bluuebunny/crossref_metadata_2025 huggingface dataset:
On-Line Birefringence Measurement in Film Blowing of a Linear Low Density Polyethylene
Authors: Ghaneh-Fard A. , Carreau P. J. , Lafleur P. G.
Published: December 2013

Blown film properties depend on the thermo-mechanical history experienced by molten polymer during biaxial deformation. In this study on-line birefringence measurements along the length of the bubble in film blowing of a linear low density polyethylene (LLDPE) were carried out in order to assess the stress level in the melt zone and total orientation in the solid zone. Bubble temperature measurements were carried out to find out the onset and the end of crystallization. Strain rates were also determined from bubble diameter and axial velocity measurements. We have focused on the effects of key processing parameters on the thermo-mechanical history of polymers. The relations between the birefringence and temperature profiles are described. The birefringence value is shown to be very small in the molten zone and increases rapidly as crystallization proceeds. The birefringence of the solidified film is strongly dominated by the crystalline phase contribution. Stresses in the molten blown film were calculated using the data of birefringence and pressure inside the bubble. The birefringence technique appears to be a promising but limited tool to determine stresses occurring in film blowing.
Brittle Melt Rupture Phenomena in Polymer Processing
Authors: Ghijsels A. , Massardier C. H. C. , Bradley R. M.
Published: December 2013

In this contribution the various rupture mechanisms which can occur during the elongation of polymer melts will be briefly reviewed, with the focus on the cohesive brittle melt rupture. Observations of melt rupture phenomena during polymer processing operations will be discussed. The occurrence of brittle melt rupture is characterised by a constant value of the rupture stress in the order of 1 MPa. Published rupture stress data on various polymer melts are critically discussed, in particular those on polyethylenes and other polyolefins. Using the Rheotens technique a newly developed method will be described to measure the melt rupture stress of polypropylene (PP) melts. The measurement of the rupture stress of PP melts is hampered by the occurrence of the instability draw resonance. This problem was overcome by applying more pronounced cooling conditions. Initial data on the rupture stress of PP melts will be presented. It is shown that the rupture stress of PP melts is not a constant but increases with increasing molecular weight.
An Experimental Study of Rotational Molding of Polypropylene/Polyethylene Copolymers
Authors: Kontopoulou M. , Bisaria M. , Vlachopoulos J.
Published: December 2013

The objectives of this work are to assess the rotomoldability of rubber toughened polypropylene resins and to investigate how resin properties can influence the process of rotational molding and the final part quality. Four commercially available polypropylene/polyethylene copolymers were tested. The chemical composition and the powder, rheological and thermal properties of the resins were determined. Rotational molding experiments were carried out in a laboratory scale uniaxial machine which is capable of measuring internal mold temperature and which facilitates the visual observation of various transitions in the cycle. Impact and environmental stress cracking resistance tests, as well as thickness distribution and density measurements were performed on the roto-molded parts. It was found that increasing rubber content results in an improvement of the impact properties which is counteracted by difficulties in processing, presence of bubbles and uneven surfaces.
Wide-Angle X-Ray, Densitometric and Microscopical Studies on Injection Molded Polypropylene Disks
Authors: Zipper P. , Jánosi A. , Wrentschur E. , Geymayer W. , Ingolic E. , Friesenbichler W. , Eigl F.
Published: December 2013

Circular disks (280 mm diameter, 2 mm thickness) were injection molded from two grades of isotactic polypropylene under systematic variation of processing parameters (melt temperature, mold temperature, flow rate, packing pressure, and packing time) according to a two-level fractional factorial design. The disks showed ring-shaped zones (“halos”) of enhanced turbidity. The wide-angle X-ray scattering of the disks was measured as a function of the distance from the gate at 13 positions along the radius, using a diffractometer and reflection geometry. These measurements yielded radial profiles of the orientation of α-PP and of the distribution of β-PP crystallites. Both kinds of profiles revealed clear correlations with the polymer grade and with the melt and/or mold temperature. Radial profiles of optical turbidity of the disks were obtained by means of a microdensitometer. Pronounced maxima of turbidity were found to coincide with the maxima observed in the radial distribution of β-PP. An analysis of variance (ANOVA) of the experiments showed that the mass temperature has the greatest influence on the radial distances of the maxima of turbidity. Increasing mass temperature led to decreasing radial distances of the turbidity maxima, whereas the mold temperature as well as the flow rate only had a small influence on the radial positions of the turbidity maxima. The investigation of cross-sections, which were taken from some disks at selected distances from gate, by means of optical microscopy using polarized light revealed significant changes in the morphology with increasing distance from gate, e.g., changes in the size and distribution of β-PP spherulites.
Shrinkage Prediction for Slowly-Crystallizing Thermoplastic Polymers in Injection Molding
Authors: Han S. , Wang K. K.
Published: December 2013

The prediction of shrinkage and warpage of crystalline polymers is quite difficult. This is because of the complications of the crystallization process and associated material property changes. In typical injection molding of semi-crystalline polymers, it is difficult to calculate crystallinity accurately because of its complicated dependence on temperature, time and stress. In the case of slowly-crystallizing polymers, typically the crystallinity of the polymer remains small during the process. In this case, therefore, the importance of accurate calculation of crystallinity is decreased. The difficulty in this case is the measurement of material properties under variable crystallinity because of the possible crystallization during measurement. In the present study, methods have been developed to obtain material properties which include the effect of crystallinity. The material properties measured include viscosity, thermal conductivity, heat capacity, PvT relation and crystallization kinetics.

