A novel rat model of Dravet syndrome recapitulates clinical hallmarks.

Dravet syndrome (DS) is a debilitating infantile epileptic encephalopathy characterized by seizures induced by high body temperature (hyperthermia), sudden unexpected death in epilepsy (SUDEP), cognitive impairment, and behavioral disturbances. The most common cause of DS is haploinsufficiency of the SCN1A gene, which encodes the voltage-gated sodium channel Nav1.1. In current mouse models of DS, the epileptic phenotype is strictly dependent on the genetic background and most mouse models exhibit drastically higher SUDEP rates than patients. Therefore, we sought to develop an alternative animal model for DS. Here, we report the generation and characterization of a Scn1a halploinsufficiency rat model of DS by disrupting the Scn1a allele. Scn1a+/- rats show reduced Scn1a expression in the cerebral cortex, hippocampus and thalamus. Homozygous null rats die prematurely. Heterozygous animals are highly susceptible to heat-induced seizures, the clinical hallmark of DS, but are otherwise normal in survival, growth, and behavior without seizure induction. Hyperthermia-induced seizures activate distinct sets of neurons in the hippocampus and hypothalamus in Scn1a+/- rats. Electroencephalogram (EEG) recordings in Scn1a+/- rats reveal characteristic ictal EEG with high amplitude bursts with significantly increased delta and theta power. After the initial hyperthermia-induced seizures, non-convulsive, and convulsive seizures occur spontaneously in Scn1a+/- rats. In conclusion, we generate a Scn1a haploinsufficiency rat model with phenotypes closely resembling DS, providing a unique platform for establishing therapies for DS.

Theoretical Study for Adsorption-Diffusion on H-MOR and Pyridine Pre-adsorbed H-MOR of Dimethyl Ether Carbonylation.

For dimethyl ether (DME) carbonylation, pyridine pre-adsorbed hydrogen mordenite (H-MOR) is beneficial to prolonging the catalyst life. The adsorption and diffusion behaviors on periodic models H-AlMOR and H-AlMOR-Py were simulated. The simulation was based on Monte Carlo and molecular dynamics. The following conclusions were drawn from the simulation results. The adsorption stability of CO in 8-MR is increased, and the adsorption density of CO in 8-MR is more concentrated on H-AlMOR-Py. 8-MR is the main active site for DME carbonylation, so the introduction of pyridine would be beneficial for the main reaction. The adsorption distributions of methyl acetate (MA) (in 12-MR) and H2O on H-AlMOR-Py are significantly decreased. It means the product MA and the byproduct H2O are more easily desorbed on H-AlMOR-Py. For the mixed feed of DME carbonylation, the feed ratio (PCO/PDME) must reach 50:1 on H-AlMOR so that the reaction molar ratio can reach the theoretical value (NCO/NDME ≈ 1:1), while the feed ratio on H-AlMOR-Py is only up to 10:1. Thus, the feed ratio can be adjusted, and raw materials can reduce consumption. In conclusion, H-AlMOR-Py can improve the adsorption equilibrium of reactants CO and DME and increase the concentration of CO in 8-MR.

Synthesis of methanol over highly dispersed Cu-Fe based catalysts derived from layered double hydroxides.

In this paper, catalysts with different aluminum contents were prepared by a co-precipitation method using LDHs (layered double hydroxides) as the precursors through the adjustment of Cu2+ : Fe2+, and the catalysts were named LDO catalysts. The effect of aluminum on CO2 hydrogenation to methanol was investigated by evaluating the characterization. With the addition of Al, Ar physisorption results showed an increase in BET-specific surface area, TEM demonstrated a decrease in catalyst particle diameter, XRD showed that Cu and Fe existed in the catalyst mainly in the form of CuFe2O4 and CuO, XPS demonstrated a decrease in electron cloud density and an increase in base sites and oxygen vacancies, and CO2-TPD and H2-TPD results indicated that Al promoted the dissociation and adsorption of CO2 and H2. When the reaction temperature was 230 °C, the pressure was 4 MPa, H2/CO2 = 2.5 and the space velocity was 2000 ml (h gcat)-1, the best conversion (14.87%) and the highest methanol selectivity (39.53%) of the catalyst were obtained at 30% aluminum content.

