The Effect of Nanocrystalline Cellulose (NCC) Filler on Polylactic Acid (PLA) Nanocomposite Properties

This paper discusses the effect of nanocrystalline cellulose (NCC) when used as filler on polylactic acid (PLA)-based nanocomposites and on its mechanical properties and permeability. NCC was produced from commercial cellulose and another cellulose source, i.e. oil palm empty fruit bunch, by hydrolysis of microcrystalline cellulose with sulphuric acid and by oxidation with ammonium persulfate. The nanocomposites were made by adding nanocrystalline cellulose with varying compositions into PLA. A solvent casting method was used to produce a nanocomposite film with 5% v/v triacetin as a coupling agent. Both methods produced crystalline celluloses within the micro and nano range with mean particle size at 99.5 nm and 157.9 nm for the sulphuric acid hydrolysis and the ammonium persulfate oxidation method, respectively. The utilization of NCC as PLA composite filler increased the percentage of elongation at break with a highest percentage 19.02% for addition of 1% NCC filler. However, higher compositions of cellulosic filler resulted in a decreasing trend of tensile strength and elongation at break. Higher content of NCC filler in the PLA matrix increased the nanocomposite's water vapor permeability

Marginal Deformations of Field Theories with AdS_4 Duals

We generate new AdS_4 solutions of D=11 supergravity starting from AdS_4 x X_7 solutions where X_7 has U(1)^3 isometry. We consider examples where X_7 is weak G_2, Sasaki-Einstein or tri-Sasakian, corresponding to d=3 SCFTs with N=1,2 or 3 supersymmetry, respectively, and where the deformed solutions preserve N=1,2 or 1 supersymmetry, respectively. For the special cases when X_7 is M(3,2), Q(1,1,1) or N(1,1)_I we identify the exactly marginal deformation in the dual field theory. We also show that the volume of supersymmetric 5-cycles of N(1,1)_I agrees with the conformal dimension predicted by the baryons of the dual field theory.Comment: 28 pages, 2 figures; v2. typos correcte

Data Deluge in Astrophysics: Photometric Redshifts as a Template Use Case

Astronomy has entered the big data era and Machine Learning based methods have found widespread use in a large variety of astronomical applications. This is demonstrated by the recent huge increase in the number of publications making use of this new approach. The usage of machine learning methods, however is still far from trivial and many problems still need to be solved. Using the evaluation of photometric redshifts as a case study, we outline the main problems and some ongoing efforts to solve them.Comment: 13 pages, 3 figures, Springer's Communications in Computer and Information Science (CCIS), Vol. 82

Drop impact behaviour on alternately hydrophobic and hydrophilic layered bead packs

A high level of water repellency in soils has an impact on soil hydrology, plant growth and soil erosion. Studies have been performed previously on model soils; consisting of close packed layers of glass spheres (140–400 μm in diameter), to mimic the behaviour of rain water on water repellent soils. In this study measurements were performed on multi-layered bead packs, to assess the interaction of water drops impacting layers consisting of different hydrophobic and hydrophilic layers. A high speed video camera was used to record the impact behaviour of water droplets on the bead packs focussing on the spreading of the droplet and the subsequent rebound behaviour of the droplet. Observations were made from the videos of the liquid marble effect on the droplet, whereby hydrophobic particles form a coating around the droplet, and how it differed depending on the arrangement of hydrophobic and hydrophilic layers within the bead pack. The droplet release height was varied in order to establish a relationship between impact velocity and the degree to which liquid marbling occurs, with higher impact speeds leading to a greater degree of liquid marbling. Measurements were also made to find the transition speeds between the three rebound conditions; rebound, pinning and fragmentation, showing an overall decrease in pinning velocity as the bead size increased

Universality of Performance Indicators based on Citation and Reference Counts

We find evidence for the universality of two relative bibliometric indicators of the quality of individual scientific publications taken from different data sets. One of these is a new index that considers both citation and reference counts. We demonstrate this universality for relatively well cited publications from a single institute, grouped by year of publication and by faculty or by department. We show similar behaviour in publications submitted to the arXiv e-print archive, grouped by year of submission and by sub-archive. We also find that for reasonably well cited papers this distribution is well fitted by a lognormal with a variance of around 1.3 which is consistent with the results of Radicchi, Fortunato, and Castellano (2008). Our work demonstrates that comparisons can be made between publications from different disciplines and publication dates, regardless of their citation count and without expensive access to the whole world-wide citation graph. Further, it shows that averages of the logarithm of such relative bibliometric indices deal with the issue of long tails and avoid the need for statistics based on lengthy ranking procedures.Comment: 15 pages, 14 figures, 11 pages of supplementary material. Submitted to Scientometric

The UN in the lab

We consider two alternatives to inaction for governments combating terrorism, which we term Defense and Prevention. Defense consists of investing in resources that reduce the impact of an attack, and generates a negative externality to other governments, making their countries a more attractive objective for terrorists. In contrast, Prevention, which consists of investing in resources that reduce the ability of the terrorist organization to mount an attack, creates a positive externality by reducing the overall threat of terrorism for all. This interaction is captured using a simple 3×3 “Nested Prisoner’s Dilemma” game, with a single Nash equilibrium where both countries choose Defense. Due to the structure of this interaction, countries can benefit from coordination of policy choices, and international institutions (such as the UN) can be utilized to facilitate coordination by implementing agreements to share the burden of Prevention. We introduce an institution that implements a burden-sharing policy for Prevention, and investigate experimentally whether subjects coordinate on a cooperative strategy more frequently under different levels of cost sharing. In all treatments, burden sharing leaves the Prisoner’s Dilemma structure and Nash equilibrium of the game unchanged. We compare three levels of burden sharing to a baseline in a between-subjects design, and find that burden sharing generates a non-linear effect on the choice of the efficient Prevention strategy and overall performance. Only an institution supporting a high level of mandatory burden sharing generates a significant improvement in the use of the Prevention strategy

