In situ identification of crystal facet-mediated chemical reactions on tetrahexahedral gold nanocrystals using surface-enhanced Raman spectroscopy

National Basic Research Program of China [2010CB934700]; National Science Foundation of China [50725208, 20973019, 51002007, 21303006]Direct monitoring of a metal-catalyzed reaction by surface-enhanced Raman scattering (SERS) is always a challenging issue as it needs bifunctional metal structures that have plasmonic properties and also act as catalysts. Here we demonstrate that the tetrahexahedral (THH) gold nanocrystals (Au NCs) with exposed {520} facets give highly enhanced Raman signals from molecules at the interface, permitting in situ observation of chemical transformation from para-aminothiophenol (PATP) to 4,4'-dimercaptoazobenzene (DMAB). The origin of the intense SERS signals of DMAB is carefully investigated based on the comparison of the SERS spectra of PATP obtained with both the THH Au NCs and the Au nanospheres with the exposed {111} facets. It is elucidated that the high-index {520} facet rather than the localized surface plasmons of the THH Au NCs plays a key role in producing a high yield of the product DMAB which is accompanied by the selective enhancement of the characteristic Raman signals

Altered spontaneous brain activity during dobutamine challenge in healthy young adults: A resting-state functional magnetic resonance imaging study

IntroductionThere is a growing interest in exploring brain-heart interactions. However, few studies have investigated the brain-heart interactions in healthy populations, especially in healthy young adults. The aim of this study was to explore the association between cardiovascular and spontaneous brain activities during dobutamine infusion in healthy young adults.MethodsForty-eight right-handed healthy participants (43 males and 5 females, range: 22–34 years) underwent vital signs monitoring, cognitive function assessment and brain MRI scans. Cardiovascular function was evaluated using blood pressure and heart rate, while two resting-state functional magnetic resonance imaging (rs-fMRI) methods—regional homogeneity (ReHo) and amplitude of low-frequency fluctuation (ALFF)—were used together to reflect the local neural activity of the brain. Logistic regression was used to model the association between brain and heart.ResultsResults showed that blood pressure and heart rate significantly increased after dobutamine infusion, and the performance in brain functional activity was the decrease in ReHo in the left gyrus rectus and in ALFF in the left frontal superior orbital. The results of logistic regression showed that the difference of diastolic blood pressure (DBP) had significant positive relationship with the degree of change of ReHo, while the difference of systolic blood pressure (SBP) had significant negative impact on the degree of change in ALFF.DiscussionThese findings suggest that the brain-heart interactions exist in healthy young adults under acute cardiovascular alterations, and more attention should be paid to blood pressure changes in young adults and assessment of frontal lobe function to provide them with more effective health protection management

Influence of Microbubble on Fine Wolframite Flotation

The recovery of fine wolframite is low when using traditional flotation that does not use a microbubble. In this study, a microbubble was introduced into the fine wolframite flotation system; −20 μm wolframite was used as an experiment sample and octyl hydroxamic acid as the collector. The recovery of microbubble flotation reached 84.07%, which is about 12.04% higher than that of traditional flotation. A single-factor flotation experiment, high-speed camera analysis, and SEM (Scanning Electron Microscopy) analysis were used to study the influence of microbubbles on the flotation of fine wolframite. The results show that fine wolframite will more easily agglomerate under the action of microbubbles. The octyl hydroxamic acid adsorbed on the surface of wolframite treated with microbubbles is denser and more abundant

Data from: Mechanism of Ca2+, Mg2+ and Fe3+ in fine cassiterite flotation using octanohydroxamic acid