In situ areal mass measurement of laser shock-loaded aluminum using point-projection x-ray backlighting.

X-ray backlighting is been widely used today in dynamic phenomena observation. By applying proper synchronizing techniques, the in-situ data of the intensity distribution of the fragments in laser-driven shock-loaded aluminum were obtained for a particular moment using x-ray backlighting imaging. The image resolution was better than 40 µm in this context by introducing a pinhole. In order to obtain the areal mass of the fragments, a set of reference Al step wedges with certain thicknesses was employed. Furthermore, a novel, to the best of our knowledge, calibration method is introduced to calibrate the x-ray intensity distribution. It was effective to decrease the non-uniformity influence of the x-ray intensity with this calibration method by simulating a light field. After calibration, the standard deviation of 30 regions of interest reduced to 4.17%. In consequence, the areal mass distribution of the fragments is well quantified. It should be noted that the uncertainty in the areal mass conversion mainly comes from the non-uniformity of the x-ray intensity distribution with about 5% and the measurement uncertainty of the step thicknesses with less than 10%.

Direct Conversion of Syngas to Light Olefins over a ZnCrO x + H-SSZ-13 Bifunctional Catalyst.

In recent years, bifunctional catalysts for the syngas-to-olefins (STO) reaction via the oxide-zeolite (OX-ZEO) strategy has been intensively investigated. However, the bifunctional catalyst containing H-SSZ-13 with a 100% H+-exchanging degree for the STO reaction has not been developed because of the high selectivity to paraffin. Here, we report a ZnCrO x + H-SSZ-13 bifunctional catalyst, which contains the submicron H-SSZ-13 with adequate acidic strength. Light olefins in hydrocarbon reached 70.8% at a CO conversion of 20.9% over the ZnCrO x + H-SSZ-13(23S) bifunctional catalyst at 653 K, 1.0 MPa, and GHSV = 6000 mL·g-1·h-1 after 800 min of STO reaction. The effect of CO and H2 on the C-C coupling was discussed by carrying out the methanol-to-olefins (MTO) reaction under a similar atmosphere as that of the STO reaction. H2 and CO should play a more dominant role than the conventional hydrogen transfer reaction on the undesired high selectivity of paraffins. These findings provide new insight into the design of the bifunctional catalyst for the STO process via the OX-ZEO strategy.

Direct Conversion of Syngas to Light Olefins through Fischer-Tropsch Synthesis over Fe-Zr Catalysts Modified with Sodium.

Fe-Zr-Na catalysts synthesized by coprecipitation and impregnation methods were implemented to investigate the promoting effects of Na and Zr on the iron-based catalyst for high-temperature Fischer-Tropsch synthesis (HTFT). The catalysts were characterized by Ar adsorption-desorption, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, CO temperature-programmed desorption, H2 temperature-programmed desorption, X-ray photoelectron spectroscopy, and Mössbauer spectroscopy (MES). The results indicated that Na changed the active sites on the catalyst surface for the CO and hydrogen adsorption, owing to the electron migration from Na to Fe atoms, which resulted in an enhanced CO dissociative adsorption and a decrease in hydrogen adsorption on the metallic Fe surface. The decreased H/C ratio on the catalyst surface accounted for the increased chain propagation and weakened hydrogenation of light olefins. Besides, Na could also facilitate the carbonization of catalysts and protect the iron carbide against oxidation, which provides more active sites for HTFT reaction and is beneficial to the C-C coupling. Zr could decrease the hematite crystallite size and stabilize the active phase to improve the HTFT activity. At an optimal Na loading of 1.0 wt %, the Fe-Zr-1.0Na catalyst exhibited the highest light olefin selectivity of 35.8% in the hydrocarbon distribution at a CO conversion of 95.2%.

Utilization of SAPO-18 or SAPO-35 in the bifunctional catalyst for the direct conversion of syngas to light olefins.

