Boron removal by the duckweed Lemna gibba: a potential method for the remediation of boron-polluted waters

Boron (B) is often found in polluted and desalinated waters. Despite its potentially environmental damaging effects, efficient treatments are lacking. The duckweed Lemna gibba has been shown to remove toxic elements from water; however, its applicability to B removal is unknown. In this study, L. gibba was examined for its tolerance to B in water and its B removal efficiency. Duckweed plants were grown in outdoor 12-day batch experiments in nutrient solution containing 0.3-10 mg B L(-1). Plant biomass production was not affected by B over the tested concentrations during the 12-day cultivation period. Boron removal and the bioconcentration factor of B in L. gibba were highest at initial B concentrations below 2 mg L(-1), and decreased as the initial B concentration increased. Boron content in the plants at the end of the experiment ranged between 930 and 1900 mg kg(-1) dry weight, and was comparable to that of wetland plants reported to be good B accumulators. Boron removal by L. gibba may therefore be a suitable option for the treatment of water containing B concentrations below 2 mg L(-1).     

22-nm Half-pitch extreme ultraviolet node development at the SEMATECH Berkeley microfield exposure tool

Microfield exposure tools continue to play a dominant role in the development of extreme ultraviolet (EUV) resists. Here we present an update on the SEMATECH Berkeley 0.3-NA microfield exposure tool and summarize the latest test results from high-resolution line-space printing. Printing down to 20-nm is presented with large process latitude at 22-nm half-pitch lines. Also presented are line-edge roughness results along with a discussion of the importance of mask contributors to line-edge roughness measured in resist. Finally we briefly describe an upgrade to the tool that will enable EUV resist development at the 16-nm half-pitch node and beyond. (This paper was presented in MNE 2008 conference, <http://www.mne08.org>, <http://www.mne-conf.org>).     

Sparsity-based single-shot subwavelength coherent diffractive imaging

Coherent Diffractive Imaging (CDI) is an algorithmic imaging technique where intricate features are reconstructed from measurements of the freely diffracting intensity pattern. An important goal of such lensless imaging methods is to study the structure of molecules that cannot be crystallized. Ideally, one would want to perform CDI at the highest achievable spatial resolution and in a single-shot measurement such that it could be applied to imaging of ultrafast events. However, the resolution of current CDI techniques is limited by the diffraction limit, hence they cannot resolve features smaller than one half the wavelength of the illuminating light. Here, we present sparsity-based single-shot subwavelength resolution CDI: algorithmic reconstruction of subwavelength features from far-field intensity patterns, at a resolution several times better than the diffraction limit. This work paves the way for subwavelength CDI at ultrafast rates, and it can considerably improve the CDI resolution with X-ray free-electron lasers and high harmonics.     

Surface jumping in a harmonic model of trans-octatetraene: Franck—condon factors and accepting vibrational modes in s1→S0 non-vertical radiationless transition

A phase-space method for finding the accepting modes in a non-vertical radiationless vibronic transition and for recognizing the final state with the largest Franck—Condon factor is applied to a harmonic model of the S₁ → S₀ relaxation in trans-octatetraene. Input required for the analysis includes the energy gap between S₁ and S₀, normal mode frequencies, reduced masses, and eigenvectors (including the Duschinsky rotation matrix), and the molecule equilibrium configurations (bond lengths and angles) in S₁ and S₀. Some of these data are taken from published experimental results and some are calculated in this work. The energy gap of 0.132 au is much larger than the energy of a vertical transition, which is only 0.047 au. The phase-space method gives a closed-form analytic solution for how to divide the excess energy between the accepting modes. The final distribution includes a large excitation of the two CH₂ end groups, where the motion of the two hydrogen atoms within each quasilocal CH₂ group is antisymmetric; a symmetric stretch of the two central C-H bonds of the molecule; and small totally symmetric bending of the whole molecule. Comparison of Franck-Condon factors (exact within the harmonic model) of the final state obtained by the phase-space analysis and of other similar isoenergetic states shows that the phase-space method indeed chooses the most probable final energy distribution. Possible modifications of these results due to anharmonic effects are discussed.     

