EC Methods Research Articles

Electrochemical Fischer-Tropsch chemistry across transition metals: A paradigm shift in sustainable liquid fuel production

This study explores electrochemical Fischer–Tropsch (EC F-T) synthesis as an eco-friendly approach for liquid fuel production, departing from conventional energy-intensive methods. While EC syngas generation is well-explored, the synthesis of F-T chemistry using CO2 and CO feed gases remains relatively unexplored. Investigating various transition metals, including Ti, Zr, V, Mo, Fe, Co, Ni, Pd, Cu, Ag, Au, Zn, and Cd, we present compelling evidence of F-T chemistry, yielding long-chain hydrocarbons (CnH2n and CnH2n+2, n=2–7), with Zn being an exception. This breakthrough involves surface C-C coupling chain growth, resembling traditional F-T synthesis, incorporating *CO and *CHx insertion reactions. Density of states and energy states near the Fermi level were analyzed. The experimental framework enhances our understanding of C-C coupling mechanisms, offering insights into environmentally friendly EC methods for long-chain hydrocarbon production and advancing innovative strategies in sustainable F-T synthesis for future energy solutions.

(Digital Presentation) Porous Silicon Formed by Electrochemical, Chemical and Combined Etching

This work is devoted the thermophysical characteristics (TPC) of PS formed by Electrochemical, Metal-assisted chemical and combined etching methods. The TPC of PS/MACE+EC formed by the MACE+EC– method is higher than those of the PS/EC and PS/MACE samples formed by the EC and MACE methods. The energy activity of water splitting on the surface of PS/MACE+EC is higher than the energy activity of the PS/EC and PS/MACE samples. The combined (MACE+EC) method is the best method for obtaining PS, which has the highest energy activity in water splitting processes. The activation energy of water splitting processes Ea(PS/MACE+EC) is higher than the energy activity of the Ea(PS/EC) and Ea(PS/MACE) samples. The presence of Ni particles in the pores of PS<Ni> stabilizes the them TPC. The TPC of PS were studied in comparison with the TPC of crystalline (c-Si) and powdered silicon (powder-Si). It is known that PS has a high catalytic activity of hydrogen evolution during photoelectrochemical splitting of water. For example, the use of a surface enriched Ni layer on the surface of a PS photocathode PS<Ni> made it possible to increase its catalytic activity two times higher than the catalytic activity of the Pt- electrode in the reaction of hydrogen evolution [1]. The TPC of PS samples formed by EC, MACE and combined (MACE+EC)- etching methods are studied in comparison with the TPC of c-Si and powder-Si samples, Table. Method Electrolyte Composition Marked I Et1 HF:H2O2=1:1 EC II Et2 HF:H2O2: Ni(NO3)2 =1:1:1 МАСЕ III Et3 HF:H2O2: Ni(NO3)2 =1:1:1 EC+МАСЕ According of electron microscopy research the highest porosity is observed on the PS/MACE+EC samples, the smallest - on the PS/MACE sample formed by the MACE- method. The Raman spectra testify this, PS/MACE+EC(Et3) samples have a higher intensity of the Raman peak at a high-frequency shift due to electron-phonon scattering, the intensity and frequency of which depend on the concentration of scattering centers and, consequently, on the conditions for the formation of pores [2]. The TPC of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) spectra record changes in the mass Δm of the sample and heat flux ΔQ with an isobaric temperature change ΔT at the points of T-characteristic. An analysis of the calorimetric TPC and the TGA and DSC spectra shows that c-Si and powder have almost the same patterns of change in thermal conductivity, in contrast to the PS-spectra. The PS/EC, PS/MACE samples have the maximum change in heat flux Q(PS/EC)=187.6 mW, Q(PS/MACE)=231.6 mW, in contrast to powder-Si Q(powder-Si)=107.1 mW and c-Si ΔQ(c-Si)=65.02 mW. This dependence, which is responsible for the heat flux ΔQ change in the high T-range is associated with the maximum developed surface PS. Due to the fact that the presence of the Ni in the pores of PS<Ni>/MACE and PS<Ni>/MACE+EC stabilizes the TPC of PS, and thereby prevents significant changes in the TPC of Ni-containing PS<Ni>, in contrast to PS that does not Ni-contain in pores. Also have carried out experiments on the evaporation of water droplets at room temperature from the surface of c-Si and PS/EC, PS/MACE PS/MACE+EC samples. Experiments on the evaporation of water droplets at Troom from the surface of crystalline and PS samples obtained by various etching methods showed that the highest energy activity is observed in PS/MACE+EC samples, Ea(PS/MACE+EC) = 0.2087 eV, which is much higher than Ea(PS/EC) = 0.070 eV, Ea(PS/MACE) = 0.050 eV and Еа(c-Si) = 0.025 eV,The porous surface of the PS/MACE+EC sample has the highest energy activity compared to the PS/EC and PS/MACE samples, which is due to the high porosity of PS/MACE+EC. The PS/MACE and PS/MACE+EC samples showed high energy stability over 1 year in water evaporation experiments. The values of the heat capacities of various EC-, MACE-, EC+MACE - etching methods are established: - Cp(c -Si) = 20.7 KJ/gK, Cp(powder-Si) = 13.11 KJ/gK, Cp(PS/MACE) = 12.79 KJ/gK, Cp(PS/AE) = 5.62 KJ/gK.Combination of electrochemical etching with Ni-stimulated and chemical etching (EC+MACE) makes the possibility Ni-containing nanoporous silicon with high energy activity in water splitting processes: - Еа(PS/MACE+EC) = 0.2087 eV, Еа(PS/MACE) = 0.070 eV , Еа(PS/АЕ) =0.050 eV.The Ni- presence in the pores stabilizes the TPC of PS/MACE and PS/MACE+EC. The stability of Ni-containing samples PS/MACE+EC) and Ea(PS/MACE) is maintained for one year. [1] K.B. Tynyshtykbayev et al. Russian Microelectronics, 2016, Vol. 45, Nos. 8–9, pp. 603–612. https://doi.org/10.1134/S106373971608014X[2] K. Tynyshtykbayev et al. ECS Journal of Solid State Science and Technology, 2021 10 013009 DOI: 10.1149/2162-8777/abdd86

