Abstract
Metalenses—flat lenses made with optical metasurfaces—promise to enable thinner, cheaper, and better imaging systems. Achieving a sufficient angular field of view (FOV) is crucial toward ...that goal and requires a tailored incident-angle-dependent response. Here, we show that there is an intrinsic trade-off between achieving a desired broad-angle response and reducing the thickness of the device. Like the memory effect in disordered media, this thickness bound originates from the Fourier transform duality between space and angle. One can write down the transmission matrix describing the desired angle-dependent response, convert it to the spatial basis where its degree of nonlocality can be quantified through a lateral spreading, and determine the minimal device thickness based on such a required lateral spreading. This approach is general. When applied to wide-FOV lenses, it predicts the minimal thickness as a function of the FOV, lens diameter, and numerical aperture. The bound is tight, as some inverse-designed multi-layer metasurfaces can approach the minimal thickness we found. This work offers guidance for the design of nonlocal metasurfaces, proposes a new framework for establishing bounds, and reveals the relation between angular diversity and spatial footprint in multi-channel systems.
Ulcerative colitis (UC), which is a major form of inflammatory bowel disease (IBD), is a chronic relapsing disorder of the gastrointestinal tract affecting millions of people worldwide. Alternative ...natural therapies, including dietary changes, are being investigated to manage or treat UC since current treatment options have serious negative side effects. There is growing evidence from animal studies and human clinical trials that diets rich in anthocyanins, which are pigments in fruits and vegetables, protect against inflammation and increased gut permeability as well as improve colon health through their ability to alter bacterial metabolism and the microbial milieu within the intestines. In this review, the structure and bioactivity of anthocyanins, the role of inflammation and gut bacterial dysbiosis in UC pathogenesis, and their regulation by the dietary anthocyanins are discussed, which suggests the feasibility of dietary strategies for UC mitigation.
As one of the main hydration products, Ca(OH)2 has important effects on mechanical properties and durability of hardened cementitious materials. In this study, Ca(OH)2 precipitates were synthesized ...by continuous feeding of CaCl2 and NaOH solutions into a bulk solution containing triethanolamine (TEA) or diethanolamine (DEA). Analytical techniques including electric conductivity measurement, TOC, ICP − OES, XRD, FTIR and SEM were employed to investigate the impacts of the alkanolamines on the precipitation process and morphology of the synthetic Ca(OH)2. Results show that TEA strongly hinders the nucleation and growth of Ca(OH)2 precipitate due to the complexation effect with Ca2+ ions in solution. The chemical incorporation of TEA into the lattice structure greatly disrupts lattice structure of the obtained Ca(OH)2 precipitates and alters the morphology from typical hexagonal prism of pure portlandite to vertically stacked or randomly agglomerated Ca(OH)2 lamellae crystals with much smaller size. In contrast, DEA exhibits little effect on the precipitation process and morphology of portlandite.
One of the breakthroughs in biomaterials and regenerative medicine in the latest decade is the finding that matrix stiffness affords a crucial physical cue of stem cell differentiation. This ...statement was recently challenged by another understanding that protein tethering on material surfaces instead of matrix stiffness was the essential cue to regulate stem cells. Herein, we employed nonfouling poly(ethylene glycol) (PEG) hydrogels as the matrix to prevent nonspecific protein adsorption, and meanwhile covalently bound cell-adhesive arginine-glycine-aspartate (RGD) peptides onto the hydrogel surfaces in the form of well-defined nanoarrays to control specific cell adhesion. This approach enables the decoupling of the effects of matrix stiffness and surface chemistry. Mesenchymal stem cells (MSCs) were cultured on four substrates (two compressive moduli of the PEG hydrogels multiplied by two RGD nanospacings) and incubated in the mixed osteogenic and adipogenic medium. The results illustrate unambiguously that matrix stiffness is a potent regulator of stem cell differentiation. Moreover, we reveal that RGD nanospacing affects spreading area and differentiation of rat MSCs, regardless of the hydrogel stiffness. Therefore, both matrix stiffness and nanoscale spatial organization of cell-adhesive ligands direct stem cell fate.
