Peroxisome Proliferator-activated Receptor-γ Deficiency Exacerbates Fibrotic Response to Mycobacteria Peptide in Murine Sarcoidosis Model.

We established a murine model of multiwall carbon nanotube (MWCNT)-elicited chronic granulomatous disease that bears similarities to human sarcoidosis pathology, including alveolar macrophage deficiency of peroxisome proliferator-activated receptor γ (PPARγ). Because lymphocyte reactivity to mycobacterial antigens has been reported in sarcoidosis, we hypothesized that addition of mycobacterial ESAT-6 (early secreted antigenic target protein 6) to MWCNT might exacerbate pulmonary granulomatous pathology. MWCNTs with or without ESAT-6 peptide 14 were instilled by the oropharyngeal route into macrophage-specific PPARγ-knockout (KO) or wild-type mice. Control animals received PBS or ESAT-6. Lung tissues, BAL cells, and BAL fluid were evaluated 60 days after instillation. PPARγ-KO mice receiving MWCNT + ESAT-6 had increased granulomas and significantly elevated fibrosis (trichrome staining) compared with wild-type mice or PPARγ-KO mice that received only MWCNT. Immunostaining of lung tissues revealed elevated fibronectin and Siglec F expression on CD11c+ infiltrating alveolar macrophages in the presence of MWCNT + ESAT-6 compared with MWCNT alone. Analyses of BAL fluid proteins indicated increased levels of transforming growth factor (TGF)-ß and the TGF-ß pathway mediator IL-13 in PPARγ-KO mice that received MWCNT + ESAT-6 compared with wild-type or PPARγ-KO mice that received MWCNT. Similarly, mRNA levels of matrix metalloproteinase 9, another requisite factor for TGF-ß production, was elevated in PPARγ-KO mice by MWCNT + ESAT-6. Analysis of ESAT-6 in lung tissues by mass spectrometry revealed ESAT-6 retention in lung tissues of PPARγ-KO but not wild-type mice. These data indicate that PPARγ deficiency promotes pulmonary ESAT-6 retention, exacerbates macrophage responses to MWCNT + ESAT-6, and intensifies pulmonary fibrosis. The present findings suggest that the model may facilitate understanding of the effects of environmental factors on sarcoidosis-associated pulmonary fibrosis.

Lanthanum-Doped Hafnium Oxide: A Robust Ferroelectric Material.

Recently simulation groups have reported the lanthanide series elements as the dopants that have the strongest effect on the stabilization of the ferroelectric non-centrosymmetric orthorhombic phase in hafnium oxide. This finding confirms experimental results for lanthanum and gadolinium showing the highest remanent polarization values of all hafnia-based ferroelectric films until now. However, no comprehensive overview that links structural properties to the electrical performance of the films in detail is available for lanthanide-doped hafnia. La:HfO2 appears to be a material with a broad window of process parameters, and accordingly, by optimization of the La content in the layer, it is possible to improve the performance of the material significantly. Variations of the La concentration leads to changes in the crystallographic structure in the bulk of the films and at the interfaces to the electrode materials, which impacts the spontaneous polarization, internal bias fields, and with this the field cycling behavior of the capacitor structure. Characterization results are compared to other dopants like Si, Al, and Gd to validate the advantages of the material in applications such as semiconductor memory devices.

Time-of-flight-secondary ion mass spectrometry method development for high-sensitivity analysis of acid dyes in nylon fibers.

A minimally destructive technique for the determination of dyes in finished fibers provides an important tool for crime scene and other forensic investigations. The analytical power and the minimal sample consumption of time-of-flight-secondary ion mass spectrometric (TOF-SIMS) analysis provides the ability to obtain definitive molecular and elemental information relevant to fiber identification, including identification of dyes, from a very small volume of sample. For both fiber surface analysis and, with the aid of cryomicrotomy, fiber cross-section analysis, TOF-SIMS was used to identify various dyes in finished textile fibers. The analysis of C.I. Acid Blue 25 in nylon is presented as a representative example. The molecular ion of C.I. Acid Blue 25 with lower than 3% on weight-of-fiber (owf) dye loading cannot be identified on dyed nylon surfaces by TOF-SIMS using a Bi(3)(+) primary ion beam. Sputtering with C(60)(+) provided the ability to remove surface contamination as well as at least partially remove Bi-induced damage, resulting in a greatly improved signal-to-noise ratio for the Acid Blue 25 molecular ion. The use of C(60)(+) for damage removal in a cyclic manner along with Bi for data acquisition provided the ability to unambiguously identify Acid Blue 25 via its molecular ion at a concentration of 0.1% owf from both fiber surfaces and cross sections.