A dual-mode "signal-on" split-type aptasensor for bisphenol A via target-induced hybridization chain reaction amplification.

Herein, a dual-mode detection system was constructed for efficient and accurate detection of bisphenol A (BPA) with the assistance of the BPA-induced hybridization chain reaction (HCR). The captured DNA (cDNA) was first modified on the surface of magnetic spheres modified with gold nanoparticles and polydopamine and then hybridized with the BPA aptamer to form double-stranded DNA (dsDNA). In the presence of the BPA target, the BPA aptamer was released from the surface of the magnetic sphere. The free cDNA triggered a HCR to construct a DNA duplex. Methylene blue (MB), as a bifunctional probe, was intercalated into the double-stranded DNA to amplify the photocurrent (IPEC) of the CdS-modified electrode and generate an electrochemical current (IEC) at the same time. Under the optimized conditions, the PEC and EC signal responses of the system were linear to the logarithm of BPA concentration in the range of 1.0 × 10-10 M to 1.0 × 10-5 M. The detection limits were found to be 1.27 × 10-11 M and 3.0 × 10-11 M using the PEC and EC methods, respectively. The constructed dual-mode biosensor exhibited good performance for real sample analysis, demonstrating its promising potential for practical applications. In addition, this dual-mode detection strategy provides more accurate and reliable detection results.

A novel method for estimating carbon emission based on industrial metabolism: Blast furnace iron-making with micro mechanism model

