cssi/SciSciGPT-SciSciNet huggingface dataset:
The Mll2 branch of the COMPASS family regulates bivalent promoters in mouse embryonic stem cells.

Embryonic stem cells (ESCs) possess a unique chromatin landscape in which 'bivalent' domains of trimethylated histone H3 Lys4 (H3K4me3) and Lys27 (H3K27me3) mark key lineage-specific genes. A new study now reports the identification of Mll2 (KMT2b) as the enzyme responsible for implementing H3K4me3 on bivalently marked promoters in ESCs. Promoters of many developmentally regulated genes, in the embryonic stem cell state, have a bivalent mark of H3K27me3 and H3K4me3, proposed to confer precise temporal activation upon differentiation. Although Polycomb repressive complex 2 is known to implement H3K27 trimethylation, the COMPASS family member responsible for H3K4me3 at bivalently marked promoters was previously unknown. Here, we identify Mll2 (KMT2b) as the enzyme catalyzing H3K4 trimethylation at bivalentlymarked promoters in embryonic stem cells. Although H3K4me3 at bivalent genes is proposed to prime future activation, we detected no substantial defect in rapid transcriptional induction after retinoic acid treatment in Mll2-depleted cells. Our identification of the Mll2 complex as the COMPASS family member responsible for H3K4me3 marking bivalent promoters provides an opportunity to reevaluate and experimentally test models for the function of bivalency in the embryonic stem cell state and in differentiation.
Thermally Controlled Crystallization of Electrospun TiO2 Nanofibers

The anatase phase of TiO2 has been of great interest due to its photocatalytic activity. For enhanced photocatalytic activity, the polymorphic structure of anatase phase and the rutile phase was pursued to form the semiconductor-semiconductor junction, which could even further enhance photocatalytic activity. TiO2 nanofibers with large specific surface area were fabricated via electrospinning from ethanol-based sol while the phase development was controlled by heat treatment. TiO2 fibers were characterized by x-ray diffraction (XRD) and transmission electron microscopy (TEM) for the crystalline phase and its microstructure, respectively. Among different heat treatment temperatures tested, 700°C was found to have the smallest grains while having both semiconductor, i.e. rutile and anatase available. TiO2 calcined at 800°C also achieved the polymorphic structure of anatase and rutile phases, however showed significant grain growth.
Photolithographic Imaging of Planar Optical Waveguides and Integrated Optic Devices onto Porous Silicate Glasses and Silica Sol-Gels

The success of photonic switching depends on the development of materials capable of processing light signals without the interweaving conversion to electronic signals. The photodeposition of metal oxides onto porous Vycor glass and silica glass sol-gels produce changes in the index of refraction of the glass of the order of 0.1 to 0.001. Nonlinearities in transmission and refractive index allow the deposition of 1.0-10.0 μm width planar waveguides with attenuations of 0.6 dB/cm. This technique is being evaluated for the optical performance of couplers, dividers, and interferometers. Also 3-dimmensional interactive planar waveguide structures are being fabricated in silica sol-gel thin-films.
OPERATOR FORMALISM FOR DAUGHTER TRAJECTORIES IN THE BETHE-SALPETER EQUATION.

The existence of daughter Regge poles is demonstrated by a raising and lowering operator formalism without explicit use of $O(4)$ symmetry. The commutation relations of these operators with the kernel of the Bathe-Salpeter integral equation require the existence of the degeneracy which leads to an infinite chain of daughter Regge trajectories. It is found that the chain of daughter poles does not terminate even if the parent pole is at a positive integer. A formula is given for calculating the slopes of the Regge trajectories.
Pixel-by-pixel aberration correction for scanned-beam micro-optical instruments

Variable aberration compensation elements designed to correct the primary aberrations, and capable of sufficient speed for on-the-fly correction, can significantly extend the diffraction-limited field of view of scanned-beam instruments using practical microlens systems. In this paper we review the relevant aberration theory and discuss the requirements for compensation elements as well as appropriate architectures for correction of a scanned-beam instrument. We report correction of astigmatism and field curvature in an F/20 optical system using deformable polysilicon reflective membranes. Devices were successfully demonstrated that compensated more than 1.5 waves of defocus and more than 1 wave of astigmatism with less than 1/10 wave of spherical aberration, and with a bandwidth in excess of 20 kHz, which is suitable for high speed beam scanning applications such as video-rate imaging.
The democratic peace research program and system-level analysis