The existence of metal ion should not be ignored in both hydrometallurgy and flotation. In this study, the effects of Ca2+, Mg2+ and Fe3+ on the flotation performance of cassiterite using octanohydroxamic acid (OHA) as the collector were investigated by the micro-flotation tests, X-ray photoelectron spectroscopy (XPS), fourier transform infrared spectroscopy (FTIR), contact angle, zeta (ζ) potential measurements and atomic force microscopy (AFM) imaging. The results of the flotation and contact angle experiments showed that the addition of Ca2+, Mg2+ and Fe3+ significantly decreased both the recovery and contact angle of cassiterite within pH ranged from 6.0 to 12.0 in the presence of OHA collector. ζ–potential measurements, solution chemistry analysis and FTIR measurements indicated that the flotation recovery of the cassiterite declined due to the CaOH+, MgOH+ and Fe(OH)3 sites on the cassiterite surface. XPS results indicated that the chemisorption of OHA on cassiterite surface and its adsorption combined with calcium ions effects finally changed the chemical properties of cassiterite surface. The AFM images also revealed that new species Fe(OH)3 of Fe3+ formed and adsorbed on the cassiterite surface at pH of 9.0. The adsorption of Fe(OH)3 reduced the adsorption of OHA on the cassiterite surface, thus the hydrophobicity of cassiterite was deteriorated

Data from: Mechanism of Ca2+, Mg2+ and Fe3+ in fine cassiterite flotation using octanohydroxamic acid

The existence of metal ion should not be ignored in both hydrometallurgy and flotation. In this study, the effects of Ca2+, Mg2+ and Fe3+ on the flotation performance of cassiterite using octanohydroxamic acid (OHA) as the collector were investigated by the micro-flotation tests, X-ray photoelectron spectroscopy (XPS), fourier transform infrared spectroscopy (FTIR), contact angle, zeta (ζ) potential measurements and atomic force microscopy (AFM) imaging. The results of the flotation and contact angle experiments showed that the addition of Ca2+, Mg2+ and Fe3+ significantly decreased both the recovery and contact angle of cassiterite within pH ranged from 6.0 to 12.0 in the presence of OHA collector. ζ–potential measurements, solution chemistry analysis and FTIR measurements indicated that the flotation recovery of the cassiterite declined due to the CaOH+, MgOH+ and Fe(OH)3 sites on the cassiterite surface. XPS results indicated that the chemisorption of OHA on cassiterite surface and its adsorption combined with calcium ions effects finally changed the chemical properties of cassiterite surface. The AFM images also revealed that new species Fe(OH)3 of Fe3+ formed and adsorbed on the cassiterite surface at pH of 9.0. The adsorption of Fe(OH)3 reduced the adsorption of OHA on the cassiterite surface, thus the hydrophobicity of cassiterite was deteriorated

Stiff micelle-crosslinked hyaluronate hydrogels with low swelling for potential cartilage repair

Stiff micelle-crosslinked hyaluronate hydrogels with low swelling for potential cartilage repai

Effects of alkyl ether amine and calcium ions on fine quartz flotation and its guidance for upgrading vanadium from stone coal

Great progress has been made in reverse flotation of fine quartz, especially many new reagents were proved their excellent effects. However, the influences of complex flotation system on fine quartz flotation still need to be scrutinized. In this study, alkyl ether amine (Flotigam EDA-C from Clariant) was used as a collector for the flotation of quartz. It shows better collectability for the flotation of quartz at about pH 10.0 (±0.2). The adsorption mechanism of EDA-C on quartz and the influence of calcium ions on the flotation of quartz were investigated by adsorption tests, zeta-potential measurements, FTIR spectra measurements, X-ray photoelectron spectroscopic and atomic force microscopy imaging. Results show that EDA-C adsorbs on the quartz surface in physical adsorption with no new products, changing its zeta potentials and increasing its hydrophobicity. Calcium ion concentration of 20 mg/L, 40 mg/L, 60 mg/L and 1 g/L can inhibit the quartz surface strongly and decrease its recovery sharply. Inhibition action of 2 g/L Ca decreased, even disappeared when the collector concentration increased to 90 mg/L. Calcium ions changed the chemical environment of Si atoms and O1s on the quartz surface. After positively charged CaOH adsorbed on quartz surface, the amount of EDA-C adsorbed on quartz surface and the recovery decreased. It was greatly inspired to explore quartz separation application from these results

Single cell migration dynamics mediated by geometric confinement.