Injection-molding experiments have been conducted to measure the shrinkage of a part using a slowly-crystallizing polymer. Shrinkage has been measured by comparing the mold cavity dimension and the dimension of the molded sample. The polymer used in this study is PET (polyethylene terephthalate).

A simulation program has been developed to analyze the injection-molding process. This program is based on quiescent crystallization kinetics. The predicted shrinkage and measured shrinkage are found to agree reasonably well.
The Optimized Quasi-Planar Approximation for Predicting Fiber Orientation in Injection-Molded Composites1
Authors: Ver Weyst B. E. , Tucker C. L. , Foss P. H.
Published: December 2013

Fiber filled injection-molded plastic parts contain complex fiber orientation patterns. This fiber orientation state affects material properties, including both elastic modulus and strength, and the calculation of shrinkage and warpage. Several models are available for predicting fiber orientation, which are based on the theory of Folgar and Tucker [1]. A particular simplification of these models, here called the quasi-planar (QP) approximation, was introduced by Gupta and Wang [2]. Here we develop a substantially improved version of that model, which we call the optimized quasi-planar (OQP) approximation. The OQP approximation is formed by optimizing the QP approximation against a more general fiber orientation model. Details of the current and improved models are discussed, and the typical behavior of the old and new models is explored. In addition, simulations are performed using C-MOLD, a commercial software package that implements the QP approximation, to determine the final fiber orientation state in an end-gated strip. The resulting fiber orientation data is then used to predict the elastic modulus as a function of position, and both predictions are compared to available experimental data for fiber orientation and elastic modulus. The results show that the OQP approximation improves the fiber orientation prediction and the subsequent elastic modulus prediction compared to the QP model, though the OQP approximation is still less accurate than the full three-dimensional model.
Physically-Based Adaptive Control of Cavity Pressure in Injection Molding: Filling Phase
Authors: Rafizadeh M. , Patterson W. I. , Kamal M. R.
Published: December 2013

Cavity pressure plays an important role in determining the quality of injection molded articles. The non-linear and time-varying nature of the process causes difficulties in implementing efficient control systems, which usually employ linear, time-invariant design strategies. Conversely, advanced control methods, such as self-tuning control, do not provide physical information about the process. A physically-based adaptive controller has been developed for cavity pressure control during the filling phase. Different control algorithms, employing different tuning criteria, were implemented on a microcomputer to control the cavity pressure. Experimental results indicate that this control yields accurate results for the injection molding of polyethylene. The results also show that this method, using the IMC algorithm, is superior to the classical optimal controller tuning approach.
In-Mould Shrinkage Measurements of PS Samples with Strain Gages
Authors: Pantani R. , Jansen K. M. B. , Titomanlio G.
Published: December 2013

The problem of shrinkage in injection moulding has been studied by means of a new technique based on strain gages placed on mould surface before injection. The local shrinkage development from the moment it starts inside the mould to soon after ejection can be followed by means of this method.

With reference to a simple rectangular cavity, the effects of different holding pressures, of geometrical constraints placed inside the mould, of position in the cavity and of total cavity length on local shrinkage of injected PS samples are analysed. Shrinkage inside the mould is, indeed, registered: it starts later if higher holding pressures are applied; furthermore, any factor which produces an enhancement of shrinkage evolution before complete solidification gives rise to a corresponding increase of final shrinkage.
Melt Flow Properties of LDPE/HDPE Blends in Capillary Extrusion
Authors: Liang J. Z. , Li R. K. Y. , Tjong S. C.
Published: December 2013

The melt flow properties of LDPE/HDPE blends in capillary extrusion have been investigated. It is found that the End pressure losses (ΔPend) increase as a form of non-linear function with increasing the wall shear stress (τw) and the ΔPend value of the sample is the minimum at the weight percentage content of HDPE (ΦHD) being 50% when the τw is fixed. The blend melt flow basically obeys the power law and the sensitivity of the melt viscosity (ηw) on the wall shear rate (γw) is weakened with increasing the ϕHD. Synergistic effect is obvious for the blend melts under experimental conditions. When the τw is 42.5KPa, the ηw value achieves the maximum at the ϕHD = 20%. In addition, the relationship between the ηw and the test temperature approximately accords with the Arrhenius equation as the τw is fixed.
Rheological Behaviour of LLDPE/LDPE Blends under Elongational Deformation
Authors: Micic P. , Bhattacharya S. N. , Field G.
Published: December 2013

The effect of temperature on the rheological response under elongation of two low density polyethylenes (LDPE 1 and LDPE 2), linear low density polyethylene (LLDPE) and their blends of different compositions was observed by using a constant strain rate elongational rheometer.

In addition, blends were tested in the oscillatory shear test, and the data measured at 160, 190, and 230°C indicate the larger level of intermolecular interactions in a blend than in the pure polymers.