In a path-breaking article, Wade Huntley reinterpreted Kant’s pacific union as a systemic phenomenon. This generated a new wave of inquiry into the evolutionary expansion of the democratic peace. The resulting literature examines how the effects of the pacific union vary over time and with the strength of the global democratic community. It investigates the possibility that the democratic zone of peace may spread through spillover effects, socialization dynamics, and positive feedback. In so doing, it has moved democratic peace research beyond the ‘separate peace’ formulation. Currently, however, this literature has accumulated insights on an ad hoc basis. New hypotheses have been developed and tested without systematically considering how these insights contribute to established knowledge about the democratic peace. This article uses philosophy of science criteria to assess the contributions of the systemic democratic peace literature. It shows how systemic analysis of the democratic peace is progressive in terms of Lakatos’s methodology of scientific research programs. The article first considers how Lakatosian methodology has been applied to dyadic democratic peace research. Next, it refines this account of the democratic peace research program to make it more suitable for evaluating the contributions of the systemic literature. The last section shows systemic analysis is compatible with the Lakatosian vision of a cumulative series of theories (monadic-dyadic-systemic) building logically from a core assumption. It then uses the established structure of dyadic inquiry to frame a wide-ranging agenda for a second generation of democratic peace studies.
The Role of Histone Acetylation in Memory Formation and Cognitive Impairments

Long-term memory formation requires transcription and protein synthesis. Over the past few decades, a great amount of knowledge has been gained regarding the molecular players that regulate the transcriptional program linked to memory consolidation. Epigenetic mechanisms have been shown to be essential for the regulation of neuronal gene expression, and histone acetylation has been one of the most studied and best characterized. In this review, we summarize the lines of evidence that have shown the relevance of histone acetylation in memory in both physiological and pathological conditions. Great advances have been made in identifying the writers and erasers of histone acetylation marks during learning. However, the identities of the upstream regulators and downstream targets that mediate the effect of changes in histone acetylation during memory consolidation remain restricted to a handful of molecules. We outline a general model by which corepressors and coactivators regulate histone acetylation during memory storage and discuss how the recent advances in high-throughput sequencing have the potential to radically change our understanding of how epigenetic control operates in the brain.
The development of a refractory state to adrenocorticotrophic hormone.

In view of current interest in adrenocorticotrophic hormone (ACTH) and its widespread experimental use in the clinic and laboratory, it seemed pertinent to determine whether animals remain responsive or become refractory to repeated injections of this substance. Interest in the development of “antihormones” dates to the work of Collip andAnderson (1934). It is nowr well-known that the injection of pituitary thyrotrophic hormone orthe gonadotrophic hormones of the pituitary or of the chorionic tissues readily induces in animals of heterologous species a refractory state associated with demonstrable antihormones in the serum. Similar, though less wrell-established, evidence has been presented concerning almost every principle elaborated by the anterior pituitary. Although the nature of the antihormones has not been definitely established, most of the evidence suggests that they behave, for the most part, as antibodies. Thus, it has been shown that (1) certain of the trophic hormones of the pituitary and cho...
Composite pattern structured light projection for human computer interaction in space

Interacting with computer technology while wearing a space suit is difficult at best. We present a sensor that can interpret body gestures in 3-Dimensions. Having the depth dimension allows simple thresholding to isolate the hands as well as use their positioning and orientation as input controls to digital devices such as computers and/or robotic devices. Structured light pattern projection is a well known method of accurately extracting 3-Dimensional information of a scene. Traditional structured light methods require several different patterns to recover the depth, without ambiguity and albedo sensitivity, and are corrupted by object motion during the projection/capture process. The authors have developed a methodology for combining multiple patterns into a single composite pattern by using 2-Dimensional spatial modulation techniques. A single composite pattern projection does not require synchronization with the camera so the data acquisition rate is only limited by the video rate. We have incorporated dynamic programming to greatly improve the resolution of the scan. Other applications include machine vision, remote controlled robotic interfacing in space, advanced cockpit controls and computer interfacing for the disabled. We will present performance analysis, experimental results and video examples.
Selective coulometric release of ions from ion selective polymeric membranes for calibration-free titrations

Coulometry belongs to one of the few known calibration-free techniques and is therefore highly attractive for chemical analysis. Titrations performed by the coulometric generation of reactants is a well-known approach in electrochemistry, but suffers from limited selectivity and is therefore not generally suited for samples of varying or unknown composition. Here, the selective coulometric release of ionic reagents from ion-selective polymeric membrane materials ordinarily used for the fabrication of ion-selective electrodes is described. The selectivity of such membranes can be tuned to a significant extent by the type and concentration of ionophore and lipophilic ion-exchanger and is today well understood. An anodic current of fixed magnitude and duration may be imposed across such a membrane to release a defined quantity of ions with high selectivity and precision. Since the applied current relates to a defined ion flux, a variety of non-redox active ions may be accurately released with this technique. In this work, the released titrant's activity was measured with a second ionophore-based ion-selective electrode and corresponded well with expected dosage levels on the basis of Faraday's law of electrolysis. Initial examples of coulometric titrations explored here include the release of calcium ions for complexometric titrations, including back titrations, and the release of barium ions to determine sulfate.
Challenging, eye-opening, and changing U.S. teacher training in Korea: Creating experiences that will enhance global perspectives

