A wide application of carbon nanotubes (CNTs) is on the way owing to their unique structural, optical, mechanical and electronic properties, high specific surface area, and facile functionalization. ...As a result, human beings will inevitably be exposed to CNTs, especially when the tubes are utilized as diagnostic and therapeutic tools to better understand, detect, and treat human diseases. Therefore the new subject of nanotoxicology, which is the study of the toxicity of nanomaterials, is now gaining public concern. This review provides an overview and comments on recent advances (mostly within the last 3years) in the toxicology of CNTs, including their toxicity targeted to cells, organs, tissues and the whole organism, including mammals and other species (e.g. aquatic species, plants, and bacteria). Not only these traditional subjects of toxicological study but the interaction of CNTs and biomacromolecules is also covered so that the mechanism of their toxicity may be understood and their undesirable properties are more likely to be avoided.
Display omitted
•CNT diameter and surface area govern the stability of adsorbed proteins.•More BSA was loaded and destabilized on smaller CNTs.•Protein corona reduces the cytotoxicity of CNTs
In this ...work, we investigated and compared carbon nanotubes (CNTs) of different diameters regarding their interaction with bovine serum albumin (BSA) and their ability to alter protein structure. BSA was exposed to CNT solutions, and the effects were assessed by utilizing fluorescence spectroscopy, UV–vis absorption spectroscopy, circular dichroism (CD) spectroscopy, transmission electron microscopy (TEM), bichinchoninic acid (BCA) and zeta-potential measurement assays. We demonstrate that CNT diameter and surface area play key roles in influencing the stability of adsorbed proteins. Results showed that the secondary and tertiary structural stability of BSA decreased upon adsorption onto CNTs, with greater decrease on smaller-diametered nanotubes. Besides, more protein was loaded onto CNTs with small diameter, reducing the cytotoxicity. This study, therefore, provides fundamental information for the influence of CNT diameter and surface on protein behavior, which may be helpful to understand toxic effects of CNTs and prove beneficial for developing novel biomedical devices and safe use of nanomaterials.
Driving solutions for power semiconductor devices are experiencing new challenges since the emerging wide bandgap power devices, such as silicon carbide (SiC), with superior performance become ...commercially available. Generally, high switching speed is desired due to the lower switching loss, yet high <inline-formula> <tex-math notation="LaTeX">dv/dt </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">di/dt </tex-math></inline-formula> can result in elevated electromagnetic interference (EMI) emission, false-triggering, and other detrimental effects during switching transients. Active gate drivers (AGDs) have been proposed to balance the switching losses and the switching speed of each switching transient. The review of the in-existence AGD methodologies for SiC devices has not been reported yet. This review starts with the essence of the slew rate control and its significance. Then, a comprehensive review categorizing the state-of-the-art AGD methodologies is presented. It is followed by a summary of the AGDs control and timing strategies. In this work, using AGD to reduce the EMI noise of a 10-kV SiC MOSFET system is reported. This work also highlights other capabilities of AGDs, including reliability enhancement of power devices and rebalancing the mismatched electrical parameters of parallel- and series-connected devices. These application scenarios of AGDs are validated via simulation and experimental results.
Listeria monocytogenes (L. monocytogenes), an important food-borne pathogenic microorganism, has resistance immune function to many commonly used drugs. Myristic acid is a traditional Chinese herbal ...medicine, but it has been rarely used as a food additive, limiting the development of natural food preservatives. In this study, the antibacterial activity and mechanism of myristic acid against L. monocytogenes were studied. The minimum inhibitory concentration (MIC) of myristic acid against 13 L. monocytogenes strains ranged from 64 to 256 μg ml
. The time-kill assay demonstrated that when myristic acid was added to dairy products, flow cytometry confirmed that myristic acid influenced cell death and inhibited the growth of L. monocytogenes. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and NPN uptake studies illustrated that myristic acid changed the bacterial morphology and membrane structure of L. monocytogenes, which led to rapid cell death. Myristic acid could bind to DNA and lead to changes in DNA conformation and structure, as identified by fluorescence spectroscopy. Our studies provide additional evidence to support myristic acid being used as a natural antibacterial agent and also further fundamental understanding of the modes of antibacterial action.
By using spectroscopic methods, we probed the interaction of Ag
+ with bovine serum albumin (BSA) in an aqueous environment. Fluorescence of BSA quenched by Ag
+ is a dynamic quenching process. Two ...binding modes–a strong one at low concentration of Ag
+ and a weak one at high concentration were found. The association constant (
K
A) and the number of binding sites (
n) were 4.88
×
10
3
M
−
1
and 1.17 for strong binding, and 17.6
M
−
1
and 0.547 for weak binding at 293
K. The results of thermodynamic parameters Δ
H
θ
, Δ
G
θ
and Δ
S
θ
for instinct binding modes at different temperatures indicated that the hydrogen bonding and van der Waals interaction play a major role for low Ag
+/BSA ratio while electrostatic association for high Ag
+/BSA ratio. Data of UV–Vis and Circular dichroism (CD) suggested that with the increasing amount of Ag
+, the secondary structure undergoes a decrease in α-helix and an increase in β content and the backbone of BSA experiences a micro-environmental alteration. Furthermore, the distance
r between donor (Trp-212) and acceptor (Ag
+) was evaluated to be 10
nm according to nonradiative energy transfer theory.
► A spectroscopy-based assessment model was performed to estimate the binding of Ag
+ to bovine serum albumin (BSA). ► Ag
+ was found not only to change the microenvironment of fluorescent amino acid residues of BSA but also to cause alterations in the secondary and tertiary structural content of protein. ► Two binding modes occur according to Ag
+ concentration, which is different other metal bindings.
