Atomic layer deposition (ALD) on single‐walled carbon nanotubes (SWNTs) can be achieved through physical surface modification using liquid‐phase pretreatment dispersion techniques. Al2O3 ALD on ...nonfunctionalized SWNTs produced isolated nodule growth. Ethanol and sodium dodecylsulfate (SDS) pretreatment methods were utilized to disperse and functionalize batches of nanotube powders. Ethanol‐based dispersion techniques provided hydroxylated surfaces that promoted continuous Al2O3 films on SWNT surfaces. The SDS method provided a dense nucleation site pattern that allowed for conformal Al2O3 film growth. Al2O3 ALD processes yielded growth rates of 0.13 nm/cycle, independent of the functionalization technique, at 450 K. X‐ray photoelectron spectroscopy was used to quantify the composition of the films, which were amorphous as deposited. A surfactant‐assisted ALD mechanism is proposed, which retains a physisorbed micelle structure as a template for the dense precursor nucleation site pattern. Liquid‐phase pretreatment was found to be an efficient mechanism to overcome attractive forces associated with nanoscale particle systems, and significantly reduced the size of nanotube bundles. The successful ALD on an individual suspended nanotube in other work was extended to the bulk coating of SWNT powders. This work demonstrates significant progress toward the goal of producing commercially viable SWNT‐based nanocomposite devices that incorporate bulk quantities of ALD‐functionalized nanotubes.
A rapid and accurate method for detection for common pathogenic bacteria in foodborne infections was established by using oligonucleotide array technology. Nylon membrane was used as the array ...support. A mutation region of the 23S rRNA gene was selected as the discrimination target from 14 species (genera) of bacteria causing foodborne infections and two unrelated bacterial species. A pair of universal primers was designed for PCR amplification of the 23S rRNA gene. Twenty-one species (genera)-specific oligonucleotide detection probes were synthesized and spotted onto the nylon membranes. The 23S rRNA gene amplification products of 14 species of pathogenic bacteria were hybridized to the oligonucleotide array. Hybridization results were analyzed with digoxigenin-linked enzyme reaction. Results indicated that nine species of pathogenic bacteria (
Escherichia coli,
Campylobacter jejuni,
Shigella dysenteriae,
Vibrio cholerae,
Vibrio parahaemolyticus,
Proteus vulgaris,
Bacillus cereus,
Listeria monocytogenes and
Clostridium botulinum) showed high sensitivity and specificity for the oligonucleotide array. Two other species (
Salmonella enterica and
Yersinia enterocolitica) gave weak cross-reaction with
E. coli, but the reaction did not affect their detection. After redesigning the probes, positive hybridization results were obtained with
Staphylococcus aureus, but not with
Clostridium perfringens and
Streptococcus pyogenes. The oligonucleotide array can also be applied to samples collected in clinical settings of foodborne infections. The superiority of oligonucleotide array over other tests lies on its rapidity, accuracy and efficiency in the diagnosis, treatment and control of foodborne infections.
The recovery of pure component spectra from multi-component mixtures is one of the most common analytical problems in the chemical sciences. In cases where separation of the unknown components is not ...possible, the problem is often intractable. In materials science research, X-ray diffraction (XRD) and particularly X-ray powder diffraction (XRPD) are perhaps the primary characterization tools. Recently, we introduced band-target entropy minimization (BTEM), an essentially model-free deconvolution technique, applicable to sets of unknown mixture samples and initially applied to liquid-phase characterization (Chew et al., Organometallics, 2002, 21, 1982–1990). In the present study, a set of 12 unknown inorganic powder mixtures were prepared and the XRPD patterns measured. BTEM was then applied. The analysis provided the right prediction that five components were present. Outstanding pure component XRD patterns were obtained for all five components (Pb
3(PO
4)
2, Pb
3(PO
4)
3Cl, ZrO
2, Pb(OH)
2, and PbO) present. These results have implications for a large variety of intrinsically inseparable multi-component mixtures encountered in material science research. These include un-reactive as well as reactive systems, and ex situ as well as in situ studies, involving organic, inorganic and even metallic/alloy components. Initial tests suggest that BTEM may be well suited for recovering the trace component diffraction patterns present and hence greatly aiding material characterization.
