Studies of some properties of hydroxide-catalysis bonds

Jointing materials is an inevitable step in the fabrication of many high performance optical devices. Today there is an increasing demand, both from industry and academic research, for reliable techniques for jointing of optical components which can be performed simply and inexpensively, where the bonds possess high strength and precision with low mechanical loss. Several methods of bonding have been defined and employed over time. Currently, the most common techniques of bonding are optical contacting, diffusion, epoxy and glass frit. Each of these techniques has positive aspects which make them appropriate for a range of applications, but not ideal in cases where a thin optically transparent and mechanically strong joint between optical compounds is required. Hydroxide-catalysis bonding is an interesting candidate in such cases: it has already been demonstrated to have excellent performance with respect to mechanical stability, precision and strength in numerous applications, such as in space systems, optics and gravitational wave detectors. At present, there are not many papers that talk exhaustively about the optical properties of hydroxide-catalysis bonding. Most of the time, the published results are closely dependent on requirements imposed by the experiment that is being conducted. Since there are a lot of interesting potential applications and increasing industrial interest in usage of hydroxide-catalysis bonding, it is important to develop techniques to characterise the optical properties of these bonds. In this thesis, a non-destructive technique for measuring the optical properties of hydroxide-catalysis bonding is reported. More specifically, the bond refractive index and thickness are determined from reflectivity measurements. By applying this method, it will be possible to understand how the optical properties and chemistry of a hydroxide-catalysis bond vary when different bonding solutions and substrate materials are used and, consequently, to tailor better the bonds to various utilisations of interest. Sodium silicate solution at different concentrations with water and potassium hydroxide solution are used to bond fused silica and sapphire substrates. Curing at room temperature and at 100 °C for eight hours is chosen to study the influence of temperature on the properties of a hydroxide-catalysis bond. It was found that the bond optical reflectivities are less than 1% for fused silica samples and less than 10% for sapphire samples and they decrease over time. Bond refractive indices start from a value close to the refractive index of water and approach the refractive index of fused silica as the cure proceeds. Bond thicknesses cured at room temperature decrease over time plateauing at a more or less constant value, different for each case studied (about a few hundred nanometres), whereas bond thicknesses cured at high temperature seem to increase over time (less than about 400 nanometres)

Fast UPLC/PDA determination of squalene in Sicilian P.D.O. pistachio from Bronte: optimization of oil extraction method and analytical characterization

A fast reversed-phase UPLC method was developed for squalene determination in Sicilian pistachio samples that entry in the European register of the products with P.D.O. In the present study the SPE procedure was optimized for the squalene extraction prior to the UPLC/PDA analysis. The precision of the full analytical procedure was satisfactory and the mean recoveries were 92.8 ± 0.3 % and 96.6 ± 0.1 % for 25 and 50 mg L-1 level of addition, respectively. Selected chromatographic conditions allowed a very fast squalene determination; in fact it was well separated in ∼ 0.54 min with good resolution. Squalene was detected in all the pistachio samples analyzed and the levels ranged from 55.45 to 226.34 mg . kg-1. Comparing our results with those of other studies it emerges that squalene contents in P.D.O. Sicilian pistachio samples, generally, were higher than those measured for other samples of different geographic origins

Test facility for experimental investigations of the He-II based ET-LF payload cooling concept

The Einstein Telescope (ET) is a third generation gravitational wave detector, combining a low-frequency (LF) and a high-frequency (HF) laser interferometer. Cryogenic operation of ET-LF in the temperature range of 10-20 K is essential to suppress the suspension thermal noise (STN), which dominates the detection sensitivity at frequencies below 10 Hz. The minimization of the STN requires suspension materials with high thermal conductivity and low mechanical dissipation at cryogenic temperatures. Motivated by the exceptional heat conductivity of static He-II and a presumably low dissipation, a new marionette suspension design with a He-II filled titanium tube has been proposed and, theoretically, shown to meet the ET-D sensitivity requirements. The concept includes open fundamental questions that can only be addressed by measurements of the mechanical Q-factor, providing crucial insights in the dissipative behaviour of such a system. Hence, an experimental setup for cryogenic Q-factor measurements is being planned. The scope of experiments and a first conceptual design are being presented here. Beside the Q-factor measurements, a main focus of this facility is given to R&D on the integration of the He-II system and the mechanical interface to the payload in view of noise isolation