Elongational viscosity measured at temperatures of 140, 150, 170 and 180°C revealed a much greater sensitivity for LLDPE (greater strain hardening with increasing temperature) to changing tenperature than is observed for LDPE.

This observatuion, coupled with the effect of melt morphology on elongational rheology, has been used to explain the synergism in elongational viscosity exhibited by LDP-E-rich blends.
Temperature Measuring in Plastics Processing with Infrared Radiation Thermometers
Authors: Obendrauf W. , Langecker G. R. , Friesenbichler W.
Published: December 2013

In many areas of plastics processing the temperature is a decisive process control parameter. Infrared sensors that detect the heat radiation from molten plastic have a response time in the range of milliseconds. Thus in many processes they offer the only possibility to measure time dependent temperatures with high accuracy.
Melt Grafting of Glycidyl Methacrylate onto Polyethylene
Authors: Hojabr S. , Baker W. E. , Russell K. E. , McLellan P. J. , Huneault M. A.
Published: December 2013

The melt grafting of Glycidyl Methacrylate (GMA) onto Polyethylene in the presence of free radical initiators was conducted in a co-rotating twin screw extruder. Reaction kinetic parameters for the overall grafting and homopolymerization reactions were estimated in a batch melt mixer. Residence time distribution (RTD) in the extruder was determined and mean residence time and Peclet number (Pe) were estimated for different sets of reaction conditions.

A twin screw simulation program was used to predict the flow characteristics along the length of the extruder. A modular reactor model consisting of plug flow and “axial dispersion” reactor cells was constructed and with the kinetic and transport information and the actual melt temperatures, the overall GMA conversion was predicted. In most cases the predicted conversion agreed well with experimentally determined values.
Sensitivity of In-line Rheometry for Extrusion of Mg(OH)2 filled LDPE Compounds
Authors: Coates P. D. , Rose R. M. , Woodhead M. , Kelly A. L.
Published: December 2013

In-process and off-line rheometry studies are reported for compounds based on Mg(OH)2 filled low density polyethylene, some of which were first subjected to a range of strain histories in typical compounding operations. In the study reported here, the compounds were processed using an instrumented, computer monitored single screw extruder in the IRC laboratories, fitted with in line rheometers (ILR). In initial experiments a four sensor ILR slit die was used for the in-process shear rheometry, and a Rosand RH7 twin bore capillary rheometer for off-line shear and entry pressure measurements. Off line and in-line results are compared, showing good agreement for shear. Estimates have been obtained for the sensitivity to filler loading of the off line rheometer (shear flow and entry pressure measurements), and the 4 sensor ILR (shear flow measurements), which indicate that the ILR offers similar resolution of filler level to the off line rheometer at the higher loadings, although the ILR appears to have much lower sensitivity at higher shear rates at lower loadings, an effect which appears to be related to processing effects on the rheology of the compound rather than the measurement ability of the ILR. The ILR was also able to discriminate between samples with differing processing histories. Results from a six-sensor ILR die have shown good agreement in shear flow measurements, and have added the ability to measure entry pressures, which are compared with off-line measurements.
Finite Element Analysis of Mixing in Partially Filled Twin Blade Internal Mixers
Authors: Nassehi V. , Ghoreishy M. H. R.
Published: December 2013

Twin blade internal mixers are the main devices used in rubber processing industry to mix natural and synthetic rubbers with carbon black and other compounding ingredients. To facilitate mixing, these internal mixers are always partially filled. Consequently, the flow regime that becomes established inside the mixer is a multiple random free surface flow with moving external boundaries. The stress field associated with this flow regime is usually very uneven. In addition, the flow stream is continuously divided and rejoined by the action of the counter rotating blades. The combination of these complex effects results in the break down, dispersion and distribution of carbon black agglomerates within the rubber matrix. The efficiency of the entire process mainly depends on the geometry of the mixer blades and the operating conditions. Predictive computer modelling offers a very convenient method for the quantitative analysis of mixing process and can be used to design more efficient internal mixers. However, the successful modelling of a complex process such as rubber mixing requires the development and use of sophisticated mathematical algorithms that can take into account its main characteristics. In this respect, a major difficulty is the imposition of the transient boundary conditions in a continuously varying flow domain. In the present paper we describe a robust method which can very effectively resolve this problem. This method is based on the combination of Lagrangian and Eulerian approaches for the modelling of moving boundary flows. We have used this scheme to simulate flow and mixing in the cross-sectional plane of the blades of a tangential rotor internal mixer.
Use of Dye Containing Polymeric Microcapsules for Determining Shear Stresses
Authors: Clark D. C. , Baker W. E. , Condo A. C. , Kosowski B. M.
Published: December 2013

