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Introduction: Ethnic identity is an important protective factor for various ethnic groups and developmental periods. Although existing measures assessing ethnic identity are well known, less is known about the measurement invariance of the Multigroup Ethnic Identity Measure (MEIM) across adolescent ethnic groups. The present study evaluates the factor structure of MEIM (Roberts et al., 1999) and tests the measurement invariance across early and middle adolescence and ethnic background (N = 4940).Methods: Data from an ethnic minority sample of youth (54% girls; Mage = 13.88, grades 6th - 12th; 60% African American, 22% multi-ethnic, 8% Latinx, 5% Asian, 5% American Indian) in the United States of America were examined using confirmatory factor analysis (CFA) and multi-group measurement invariance via a structural equation modeling (SEM) framework. Models for invariance were tested using full information maximum likelihood-robust (FIML-R) estimation in Mplus.Results: CFA supported a three-factor solution (i.e., cognitive clarity, behavioral engagement, and affective pride). The model indicated scalar invariance across early and middle adolescence and partial scalar invariance across the five self-identified racial/ethnic minority groups. There were no grade differences on the ethnic identity factors. Among the racial/ethnic groups, multi-ethnic youth reported the lowest levels on all three ethnic identity factors compared to the other groups.Conclusions: Results of this study point to the validity of using the MEIM for meaningful comparisons of ethnic identity across ethnic groups and across early and middle adolescence. Implications for the interpretation and use of this measure with diverse adolescents are discussed. [ABSTRACT FROM AUTHOR]

The spores of 11 species of Lomariocycas that grow in America were studied: Lomariocycas aurata , L. columbiensis , L. cycadifolia , L. insularis , L. magellanica , L. moritziana , L. rufa, L. schomburgkii, L. shaferi , L. underwoodiana and L. werckleana. The study was performed with light microscope (LM), scanning electron microscope (SEM) and transmission electron microscope (TEM). The spores are monolete of 61–100 μm in equatorial diameter and 40–79 μm in polar diameter. The exospore is 1.5–4.8 μm thick and in section is two-layered. The perispore is folded, two types of folds were observed in the different species analyzed and also they could be fused in different ways. In section, it is 0.5–13.8 μm thick and is two-layered. The outer layer is single stratified and the inner layer is three-stratified. The spores of some species are illustrated and described for the first time. Moreover, the sporoderm ultrastructure of L. underwodiana was not studied until now. The differences found in perispore morphology and ultrastructure could be valuable characters for systematic and phylogenetic purposes. • The spores of Lomariocycas from America are folded. • Two types of folds are defined: (1) narrow and high, (2) wide and robust. • The two types of folds could be partially or totally fused. • The spores of some species are illustrated and described for the first time. • In the species analyzed the sporoderm ultrastructure is similar. [ABSTRACT FROM AUTHOR]

The extinct organic-walled dinoflagellate cyst Duosphaeridium rugosum was first described from the Paleocene (Danian) of the southern USA. It has since been documented at several other localities around the world. Well-preserved specimens from the Danian of the Dakhla Formation in the Dababiya Corehole in southern Egypt, illustrated by light and scanning electron microscope images, reveal new morphological details, most notably parasutural features revealing the paratabulation. Detailed observations indicate that Duosphaeridium rugosum has an L-type ventral arrangement, an essentially straight sulcus, and apparently dextral torsion indicating a tentative affinity with the gonyaulacacean subfamily Cribroperidinioideae. Duosphaeridium rugosum occurs in an assemblage with many Danian markers; such as Danea californica, Carpatella cornuta and Lanternosphaeridium reinhardtii. Its earliest or first occurrence is contemporaneous with the upper part of nannoplankton zone NP2 and the uppermost part of the planktonic foraminiferal Parasubbotina pseudobulloides (P1a) zone. Its first occurrence is thus a useful stratigraphical marker for the Danian (earliest Paleocene). Duosphaeridium rugosum is associated with relatively abundant dinoflagellate cyst taxa such as Spiniferites, Achomosphaera, Fibrocysta, Pterodinium, Cordosphaeridium and Exochosphaeridium, which characterize neritic marine settings. [ABSTRACT FROM AUTHOR]