Nonwoven Membranes with Infrared Light-Controlled Permeability.

This study presents the development of the first composite nonwoven fiber mats (NWFs) with infrared light-controlled permeability. The membranes were prepared by coating polypropylene NWFs with a photothermal layer of poly(N-isopropylacrylamide) (PNIPAm)-based microgels impregnated with graphene oxide nanoparticles (GONPs). This design enables "photothermal smart-gating" using light dosage as remote control of the membrane's permeability to electrolytes. Upon exposure to infrared light, the GONPs trigger a rapid local increase in temperature, which contracts the PNIPAm-based microgels lodged in the pore space of the NWFs. The contraction of the microgels can be reverted by cooling from the surrounding aqueous environment. The efficient conversion of infrared light into localized heat by GONPs coupled with the phase transition of the microgels above the lower critical solution temperature (LCST) of PNIPAm provide effective control over the effective porosity, and thus the permeability, of the membrane. The material design parameters, namely the monomer composition of the microgels and the GONP-to-microgel ratio, enable tuning the permeability shift in response to IR light; control NWFs coated with GONP-free microgels displayed thermal responsiveness only, whereas native NWFs showed no smart-gating behavior at all. This technology shows potential toward processing temperature-sensitive bioactive ingredients or remote-controlled bioreactors.

Chemical and spatial differentiation of syringyl and guaiacyl lignins in poplar wood via time-of-flight secondary ion mass spectrometry.

As a major component in plant cell walls, lignin is an important factor in numerous industrial processes, especially in wood saccharification and fermentation to biofuels. The ability to chemically differentiate and spatially locate lignins in wood cell structures provides an important contribution to the effort to improve these processes. The spatial distribution of the syringyl (S) and guaiacyl (G) lignins, both over larger regions and within a single cell wall, on poplar ( Populus trichocarpa ) wood cross-sections was determined via time-of-flight secondary ion mass spectrometry (ToF-SIMS). This is the first time that direct chemically specific mass spectrometric mapping has been employed to elucidate the spatial distribution of S and G lignins. In agreement with results obtained by UV microscopy, ToF-SIMS images clearly show that the guaiacyl lignin is predominantly located in the vessel cell walls of poplar wood while syringyl lignin is mainly located in the fiber cell walls. The G/S ratio in vessel cell walls was determined to be approximately twice that found in fiber cell walls. A combination of Bi ToF-SIMS spectral image acquisition and C(60) sputtering provided the ability to attain the combination of spatial resolution and signal-to-noise necessary to determine the distribution of S and G lignins in a single cell wall. By this technique, it was possible to demonstrate that more guaiacyl lignin is located in the middle lamella layer and more syringyl lignin is located in the inner cell wall area.

Formation of multilayer ultrathin assemblies using chemical lithography.

Ultrathin complex multilayer structures have many potential applications in molecular and organic electronics, sensing, biotechnology and other areas. Reported here is a method by which to construct multifunctional, multilayer, patterned structures, using alkanethiolate SAMs adsorbed on Au, UV photopatterning, and chemoselective covalent bond formation. We demonstrate that amide coupling is efficient for producing multilayer structures on -COOH-terminated SAMs, while oxime coupling is efficient for producing multilayer structures on -CHO-terminated SAMs. Reaction yields obtained are approximately 67% and approximately 84% for the coupling of the first layer (bilayer formation) for amide and oxime coupling, respectively. Subsequent adlayer formation occurs with approximately 100% yield in both cases. The resulting adlayers are chemically robust and are suitable for subsequent chemical processing. Finally, both chemistries are used to produce a complex multilayer structure atop a UV photopatterned SAM. The resulting construct is well-defined and has the same lateral resolution as the photopatterned SAM substrate. The method demonstrated here is synthetically flexible and allows for the assembly of functionally complex surfaces and, in principle, the incorporation of biomolecules and metals.