This case study explored the short-term international experience of preservice teachers to create and enhance global perspectives. These teachers (n=5), all female graduate students at a university in the U.S., were fully immersed in a foreign culture for three weeks while teaching English to primary and secondary students in Korea. Pre-, during-, and post-data were collected to investigate how the participants work and live while being completely immersed in a new culture. Eight themes emerged from the analysis of multiple qualitative instruments: (a) language barrier, (b) being the minority, (c) cultural differences and cultural shock, (d) student participation and teaching methods, (e) classroom management, (f) underestimation of English language learners, (g) finding confidence as a teacher and instructional flexibility, and (h) support systems. Overall, teachers expressed a transformation in both their teaching philosophy and cultural perspectives despite the short duration of the experience. They also reported that this linguistic and cultural immersion not only advanced their global perspective but also provided them with the necessary tools and understanding to work with diverse populations more emphatically and effectively. The findings suggest that additional teacher training is needed to increase preservice teachers' cultural competence and responsiveness to better address the needs of today's diverse student populations.
A method for polarization control and analysis on Bonse-Hart double-crystal USANS instruments

The use of polarized beams and polarization analysis is an area of increasing interest to the small-angle neutron scattering (SANS) community. Since the angular acceptance of a DCD USANS instrument is very narrow, magnetic prisms can be exploited to select polarization. We compare two schemes by which this can be accomplished and describe how this method can be adapted for use on time-of-flight DCD USANS instruments. The wavelength dispersion of the prism can be used on steady-state instruments to select or suppress higher harmonics of the characteristic incident wavelength.
A microradiographic comparison of sound and carious human dental cementum

Abstract The mineral distribution in sound and carious human acellular and cellular cementum was studied by microradiography of thin sections. Observations on the sound tissue confirmed the occurrence of alternating bands of high and low mineral content and also the formation of a densely mineralized layer at the external surface of cementum exposed to the oral environment. Carious cementum showed subsurface demineralization and the frequent occurrence of a densely mineralized surface layer wider than that observed in exposed, non-carious cementum. A densely mineralized layer was frequently observed at the cemento-dentinal junction. In the central portion of the tissue two patterns of mineral distribution were noted. One of the patterns was characterized by a uniform demineralization, while the other showed radially oriented areas of marked demineralization alternating with areas of high mineral content, giving the tissue a brush-like appearance. The various changes observed were interpreted as having resulted from the processes of demineralization and remineralization.
A survey of lead battery recycling sites and soil remediation processes

Abstract This paper is intended to provide some background information on lead battery recycling sites (LBRSs) in the U.S. Included in the report are (a) a discussion of the regulations and guidelines governing lead in soil; (b) a description of typical LBRS operations; (c) a listing of the 47 sites studied by the EPA under CERCLA; (d) a discussion of a potential problem associated with the widely used remediation technique of solidification/stabilization; and (e) an overview of some innovative treatment technologies that may be used at LBRSs
Fluorescence lifetimes of vibronic levels of naphthalene vapour

Abstract Fluorescence lifetimes of single vibronic levels of naphthalene vapour have been measured as a function of energy with a resolution of 1.7 A and a new single photon-phase technique. Clear evidence of lifetime changes in vibronic progressions is observed which reveals a model for naphthalene which does not allow for communicating states.
The effect of progesterone on activities of δ-aminolevulinic acid synthetase and δ-aminolevulinic acid dehydratase in estrogen-primed avian oviduct☆

Abstract The effect of a single dose of progesterone, administered to estradiol-primed chicks, on the activities in oviduct and liver of the first two enzymes of the porphyrin-heme biosynthetic pathway, δ-aminolevulinic acid synthetase (ALAS) and δ-aminolevulinic acid dehydratase (ALAD), has been investigated. The specific activity of ALAS in pooled glandular tissue of uterus and isthmus became significantly elevated at 18–24 hr after hormone injection. ALAD activity in uterine glandular tissue was not significantly increased after such treatment. Progesterone had no effect on hepatic activities of these two enzymes.
Separation of nitramine and nitroaromatic explosives by capillary liquid chromatography

This study outlines the successful separation of nitrated explosives by using high efficiency capillary liquid chromatography. Careful optimization of separation conditions such as mobile phase composition and temperature was performed by using a window diagram, as well as a more global criterion, the chromatographic resolution statistic. These efforts resulted in complete baseline resolution of all 14 components of a standard mixture of explosives, which has not previously been achieved using conventional liquid chromatography. This method was then applied to the determination of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazine (HMX), and 2,4,6-trinitrotoluene (2,4,6-TNT) in commercial-grade and military-grade explosive samples. As a result, the countries of manufacture of two RDX samples were deduced based on the presence or absence of reaction byproducts.
Children's lunch intake: effects of midmorning snacks varying in energy density and fat content.

