Heat transfer through porous multiphase systems: measurement, modelling and application in printing of coated papers

This work examines the thermal transfer through porous media by means of measurement of the effective thermal conductivity and modelling of the structural parameters. While most of the work is of a general nature, the porous media in focus are pigment plus latex binder systems as used for paper coatings. As such, the application field of thermal effects in printing is discussed. At first the use of a dynamic measurement method for the thermal conductivity of porous coating pigment binder systems in the form of tablets is evaluated. In addition, a Lumped Parameter Model is developed to analyse the measured thermal conductivities in terms of the material volume fractions and their structural configuration. The model therefore uses two independent structural parameters instead of porosity alone as the governing parameter. This enables a discussion following modelling approaches adopting parameter modelling and structural modelling. A combination of both is used to discuss the solid-solid connectivity of pigment binder systems. It is shown by the model parameter of pigment connectivity that a disruption of the pigment packing already at low concentrations of binder occurs related to surface and colloid chemistry factors which cause the binder to accumulate first at pigment nodal points. The analysis of different pigment binder systems shows that, due to the presence of two interacting solid phases, the effective thermal conductivity cannot be modelled by using porosity and pore structure alone, but also requires the additional parameter of dual solid phase connectivity. It is proposed, therefore, that a combination of pore structure analysis and thermal conductivity measurement can be used to identify and parameterise subtleties in interactive particulate systems. For the application of toner fusing in electrophotography it is shown that a thermally insulating coating layer leads to a concentration of the fusing energy on the surface, thus aiding the fusing/adhesion development of the toner while shielding the base paper from undesired heating. In the heatset web-offset drying process, an insulating precoating in combination with liquid barrier properties can lead to a similar shielding of the base paper and thus helps to maintain an even moisture profile effectively reducing the waving/fluting tendency

Self-assembly of gold nanoparticles at the oil-vapor interface: from mono- to multilayers

Alkylthiol-coated gold nanoparticles spontaneously segregate from dispersion in toluene to the toluene-vapor interface. We show that surface tension drops during segregation with a rate that depends on particle concentration. Mono- and multilayers of particles form depending on particle concentration, time, and temperature. X-ray reflectometry indicates fast monolayer formation and slow multilayer formation. A model that combines diffusion-limited segregation driven by surface energy and heterogeneous agglomeration driven by dispersive van der Waals particle interactions is proposed to describe film formation

Integrating Hebbian and homeostatic plasticity: the current state of the field and future research directions

We summarize here the results presented and subsequent discussion from the meeting on Integrating Hebbian and Homeostatic Plasticity at the Royal Society in April 2016. We first outline the major themes and results presented at the meeting. We next provide a synopsis of the outstanding questions that emerged from the discussion at the end of the meeting and finally suggest potential directions of research that we believe are most promising to develop an understanding of how these two forms of plasticity interact to facilitate functional changes in the brain.This article is part of the themed issue 'Integrating Hebbian and homeostatic plasticity'

Antiangiogenic agents in the treatment of recurrent or newly diagnosed glioblastoma: Analysis of single-agent and combined modality approaches

Surgical resection followed by radiotherapy and temozolomide in newly diagnosed glioblastoma can prolong survival, but it is not curative. For patients with disease progression after frontline therapy, there is no standard of care, although further surgery, chemotherapy, and radiotherapy may be used. Antiangiogenic therapies may be appropriate for treating glioblastomas because angiogenesis is critical to tumor growth. In a large, noncomparative phase II trial, bevacizumab was evaluated alone and with irinotecan in patients with recurrent glioblastoma; combination treatment was associated with an estimated 6-month progression-free survival (PFS) rate of 50.3%, a median overall survival of 8.9 months, and a response rate of 37.8%. Single-agent bevacizumab also exceeded the predetermined threshold of activity for salvage chemotherapy (6-month PFS rate, 15%), achieving a 6-month PFS rate of 42.6% (p < 0.0001). On the basis of these results and those from another phase II trial, the US Food and Drug Administration granted accelerated approval of single-agent bevacizumab for the treatment of glioblastoma that has progressed following prior therapy. Potential antiangiogenic agents-such as cilengitide and XL184-also show evidence of single-agent activity in recurrent glioblastoma. Moreover, the use of antiangiogenic agents with radiation at disease progression may improve the therapeutic ratio of single-modality approaches. Overall, these agents appear to be well tolerated, with adverse event profiles similar to those reported in studies of other solid tumors. Further research is needed to determine the role of antiangiogenic therapy in frontline treatment and to identify the optimal schedule and partnering agents for use in combination therapy

