Materials both Tough and Soft Ping Gong, Jian
Science (American Association for the Advancement of Science),
04/2014, Letnik:
344, Številka:
6180
Journal Article
Recenzirano
Tough elastomers are created by adapting an approach previously used for hydrogels.
Also see Report by
Ducrot
et al.
Hydrogels and elastomers are soft materials that have similar network structures ...but very different affinities to water. Consisting mostly of water, hydrogels resemble biological soft tissues and have great potential for use in biomedical applications; they tend to be very brittle, like fragile jellies. Elastomers are formed of nonhydrated polymer networks and are widely used as load-dispersing and shock-absorbing materials. They are stretchable but break easily along a notch. On page 186 of this issue, Ducrot
et al.
(
1
) show that the toughness of elastomers can be improved substantially by combining two different network materials, an approach previously applied to hydrogels.
Underwater adhesives are in high demand in both commercial and industrial sectors. Compared with adhesives used in dry (air) environments, adhesives used for wet or submerged surfaces in aqueous ...environments have specific challenges in development and performance. In this review, focus is on adhesives demonstrating macroscopic adhesion to wet/underwater substrates. The current strategies are first introduced for different types of underwater adhesives, and then an overview is provided of the development and performance of underwater adhesives based on different mechanisms and strategies. Finally, the possible research directions and prospects of underwater adhesives are discussed.
Underwater adhesives are in high demand from medical to ocean technology. Key specific challenges are discussed to achieve underwater adhesion, and then an overview of strategies of the existing research and the performances of underwater adhesives achieved is presented. Finally, the possible solutions for the challenges, along with future research directions are discussed.
Metal–organic frameworks (MOFs) are a class of promising materials for diverse heterogeneous catalysis, but they are usually not directly employed for oxygen evolution electrocatalysis. Most reports ...focus on using MOFs as templates to in situ create efficient electrocatalysts through annealing. Herein, we prepared a series of Fe/Ni‐based trimetallic MOFs (Fe/Ni/Co(Mn)‐MIL‐53 accordingly to the Material of Institute Lavoisier) by solvothermal synthesis, which can be directly adopted as highly efficient electrocatalysts. The Fe/Ni/Co(Mn)‐MIL‐53 shows a volcano‐type oxygen evolution reaction (OER) activity as a function of compositions. The optimized Fe/Ni2.4/Co0.4‐MIL‐53 can reach a current density of 20 mA cm−2 at low overpotential of 236 mV with a small Tafel slope of 52.2 mV dec−1. In addition, the OER performance of these MOFs can be further enhanced by directly being grown on nickel foam (NF).
Multimetallic MOFs with modulated compositions have been successfully synthesized and directly adopted as efficient oxygen evolution reaction (OER) catalysts (MOFs=metal–organic frameworks). The Fe/Ni/Co/(Mn)‐MIL‐53 catalyst exhibits a volcano‐type OER activity as a function of compositions. The optimized Fe/Ni/Mn0.4‐MIL‐53/NF catalyst is highly active and ultrastable towards OER catalysis.
•The COVID-19 emerged in Wuhan City and rapidly spread throughout China.•NLR exhibited the largest area under the curve, with the highest specificity and sensitivity.•Elevated NLR can be considered ...independent biomarkers for indicating poor clinical outcomes.
To accumulate evidence that indicated the key role played by virus-triggered inflammation in the 2019-novel coronavirus disease (COVID-19) which emerged in Wuhan City and rapidly spread throughout China.
Age, neutrophil(NEU)-to-lymphocyte (LYM) ratio (NLR), lymphocyte-to-monocyte (MON) ratio, platelet-to-lymphocyte ratio (PLR), and C-reactive protein (CRP) of 93 patients with laboratory confirmed COVID-19 were investigated and compared. The receiver operating characteristic curve was applied to determine the thresholds for five bio-markers, and their prognostic values were assessed via the Kaplan–Meier curve and multivariate COX regression models.
The median age was 46.4 years old, and 37cases were females. A total of 27.8% of patients had been to Wuhan, and 73.1% had contacted with people from Wuhan. Fever (83.8%) and cough (70.9%) were the two most common symptoms. Elevated NLR and age were significantly associated with illness severity. The binary logistic analysis identified elevated NLR (hazard risk HR 2.46, 95% confidence interval CI 1.98–4.57) and age (HR 2.52, 95% CI 1.65–4.83) as independent factors for poor clinical outcome of COVID-19. NLR exhibited the largest area under the curve at 0.841, with the highest specificity (63.6%) and sensitivity (88%).
Elevated age and NLR can be considered independent biomarkers for indicating poor clinical outcomes.