To determine the effects of preloads differing in energy density and fat content on subsequent lunch intake, 24 preschool children 113 g ice-cream preloads as mid-morning snacks (containing 0, 12, or 18 g of fat, and 4 g of protein), followed nearly 2 h later by an ad libitum lunch consisting of a variety of foods. A fat-free baseline preload, consisting of dry cereal and apple juice, was also included. The baseline, fat-free, medium and high-fat preloads contained 334, 740, 953, and 1150 kJ per serving. All three ice-cream preloads produced significant but equivalent suppression of ad libitum lunch intake relative to baseline; lunch intake was not related to the fat content or energy density of the ice-cream preloads. Compensation at lunch was not macronutrient specific; children did not increase their fat intake at lunch following the fat-free preload. As energy and fat content of the preloads increased, children consumed significantly fewer foods at lunch, confirming previous findings. These changes in the variety of foods consumed were related to preference: regardless of preload, children continued to consume their preferred foods, while non-preferred foods tended to be eliminated following the higher energy preloads. Because compensation for energy was incomplete, energy intake of meals plus snacks increased with the energy content of the preload. Additional research is required to determine whether manipulating the fat and energy content of snacks produces similar effects when the unit of analysis is the child's total daily diet, rather than a single meal.
Cyberinfrastructure for public health

Great strides were made during the 20th Century to improve the diagnosis and treatment of many common diseases, but those strides are not enough. Millions die each year from diseases that are chronic and complex. To meet the challenge of combating these complex diseases, biomedical research in the 21st Century must take advantage of advanced discovery in information technology to create interventions that are predictive, personalized, and preemptive. [1] At the patient level, 21st Century medicine must use the precision of evidence-based diagnostic systems to deliver highly tailored treatment regimens in precise, effective ways. At the population level, 21st Century disease control must use the power of connective surveillance infrastructures to identify targets of opportunity early, and to apply current knowledge for intervention in rapidly diffusing ways. To achieve these goals, population health in the 21st century must rely on the connective power of powerful health informatics infrastructures, or cyberinfrastructures in health.
P-type δ-doping of highly-strained VCSELs for 25 Gbps operation

We present the utilization of δ-doping to mitigate the rise in nonlinear gain compression in highly-strained InGaAs VCSELs and compare it with unstrained and undoped active region designs. High-speed 25 Gbps operation is also demonstrated.
Arfaptin 1 forms a complex with ADP‐ribosylation factor and inhibits phospholipase D

Abstract ADP-ribosylation factors (ARFs) regulate coatomer assembly on the Golgi as well as recruitment of clathrin adapter proteins and are therefore involved in vesicle budding from the Golgi and vesicular transport. They are also regulators of phospholipase D (PLD) activity. Arfaptin 1 is an ARF binding protein that inhibits PLD activation, vesicular trafficking and secretion. In the present report, we show that arfaptin 1 interacts with ‘high speed’ membranes independently of ARF. However, addition of myristoylated ARF3 (myrARF3) increases the association of arfaptin 1 with the membranes, suggesting that arfaptin 1 and ARF form a complex on the Golgi. Utilizing several deletion mutants of arfaptin 1 it is shown that the association of arfaptin 1 with myrARF3 is mediated via two binding sites on arfaptin 1. These two domains are needed for arfaptin 1 inhibition of PLD activation by myrARF3 in vitro.
A total market approach for condoms in Myanmar: the need for the private, public and socially marketed sectors to work together for a sustainable condom market for HIV prevention

Background Concerns about appropriate pricing strategies and the high market share of subsidized condoms prompted Population Services International (PSI)/Myanmar to adopt a total market approach (TMA). This article presents data on the size and composition of the Myanmar condom market, identifies inefficiencies and recommends methods for better targeting public subsidy. Methodology Data on condom need and condom use came from PSI/Myanmar’s (PSI/M’s) behavioural surveys; data for key populations’ socioeconomic status profiles came from the same surveys and the National Tuberculosis Prevalence Survey. Data on market share, volumes, value and number of condoms were from PSI/M’s quarterly retail audits and Joint United Nations Programme on HIV/AIDS (UNAIDS). Results Between 2008 and 2010, the universal need for condoms decreased from 112.9 to 98.2 million while condom use increased from 32 to 46%. Free and socially marketed condoms dominated the market (94%) in 2009–11 with an increase in the proportion of free condoms over time. The retail price of socially marketed condoms was artificially low at 44 kyats ($0.05 USD) in 2011 while the price for commercial condoms was 119–399 kyats ($0.15–$0.49 USD). Equity analyses demonstrated an equal distribution of female sex workers across national wealth quintiles, but 54% of men who have sex with men and 55% of male clients were in the highest two quintiles. Donor subsidies for condoms increased over time; from $434 000 USD in 2009 to $577 000 USD in 2011. Conclusion The market for male condoms was stagnant in Myanmar due to: limited demand for condoms among key populations, the dominance of free and socially marketed condoms on the market and a neglected commercial sector. Subsidies for socially marketed and free condoms have prevented the growth of the private sector, an unintended consequence. A TMA is needed to grow and sustain the condom market in Myanmar, which requires close co-ordination between the public, socially marketed and commercial sectors.
On solar system nomenclature