The carbon emission accounting method provided by IPCC depends heavily on the emission coefficients of various types of fossil fuels. Literature reviews present the emission coefficients are usually assigned widely in various industrial systems, due to the absence of considerations on the mechanism and process of carbon emissions. It seems more suitable for estimating the massive carbon emissions at a macro level of a region or country, with tolerable estimating errors. For more accurate carbon accounting and prediction, it is crucial to develop a novel methodology on a micro mechanism model that is independent of the historical data and emission coefficients for a given industrial system at a micro level. Via analysing the mass energy balances and simulating the industrial metabolic pathways, instead of using the emission coefficients, a micro mechanism model of blast-furnace iron-making system is established based on the network of industrial metabolism, for offering an alternative carbon accounting methodology. In the case study, a network of industrial metabolism is established on the fundamental chemical reactions that is conducted in the blast-furnaces and the iron-making system. The metabolic simulation shows the dynamic change curves of metabolic variables at each moment. As a result, the carbon emission intensities estimated by IPCC, WSA, JM, WRI, EC, and IM methods are respectively 831.61 kg, 1500.00 kg, 1171.6 kg, 1381.64 kg, 792.45 kg, and 647.82 kg per ton of molten iron. The bias in the carbon accounting primarily results from the differences of boundary conditions. Generally, the novel carbon accounting methodology based on the industrial metabolism better indicates the carbon emissions at a micro level for the iron-making systems under China’s industrial conditions.

Comparison Study on Sonodirect and Sonoalternate Current Electrocoagulation Process for Domestic Wastewater Treatment.

Nowadays, there is a problem related to wastewater handling which is released from different activities. The electrocoagulation method has been a dominant treatment method for wastewater treatment. There are different forms of electrocoagulation methods for wastewater treatment. Nevertheless, there was no comparison made for the removal efficiency of the sonoalternate current (SAC), alternate current (AC), sonodirect current (SDC), and direct current (DC) electrocoagulation process. The efficiency of electrocoagulation methods was compared for their removal of chemical oxygen demand (COD) from Jimma University domestic wastewater. Batch Reactor DC/AC electrocoagulation cell was used to determine the removal efficiency. During the comparison, the response surface methodology (RSM) was used to analyze and optimize the data taken from the laboratory. Besides, ANOVA was used to analyze the interaction effects of different parameters. The removal of COD from domestic wastewater was achieved with DCE, ACE, SDCE, and SACE which were 82.6%, 86.58%, 88.6%, and 92.5%, respectively, under optimal experimental conditions. From the finding, SACE was more successful at removing % COD than the DCE, ACE, and SDCE methods. For DCE and SDCE, the formation of an impermeable oxide layer at the cathode and the occurrence of corrosion at the anode due to oxidation made the COD removal process less efficient compared with SACE processes. From the experimental results it can be concluded that the SACE has the lowest power consumption and higher process efficiency than the other EC methods and can be a promising solution for removing pollutants from domestic wastewater.

Measurement report: Characterization of uncertainties in fluxes and fuel sulfur content from ship emissions in the Baltic Sea

Abstract. Fluxes of gaseous compounds and nanoparticles were studied using micrometeorological methods at Harmaja in the Baltic Sea. The measurement site was situated beside the ship route to and from the city of Helsinki. The gradient (GR) method was used to measure fluxes of SO2, NO, NO2, O3, CO2, and Ntot (the number concentration of nanoparticles). In addition, the flux of CO2 was also measured using the eddy-covariance (EC) method. Distortion of the flow field caused by obstacles around the measurement mast was studied by applying a computation fluid dynamic (CFD) model. This was used to establish the corresponding heights in the undisturbed stream. The wind speed and the turbulent parameters at each of the established heights were then recalculated for the gradient model. The effect of waves on the boundary layer was taken into consideration, as the Monin–Obukhov theory used to calculate the fluxes is not valid in the presence of swell. Uncertainty budgets for the measurement systems were constructed to judge the reliability of the results. No clear fluxes across the air–sea nor the sea–air interface were observed for SO2, NO, NO2, NOx (= NO + NO2), O3, or CO2 using the GR method. A negative flux was observed for Ntot, with a median value of -0.23×109 m−2 s−1 and an uncertainty range of 31 %–41 %. For CO2, while both positive and negative fluxes were observed, the median value was −0.081 µmol m−2 s−1 with an uncertainty range of 30 %–60 % for the EC methods. Ship emissions were responsible for the deposition of Ntot, while they had a minor effect on CO2 deposition. The fuel sulfur content (FSC) of the marine fuel used in ships passing the site was determined from the observed ratio of the SO2 and CO2 concentrations. A typical value of 0.40±0.06 % was obtained for the FSC, which is in compliance with the contemporary FSC limit value of 1 % in the Baltic Sea area at the time of measurements. The method to estimate the uncertainty in the FSC was found to be accurate enough for use with the latest regulations, 0.1 % (Baltic Sea area) and 0.5 % (global oceans).

