98 research outputs found
Many ways to make darker flies: Intra-and interspecific variation in Drosophila body pigmentation components
Body pigmentation is an evolutionarily diversified and ecologically relevant trait with
substantial variation within and between species, and important roles in animal survival
and reproduction. Insect pigmentation, in particular, provides some of the most
compelling examples of adaptive evolution, including its ecological significance and
genetic bases. Pigmentation includes multiple aspects of color and color pattern that
may vary more or less independently, and can be under different selective pressures.
We decompose Drosophila thorax and abdominal pigmentation, a valuable eco-evo-
devo
model, into distinct measurable traits related to color and color pattern. We
investigate intra-and
interspecific variation for those traits and assess its different
sources. For each body part, we measured overall darkness, as well as four other
pigmentation properties distinguishing between background color and color of the
darker pattern elements that decorate each body part. By focusing on two standard
D. melanogaster laboratory populations, we show that pigmentation components
vary and covary in distinct manners depending on sex, genetic background, and temperature
during development. Studying three natural populations of D. melanogaster
along a latitudinal cline and five other Drosophila species, we then show t hat evolution
of lighter or darker bodies can be achieved by changing distinct component
traits. Our results paint a much more complex picture of body pigmentation variation
than previous studies could uncover, including patterns of sexual dimorphism,
thermal plasticity, and interspecific diversity. These findings underscore the value of
detailed quantitative phenotyping and analysis of different sources of variation for a
better understanding of phenotypic variation and diversification, and the ecological
pressures and genetic mechanisms underlying them.info:eu-repo/semantics/publishedVersio
Fabrication of thin diamond membranes by Ne implantation
Color centers in diamond are one of the most promising tools for quantum
information science. Of particular interest is the use of single-crystal
diamond membranes with nanoscale-thickness as hosts for color centers. Indeed,
such structures guarantee a better integration with a variety of other quantum
materials or devices, which can aid the development of diamond-based quantum
technologies, from nanophotonics to quantum sensing. A common approach for
membrane production is what is known as "smart-cut", a process where membranes
are exfoliated from a diamond substrate after the creation of a thin
sub-surface amorphous carbon layer by He implantation. Due to the high ion
fluence required, this process can be time-consuming. In this work, we
demonstrated the production of thin diamond membranes by neon implantation of
diamond substrates. With the target of obtaining membranes of 200 nm
thickness and finding the critical damage threshold, we implanted different
diamonds with 300 keV Ne ions at different fluences. We characterized the
structural properties of the implanted diamonds and the resulting membranes
through SEM, Raman spectroscopy, and photoluminescence spectroscopy. We also
found that a SRIM model based on a two-layer diamond/sp-carbon target
better describes ion implantation, allowing us to estimate the diamond critical
damage threshold for Ne implantation. Compared to He smart-cut, the use
of a heavier ion like Ne results in a ten-fold decrease in the ion fluence
required to obtain diamond membranes and allows to obtain shallower smart-cuts,
i.e. thinner membranes, at the same ion energy
Basin-scale gyres and mesoscale eddies in large lakes: a novel procedure for their detection and characterization, assessed in Lake Geneva
In large lakes subject to the Coriolis force, basin-scale
gyres and mesoscale eddies, i.e. rotating coherent water masses, play a key
role in spreading biochemical materials and energy throughout the lake. In
order to assess the spatial and temporal extent of gyres and eddies, their
dynamics and vertical structure, as well as to validate their prediction in
numerical simulation results, detailed transect field observations are
needed. However, at present it is difficult to forecast when and where such
transect field observations should be taken. To overcome this problem, a
novel procedure combining 3D numerical simulations, statistical analyses,
and remote sensing data was developed that permits determination of the
spatial and temporal patterns of basin-scale gyres during different seasons.