The migration dynamics of cells plays a key role in tissue engineering and regenerative medicine. Previous studies mostly focus on regulating stem cell fate and phenotype by biophysical cues. In contrast, less is known about how the geometric cues mediate the migration dynamics of cells. Here, we fabricate graphene oxide (GO) microstripes on cell non-adhesive PEG substrate by using micromolding in capillary (MIMIC) method. Such micropatterns with alternating cell adhesion and cell resistance enable an effective control of selective adhesion and migration of single cells. The sharp contrast in cell adhesion minimizes the invasion of cells into the PEG patterns, and thereby strongly confines the cells on GO microstripes. As a result, the cells are forced to adapt highly polarized, elongated, and oriented geometry to fit the patterns. A series of pattern widths have been fabricated to modulate the extent of cell deformation and polarization. Under strong confinement, the cytoskeleton contractility, intracellular traction, and actin filament elongation are highly promoted, which result in enhanced cell migration along the patterns. This work provides an important insight into developing combinatorial graphene-based patterns for the control of cell migration dynamics, which is of great significance for tissue engineering and regenerative medicine

The histological characteristics, age-related thickness change of skin, and expression of the HSPs in the skin during hair cycle in yak (Bos grunniens).

OBJECTIVE:This experiment was conducted to study the histological characteristics, age-related thickness changes, and expression of HSPs in the skin of yak. METHODS:A total of 20 yaks (10 males and 10 females) were used. Different regions of the normal skin of three different ages (newborn, half-year-old and adult) of yaks were harvested for histological study and thickness measurement. Biopsy samples were taken from the scapula regions of the skin from the same five approximately 1-year-old yaks during the hair cycle (telogen, anagen and catagen). RT-PCR, western blot and immunohistochemistry methods using the mRNA and protein levels were used to detect the expression of HSP27, HSP70 and HSP90. RT-PCR method was used to detect the mRNA expression of CGI-58 and KDF1. The IPP6.0 software was used to analyze the immunohistochemistry and measure the thickness of the skin. RESULTS:The general histological structure of hairy yak skin was similar to other domestic mammals. The unique features included prominent cutaneous vascular plexuses, underdeveloped sweat glands, a large number of nasolabial glands in the nasolabial plate, and hair follicle groups composed of one primary follicle and several secondary follicles. The skin, epidermis and dermis thickness did vary significantly between different body regions and different ages. The thickness of the skin, epidermis and dermis increased from newborn to adult in yaks. Yak skin thickness decreased from dorsally to ventrally on the trunk. The skin on the lateral surface was thicker than the skin on the medial surface on the limbs. HSP27, HSP70 and HSP90 showed different expression patterns during the hair cycle using RT-PCR, western blot and immunohistochemistry methods. The expression of HSP27 mRNA and protein in the anagen stage was the highest, followed by the catagen stage, and the expression in the telogen stage was the lowest. The expression of HSP70 mRNA and protein in the telogen stage was the highest, followed by the anagen stage, and the expression in the catagen stage was the lowest. The expression of HSP90 mRNA and protein in the anagen stage was the highest, followed by the telogen stage, and the expression in the catagen stage was the lowest. HSPs were mainly expressed in the outer root sheath of hair follicle during the hair cycle, also expressed in epidermis, sebaceous gland and sweat gland in the skin of Yak. The expression of CGI-58 mRNA in the anagen stage was the highest, followed by the catagen stage, and the expression in the telogen stage was the lowest. The expression of KDF1 mRNA in the telogen stage was the highest, followed by the catagen stage, and the expression in the anagen stage was the lowest. MEANING:In this study, we examined and fully described the histology of normal skin in Yak and measured the skin thickness of different ages and different regions in Yak. These data may be useful to better understand and appreciate the adaptability features of yak skin. Our investigation reports the expression patterns of HSPs in yak skin for the first time. The different expression pattern of HSPs during the hair cycle suggests they may play different roles in yak hair follicle biology