Background. The accessibility of the remineralizing ions in teeth's environment is essential for their incorporation into caries-affected dentin. Novel bioglass-reinforced materials capable of releasing fluoride, calcium and phosphates may be particularly useful in the tissue remineralization process. A novel restorative material, ACTIVA BioActive-Restorative (Pulpdent Corp., Watertown, USA), is a hydrophilic resin-modified glassionomer cement (RMGIC) enriched with bioglass particles and fortified with a patented rubberized polymer resin. Its application in restorative dentistry may be significant, promoting remineralization of carious lesions. Objectives. The aim of the study was to compare the fluoride ion release profiles from a bioglass-reinforced RMGIC, a conventional glass-ionomer cement (GIC) and a nanohybrid restorative polymer resin. Material and methods. The quantity of fluoride ions released from ACTIVA, Ketac Molar Quick Aplicap and Tetric EvoCeram was assessed using a fluoride-specific electrode. The surface characteristics of the preand post-experimental specimens were studied using a scanning electron microscope (SEM) and confocal microscope. An X-ray powder diffraction (XRD) analysis was additionally used to examine the chemical compositions of the dental materials. Results. The greatest quantity of fluoride ions was freed from the GIC specimens (20.698-54.118 ppm), followed by the bioglass-reinforced RMGIC (from 1.236 to 15.552 ppm) and nanohybrid polymer resin (0.370-1.148 ppm). The pre-experimental specimens of the bioglass-reinforced RMGIC were porous, while the post-experimental specimens were smoother with visible micro-cracks. The XRD analysis of the bioglass particles confirmed that the material was composed mainly of fluoride (27.70 mass%), silicon (15.62 mass%), aluminum (5.91 mass%), and calcium (5.40 mass%). Conclusions. The fluoride ion release profile of ACTIVA was lower than the GIC Keta Molar Quick Aplicap, but significantly higher than the nanohybrid restorative polymer resin Tetric EvoCeram. [ABSTRACT FROM AUTHOR]

Aim: In vitro evaluation of shear bond strength of composite resin bonded to primary enamel which is pretreated using acid etching and E, Cr:YSGG Laser. Qualitative morphological changes in enamel surfaces were observed under a scanning electron microscope. Materials and Method: Sixty extracted human teeth were divided into two groups of 30 each (Groups A and B). In Group A, prepared surface of enamel was etched using 35% phosphoric acid (Scotchbond Multipurpose 3M ESPE). In Group B, enamel surface was etched using Er, Cr:YSGG Laser beam (Waterlase MD, Biolase, San Clemente,USA). Bonding agent (Adper, single bond 2, 3M ESPE) was applied over the test areas on 20 samples of Groups A and Groups B each light cured. Composite resin core ( Filtek z350 XT, 3M ESPE) was made in increments and light cured. The samples were tested for shear bond strength. Remaining 10 samples from each Group were observed under SEM. Results: The mean shear bond strength with standard deviation values of Group A (18.39 ± 4.75 MPa) and Group B (6.37 ± 2.71 MPa) respectively. Conclusions: Mean shear bond strength of Group A (Acid etching) was significantly higher than the mean shear bond strength of Group B (Laser etching). SEM observations of laser pretreatment showed microretentive surface with the presence of elevations and depressions not adequate to improve the bond strength as compared to Acid etching [ABSTRACT FROM AUTHOR]

