Analysis of infrared optical polishing effluents and reduction of COD and TSS levels by ultrafiltration and coagulation/flocculation

Samples of polishing effluent produced during infrared optics manufacture were analyzed. Their particle size, composition, Zeta potential, chemical oxygen demand (COD), total suspended solids (TSS), and settleable solids were determined. Feasibility of treatment methods such as ultrafiltration (UF) and coagulation/flocculation was investigated to reduce both COD and TSS. It was found that effluents consisted of a suspension of micro- and nanoparticles. Effluent particle size distribution reflected the removal rate of the originating polishing process. Their composition was primarily germanium and other polished substrates as well as polishing abrasives. The effluent Zeta potential was highly negative and prevented particle settling. COD of all specimens was very high, which prevented sewage discharge. Laboratory-scale trials using UF showed substantial COD abatement of up to 74.1%. TSS was reduced to zero after UF. Comparable coagulation/flocculation COD abatement was demonstrated for the highest COD sample

Results from the CASTLES Survey of Gravitational Lenses

We show that most gravitational lenses lie on the passively evolving fundamental plane for early-type galaxies. For burst star formation models (1 Gyr of star formation, then quiescence) in low Omega_0 cosmologies, the stellar populations of the lens galaxies must have formed at z_f > 2. Typical lens galaxies contain modest amounts of patchy extinction, with a median differential extinction for the optical (radio) selected lenses of E(B-V) = 0.04 (0.07) mag. The dust can be used to determine both extinction laws and lens redshifts. For example, the z_l=0.96 elliptical lens in MG0414+0534 has an R_V=1.7 +/- 0.1 mean extinction law. Arc and ring images of the quasar and AGN source host galaxies are commonly seen in NICMOS H band observations. The hosts are typically blue, L < L_* galaxies.Comment: 12 pages, 10 figures, from Proceedings of the 9th Annual Astrophysics Conference in Maryland, After the Dark Ages: When Galaxies Were Youn

Found: High Surface Brightness Compact Galaxies

We are using the 2dF spectrograph to make a survey of all objects (`stars' and `galaxies') in a 12 sq.deg region towards the Fornax cluster. We have discovered a population of compact emission-line galaxies unresolved on photographic sky survey plates and therefore missing in most galaxy surveys based on such material. These galaxies are as luminous as normal field galaxies. Using H-alpha to estimate star formation they contribute at least an additional 5 per cent to the local star formation rate.Comment: To appear in "The Low Surface Brightness Universe", IAU Coll 171, eds. J.I. Davies et al., A.S.P. Conference Series. 3 pages, LaTex, 1 encapsulated ps-figure, requires paspconf.st

A new method for the estimate of H_0 from quadruply imaged gravitational lens systems

We present a new method to estimate the Hubble constant H_0 from the measured time delays in quadruply imaged gravitational lens systems. We show how it is possible to get an estimate of H_0 without the need to completely reconstruct the lensing potential thus avoiding any a priori hypotheses on the expression of the galaxy lens model. Our method only needs to assume that the lens potential may be expressed as r^{\alpha} F(\theta), whatever the shape function F(\theta) is, and it is thus able to fully explore the degeneracy in the mass models taking also into account the presence of an external shear. We test the method on simulated cases and show that it does work well in recovering the correct value of the slope \alpha of the radial profile and of the Hubble constant H_0. Then, we apply the same method to the real quadruple lenses PG1115+080 and B1422+231 obtaining H_0 = 58_{-15}^{+17} km/s/Mpc (68% CL).Comment: 12 pages, 5 figures, accepted for publication on Astronomy & Astrophysic

Additive Manufacturing and Physicomechanical Characteristics of PEGDA Hydrogels: Recent Advances and Perspective for Tissue Engineering