Comparison of chemical lithography using alkanethiolate self-assembled monolayers on GaAs (001) and Au.

We have investigated the efficiency of bifunctional pattern formation in alkanethiolate self-assembled monolayers (SAMs) adsorbed on GaAs (001) and Au, using time-of-flight secondary ion mass spectrometry. Two patterning techniques were employed: electron beam lithography and UV photopatterning. Previous work has always assumed that complete degradation of the SAM was necessary for the formation of well-defined multifunctional patterned surfaces, requiring large electron doses or long UV irradiation times. We demonstrate that well-defined multifunctional patterned surfaces can be produced on GaAs (001) with only partial degradation of the SAM, allowing greatly reduced electron beam doses and UV irradiation times to be used. Using electron beam lithography we observe that sharp well-defined patterns can form after an electron dose as low as 450 microC cm(-2). We also demonstrate that only 50% of the monolayer must be photooxidized in UV photopatterning, reducing the exposure time needed by a factor of 3. In contrast, patterning of alkanethiolate SAMs adsorbed on Au requires much higher electron doses (> or = 1250 microC cm(-2)) and photooxidation times (2 h). The substantial differences observed on these two substrates appear to arise from differences in the SAM structure on GaAs and Au. These results suggest that alkanethiolate SAM resists may be a suitable technology for nanometer scale lithography of GaAs and possibly other semiconductors.

Optical and electrical properties of all-inorganic Cs2AgBiBr6 double perovskite single crystals.

In this work, we explored the possibility of using Cs2AgBiBr6, a double perovskite crystal, for radiation detection. Cs2AgBiBr6 crystals were grown using the solution growth technique. The resistivity of the as-grown Cs2AgBiBr6 crystal is larger than 1010 Ω cm, which is high enough to ensure low leakage current for fabrication of semiconductor radiation detectors. Using the temperature-dependent resistivity measurements, we estimated that the Fermi level is at 0.788 eV above the valence band and the material is a p-type semiconductor. From the low-temperature cathodoluminescence measurements, two near band gap energies at 1.917 eV and 2.054 eV were revealed.

Time-of-flight secondary ion mass spectrometry, fluorescence microscopy and scanning electron microscopy: combined tools for monitoring the process of patterning and layer-by-layer assembly of synthetic and biological materials.

We have employed time-of-flight secondary ion mass spectrometry (TOF SIMS), fluorescence microscopy and scanning electron microscopy (SEM) to monitor the immobilization of biotinylated shell-crosslinked nanoparticles (SCKs) on biotin/streptavidin-functionalized, UV-photopatterned self-assembled monolayers (SAMs). TOF SIMS and fluorescence microscopy images showed that the streptavidin was immobilized primarily in the biotin-functionalized SAM areas. Biotinylated SCKs underwent both streptavidin-biotin recognition and electrostatic interactions to the underlying substrate. Upon adsorption, the biotinylated SCKs deformed significantly; their cross-sectional diameter increased by approximately 36% from 65+/-7 nm to 90+/-2 nm. Using the SCK contact area, we estimate that one SCK was bound between one and five streptavidin proteins. These data suggest that functionalized SCKs can be employed as biomolecule mimics to investigate the factors that control biomolecule adsorption on functionalized surfaces.

Imaging and quantitative analysis of insecticide in mosquito net fibers using Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS).

