Searching for chemical inhomogeneities in Open Clusters: Analysis of the CN and CH Molecular Band Strengths in NGC 2158, NGC 2420, NGC 2682, NGC 7789 and Berkeley 29

Context: The total mass of a cluster, being the main parameter determining its ability to host more than one stellar generation, may constitute a threshold below which the cluster is able to form only a single stellar population. AIms: Our goal is to investigate the existence of star-to-star variations of CN and CH band strengths, related to the N and C abundances, respectively, among the stars in five open cluster (NGC 2158, NGC 2420, NGC 2682, NGC 7789 and Berkeley 29) similar to those observed in globular clusters and linked with the existence of multiple populations therein. Since these systems are less massive than globulars, our results may allow us to constrain the lower mass necessary to form more than one stellar population. Methods: We measured the strength of the CN and CH bands, which correlate with the C and N abundances, using four molecular indices in low-resolution SDSS/SEGUE spectra. Results: We found that for four of the open clusters (NGC 2158, NGC 2420, NGC 2682 and Berkeley 29) all the stars studied in each of them have similar CN and CH band strengths within the uncertainties since neither anomalous spreads nor bimodalities have been detected in their CN and CH distributions. In contrast, for NGC 7789 we found an anomalous spread in the strength of the CN molecular band at 3839 \AA which is larger than the uncertainties. However, the small number of stars studied in this cluster implies that further analysis is needed to confirm the existence of chemical inhomogeneities in this cluster.Comment: 11 pages, 9 figures, Accepted for publication in A&A, Tables 7, 8 and 9 will be publish onlin

Strength demands of tall wind turbines subject to earthquakes and wind load

Wind and earthquake load have historically been conceived to act independently. However, if we reflect on the fact that major seismic events are usually followed by a number of aftershocks and that wind is constantly flowing at high intensities around wind farms, which induces additional demands of resistance to infrastructure, then the joint probability of middle-to strong earthquakes and low-to mild wind events becomes more relevant. In this paper a generalised approach is used to estimate the ratio between earthquake and wind forces and their effect on infrastructure. Following, a probabilistic analysis is carried out to show that under certain conditions the combination of these natural events can induce additional demands of strength and ductility to wind turbines which could lead to unforeseen damage

Adopting BIM to Enhance Sustainability. The Saudi Arabia Construction Projects case study

Building information modelling (BIM) has become an efficient tool to contribute more effectively to achieving sustainability development goals. BIM utilities have progressively revealed efficient environments to share data amongst stakeholders. The present paper aims to evaluate levels of awareness around BIM capabilities amongst engineers and project managers, focusing on the Saudi Arabia construction industry. The study targeted individuals registered with the Saudi Council of Engineers until the year 2020, who were invited to engage with a questionnaire survey. The study targeted individuals registered with the Saudi Council of Engineers, who were invited to engage with a questionnaire survey. A sample of 940 participants was taken by the survey out of a total population of the study of 55776 engineers whose responses materialised in a robust statistical analysis. According to the survey, 61% (circa 572) have developed awareness of BIM, whereas 39% (368) confirmed that they had never heard of it. A descriptive Statistics framework with the aid of SPSS has been developed to complete the statistical study. Analyses of data indicated that the benefit of using BIM is significant in the broad sustainability realm, Life Cycle Cost (LCC), operations and maintenance, efficient use of energy, daylight analysis, thermal design, and transparency in cost

Laboratory activity to effectively teach introductory geomicrobiology concepts to non-geology majors

We have designed a three-week experiment that can complement any microbiology course, to teach main geomicrobiology concepts for non-geology majors. One of the most difficult concepts for non-geology majors to comprehend is how bacteria serve as a platform for different mineralization reactions. In our three-week laboratory practice, students learn the main principles and conditions required for an induced bacterial mineralization. Upon completion of the laboratory experience, students will: 1) learn how microbial-induced mineralization (such as calcium carbonate formation) is affected by differential media and growth conditions; 2) understand how bacterial physiology affects any induced in situ or in vitro mineralization; 3) comprehend how growing conditions and bacterial physiologies interrelate, resulting in differential crystal formation. The teaching-learning process was assessed using a pre-/posttest with an increase from 26% to 76% in the number of positive answers from the students. We also measured the students' proficiency while conducting specific technical tasks, revealing no major difficulties while conducting the experiments. A final questionnaire was provided with satisfactory evaluations from the students regarding the organization and content of the practices. 84-86% of the students agreed that the exercises improved their knowledge in geomicrobiology and would like to attend similar laboratories in the future. Such response is the best indicator that the laboratory practice can be implemented in any undergraduate/graduate microbiology course to effectively teach basic geomicrobiology concepts to non-geology majors

On the structural response of a tall hybrid onshore wind turbine tower

Given the increasing demand for taller structures in wind energy applications and the accompanying need for a better understanding of their structural response, the present study performs aeroelastic analysis on a novel wind turbine structure and discusses the obtained results. The response of a hybrid onshore wind turbine tower consisting of a 60 m lattice structure and a 60 m tapered tubular structure, with a 5 MW class AII turbine, is investigated. From the Design Load Cases (DLC) established in IEC64100-1 standard, focus is set on DLC 1.1 and DLC 1.3 which correspond to power production conditions and embody the requirements for loads resulting from atmospheric turbulence during normal and extreme operating conditions respectively. DLC 6.1 which refers to standstill or idling conditions under extreme wind model is also studied. In order to account for the interaction between elastic, viscous and inertial forces of the structure and the external aerodynamic forces, ashes, an integrated analysis software, is used. After developing the wind turbine tower model and generating the turbulence models, 600 seconds simulations are performed. The wind flow is assumed to be parallel to the hub axis. For DLC 1.1 and DLC 1.3, parametric studies with the wind speed ranging from 3 to 25 m/s, with an incremental step of 1 m/s, are executed. In DLC 6.1, the blades are feathered and the wind speed is rapidly increased to 42.5 m/s. Time histories of the elemental forces and the nodal displacements are extracted in critical positions of both the lattice and the tubular part. The mean values of the output data are evaluated and plotted against the wind speed. Conclusions regarding the influence of the wind speed on the induced tower behaviour are drawn