Arguments in support of naming topographic features on other solar system objects after human beings other than astronomers are outlined. In particular, it is important to make sure that the end result will be a nonprovincial distribution of nationalities, epochs, and occupations, a distribution that future generations can be proud of. A more consistent scheme for Jovian satellite nomenclature is proposed which consistently maintains the tradition of naming Jovian satellites after prominent consorts.
Exploring Network-Centric Information Architectures for Unmanned Systems Control and Data Dissemination

Abstract : The exploration and development of an information architecture for networked unmanned systems is described. The unmanned systems discussed utilize standard components for guidance and navigation, coupled with additional computing devices for interfacing with a network. These platforms in turn communicate with a broader network of devices, applications, and users via a variety of wireless network links. Networking a platform that is traditionally operated via serial control links and analog sensor downlinks provides two distinct advantages: (i) high-level control, or tasking, of the platform is easily extended from the single operator to any authorized user on the network; and (ii) sensor data and status information may be disseminated rapidly across the network to all interested recipients. The architecture developed through this exploration is applied in a prototype UAV which is utilized as both a high-resolution imaging platform and a wireless network relay. Testing and evaluation of the architecture occurs on an ongoing, quarterly basis through a cooperative field experiment program run by U.S. Special Operations Command and the Naval Postgraduate School.
Simulation tools for evaluating optical plant sensors for variable-rate application technology

A significant reduction in the amount of pesticides applied in agricultural and biological systems could be achieved using spot spray technology. To accomplish this, advanced plant sensor systems must be developed that can accurately locate and identify weeds from crop plants in the field. Currently, both public and commercial efforts have concentrated on single element optical sensors based on key reflective elements of the plant and soil system. Machine vision or image analysis is being investigated as another possible tool in plant sensing. It may provide valuable optical design information for less expensive single-element sensors. Moreover, shape features and textural analysis already provides simple broadleaf-grass classification based on staged plant images. These have not been thoroughly field tested. Another approach is to test image analysis algorithms, using three-dimensional rendering of weed and plant canopy architecture under complex lighting regimes. What was essentially done was to extract plant shape and textural information, along with essential physiological data from actual photographic images and then reassemble them as a virtual plant in the computer. A dissection program was written in C and efficiently extracts and stores irregular leaf shape and texture data. A canopy architecture program was written in C and Media Cybernetics HALOR graphics routines under DOS Expanded Memory on a personal computer. The plant simulation model consists of a three dimensional space where simulated light rays are generated as diffuse or speculative illumination. Plant surfaces are simulated with actual textural maps. The virtual plant is then manipulated to generate images that would be seen with machine vision. Computer simulated weed images were used to generate and test different fields of view sizes for evaluating how single element optical sensors would respond to composite leaf-soil reflectance.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Application of feature descriptors to low-pixel-count persistent surveillance tracking systems

The largest challenge with all persistent surveillance systems is they require a trade between area coverage and ground object resolution. This trade typically results in provision of imagery where objects desired to be tracked have a small total number of pixels (often less than a few hundred total). With such low pixel counts, traditional target recognition methods become difficult. For this reason, most persistent surveillance tracking systems are based on detection and tracking of image changes. These change-detection tracking systems, however, struggle to maintain tracks through quick maneuvers, stops, obscurations, and dense traffic. Feature descriptors, including template matching, histogram of oriented gradients (HOG), and local binary patterns (LBP) are evaluated for use in the special case of very low pixel count target detection and track maintenance. These dynamic feature-based detection models are incorporated into a change-detection based tracking system. The resulting composite tracking system will be described as applied to EO and MWIR wide area data collected under a variety of conditions. Resulting tracking system improvements and tradeoffs between feature descriptors are presented.
Wavelength selective detection using excitonic resonances in GaAs/AlGaAs P-I-(MQW)-N structures

Abstract The quantum confined Stark effect causes a strong wavelength and voltage dependence of photocurrent near excitonic resonances which is used to study the wavelength selectivity of p-i(MQW)-n photodiode. For a parallel input of optical bits each coming at a different wavelength, the selectivity is considered good if the state of a λ i wavelength bit can be detected regardless of the λ j (j ≠ i) state of the bits. Photocurrent is found to have very good selectivity if λ j bits are all zero, i.e. the optical information is serial. However, we find that differential photocurrent (Δ I ph /ΔV) provides a good selectivity for random states of λ j bits (i.e. parallel input). Four channel selectivity is demonstrated at 200K. Specially designed quantum well structures can greatly improve this selectivity.
On the origin of molecular "handedness" in living systems