Aim: The aim of this study was to compare the effect of diode laser, endoActivator, and passive ultrasonics for smear layer removal at the apical third from root canals with 0.2% chitosan. Materials and Methods: A total of 40 mandibular premolars were decoronated to establish a working length of 12 mm and shaped with ProTaper rotary files up to size F3. In Group A, canals were irrigated with 1 ml of 0.2% chitosan. In Group B, canals were initially irrigated with 0.8 ml of 0.2% chitosan and the remaining 0.2 ml was activated with diode laser. In Group C, canals were irrigated with 1 ml of 0.2% chitosan which was activated with endoActivator. In Group D, canals were irrigated with 0.2% chitosan and activated with passive ultrasonics. All samples were finally flushed with 3 ml of distilled water. The percentage of smear layer removal was analyzed with a scanning electron microscope examination at ×1000 and ×3000. Data were analyzed using Statistical Package for the Social Sciences version 16.0 (SPSS Inc., Chicago, IL, USA) at a significance level of P < 0.05. Results: The mean value for Group B when compared to Group C for the removal of smear layer was higher, but there was no statistically significant difference between the two groups (P < 0.068 and P < 0.295). Both Group B and Group C showed a statistically significant difference (P < 0.001) when compared to Group A and Group D for the removal of smear layer. Conclusion: Diode laser and endoActivator with 0.2% chitosan proved better in the removal of the smear layer when compared to passive ultrasonic irrigation. [ABSTRACT FROM AUTHOR]

The laccate (shiny or varnished) Ganoderma contain fungi that are important wood decay fungi of living trees and decomposers of woody debris. They are also an important group of fungi for their degradative enzymes and bioprocessing potential. Laboratory decay microcosms (LDMs) were used to study the relative decay ability of G anoderma curtisii, Ganoderma meredithiae, Ganoderma sessile, and G anoderma zonatum, which are four commonly encountered Ganoderma species in the U.S., across four wood types ( Pinus taeda, Quercus nigra, Q uercus virginiana, and Sabal palmetto ). Generally, all Ganoderma species were able to decay all types of wood tested despite not being associated with only certain wood types in nature. G . sessile, on average caused the most decay across all wood types. Among the wood types tested, water oak ( Q. nigra ) had the most mass loss by all species of Ganoderma . Scanning electron microscopy was used to assess micromorphological decay patterns across all treatments. All Ganoderma species simultaneously decayed wood cells of all wood types demonstrating their ability to attack all cell wall components. However, G. zonatum caused selective delignification in some sclerenchyma fibers of the vascular bundles in palm ( S. palmetto ) as well as in fibers of water oak. In addition, G. zonatum hyphae penetrated fibers of palm and oak wood causing an unusual decay not often observed in basidiomycetes resulting in cavity formation in secondary walls. Cavities within the secondary walls of fibers gradually expanded and coalesced resulting in degradation of the S2 layer. Differences in colony growth rates were observed when Ganoderma species were grown on medium amended with water soluble sapwood extracts from each wood type. G. meredithiae had enhanced growth on all media amended with sapwood extracts, while G. curtisii, G. sessile and G. zonatum had slower growth on loblolly pine extract amended medium. [ABSTRACT FROM AUTHOR]

Highlights: [•] Plastic pollution accumulates in the Laurentian Great Lakes of the United States. [•] Using SEM/EDS, misidentification of coal ash as microplastic was corrected. [•] Microplastics from the Great Lakes are suspected to be microbeads. [ABSTRACT FROM AUTHOR]

Through a combination of SEM-EDS technique could study a fragment of tattooed and non tattooed skin of the Lady of Cao, a woman of high social class Moche (Mochica early). EDS probe applied to the area with tattoo indicates the use of ferrous oxide (FeO). According to the information and finding archaeobotany tattooed mummies are holding fruits of "Jagua" Genipa americana L., is possible that this fruit of wild origin have served as raw material for use in tattooing the Lady of Cao. [ABSTRACT FROM AUTHOR]