Pneumonia is a life-threatening disease. Computer tomography (CT) imaging is broadly used for diagnosing pneumonia. To assist radiologists in accurately and efficiently detecting pneumonia from CT ...scans, many deep learning methods have been developed. These methods require large amounts of annotated CT scans, which are difficult to obtain due to privacy concerns and high annotation costs. To address this problem, we develop a three-level optimization based method which leverages CT data from a source domain to mitigate the lack of labeled CT scans in a target domain. Our method automatically identifies and downweights low-quality source CT data examples which are noisy or have large domain discrepancy with target data, by minimizing the validation loss of a target model trained on reweighted source data. On a target dataset with 2218 CT scans and a source dataset with 349 CT images, our method achieves an F1 score of 91.8% in detecting pneumonia and an F1 score of 92.4% in detecting other types of pneumonia, which are significantly better than those achieved by state-of-the-art baseline methods.
•Strain-specific biofilm-forming ability was found in B. cereus group.•Nutrient-rich condition enhanced the biofilm formation of B. cereus group.•Dry formulation of B. thuringiensis enhanced their ...adhesion on spinach leaves.•Strength of adhesion was not improved by the formulation of B. thuringiensis.
Bacillus thuringiensis-based commercial products as a biopesticide have been used for more than 60 years in agriculture. However, as one of the species in B. cereus group, B. thuringiensis has been considered as an emerging hazard with the potential to cause food toxico-infections. The present study aimed to evaluate the biofilm-forming ability of B. thuringiensis biopesticide strains and their attachment on spinach, compared to foodborne B. cereus strains. Biofilm formations of tested strains were found to be strain-specific and affected by the nutrient conditions more than the incubation time. Nutrient starvation conditions generally reduced the biofilm formation of tested B. thuringiensis and B. cereus strains, particularly B. thuringiensis ABTS-1857 strain was found as the nonbiofilm former in starvation conditions. It is worth mentioning that B. thuringiensis SA-11 strain showed stronger biofilm-forming ability with more air–liquid interface biofilm than the other two B. thuringiensis biopesticide strains, but no such higher attachment of B. thuringiensis SA-11 to spinach was observed. These results indicate that B. thuringiensis SA-11 strain can enter the food processing lines by the attachment on spinach leaves, and it has the potential to form biofilms throughout the processing lines or the production environment when sufficient nutrients are available. However, more biofilm tests of B. thuringiensis biopesticide strains in the vegetable production chain should be performed. The dry formulation of commercial B. thuringiensis biopesticides enhanced their adhesion on spinach leaves, whereas the strength of adhesion was not improved by the formulation. In addition, 1–2 log reductions of spores after the intensive washing of spinach leaves in the lab were detected. However, the log reduction due to the actual washing done by the food processing companies in large-volume washing baths or by consumers at home would be limited and less than this lab simulation.
Graphene has evoked extensive interests for its abundant physical properties and potential applications. It is reported that the interfacial electronic interaction between metal and graphene would ...give rise to charge transfer and change the electronic properties of graphene, leading to some novel electrical and magnetic properties in metal-graphene heterostructure. In addition, large specific surface area, low density and high chemical stability make graphene act as an ideal coating material. Taking full advantage of the aforementioned features of graphene, we synthesized graphene-coated Fe nanocomposites for the first time and investigated their microwave absorption properties. Due to the charge transfer at Fe-graphene interface in Fe/G, the nanocomposites show distinct dielectric properties, which result in excellent microwave absorption performance in a wide frequency range. This work provides a novel approach for exploring high-performance microwave absorption material as well as expands the application field of graphene-based materials.
Display omitted
•Urines from female and male residents under cadmium exposure were investigated by mass spectrometry-based metabolomics.•Biomarkers and metabolic pathways related to cadmium-induced ...nephrotoxicity were characterized.•This study might provide information to reflect the body burden and help improve health policy for risk assessment.
Cadmium is a well-known hazardous pollutant that mainly comes from dietary, tobacco and occupational exposure, posing threat to kidney. However, there is still a lack of systematic study on metabolic pathways and urinary biomarkers related to its nephrotoxicity under cadmium exposure for both females and males. In this study, a mass spectrometry-based metabolomics investigation of a cohort of 144 volunteers was conducted to explore sex-specific metabolic alteration and to screen biomarkers related to cadmium-induced nephrotoxicity. When the concentration of urinary cadmium increased, creatine pathway, amino acid metabolism especially the tryptophan metabolism, aminoacyl-tRNA biosynthesis, and purine metabolism were primarily influenced regardless of the gender. Also, the most specific biomarkers linked with nephrotoxicity based on the statistical analysis were detected including creatine, creatinine, l-tryptophan, adenine and uric acid. The study outcome might provide information to reflect the body burden and help improve health policy for risk assessment.
Anthocyanins from the purple Solanum tuberosum newly cultivated by the Taian Academy of Agricultural Sciences were extracted and analyzed using high-performance liquid chromatography (HPLC) and ...UV–vis spectroscopy. Four individual anthocyanins were detected as the major components, and the total anthocyanin content was 273.5 ± 14.3 mg of cyanidin-3-glucoside equiv/100 g of dry seeds. Results of color stability showed that the purple S. tuberosum anthocyanins (PSTAs) are more stable under low pH and temperatures. Heat and general food additives have fine compatibility with PSTAs; however, they are very sensitive with oxidant and reduction. The influence of PSTAs on Cr(VI) targeted to bovine serum albumin (BSA) was also studied. The quenching of BSA fluorescence caused by Cr(VI) could be delayed by PSTAs. UV–vis and circular dichroism (CD) data suggested that PSTAs can protect the secondary and tertiary structures of BSA by probably interacting with Cr(VI) in advance.
PDF