Elementary particle effects (β-decay) provide at best only a weakly handed radiation in the biologically effective energy ranges. Global magnetic effects coupled to sunlight are randomized by paleomagnetic reversals. Hence a persistent terrestrial handed bias at possible local biopoetic sites offers a more promising explanation for the origin of the "handedness" of the molecules found among living systems on earth. Magnetite in lava flows maintains a handed bias for surface catalysis through many magnetic reversals. Magnetite contaminated with sulfur has already been proposed by Granick as a biopoetic site because it provides a weak source of chemical energy derived by photochemical conversion. Indirect evidence for this hypothesis has been provided by the molecular structure of ferredoxin - a single strand of the 14 primordial amino acids wrapped around an FeS core. Lava flows have been suggested as biopoetic sites by Fox, since their temperature and chemical composition might allow for the rapid synthesis of prebiotic compounds at the surface of the primitive earth. The additional fact that magnetite in lava flows also provides a persistent handed site for surface catalysis offers a further argument for the experimental investigation of this specific biopoetic environment.
What We Do and Don’t Know about Teaching and Learning Science: The National Research Council Weighs in on Discipline-Based Education Research

The National Research Council recently published a report about discipline-based education research in science and engineering. Some implications for chemical education are presented, along with the role of chemical education research in the Journal.
Optimization over the efficient set

This paper deals with the problem of maximizing a function over the efficient set of a linear multiple objective program. The approach is to formulate a biobjective program with an appropriate efficient set. The penalty function approach is motivated by an auxiliary problem due to Benson.
Scaling and Optimization of Gravure-Printed Silver Nanoparticle Lines for Printed Electronics

Printed electronics promises to enable new applications such as RFID tags, displays and various types of sensors. Critical to the development of printed electronics is the establishment of a manufacturable printing technique with high resolution and throughput. Gravure is a high-speed roll-to-roll printing technique that has many of the characteristics necessary for a viable printed electronics process. We present the first systematic study on the scaling and optimization of conductive lines for printed electronics, especially with high viscosity nanoparticle inks. We demonstrate gravure-printed nanoparticle lines, which are potentially suitable for use in thin-film transistor (TFT) based circuits as well as passive components. We present several trends observed by varying cell and ink parameters, and compare two different techniques for printing lines. We examine current limits to scaling printed lines and demonstrate the potential viability and scalability of gravure for printed electronics.
Integrin-ligarid interactions: a year in review

Many cell-cell and cell-matrix interactions depend upon the engagement of specific ligands by members of the integrin family of cell-adhesion receptors. In concert with the identification of new integrins, the number of integrin ligands continues to expand dramatically. The diversity of the integrin ligands bridges many areas of cell and molecular biology. Ligand recognition by integrins requires not only the presence of the cognate primary sequence within an appropriate secondary structure, but also the correct tertiary and quaternary structure of the ligand. Presentation of an 'activated' ligand sequence to specific contact sites within the integrin under specified divalent-cation conditions is necessary for a productive and high-affinity interaction.
Structural properties of DNA oligomers containing (GACX)(n) and (GAXC)(n) tandem repeats.

The antisense DNA sequence of mature mouse micro RNA, miR341, includes three repeats of the tetranucleotide (GACC). The -GAC- repeat is known to form a parallel duplex, in acidic environments. The thermal melting profile of miR341 DNA, at pH 4, 5, and 6 indicates the formation of a very stable structure, which loses its stability when pH is increased. Thus, the addition of a cytosine at the 3' end of the (GAC) motif preserves the molecule's potential to fold into an unusual structure at low pH. The effect of modifying the nucleotide composition of the GACC sequence on the secondary structures formed by oligomers containing seven tandem repeats of the altered motifs was examined here. UV melting profiles were determined, as a function of pH, for 28-mers of the two series (GAXC)(7) and (GACX)(7) (X= A/C/T/G)(.) The sequence (GACC)(7) was found to be extremely sensitive to pH variations, with a stable structure formed at pH 5 (T(m) ≥ 60°C). NMR spectroscopy established that the low pH structure is not B-DNA. (GACA)(7) and (GACT)(7) also formed stable structures at low pH but the addition of guanine at the 3'end, as seen in the (GACG) series resulted in the loss of this property. Introducing a break in the 5'-GAC-3' motif, explored in the (GAXC) series, also inhibits formation of stable structures under acidic conditions.
An experimental study of bubble departure diameter in subcooled flow boiling including the effects of orientation angle, subcooling, mass flux, heat flux, and pressure