Examination of perianal folds of stinkpot turtles, Sternotherus odoratus, from Virginia, USA, revealed several monhysterid nematodes. The general morphological characteristics of this population, such as circular amphids, unstriated cuticle under light microscope, single outstretched ovary, single testis, caudal glands, terminal spinneret and the absence of an apophysis on the gubernaculum, with the exception of the position of the gonad in relation to the intestine, shows the affinity of this population to the Monhysteridae. Microscopic observations of the inner stoma show three (one dorsal and two ventro-sublateral) buccal wall extensions towards the lumen and numerous (ca 50) distinct denticles on its wall. Because this stoma structure is a morphological novelty within the Monhysterida and this is the first monhysterid group associated with perianal folds of turtles, we propose to establish Testudinema n. gen. within the Monhysteridae to accommodate this morphologically distinct population. We provide a detailed comparison with known monhysterid genera including those that possess a cup-shaped stoma, stoma with denticles or those genera reported to be commensals (Gammarinema, Monhystrium, Tripylium, Odontobius). Stinkpot turtles feed on benthic fauna and may acquire these commensals when the sediment is disturbed. The denticles and structure of the buccal cavity could be morphological adaptations for transition to ecto-parasitism. [ABSTRACT FROM AUTHOR]

The article presents a study on the combined application of quantitative evaluation of mineralogy by scanning electron microscope (QEM-SEM) and hard X-ray microscopy to determine mineralogical associations and chemical speciation of trace metals in the U.S. It notes the reliance of successful trace metal speciation in heterogeneous matrices on a combination of techniques including spectroscopy, microscopy and wet chemical and physical experiments. It highlights the detailed insights provided by the QEM-SEM with micro-focused X-ray diffraction into the composition of mineral assemblages and their effect on trace metal speciation.

The article presents a study on the applications of differential individual particle analysis (DIPA) in particulate matter characterization in the U.S. It notes the permission of in situ DIPA on the same particles to be analyzed in the scanning electron microscope (SEM) before and after modification. However, it highlights the efficiency of the operator-controlled and computer-controlled scanning electron microscopy (CCSEM) approach because of recent developments in silicon drift detectors which have increased the speed of characteristic X-rays detection and very large numbers of particles can be analyzed in a short period of time.

Quantitative X-ray microanalysis of thick samples is usually performed by measuring the characteristic X-ray intensities of each element in a sample and in corresponding standards. The ratio of the measured intensities from the unknown material to that from the standard is related to the concentration using the ZAF or φ(ρz) equations. Under optimal conditions, accuracies approaching 1% are possible. However, all the experimental conditions must remain the same during the sample and standard measurements. This is not possible with cold field emission scanning electron microscopes (FE-SEMs) where beam current can fluctuate around 5% in its stable regime. Very little work has been done on variable beam current conditions (Griffin, B.J. & Nockolds, C.E., Scanning 13, 307-312, 1991), and none relating to cold FE-SEM applications. To address this issue, a new method was developed using a single spectral measurement. It is similar in approach to the Cliff-Lorimer method developed for the analytical transmission electron microscope. However, corrections are made for X rays generated from thick specimens using the ratio of the characteristic X-ray intensities of two elements in the same material. The proposed method utilizes the ratio of the intensity of a characteristic X-ray normalized by the sum of X-ray intensities of all the elements measured for the sample, which should also reduce the amplitude of error propagation. Uncertainties in the physical parameters of X-ray generation are corrected using a calibration factor that must be previously acquired or calculated. As an example, when this method was applied to the calculation of the composition of Au-Cu National Institute of Standards and Technology standards measured with a cold field emission source SEM, relative accuracies better than 5% were obtained. [ABSTRACT FROM AUTHOR]

The aim of the study was to compare the clinical performance, quantitative and qualitative wear patterns of conventional hybrid (Tetric Ceram), micro-filled hybrid (Gradia Direct Posterior) and nano-hybrid (Tetric EvoCeram, TEC) posterior composite restorations in a 3-year randomised clinical trial. Sixteen Tetric Ceram, 17 TEC and 16 Gradia Direct Posterior restorations were placed in human molars and evaluated at baseline, 6, 12, 24 and 36 months of clinical service according to US Public Health Service criteria. The gypsum replicas at each recall were used for 3D laser scanning to quantify wear, and the epoxy resin replicas were observed under scanning electron microscope to study the qualitative wear patterns. After 3 years of clinical service, the three hybrid restorative materials performed clinically well in posterior cavities. Within the observation period, the nano-hybrid and micro-hybrid restorations evolved better in polishability with improved surface gloss retention than the conventional hybrid counterpart. The three hybrid composites showed enamel-like vertical wear and cavity-size dependant volume loss magnitude. Qualitatively, while the micro-filled and nano-hybrid composite restorations exhibited signs of fatigue similar to the conventional hybrid composite restorations at heavy occlusal contact area, their light occlusal contact areas showed less surface pitting after 3 years of clinical service. [ABSTRACT FROM AUTHOR]

