461 research outputs found
On the preparation and characterization of thin NiTi shape memory alloy wires for MEMS
Get PDFShape memory alloy (SMA) wires are employed as actuators in small devices for consumer electronics, valves and automotive applications. Because of the continued miniaturization of all the industrial products, nowadays the tendency is to produce MEMS (micro electromechanical systems). Among the most promising functional MEMS materials, the thin SMA wires that are offering a rapid actuating response with high power/weigh ratio of the material, are attracting a world wide interest. This paper is aimed at showing the production process and the characterizations of thin NiTi shape memory wires. The activity was focused on drawing procedure and on functional and TEM characterizations of the final products. In particular, it was evaluated the performance of the SMA wires for actuators in terms of functional fatigue and thermo-mechanical properties by means of an experimental apparatus design ad hoc for these specific tests
MRI guided magneto-chemotherapy with high-magnetic-moment iron oxide nanoparticles for cancer theranostics
No full textElevating and monitoring the temperature of tumors using magnetic nanoparticles (MNPs) still presents a challenge in magnetic hyperthermia therapy. The efficient heating of tumor volume can be achieved by preparing MNPs with high magnetization values. The next-generation approach to magnetic resonance image (MRI)-guided magneto-chemotherapy of cancer based on high-magnetic-moment iron oxide nanoparticles is proposed. The proof of concept is validated by cellular MRI experiments on breast cancer cells. To explore magneto-chemotherapy, we developed high-magnetic-moment iron oxide (Fe3O4) nanoparticles (NPs) using base diisopropylamine (DIPA), which plays a dual role as reducing agent and surface stabilizer. Spherical NPs with ∼12 nm size and a high magnetization value of about 92 emu g–1 at room temperature are obtained by this unique method. A high specific absorption rate value of ∼717 wg–1 was obtained for Fe3O4 NPs in water at an alternating magnetic field of 20 kAm–1 and frequency of 267 kHz, which is attributed to the high magnetization value. The magneto-polymeric micelle structure is formed by using Pluronic F127, and anticancer drug doxorubicin is conjugated in the micelle by electrostatic interactions for magneto-chemotherapy. Finally, the magnetic resonance imaging (MRI)-guided magneto-chemotherapy was achieved on breast cancer (MCF7) cells with an overall ∼96% killing of cancer cells attained in 30 min of magneto-chmeotherapy
Multiple approach to test nano TiO2 photo-activity
No full textOne of the most important applications of nanostructured TiO2 is the manufacture of self-cleaning textiles. It is believed that the self-cleaning properties originate from the photocatalysis of water by nanostructured TiO2, but the mechanisms acting on textiles, and particularly the phenomena occurring at the interface, are not fully understood yet. A comparative study is proposed here to investigate the photo-catalytic activity and the efficiency of modified TiO2 nanomaterials with the purpose to identify the mostsuitable analytical method to probe photocatalysis in self-cleaning textiles. The present study sets upreliable, robust, fast and low-cost tests and compares them using TiO2/SiO2nanocomposite systems withdifferent SiO2contents. The photocatalytic activity and efficiency of these nanocomposites were bench-marked by three different experimental protocols: a recently developed electrochemical technique todetermine hydroxyl radicals (•OH) and two well-known methods, namely trapping of•OH radicals bysalicylic acid and degradation of Rhodamine B dye due to photocatalytic actions. The results suggest that the photoactivity of TiO2incorporated in textiles is mainly related to a direct reactivity of the surface oxidizing carriers toward the organic target molecule. The salicylic acid and Rhodamine B test provide mutually consistent results drawing similar trends of the photocatalytic performance. The electrochemical method turns to be a valid alternative when photocatalytic reactivity is driven by•OH radicals diffusedin a liquid medium. For self-cleaning textile applications, the salicylic acid test provides a more reliable quantitative prediction of the photocatalytic activity, while the Rhodamine B test represents a robust qualitative indicator
Impact and effectiveness of risk mitigation strategies on the insurability of nanomaterial production: evidences from industrial case studies
