1,639 research outputs found
Rhodococcus aetherivorans BCP1 as cell factory for the production of intracellular tellurium nanorods under aerobic conditions
Background: Tellurite (TeO32-) is recognized as a toxic oxyanion to living organisms. However, mainly anaerobic or facultative-anaerobic microorganisms are able to tolerate and convert TeO32- into the less toxic and available form of elemental Tellurium (Te0), producing Te-deposits or Te-nanostructures. The use of TeO32--reducing bacteria can lead to the decontamination of polluted environments and the development of "green-synthesis" methods for the production of nanomaterials. In this study, the tolerance and the consumption of TeO32- have been investigated, along with the production and characterization of Te-nanorods by Rhodococcus aetherivorans BCP1 grown under aerobic conditions. Results: Aerobically grown BCP1 cells showed high tolerance towards TeO32- with a minimal inhibitory concentration (MIC) of 2800ÎŒg/mL (11.2mM). TeO32- consumption has been evaluated exposing the BCP1 strain to either 100 or 500ÎŒg/mL of K2TeO3 (unconditioned growth) or after re-inoculation in fresh medium with new addition of K2TeO3 (conditioned growth). A complete consumption of TeO32- at 100ÎŒg/mL was observed under both growth conditions, although conditioned cells showed higher consumption rate. Unconditioned and conditioned BCP1 cells partially consumed TeO32- at 500ÎŒg/mL. However, a greater TeO32- consumption was observed with conditioned cells. The production of intracellular, not aggregated and rod-shaped Te-nanostructures (TeNRs) was observed as a consequence of TeO32- reduction. Extracted TeNRs appear to be embedded in an organic surrounding material, as suggested by the chemical-physical characterization. Moreover, we observed longer TeNRs depending on either the concentration of precursor (100 or 500ÎŒg/mL of K2TeO3) or the growth conditions (unconditioned or conditioned grown cells). Conclusions:Rhodococcus aetherivorans BCP1 is able to tolerate high concentrations of TeO32- during its growth under aerobic conditions. Moreover, compared to unconditioned BCP1 cells, TeO32- conditioned cells showed a higher oxyanion consumption rate (for 100ÎŒg/mL of K2TeO3) or to consume greater amount of TeO32- (for 500ÎŒg/mL of K2TeO3). TeO32- consumption by BCP1 cells led to the production of intracellular and not aggregated TeNRs embedded in an organic surrounding material. The high resistance of BCP1 to TeO32- along with its ability to produce Te-nanostructures supports the application of this microorganism as a possible eco-friendly nanofactory
A haptic-enabled multimodal interface for the planning of hip arthroplasty
Multimodal environments help fuse a diverse range of sensory modalities, which is particularly important when integrating the complex data involved in surgical preoperative planning. The authors apply a multimodal interface for preoperative planning of hip arthroplasty with a user interface that integrates immersive stereo displays and haptic modalities. This article overviews this multimodal application framework and discusses the benefits of incorporating the haptic modality in this area
Planetâsun sensor revisited
Since the seminal work of Daniele Mortari (âMoon-Sun Attitude Sensor,â Journal of Spacecraft and Rockets, Vol. 34, No. 3, 1997, pp. 360â364), the concept of an attitude sensor using images of illuminated celestial bodies has been pushed forward through the years. The basic idea consists of extracting two independent directions from the image of a celestial body, namely, the camera-to-planet and the planet-to-sun directions. The former is estimated from the center of an ellipse fitted to the imaged limb points and the latter from the symmetry axis of the illuminated region. These assumptions, however, only hold for far-distant spherical targets. In this work, the problem is reformulated in the framework of projective camera transformations of quadrics and conics, and an algorithm estimating the line of sight to the planet and the illumination direction from the limb and terminator ellipses, respectively, is presented. The method is applicable to any ellipsoidlike celestial body having known orientation. The algorithm is first validated on synthetically generated images and then tested using real pictures of Dione and Enceladus satellites gathered from Cassini spacecraft. Results show that the sensor concept returns rms errors in the order of the angular width of a pixel in computing the nadir direction, and subdegree accuracy in computing the sun direction
Assembly, growth and conductive properties of tellurium nanorods produced by Rhodococcus aetherivorans BCP1
Tellurite (TeO32-) is a hazardous and toxic oxyanion for living organisms. However, several microorganisms can bioconvert TeO32- into the less toxic form of elemental tellurium (Te0). Here, Rhodococcus aetherivorans BCP1 resting (non-growing) cells showed the proficiency to produce tellurium-based nanoparticles (NPs) and nanorods (NRs) through the bioconversion of TeO32-, depending on the oxyanion initial concentration and time of cellular incubation. Te-nanostructures initially appeared in the cytoplasm of BCP1 cells as spherical NPs, which, as the exposure time increased, were converted into NRs. This observation suggested the existence of an intracellular mechanism of TeNRs assembly and growth that resembled the chemical surfactant-assisted process for NRs synthesis. The TeNRs produced by the BCP1 strain showed an average length (>700 nm) almost doubled compared to those observed in other studies. Further, the biogenic TeNRs displayed a regular single-crystalline structure typically obtained for those chemically synthesized. The chemical-physical characterization of the biogenic TeNRs reflected their thermodynamic stability that is likely derived from amphiphilic biomolecules present in the organic layer surrounding the NRs. Finally, the biogenic TeNRs extract showed good electrical conductivity. Thus, these findings support the suitability of this strain as eco-friendly biocatalyst to produce high quality tellurium-based nanomaterials exploitable for technological purposes
