Evidence for internalization of Escherichia coli into the aerial parts of maize via the root system

Escherichia coli introduced into the hydroponic growing medium of maize plants was detected 48 h later in the shoot. Decapitation of root tips or severing of the plant root system at the root-shoot junction enhanced bacterial internalization. The density of the bacteria in shoots of plants with damaged roots or removed root systems was 27.8 and 23.9 times higher than that in plants with intact roots, respectively. The concentration of viable cells in the hydroponic solution decreased over time from 9.3 x 10(6) CFU/ml at the time of inoculation to 8.5 x 10(1) CFU/ml 4 days thereafter. The number of E. coli cells associated with the roots also decreased with time, but a significant decline appeared only at 4 days postinoculation. At the time of sampling for E. coli presence in the shoot, 10(2) CFU/ml was present in the nutrient solution and 8 x 10(3) CFU/g was associated with the roots. The present study is the first to demonstrate internalization of E. coli via the root in a monocotyledonous plant.     

Outdoor attractancy of males ofMatsucoccus josephi (Homoptera: Matsucoccidae) andElatophilus hebraicus (Hemiptera: Anthocoridae) to synthetic female sex pheromone ofMatsucoccus josephi

The active component of the sex pheromone ofMatsucoccus josephi is (2E,6E,8E)-5,7-dimethyl-2,6,8-decatrien-4-one; the chemical is also a powerful kairomone of adult males and females of the bugElatophilus hebraicus the principal predator ofM. josephi. The presence of theZ isomer (2E,6Z,8E)-5,7-dimethyl-2,6,8-decatrien-4-one does not interfere with the attractancy of the activeE component forM. josephi males or the bug. Our results show a clear dose-response between trap catch ofM. josephi males andE. hebraicus. Conversely, increasing amounts of theZ isomer in the mixture did not affect the attraction of the scale insect males or the bug. The catch ofM. josephi males did not differ significantly among traps of different color, and was significantly higher with traps attached to the tree trunk than those suspended between trees. Comparison of the catch ofM. josephi among the three forests and between pine species suggests that the level of infestation ofPinus halepepsis andPinus brutia ssp.brutia is similar, despite the fact that the latter pine is resistant to the scale insect. Both sexes ofE. hebraicus were trapped in much lower numbers at the more infested sites. This may be related to interference with the activity ofE. hebraicus due to deterioration and drying of parts of the tree crowns and heavy colonization by generalist predators in injured trees.     

High‐resolution measurements of water permeability and solubility in microelectronic‐casing made of a hydrophobic polymeric composite

Exposing the composite polymeric casing of integrated circuits (ICs) to water results in miniscule water absorption, followed by its permeation throughout the packaging, and component damage. Studying water penetration and solubility mechanisms in the IC casing is crucial for understanding water‐related damage mechanisms and protection against them. The main analytical challenge, hereafter, stems from the need to study miniscule water amounts (<0.5 wt %) capable of penetrating the casing, despite its hydrophobic nature. In this article, a TGA has been employed to study the water uptake kinetics in the casing, and to decipher the related water penetration mechanisms. High‐resolution measurements of water adsorption and desorption profiles were performed, followed by calculations of the related activation energies and solubility enthalpies. These data were correlated with a relatively new model that assigned the primary locales of the adsorbed water to the compatible filler–polymer interface. Thus, water permeability is related to molecules hopping between these sites. Finally, we have shown that for the IC casing in our study, the activation energy of water permeation is related to the binding energy of H₂O onto the Si? O? Si groups at the fused‐silica‐filler surface, where they desorb, hop, and reabsorb. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4523–4527, 2006     

Surface-Enhanced Raman Scattering (SERS) of Microorganisms

Normal Raman (NR) spectra and surface-enhanced Raman scattering (SERS) spectra were obtained for the bacterium Escherichia coli and were compared with those of two other microorganisms, Haloferax volcanii and Thiobacillus neapolitanus. It was found that at 514 nm the SERS of E. coli was similar to that of flavin adenine dinucleotide (FAD). Upon increasing the excitation wavelength, contributions from other cell components became evident, and they were attributed to nicotinamide adenine dinucleotide (NAD) or other adenine-containing molecules in the bacterium. A comprehensive study of FAD, riboflavin (RF), NAD, and adenine under various experimental conditions was thus performed to shed light on the features in the SERS obtained for E. coli. Comparison of NR and SERS measurements of the various samples enabled a better understanding of the SERS spectra and their sensitivity to the specific experimental conditions (excess metal ion concentration and laser excitation wavelengths and intensity). It was concluded that SERS is a highly sensitive technique and that careful examination of the spectra can provide important chemical information.     