Accurate measurement of wind drift and evaporation losses could improve water application efficiency of sprinkler irrigation systems − A comparison of measuring techniques

Wind drift and evaporation losses (WDEL) are some of the major sprinkler-irrigation losses which exist even in a well-managed irrigation system. Several research studies found a wide range of WDEL under different and nearly similar configurations of sprinkler irrigation systems under similar weather conditions but using different methodologies to measure the WDEL. The specific objective of this research was to evaluate the three most commonly used measuring techniques (standard catch-can tests (CC), an electrical conductivity method (EC), and a physical-based mathematical approach (PM)) for WDEL on a common sprinkler irrigation system under the same climatic conditions. We conducted 33 experiments from May to September of 2018 near Prosser, Washington. Twenty-two of these experiments were during the daylight hours, and 11 were during the night. We used catch-cans of 29.3 cm diameter and rain gauges (diameter of 10 cm) to collect water to measure the irrigation water's electrical conductivity. Mass and heat transfer approaches were used in the PM technique. The results showed that the three techniques yielded statistically different mean WDEL. The highest WDELs were in CC (22.8%), followed by EC (17.5%) and PM (6.8%) techniques. The CC WDELs were better correlated with PM than the EC approach. The mean nighttime WDEL for the EC and CC methods were not statistically different (p > 0.05). The CC WDELs were more closely related to wind speed than the vapor pressure deficit. The EC and PM approaches have a higher correlation to the vapor pressure deficit. The overall conclusion disclosed that the more we use indirect measurement methods, the more the chances of erroneous numbers. The EC and PM approaches are likely limited to measuring droplet evaporation as the latter includes several assumptions. The CC approach is a direct measurement of the WDEL.

Exploring young women\u2019s reasons for adopting intrauterine or oral emergency contraception in the United States: a qualitative study

BackgroundThe recent focus on increasing access to long-acting reversible contraceptive methods has often overlooked the diverse reasons why women may choose less effective methods even when significant access barriers have been removed. While the copper intrauterine device (IUD) is considered an acceptable alternative to emergency contraception pills (ECPs), it is unclear to what extent low rates of provision and use are due to patient preferences versus structural access barriers. This study explores factors that influence patients’ choice between ECPs and the copper IUD as EC, including prior experiences with contraception and attitudes toward EC methods, in settings where both options are available at no cost.MethodsWe telephone-interviewed 17 patients seeking EC from three San Francisco Bay Area youth-serving clinics that offered the IUD as EC and ECPs as standard practice, regarding their experiences choosing an EC method. We thematically coded all interview transcripts, then summarized the themes related to reasons for choosing ECPs or the IUD as EC.ResultsTen participants left their EC visit with ECPs and seven with the IUD as EC option. Women chose ECPs because they were familiar and easily accessible. Reasons for not adopting the copper IUD included having had prior negative experiences with the IUD, concerns about its side effects and the placement procedure, and lack of awareness about the copper IUD. Women who chose the IUD as EC did so primarily because of its long-term efficacy, invisibility, lack of hormones, longer window of post-coital utility, and a desire to not rely on ECPs. Women who chose the IUD as EC had not had prior negative experiences with the IUD, had already been interested in the IUD, and were ready and able to have it placed that day.ConclusionsThis study highlights that women have varied and well-considered reasons for choosing each EC method. Both ECPs and the copper IUD are important and acceptable EC options, each with their own features offering benefits to patients. Efforts to destigmatize repeated use of ECPs and validate women’s choice of either EC method are needed to support women in their EC method decision-making.

On the Possibilities and Considerations of Interfacing Ultra-High Vacuum Equipment with an Electrochemical Setup.

Efficient electrocatalysts are required in order for electrocatalysis to play a large role in a future largely based on renewable energy sources. To rationally design these catalysts we need to understand the fundamental origin of their activities. In order to elucidate the relationship between catalyst structure and electrochemical behaviour, we investigate well-defined single-crystal catalysts in a UHV chamber interfaced with an electrochemical setup. Using the capabilities of UHV based methods, we can prepare more complex surface structures than it is possible with traditional EC methods and investigate their electrochemical behaviour. We exemplify this by showing results from both clean and intentionally structured Pt(111), Cu(111) and Pt/Cu(111).