Effects of Acid Mine Drainage on the Release of Aluminum from Clay Minerals

The objective of this PhD research was to investigate the leaching of acid clays with acid mine/rock drainages (AMD/ARD) typically found in U.S. soils and develop information supporting the phenomena of the release of elevated concentrations of aluminum from such interactions. In Pennsylvania, reported aluminum concentrations in discharge samples from 140 abandoned coal mines showed that over 50% of these water samples presented dissolved aluminum concentrations over 1 mg/L. Aluminum at these levels can be detrimental to freshwater aquatic ecosystems and thus, these data suggest that aluminum-containing AMD/ARD is a major problem in USA. Leaching of smectite clays with different synthetic AMD/ARD were conducted to explore the effect of common cations in pyritic and brackish/saline AMD/ARD, on the release of aluminum from clays at pH between 2 and 3 frequently found in the field. The major finding of this research is that the release of aluminum from smectite clays is enhanced by Fe2+, potassium (KCl) and sodium (NaCl) salts in AMD/ARD. The major mechanisms involved in the release of aluminum from these clays were: cation-exchange dominating the short-term and clay dissolution dominating the long-term leaching of aluminum from smectites. These results were consistent with the low iron concentrations and high aluminum concentrations observed in some field AMD/ARD.The outcome of this research adds new knowledge to the field of environmental science and engineering by pointing out the significant effects that K and Na salts in AMD/ARD have on the release of aluminum from clays. These K and Na salts in AMD/ARD promote the release of Al from field clays leading to deleterious effects on aquatic ecosystems. Thus, this research contributes to a better understanding of the occurrence of elevated levels of aluminum in AMD/ARD and will assist others to consider alternative remediation strategies in those locations where the in situ generation of high concentration of aluminum discharges may occur. The observation of greater concentrations of aluminum in leachate produced by brackish AMD/ARD implies that highway deicing salts in road runoff could aggravate the leaching of aluminum from pyritic rocks used as fill or exposed in road cuts

Characterization of femtosecond laser written waveguides for integrated biochemical sensing

Fluorescence detection is known to be one of the most sensitive among the different optical sensing techniques. This work focuses on excitation and detection of fluorescence emitted by DNA strands labeled with fluorescent dye molecules that can be excited at a specific wavelength. Excitation occurs via optical channel waveguides written with femtosecond laser pulses applied coplanar with a microfluidic channel on a glass chip. The waveguides are optically characterized in order to facilitate the design of sensing structures which can be applied for monitoring the spatial separation of biochemical\ud species as a result of capillary electrophoresis

Fluorescence monitoring of capilarry electrophoresis separation in a lab-on-a-chip with monolithically integrated waveguides

Femtosecond-laser-written optical waveguides were monolithically integrated into a commercial lab-on-a-chip to intersect a microfluidic channel. Laser excitation through these waveguides confines the excitation window to a width of 12 μm, enabling high-spatial-resolution monitoring of different fluorescent analytes, during their migration/separation in the microfluidic channel by capillary electrophoresis. Wavelength-selective monitoring of the on-chip separation of fluorescent dyes is implemented as a proof-of-principle. We envision well-controlled microfluidic plug formation, waveguide excitation, and a low limit of detection to enable monitoring of extremely small quantities with high spatial resolution

Multi-color fluorescent DNA analysis in an integrated optofluidic lab-on-a-chip

Sorting and sizing of DNA molecules within the human genome project has enabled the genetic mapping of various illnesses. By employing tiny lab-on-a-chip devices for such DNA analysis, integrated DNA sequencing and genetic diagnostics have become feasible. However, such diagnostic chips typically lack integrated sensing capability. We address this issue by combining microfluidic capillary electrophoresis with laser-induced fluorescence detection resulting in optofluidic integration towards an on-chip bio-analysis tool [1,2]. We achieve a spatial separation resolution of 12 μm, which can enable a 20-fold enhancement in electropherogram peak resolution, leading to plate numbers exceeding one million. We demonstrate a high sizing/calibration accuracy of 99% [3], and ultrasensitive fluorescence detection (limit of detection = 65 femtomolar, corresponding to merely 2-3 molecules in the excitation/detection volume) of diagnostically relevant double-stranded DNA molecules by integrated-waveguide laser excitation. Subsequently, we introduce a principle of parallel optical processing to this optofluidic lab-on-a-chip. Different sets of exclusively color-labeled DNA fragments – otherwise rendered indistinguishable by their spatio-temporal coincidence – are traced back to their origin by modulation-frequency-encoded multi-wavelength laser excitation, fluorescence detection with a color-blind photomultiplier, and Fourier-analysis decoding. As a proof of principle, fragments from independent human genomic segments, associated with genetic predispositions to breast cancer and anemia, are extracted by multiplex ligation-dependent probe amplification, and simultaneously analyzed. Such multiple yet unambiguous optical identification of biomolecules opens new horizons for “enlightened” lab-on-a-chip devices