SAPO-18 and SAPO-35 were synthesized and utilized as the zeotype in the bifunctional catalyst for the STO process, respectively. SEM and Ar physisorption proved that SAPO-18 displayed abundant outer cages, and facilitated the diffusion of the reactant and products. NH3-TPD revealed the adequate acid strength of SAPO-18, thus ZnCrO x + SAPO-18 bifunctional catalyst showed high selectivity to light olefins during the whole stage of the STO process. 19.9% CO conversion and 68.6% light olefins selectivity (free of CO2) was achieved over ZnCrO x + SAPO-18(0.048) at 653 K, 1.0 MPa, GHSV = 6000 mL g-1 h-1. The catalytic performance was stable after 6000 minutes of reaction because of the good diffusibility of SAPO-18. GC-MS and TG demonstrated that the ZnCrO x + SAPO-35 bifunctional catalyst deactivated very quickly because of the severe formation of the heavy coke deposits, which should be attributed to the acidic properties of SAPO-35 and the poor diffusibility originating from its 2-dimensional channel system. Although the ZnCrO x + SAPO-35 bifunctional catalyst exhibited high CO conversion and light olefins selectivity at the early stage of the STO process as well, its catalytic performance was unsustainable.

Combustion Products of Calcium Carbide Reused by Cu-Based Catalysts for Acetylene Carbonylation.

Sustainable development is a worldwide concern. This work mainly focuses on the reuse of the combustion products of calcium carbide and the influence of different kinds of copper on the acetylene carbonylation reaction. A series of catalysts were prepared by heating the precursors under various atmospheres (air, hydrogen, and nitrogen). The X-ray diffraction and the X-ray photoelectron spectroscopy have been analyzed regarding copper species composition and content in catalysts. The result of the Cu+-promoted reaction was in good agreement with the conducted density functional theory analysis, and we speculate that Cu+ promotes the transfer of electrons in the reaction. Transmission electron microscopy and elemental mapping evaluation confirmed the difference in Cu dispersion. Characterization of catalysts using temperature programmed desorption and pyridine Fourier-transform infrared revealed differences in their acidity. Acidity was found to be favorable for acetylene carbonylation. Selectivity and yield of the CuAlZn-LDO(N) catalyst at 225 °C were 73 and 70%, respectively, and the catalyst showed good stability over two consecutive cycles of reuse.

Synthesis of Submicron SSZ-13 with Tunable Acidity by the Seed-Assisted Method and Its Performance and Coking Behavior in the MTO Reaction.

Submicron SSZ-13 with different acidities was synthesized successfully with the assistance of nanosized SSZ-13 seeds. The methanol-to-olefins (MTO) properties of submicron SSZ-13 were evaluated. The lifetime of submicron SSZ-13 was enhanced because of the crystal size reduction. The selectivity of light olefins was improved evidently at the early stage of the MTO reaction as the acidity density decreased. TG, GC-MS, and in situ UV/vis spectra were utilized to investigate coking behavior during the MTO reaction. It was found that the acidity density influences the nature and rate of coke formation. The majority of the hydrocarbon pool species over SSZ-13 with a low acidity density (125.2 µmol/g) were methylated benzene carbocations, while that over SSZ-13 with a high acidity density (330.2 µmol/g) were methylated naphthalene carbocations. The low acidity density of SSZ-13 can suppress the hydrogen transfer reaction and polyaromatic generation.

Study of the Fischer-Tropsch synthesis on nano-precipitated iron-based catalysts with different particle sizes.

Nano iron-based catalysts with different particle sizes were prepared by a co-precipitated method and characterized by XRD, N2 adsorption, SEM, Mössbauer spectroscopy, XPS, H2-TPR, CO-TPD, H2-TPD and TGA. The CO-TPD results revealed that large particle sizes of catalysts were not conducive to the adsorption of CO, and exhibited low activity of FTS. The decrease of catalyst particle size enhanced the interaction between Fe and Mn, and promoted the CO chemical adsorption and the formation of Fe5C2, but the hydrogenation reaction was inhibited as confirmed by H2-TPD. When the particle size continued to decrease, Mössbauer spectroscopy showed that MnFe2O4 appeared in the catalyst phase, which hindered the reduction of catalysts and the adsorption of feed gas. Overall, the sample FeMnSm-600 showed the highest C[double bond, length as m-dash] 2-4 selectivity of 33% at the highest CO conversion of 79% during the reaction conditions of 300 °C, 1.0 MPa, 12 000 mL (g h)-1, and H2/CO = 2.