Use of nonpolar processing aids to improve the efficiencies of extruded polyolefins

The addition of nonpolar processing aids has been shown to widen the processing window for manufacturers of polyolefin film and other extruded products. Opportunities exist to run lines stably at faster speeds with power savings. The benefits of using a nonpolar processing aid in blown film are discussed. J. VINYL ADDIT. TECHNOL., 13:155–158, 2007. © 2007 Society of Plastics Engineers     

Quantitative recovery of high purity nanoporous silica from waste products of the phosphate fertilizer industry

This study reports on the quantitative recovery of high purity nanoporous silica from wastes material (H₂SiF₆) of the phosphate fertilizer industry and Na₂O·SiO₂. The silica recovered from the wastes was compared with silica from the reaction of H₂SO₄ and Na₂O·SiO₂ because H₂SO₄ is commonly used. The product recovered from the wastes material and H₂SO₄ were 99.3% and 99.1% pure, respectively. The quantity recovered were 22.30 g and 20.11 g, respectively. The product had superior properties suitable for applications such as chromatography, reinforcing material for rubber and plastics. The process may significantly reduce the release of SiF₄ gas into the environment.     

Detection of Alternaria fungal contamination in cereal grains by a polymerase chain reaction-based assay

Alternaria sp. are important fungal contaminants of grain products; they secrete four structural classes of compounds that are toxic or carcinogenic to plants and animals and cause considerable economic losses to growers and the food-processing industry. Alternaria toxins have been detected by high-performance liquid chromatography (HPLC), enzyme-linked immunosorbent assay, and other techniques. Here, we report the development of a polymerase chain reaction (PCR)-based method for the detection of Alternaria DNA. PCR primers were designed to anneal to the ITS1 and ITS2 regions of the 5.8S rDNA gene of Alternaria alternata or Alternaria solani but not to other microbial or plant DNA. We compared the sensitivity of PCR in detecting Alternaria DNA, that of the HPLC method in detecting Alternaria alternariol and alternariol methyl ether toxins, and that of the morphological examination of mycelia and conidia in experimentally infested corn samples. The sensitivity of toxin detection for HPLC was above the level of contamination in a set of commercially obtained grain samples, resulting in negative scores for all samples, while the PCR-based method and mold growth plating followed by morphological identification of Alternaria gave parallel, positive results for 8 of 10 samples. The PCR assay required just 8 h, enabling the rapid and simultaneous testing of many samples at a low cost. PCR-based evidence for the presence of Alternaria DNA followed by positive assay results for Alternaria toxins would support the rejection of a shipment of grain.     

The Perception of Correlation in Scatterplots

We present a rigorous way to evaluate the visual perception of correlation in scatterplots, based on classical psychophysical methods originally developed for simple properties such as brightness. Although scatterplots are graphically complex, the quantity they convey is relatively simple. As such, it may be possible to assess the perception of correlation in a similar way. Scatterplots were each of 5.0° extent, containing 100 points with a bivariate normal distribution. Means were 0.5 of the range of the points, and standard deviations 0.2 of this range. Precision was determined via an adaptive algorithm to find the just noticeable differences (jnds) in correlation, i.e., the difference between two side‐by‐side scatterplots that could be discriminated 75% of the time. Accuracy was measured by direct estimation, using reference scatterplots with fixed upper and lower values, with a test scatterplot adjusted so that its correlation appeared to be halfway between these. This process was recursively applied to yield several further estimates. Results of the discrimination tests show jnd(r) = k (1/b – r), where r is the Pearson correlation, and parameters 0 < k, b < 1. Integration yields a subjective estimate of correlation g(r) = ln(1 – br) / ln(1 – b). The values of b found via discrimination closely match those found via direct estimation. As such, it appears that the perception of correlation in a scatterplot is completely described by two related performance curves, specified by two easily‐measured parameters.