No full textWorkers involved in producing nanomaterials or using nanomaterials in manufacturing plants are likely to have earlier and higher exposure to manufactured/engineered nanomaterials (ENM) than the general population. This is because both the volume handled and the probability of the effluence of 'free' nanoparticles from the handled volume are much higher during a production process than at any other stage in the lifecycle of nanomaterials and nanotechnology-enabled products. Risk assessment (RA) techniques using control banding (CB) as a framework for risk transfer represents a robust theory but further progress on implementing the model is required so that risk can be transferred to insurance companies. Following a review of RA in general and hazard measurement in particular, we subject a Structural Alert Scheme methodology to three industrial case studies using ZrO2, TiO2, and multi-walled carbon nanotubes (MWCNT). The materials are tested in a pristine state and in a remediated (coated) state, and the respective emission and hazard rates are tested alongside the material performance as originally designed. To our knowledge, this is the first such implementation of a CB RA in conjunction with an ENM performance test and offers both manufacturers and underwriters an insight into future applications
Hydraulic simulations to evaluate and predict design and operation of the Chashma Right Bank Canal
Get PDFIrrigation systems / Irrigation canals / Flow control / Velocity / Canal regulation techniques / Hydraulics / Simulation models / Design / Operations / Crop-based irrigation / Distributary canals / Water delivery / Policy / Protective irrigation / Water allocation / Water requirements / Sedimentation / Water distribution / Equity / Water conveyance / Pakistan / Chashma Right Bank Canal
Silica modification of titania nanoparticles enhances photocatalytic production of reactive oxygen species without increasing toxicity potential in vitro
Get PDFTitania (TiO2) nanoparticles were surfacemodified using silica and citrate to implement a ‘safe-by-design’
approach for managing potential toxicity of titania nanoparticles by controlling surface redox reactivity.
DLS and zeta-potential analyses confirmed the surface modification, and electron microscopy and
surface area measurements demonstrated nanoscale dimensions of the particles. Electron
paramagnetic resonance (EPR) was used to determine the exogenous generation of reactive oxygen
species (ROS). All the produced spray dried nanotitania lowered levels of ROS when compared to the
corresponding dispersed nanotitania, suggesting that the spray drying process is an appropriate design
strategy for the control of nano TiO2 ROS reactivity. The modification of nanotitania with silica and
with citrate resulted in increased levels of ROS generation in exogenous measurements, including
photoexcitation for 60 minutes. The dichlorodihydrofluorescein (DCFH) assay of dose-dependent
production of oxidative stress, generated by pristine and modified nanotitania in macrophages and
alveolar epithelial cells, found no significant change in toxicity originating from the generation of
reactive oxygen species. Our findings show that there is no direct correlation between the
photocatalytic activity of nanotitania and its oxidative stress-mediated potential toxicity, and it is
possible to improve the former, for example adding silica as a modifying agent, without altering the
cell redox equilibrium
Mediapipe based Preprocessed VGGFace2 Dataset
No full textVGGFace2 Dataset and Face Mesh PreprocessingIntroductionThe VGGFace2 dataset is a large-scale face recognition dataset containing over 3.31 million images of 9,131 identities, with an average of 362 images per identity. The dataset is designed to include extensive variations in pose, age, illumination, ethnicity, and profession, making it one of the most diverse and challenging face recognition datasets available. For more details, please refer to the original publication:VGGFace2: A dataset for recognizing faces across pose and age - DOI: 10.48550/arXiv.1710.08092
Preprocessing Using MediaPipe 3D Face MeshOn this dataset, we applied the MediaPipe-based 3D face mesh algorithm to accurately detect faces while removing all background elements, including hair. Our preprocessing strictly retained facial landmarks, ensuring that only the essential facial features were preserved. This approach significantly enhanced the accuracy and generalization of our model, as the model was trained exclusively on landmark-based facial data.
Training and PerformanceThe preprocessed data was utilized to train Xception model, which resulted in remarkably accurate outcomes due to the strictly landmark-based facial representation. The model demonstrated robust performance including explainable-AI, proving that eliminating unnecessary background elements contributed positively to its efficiency and reliability.