Abrading artifacts made of vesicular (porous) rock are not uncommon at archaeological sites along the Missouri River and adjacent areas. Various terms have been used to describe this material including pumice, scoria, clinker, and floatstone. Each of these terms implies different geologic origins (volcanic vs. non-volcanic) and affects interpretation of the potential modes of transport. Identification of the source area of these materials may provide significant information regarding past human movements and activities. This study focuses on vesicular artifacts in the central Plains and in particular from the Leary site (25RH1) in the southeastern corner of Nebraska. Scanning Electron Microscopy (SEM) was used to identify the chemical compositions of a subset of the Leary artifacts and comparative geologic samples of volcanic and metasedimentary origin. The results imply that the Leary (and likely many other) vesicular artifacts from the central Plains are non-volcanic in origin. The raw material from which these artifacts were made is more properly termed "paralava" and derives from outcrops in the northern Plains. Historical documents suggest that this buoyant material was transported naturally by the Missouri River as "floatstone". [ABSTRACT FROM AUTHOR]

Abstract: Age determination of single plutonium particles was demonstrated using five particles of the standard reference material, NBS 947 (Plutonium Isotopic Standard. National Bureau of Standards, Washington, D.C. 20234, August 19, 1982, currently distributed as NBL CRM-137) and the radioactive decay of 241Pu into 241Am. The elemental ratio of Am/Pu in Pu particles found on a carbon planchet was measured by wavelength dispersive X-ray spectrometry (WDX) coupled to a scanning electron microscope (SEM). After the WDX measurement, each plutonium particle, with an average size of a few μm, was picked up and relocated to a silicon wafer inside the SEM chamber using a micromanipulator. The silicon wafer was then transferred to a quartz tube for dissolution in an acid solution prior to chemical separation. After the Pu was chemically separated from Am and U, the isotopic ratios of Pu (240Pu/239Pu, 241Pu/239Pu and 242Pu/239Pu) were measured with a thermal ionization mass spectrometer (TIMS) for the calculation of Pu age. The age of particles determined in this study was in good agreement with the expected age (35.9 a) of NBS 947 within the measurement uncertainty. [Copyright &y& Elsevier]

Abstract: Naturally weathered feldspar surfaces in the Jurassic Navajo Sandstone at Black Mesa, Arizona, was characterized with high-resolution transmission and analytical electron microscope (HRTEM-AEM) and field emission gun scanning electron microscope (FEG-SEM). Here, we report the first HRTEM observation of a 10-nm thick amorphous layer on naturally weathered K-feldspar in currently slightly alkaline groundwater. The amorphous layer is probably deficient in K and enriched in Si. In addition to the amorphous layer, the feldspar surfaces are also partially coated with tightly adhered kaolin platelets. Outside of the kaolin coatings, feldspar grains are covered with a continuous 3–5μm thick layer of authigenic smectite, which also coats quartz and other sediment grains. Authigenic K-feldspar overgrowth and etch pits were also found on feldspar grains. These characteristics of the aged feldspar surfaces accentuate the differences in reactivity between the freshly ground feldspar powders used in laboratory experiments and feldspar grains in natural systems, and may partially contribute to the commonly observed apparent laboratory-field dissolution rate discrepancy. At Black Mesa, feldspars in the Navajo Sandstone are dissolving at ∼105 times slower than laboratory rate at comparable temperature and pH under far from equilibrium condition. The tightly adhered kaolin platelets reduce the feldspar reactive surface area, and the authigenic K-feldspar overgrowth reduces the feldspar reactivity. However, the continuous smectite coating layer does not appear to constitute a diffusion barrier. The exact role of the amorphous layer on feldspar dissolution kinetics depends on the origin of the layer (leached layer versus re-precipitated silica), which is uncertain at present. However, the nanometer thin layer can be detected only with HRTEM, and thus our study raises the possibility of its wide occurrence in geological systems. Rate laws and proposed mechanisms should consider the possibility of this amorphous layer on feldspar surface. [Copyright &y& Elsevier]