Marginalized Multiview Ensemble Clustering.

Multiview clustering (MVC), which aims to explore the underlying cluster structure shared by multiview data, has drawn more research efforts in recent years. To exploit the complementary information among multiple views, existing methods mainly learn a common latent subspace or develop a certain loss across different views, while ignoring the higher level information such as basic partitions (BPs) generated by the single-view clustering algorithm. In light of this, we propose a novel marginalized multiview ensemble clustering (M2VEC) method in this paper. Specifically, we solve MVC in an EC way, which generates BPs for each view individually and seeks for a consensus one. By this means, we naturally leverage the complementary information of multiview data upon the same partition space. In order to boost the robustness of our approach, the marginalized denoising process is adopted to mimic the data corruptions and noises, which provides robust partition-level representations for each view by training a single-layer autoencoder. A low-rank and sparse decomposition is seamlessly incorporated into the denoising process to explicitly capture the consistency information and meanwhile compensate the distinctness between heterogeneous features. Spectral consensus graph partitioning is also involved by our model to make M2VEC as a unified optimization framework. Moreover, a multilayer M2VEC is eventually delivered in a stacked fashion to encapsulate nonlinearity into partition-level representations for handling complex data. Experimental results on eight real-world data sets show the efficacy of our approach compared with several state-of-the-art multiview and EC methods. We also showcase our method performs well with partial multiview data.

A Comparison between Different Methods of Estimating Anaerobic Energy Production.

Purpose: The present study aimed to compare four methods of estimating anaerobic energy production during supramaximal exercise.Methods: Twenty-one junior cross-country skiers competing at a national and/or international level were tested on a treadmill during uphill (7°) diagonal-stride (DS) roller-skiing. After a 4-minute warm-up, a 4 × 4-min continuous submaximal protocol was performed followed by a 600-m time trial (TT). For the maximal accumulated O2 deficit (MAOD) method the O2-speed regression relationship was used to estimate the O2 demand during the TT, either including (4+Y, method 1) or excluding (4-Y, method 2) a fixed Y-intercept for baseline O2. The gross efficiency (GE) method (method 3) involved calculating metabolic rate during the TT by dividing power output by submaximal GE, which was then converted to a O2 demand. An alternative method based on submaximal energy cost (EC, method 4) was also used to estimate O2 demand during the TT.Results: The GE/EC remained constant across the submaximal stages and the supramaximal TT was performed in 185 ± 24 s. The GE and EC methods produced identical O2 demands and O2 deficits. The O2 demand was ~3% lower for the 4+Y method compared with the 4-Y and GE/EC methods, with corresponding O2 deficits of 56 ± 10, 62 ± 10, and 63 ± 10 mL·kg−1, respectively (P < 0.05 for 4+Y vs. 4-Y and GE/EC). The mean differences between the estimated O2 deficits were −6 ± 5 mL·kg−1 (4+Y vs. 4-Y, P < 0.05), −7 ± 1 mL·kg−1 (4+Y vs. GE/EC, P < 0.05) and −1 ± 5 mL·kg−1 (4-Y vs. GE/EC), with respective typical errors of 5.3, 1.9, and 6.0%. The mean difference between the O2 deficit estimated with GE/EC based on the average of four submaximal stages compared with the last stage was 1 ± 2 mL·kg−1, with a typical error of 3.2%.Conclusions: These findings demonstrate a disagreement in the O2 deficits estimated using current methods. In addition, the findings suggest that a valid estimate of the O2 deficit may be possible using data from only one submaximal stage in combination with the GE/EC method.