This paper evaluates a method of measuring shear stress, in-situ, in polymer flows. The rupture response of two different dye containing polymeric microcapsules, CM511 and CM567, is examined in both an internal batch mixer and a lab scale single screw extruder (SSE), using ultraviolet/visible spectrophotometry (UV/VIS), colorimetric analysis (CA) and optical microscopy (OM). It is observed that both particles rupture over a wide range of shear stresses and times. In particular, both CM511 and CM567 begin to rupture at ∼ 100 kPa, while complete rupture is only detected for the CM567 at average stress levels greater than or equal to ∼ 230 kPa. Complete rupture for the CM511 is not observed over the average shear stress range investigated. The microcapsules further indicate the change in the melting mechanism in a SSE when the processing conditions are changed.
Impregnating Flow of a Rheokinetic Liquid
Authors: Malkin A. Ya. , Kuznetsov V. V.
Published: December 2013

A problem of penetration of a viscous liquid into a porous medium with simultaneous squeezing along the surface of this medium is formulated and discussed. The movement of a liquid is initiated by compressing a viscous drop positioned between the upper plate and the porous medium. The system of equations determining the changing of pressure and evolution of an impregnation front was formulated and discussed in dimensionless variables. Typical solutions were obtained for different sets of characteristic parameters including the case of an anisotropic porous medium. Varying the determining parameters leads to different relationships between impregnation and surface squeezing.

It was proven that the formulation of the problem under discussion and solutions obtained in dimensionless form are valid for a “rheokinetic” liquid (viscosity changing due to chemical reactions during flow), if an isothermal situation is considered. However flow of a rheokinetic liquid ceases due to unlimited growth of its viscosity and necessity to increase pressure if we want to maintain the preset velocity of the upper pressing plate.
Utilization of Recycled Crumb Rubber as a Compounding Tool
Authors: Kim J. K.
Published: December 2013

The disposal of used automobile tires has become a major environmental problem, and although there are obvious environmental reasons for recycling waste tires, to date it has not taken place because it is not cost-effective.

The aim of this study was to find a more effective method of recycling used automobile tires. This was done by comparing the methods of using vulcanized crumb rubber as a filler, and investigation of the effect of surface treatment with microscopic examination of the fracture morphology of the filled crumb rubber elastomers.

The experimental results indicate that crumb rubber filler end-product properties were enhanced by the chlorination of crumb rubber, and by developing a crumb rubber incorporation method. We found that much improvement of the mechanical performance of the crumb rubber filled elastomer compounds could be achieved by developing a better crumb rubber incorporation technique.
Modeling of Segmented Polyurethane Drying Process
Authors: Abraham G. A. , Cuadrado T. R.
Published: December 2013

Biomedical segmented polyurethanes (SPU) are frequently processed by solution-casting techniques in order to obtain multilayerfilms. For processing parameters setup empirical criteria is currently applied. However, the selected conditions can strongly affect the physico-chemical properties of the finished articles and they must be accurately established. In order to describe the SPU coating formation, balances of heat, mass and momentum transfer must be considered.

To study the drying process, two new medical-grade SPU solutions commercially available, BiospanTM and Chronoflex ARTM, were dried at different temperatures. Desorption curves and drying rate, both as a function of temperature, were obtained from experimental data. The mathematical model to describe this process take into account the heat and mass transfer and film shrinkage along the whole drying step. The diffusion coefficients and the control mechanism were determined from the best experimental data fitting.

To obtain the solvent concentration profile, residual solvent and film, thickness at any time, heat and mass transfer balances were numerically solved using an explicit finite-difference method. The formulations showed different behavior. For Biospan drying, performed in the range from 5°C to 8°C, a two-stage process was observed. The first one controlled by mass transfer in the gas phase and the second one with mix control. When 4°C drying temperature was applied, a mix control was found along the whole process. This change could be attributed to the acrylic additive present in the SPU matrix, which has a glass transition temperature value in the range of the process temperature. Chronoflex samples showed a two-stage process in all cases and lower diffusion coefficients than Biospan samples.
Simulation of Reactive Liquid Composite Molding
Authors: Wu C.-H. , Chiu H.-T. , Lee L. J. , Nakamura S.
Published: December 2013

The control-volume finite element method (CVFEM) has been used widely to simulate the mold filling process in polymer processing because it is more user friendly and more robust than the conventional finite element or finite difference methods. However, using lower order interpolation functions in CVFEM may result in significant numerical errors. This is especially true for convection–diffusion problems with a changeable source term as in reactive liquid composite molding (LCM). In this study, an Eulerian–Lagrangian approach is proposed where an Eulerian coordinate system is used to solve the velocity field, while the chemical species balance and the energy balance are based on a Lagrangian coordinate system. This approach is used to simulate the non-isothermal LCM process.
Structure and Properties of Injection Moldings of β-Crystal Nucleator-added PP
Authors: Fujiyama M.
Published: December 2013