The proposed gyre identification procedure consists of four steps: (i) data
pre-processing, (ii) extracting dominant patterns using empirical orthogonal
function (EOF) analysis of Okubo–Weiss parameter fields, (iii) defining the
3D structure of the gyre, and (iv) finding the correlation between the
dominant gyre pattern and environmental forcing. The efficiency and
robustness of the proposed procedure was validated in Lake Geneva. For the
first time in a lake, detailed field evidence of the existence of
basin-scale gyres and (sub)mesoscale eddies was provided by data collected
along transects whose locations were predetermined by the proposed
procedure. The close correspondence between field observations and detailed
numerical results further confirmed the validity of the model for capturing
large-scale current circulations as well as (sub)mesoscale eddies. The
results also indicated that the horizontal gyre motion is mainly determined
by wind stress, whereas the vertical current structure, which is influenced
by the gyre flow field, primarily depends on thermocline depth and strength.
The procedure can be applied to other large lakes and can be extended to the
interaction of biological–chemical–physical processes.</p
Allograft or autograft in skeletally immature anterior cruciate ligament reconstruction: A prospective evaluation using both partial and complete transphyseal techniques
Objective: We compared autografts and allograft using partial and complete transphyseal anterior cruciate ligament (ACL) reconstruction techniques among skeletally immature individuals. Methods: Male and females younger than 18 and 16 years old, respectively, diagnosed with ACL tear from April 2006 to March 2012 entered the study. One group had four-strand hamstring autograft, and the other had tibialis posterior allograft reconstruction. Those who had allografts either had hyper-laxity or recurvatum. Results: Achieved mean (± SD) 2000 International Knee Documentation Committee subjective score was not statistically different (P = 0.385) between allograft (n = 13) (84.3 ± 3.2) and autograft groups (n = 18) (85.6 ± 4.4). Mean Knee injury and Osteoarthritis Outcome Score (KOOS) subscale Knee-Related Quality of Life at 2 years was 78.0 ± 7.2 and 75 ± 7.4 for allograft and autograft groups, respectively (p = 0.261). Mean 2-year KOOS subscale Sports and Recreation was 82.1 ± 5.8 and 84.8 ± 6.6 for allograft and autograft groups, respectively (p = 0.244). No patient reported instability, giving way, or locking of the knee. Pivot shift test was negative in all patients; however, a minor positive Lachman test was found in six cases (46) within the allograft group and seven cases (39) in the autograft group. One postoperative septic arthritis was documented in the autograft group. Conclusion: Considering existing concern that joint laxity and recurvatum are among the precursors of non-contact ACL injury in adolescents, bone-patellar-bone autografts are not applicable in this age group because of the open physis; furthermore, considering that hamstring autografts are insufficient (size thickness and stretchability), we recommend soft tissue allografts for ACL reconstruction in skeletally immature patients. © 2019 The Author(s)
A New Image Analysis Based Method for Measuring Electrospun Nanofiber Diameter
In this paper, a new image analysis based method for electrospun nanofiber diameter measurement has been presented. The method was tested by a simulated image with known characteristics and a real web. Mean (M) and standard deviation (STD) of fiber diameter obtained using this method for the simulated image were 15.02 and 4.80 pixels respectively, compared to the true values of 15.35 and 4.47 pixels. For the real web, applying the method resulted in M and STD of 324 and 50.4 nm which are extremely close to the values of 319 and 42 nm obtained using manual method. The results show that this approach is successful in making fast, accurate automated measurements of electrospun fiber diameters
Electro-plating and characterisation of cadmium sulphide thin films using ammonium thiosulphate as the sulphur source