In this brief review, we discuss the recent advancements in using poly(ethylene glycol) diacrylate (PEGDA) hydrogels for tissue engineering applications. PEGDA hydrogels are highly attractive in biomedical and biotechnology fields due to their soft and hydrated properties that can replicate living tissues. These hydrogels can be manipulated using light, heat, and cross-linkers to achieve desirable functionalities. Unlike previous reviews that focused solely on material design and fabrication of bioactive hydrogels and their cell viability and interactions with the extracellular matrix (ECM), we compare the traditional bulk photo-crosslinking method with the latest three-dimensional (3D) printing of PEGDA hydrogels. We present detailed evidence combining the physical, chemical, bulk, and localized mechanical characteristics, including their composition, fabrication methods, experimental conditions, and reported mechanical properties of bulk and 3D printed PEGDA hydrogels. Furthermore, we highlight the current state of biomedical applications of 3D PEGDA hydrogels in tissue engineering and organ-on-chip devices over the last 20 years. Finally, we delve into the current obstacles and future possibilities in the field of engineering 3D layer-by-layer (LbL) PEGDA hydrogels for tissue engineering and organ-on-chip devices

Enhanced heterogeneous nucleation on oxides in Al alloys by intensive shearing

Oxides, in liquid aluminium alloys, can cause severe difficulties during casting, contribute to the formation of cast defects and degrade the mechanical properties of cast components. In this paper, microstructural characteristics of naturally occurring oxides in the melts of commercial purity aluminium and Al-Mg binary alloys have been investigated. They are characterised by densely populated oxide particles within liquid oxide films. With intensive shearing, the particle agglomerates are dispersed into uniformly distributed individual particles. It was found that with intensive melt shearing, grain refinement of α-Al can be achieved by the dispersed oxide particles. The smaller lattice misfit between the oxide particles and the α-Al phase is characterised by a well defined crystallographic orientation relationship. And the mechanisms of grain refinement are discussed.The EPSR

Nutritional Manipulation of Exercise Induced Skeletal Muscle Cell Signalling: Implications for Acute Training Adaptations

Traditional nutritional approaches for endurance training typically advise high carbohydrate (CHO) availability before, during and after each training session to suppor high training volume, intensity and recovery. However, during the last decade, accumulating data demonstrate that carefully scheduled periods of reduced CHO availability actually augment training-induced oxidative adaptations of skeletal muscle, the so-called train-low paradigm. In accordance with this movement there is also growing rationale ot consume protein before, during and/or after train-low sessions in an attempt to simultaneously promote mitochondrial biogenesis, muscle protein synthesis (MPS) and improve net muscle protein balance. The aim of this thesis was to assess the effects of reduced CHO but high protein availability on the regulation of molecular pathways associated with modulation of the aforementioned components of training adaptation. On the basis of characterising such molecular responses, a secondary aim was to formulate a nevel framework for which to practically apply train-low paradigms. Given the enhanced oxidative adaptatios observed when training in CHO restricted state is potentially regulated through free fatty acid (FFA)-mediated signalling, the aim of study 1 (chapter 4) was to test the hypothesis that leucine-enriched protein feeding before and during exercise does not impair FFA availability or whole body lipid oxidation during exercise. Here I utulised a novel leucine enriched protein gel and compaired this agains a whey drink or placebo gel in a repeated masures design. This study showed that despite the insulemic effects of protein provision, there was no imparment in FFA availability or whole body lipid oxidation during exercise. Therefore, suggesting that protein feeding does not hinder a key objective of train-low sessions. Building on the results from study 1, I next saught to characterise the effects of reduced CHO but high leucine availability on exercise capacity and cell-signalling responses associated with exercise-induced regulation of mitochondrial biogenesis and MPS. While low CHO availability inhibited exercise capacity, comparible mitochondrial signalling responces were seen at the point of fatigue despite participants performing significantly more work in high CHO condition. This demonstrated that training with low CHO is work-efficient in eliciting beneficial signals regulating mitochondrial biogenesis. Despite providing leucine rich protein before, during and after exercise, MPS related signalling could not be rescued during the CHO restriced post-exercise period in the low CHO condition. The data from this study suggest that although there are potential metabolic benefits associated with reduced pre-exercise CHO availability, the post-exercise meal should contain sufficient CHO to restore muscle glycogen to sufficient levels and/or provide the nexessary energy to support post-exercise remodelling process. Having identified the potential detrimental effects of low CHO recovery, the aim of study 3 (Chapter 6) was to examine the role of leucine availability in regulating post-exercise skeletal muscle remodelling processes in recovery from a train-low training session. Here I fed one of two protein types, a collagen (naturally low in leucine) or a whey (naturally high in leucine) protein during a low CHO training session, in a repeated measures design. When considered with study 2, the data from this study suggested that leucine is essential for reactivation of signalling mechanisms involved in protein translation, interestingly while low CHO training appeared to activate components of the system that selectively degrades malfunctional parts of the cell, leucine content had no effect on these processes. When taken together, the novel data presented in this thesis allude to a potential muscle glycogen threshold hypothesis surmising that reduced pre-exercise muscle glycogen may enhance the activation of those pathways regulating mitochondrial biogenesis but also suggest that keeping glycogen (and energy) at critically low levels may impair the regulation if post-exercise remodelling processes. From a practical perspective, data lend support for a potential “fuel for the work required” train-low paradigm in that athletes could strategically reduce CHO availability prior to completing pre-determined training workloads that can be redily performed with reduced CHO availability, thereby inducing a work efficient approach to training. Alternativly, when the goals of the training session are to complete the highest workload possible over more prolonged duration, then adequate CHO should be provided prior to and during the specific training session