Aiming at a synergism of improvements of impact strength of polypropylene by the addition of β-crystal nucleator and of its rigidity by the filling of particulate, the addition of the nucleator to particulate-filled polypropylenes has been studied. 0 to 3000 ppm of γ-quinacridone (GQ) which is a β-crystal nucleator was added to homo isotactic polypropylenes (PP) filled with 0 to 30 wt-% of talc (TC) which shows an α-crystal nucleating effect, of mica (MC), or of glass flake (GF), last two of which show β-crystal nucleating effects. Flexural and Izod impact test specimens were injection-molded from the PPs under constant molding conditions and the structure and properties have been investigated. The β-crystal content is reduced by the filling of particulates. The degree of the reduction is in the order of TC >MC >GF, which agrees with that of the crystallization temperature. The flexural modulus decreases slightly with increasing GQ content and increases with increases in particulate contents. The increase is in the order of MC > TC > GF, which agrees with that of the aspect ratio. The enhancing effect of the Izod impact strength by the addition of GQ decreases with increasing particulate contents and diminishes at contents above 10 wt-%. Particulates deteriorate the enhanced impact strength of β-PP. Thus the expected synergism could not be obtained enough.
Using Unmanned Aerial Vehicles (UAV) for High-Resolution Reconstruction of Topography: The Structure from Motion Approach on Coastal Environments
Authors: Mancini Francesco , Dubbini Marco , Gattelli Mario , Stecchi Francesco , Fabbri Stefano , Gabbianelli Giovanni
Published: December 2013

The availability of high-resolution Digital Surface Models of coastal environments is of increasing interest for scientists involved in the study of the coastal system processes. Among the range of terrestrial and aerial methods available to produce such a dataset, this study tests the utility of the Structure from Motion (SfM) approach to low-altitude aerial imageries collected by Unmanned Aerial Vehicle (UAV). The SfM image-based approach was selected whilst searching for a rapid, inexpensive, and highly automated method, able to produce 3D information from unstructured aerial images. In particular, it was used to generate a dense point cloud and successively a high-resolution Digital Surface Models (DSM) of a beach dune system in Marina di Ravenna (Italy). The quality of the elevation dataset produced by the UAV-SfM was initially evaluated by comparison with point cloud generated by a Terrestrial Laser Scanning (TLS) surveys. Such a comparison served to highlight an average difference in the vertical values of 0.05 m (RMS = 0.19 m). However, although the points cloud comparison is the best approach to investigate the absolute or relative correspondence between UAV and TLS methods, the assessment of geomorphic features is usually based on multi-temporal surfaces analysis, where an interpolation process is required. DSMs were therefore generated from UAV and TLS points clouds and vertical absolute accuracies assessed by comparison with a Global Navigation Satellite System (GNSS) survey. The vertical comparison of UAV and TLS DSMs with respect to GNSS measurements pointed out an average distance at cm-level (RMS = 0.011 m). The successive point by point direct comparison between UAV and TLS elevations show a very small average distance, 0.015 m, with RMS = 0.220 m. Larger values are encountered in areas where sudden changes in topography are present. The UAV-based approach was demonstrated to be a straightforward one and accuracy of the vertical dataset was comparable with results obtained by TLS technology.
Fault Diagnosis of Rotating Machinery Based on an Adaptive Ensemble Empirical Mode Decomposition
Authors: Lei Yaguo , Li Naipeng , Lin Jing , Wang Sizhe
Published: December 2013

The vibration based signal processing technique is one of the principal tools for diagnosing faults of rotating machinery. Empirical mode decomposition (EMD), as a time-frequency analysis technique, has been widely used to process vibration signals of rotating machinery. But it has the shortcoming of mode mixing in decomposing signals. To overcome this shortcoming, ensemble empirical mode decomposition (EEMD) was proposed accordingly. EEMD is able to reduce the mode mixing to some extent. The performance of EEMD, however, depends on the parameters adopted in the EEMD algorithms. In most of the studies on EEMD, the parameters were selected artificially and subjectively. To solve the problem, a new adaptive ensemble empirical mode decomposition method is proposed in this paper. In the method, the sifting number is adaptively selected, and the amplitude of the added noise changes with the signal frequency components during the decomposition process. The simulation, the experimental and the application results demonstrate that the adaptive EEMD provides the improved results compared with the original EEMD in diagnosing rotating machinery.
A method for extracting high‐quality RNA from diverse plants for next‐generation sequencing and gene expression analyses
Authors: Yockteng Roxana , Almeida Ana M. R. , Yee Stephen , Andre Thiago , Hill Colin , Specht Chelsea D.
Published: December 2013

• Premise of the study: To study gene expression in plants, high‐quality RNA must be extracted in quantities sufficient for subsequent cDNA library construction. Field‐based collections are often limited in quantity and quality of tissue and are typically preserved in RNAlater. Obtaining sufficient and high‐quality yield from variously preserved samples is essential to studies of comparative biology. We present a protocol for the extraction of high‐quality RNA from even the most recalcitrant plant tissues.

• Methods and Results: Tissues from mosses, cycads, and angiosperm floral organs and leaves were preserved in RNAlater or frozen fresh at −80°C. Extractions were performed and quality was measured for yield and purity.