Cadmium sulphide (CdS) thin films have been successfully prepared from an aqueous electrolyte bath containing CdCl2 and ammonium thiosulphate ((NH4)2S2O3) using electrodeposition technique. The structural, compositional, optical, morphological and electrical properties of these thin films have been characterized using X-ray diffraction (XRD), Raman spectroscopy, energy dispersive X-ray spectroscopy, UV–Vis spectrophotometry, scanning electron microscopy (SEM), atomic force microscopy (AFM), photoelectrochemical cell and D.C. current–voltage (I–V) measurements. The optimum deposition cathodic potential has been observed at 1,455 mV, in a 2-electrode system with respect to carbon anode. Structural analysis using XRD shows a mixture of hexagonal and cubic phases in the as-deposited CdS samples and a phase transformation to the hexagonal structure occurred after heat treatment at 400 °C for 20 min. Optical studies demonstrate an improvement in the band edge, producing 2.42 eV for the band gap of the films after heat treatment. The heat treated CdS thin films show better transmission for wavelengths longer than 500 nm. SEM and AFM show that the heat-treated samples are more uniform, smoother and have larger grain size. Electrical studies confirm that the CdS thin films have n-type electrical conductivity and heat treated CdS thin films have resistivities of the order of 105 Ω cm
Effects of deposition time and post-deposition annealing on the physical and chemical properties of electrodeposited CdS thin films for solar cell application
CdS thin films were cathodically electrodeposited by means of a two-electrode deposition system
for different durations. The films were characterised for their structural, optical, morphological
and compositional properties using x-ray diffraction (XRD), spectrophotometry, scanning
electron microscopy (SEM) and energy dispersive x-ray (EDX) respectively. The results obtained
show that the physical and chemical properties of these films are significantly influenced by the
deposition time and post-deposition annealing. This influence manifests more in the as-deposited
materials than in the annealed ones. XRD results show that the crystallite sizes of the different
films are in the range (9.4 – 65.8) nm and (16.4 – 66.0) nm in the as-deposited and annealed
forms respectively. Optical measurements show that the absorption coefficients are in the range
(2.7×104 – 6.7×104) cm-1 and (4.3×104 – 7.2×104) cm-1 respectively for as-deposited and annealed
films. The refractive index is in the range (2.40 – 2.60) for as-deposited films and come to the
value of 2.37 after annealing. The extinction coefficient varies in the range (0.1 – 0.3) in asdeposited
films and becomes 0.1 in annealed films. The estimated energy bandgap of the films is
in the range (2.48 – 2.50) eV for as-deposited films and becomes 2.42 eV for all annealed films.
EDX results show that all the films are S-rich in chemical composition with fairly uniform Cd/S
ratio after annealing. The results show that annealing improves the qualities of the films and
deposition time can be used to control the film thickness.
Keywords: Electrodeposition; two-electrode system; CdS; annealing; deposition time; thin-film
Magnetized Chitosan Hydrogel and Silk Fibroin, Reinforced with PVA: A Novel Nanobiocomposite for Biomedical and Hyperthermia Applications
Herein, a multifunctional nanobiocomposite was designed for biological application, amongst which hyperthermia cancer therapy application was specifically investigated. This nanobiocomposite was fabricated based on chitosan hydrogel (CS), silk fibroin (SF), water-soluble polymer polyvinyl alcohol (PVA) and iron oxide magnetic nanoparticles (Fe3O4 MNPs). CS and SF as natural compounds were used to improve the biocompatibility, biodegradability, adhesion and cell growth properties of the nanobiocomposite that can prepare this nanocomposite for the other biological applications such as wound healing and tissue engineering. Since the mechanical properties are very important in biological applications, PVA polymer was used to increase the mechanical properties of the prepared nanobiocomposite. All components of this nanobiocomposite have good dispersion in water due to the presence of hydrophilic groups such as NH2, OH, and COOH, which is one of the effective factors in increasing the efficiency of hyperthermia cancer therapy. The structural analyzes of the hybrid nanobiocomposite were determined by FT-IR, XRD, EDX, FE-SEM, TGA and VSM. Biological studies such as MTT and hemolysis testing proved that it is hemocompatible and non-toxic for healthy cells. Furthermore, it can cause the death of cancer cells to some extent (20.23%). The ability of the nanobiocomposites in hyperthermia cancer therapy was evaluated. Also, the results showed that it can be introduced as an excellent candidate for hyperthermia cancer therapy
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