CitationIf you use this dataset or the preprocessed version in your work, please cite both of the following:
VGGFace2 Dataset:
@article{Cao2018VGGFace2, title={VGGFace2: A dataset for recognizing faces across pose and age}, author={Cao, Qiong and Shen, Li and Xie, Weidi and Parkhi, Omkar M and Zisserman, Andrew}, journal={arXiv preprint arXiv:1710.08092}, year={2018}}
DOI: [10.48550/arXiv.1710.08092](https://doi.org/10.48550/arXiv.1710.08092) Preprocessed Dataset using MediaPipe:@dataset{Shah2025_MediaPipe_FaceMesh, title={MediaPipe-based 3D Face Mesh Preprocessed VGGFace2 Dataset}, author={Shah, Syed Taimoor Hussain and Shah, Syed Adil Hussain and Zamir, Ammara and Qayyum, Kainat and Shah, Syed Baqir Hussain and Fatima, Syeda Maryam and Deriu, Marco Agostino}, year={2025}, doi={10.5281/zenodo.15078557}} DOI: [10.5281/zenodo.15078557](https://doi.org/10.5281/zenodo.15078557)
ContactFor any questions or further details, please feel free to contact us.Syed Taimoor Hussain ShahPolitoBIOMed Lab, Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, ItalyEmail: [email protected]: 0000-0002-6010-677
Comparison of the acute-phase response after laparoscopic versus open aortobifemoral bypass surgery: a substudy of a randomized controlled trial [Erratum]
No full textKrog AH, Sahba M, Pettersen EM, et al. Vasc Health Risk Manag. 2016;12:371–378.On page 371, author list, the author “Syed SS Kazmi” should have read “Syed SH Kazmi”.Read the original articl
Far-Field Subdiffraction Imaging of Semiconductors Using Nonlinear Transient Absorption Differential Microscopy
No full textLabel-free
absorption spectroscopies
are frontline techniques to
reveal the spectral fingerprint, composition and environment of materials
and are applicable to a wide range of samples. In an effort to improve
the spatial resolution of far-field absorption microscopy, which is
limited by the diffraction of light, an imaging technique based on
transient absorption saturation has recently been developed. Here
we report a far-field transient absorption microscopy that does not
require the sample to exhibit saturable absorption to break the diffraction
barrier. By alternating the wavefront of the pump beams and exploiting
a nonlinearity in the transient absorption intrinsic to semiconductors,
we demonstrate imaging, beyond the diffraction limit, in CdSe nanobelts.
This differential technique is applied for label-free super-resolution
absorption microspectroscopy
Quantitative surface free energy with micro-colloid probe pairs
No full textMeasurement of the surface free energy (SFE) of a material allows the prediction of its adhesion properties. Materials can have microscale or sub-microscale surface inhomogeneities, engineered or random, which affect the surface macroscopic behaviour. However, quantitative characterization of the SFE at such length scales remains challenging in view of the variety of instruments and techniques available, the poor knowledge of critical variables and parameters during measurements and the need for appropriate contact models to derive the SFE from the measurements. Failure to characterize adhesion correctly may result in defective components or lengthy process optimization costing billions to industry. Conversely, for planar and homogeneous surfaces, contact angle (CA) measurements are standardized and allow for calculating the SFE using for example the Owen-Wendt model, relying only on the properties of the probing liquids. As such, we assessed and report here a method to correlate quantitative measurements of force-distance curves made with an atomic force microscope (AFM) and with silica and polystyrene (PS) colloidal probe pairs, with quantitative CA measurements and CA-derived SFE values. We measured five surfaces (mica, highly oriented pyrolytic graphite, thermally grown silica on silicon, silicon, and silicon with a super-hydrophobic coating), ranging from hydrophilic to super-hydrophobic, and found an excellent classification of the AFM measurements when these are represented by a set of principal components (PCs), and when both silica and PS colloidal probes are considered together. A regression of the PCs onto the CA measurements allows recovery of the SFE at the length scale of the colloidal probes, which is here ca. 1 micron. We found that once the PC-regression model is built, test sets of only ten AFM force-distance curves are sufficient to predict the local SFE with the calibrated silica and PS colloidal probes
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