Influence of softening sequencing on electrocoagulation treatment of produced water

Electrocoagulation has been used to remove solids and some metals from both water and wastewater sources for decades. Additionally, chemical softening is commonly employed in water treatment systems to remove hardness. This paper assesses the combination and sequence of softening and EC methods to treat hydraulic fracturing flowback and produced water from shale oil and gas operations. EC is one of the available technologies to treat produced water for reuse in frac fluids, eliminating not only the need to transport more water but also the costs of providing fresh water. In this paper, the influence of chemical softening on EC was studied. In the softening process, pH was raised to 9.5 and 10.2 before and after EC, respectively. Softening, when practiced before EC was more effective for removing turbidity with samples from wells older than one month (99% versus 88%). However, neither method was successful in treating samples collected from early flowback (1-day and 2-day samples), likely due to the high concentration of organic matter. For total organic carbon, hardness, Ba, Sr, and B removal, application of softening before EC appeared to be the most efficient approach, likely due to the formation of solids before the coagulation process.

Knowledge, attitude and practice of emergency contraception among health care providers in Ismailia, Egypt

Abstract Objective To explore the knowledge, attitude and practice of health care providers in Ismailia, Egypt regarding emergency contraception. Participants and method A structured questionnaire was distributed to a total of 270 health care providers (obstetrics and gynecology specialists and general practitioners or family physicians). The questionnaire contained four main domains: demographic characteristics; knowledge about EC; attitude toward EC; and practice of EC. Results Knowledge of specialists was significantly higher than general practitioners/family physicians regarding the three most commonly used methods of EC, viz; combined oral contraceptive (Yuzpe) method, progesterone only pills (plan B) method and IUCD. Only 39.5% of specialists and 24.0% of GPs/family physicians had good knowledge of EC ( p = 0.01). 45.7% of specialists and 42.6% of GPs/family physicians had favorable attitude toward EC with no significant difference. 39.5% of specialists and 26.6% of GPs/family physicians reported ever prescribing EC. Yuzpe method was the most commonly prescribed method by specialists (31.5%) and GPs/family physicians (27.0%) with no significant difference. Knowledge and favorable attitude were significantly associated in both groups. Age and years of experience significantly affected the three outcome measures. Conclusion A deficit in knowledge and a negative attitude shown by health care providers lead to an insufficient use of EC methods.

Quantitative bioactivity prediction and pharmacophore identification for benzotriazine derivatives using the electron conformational–genetic algorithm in QSAR

The electron conformational–genetic algorithm (EC–GA), a sophisticated hybrid approach combining the GA and EC methods, has been employed for a 4D–QSAR procedure to identify the pharmacophore for benzotriazines as sarcoma inhibitors and for quantitative prediction of activity. The calculated geometry and electronic structure parameters of every atom and bond of each molecule are arranged in a matrix described as the electron–conformational matrix of contiguity (ECMC). By comparing the ECMC of one of the most active compounds with other ECMCs we were able to obtain the features of the pharmacophore responsible for the activity, as submatrices of the template known as electron conformational submatrices of activity. The GA was used to select the most important descriptors and to predict the theoretical activity of training and test sets. The predictivity of the model was internally validated. The best QSAR model was selected, having r 2 = 0.9008, standard error = 0.0510 and cross-validated squared correlation coefficient, q 2 = 0.8192.

Evaluation of Petrifilm™ EC method for enumeration ofE. colifrom soil

To evaluate the suitability of commercially available Petrifilm EC plates for enumeration of Escherichia coli from soil. A confirmed E. coli strain isolated from liquid swine manure was inoculated into sterilized sandy clay loam and loam soils at the concentrations of 10(2), 10(3), 10(5) CFU g(-1) of soil. The efficiency of recovery on Petrifilm EC plates for soils spiked with E. coli was compared with standard membrane filtration techniques on m-FC basal medium supplemented with 3-bromo-4-chloro-5-indoyl-beta-D-glucopyranoside (BCIG) and most probable numbers (MPN) techniques in E. coli medium with 4-methylumbelliferyl-beta-D-glucuronide (EC-MUG) broth. Petrifilm EC and m-FC (BCIG) methods were then assessed for the ability to recover E. coli from field soils applied with swine manure. No significant differences (P > 0.05) were observed between Petrifilm EC, m-FC (BCIG) and MPN methods for the recovery of E. coli from spiked samples, irrespective of soil type. However, recovery of E. coli from manure-applied field soil samples showed a significant difference (P < 0.05) between the Petrifilm EC method and the m-FC method in enumerating E. coli possibly as a result of false positives on m-FC. The Petrifilm EC method is suitable for the enumeration of E. coli from soil with a detection limit of 10 CFU g(-1) soil. The commercially available Petrifilm EC method is comparatively low cost, easy to use method for the enumeration of E. coli from soil without the need for further confirmation tests.

