Display omitted
•Grain boundary diffusion process for cost-effective Nd-Fe-B magnets is reviewed.•Diffusion sources are developing for less consumption of critical rare ...earths.•Properties-microstructure relationship is governed by diffusion source and process.•Different strategies for various types of magnets are provided and compared.
Rare earth permanent magnets are essential in a plethora of electrical machine and renewable energy. Nd-Fe-B magnets account for half of the market share of permanent magnets due to their excellent room temperature magnetic properties. However, the next generation applications require high coercivity at elevated temperatures. For this purpose, heavy rare earths (HRE) have been used to enhance the anisotropy field of the magnets but it not only increases the cost but also reduces the remanence. Grain boundary diffusion process (GBDP), as an emerging technology appeared in this century, offers the best route to improve the coercivity of Nd-Fe-B magnets with low HRE consumption, and has been well studied and rapidly industrialized. In this review, based on the world-wide progress and the results from the authors’ groups, a comprehensive critical description is given on the fundamentals and development of GBDP. The GBDPs based on various diffusion sources and processes, and those for different types of magnets are compared and summarized. The coercivity enhancement mechanisms are discussed in detail to understand the structure-properties relationships. The cost reduction and high-efficient use of critical elements are analyzed. The challenges and opportunities are also highlighted for future development of GBDP and cost-effective permanent magnets.
Noble metal nanoparticles have been extensively studied to understand and apply their plasmonic responses, upon coupling with electromagnetic radiation, to research areas such as sensing, ...photocatalysis, electronics, and biomedicine. The plasmonic properties of metal nanoparticles can change significantly with changes in particle size, shape, composition, and arrangement. Thus, stabilization of the fabricated nanoparticles is crucial for preservation of the desired plasmonic behavior. Because plasmonic nanoparticles find application in diverse fields, a variety of different stabilization strategies have been developed. Often, stabilizers also function to enhance or improve the plasmonic properties of the nanoparticles. This review provides a representative overview of how gold and silver nanoparticles, the most frequently used materials in current plasmonic applications, are stabilized in different application platforms and how the stabilizing agents improve their plasmonic properties at the same time. Specifically, this review focuses on the roles and effects of stabilizing agents such as surfactants, silica, biomolecules, polymers, and metal shells in colloidal nanoparticle suspensions. Stability strategies for other types of plasmonic nanomaterials, lithographic plasmonic nanoparticle arrays, are discussed as well.
For practical engineering structures, fatigue is one of the main factors affecting their safety and durability. Under long-term service conditions, the minor damage will be affected by fatigue ...loading and expand to macroscopic cracks, affecting the structure’s service performance. Based on the sensitivity of Lamb waves to minor and initial damage, a damage monitoring method for fatigue crack propagation is proposed. By carrying out fatigue crack propagation tests under constant amplitude loading, the Paris equation of 316L steel and damage signals at different crack growth stages were obtained. Combined with damage monitoring tests and finite element analysis, the relationship between the phase damage index (PDI), amplitude damage index (ADI), signal correlation coefficient, and fatigue crack propagation length was studied. Compared with PDI and ADI, the signal correlation coefficient is more sensitive to crack initiation, which can be selected as the damage monitoring index in the initial stage of crack growth. With the increase of fatigue crack propagation length, the peak time of the direct wave signal gradually moves backward, which shows an obvious phase change. In the whole fatigue crack growth stage, PDI and crack length show a monotonically changing trend. By using the stress intensity factor as the conversion parameter, a prediction model of the fatigue crack propagation rate based on PDI was established. Compared to the fatigue crack propagation rate measured by experiments, the relative error of the predicted results is 10%, which verifies the accuracy of the proposed damage monitoring method.