大地电磁测深的拟地震解释法

在水平层状介质条件下,如果把地层划分为电磁波或弹性波在其中的双程旅行时都相等的“微层”,则大地电磁场和弹性波的位移场的反射函数无论是在表现形式上,或是在物理意义上都是十分相似的。这样的话,大地电磁测深法也可以象地震反射法一样画出“时间剖面”进行地质解释。这种方法还可推广到二维大地电磁测深和电测深资料的解释。通过对二层、三层和四层断面的理论模型试算,说明此方法是可行的。但是,无论是在理论上,还是在实践中都有许多值得研究的问题,例如在MT中反射函数的精度受观测精度及计算方法的影响。因此,研究新的观测方法和计算方法就显得很有必要。再如怎样把地震资料处理中一些消除干扰和提高分辨率的措施用于MT法。     

The effects of immediate stimulus repetition on reaction time and event-related potentials in tasks of different complexity.

Examined the effect of immediate stimulus repetition in lexical decision, face recognition, letter search, face/nonface discrimination, and word/number discrimination tasks using reaction time (RT), accuracy, and event-related brain potential (ERP) measures. Repetition facilitated performance in all tasks and for all stimulus types. However, ERPs were strongly affected by repetition only in lexical decision, face recognition, and letter search, when relatively long stimulus analysis and decision making processes were required. The ERP repetition effect consisted of a significant increase in P300 amplitude and a shortening of its latency. Repetition also resulted in the attenuation of a negative component that was tentatively identified as N400. These results suggest that immediate repetition facilitates stimulus identification and eliminates the need for stimulus analysis processes including access to semantic memory while making categorical decisions. While both factors affected RT, ERPs were modulated primarily by the elimination of the need to access to semantic memory and by the consequent speeding of categorical decision processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Generating function approach for creation of coherent multimode beams by diffractive optics

Tailored compositions of transverse modes provided by mathematical generating functions are exploited for the synthesis of multimode laser beams in free space. We show that analytical equations which are available for the generating functions provide physical insight into modal phase and power balance in multimode coherent light beams. Multimode coherent beams were created by methods of diffractive optics implementing the generating functions. Experimental and computer simulated results demonstrate a good match.     

FTIR Microscopic Studies on Normal, Polyp, and Malignant Human Colonic Tissues

Fourier-Transform Infrared Spectroscopy (FTIR) employs a unique approach tooptical diagnosis of tissue pathology based on the characteristic molecularvibrational spectra of the tissue. The biomolecular changes in the cellularand sub-cellular levels developing in abnormal tissue, including a majorityof cancer forms, manifest themselves in different optical signatures, whichcan be detected in infrared microspectroscopy. This report has two parts. Inthe first part, we report studies on normal, premalignant (polyp) andmalignant human colonic tissues from three patients with different stages ofmalignancy. Our method is based on microscopic infrared study (FTIR-microscopy)of thin tissue specimens and a direct comparison with traditional histopathologicalanalysis, which serves as a gold reference. The limited dataavailable showed normal colonic tissue has a stronger absorption thanpolypoid tumor and cancerous types over a wide region in a total of 100measurements. Detailed analysis showed that there is a significant decreasein total carbohydrate, phosphate and possibly creatine contents for polyp andcancerous tissue types in comparison to the controls. The same trend is maintainedin seven other patients studied. The second part consists of an analysis showingthe influence of various independent factors such as age, sex and grade of malignancy. Ourpreliminary results suggest that among the above three factors, age and gradeof malignancy have significant effect on the metabolites level, but sex has onlyminor effect on the measured spectra. Initial results on Linear DiscriminantAnalysis (LDA) showed good classification between normal and malignant cellsof human colonic tissues.     

Efficiency of phenol biodegradation by planktonic Pseudomonas pseudoalcaligenes (a constructed wetland isolate) vs. root and gravel biofilm

In the last two decades, constructed wetland systems gained increasing interest in wastewater treatment and as such have been intensively studied around the world. While most of the studies showed excellent removal of various pollutants, the exact contribution, in kinetic terms, of its particular components (such as: root, gravel and water) combined with bacteria is almost nonexistent.In the present study, a phenol degrader bacterium identified as Pseudomonas pseudoalcaligenes was isolated from a constructed wetland, and used in an experimental set-up containing: plants and gravel. Phenol removal rate by planktonic and biofilm bacteria (on sterile Zea mays roots and gravel surfaces) was studied. Specific phenol removal rates revealed significant advantage of planktonic cells (1.04 × 10⁻⁹ mg phenol/CFU/h) compared to root and gravel biofilms: 4.59 × 10⁻¹¹-2.04 × 10⁻¹⁰ and 8.04 × 10⁻¹¹-4.39 × 10⁻¹⁰ (mg phenol/CFU/h), respectively.In batch cultures, phenol biodegradation kinetic parameters were determined by biomass growth rates and phenol removal as a function of time. Based on Haldane equation, kinetic constants such as μ_max = 1.15/h, K_s = 35.4 mg/L and K_i = 198.6 mg/L fit well phenol removal by P. pseudoalcaligenes.Although P. pseudoalcaligenes planktonic cells showed the highest phenol removal rate, in constructed wetland systems and especially in those with sub-surface flow, it is expected that surface associated microorganisms (biofilms) will provide a much higher contribution in phenol and other organics removal, due to greater bacterial biomass.Factors affecting the performance of planktonic vs. biofilm bacteria in sub-surface flow constructed wetlands are further discussed.