Hollow carbonated hydroxyapatite microspheres with mesoporous structure (HCHAs) have been fabricated by using calcium carbonated microspheres as sacrificial templates according to the following ...routes: (i) the in situ deposit of carbonated hydroxyapatite on the surfaces of CaCO3 microspheres by hydrothermal method and (ii) the removal of CaCO3 by chemical etching. The HCHAs consist of a hollow core and a mesoporous shell. Interestingly, the shell of the microspheres is constructed by carbonated hydroxyapatite nanoplates as building blocks. Moreover, these nanoplates are composed of many smaller nanoparticles with different crystal orientations, and the mesopores exist among these nanoparticles. The HCHAs exhibit the high drug-loading capacity and sustained drug release property, suggesting that the hierarchically porous microspheres have great potentials for bone-implantable drug-delivery applications.
•Hollow carbonated hydroxyapatite microspheres with mesoporous structure are prepared.•Calcium carbonated microspheres serve as sacrificial templates.•Carbonated hydroxyapatite microspheres consist of hollow core and mesoporous shell.•Carbonated hydroxyapatite microspheres exhibit high drug loading-release properties.
Entropy minimization is closely associated with pattern recognition. The present contribution uses a direct minimization of an entropy like function to solve the blind source separation problem for ...image reconstruction. The mixture patterns are decomposed using SVD and then global stochastic optimization is used to find the first irreducible image pattern. Further images are then subsequently reconstructed, by imposing a 2D correlation coefficient for dissimilarity to prevent repeated images, until all images are exhaustively enumerated. Three test cases are used, including (1) a set of three black and white texturally different photographs (2) a set of three RGB geometrically similar photographs and (3) an underdetermined problem involving an imbedded watermark. Cases 1 and 2 are easily solved with outstanding image quality. Both searches are conducted in an unsupervised manner—no a priori information is used. In Case 3, the watermark is enhanced after targeting the region for entropy minimization. The present results have a wide variety of applications, including image and spectroscopic analysis.
Filament channel (FC), a plasma volume where the magnetic field is primarily aligned with the polarity inversion line, is believed to be the pre-eruptive configuration of coronal mass ejections. ...Nevertheless, evidence for how the FC is formed is still elusive. In this paper, we present a detailed study on the build-up of a FC to understand its formation mechanism. The New Vacuum Solar Telescope of Yunnan Observatories and Optical and Near-Infrared Solar Eruption Tracer of Nanjing University, as well as the AIA and HMI on board Solar Dynamics Observatory are used to study the grow-up process of the FC. Furthermore, we reconstruct the non-linear force-free field (NLFFF) of the active region using the regularized Biot-Savart laws (RBSL) and magnetofrictional method to reveal three-dimension (3D) magnetic field properties of the FC. We find that partial filament materials are quickly transferred to longer magnetic field lines formed by small-scale magnetic reconnection, as evidenced by dot-like H{\alpha}/EUV brightenings and subsequent bidirectional outflow jets, as well as untwisting motions. The H{\alpha}/EUV bursts appear repeatedly at the same location and are closely associated with flux cancellation, which occurs between two small-scale opposite polarities and is driven by shearing and converging motions. The 3D NLFFF model reveals that the reconnection takes place in a hyperbolic flux tube that is located above the flux cancellation site and below the FC. The FC is gradually built up toward a twisted flux rope via series of small-scale reconnection events that occur intermittently prior to the eruption.