Effects of Sm on Fe-Mn catalysts for Fischer-Tropsch synthesis.

Sm-promoted FeMn catalysts were prepared by the co-precipitation method and characterized by N2 adsorption, XRD, CO-TPD, H2-TPD, CO2-TPD, H2-TPR, XPS and MES. It was found that compared with the un-promoted catalyst, when Sm was added at a proper content, the catalyst showed a larger BET surface area and promoted the formation of iron particles with a smaller size. The presence of Sm could increase the surface charge density of iron, which enhanced the Fe-C bond and promoted the stability and amount of CO dissociated adsorption, as confirmed by XPS and CO-TPD. Furthermore, according to MES, Sm could promote the formation of Fe5C2, which was the active phase of FTS. In addition, Sm could also enhance the basicity of the catalysts and suppress the H2 adsorption capacity, which inhibited the hydrogenation reaction and the conversion of olefins to paraffins, as verified by the results of CO2-TPD and H2-TPD. According to the FTS performance results, compared with the observations for the un-promoted catalysts, when the molar ratio of Sm to Fe was 1%, the CO conversion increased from 63.4% to 70.4%, the sum of light olefins in the product distribution increased from 26.6% to 32.6, and the ratio of olefins to paraffins increased to 4.18 from 4.09.

Effects of Polymer Length and Salt Concentration on the Transport of ssDNA in Nanofluidic Channels.

Electrokinetic phenomena in micro/nanofluidic channels have attracted considerable attention because precise control of molecular transport in liquids is required to optically and electrically capture the behavior of single molecules. However, the detailed mechanisms of polymer transport influenced by electroosmotic flows and electric fields in micro/nanofluidic channels have not yet been elucidated. In this study, a Langevin dynamics simulation was used to investigate the electrokinetic transport of single-stranded DNA (ssDNA) in a cylindrical nanochannel, employing a coarse-grained bead-spring model that quantitatively reproduced the radius of gyration, diffusion coefficient, and electrophoretic mobility of the polymer. Using this practical scale model, transport regimes of ssDNA with respect to the ζ-potential of the channel wall, the ion concentration, and the polymer length were successfully characterized. It was found that the relationship between the radius of gyration of ssDNA and the channel radius is critical to the formation of deformation regimes in a narrow channel. We conclude that a combination of electroosmotic flow velocity gradients and electric fields due to electrically polarized channel surfaces affects the alignment of molecular conformations, such that the ssDNA is stretched/compressed at negative/positive ζ-potentials in comparatively low-concentration solutions. Furthermore, this work suggests the possibility of controlling the center-of-mass position by tuning the salt concentration. These results should be applicable to the design of molecular manipulation techniques based on liquid flows in micro/nanofluidic devices.

Preoperative diffusion-weighted imaging value of rectal cancer: preoperative T staging and correlations with histological T stage.

PURPOSE: To assess the ability of diffusion-weighted imaging (DWI) for evaluating T stage and correlation with histological T stage of rectal cancer. METHOD: The diagnostic accuracy, sensitivity, and specificity of T2WI and DWI combined with T2WI for T stage were evaluated. Mean tumor apparent diffusion coefficient (ADC) was compared with histological T stage. RESULT: There were no significant differences in the diagnostic accuracy, sensitivity, and specificity no matter what kind of T stage was concerned. The difference between ADC values and histological T stage were significantly different. CONCLUSION: DWI was useful for evaluating T stage of rectal cancer. The ADC may predict the histological grade.

[Associations of apparent diffusion coefficient value from MR diffusion-weighted imaging with Ki-67 expression and differentiation grade in gastric cancer].