The adhesion ability of Lactobacillus plantarum affects retention time in the human gastro-intestinal tract, as well as influencing the interaction with their host. In this study, the relationship ...between the adhesion activity of, and metabolic changes in, L. plantarum ATCC 14917 under initial acid and alkali stress was evaluated by analyzing auto-aggregation, protein adhesion and cell adhesion in vitro. Based on scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis, the morphology of the bacteria became thickset and the thickness of their cell walls decreased under initial alkali stress. The fold changes of auto-aggregation, adhere to mucin and HT-29 cell lines of L. plantarum ATCC 14917 in the acid group were increased by 1.141, 1.125 and 1.156, respectively. But decreased significantly in the alkali group (fold changes with 0.842, 0.728 and 0.667). Adhesion-related protein increased in the acid group but declined in the alkali group at the mRNA expression level according to real time polymerase chain reaction (RT-PCR) analysis. The changes in the metabolite profiles of L. plantarum ATCC 14917 were characterized using Ultra-Performance Liquid Chromatography-Electrospray ionization-Quadrupole-Time of Flight-mass spectrometry (UPLS-ESI-Q-TOF-MS). In the alkali group, the content of a lot of substances involved in the energy and amino acid metabolism decreased, but the content of some substances involved in the energy metabolism was slightly increased in the acid group. These findings demonstrate that energy metabolism is positively correlated with the adhesion ability of L. plantarum ATCC 14917. The amino-acids metabolism, especially the amino acids related to pH-homeostasis mechanisms (lysine, aspartic acid, arginine, proline and glutamic acid), showed an obvious effect on the adhesion ability of L. plantarum ATCC 14917. This investigation provides a better understanding of L. plantarum's adhesion mechanisms under initial pH stress.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Research at the interface of synthetic materials, biochemistry, and analytical techniques has enabled sensing platforms for applications across many research communities. Herein we review the ...materials used as affinity agents to create surface-enhanced Raman spectroscopy (SERS) sensors. Our scope includes those affinity agents (antibody, aptamer, small molecule, and polymer) that facilitate the intrinsic detection of targets relevant to biology, medicine, national security, environmental protection, and food safety. We begin with an overview of the analytical technique (SERS) and considerations for its application as a sensor. We subsequently describe four classes of affinity agents, giving a brief overview on affinity, production, attachment chemistry, and first uses with SERS. Additionally, we review the SERS features of the affinity agents, and the analytes detected by intrinsic SERS with that affinity agent class. We conclude with remarks on affinity agent selection for intrinsic SERS sensing platforms.
As an economically important flatfish in Asia, Japanese flounder is threatened by continuously rising temperatures due to global warming. To understand the molecular responses of this species to ...temperature stress, adult Japanese flounder individuals were treated with two kinds of heat stress-a gradual temperature rise (GTR) and an abrupt temperature rise (ATR)-in aquaria under experimental conditions. Changes in histopathology, programmed cell death levels and the oxidative stress status of gills were investigated. Histopathology showed that the damage caused by ATR stress was more serious. TUNEL signals confirmed this result, showing more programmed cell death in the ATR group. In addition, reactive oxygen species (ROS) levels and the 8-O-hDG contents of both the GTR and ATR groups increased significantly, and the total superoxide dismutase (T-SOD) activities and total antioxidant capacity (T-AOC) levels decreased in the two stressed groups, which showed damage to antioxidant systems. Meanwhile, RNA-seq was utilized to illustrate the molecular mechanisms underyling gill damage. Compared to the control group of 18 °C, 507 differentially expressed genes (DEGs) were screened in the GTR group; 341 were up-regulated and 166 were down-regulated, and pathway enrichment analysis indicated that they were involved in regulation and adaptation, including chaperone and folding catalyst pathways, the mitogen-activated protein kinase signaling (MAPK) pathway and DNA replication protein pathways. After ATR stress, 1070 DEGs were identified, 627 were up-regulated and 423 were down-regulated, and most DEGs were involved in chaperone and folding catalyst and DNA-related pathways, such as DNA replication proteins and nucleotide excision repair. The annotation of DEGs showed the great importance of heat shock proteins (HSPs) in protecting Japanese flounder from heat stress injury; 12
genes were found after GTR, while 5
genes were found after ATR. In summary, our study records gill dysfunction after heat stress, with different response patterns observed in the two experimental designs; chaperones were activated to defend heat stress after GTR, while replication was almost abandoned due to the severe damage consequent on ATR stress.