Ultrathin metal–organic framework (MOF) nanosheets (NSs) offer potential for many applications, but the synthetic strategies are largely limited to top‐down, low‐yield exfoliation methods. Herein, ...Ni–M–MOF (M=Fe, Al, Co, Mn, Zn, and Cd) NSs are reported with a thickness of only several atomic layers, prepared by a large‐scale, bottom‐up solvothermal method. The solvent mixture of N,N‐dimethylacetamide and water plays key role in controlling the formation of these two‐dimensional MOF NSs. The MOF NSs can be directly used as efficient electrocatalysts for the oxygen evolution reaction, in which the Ni–Fe–MOF NSs deliver a current density of 10 mA cm−2 at a low overpotential of 221 mV with a small Tafel slope of 56.0 mV dec−1, and exhibit excellent stability for at least 20 h without obvious activity decay. Density functional theory calculations on the energy barriers for OER occurring at different metal sites confirm that Fe is the active site for OER at Ni–Fe–MOF NSs.
Ultrathin, binary MOF nanosheets (NSs) have been successfully prepared for the first time and directly used as efficient oxygen evolution reaction (OER) catalysts. The binary MOF NSs exhibit a highly composition‐dependent OER activity. The optimized Ni–Fe–MOF NSs are highly active and stable towards the OER.
•α″-Fe16N2 was viewed as a mystery material because of inconclusive arguments in 1990s, including many controversial reports at two specific symposia at MMM conferences.•Then the topic was largely ...dropped by the magnetic research community.•The key controversies around this material have been successfully addressed through our long and persistent effort from 2002 to 2012, which was reported at APS Marching Meeting 2010 and INTERMAG 2012.•Since then, α″-Fe16N2 has been picked up as one of the most promising rare-earth-free magnet candidates because of its usage of environment-friendly raw materials, its confirmed giant saturation magnetization and reasonably high magnetic anisotropy constant.•Iron nitride magnet is of great interest as a magnetic material for the applications at relatively low temperature (<150 °C) ranging from speaker magnets, magnets in hard disk drives and all kinds of electrical motors, wind turbines, and other power generation machines.•A perspective review on the synthesis of bulk α″-Fe16N2 compound permanent magnet in past was presented here on the aspects of material processing and magnetic characterizations.•Specifically, we introduce and discuss our efforts to prepare the bulk Fe16N2 compound permanent magnet by using four different approaches, including an ion implantation method, a nanoparticle based approach, a high-temperature nitridation method based on foils, wires and melt-spun ribbons and a low-temperature nitridation method based on foils and ribbons.•With our recent progress and many good on-going activities by researchers worldwide, we believe that α″-Fe16N2 compound permanent magnet is in an accelerating stage to be an alternative environment-friendly magnet candidate.
α″-Fe16N2 had been viewed as a mystery material because of inconclusive arguments in the 1990s, including many controversial reports at two MMM conference symposia, and the topic was then largely dropped by the magnetic research community. The key controversies around this material have now been successfully addressed through our long and persistent efforts from 2002 to 2012, first reported in APS 2010 and then at INTERMAG 2012. Since then, α″-Fe16N2 has been picked up as one of the most promising rare-earth-free magnet candidates because of its use of environment-friendly raw materials, confirmed giant saturation magnetic flux density (2.9 T), and reasonably high magnetic anisotropy constant (1.8 MJ/m3). Its coercivity temperature coefficient (~0.4 Oe/°C) in the range of 27–152 °C is two orders of magnitude lower than that of commercial NdFeB magnets (e.g. N40 ~ −81.9 Oe/K). The iron nitride magnet is of great interest as a magnetic material for applications working at relatively low temperature (<150 °C) and not requesting high coercivity. These applications range from speaker magnets to magnets in hard disk drives, electrical motors, wind turbines, smart phones, audio devices, and other power generation machines. A perspective review on the synthesis of the bulk α″-Fe16N2 compound permanent magnet is presented here on the aspects of material processing and magnetic characterizations. Specifically, we introduce and discuss our efforts to prepare the bulk Fe16N2 compound permanent magnet by using four different approaches, including an ion implantation method, a nanoparticle based approach, a high-temperature nitridation method based on foils, wires, and melt-spun ribbons, and a low-temperature nitridation method based on foils and ribbons. With our recent progress and many on-going activities by researchers worldwide, we believe that the α″-Fe16N2 compound permanent magnet is in an accelerating stage to be an alternative environment-friendly magnet candidate.
Recently BESIII collaboration discovered a charged strange hidden-charm state
Z
cs
(3985) in the
D
s
-
D
∗
0
+
D
s
∗
-
D
0
spectrum. A higher
Z
cs
′
state coupling to
D
¯
s
∗
-
D
∗
0
is expected by ...SU(3)-flavor symmetry, and their bottom partners are anticipated by heavy quark flavor symmetry. Here we study the photoproduction of these exotic states and investigate carefully the background from Pomeron exchange. Our results indicate that the maximal photoproduction cross section of strange partner is around 1–2 orders of magnitude smaller than that of the corresponding non-strange states. The possibility of searching for them in future electron-ion colliders (EIC) is briefly discussed.