Phenolic resins, phenol-formaldehyde polymers previously thought to be nonbiodegradable, are produced at an annual rate of 2.2 million metric tons in the United States for many industrial and commercial applications. Three independent lines of evidence established their biodegradability with the white-rot fungus Phanerochaete chrysosporium. Chromatic transformation of growth medium (yellow to pink) indicated initial biodegradation of the resin 3 days after inoculation. A degradation product, 13C -labeled phenol, was detected with gas chromatography—mass spectroscopy. Scanning electron micrographs revealed physical evidence of degradation. This is the first demonstrated biodegradation of these phenol—formaldehyde polymers and stands as a platform for investigation into bioremediation and biorecycling of phenolic resins. [ABSTRACT FROM AUTHOR]

Building and evaluating artifacts specifically for K-12 education, technologists committed to design sciences are needed along with an approach to evaluation increasing the systemic transfer from research and development into school settings. The authors describe THE VIRTUAL LAB scanning electronic microscope simulation, including (a) its development from a design and project management perspective at NASA and (b) the formative evaluation, drawing on a usability study conducted in high school science classrooms by University of Central Florida. The authors offer a four-level assessment that begins with the overarching vision that guided developers. Over time, a team of evaluators (a) verify (the artifact), (b) check variation (of content), (c) verify (in context), and (d) document value (in the field of education). THE VIRTUAL LAB usability study is offered as a specific example in the evaluation process using both quantitative and qualitative data while responding and contributing to an overarching vision for education. [ABSTRACT FROM AUTHOR]

Abstract: Recently, there have been several occurrences of failure in the bolt of the Ml6 rifle at a United States Army installation. Near the failure location, the bolt was subjected to repeated loading as the Ml6 was fired. In order to determine the stress distribution of the bolt due to the firing process, a geometric element analysis was performed using ProMechanica®. The fracture surface was examined using both an optical stereomicroscope and a scanning electron microscope in order to determine failure initiation and failure mode. It was discovered that the fracture initiated at a localized corrosion pit and propagated by fatigue. A controlled experiment was conducted where 1800 and 3600 rounds were fired using new bolts. After 1800 rounds, a region of wear was observed near the site where fracture occurred in the failed bolt. After 3600 rounds, a notch was observed in this wear region. This suggests two possibilities: firstly, exposure of the base metal may have facilitated the formation of the observed corrosion pits; and secondly, the presence of a notch may facilitate the fracture of bolts in general. In addition, Vickers microhardness profiles were taken on cross-sectional areas near the fillet region and 10mm away from the failed locking lug. Disparities between microhardness profiles near the fillet region and 10mm away from this region revealed that the bolt may not have been uniformly case hardened. [Copyright &y& Elsevier]

The National Institute of Standard and Technology (NIST) is developing single-crystal reference materials for use as critical dimension (CD) reference materials. In earlier work, the reference features on these reference materials have been in the device layer of a silicon-on-insulator (SOI) wafers, with the buried oxide providing electrical isolation. This paper describes a new method of Slating the structures from the substrate by mews of a pn junction. The junction isolation technique is expected to provide several advantages over the SOI technique Including minimal susceptibility to charging when imaged in a CD scanning electron microscope (CDSEM), better edge quality, and ease of manufacture. Primary calibration of these reference materials is by imaging the cross-section of the feature with high-resolution transmission electron microscopy (HRTEM) at sufficiently high energy to resolve and count the individual lattice planes while electrical test structure metrology techniques provide the transfer calibration. Secondary calibration is performed with electrical test structure metrology, supplemented by visual techniques to verify that the features meet uniformity requirements. In this paper, we describe results for determining the electrical critical dimensions of these junction-isolated structures. This measurement and data analysis technique is a unique combination of the short-bridge variation of the cross-bridge resistor and the multi-bridge structure. [ABSTRACT FROM AUTHOR]