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) analysis was used to qualitatively and quantitatively assess the distribution of permethrin insecticide on the surfaces and interiors of Olyset long-lasting insecticidal net (LLIN) fibers. Total insecticide content in LLINs has been established using many analytical methods. However, it is important to quantify the bioavailable portion residing on the fiber surfaces for incorporated LLINs. ToF-SIMS is a very surface sensitive technique and can directly image the spatial distribution of permethrin insecticide on the surface of Olyset fibers. Surface permethrin appeared as patchy deposits which were easily removed by acetone and reappeared after several days as interior permethrin migrated (bloomed) from the fiber interior. After a wash/incubation cycle, permethrin deposits were more diffuse and less concentrated than those on the as-received fibers. ToF-SIMS is particularly sensitive to detect the Cl- ion, which is the characteristic ion of permethrin. Ion implantation and quantification of dopants using SIMS is well established in the semiconductor industry. In this study, quantitative depth profiling was carried out using 35Cl- ion implantation to correlate secondary ion yield with permethrin concentration, yielding a limit of detection of 0.051 wt% for permethrin. In some cases, surface concentration differed greatly from the fiber interior (>1 µm below the surface). Two- and three-dimensional mapping of Cl at sub-micrometer resolution showed permethrin to be dissolved throughout the fiber, with about 2 vol% residing in disperse, high-concentration domains. This suggests that these fibers fall into the class of monolithic sustained-release devices. It is expected that ToF-SIMS can be a valuable tool to provide insight into the insecticide release behavior of other LLIN products, both current and future.

Significantly Increasing the Ductility of High Performance Polymer Semiconductors through Polymer Blending.

Polymer semiconductors based on donor-acceptor monomers have recently resulted in significant gains in field effect mobility in organic thin film transistors (OTFTs). These polymers incorporate fused aromatic rings and have been designed to have stiff planar backbones, resulting in strong intermolecular interactions, which subsequently result in stiff and brittle films. The complex synthesis typically required for these materials may also result in increased production costs. Thus, the development of methods to improve mechanical plasticity while lowering material consumption during fabrication will significantly improve opportunities for adoption in flexible and stretchable electronics. To achieve these goals, we consider blending a brittle donor-acceptor polymer, poly[4-(4,4-dihexadecyl-4H-cyclopenta[1,2-b:5,4-b']dithiophen-2-yl)-alt-[1,2,5]thiadiazolo[3,4-c]pyridine] (PCDTPT), with ductile poly(3-hexylthiophene). We found that the ductility of the blend films is significantly improved compared to that of neat PCDTPT films, and when the blend film is employed in an OTFT, the performance is largely maintained. The ability to maintain charge transport character is due to vertical segregation within the blend, while the improved ductility is due to intermixing of the polymers throughout the film thickness. Importantly, the application of large strains to the ductile films is shown to orient both polymers, which further increases charge carrier mobility. These results highlight a processing approach to achieve high performance polymer OTFTs that are electrically and mechanically optimized.

The cationization mechanism study of novel oligo (p-phenyleneethynylene)s.

Two series of new oligo(p-phenyleneethynylene)s (OPEs) O1-O4 and O5-O8, which have been proven to be one of the chief classes of molecules mainly used as the wires and other potential backbones of molecular electronic devices, have been synthesized by stepwise synthetic approach. The characterization of these oligomers was performed on MALDI TOF MS. Different cationization salts have been applied to investigate the ionization processes of these series of oligomers under MALDI conditions. The experimental results show that these oligomers display a strong tendency to undergo radical cationization and varied ionization efficiency with different cationization agents attributable to their difference in cationic diameters. Furthermore, we found that these two series of oligomers differed in ionization properties because of their different end-groups even when the same cationization agent was used.

UV photooxidation and photopatterning of alkanethiolate self-assembled monolayers (SAMs) on GaAs (001).

We have investigated the photooxidation of alkanethiolate self-assembled monoalyers (SAMs) adsorbed on GaAs (001) using time-of-flight secondary ion mass spectrometry. Both -CH3- and -COOH-terminated SAMs undergo photoreaction to form sulfonated species upon exposure to UV light from a 500 W Hg arc lamp (lambda = 280-440 nm) in the presence of oxygen. In contrast to SAMs adsorbed on metals, the photooxidation of octadecanethiol adsorbed on GaAs can be fit to two first-order reactions: a fast initial reaction followed by a second slower reaction ( approximately 6 times slower). For SAMs with shorter alkyl chain lengths, the photooxidation process is can be fit to a single first-order reaction. Using the optimal photooxidation time, we also demonstrate that SAMs can be successfully UV photopatterned on GaAs substrates producing sharp, well-defined patterns.