Conceptual cryostat design for cryogenic suspension studies for the Einstein Telescope

The Einstein Telescope (ET) is a third generation gravitational wave detector, combining a low-frequency (LF) and a high-frequency (HF) laser interferometer. Cryogenic operation of ET-LF in the temperature range of 10K to 20K is essential to suppress the suspension thermal noise, which dominates the detection sensitivity at frequencies below 10 Hz. This requires suspension materials with high thermal conductivity and low mechanical dissipation at cryogenic temperatures. Two possible suspension concepts are currently considered, using either monocrystalline suspension fibers made of silicon or sapphire, or titanium suspension tubes filled with static He-II. The dissipative behavior of these suspensions is characterized by the mechanical Q-factor. It can be measured by the ring-down method, exciting the suspensions to resonance vibrations on the nanometer scale and analyzing the decay time. For this purpose, a new cryogenic test facility is being planned, allowing the investigation of cryogenic payload suspensions for third-generation gravitational wave detectors. The test cryostat is equipped with a cryocooler and enables real-size studies with various suspension materials and geometries. The future integration of He-II is foreseen to enable He-II filled suspension studies. We describe the scope of experiments and the conceptual design of the test cryostat

Detection of Plasmodium falciparum male and female gametocytes and determination of parasite sex ratio in human endemic populations by novel, cheap and robust RTqPCR assays

The presence of Plasmodium falciparum gametocytes in peripheral blood is essential for human to mosquito parasite transmission. The detection of submicroscopic infections with gametocytes and the estimation of the gametocyte sex ratio are crucial to assess the human host potential ability to infect mosquitoes and transmit malaria parasites

Differential antibody response to the Anopheles gambiae gSG6 and cE5 salivary proteins in individuals naturally exposed to bites of malaria vectors.

Background Mosquito saliva plays crucial roles in blood feeding but also evokes in hosts an anti-saliva antibody response. The IgG response to the Anopheles gambiae salivary protein gSG6 was previously shown to be a reliable indicator of human exposure to Afrotropical malaria vectors. We analyzed here the humoral response to the salivary anti-thrombin cE5 in a group of individuals from a malaria hyperendemic area of Burkina Faso. Methods ELISA was used to measure the anti-cE5 IgG, IgG1 and IgG4 antibody levels in plasma samples collected in the village of Barkoumbilen (Burkina Faso) among individuals of the Rimaibé ethnic group. Anti-gSG6 IgG levels were also determined for comparison. Anopheles vector density in the study area was evaluated by indoor pyrethrum spray catches. Results The cE5 protein was highly immunogenic and triggered in exposed individuals a relatively long-lasting antibody response, as shown by its unchanged persistence after a few months of absent or very low exposure (dry season). In addition cE5 did not induce immune tolerance, as previously suggested for the gSG6 antigen. Finally, IgG subclass analysis suggested that exposed individuals may mount a Th1-type immune response against the cE5 protein. Conclusions The anti-cE5 IgG response is shown here to be a sensitive indicator of human exposure to anopheline vectors and to represent an additional tool for malaria epidemiological studies. It may be especially useful in conditions of low vector density, to monitor transiently exposed individuals (i.e. travellers/workers/soldiers spending a few months in tropical Africa) and to evaluate the impact of insecticide treated nets on vector control. Moreover, the gSG6 and cE5 salivary proteins were shown to trigger in exposed individuals a strikingly different immune response with (i) gSG6 evoking a short-lived IgG response, characterized by high IgG4 levels and most likely induction of immune tolerance, and (ii) cE5 eliciting a longer-living IgG response, dominated by anti-cE5 IgG1 antibodies and not inducing tolerance mechanisms. We believe that these two antigens may represent useful reagents to further investigate the so far overlooked role of Anopheles saliva and salivary proteins in host early immune response to Plasmodium parasites

Molecular Portrait of Clear Cell Renal Cell Carcinoma: An Integrative Analysis of Gene Expression and Genomic Copy Number Profiling