Abstract The effects of orientation angle, subcooling, heat flux, mass flux, and pressure on bubble departure diameter in the isolated bubble regime of subcooled flow boiling were studied by high-speed video in a two-phase flow loop that can accommodate a wide range of flow conditions. Specifically, the following ranges were explored: orientation angles of 0° (downward-facing horizontal), 30°, 45°, 60°, 90° (vertical), and 180° (upward-facing horizontal); mass flux values of 250, 300, 350, and 400 kg/m 2 s, corresponding to Froude numbers between 0.42 and 1.06; pressures of 101 (atmospheric), 202, and 505 kPa; two values of the subcooling degrees (10 and 20 °C); and two heat fluxes (0.05 and 0.10 MW/m 2 ). The combination of the test section design, high-speed video camera and LED lighting results in high accuracy (order of 20 μm) in the determination of the bubble departure diameter. The data indicate that the bubble departure diameter increases with increasing heat flux, decreasing mass flux, decreasing subcooling, and decreasing pressure. Also, the bubble departure diameter increases with decreasing orientation angle, i.e. the largest bubbles are found to detach from a downward-facing horizontal surface. The mechanistic bubble departure diameter model of Klausner et al. and its recent modification by Yun et al. were found to correctly predict all the observed parametric trends, but with large average errors and standard deviation: 65.5 ± 75.8% for Klausner's and 37.9 ± 51.2% for Yun's. Since the cube of the bubble departure diameter is used in subcooled flow boiling heat transfer models, such large errors are clearly unacceptable, and underscore the need for more accurate bubble departure diameter models.
The singlet state photophysical behaviour of poly(bis(phenoxy)phosphazene) in solution

Abstract The fluorescence of poly(bis(phenoxy)phosphazene) (PPZ) in CH2Cl2 has been studied. Like polystyrene and other vinylaryl polymers the spectrum has a significant contribution from an excimer species (lifetime ∼6 ns). Quenching of the monomer excited state by CCl4 was studied and by comparison with phenol the singlet energy migration rate was established to be much less than 10−5 cm2 s−1. This is not surprising considering the short lifetime of the monomeric state (≲1 ns) and the ease of excimer formation. The fluorescence of films of PPZ showed a larger contribution from the monomeric state than would be expected by analogy to polystyrene.
Monte Carlo simulation for ultra-small MOS devices

Abstract This paper discusses advanced needs of Monte Carlo simulation approaches for MOS silicon devices scaled below 0.1 μ m channel length. For predictive simulation over a wide range of biases, it is necessary to provide the Monte Carlo procedure with tuning capabilities to adjust the mobility through calibration of the interface roughness scattering. This is accomplished by introducing a semi-empirical procedure with a physical elastic scattering rate and an inelastic rate with tunable strength. To resolve the role of hot carriers in relation to oxide interface damage, it is also important to realize fully bipolar MOS simulation, so that one can analyze the transport of impact-ionization generated carriers and secondary ionization. As the devices become quite small, three-dimensional simulation can be not only feasible, but also necessary to resolve the granularity of doping profiles and the complete carrier–carrier and carrier–ion interactions. Issues of device Monte Carlo implementation on parallel environments are discussed, and a practical approach for resolving the short-range forces of the charge–charge interaction in three dimensionals is described. Several examples and preliminary results are presented to illustrate the various issues.
UNCOVERING A SUPERNOVA REMNANT HIDDEN NEAR LMCX-1

In a kinematic study of LMC \hii\ regions, we serendipitously found a fast-expanding (velocity offsets up to ~200 \kms) shell in the northern lobe of the luminous \hii\ region N159. The expansion pattern and the \sii/\ha\ ratio of the shell are consistent with those seen in supernova remnants (SNRs). Confirmation of this SNR candidate in radio and X-ray wavelengths has been hampered by thermal emission of the luminous \hii\ region N159 itself and scattered X-rays from the nearby luminous source LMC X-1. Recent {ROSAT} observations finally resolved N159 from LMC X-1, thus confirming the identification of this as a newly identified SNR, which we designate as SNR 0540-697.
Structure of a DNA Polymerase α-Primase Domain That Docks on the SV40 Helicase and Activates the Viral Primosome

DNA polymerase α-primase (pol-prim) plays a central role in DNA replication in higher eukaryotes, initiating synthesis on both leading and lagging strand single-stranded DNA templates. Pol-prim consists of a primase heterodimer that synthesizes RNA primers, a DNA polymerase that extends them, and a fourth subunit, p68 (also termed B-subunit), that is thought to regulate the complex. Although significant knowledge about single-subunit primases of prokaryotes has accumulated, the functions and regulation of pol-prim remain poorly understood. In the SV40 replication model, the p68 subunit is required for primosome activity and binds directly to the hexameric viral helicase T antigen, suggesting a functional link between T antigen-p68 interaction and primosome activity. To explore this link, we first mapped the interacting regions of the two proteins and discovered a previously unrecognized N-terminal globular domain of p68 (p68N) that physically interacts with the T antigen helicase domain. NMR spectroscopy was used to determine the solution structure of p68N and map its interface with the T antigen helicase domain. Structure-guided mutagenesis of p68 residues in the interface diminished T antigen-p68 interaction, confirming the interaction site. SV40 primosome activity of corresponding pol-prim mutants decreased in proportion to the reduction in p68N-T antigen affinity, confirming that p68-T antigen interaction is vital for primosome function. A model is presented for how this interaction regulates SV40 primosome activity, and the implications of our findings are discussed in regard to the molecular mechanisms of eukaryotic DNA replication initiation.
Influence of task-related ipsilateral hand movement on motor cortex excitability.