DISPLAYING DANTEâS DIVINE COMEDY MINIATED MANUSCRIPTS IN EXHIBITIONS
Ancient manuscripts are part of many collections belonging to historic libraries and museums: due to their fragile nature and to the difficulties to display most of their contents during exhibitions, their study is often complicated for scholars who also need generally special permissions to examine them, mostly for a limited time window. Beginning from these premises, this paper introduces the outcomes of the digital replication and presentation of three manuscripts related to Danteâs Divine Comedy, as proposed on a real exhibition, âDallâAlma Mater al Mondo. Dante at the University of Bolognaâ, held in 2021. Some of the principles related to the production of their replicas and the fruition of their contents through dedicated applications targeted to visitors and scholars are presented, with care to the reproduction of details such as the ability to explore 3D replicas of detailed elected pages or to browse many of them on dedicated touch screens
A dual output polarimeter devoted to the study of the Cosmic Microwave Background
We have developed a correlation radiometer at 33 GHz devoted to the search
for residual polarization of the Cosmic Microwave Background (CMB). The two
instruments`s outputs are linear combination of two Stokes Parameters (Q and U
or U and V). The instrument is therefore directly sensitive to the polarized
component of the radiation (respectively linear and circular). The radiometer
has a beam-width oif 7 or 14 deg, but it can be coupled to a telescope
increasing the resolution. The expected CMB polarization is at most a part per
milion. The polarimeter has been designed to be sensitive to this faint signal,
and it has been optimized to improve its long term stability, observing from
the ground. In this contribution the performances of the instrument are
presented, together with the preliminary test and observations.Comment: 12 pages, 6 figures, in print on the Proc. SPIE Conf. - August 200
The Use of Fura-2 Fluorescence to Monitor the Movement of Free Calcium Ions into the Matrix of Plant Mitochondria (Pisum sativum and Helianthus tuberosus)
Direct and Heterodyne Detection of Microwaves in a Metallic Single Wall Carbon Nanotube
This letter reports measurements of microwave (up to 4.5 GHz) detection in
metallic single-walled carbon nanotubes. The measured voltage responsivity was
found to be 114 V/W at 77K. We also demonstrated heterodyne detection at 1 GHz.
The detection mechanism can be explained based on standard microwave detector
theory and the nonlinearity of the DC IV-curve. We discuss the possible causes
of this nonlinearity. While the frequency response is limited by circuit
parasitics in this measurement, we discuss evidence that indicates that the
effect is much faster and that applications of carbon nanotubes as terahertz
detectors are feasible
Growth of Rhodococcus sp. strain BCP1 on gaseous n-alkanes: New metabolic insights and transcriptional analysis of two soluble di-iron monooxygenase genes
Rhodococcus sp. strain BCP1 was initially isolated for its ability to grow on gaseous n-alkanes, which act as inducers for the co-metabolic degradation of low-chlorinated compounds. Here, both molecular and metabolic features of BCP1 cells grown on gaseous and short-chain n-alkanes (up to n-heptane) were examined in detail. We show that propane metabolism generated terminal and sub-terminal oxidation products such as 1- and 2-propanol, whereas 1-butanol was the only terminal oxidation product detected from n-butane metabolism. Two gene clusters, prmABCD and smoABCD-coding for Soluble Di-Iron Monooxgenases (SDIMOs) involved in gaseous n-alkanes oxidation-were detected in the BCP1 genome. By means of Reverse Transcriptase-quantitative PCR (RT-qPCR) analysis, a set of substrates inducing the expression of the sdimo genes in BCP1 were assessed as well as their transcriptional repression in the presence of sugars, organic acids, or during the cell growth on rich medium (Luria-Bertani broth). The transcriptional start sites of both the sdimo gene clusters were identified by means of primer extension experiments. Finally, proteomic studies revealed changes in the protein pattern induced by growth on gaseous- (n-butane) and/or liquid (n-hexane) short-chain n-alkanes as compared to growth on succinate. Among the differently expressed protein spots, two chaperonins and an isocytrate lyase were identified along with oxidoreductases involved in oxidation reactions downstream of the initial monooxygenase reaction step
Orientational order parameters of a de Vriesâtype ferroelectric liquid crystal obtained by polarized Raman spectroscopy and x-ray diffraction
The orientational order parameters â©P2âȘ and â©P4âȘ of the ferroelectric, de Vriesâtype liquid crystal 9HL have been determined in the SmA* and SmC* phases by means of polarized Raman spectroscopy, and in the SmA* phase using x-ray diffraction. Quantum density functional theory predicts Raman spectra for 9HL that are in good agreement with the observations and indicates that the strong Raman band probed in the experiment corresponds to the uniaxial, coupled vibration of the three phenyl rings along the molecular long axis. The magnitudes of the orientational order parameters obtained in the Raman and x-ray experiments differ dramatically from each other, a discrepancy that is resolved by considering that the two techniques probe the orientational distributions of different molecular axes. We have developed a systematic procedure in which we calculate the angle between these axes and rescale the orientational order parameters obtained from x-ray scattering with results that are then in good agreement with the Raman data. At least in the case of 9HL, the results obtained by both techniques support a âsugar loafâ orientational distribution in the SmA* phase with no qualitative difference to conventional smectics A. The role of individual molecular fragments in promoting de Vriesâtype behavior is considered
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