A comparison between latent heat fluxes over grass using a weighing lysimeter and surface renewal analysis

An experiment to study the performance of the hourly sensible ( H ) and latent heat ( LE ) estimates over grass using surface renewal, SR , analysis was carried out at the University of California West Side Field Station near Five Points (San Joaquin Valley, CA). Hourly eddy covariance, EC , and SR sensible heat fluxes were averaged from their respective half-hourly fluxes. They were used to estimate hourly latent heat flux, LE , by calculating the residual of the energy balance equation, i.e., LE EC = R n − G − H EC and LE SR = R n − G − H SR , where R n is the net radiation; G is the soil heat flux; H is the buoyant sensible heat flux and the H subscripts denote measurements values from the EC and SR methods. Regardless of the weather conditions and time of day, H SR was comparable to H EC ; especially from sunrise until the afternoon formation of a capping inversion due to regional advection of sensible heat flux. The main source of energy contributing to LE was ( R n − G ). When ( R n − G ) was positive, on average, H contributed to 9% of ( R n − G ) when data were collected under unstable conditions, but it accounted for 21% under stable conditions . In general, correlation between measured LE using a weighing lysimeter, LE Lys , and LE SR was R 2 = 0.97 which was substantially higher than between LE Lys and ( R n − G ), R 2 = 0.93. In principle, the observed performance can be extrapolated to all irrigated, short, and dense-canopy vegetation that is mostly decoupled from the environment. Because for these surfaces the zero-plane displacement and the aerodynamic surface roughness length can be estimated as a portion (about 0.7 and 0.12, respectively) of the canopy height, using a two dimensional sonic anemometer capable to record high-frequency sonic temperature provides all the input to determine H SR which in conjunction with ( R n − G ) is required to estimate LE .

Design and fabrication of a miniaturized electrochemical instrument and its preliminary evaluation

A simple microprocessor controlled mini-electrochemical (EC) instrument integrating with square wave voltammetry (SWV) was designed and fabricated. Direct digital frequency synthesizer (DDFS) was exploited in the circuit design to generate a linear and very low frequency scanning waveform for SWV. An ultra-low bias current, a high performance operational amplifier, a lock-in amplifier, and several noise reduction methods, such as cable selection, PCB cleaning, and guarding, were utilized to achieve the capability of ultra-low current measurement. The initial performance test of this SWV-based EC device was also conducted in different ferricyanide solutions. Compared with commercial electrochemical analyzers, the miniaturized EC instrument presented here has the characteristics of low-cost, small size, ease of use and reduced energy consumption. Due to its flexible design, this SWV-based instrument can easily be extended to meet the requirements of the portable and reliable EC chip device integrating other commonly used EC methods.

Adaptive variation in fall cold hardiness of aspen from northwestern Ontario

We investigated adaptive variation in fall cold hardiness development based on the electrical conductivity of tissue diffusates (EC) among 20 aspen provenances from northwestern Ontario. Provenance accounted for over 40% of the total variation in cold injury for seven dates from September through November in three provenance trials. Principal component analysis was performed to summarize the combinations of results for all sampling sites, dates and temperatures (traits). Principal component (PC)-1 represented fully developed cold hardiness differences among provenances; PC-2 represented differences in the timing of the onset of cold hardiness development; and PC-3 represented a site-related difference in cold hardiness development. Heat sum in early summer and late summer precipitation together were the best predictors of absolute degree of cold hardiness (PC-1), whereas temperatures for mid- to late summer were best for predicting onset of cold hardiness development (PC-2). In a second study, we assessed the efficacy of chlorophyll fluorescence (CF) as a simpler technique for determining the cold hardiness of aspen stem samples. Fall cold hardiness of stem samples of 12 of the original 20 provenances was estimated by CF, and the results were evaluated by a visual scoring (VS) method. Correlations between EC and CF measurements from the two studies were moderately strong based on the extent of cold hardiness in October of each year, but were negative for September dates because of a later onset of cold hardiness in the EC study year. Although the EC and CF methods gave similar cold hardiness values for stem samples from 12 provenances, the CF method may be preferred to the EC or VS method for species with chlorophyllous stems because of its greater ease of use.