The identification and quantification of pharmaceutical and personal care products (PPCPs) in aquatic ecosystems is critical to further studies and elucidation of their fate as well as the potential ...threats to aquatic ecology and human health. This study used mass balances to analyse the sources, transformation, and transport of PPCPs in rivers based on the population and consumption habits of residents, the removal level of sewage treatment, the persistence and partitioning mechanisms of PPCPs, hydrological conditions, and other natural factors. Our results suggested that in an urbanized river of Guangzhou City, China, the daily consumption of PPCPs was the main reason for the variety of species and concentrations of PPCPs. Through the determination of PPCPs in the river water samples and a central composite design (CCD) methodology, the dominant elimination mechanisms of caffeine and carbamazepine from river water were photolysis and biodegradation, but that of triclosan was sorption rather than biodegradation. The mass data of 3 PPCPs were estimated and corroborated using the measured data to evaluate the accuracy of the mass balance. Finally, caffeine, carbamazepine and triclosan discharged from the Shijing River into the Pearl River accounted for 97.81%, 99.52%, and 28.00%, respectively, of the total mass of these three compounds in the surface water of Shijing River. The results suggest that photolysis are the main process of natural attenuation for selected PPCPs in surface waters of river systems, and the transfer processes of PPCPs is mainly attributed to riverine advection. In addition, the low concentration of dissolved oxygen inhibited the degradation of PPCPs in the surface water of Shijing River.
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•13 of 15 Target PPCPs were detected in the surface water of the Shijing River.•A mass balance of caffeine, carbamazepine and triclosan was addressed.•The source of PPCPs in urban rivers depends on the consumption of residents and the improvement of sewage treatment system.•The fate of these PPCPs was mainly dependent on advection and photolysis.
The occurrence and fate of PPCPs by combining field observations, laboratory experiments and a mass balance analysis was investigated in an urbanized river.
Many estuaries have undergone severe saltwater intrusion in addition to simultaneously experiencing serious heavy metal pollution. To explore the effect of water density stratification associated ...with saltwater intrusion on the behaviour of heavy metals (Cr, Co, Ni, Cu, Zn, As, Pb, and Cd) in water and sediments, a field survey was conducted in a typical estuary (Modaomen). The content, distribution, and mobility of heavy metals were investigated, as well as the influence of environmental factors on their future. The results showed that Modaomen estuary was characterised by a notable variation in salinity along the estuary, presenting total freshwater upstream, high salinity stratification water in the mouth, and saltwater offshore. Dissolved metals presented a prominent gradient vertically, with 1.2–2.1 times higher in bottom water than in surface water and the highest contents in the highly–stratified bottom water. Elevated salinity and restricted mixing induced by water stratification were likely the causes of this outcome. The distribution of heavy metals in sediments was greatly governed by grain size, Fe/Mn (hydr)oxides, total organic carbon, salinity, and dissolved oxygen. Comprehensive evaluation, combined with total contents and chemical fractions of heavy metals, indicated that internal release from sediments contributed a considerable part to the higher levels of heavy metals in bottom water, particularly for Zn and Pb, which was fully consistent with their status in water body, and elevated salinity and lack of oxygen were likely the primary driving factors. During the phase-partition processes between bottom water and sediments, partitioning coefficients were markedly lower in the highly stratified zone, implying that saltwater intrusion facilitated the mobility and repartitioning processes of metals. Because of increased levels and toxicity of heavy metals in water and extended residence time during saltwater intrusion, the potential damage to the estuarine ecosystem should receive more attention.
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•Internal release from sediments is a considerable part for metals in bottom water.•Water stratification restricts vertical mixing of metals in water column.•The exchange and partitioning process of metals is governed by saltwater intrusion.•Fe/Mn oxides, salinity and DO regulate the mobility of metals in sediments.
Liquid biopsy is a revolutionary strategy in cancer diagnosis and prognosis prediction, which is used to analyze cancer cells or cancer‐derived products through biofluids such as blood, urine and so ...on. Exosomes play a crucial role in mediating cell communication. A growing number of studies have reported that exosomes are involved in tumorigenesis, tumor growth, metastasis and drug resistance by delivering cargos including nucleic acids and protein. Thus, exosomes, as a new type of liquid biopsy, have the potential to be diagnostic or prognostic biomarkers. Herein, we elaborate on the current methods and introduce novel techniques for exosome isolation and characterization. Moreover, we elucidate the advantages of exosomes compared to other biological components in liquid biopsy and summarize the different exosomal biomarkers in cancer diagnosis and prognosis prediction.