OBJECTIVE: To examine the associations of apparent diffusion coefficient (ADC) value from MR diffusion-weighted imaging (DWI) with Ki-67 expression and differentiation grade in gastric cancer. METHODS: Images and pathologic data of 68 gastric cancer patients between September 2013 and February 2015 in Affiliated Changshu Hospital of Soochow University were analyzed retrospectively. The expression of Ki-67 antigen in cancer tissue sample was determined by immunohistochemistry. Ki-67 labeling index(LI) was calculated to divide the cases into low Ki-67 group(Ki-67 LI <50%) and high Ki-67 group (Ki-67 LI ≥ 50%). Associations of ADC value with differentiation grade and Ki-67 LI were examined. RESULTS: Mean ADC value of low Ki-67 LI group was significantly higher than that of high Ki-67 LI group [(0.977 ± 0.100) × 10(-3) mm(2)/s vs. (0.859 ± 0.064) × 10(-3) mm(2)/s, P=0.000]. The ADC value was negatively correlated with Ki-67 LI (r=-0.685, P=0.000). Mean ADC value of well differentiated adenocarcinoma, moderately differentiated adenocarcinoma, poorly differentiated adenocarcinoma, and signet-ring cell carcinoma was (1.124 ± 0.080) × 10(-3) mm(2)/s, (0.950 ± 0.064) × 10(-3) mm(2)/s, (0.899 ± 0.091) × 10(-3) mm(2)/s, and (0.894 ± 0.081) × 10(-3) mm(2)/s respectively. Difference of ADC value among differentiation grades was significantly different (F=11.405, P=0.000). Difference of ADC value between well differentiated adenocarcinoma and non-well differentiated adenocarcinoma was significantly different(P=0.000). CONCLUSION: ADC value is associated with differentiation grade and Ki-67 LI of gastric cancer, which may be used as a noninvasive predictor for evaluating the proliferation and differentiation grade of gastric cancer.

[Value of diffusion-weighted MRI in the diagnosis of T staging for rectal cancer].

OBJECTIVE: To investigate the value of diffusion-weighted imaging (DWI) in the diagnosis of T staging for rectal cancer. METHODS: Clinicopathologic data and MR images of 46 patients with rectal cancer in our hospital from July 2013 to September 2014 were retrospectively analyzed. The diagnostic sensitivity, specificity and accuracy of T2WI were compared with those of T2WI plus DWI in T staging for rectal cancer. The relationship of mean apparent diffusion coefficient (ADC) value with different T stages of rectal cancer was analyzed. RESULTS: There were no significant differences in the diagnostic sensitivity, specificity and accuracy between T2WI and T2WI plus DWI (all P>0.05). The mean ADC value of DWI performed in pathologic T2, T3a, T3b, T3c and T4 stage was (1.110 ± 0.117) × 10⁻³ mm²/s, (1.035 ± 0.121) × 10⁻³ mm²/s, (0.948 ± 0.109) × 10⁻³ mm²/s, (0.932 ± 0.122) × 10⁻³ mm²/s and (0.843 ± 0.050) × 10⁻³ mm²/s, respectively (F=6.972, P=0.000). CONCLUSION: DWI can serve as a complement for T2WI in the diagnosis of T stage patients with rectal cancer, and its ADC value presents a downward trend with the advance of T stage.

Theoretical study of the transpore velocity control of single-stranded DNA.

The electrokinetic transport dynamics of deoxyribonucleic acid (DNA) molecules have recently attracted significant attention in various fields of research. Our group is interested in the detailed examination of the behavior of DNA when confined in micro/nanofluidic channels. In the present study, the translocation mechanism of a DNA-like polymer chain in a nanofluidic channel was investigated using Langevin dynamics simulations. A coarse-grained bead-spring model was developed to simulate the dynamics of a long polymer chain passing through a rectangular cross-section nanopore embedded in a nanochannel, under the influence of a nonuniform electric field. Varying the cross-sectional area of the nanopore was found to allow optimization of the translocation process through modification of the electric field in the flow channel, since a drastic drop in the electric potential at the nanopore was induced by changing the cross-section. Furthermore, the configuration of the polymer chain in the nanopore was observed to determine its translocation velocity. The competition between the strength of the electric field and confinement in the small pore produces various transport mechanisms and the results of this study thus represent a means of optimizing the design of nanofluidic devices for single molecule detection.

