Poly(2-vinyl pyridine), P2VP, films display a surface pattern of craters in a dried state after being immersed in aqueous solutions containing HAuCl4 and its mixtures with low contents of K2CO3. The ...morphologies of craters indicate that the formation of craters involves three stages through film blistering and drying: (i) the permeability of water and solutes to swell P2VP films, (ii) partial wetting of liquid droplets near the substrate interface in the presence of the P2VP film, and (iii) evaporation-driven flows. The three stages produce the swelling pressure, Laplace pressure, and interplays among capillary flows, Marangoni flows, and pinning effects, respectively, by which craters of different dimensions and morphologies are obtained. The first stage softens the P2VP films and produces swelling pressure. This stage relies on interactions between AuCl4 – ions, water, and protonated P2VP chains. The second stage produces liquid droplets inside the film and near the substrate interface. The surface tensions of those liquid droplets at contact lines deform swollen P2VP films. Changing film thicknesses or substrate types alters craters’ lateral dimension and depth. The results indicate that film thicknesses and substrate interface energies influence the shape and dimension of liquid droplets on the substrate interface. The third stage determines morphologies of craters through interplays among capillary flows, Marangoni flows, and pinning/depinning events.
We have demonstrated the phase behavior of substrate-supported films of a symmetric weakly segregated polystyrene-
block
-poly (methyl methacrylate), P(S-
b
-MMA), block copolymer and its blends with ...homopolymer polystyrene (PS) at different compositions. Upon increasing the content of added PS in the blends, lamellae (L), perforated layers (PL), double gyroid (DG) and cylinders (C) are obtained in sequence for films. Among these nanodomains, PL and DG only exist in a narrow
PS
region (
PS
denotes the volume fraction of PS). At
PS
= 64%, tuning film thickness and annealing temperature can produce parallel PL or DG with {121}
DG
lattice planes being parallel to the substrate surface. The effects of annealing temperature and film thickness on the formation of PL and DG are examined. In thin films with
n
3 (
n
denotes the ratio of initial film thickness to inter-domain spacing), the PL phase solely exists regardless of temperature. However, for thick films with
n
6 and 10, thermal annealing at the most accessible temperature produces films containing both PL and DG of various fractions, but a low temperature tends to favor a greater fraction of PL. The PL phase becomes the only discernible phase if thick films are shortly annealed at 230 °C.
For P(S-
b
-MMA)/PS mixtures with
PS
= 64%, PL exists in thin films annealed at 230-270 °C. For thick films, thermal annealing at 245-270 °C produces both PL and DG of various fractions. PL becomes the only discernible phase in thick films annealed at 230 °C.
We have demonstrated the effects of different chain lengths on the phase behavior in films of binary blends of four different weight fractions in a weak segregation limit. The binary blends were ...composed of nearly symmetric polystyrene-block-poly(methyl methacrylate), PS-b-PMMA, and homo-polystyrenes (PS) of three different molecular weights (hereafter hPS2.8, hPS6, and hPS17). Films of two initial thicknesses were prepared by spin coating of the blends. After thermal annealing at 270 °C (1 h), a series of nanodomains, including perforated layers, double gyroid, cylinders, and spheres, were obtained in sequence as the volume fractions of PS increased in blend films. Perforated layers and double gyroid only exist in PS-b-PMMA-rich blend films, with hPS2.8/PS-b-PMMA blends overwhelmingly favoring perforated layers, regardless of film thickness. However, with a small amount of hPS6 chains, PS-b-PMMA-rich blends preferentially form hexagonally perforated layers in thin films but double gyroid in thick films; at the same composition, PS-b-PMMA-rich blends with hPS17 chains only form hexagonally perforated layers. Cylinders only formed in blend films of equal weight fractions of PS-b-PMMA and PS. The cylinders with hPS2.8 and hPS6 chains favor parallel orientation, but cylinders with hPS17 PS chains favor a mixed orientation. Spheres predominantly formed in PS-rich blend films, where four types of domain ordering (hexagonal packing, body-centered cubic (BCC), face-centered cubic (FCC), and short-range order) were obtained. For blend films prepared in the PS-rich regions, the four types of ordering depend on chain length and film thickness. The PS-b-PMMA blend films with hPS2.8 chains predominantly favor hexagonal packing of spheres for thin films but BCC packing of spheres for thick films. Under the same PS-rich region, the PS-b-PMMA blend films with hPS6 chains predominantly favor hexagonal arrays of spheres in thin films but FCC-packed arrays of spheres in thick films. The PS-b-PMMA blend films with hPS17 chains predominantly favor short-range-order spheres or a mixture of spheres and cylinders with no lattice packing. All of the above findings are explained by the correlation between the variations in chain length and alleviating packing frustration.
The Rape Of Nanking Chang, Iris
2012, 2009, 1997, 2014-03-11, 2007-12-31
eBook
"In December 1937, in what was then the capital of China, one of the most brutal massacres in the long annals of wartime barbarity occurred. The Japanese army swept into the ancient city of Nanking ...(Na".
Introduction Innate lymphoid cells (ILCs) are enriched at mucosal surfaces where they respond rapidly to environmental stimuli and contribute to both tissue inflammation and healing. Methods To gain ...insight into the role of ILCs in the pathology and recovery from COVID-19 infection, we employed a multi-omics approach consisting of Abseq and targeted mRNA sequencing to respectively probe the surface marker expression, transcriptional profile and heterogeneity of ILCs in peripheral blood of patients with COVID-19 compared with healthy controls. Results We found that the frequency of ILC1 and ILC2 cells was significantly increased in COVID-19 patients. Moreover, all ILC subsets displayed a significantly higher frequency of CD69-expressing cells, indicating a heightened state of activation. ILC2s from COVID-19 patients had the highest number of significantly differentially expressed (DE) genes. The most notable genes DE in COVID-19 vs healthy participants included a) genes associated with responses to virus infections and b) genes that support ILC self-proliferation, activation and homeostasis. In addition, differential gene regulatory network analysis revealed ILC-specific regulons and their interactions driving the differential gene expression in each ILC. Discussion Overall, this study provides mechanistic insights into the characteristics of ILC subsets activated during COVID-19 infection.