Wetlands are recognized as one of the most important natural environments for humans. At the same time, heavy metal pollution has an important impact on wetlands. China's Raoyanghe Wetland is one of ...the most important natural wild species gene banks in China. Eight heavy metal elements (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) in surface layer and deep layer soils were analyzed using statistical-, pollution index-, and Nemerow index-based methods, the Hakanson potential ecological risk index method, and principal component and cluster analyses. The results showed that the maximum concentrations of heavy metals exceeded the background values in the core area and buffer zone of the wetland, but the heavy metal content of the soils was generally low and did not exceed 30%. With the exception of Hg, heavy metal concentrations showed strong spatial differentiation. The differences between the surface layer and deep layer soils of the core area were smaller than in the buffer zone. With the exception of Cd, a clear vertical zonation in the buffer zone soils was observed, showing greater evidence of external influences in this zone than the core. With the exception of partial surface soils, which indicated a safe level of pollution in the core area, all other soils were classified as having a 'mild' level of pollution. Thus, the wetland is moderately polluted, with both the core area and the buffer zone presenting a low level of potential ecological risk. According to the results of the present study, heavy metal contaminants in the wetland soils were found to be derived mainly from the natural sources.
Micropatterns of gold (Au) nanoarrays on inorganic and polymeric substrates were fabricated by combining block copolymer micelle nanolithography to obtain gold nanoarrays on glass, photolithography ...plus hydrofluoric acid (HF) etching to generate microislands, and transfer lithography to shift the gold micro/nanopatterns from glass to a bioinert poly(ethylene glycol) (PEG) hydrogel surface. Further the modification of the gold nanodots via cell-adhesive arginine-glycine-aspartate (RGD) ligands was carried out to achieve peptide micro/nanopatterns. Whereas the micro/nanopatterns of noble metals could be useful in various applications, the peptide micro/nanopatterns especially enable persistent cell localization on adhesive micropatterns of RGD nanoarrays on the background of potently nonfouling PEG hydrogels, and thus offer a powerful tool to investigate cell-material interactions on both molecular and cellular levels. As a demonstration, we cultured human mesenchymal stem cells (hMSCs) on micro/nanopatterns with RGD nanoarrays of nanospacings 46 and 95 nm, and with micropans of side lengths 35 and 65 μm (four groups in total). The osteogenic and adipogenic differentiation of hMSCs was conducted, and the potential effect of RGD nanospacing and the effect of cell spreading size on cell differentiation were decoupled for the first time. The results reveal that RGD nanospacing, independent of cell spreading size, acts as a strong regulator of cell tension and stem cell differentiation, which cannot be concluded unambiguously based on either merely micropatterns or nanopatterns.
Stem cells are capable of sensing and responding to the mechanical properties of extracellular matrixes (ECMs). It is well-known that, while osteogenesis is promoted on the stiff matrixes, ...adipogenesis is enhanced on the soft ones. Herein, we report an “abnormal” tendency of matrix-stiffness-directed stem cell differentiation. Well-defined nanoarrays of cell-adhesive arginine-glycine-aspartate (RGD) peptides were modified onto the surfaces of persistently nonfouling poly(ethylene glycol) (PEG) hydrogels to achieve controlled specific cell adhesion and simultaneously eliminate nonspecific protein adsorption. Mesenchymal stem cells were cultivated on the RGD-nanopatterned PEG hydrogels with the same RGD nanospacing but different hydrogel stiffnesses and incubated in the induction medium to examine the effect of matrix stiffness on osteogenic and adipogenic differentiation extents. When stem cells were kept at a low density during the induction period, the differentiation tendency was consistent with the previous reports in the literature; however, both lineage commitments were favored on the stiff matrices at a high cell density. We interpreted such a complicated stiffness effect at a high cell density in two-dimensional culture as the interplay of matrix stiffness and cell–cell contact. As a result, this study strengthens the essence of the stiffness effect and highlights the combinatory effects of ECM cues and cell cues on stem cell differentiation.
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