This article presents technical abstracts and notes related to police science. The article "Forensic Applications of the Scanning Electron Microscope," by I. Covin and O. Jahari, presents the proceedings of a forensic workshop held in May, 1971. The article " The Status of Polygraph Legislation of the Fifty States," by Clarence H.A. Romig, discusses the history of the polygraph, the physiological and psychological aspects involved, and the legal status of the polygraph in the United States; part two of this paper continues with the various uses being discussed and concludes by presenting both sides of the argument over the use of the polygraph. The concluding segment covers legislation affecting the use of the polygraph including licensing legislation in eleven states. The series is concluded with a model set of minimum standards for operator certification and regulation. The article " Ubiquitous Reds: A Local Perspective on Secobarbital Abuse," by Bryan S. Finkle, discusses the social background and results of a study and evaluation of secobarbital abuse in Santa Clara County, California. The study also reports the results of analytical analysis showing great variations of the secobarbital content of capsules and also shows that the blood levels are significantly in excess of therapeutic levels which is a possible explanation for a rapid use in secobarbital fatalities among young people and the drug involvement in road traffic accidents.

This article offers news briefs related to the field of science and technology. For more than 2 decades, photomicroscopist Dee Breger of Drexel University in Philadelphia, Pennsylvania, has used artistic photographs from scanning electron microscopes (SEM) to lure the public into learning about science. Last fall, she offered an hour-long guided session on an SEM as part of an auction to raise money for educational software. The auction, organized by Galaxygoo, a San Francisco nonprofit, featured works of art inspired by science, including Breger's own SEM image of a penguin feather. In 2000, Aristides Patrinos brokered a truce between a U.S. government project to sequence the human genome and a competing, private effort led by J. Craig Venter. Now, the 59-year-old engineer-turned-science administrator is leaving the Department of Energy after 3 decades to run a company founded by Venter. Great Britain's Nicholas Shackleton died on January 24, 2006. He started out studying physics, switched to measuring minuscule isotopic differences in microscopic bits of ocean mud, and ended up establishing the metronomic qualities of climate change.

Polyacrylamide (PAM) is used at rates of 1 to 2 kg ha-1 per irrigation on a half million hectares of United States irrigated farmland to prevent 94% of irrigation-induced erosion and to enhance infiltration by 15% to 50% on medium to fine-textured soils. The polyacrylamides used for this application are large (12 to 15 megagrams per mole), water-soluble anion molecules applied in the irrigation stream. Erosion prevention has been shown to result from stabilized soil structure in the 1 to 5 mm veneer of surface soil that regulates infiltration, runoff, and sediment loss on water application. We hypothesized that this could be confirmed from scanning electron micrographs (SEMs) of PAM-treated soil. Both untreated and PAM-treated soils form surface seals in irrigation furrows, but the stable surface structure of PAM-treated furrows is more pervious. This is thought to result from a greater number of continuous unblocked pores at the soil-water interface. SEMs of PAM-treated and untreated soil microstructures are presented from thin surface samples of Portneuf silt loam, collected from furrows immediately following an irrigation, and freeze-dried. SEMs of PAM-treated soil showed net or web-like microstructural surface coatings about 1 mm thick on soil mineral particles, giving a glue-like porous appearance. Individual strands of PAM were about 0.2 mm in diameter. Strands of PAM aggregated the soil by ensnaring and bridging mineral particles while untreated soil had poorly aggregated, unconnected particles. Thus, microstructural differences between PAM-treated and untreated soil from irrigation furrows were consistent with erosion and infiltration results. [ABSTRACT FROM AUTHOR]