The z<=0.1 Surface Brightness Distribution

The surface brightness distribution (SBD) function describes the number density of galaxies as measured against their central surface brightness. Because detecting galaxies with low central surface brightnesses is both time-consuming and complicated, determining the shape of this distribution function can be difficult. In a recent paper Cross, et al. suggested a bell-shaped SBD disk-galaxy function which peaks near the canonical Freeman value of 21.7 and then falls off significantly by 23.5 B mag arcsec-2. This is in contradiction to previous studies which have typically found flat (slope=0) SBD functions out to 24 - 25 B mag arcsec^-2 (the survey limits). Here we take advantage of a recent surface-brightness limited survey by Andreon & Cuillandre which reaches considerably fainter magnitudes than the Cross, et.al sample (M_B reaches fainter than -12 for Andreon & Cuillandre while the Cross, et.al sample is limited to M_B < -16) to re-evaluate both the SBD function as found by their data and the SBD for a wide variety of galaxy surveys, including the Cross, et al. data. The result is a SBD function with a flat slope out through the survey limits of 24.5 B mag arcsec^-2, with high confidence limits.Comment: 5 pages including 5 figures. accepted by A&A

Lensed Quasar Hosts

Gravitational lensing assists in the detection of quasar hosts by amplifying and distorting the host light away from the unresolved quasar core images. We present the results of HST observations of 30 quasar hosts at redshifts 1 < z < 4.5. The hosts are small in size (r_e <~ 6 kpc), and span a range of morphologies consistent with early-types (though smaller in mass) to disky/late-type. The ratio of the black hole mass (MBH, from the virial technique) to the bulge mass (M_bulge, from the stellar luminosity) at 1<z<1.7 is broadly consistent with the local value; while MBH/M_bulge at z>1.7 is a factor of 3--6 higher than the local value. But, depending on the stellar content the ratio may decline at z>4 (if E/S0-like), flatten off to 6--10 times the local value (if Sbc-like), or continue to rise (if Im-like). We infer that galaxy bulge masses must have grown by a factor of 3--6 over the redshift range 3>z>1, and then changed little since z~1. This suggests that the peak epoch of galaxy formation for massive galaxies is above z~1. We also estimate the duty cycle of luminous AGNs at z>1 to be ~1%, or 10^7 yrs, with sizable scatter.Comment: 8 pages, 6 figures, review article with C. Impey at the conference on "QSO Host Galaxies: Evolution and Environment", Aug. 29-Sep. 2, 2005, Lorentz Center, Leiden, The Netherland