Renal cell carcinoma (RCC) incidence accounts for about 3 to 10 cases per 100,000 individuals with a predilection for adult males over 60 year old (1.6:1 male/female ratio) (Chow, 2010; Nese, 2009). In Europe, about 60,000 individuals are affected by RCC every year, with a mortality rate of about 18,000 subjects and an incidence rate for all stages steadily rising over the last three decades. Although inherited forms occur in a number of familial cancer syndromes, as the well-known von Hippel-Lindau (VHL) syndrome, RCC is commonly sporadic (Cohen & McGovern, 2005; Kaelin, 2007) and, as recently highlighted by the National Cancer Institute (NCI), influenced by the interplay between exposure to environmental risk factors and genetic susceptibility of exposed individuals (Chow et al., 2010). Being poorly symptomatic in early phases, many cases become clinically detectable only when already advanced and, as such, therapy-resistant (Motzer, 2011). Based on histology, RCC can be classified into several subtypes, i.e., clear cell (80% of cases), papillary (10%), chromophobe (5%) and oncocytoma (5%), each one characterized by specific histo- pathological features, malignant potential and clinical outcome (Cohen & McGovern, 2005). Patient stratification is normally achieved using prognostic algorithms and nomograms based on multiple clinico-pathological factors such as TNM stage, Fuhrman nuclear grade, tumor size, performance status, necrosis and other hematological indices (Flanigan et al., 2011), although the most efficient predictors of survival and recurrence are based on nuclear grade alone (Nese et al., 2009). As recently reviewed by Brannon et al. (Brannon & Rathmell, 2010), a finer RCC subtype classification could be obtained exploiting the vast amount of genomic and transcriptional data that have been presented in numerous studies. For instance, several authors proposed a molecular classification of RCC based on differential gene expression profiles, with any subtype characterized by the activation of distinct gene sets (Brannon, 2010; Furge, 2004; Skubitz, 2006; Su\u308ltmann, 2005; Zhang, 2008), while others identified RCC-specific biomarkers (e.g. CA9, ki67, VEGF proteins, phosphorylated AKT, PTEN, HIF-1). Lately, it has been reported that microRNAs, a small class of non coding RNA molecules, could contribute to RCC development at different levels and may represent a new group of potential tumor biomarkers (Redova et al., 2011). Despite the numerous efforts in dissecting the molecular features of RCC through functional genomics, not a single transcriptional signature or biomarker has gained approval for clinical application yet (Arsanious, 2009; Eichelberg, 2009; Lam, 2007; Yin-Goen, 2006), so that the identification of novel molecular markers to improve early diagnosis and prognostic prediction and of candidate targets to develop new therapeutic approaches remains of primary importance for this pathology

Optical Characterisation of Hydroxide Catalysed Bonds Applied to Phosphate Glass

We apply the Hydroxide Catalysis Bonding (HCB) technique to phosphate glass and measure the reflectivity and Light Induced Damage Threshold (LITD) of the newly formed interface. HCB is a room temperature, high performing process which was designed for astronomical research glass assemblies and played a key role in the detection of gravitational waves, a breakthrough in contemporary science. The bonds have numerous assets including mechanical strength, stability, no outgassing and resistance to contamination which are of high interest in the precision optics industry. However only little research has been done on their optical properties and mostly on silica based materials. In this paper, we use HCB to bond phosphate glass at room temperature with the goal of designing composite components for solid state laser gain media. We change the solution parameters to identify how they influence the final properties of the bonds: the LIDT at 1535 nm in long pulse regime and the reflectivity at 532 nm are investigated. The measurement of the incidence dependent reflectance allows estimating the thickness and refractive index of the bond in a non destructive process. The best performing set of parameters yields a LIDT of 1.6 GW/cm2 (16 J/cm2) and a reflectivity below 0.03 % which makes it suitable for use in high power lasers. The bond thickness is derived both from Scanning Electron Microscopy and the reflectivity measurements and is in the range of 50-150 nm depending on the parameters. Finally, the bonds survive cutting and polishing which is promising for manufacturing purpose