Selective ROCK2 inhibition in focal cerebral ischemia

Objective: Rho-associated kinase (ROCK) is a key regulator of numerous processes in multiple cell types relevant in stroke pathophysiology. ROCK inhibitors have improved outcome in experimental models of acute ischemic or hemorrhagic stroke. However, the relevant ROCK isoform (ROCK1 or ROCK2) in acute stroke is not known. Methods: We characterized the pharmacodynamic and pharmacokinetic profile, and tested the efficacy and safety of a novel selective ROCK2 inhibitor KD025 (formerly SLx-2119) in focal cerebral ischemia models in mice. Results: KD025 dose-dependently reduced infarct volume after transient middle cerebral artery occlusion. The therapeutic window was at least 3 h from stroke onset, and the efficacy was sustained for at least 4 weeks. KD025 was at least as efficacious in aged, diabetic or female mice, as in normal adult males. Concurrent treatment with atorvastatin was safe, but not additive or synergistic. KD025 was also safe in a permanent ischemia model, albeit with diminished efficacy. As one mechanism of protection, KD025 improved cortical perfusion in a distal middle cerebral artery occlusion model, implicating enhanced collateral flow. Unlike isoform-nonselective ROCK inhibitors, KD025 did not cause significant hypotension, a dose-limiting side effect in acute ischemic stroke. Interpretation Altogether, these data show that KD025 is efficacious and safe in acute focal cerebral ischemia in mice, implicating ROCK2 as the relevant isoform in acute ischemic stroke. Data suggest that selective ROCK2 inhibition has a favorable safety profile to facilitate clinical translation

Continuous Brain-derived Neurotrophic Factor (BDNF) Infusion After Methylprednisolone Treatment in Severe Spinal Cord Injury

Although methylprednisolone (MP) is the standard of care in acute spinal cord injury (SCI), its functional outcome varies in clinical situation. Recent report demonstrated that MP depresses the expression of growth-promoting neurotrophic factors after acute SCI. The present study was designed to investigate whether continuous infusion of brain-derived neurotrophic factor (BDNF) after MP treatment promotes functional recovery in severe SCI. Contusion injury was produced at the T10 vertebral level of the spinal cord in adult rats. The rats received MP intravenously immediately after the injury and BDNF was infused intrathecally using an osmotic mini-pump for six weeks. Immunohistochemical methods were used to detect ED-1, Growth associated protein-43 (GAP-43), neurofilament (NF), and choline acethyl transferase (ChAT) levels. BDNF did not alter the effect of MP on hematogenous inflammatory cellular infiltration. MP treatment with BDNF infusion resulted in greater axonal survival and regeneration compared to MP treatment alone, as indicated by increases in NF and GAP-43 gene expression. Adjunctive BDNF infusion resulted in better locomotor test scores using the Basso-Beattie-Bresnahan (BBB) test. This study demonstrated that continuous infusion of BDNF after initial MP treatment improved functional recovery after severe spinal cord injury without dampening the acute effect of MP

Whole Body Mechanics of Stealthy Walking in Cats

The metabolic cost associated with locomotion represents a significant part of an animal's metabolic energy budget. Therefore understanding the ways in which animals manage the energy required for locomotion by controlling muscular effort is critical to understanding limb design and the evolution of locomotor behavior. The assumption that energetic economy is the most important target of natural selection underlies many analyses of steady animal locomotion, leading to the prediction that animals will choose gaits and postures that maximize energetic efficiency. Many quadrupedal animals, particularly those that specialize in long distance steady locomotion, do in fact reduce the muscular contribution required for walking by adopting pendulum-like center of mass movements that facilitate exchange between kinetic energy (KE) and potential energy (PE) [1]–[4]. However, animals that are not specialized for long distance steady locomotion may face a more complex set of requirements, some of which may conflict with the efficient exchange of mechanical energy. For example, the “stealthy” walking style of cats may demand slow movements performed with the center of mass close to the ground. Force plate and video data show that domestic cats (Felis catus, Linnaeus, 1758) have lower mechanical energy recovery than mammals specialized for distance. A strong negative correlation was found between mechanical energy recovery and diagonality in the footfalls and there was also a negative correlation between limb compression and diagonality of footfalls such that more crouched postures tended to have greater diagonality. These data show a previously unrecognized mechanical relationship in which crouched postures are associated with changes in footfall pattern which are in turn related to reduced mechanical energy recovery. Low energy recovery was not associated with decreased vertical oscillations of the center of mass as theoretically predicted, but rather with posture and footfall pattern on the phase relationship between potential and kinetic energy. An important implication of these results is the possibility of a tradeoff between stealthy walking and economy of locomotion. This potential tradeoff highlights the complex and conflicting pressures that may govern the locomotor choices that animals make