere. In addition, a heat balance algorithm is developed which simulates urban surfaces such that construction of urban thermal images is possible.     

Development of a new laboratory evaporation measurement device as decision support for evaporation-optimized building

A new laboratory evaporation measurement device (LEMD) was developed to estimate the evaporation rates of urban surface materials. Here, evaporation is induced by means of a constant heat input and airflow. The evaporation can be measured using two different methods concurrently. Method 1 is based on a balance, which measures the mass loss over time. In method 2 the water vapour transport in the air is measured by humidity sensors thus enabling the calculation of the evaporation rate. Test measurements show a sensitivity of method 2 against influences from the environment, therefore, method 1 was used for subsequent measurements. With the assistance of the LEMD, an estimation of the evaporation rates for different materials was determined within a short period of time and with low costs.     

Development of a smart city planning support tool using the cooperative method

A reduction of environmental burdens is currently required. In particular, proposing a new approach for the construction of a smart city using renewable energy is important. The technological development of a smart city is founded building equipment and infrastructure. However, planning methods and their techniques using the collaboration approach with residents are only just developing. This study aimed to develop a support tool for the construction of a smart city using renewable energy while facilitating consensus-building efforts among residents using the method for a cooperative housing development. We organized the supporting methods for the construction of residential area using the cooperative method. Then, we developed supporting tools that interface the computer with these methods. We examined the support techniques for the construction of a residential area using renewable energy technology by analyzing Japanese cases of a smart city. Moreover, we developed a support tool for the construction of a smart city on a trial basis. We integrated the smart city construction tools and the cooperative housing construction support tool. This tool has a 3D modeling system that helps residents to easily understand the space image as a result of the examination. We also developed a professional supporting tool that residents can consider for cost-effectiveness in renewable energy and its environmental load reduction rate for the planning of a smart city.     

高密度电法探测未知目标体的技术及其效果

高密度电阻率法在各个领域得到了广泛的应用,并取得了良好的效果。本文主要说明了高密度电阻率法探测地下未知目标体的工作方法和各种可能遇到的问题及解决方案,包括线路连接,测线布置等方面,以及资料处理的细节问题。高密度电法不同装置具有不同的特点,这里结合高密度电阻率法数据采集过程中的各种因素进行了综合阐述,通过实例说明了高密度电法探测未知目标体的装置特点及其适用领域。     

Measurement of biomass activity in drinking water biofilters using a respirometric method

A simple respirometric method was developed and applied for the measurement of biomass activity in bench-scale drinking water biofilters. The results obtained with the new method, i.e. biomass respiration potential (BRP), indicated a high sensitivity allowing the quantification of the activity of low amounts of biomass. The analysis of duplicate samples showed a reasonable reproducibility, i.e. average coefficient of variation of 14% (n = 19). The calculation of the ratio between biomass activity and the amount of viable biomass (phospholipid) at different filter depths indicated a substantial increase of this ratio with filter depth. This indicated an increased biomass activity per unit amount of viable biomass deeper in the biofilters, where biofilm thickness is low. The comparison of the filter profiles of biomass activity and dissolved biodegradable organic matter (BOM), expressed as theoretical oxygen demand, showed a high correlation between these profiles. Consequently, BRP results appear to be good indicators of the BOM removal capacity of the filter biomass. Therefore, BRP results can potentially be used in certain cases instead of BOM measurements for the assessment of the BOM removal capacity of drinking water biofilters, operated under different conditions. This is important because of the relative complexity of the measurements of BOM surrogates, e.g. assimilable organic carbon and biodegradable dissolved organic carbon, and BOM components.     

Development of a new method for the determination of nitrosamines by micellar electrokinetic capillary chromatography

A new method was developed for separation and quantification of nitrosamines by micellar electrokinetic capillary chromatography (MEKC). The effects of composition of the buffer, concentration of sodium dodecyl sulfate (SDS), gamma-cyclodextrin (CD) and pH on the separation and migration times of the nitrosamines were investigated. The different instrumental variables affecting sensitivity and resolution, such as power supply, injection mode and wavelength for measurement, were carefully optimized. The direct application of this method to aqueous synthetic samples allowed the separation and determination of nitrosamine mixtures at the mg x L(-1) level. The calibration curves revealed a linear range between 0.25 and 10 mg x L(-1), with detection limit (DL) varying from 0.16 to 0.27 mg x L(-1), quantification limit (QL) varying from 0.52 to 0.90 mg x L(-1), and RSD relative standard deviation (RSD) from 4.5% to 8.5%. The proposed method was successfully applied to the determination of dimethylnitrosamine (DMN), diethylnitrosamine (DEN), N-nitrosopyrrolidine (NPYR), N-nitrosomorpholine (NMOR) and N-nitrosopiperidine (NPIP).     

回弹法检测混凝土抗压强度实际应用分析

回弹法检测混凝土抗压强度在实际施工中有着广泛的应用。通过在青海马平高速公路施工中利用回弹仪对部分混凝土试块进行强度值对比试验，对回弹法在实际施工过程中的适用性、准确性问题进行了分析，并对回弹法在实际使用过程中应注意的问题进行了阐述。     

A new method for remediation of sandy slopes susceptible to seepage flow using EPS-block geofoam

Using expanded polystyrene (EPS) geofoam (geofoam block) in slope remediation projects has drawn interest from the civil engineering sector for its ease of application and budget saving features. According to design precedence, all slope remediation applications that use geofoam blocks should incorporate permanent drainage systems to prevent instability of the lightweight geofoam blocks due to hydrostatic and seepage pressures. In this study, a new method for slope remediation using geofoam blocks was tested through physical laboratory experiments. For this purpose, a total of 24 lysimeter (dimensions of 60 cm height, 20 cm width, and 200 cm length) experiments (including duplicates) were conducted in which seepage through a geofoam block slope system were generated with three different constant water levels in the water reservoir of the lysimeter. Geofoam blocks (dimensions of 2.5 cm height, 5 cm width, and 15 cm length) were assembled to form embankment type configuration at the toe section of the sandy slopes. This study also included coupled numerical model simulations that were comprised of variably saturated flow modeling and slope stability modeling which could be implemented successfully for the global static failure analysis of the geofoam block slope system comprised of two mediums with different geotechnical characteristics. In addition to global static stability failure analysis, which involved conventional limit equilibrium analysis for the geofoam block slope system, hydrostatic sliding mechanism was investigated which provided insight into using an overburden concept to increase the resistance against horizontal driving forces. Experimental and numerical modeling results showed that the geofoam block slope system was stable even though the phreatic surface was above the bottom of the geofoam block assemblage. For this reason, the embankment type configuration tested in this study can be considered a viable remediation technique where seepage induced deep-seated global stability and hydrostatic sliding failures are a concern.