Abstract Objective : The time course of the right motor cortex excitability in relation to a task-related voluntary right thumb twitch was studied using sub-threshold transcranial magnetic stimulation (TMS) to the right motor cortex. Methods : Motor excitability was studied in 8 adult subjects who made a brief right thumb twitch to the predictable omission of every fifth tone in a series of tones 2.5 s apart. This paradigm avoided an overt sensory cue, while allowing experimental control of TMS timing relative to both movement and the cue to move. Motor excitability was characterized by several measures of motor evoked potentials (MEPs) recorded from the left thenar eminence in response to TMS over the right scalp with a 9 cm coil: probability of eliciting MEPs, incidence of MEPs and amplitude of MEPs. Results : All subjects showed suppression of motor excitability immediately following a voluntary right thumb twitch (ipsilateral response), and up to 1 s after it. However, two distinctly different effects on motor excitability were observed before the response: two subjects showed excitation, beginning about 500 ms before response until 300 ms after it, followed by the post-movement suppression; 6 subjects displayed pre-movement suppression, beginning about 600 ms before the response and persisting for the duration. Conclusions : The net effect of an ipsilateral response on motor cortex can be either inhibitory or excitatory, changing with time relative to the response. These findings are compatible with two separate processes, inhibitory and excitatory, which interact to determine motor excitability ipsilateral to the responding hand.
Durable‐press cotton with improved retentions of strength and abrasion resistance via N‐methylolpolyethyleneurea D.P. 2

Diethylenetriamine was reacted with urea to form a noncyclic analog of ethyleneurea (one of the lowest members of a series of linear polyethyleneureas) which was characterized spectroscopically. Its reaction with formaldehyde to yield the N-methylol derivative (N-methylolpolyethyleneurea, degree of polymerization 2; NMP-2) was investigated. The polymerization characteristics of the NMP-2 were studied and compared with those of N-methylol derivatives of cyclic ethyleneurea (related structurally) and melamine (related polyfunctionally). The NMP-2 was applied to cotton fabrics by a pad–dry–cure process with Al2(OH)5Cl·2H2O as the polymerization crosslinking catalyst. Fabrics treated with the experimental reagent developed high levels of resilience (durable press appearance) and were characterized by significantly higher than conventional levels of retained strength and abrasion resistance. Analyses by electron microscopy of fibers treated with NMP-2 and with the predominant conventional reagent, dimethyloldihydroxyethyleneurea, are reported. Attractive performance properties are discussed and attributed, at least in part, to rapid polymerization accompanying, or in advance of, etherification of cellulosic hydroxyl groups.
Precipitation phenomenon in nanostructured Cr3C2-NiCr coatings

Abstract Precipitation in the nanostructured Cr3C2/NiCr coatings was investigated. Ultrafine Cr2O3 particles with an average size of 8.3 nm were observed using transmission electron microscopy in the nanostructured Cr3C2/NiCr coatings exposed to elevated temperatures. In addition to the precipitation of oxide particles, the phase transformations in the original NiCr amorphous phase, which was always observed in the as-sprayed nanostructured Cr3C2/NiCr coatings, were also identified. Internal oxidation was thought to be responsible for the precipitation of the dispersed oxide particles. The results of microhardness and scratch-resistance tests showed that microhardness of the conventional coating slightly increased only with an increase in the exposure temperature, while that of the nanostructured coating increased significantly from 1020 to 1240 HV300. Compared with the conventional Cr3C2/NiCr coatings, the scratch-resistance and coefficient of friction were found to be increased and reduced respectively in the nanostructured coatings. Heat treatment led to further increase in scratch-resistance and further decrease in coefficient of friction of the nanostructured coatings. The increases in microhardness and scratch-resistance and decrease in coefficient of friction of the nanostructured coatings were attributed to a high density of oxide nanoparticles precipitating within the coating as the exposure temperature increased.
Measuring Endocannabinoid Hydrolysis: Refining our Tools and Understanding

Endocannabinoids (eCBs) are lipid transmitters that are released from membrane precursors in response to specific stimuli, activate cannabinoid receptors—the molecular targets of compounds produced by Cannabis sativa—and are then rapidly inactivated by uptake and enzymatic hydrolysis. This signaling system is implicated in a wide range of biological processes, including pain sensation, immunomodulation, appetite regulation, development, and cognitive and emotional states. The balance between eCB release and inactivation determines the extent of eCB accumulation, with enzymatic hydrolysis functioning as an important limiting step. Pharmacological inhibition of eCB-hydrolyzing enzymes offers great therapeutic and experimental promise for enhancing this ubiquitous signaling system only where and when these transmitters are naturally produced. The following mini-review summarizes the latest developments concerning eCB-hydrolyzing enzymes, with an emphasis on the techniques used to measure their activities and how these have helped increase our understanding of the role that eCBs play in regulating fundamental biological functions.