Large-Scale simulations of plastic neural networks on neuromorphic hardware

SpiNNaker is a digital, neuromorphic architecture designed for simulating large-scale spiking neural networks at speeds close to biological real-time. Rather than using bespoke analog or digital hardware, the basic computational unit of a SpiNNaker system is a general-purpose ARM processor, allowing it to be programmed to simulate a wide variety of neuron and synapse models. This flexibility is particularly valuable in the study of biological plasticity phenomena. A recently proposed learning rule based on the Bayesian Confidence Propagation Neural Network (BCPNN) paradigm offers a generic framework for modeling the interaction of different plasticity mechanisms using spiking neurons. However, it can be computationally expensive to simulate large networks with BCPNN learning since it requires multiple state variables for each synapse, each of which needs to be updated every simulation time-step. We discuss the trade-offs in efficiency and accuracy involved in developing an event-based BCPNN implementation for SpiNNaker based on an analytical solution to the BCPNN equations, and detail the steps taken to fit this within the limited computational and memory resources of the SpiNNaker architecture. We demonstrate this learning rule by learning temporal sequences of neural activity within a recurrent attractor network which we simulate at scales of up to 2.0 × 104 neurons and 5.1 × 107 plastic synapses: the largest plastic neural network ever to be simulated on neuromorphic hardware. We also run a comparable simulation on a Cray XC-30 supercomputer system and find that, if it is to match the run-time of our SpiNNaker simulation, the super computer system uses approximately 45× more power. This suggests that cheaper, more power efficient neuromorphic systems are becoming useful discovery tools in the study of plasticity in large-scale brain models

Lämmönsiirto paperin päällysteiden läpi

Diplomityö on tehty Teknillisen korkeakoulun Paperi- ja painatustekniikan laboratorioon yhteistyössä Omya Development AG, Oftringen, Switzerlandin kanssa. Työssä tarkasteltiin lämmönsiirtoa päällystyksessä käytetyn pigmentti-lateksi systeemin läpi. Lämmön siirtyminen päällysteessä on melko uusi tutkimuskohde, jonka tarkoituksena on parantaa ymmärrystä paitsi päällysteiden termisistä ominaisuuksista, mutta hyödyttää lisäksi jälkikäsittelyä sekä jatkojalostusta. Työssä käytettiin päällysteseoksesta paineastiassa muodostettuja ja kuivattuja makroskooppisia tabletteja, joiden pigmenttinä käytettiin kalsiumkarbonaattia ja sideaineena styreeni-akrylaatti-lateksia. Tablettien lateksipitoisuutta vaihdeltiin 8, 12, 20 sekä 25 pph välillä, joiden lisäksi lämmön siirtymistä tableteissa testattiin ilman sideaineita. Rakenteellisten erojen vaikutuksia tutkittiin käyttämällä flokkuloitunutta päällysteseosta sekä käyttämällä tableteille eri kuivatuslämpötiloja. Yksi tavoite oli arvioida lämmön jakautumista tutkimalla toiselta puolelta lämmitetyn tabletin lämpövastetta. Lämpövasteet käsiteltiin kohinanpoisto ja signaalintasoitusmenetelmillä. Lämmönjakautumisen ja lämpöhäviöiden ratkaisemiseen lämpövasteista käytettiin mukautuvaa iterointia. Mittausmenetelmän tarkkuutta arvioitiin sen toistettavuuden pohjalta sekä vertaamalla menetelmän virheettömyyttä tunnettujen referenssimateriaalien termisiin ominaisuuksiin. Tablettien sisäisiä lämpöjakaumia tutkittiin tablettien sisään upotettujen ohuiden termoparien avulla. Sisäisiä lämpöjakaumia tutkittiin kahdella eri menetelmällä, joita vertailtiin keskenään tarkastelemalla tulosten laatua sekä menetelmän sisältämiä virheitä. Sisäisten lämpöjakaumien tuloksia verrattiin lämmönjohtumisen laskennallisiin tuloksiin, jonka pohjalta tarkasteltiin tablettien isotropiaa. Mittausmenetelmä on riittävän tarkka sideaineiden vaikutusten tarkasteluun. On kuitenkin huomattava, että tablettien kuivatus lämpötilojen sekä kosteuspitoisuuksien suhteen tarkkuus ei kuitenkaan ole riittävä. Mittausmenetelmän tarkkuutta oli vaikea määrittää, koska erottelu liitännän rajapinnan ja materiaalin välillä ei ollut mahdollista. Tästä syystä kaikki arvot ovat näennäisarvoja. Suurimmat lämpötilanjohtavuudet mitatuista lämpövasteista saatiin, kun lateksin osuus päällystetabletissa oli 8 osaa. Tämä tarkoittaa sitä, että tällä osuudella saavutetaan parhaat tulokset tabletin pigmenttien pakkaantumisessa sekä kytkeytyneisyydessä. Mittaustulosten laatu on sama molemmilla sisäisten lämpöjakaumien mittausmenetelmällä ja niiden tulokset ovat verrattavissa lämmönjohtumisyhtälön arvoihin. Tulokset viittaavat tablettien rakenteelliseen anisotropiaan tabletin paksuussuunnassa. Jatkotutkimusten tulisi perustua tarkkuuteen ja virheettömyyteen, jotta tarkasteluun voitaisiin liittää useampia parametreja. Tämä mahdollistaisi tarkastelun laajentamisen myös todellisiin paperipäällysteisiin. Lisäksi jatkotutkimuksissa tulisi tehdä mittaustuloksia tukevia huokoisuus- sekä mikroskooppitutkimuksia