• Conclusions: This protocol results in the extraction of high‐quality RNA from a variety of plant tissues representing vascular and nonvascular plants. RNA was used for cDNA synthesis to generate libraries for next‐generation sequencing and for expression studies using quantitative PCR (qPCR) and semiquantitative reverse transcription PCR (RT‐PCR).
Geo-mapping Frontiers: predictive geology map of the Ennadai region, Nunavut
Authors: Hayward N , Harris J R , Grunsky E , Beauchemin M , Jefferson C , Peterson T
Published: December 2013

In the final phase of the Geomapping for Energy and Minerals (GEM) Program, a project entitled Geo-mapping Frontiers ( http://www.nrcan.gc.ca/earth-sciences/about/current-program/geomapping/minerals/11975 ) was initiated to improve geoscience knowledge in the
least understood parts of Canada's north. An inventory was first conducted to evaluate the state of knowledge in parts of Nunavut, NWT and Yukon shown as having insufficient knowledge to support decision-making. Criteria included: 1) mapped at 250K scale or coarser; 2) mapped prior to aeromagnetic
coverage; 3) lacking modern U-Pb age information on major units; 4) lacking Nd-Sm model age data; 5) lacking thermochronological data; 6) lacking a stratigraphic framework for supracrustal rocks; 7) lacking subdivision of granitic rocks; and 8) mineral potential unconfirmed. Eleven areas identified
during a preliminary scan were discussed with territorial geological surveys in the spirit of the Intergovernmental Geoscience Accord. In light of the consultation process, four geographic areas were prioritized for investigation from a minerals perspective (Chantrey, Ennadai, South Rae and Tehery
transects), and two topics were selected for Energy research.
The project is consolidating and improving existing information (data mining, compilation and remote predictive mapping), acquiring new data (e.g. geophysical, geochemical surveys), testing emerging models through targeted field work, contributing to completion of the Tri-territorial database, and
advancing planning with regard to future work. Activities are also aimed at stimulating direct industry interest through timely delivery of maps, reports, compilations and datasets.
The data in this Open File include data compilation and re-interpretation of the geology using Remote Predictive Mapping (RPM) techniques for the Ennadai region shown in Figure 1. This region was selected as one of the areas requiring improved mapping as part of the GEM Geo-Frontiers mapping
project.
PIMA Point of Care CD4+ Cell Count Machines in Remote MNCH Settings: Lessons Learned from Seven Districts in Zimbabwe
Authors: Mtapuri-Zinyowera Sekesai , Chiyaka Edward T. , Mushayi Wellington , Musuka Godfrey , Naluyinda-Kitabire Florence , Mushavi Angella , Chikwasha Vasco
Published: December 2013

An evaluation was commissioned to generate evidence on the impact of PIMA point-of-care CD4+ count machines in maternal and new-born child health settings in Zimbabwe; document best practices, lessons learned, challenges, and recommendations related to scale up of this new technology. A mixed methodology approach that included 31 in-depth interviews with stakeholders involved in procurement, distribution, and use of the POC machines was employed. Additionally, data was also abstracted from 207 patient records from 35 sites with the PIMA POC CD4+ count machines and 10 other comparative sites without the machine. A clearer training strategy was found to be necessary. The average time taken to initiate clients on antiretroviral treatment (ART) was substantially less, 15 days (IQR-1-149) for sites with a PIMA POC machine as compared to 32.7 days (IQR-1-192) at sites with no PIMA POC machine. There was general satisfaction because of the presence of the PIMA POC CD4+ count machine at sites that also initiated ART.
The Immune System as Drug Target
Authors: Flower Darren R.
Published: December 2013

The immune system is perhaps the largest yet most diffuse and distributed somatic system in vertebrates. It plays vital roles in fighting infection and in the homeostatic control of chronic disease. As such, the immune system in both pathological and healthy states is a prime target for therapeutic interventions by drugs–-both small-molecule and biologic. Comprising both the innate and adaptive immune systems, human immunity is awash with potential unexploited molecular targets. Key examples include the pattern recognition receptors of the innate immune system and the major histocompatibility complex of the adaptive immune system. Moreover, the immune system is also the source of many current and, hopefully, future drugs, of which the prime example is the monoclonal antibody, the most exciting and profitable type of present-day drug moiety. This brief review explores the identity and synergies of the hierarchy of drug targets represented by the human immune system, with particular emphasis on the emerging paradigm of systems pharmacology.
On the Theorem of the Primitive Element with Applications to the Representation Theory of Associative and Lie Algebras
Authors: Cagliero Leandro , Szechtman Fernando
Published: December 2013

We describe all finite dimensional uniserial representations of a commutative associative (resp. abelian Lie) algebra over a perfect (resp. sufficiently large perfect) field. In the Lie case the size of the field depends on the answer to following question, considered and solved in this paper. LetK/Fbe a finite separable field extension and letx, y∊K. When isF[x,y] =F[αx + βy] for some nonzero elementsα, β∊F?
Invited review: Graphite and its hidden superconductivity
Authors: Esquinazi Pablo
Published: December 2013

We review experimental results, from transport to magnetization measurements, on different graphite samples, from bulk oriented graphite, thin graphite films to transmission electron microscope lamellae, that indicate the existence of granular superconductivity at temperatures above 100~K. The   accumulated evidence speaks for a localization of the superconducting phase(s) at certain interfaces  embedded in semiconducting crystalline regions with Bernal stacking order.Received: 25 January 2013, Accepted: 10 October 2013; Reviewed by: E. M. Forgan, School of Physics & Astronomy, University of Birmingham, U.K.; Edited by: S. A. Grigera; DOI: http://dx.doi.org/10.4279/PIP.050007Cite as: P Esquinazi, Papers in Physics 5, 050007 (2013)
Midlatitude cirrus classification at Rome Tor Vergata through a multichannel Raman–Mie–Rayleigh lidar
Authors: Dionisi D. , Keckhut P. , Liberti G. L. , Cardillo F. , Congeduti F.
Published: December 2013