DNA methylation (DNAm) has been shown to play a role in mediating food allergy; however, the mechanism by which it does so is poorly understood. In this study, we used targeted next-generation ...bisulfite sequencing to evaluate DNAm levels in 125 targeted highly informative genomic regions containing 602 CpG sites on 70 immune-related genes to understand whether DNAm can differentiate peanut allergy (PA) versus nonallergy (NA). We found PA-associated DNAm signatures associated with 12 genes (7 potentially novel to food allergy, 3 associated with Th1/Th2, and 2 associated with innate immunity), as well as DNAm signature combinations with superior diagnostic potential compared with serum peanut-specific IgE for PA versus NA. Furthermore, we found that, following peanut protein stimulation, peripheral blood mononuclear cell (PBMCs) from PA participants showed increased production of cognate cytokines compared with NA participants. The varying responses between PA and NA participants may be associated with the interaction between the modification of DNAm and the interference of environment. Using Euclidean distance analysis, we found that the distances of methylation profile comprising 12 DNAm signatures between PA and NA pairs in monozygotic (MZ) twins were smaller than those in randomly paired genetically unrelated individuals, suggesting that PA-related DNAm signatures may be associated with genetic factors.
The development of carbon materials as highly efficient and durable substrates for surface-enhanced Raman scattering (SERS) is of great importance for realizing practical application of molecular ...sensing through Raman spectroscopy. In this report, we demonstrate the fabrication, by low-temperature pyrolysis, of high-quality, iron–nitrogen-doped carbon nanosheets and nanorods from spin-coated poly(4-vinylpyridine) (P4VP) polymer thin films and electrospun polymer nanofibers, respectively. As P4VP chains have functional pyridine rings available to bind with metal precursor ions through favorable interactions, iron (Fe) atoms can be incorporated into the carbon nanostructures with the aid of Fe(II) acetate during the synthesis. The incorporation of a metal salt can decrease the thermal stability of pyridinic groups so that the pyrolysis produces carbon nanostructures with high degree of graphitization and with iron- and nitrogen-doped species. The codopants in these carbon nanostructures introduce surface dipole moments, affect the DOS of valence bands, and decrease the work function. The electronic structure of carbon nanomaterials can be finely tuned to enable the vibronic coupling of the conduction band and valence band states of carbon nanostructures with the excited and ground states of the probed molecules of Rhodamine 6G and crystal violet. The vibronic coupling enables a superior enhancement in SERS with the detection limit concentration being as low as 10–7 M and the maximum enhancement factor being 3.8 × 104 through a charge transfer (CT) process. The polymer-templated carbon nanostructures offer great promise for the implementation of this system in a next-generation SERS substrate for molecular sensing.
A series of gold precursor solutions are prepared by dissolving HAuCl4 and its mixtures with K2CO3 of different contents in deionized (DI) water. Neat HAuCl4 predominately forms AuCl4 – ions in an ...aqueous solution. In the presence of K2CO3, AuCl4 – ions hydrolyze to form AuCl4–x (OH) x − complex ions. Increasing the content of K2CO3 in a gold precursor solution increases the content of AuCl4–x (OH) x − complex ions and decreases the content of AuCl4 – ions. Poly(4-vinyl pyridine) (P4VP) films of two different molecular weights are deposited on SiO x /Si by spin coating, by which the thicknesses are controlled by polymer weight fractions in butanol. Those P4VP films form periodic wrinkles when immersed in aqueous solutions, followed by drying. The surface wrinkling is induced by swelling pressure that overwhelms the mechanical property of the P4VP film. The periodicity and amplitude of wrinkles grown on the P4VP films strongly correlate with initial thickness, AuCl4 – ion content, and residual stress.
During the SARS-CoV-2 pandemic, novel and traditional vaccine strategies have been deployed globally. We investigated whether antibodies stimulated by mRNA vaccination (BNT162b2), including ...third-dose boosting, differ from those generated by infection or adenoviral (ChAdOx1-S and Gam-COVID-Vac) or inactivated viral (BBIBP-CorV) vaccines. We analyzed human lymph nodes after infection or mRNA vaccination for correlates of serological differences. Antibody breadth against viral variants is lower after infection compared with all vaccines evaluated but improves over several months. Viral variant infection elicits variant-specific antibodies, but prior mRNA vaccination imprints serological responses toward Wuhan-Hu-1 rather than variant antigens. In contrast to disrupted germinal centers (GCs) in lymph nodes during infection, mRNA vaccination stimulates robust GCs containing vaccine mRNA and spike antigen up to 8 weeks postvaccination in some cases. SARS-CoV-2 antibody specificity, breadth, and maturation are affected by imprinting from exposure history and distinct histological and antigenic contexts in infection compared with vaccination.
Display omitted
•Vaccination confers broader IgG binding of variant RBDs than SARS-CoV-2 infection•Imprinting from initial antigen exposures alters IgG responses to viral variants•Histology of mRNA vaccinee lymph nodes shows abundant GCs•Vaccine spike antigen and mRNA persist for weeks in lymph node GCs
Human antibody responses to SARS-CoV-2 differ between vaccination and infection, with mRNA vaccination inducing more productive lymph node GC responses and several vaccine types stimulating IgG antibodies capable of recognizing a broader range of viral variants.
PDF