Dependence of patterned binary alkanethiolate self-assembled monolayers on "UV-photopatterning" conditions and evolution with time, terminal group, and methylene chain length.

We have investigated the mechanism of UV photopatterning of binary alkanethiolate self-assembled monolayers (SAMs) adsorbed on Au(111) using time-of-flight secondary ion mass spectrometry. The SAMs were photopatterned using a 500 W Hg arc lamp. The patterning process is strongly dependent on the wavelength of light used. When an unfiltered arc lamp is employed, IR light impinges on the sample and causes considerable sample heating. Methyl-terminated SAMs with less than 14 carbons in the chain melt at the temperatures reached and become very disordered and so can be easily displaced by a second SAM. This leads to significant pattern degradation ("erosion"). SAMs with greater than 14 carbons undergo a transition to an incommensurate phase but remain stable on the surface, and the pattern is retained. When the IR light is filtered out, a different behavior is observed. UV-photopatterned methyl-terminated SAMs with 10 carbons in the chain are stable. Terminal group interactions, such as H-bonding, provide extra stabilization energy during photopatterning, so some patterns with shorter carbon chains may also be stable. The displacement of the photooxidized SAMs on the patterned surface follows kinetics similar to that of large-area SAM formation.

Toward molecular electronic circuitry: selective deposition of metals on patterned self-assembled monolayer surfaces.

We have developed a simple, robust method by which to construct complex two-dimensional structures based on controlling interfacial chemistry. Our approach is to employ UV-photopatterning and the reaction of vapor-deposited metals with self-assembled monolayers. To demonstrate the method, we have selectively vapor-deposited Mg on a patterned -CH3/-COOH-terminated alkanethiolate surface. The deposited metal penetrates through the -CH3 SAM to the Au/S interface while reacting with and accumulating on top of the -COOH SAM. This work has important applications in molecular/organic electronics, sensing, and other technologies. Our method has many advantages: it is extensible to many different materials, easily parallelized, affords precise nanoscale placement, and is fully compatible with photolithography.

AFM characterization of nanoscale ribbons grown from a series of oligo(p-phenyleneethynylene) derivatives.

The key to optimizing the properties of molecular scale wires lies in understanding and controlling the solid-state morphologies. This paper examines the influence of oligomer chain length, solvent, and concentration on the formation of nanoscale ribbons on mica substrates from solutions of oligo(p-phenyleneethynylene)s (OPEs) with hexyloxy side chains and thioacetyl end groups. The OPEs are of different molecular chain lengths, in which the numbers ofp-dihexyloxyphenyleneethynylene repeat units, n, are 1, 3, 5, and 7, respectively, with their two ends capped with 4-thioacetylphenyl alligator groups. The atomic force microscope (AFM) is employed to investigate the thin film morphology and study the self-assembled organizations. Solvent and concentration are found to exert a strong influence on thin film morphology. Under suitable conditions, OPEs with 7 p-dihexyloxyphenyleneethynylene repeat units are driven to form micrometer-long nanoribbons, oriented preferably along the 3-fold symmetry axes of the mica substrate. The cross section of the nanoribbons is composed of 7 molecules as evaluated by AFM characterization. On the other hand, oligomers with shorter chain lengths (n = 1, 3, and 5) produce thin films featuring globular nanoaggregates, chains consisting of elongated grains, and rods, respectively. Plausible reasons for the variation in thin film morphology are discussed, based on the results obtained from investigation of oligomer chain length, solvent, and concentration effects. A subtle balance among molecular size and physicochemical properties of solute molecules, solvent molecules, and substrate is crucial for the formation of desired structures. Among them, oligomer chain length plays a key role in thin film morphology, and the critical number of repeat units in OPE/poly(p-phenyleneethynylene) molecules for the formation of nanoribbon structures with a molecular cross section is supposed to be 8 or 9.