Abstract. A methodology to identify and characterize cirrus clouds has been developed and applied to the multichannel-multiwavelength Rayleigh–Mie–Raman (RMR) lidar in Rome Tor Vergata (RTV). A set of 167 cirrus cases, defined on the basis of quasi-stationary temporal period conditions, has been selected in a data set consisting of about 500 h of nighttime lidar sessions acquired between February 2007 and April 2010. The derived lidar parameters (effective height, geometrical and optical thickness and mean back-scattering ratio) and the cirrus mid-height temperature (estimated from the radiosonde data of Pratica di Mare, WMO, World Meteorological Organization, site no. 16245) of this sample have been analyzed by the means of a clustering multivariate analysis. This approach identified four cirrus classes above the RTV site: two thin cirrus clusters in mid- and upper troposphere and two thick cirrus clusters in mid-upper troposphere. These results, which are very similar to those derived through the same approach at the lidar site of the Observatoire de Haute-Provence (OHP), allows characterization of cirrus clouds over the RTV site and attests to the robustness of such classification. To acquire some indications about the cirrus generation methods for the different classes, analyses of the extinction-to-backscatter ratio (lidar ratio, LReff, in terms of frequency distribution functions and dependencies on the mid-height cirrus temperature, have been performed. A preliminary study relating some meteorological parameters (e.g., relative humidity, wind components) to cirrus clusters has also been conducted. The RTV cirrus results, recomputed through the cirrus classification by Sassen and Cho (1992), show good agreement with other midlatitude lidar cirrus observations for the relative occurrence of subvisible (SVC), thin and opaque cirrus classes (10%, 49% and 41%, respectively). The overall mean value of cirrus optical depth is 0.37 ± 0.18, while most retrieved LReff values range between 10–60 sr, and the estimated mean value is 31 ± 15 sr, similar to LR values of lower latitude cirrus measurements. The obtained results are consistent with previous studies conducted with different systems and confirm that cirrus classification based on a statistical approach seems to be a good tool both to validate the height-resolved cirrus fields calculated by models and to investigate the key processes governing cirrus formation and evolution. However, the lidar ratio and optical depth analyses are affected by some uncertainties (e.g., lidar error noise, multiple scattering effects, supercooled water clouds) that reduce the confidence of the results. Future studies are needed to improve the characterization of the cirrus optical properties and, thus, the determination of their radiative impact.
The contribution of oceanic methyl iodide to stratospheric iodine
Authors: Tegtmeier S. , Krüger K. , Quack B. , Atlas E. , Blake D. R. , Boenisch H. , Engel A. , Hepach H. , Hossaini R. , Navarro M. A. , Raimund S. , Sala S. , Shi Q. , Ziska F.
Published: December 2013

Abstract. We investigate the contribution of oceanic methyl iodide (CH3I) to the stratospheric iodine budget. Based on CH3I measurements from three tropical ship campaigns and the Lagrangian transport model FLEXPART, we provide a detailed analysis of CH3I transport from the ocean surface to the cold point in the upper tropical tropopause layer (TTL). While average oceanic emissions differ by less than 50% from campaign to campaign, the measurements show much stronger variations within each campaign. A positive correlation between the oceanic CH3I emissions and the efficiency of CH3I troposphere–stratosphere transport has been identified for some cruise sections. The mechanism of strong horizontal surface winds triggering large emissions on the one hand and being associated with tropical convective systems, such as developing typhoons, on the other hand, could explain the identified correlations. As a result of the simultaneous occurrence of large CH3I emissions and strong vertical uplift, localized maximum mixing ratios of 0.6 ppt CH3I at the cold point have been determined for observed peak emissions during the SHIVA (Stratospheric Ozone: Halogen Impacts in a Varying Atmosphere)-Sonne research vessel campaign in the coastal western Pacific. The other two campaigns give considerably smaller maxima of 0.1 ppt CH3I in the open western Pacific and 0.03 ppt in the coastal eastern Atlantic. In order to assess the representativeness of the large local mixing ratios, we use climatological emission scenarios to derive global upper air estimates of CH3I abundances. The model results are compared with available upper air measurements, including data from the recent ATTREX and HIPPO2 aircraft campaigns. In the eastern Pacific region, the location of the available measurement campaigns in the upper TTL, the comparisons give a good agreement, indicating that around 0.01 to 0.02 ppt of CH3I enter the stratosphere. However, other tropical regions that are subject to stronger convective activity show larger CH3I entrainment, e.g., 0.08 ppt in the western Pacific. Overall our model results give a tropical contribution of 0.04 ppt CH3I to the stratospheric iodine budget. The strong variations in the geographical distribution of CH3I entrainment suggest that currently available upper air measurements are not representative of global estimates and further campaigns will be necessary in order to better understand the CH3I contribution to stratospheric iodine.
The metastable HCl · 6H2O phase – IR spectroscopy, phase transitions and kinetic/thermodynamic properties in the range 170–205 K
Authors: Chiesa S. , Rossi M. J.
Published: December 2013