The number of elderly in the world is increasing rapidly, especially in China. The prevalence of dementia among elderly was investigated in a community of Sheshan town, located in the Southwest ...suburb of Shanghai, China. Face-to-face interviews were conducted to collect relevant information with prepared questionnaires. The Chinese version of the Mini-Mental Status Examination was used to screen subjects with cognitive impairment (CI). Physical examinations and neuropsychological assessments were carried out. Dementia and its major subtypes, Alzheimer's disease (AD) and vascular dementia (VaD), were diagnosed by senior neurologists according to relevant diagnostic criteria. In addition, magnetic resonance imaging and EEG (with P300) were performed for a number of cases with AD or VaD. There were 1,472 participants (666 males and 806 females) aged 60 years and over in the study. A total of 167 subjects with CI were screened. Among them, dementia was recognized in 79 cases with a prevalence of 5.37% (95% confidence intervals: 4.22%-6.52%). The diagnosis of AD was made for 53 cases (16 males and 37 females) with a prevalence of 3.60% (95% confidence intervals: 2.65%-4.55%), and VaD for 21 cases (5 males and 16 females) with a prevalence of 1.43% (95% confidence intervals: 0.82%-2.03%); while the ratio of AD to VaD was 2.52. The prevalence rates of dementia among elderly from our study are higher than that previously reported from China, but in line with that reported from most world regions. A nationwide survey and surveillance system on the prevalence of dementia is recommended.
Summary A role for protein kinase C (PKC)‐α has been implicated in the growth of mouse hair. Topical application of PKC activators, hair plucking, allergic contact dermatitis and skin irritation can ...all enhance growth of mouse hair, and a significant increase in PKC‐α level in whole mouse skin in mature anagen has been demonstrated in these processes. Overexpression of PKC‐α in anagen hair follicles has also been reported in natural growth of mouse hair. It is known that overexpression of PKC‐α is associated with the acceleration of cell growth. Therefore, we postulated that overexpression of PKC‐α in mature anagen may relate to enhancement of hair growth. The distribution of PKC‐α in hair follicles during induced growth of mouse hair has not previously been studied. In this study, hair growth in C57BL/6 mice was induced by plucking the telogen hairs on one side of the back. The undepilated contralateral side served as a control. Expression of PKC‐α in hair follicles during the hair growth cycle induced was evaluated by immunohistochemistry using cryosections and a specific polyclonal anti‐PKC‐α immunoglobulin G (IgG) antibody. No PKC‐α was detected in telogen hair follicles or in the hair follicles at 1 day post‐depilation, when the induced hair cycle was in early anagen. At 4 days after plucking, when the induced hair cycle was in mid‐anagen, intense staining for PKC‐α was found in hair papillae. At 10 and 17 days after depilation, when the induced hair cycle was in mature anagen and early catagen, respectively, all outer root sheath (ORS) cells and outer connective sheaths of hair follicles were stained positive. Because no PKC‐α was detected in telogen hair follicles in this study, down‐regulation of PKC‐α in early anagen could not be observed. However, consistent with our previous findings, overexpression of PKC‐α was found in mid‐anagen and mature anagen. As overexpression of PKC‐α has been shown to be associated with acceleration of cell growth, our results support the notion that PKC‐α may play an important role in growth of hair follicle cells in induced growth of hair. As PKC levels are known to increase in hyperglycaemia, overexpressed PKC‐α in mature anagen hair follicles may be related to the putative function of the ORS in mobilizing glycogen stores for anagen growth.
Two-dimensional magnets could potentially revolutionize information technology, but their potential application to cooling technology and magnetocaloric effect (MCE) in a material down to the ...monolayer limit remain unexplored. Herein, we reveal through multiscale calculations the existence of giant MCE and its strain tunability in monolayer magnets such as CrX\(_3\) (X=F, Cl, Br, I), CrAX (A=O, S, Se; X=F, Cl, Br, I), and Fe\(_3\)GeTe\(_2\). The maximum adiabatic temperature change (\(\Delta T_\text{ad}^\text{max}\)), maximum isothermal magnetic entropy change, and specific cooling power in monolayer CrF\(_3\) are found as high as 11 K, 35 \(\mu\)Jm\(^{-2}\)K\(^{-1}\), and 3.5 nWcm\(^{-2}\) under a magnetic field of 5 T, respectively. A 2% biaxial and 5% \(a\)-axis uniaxial compressive strain can remarkably increase \(\Delta T_\text{ad}^\text{max}\) of CrCl\(_3\) and CrOF by 230% and 37% (up to 15.3 and 6.0 K), respectively. It is found that large net magnetic moment per unit area favors improved MCE. These findings advocate the giant-MCE monolayer magnets, opening new opportunities for magnetic cooling at nanoscale.
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