Nanomaterials, in addition to their small size, possess unique physicochemical properties that differ from bulk materials, making them ideal for a host of novel applications. Magnetic nanoparticles ...(MNPs) are one important class of nanomaterials that have been widely studied for their potential applications in nanomedicine. Due to the fact that MNPs can be detected and manipulated by remote magnetic fields, it opens a wide opportunity for them to be used in vivo. Nowadays, MNPs have been used for diverse applications including magnetic biosensing (diagnostics), magnetic imaging, magnetic separation, drug and gene delivery, and hyperthermia therapy, etc. Specifically, we reviewed some emerging techniques in magnetic diagnostics such as magnetoresistive (MR) and micro-Hall (μHall) biosensors, as well as the magnetic particle spectroscopy, magnetic relaxation switching and surface enhanced Raman spectroscopy (SERS)-based bioassays. Recent advances in applying MNPs as contrast agents in magnetic resonance imaging and as tracer materials in magnetic particle imaging are reviewed. In addition, the development of high magnetic moment MNPs with proper surface functionalization has progressed exponentially over the past decade. To this end, different MNP synthesis approaches and surface coating strategies are reviewed and the biocompatibility and toxicity of surface functionalized MNP nanocomposites are also discussed. Herein, we are aiming to provide a comprehensive assessment of the state-of-the-art biological and biomedical applications of MNPs. This review is not only to provide in-depth insights into the different synthesis, biofunctionalization, biosensing, imaging, and therapy methods but also to give an overview of limitations and possibilities of each technology.
To present the 12-month prevalence of DSM-IV major depressive disorder (MDD) and severe MDD; to examine sociodemographic correlates and comorbidity; and to describe impairment and service use.
Data ...are from the National Comorbidity Survey-Adolescent Supplement (NCS-A), a nationally representative survey of 10,123 adolescents aged 13 to 18 years that assesses DSM-IV disorders using the Composite International Diagnostic Interview (CIDI) Version 3.0. One parent or surrogate of each participating adolescent was also asked to complete a self-administered questionnaire.
Lifetime and 12-month prevalence of MDD were 11.0% and 7.5%, respectively. The corresponding rates of severe MDD were 3.0% and 2.3%. The prevalence of MDD increased significantly across adolescence, with markedly greater increases among females than among males. Most cases of MDD were associated with psychiatric comorbidity and severe role impairment, and a substantial minority reported suicidality. The prevalence of severe MDD was about one-fourth of that of all MDD cases; estimates of impairment and clinical correlates were of 2- to 5-fold greater magnitude for severe versus mild/moderate depression, with markedly higher rates for suicidal thoughts and behaviors. Treatment in any form was received by the majority of adolescents with 12-month DSM-IV MDD (60.4%), but only a minority received treatment that was disorder-specific or from the mental health sector.
Findings underscore the important public health significance of depression among US adolescents and the urgent need to improve screening and treatment access in this population.
A series of highly luminescent‐active metal–organic frameworks (MOFs) 1–3 with hierarchical pores have been rationally constructed and fully characterized. The predesigned semi‐rigid hexacarboxylate ...ligand hexa4‐(carboxyphenyl)oxamethyl‐3‐oxapentane acid (H6L) has been adapted with various space‐directed N donors (i.e., 2,2’‐bipyridine, 4,4′‐di(1H‐imidazol‐1‐yl)‐1,1′‐biphenyl, and 1,3,5‐tri(1H‐imidazol‐1‐yl)benzene) from a bidentate V‐shape to a tridentate Y‐shape. This family of multifunctional MOF materials represents a variety of potential applications in the following aspects: first, as luminescent sensors that show a fast and sensitive detection for pollutant CrO42− and Cr2O72− ions in aqueous media; second, as adsorbents that can rapidly remove harmful organic dyes; third, as an antenna that can effectively sensitize visible‐light‐emitting Tb3+ ions. These multifunctional MOF materials combine optical‐sensing, adsorption, and sensitization properties, thus are very useful in many potential applications. Furthermore, these materials have proved to be reusable.
All in one: A series of multifunctional cadmium metal–organic frameworks (MOFs) has been rationally constructed that combines sensor properties for the excellent detection of pollutant CrO42− and Cr2O72− ions, sensitizer properties for the effective and selective sensitization of the visible‐emitting Tb3+ ion in aqueous media, and absorbent abilities for the fast removal of the methylene blue (MB) dye. Furthermore, these MOF materials are recyclable (see figure).
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