Evaluation of the lactose Tergitol-7, m-Endo LES, Colilert 18, Readycult Coliforms 100, Water-Check-100, 3M Petrifilm EC and DryCult Coliform test methods for detection of total coliforms and Escherichia coli in water samples

In this study we compared the reference membrane filtration (MF) lactose Tergitol-7 (LTTC) method ISO 9308-1:2000 with the MF m-Endo LES method SFS 3016:2001, the defined substrate chromogenic/fluorogenic Colilert 18, Readycult Coliforms and Water Check methods, and ready-made culture media, 3M Petrifilm EC and DryCult Coli methods for the detection of coliforms and Escherichia coli in various water samples. When the results of E. coli detection were compared between test methods, the highest agreement (both tests negative or positive) with the LTTC method was calculated for the m-Endo LES method (83.6%), followed by Colilert 18 (82.7%), Water-Check (81.8%) and Readycult (78.4%), whereas Petrifilm EC (70.6%) and DryCult Coli (68.9%) showed the weakest agreement. The m-Endo LES method was the only method showing no statistical difference in E. coli counts compared with the LTTC method, whereas the Colilert 18 and Readycult methods gave significantly higher counts for E. coli than the LTTC method. In general, those tests based on the analysis of a 1-ml sample (Petrifilm EC and DryCult Coli) showed weak sensitivity (39.5–52.5%) but high specificity (90.9–78.8%).

167THE USE OF BULL ROUND SPERMATIDS FOR PRODUCING RECONSTRUCTED EMBRYOS

Recently, sperm has been used as a vector to carry exogenous genes for the production of transgenic animals. However, the success in cattle is low, due to deficiencies in oocyte activation and sperm decondensation caused by high disulphide bond (S=S) content in mature sperm. This study was carried out to develop an effective method for producing transgenic animals with round spermatids (RS). Two methods of embryo production—electric fusion (EC) or intracytoplasmic injection (IC)—and three activation treatments were compared. RS were isolated from bull testes by Percoll density gradients (20, 35, 40, 45 and 90%). Fusion between ooplast and RS was performed with a single DC electric pulse delivered by BTX 200 (1.0KVcm−1, 45μs) in 0.28M mannitol solution supplemented with 100μM CaCl2 and 100μMMgCl2. MII oocytes were divided into three activation groups for EC and IC methods, respectively. In Group 1, oocytes were activated with ionomycin (5μM, 5min) prior to EC/IC. In Group 2, oocytes were activated with ionomycin (5μM, 5min) after EC/IC. In Group 3, oocytes were activated twice with ionomycin, before and after EC/IC. All eggs were then incubated in cycloheximide (10μgmL−1) for 5h and cultured in CR1aa medium to Day 8. The rates of cleavage and blastocyst development were evaluated on Days 2 and 8, respectively. All experiments were performed as 5 replicates, and statistical differences were analyzed with one-way ANOVA (P&amp;lt;0.05). In IC, cleavage rates were significantly higher (P&amp;lt;0.05) in Group 3 (99/123, 80.5%) compared to Groups 1 and 2 (31/68, 45.6% and 45/70, 64.3%, respectively). Blastocyst development rates were also significantly higher (P&amp;lt;0.05) in Group 3 (15/123, 12.2%) compared to Group 2 (1/70, 1.4%), but did not differ compared to Group 1 (4/68, 5.9%). In EC, the cleavage rates in all three activation treatment groups remained low (43–45%), and no blastocysts developed. These results suggest that intracytoplasmic RS injection combined with repeated ionomycin activation is more efficient than electric fusion for producing developmentally competent embryos. [Supported by High Technology Development Project for Agriculture and Forestry Korea, MAF-SGRP, 300012-05-3-SB010 and Cho-a Pharm. Co. LTD.]