Self-Assembly of Gold Nanoparticles at the Oil-Vapor Interface: From Mono- to Multilayers.

Alkylthiol-coated gold nanoparticles spontaneously segregate from dispersion in toluene to the toluene-vapor interface. We show that surface tension drops during segregation with a rate that depends on particle concentration. Mono- and multilayers of particles form depending on particle concentration, time, and temperature. X-ray reflectometry indicates fast monolayer formation and slow multilayer formation. A model that combines diffusion-limited segregation driven by surface energy and heterogeneous agglomeration driven by dispersive van der Waals particle interactions is proposed to describe film formation

Considerations for Medical Transport from the Space Station via an Assured Crew Return Vehicle (ACRV)

In developing a permanently crewed space station, the importance of medical care has been continually reaffirmed; and the health maintenance facility (HMF) is an integral component. It has diagnostic, therapeutic, monitoring, and information management capability. It is designed to allow supportive care for: (1) non-life-threatening illnesses; e.g., headache, lacerations; (2) moderate to severe, possibly life-threatening illnesses; e.g., appendicitis, kidney stones; and (3) severe, incapacitating, life-threatening illnesses; e.g., major trauma, toxic exposure. Since the HMF will not have a general surgical capability, the need for emergency escape and recovery methods has been studied. Medical risk assessments have determined that it is impossible to accurately predict the incidence of crewmember illness/injury. A best estimate is 1:3 per work-year, with 1% of these needing an ACRV. For an eight-person crew, this means that one assured crew return vehicle (ACRV) will be used every 4 to 12 years. The ACRV would serve at least three basic objectives as: (1) a crew return if the space shuttle is unavailable; (2) an escape vehicle from a major time-critical space station emergency; and (3) a full or partial crew return vehicle for a medical emergency. The focus of this paper is the third objective for the ACRV

Self-Assembly of Gold Nanoparticles at the Oil–Vapor Interface: From Mono- to Multilayers

Alkylthiol-coated gold nanoparticles spontaneously segregate from dispersion in toluene to the toluene–vapor interface. We show that surface tension drops during segregation with a rate that depends on particle concentration. Mono- and multilayers of particles form depending on particle concentration, time, and temperature. X-ray reflectometry indicates fast monolayer formation and slow multilayer formation. A model that combines diffusion-limited segregation driven by surface energy and heterogeneous agglomeration driven by dispersive van der Waals particle interactions is proposed to describe film formation