The role of long-range forces in the phase behavior of colloids and proteins

The phase behavior of colloid-polymer mixtures, and of solutions of globular proteins, is often interpreted in terms of a simple model of hard spheres with short-ranged attraction. While such a model yields a qualitative understanding of the generic phase diagrams of both colloids and proteins, it fails to capture one important difference: the model predicts fluid-fluid phase separation in the metastable regime below the freezing curve. Such demixing has been observed for globular proteins, but for colloids it appears to be pre-empted by the appearance of a gel. In this paper, we study the effect of additional long-range attractions on the phase behavior of spheres with short-ranged attraction. We find that such attractions can shift the (metastable) fluid-fluid critical point out of the gel region. As this metastable critical point may be important for crystal nucleation, our results suggest that long-ranged attractive forces may play an important role in the crystallization of globular proteins. However, in colloids, where refractive index matching is often used to switch off long-ranged dispersion forces, gelation is likely to inhibit phase separation.Comment: EURO-LATEX, 6 pages, 2 figure

Hybrid PCM\u2014aluminium foams\u2019 thermal storages: an experimental study

The latent heat absorption phenomenon associated with melting of a suitable Phase Change Material can be an effective way to improve the Thermal Energy Storage behaviour in many applications. However, the most suitable materials to be used in heating and refrigeration systems find intrinsic limitations due to their poor heat transfer capabilities. This work experimentally studies the use of aluminum foams as heat transfer medium to improve the overall heat transfer of paraffin waxes that can be possible phase change materials to be implemented in hybrid sensible-latent water thermal energy storages. The experimental tests were run in a dedicated setup designed, developed, and built at the Department of Management and Engineering of the University of Padova. The effects of the use of aluminum foams as enhancing heat transfer medium were studied by comparing the loading and unloading processes of a paraffin wax with melting temperature around 40 \ub0C, with and without metal foams, in a water thermal storage unit. The effects of three different foams with 5, 20, and 40 Pores Per Inch (PPI) were investigated

PVT and ETC coupling for annual heating and cooling by absorption heat pumps

Until recently, solar assisted heat pumps have used solar collectors as a cold source. Solar collectors provide, when possible, direct heat, otherwise they offer temperature levels to the heat pump evaporator higher than the outside air. At the same time, solar thermal cooling exploits the solar collectors and the absorption chiller only in hot months. Photovoltaic/Thermal (PVT) modules have been available on the market in recent years for solar cogeneration, but their utilization can be problematic due to PhotoVoltaic (PV) cell damage in cases where there is no heating request. This paper considers the possibility of coupling evacuated tube collectors and photovoltaic/thermal modules to drive an absorption heat pump-based plant operating as an absorption chiller in the summertime. The cold source is the solar energy and the ground, which is recharged by the solar thermal and photovoltaic/thermal collectors and by the cooling of the absorber-condenser in mid-seasons and summer. This study analyzes the system behavior in yearly operation and evaluates the role of suitable storage tanks in two different climates, varying the size of the two solar fields and the generator tank. In the best plant configuration, a primary energy ratio of 26.6 in colder climates with cloudy skies and 20 in hotter climates with clearer skies is obtained

Energy analysis of industrial climatization by an innovative radiant condensing system

Radiant heating plants have become increasingly popular in the last decades, particularly for industrial applications. Generally, they are high temperature radiant heating type, even if more recently low temperature radiant floors have increased their spread due to the increased thermal insulation of buildings. Moreover, radiant floors allow for cooling as well. In this paper, energy performance of a high temperature radiant tubes heating plant coupled to a condensing system for the climatization of an industrial building are investigated by dynamic simulation. A Trnsys type is modified in order to simulate the behavior of the high temperature condensing system: both the radiative (between the heating and the surrounding surfaces) and the convective heat exchanges with suitable devices (like baffles applied in order to reduce convection and consequent thermal stratification) are considered. Energy performance is compared to that of two more traditional plants such as warm air heater, and low temperature radiant floor coupled to condensing boiler. Finally, some considerations about the energy performance of the radiant tubes system in cooling mode are reported

Energy performance of water strip modules for industrial heating in real operation conditions: Steady-state and CFD analyses

The objective of this study is the theoretical evaluation of the energy performance of a radiant strips heating system fed with hot water by varying the operating conditions. First, the convective coefficients and the heating power (both convective and radiant parts) of the heating system are evaluated in steady-state conditions by simulating heat exchange similar to real operating conditions (such as the presence of a ventilation system, the opening of doors, windows, or skylights, etc.), in comparison with the nominal data. To carry out this preliminary assessment, different references in the scientific literature are considered with respect to experimental measurements and numerical simulations for similar applications. The steady-state analysis revealed that the increase in the overall yield of the heating strips, compared to the data measured according to the EN 14,037 standard, is in the order of 30%. Afterward, a CFD analysis is reported to dynamically study the effect of the above-mentioned typical situations of real operation of the system in industrial sheds. The CFD analysis confirms that the presence of constant air exchange leads to an improvement of more than 30% in the performance of the water strip system. The main conclusion is that designing the water strip system following the EN 14,037 standard probably will oversize the industrial heating plant