Abstract. In this laboratory study a multidiagnostic experimental approach including Fourier transform infrared (FTIR) absorption of 1 to 2 μm thick polycrystalline ice films, residual gas mass spectrometry (MS) and total pressure measurement were employed. Both amorphous HCl–H2O and crystalline HCl hexahydrate (HCl · 6H2O) have been investigated. After controlled doping with HCl and evaporation of excess H2O from the ice film, transmission FTIR of pure HCl · 6H2O films and use of calibrated mass spectrometry enabled the measurement of differential (peak) IR cross sections at several mid-IR frequencies, for example σ = (6.5 ± 1.9) × 10−19 cm2 molec−1 at 1635 cm−1. Two types of kinetic experiments on pure HCl · 6H2O have been performed under SFR conditions: (a) evaporation of pure HCl · 6H2O over a narrow T range after evaporation of excess H2O, and (b) observation of the phase transition from crystalline HCl · 6H2O to amorphous HCl–H2O under H2O-rich conditions at increasing T. The temperature dependence of the zero-order evaporation flux of HCl in pure HCl · 6H2O led to logJev molec cm−2 s−1 = (36.34 ± 3.20) – (80 810 ± 5800)/2.303 RT with R = 8.314 JK−1 mol−1, which turned out to be rate-limiting for evaporation. HCl · 6H2O has a significant intrinsic kinetic barrier to HCl evaporation of 15.1 kJ mol−1 in excess of the HCl sublimation enthalpy of 65.8 kJ mol−1 at 200 K but is kinetically unstable (metastable) at T ≥ 173 K. The atmospheric importance of HCl · 6H2O is questioned in view of its large nucleation barrier and its dependence on T and P(HCl) compared to the amorphous HCl–H2O phase at upper tropospheric–lower stratospheric (UT/LS) conditions.
Radiative consequences of low-temperature infrared refractive indices for supercooled water clouds
Authors: Rowe P. M. , Neshyba S. , Walden V. P.
Published: December 2013

Abstract. Simulations of cloud radiative properties for climate modeling and remote sensing rely on accurate knowledge of the complex refractive index (CRI) of water. Although conventional algorithms employ a temperature-independent assumption (TIA), recent infrared measurements of supercooled water have demonstrated that the CRI becomes increasingly ice-like at lower temperatures. Here, we assess biases that result from ignoring this temperature dependence. We show that TIA-based cloud retrievals introduce spurious ice into pure, supercooled clouds, or underestimate cloud optical thickness and droplet size. TIA-based downwelling radiative fluxes are lower than those for the temperature-dependent CRI by as much as 1.7 W m−2 (in cold regions), while top-of-atmosphere fluxes are higher by as much as 3.4 W m−2 (in warm regions). Proper accounting of the temperature dependence of the CRI, therefore, leads to significantly greater local greenhouse warming due to supercooled clouds than previously predicted. The current experimental uncertainty in the CRI at low temperatures must be reduced to account for supercooled clouds properly in both climate models and cloud-property retrievals.
Reactive uptake of N2O5 to internally mixed inorganic and organic particles: the role of organic carbon oxidation state and inferred organic phase separations
Authors: Gaston C. J. , Thornton J. A. , Ng N. L.
Published: December 2013

Abstract. We measured N2O5 reactive uptake onto mixed organic/inorganic submicron particles using organic compounds with a variety of oxidation states (using mainly atomic O : C ratios as a proxy) and molecular weights. The organic mass fraction, organic molecular composition, and relative humidity (RH) were varied to separately assess their effect on the N2O5 uptake coefficient, γ(N2O5). At a constant RH, mixtures of organic components having an O : C < 0.5 with ammonium bisulfate (ABS) significantly suppressed the uptake of N2O 0.8) had a smaller or even negligible impact on N2O5 uptake at all RHs probed; however, a few exceptions were observed. Notably, γ(N2O5) for mixtures of ABS with polyethylene glycol (PEG), PEG-300 (O : C = 0.56), decreased nearly linearly as the PEG mass fraction increased at constant RH until leveling off at the value measured on pure PEG. The response of γ(N2O5) to increasing PEG mass fraction was similar to that measured on ambient atmospheric particles as a function of organic mass fraction. The effects of the organic mass fraction on γ(N2O5), for mixtures having an O : C < ~ 0.8, were best described using a standard resistor model of reactive uptake assuming the particles had a RH dependent inorganic core-organic shell morphology. This model suggests that the N2O5 diffusivity and/or solubility in the organic layer is up to a factor of 20 lower compared to aqueous solution particles, and that the diffusivity, solubility, and reactivity of N2O5 within organic coatings and particles depend upon both RH and the molecular composition of the organic medium. We use these dependencies and ambient measurements of organic aerosol from the global aerosol mass spectrometry (AMS) database to show that the typical impact of organic aerosol components is to both uniformly decrease γ(N2O5), by up to an order of magnitude depending on the RH, organic mass fraction, and O : C ratio, and to induce a stronger dependence of γ(N2O5) upon RH compared to purely inorganic aqueous solutions.