The continuous increase in the output of Nd-Fe-B permanent magnets leads to the increasing consumption of rare earth (RE) metals of Nd, Pr, Tb and Dy. As a result, a serious unbalanced utilization of ...RE resource occurs. To reduce the use of these critical REs, high abundance REs of Y, La, Ce and even Gd and Ho have been proposed to partly substitute Pr and Nd in sintered magnets and rapid-quenched nanocrystalline magnetic powders. Recently, the cost-effective RE-Fe-B magnets without Nd, Pr, Tb and Dy have also been developed. This type of magnet is preliminarily designed to bridge the magnetic properties gap between hard ferrites and bonded Nd-Fe-B magnets, which shows the potential applications in voice coil motor, spindle motors and magnetic resonance imaging systems. This review summarizes the progress of RE-Fe-B-type magnets containing no Nd, Pr, Dy and Tb based on the world-wide investigations and our recent findings. The fundamentals of intrinsic magnetic properties of Y, La, Ce based RE2Fe14B phases are introduced first. The relationship between magnetic properties and microstructure of rapidly quenched and bulk RE-Fe-B magnets with nanocrystalline structure is then emphatically discussed. Hard magnetic properties and performance/cost ratio of various RE-Fe-B alloy systems are summarized and compared. Furthermore, the current discoveries and the existing challenges are discussed. Some potential strategies for the future research in this field are finally proposed.
Liver metastasis is a major cause of colorectal cancer‐related death. Although DNase I displays antimetastatic activity by inhibition of NETs, its clinical use is limited due to its short biologic ...half‐life. AAV‐mediated gene expression of DNase I is a novel therapeutic strategy that could reduce the development of liver metastases through modulation of innate and adaptive tumor immunity.
Liver metastasis is the main cause of colorectal cancer (CRC)‐related death. Neutrophil extracellular traps (NETs) play important roles in CRC progression. Deoxyribonuclease I (DNase I) has been shown to alter NET function by cleaving DNA strands comprising the NET backbone. Moreover, DNase I displays high antimetastatic activity in multiple tumor models. To circumvent long‐term daily administrations of recombinant DNase I, we have developed an adeno‐associated virus (AAV) gene therapy vector to specifically express DNase I in the liver. In this study, we demonstrate AAV‐mediated DNase I liver gene transfer following a single intravenous injection suppresses the development of liver metastases in a mouse model of CRC liver metastasis. Increased levels of neutrophils and NET formation in tumors are associated with poor prognosis in many patients with advanced cancers. Neutrophil infiltration and NET formation were inhibited in tumor tissues with AAV‐DNase I treatment. This approach restored local immune responses at the tumor site by increasing the percentage of CD8+ T cells while keeping CD4+ T cells similar between AAV‐DNase I and AAV‐null treatments. Our data suggest that AAV‐mediated DNase I liver gene transfer is a safe and effective modality to inhibit metastasis and represents a novel therapeutic strategy for CRC.
Colonization with methicillin-resistant
Staphylococcus aureus
is associated with increased infection risk after hospital discharge. In a multicenter, randomized trial, a program of MRSA ...decolonization at home led to a significantly lower risk of MRSA infection over a 1-year period than hygiene education alone.
Lead is a widespread environmental pollutant with serious adverse effects on human health, but the mechanism underlying its toxicity remains elusive. This study aimed to investigate the role of ...miR-584–5p / Ykt6 axis in the toxic effect of lead on HK-2 cells and the related mechanism. Our data suggested that lead exposure caused significant cytotoxicity, DNA and chromosome damage to HK-2 cells. Mechanistically, lead exposure down-regulated miR-584–5p and up-regulated Ykt6 expression, consequently, autophagosomal number and autophagic flux increased, lysosomal number and activity decreased, exosomal secretion increased. Interestingly, when miR-584–5p level was enhanced with mimic, autophagosomal number and autophagic flux decreased, lysosomal number and activity increased, ultimately, exosomal secretion was down-regulated, which resulted in significant aggravated toxic effects of lead. Further, directly blocking exosomal secretion with inhibitor GW4869 also resulted in exacerbated toxic effects of lead. Herein, we conclude that miR-584–5p / Ykt6 - mediated autophagy - lysosome - exosome pathway may be a critical route affecting the toxic effects of lead on HK-2 cells. We provide a novel insight into the mechanism underlying the toxicity of lead on human cells.
•Lead produced significant toxic effects on HK-2 cells.•Lead activated miR-584–5p / Ykt6 axis in HK-2 cells.•miR-584–5p / Ykt6 regulated autophagy - lysosome - exosome pathway.•Autophagy - lysosome - exosome played a critical role in the toxicity of lead.
PDF