Predicting Rising Follower Counts on Twitter Using Profile Information

When evaluating the cause of one's popularity on Twitter, one thing is considered to be the main driver: Many tweets. There is debate about the kind of tweet one should publish, but little beyond tweets. Of particular interest is the information provided by each Twitter user's profile page. One of the features are the given names on those profiles. Studies on psychology and economics identified correlations of the first name to, e.g., one's school marks or chances of getting a job interview in the US. Therefore, we are interested in the influence of those profile information on the follower count. We addressed this question by analyzing the profiles of about 6 Million Twitter users. All profiles are separated into three groups: Users that have a first name, English words, or neither of both in their name field. The assumption is that names and words influence the discoverability of a user and subsequently his/her follower count. We propose a classifier that labels users who will increase their follower count within a month by applying different models based on the user's group. The classifiers are evaluated with the area under the receiver operator curve score and achieves a score above 0.800.Comment: 10 pages, 3 figures, 8 tables, WebSci '17, June 25--28, 2017, Troy, NY, US

Neutron Scattering and magnetization studies of Ba2_2Cu2.95_{2.95}Co0.05_{0.05}O4_4Cl2_2: A decorated two-dimensional antiferromagnet

Ba$_2$Cu$_3$O$_4$Cl$_2$ has two inter-penetrating square Cu sublattices, one with square root 2 times the in-plane spacing of the other. Isotropic magnetic interactions between the two sublattices are completely frustrated. Quantum fluctuations resolve the intrinsic degeneracy in the ordering direction of the more weakly coupled sublattice in favor of collinear ordering. We present neutron scattering and magnetization studies of the magnetic structure when the Cu ions are substituted with Co. The Co spins create new magnetic interactions between the two sublattices. The ordering behavior of both Cu sublattices is retained largely unmodified. Between the phase transitions of the two sublattices spin-glass behavior is observed. Magnetization results show a strong enhancement to the ferromagnetic aspect of the magnetic structure. The combination of glassy behavior and large moments strongly suggest that the Co moments induce the formation of local canted states.Comment: 4 figure

Hemoglobinuria posparto en vacas de tres rebaños lecheros de la región del Bío-Bío, Chile

RESUMEN La hemoglobinuria posparto es una enfermedad metabólica esporádica que presentanlas vacas lecheras, manifestándose dentro de las 6 semanas posparto asociada al rápidoincremento de la producción de leche al inicio de la lactancia. Se caracteriza por una anemiaaguda regenerativa por hemólisis intravascular con hemoglobinuria. Entre los factores quepredisponen a su presentación están la ingesta de una dieta carente en fósforo, cobre oselenio, o bien concomitante a la presencia de agentes hemolíticos en plantas crucíferascomo el nabo o colza. El trabajo describe aspectos relacionados a la presentación de brotesde la enfermedad en tres rebaños lecheros de la región del Bío-bío, Chile, con hipofosfatemiaasociada a la incorporación de derivados de la remolacha azucarera en la dieta

Study of nuclear correlation effects via 12C(p,n)12N(g.s.,1+) at 296 MeV

We report measurements of the cross section and a complete set of polarization observables for the Gamow--Teller ${}^{12}{\rm C}(\vec{p},\vec{n}){}^{12}{\rm N}({\rm g.s.},1^+)$ reaction at a bombarding energy of 296 MeV. The data are compared with distorted wave impulse approximation calculations employing transition form factors normalized to reproduce the observed beta-decay $ft$ value. The cross section is significantly under-predicted by the calculations at momentum transfers $q \gtrsim$ 0.5 ${\rm fm^{-1}}$. The discrepancy is partly resolved by considering the non-locality of the nuclear mean field. However, the calculations still under-predict the cross section at large momentum transfers of $q$ $\simeq$ 1.6 ${\rm fm^{-1}}$. We also performed calculations employing random phase approximation response functions and found that the observed enhancement can be attributed in part to pionic correlations in nuclei.Comment: 5 figures, submitted to Phys. Lett.

Thin Ice Target for 16^{16}O(p,p') experiment

A windowless and self-supporting ice target is described. An ice sheet with a thickness of 29.7 mg/cm$^2$ cooled by liquid nitrogen was placed at the target position of a magnetic spectrometer and worked stably in the $^{16}$O$(p,p')$ experiment at $E_{p}=392$ MeV. Background-free spectra were obtained.Comment: 14 pages, 4 figures, Nucl. Instr. & Meth. A (in press