Aggressive osteoblastoma of the temporal bone: a case report and review of the literature.

Osteoblastoma can take place in any part of the skeleton. Its occurrence in the calvarium is extremely rare. The aggressive form of osteoblastoma is a rare variant. To our knowledge, this is the second case of aggressive osteoblastoma arising in the temporal bone. We report an 18-year-old patient with aggressive osteoblastoma involving the left temporal bone. Computed tomography of temporal bone showed an osteolytic lesion with granular mineralization and mottled ossified density. Permanent histopathologic sections and immunohistochemical stains revealed an aggressive osteoblastoma.

A new nonlinear reconstruction method based on total variation regularization of neutron penumbral imaging.

Neutron penumbral imaging is a significant diagnostic technique in laser-driven inertial confinement fusion experiment. It is very important to develop a new reconstruction method to improve the resolution of neutron penumbral imaging. A new nonlinear reconstruction method based on total variation (TV) regularization is proposed in this paper. A TV-norm is used as regularized term to construct a smoothing functional for penumbral image reconstruction in the new method, in this way, the problem of penumbral image reconstruction is transformed to the problem of a functional minimization. In addition, a fixed point iteration scheme is introduced to solve the problem of functional minimization. The numerical experimental results show that, compared to linear reconstruction method based on Wiener filter, the TV regularized nonlinear reconstruction method is beneficial to improve the quality of reconstructed image with better performance of noise smoothing and edge preserving. Meanwhile, it can also obtain the spatial resolution with 5 µm which is higher than the Wiener method.

Evidence of chemical bonding to hydroxyapatite by phosphoric acid esters.

Phosphoric acid esters (PAEs) have been used as a self-etching primer for composite-to-enamel bonding in adhesive dentistry. However, the chemical mechanism of their interactions with hydroxyapatite (HA) is not clear. In the present study, HA particles were mixed with Resulcin AquaPrime (Merz Co.) priming agent that contains a mixture of PAEs, and dried. The primer, HA and the mixture of both were analyzed by FTIR. Primed and untreated HA discs were analyzed with attenuated total reflectance (ATR). After AquaPrime+D(2)O (1:1) was mixed with HA or Ca(OD)(2) for 48 h, the primer and both mixtures were analyzed with (31)P NMR in D(2)O. The solid and the liquid separated from both mixtures were analyzed with (31)P NMR in CDCl(3). The primer's characteristic bands (nu(CO), nu(CC)) were found on the primer-subtracted mixture's spectrum and the primed HA disc. (31)P NMR data indicated that the reactions of PAEs with HA produced PAEs-HA complexes, and were not a simple acid-base reaction like those with Ca(OD)(2), either in liquid or in solid. It is concluded that phosphoric acid esters can decalcify and adhere to hydroxyapatite simultaneously.

Evidence of chemisorption of maleic acid to enamel and hydroxyapatite.

Maleic acid has been used as an etchant or non-rinse conditioner in adhesive dentistry. However, the inherent mechanisms of the interaction of maleic acid with hydroxyapatite/enamel have never been fully elucidated. The purpose of this study was to provide evidence for the chemisorption of maleic acid onto hydroxyapatite/enamel, and to identify the reaction products obtained following the interaction of maleic acid with hydroxyapatite. Hydroxyapatite particles were dissolved in a 15% (w/v) aqueous solution of maleic acid (pH = 0.98). Half of the solution was dried to obtain a desiccated mixture. This mixture, hydroxyapatite, maleic acid and self-prepared calcium maleate were analysed by X-ray diffraction (XRD). Acetone was added to the other half of the solution to obtain a precipitate. This precipitate, hydroxyapatite, maleic acid, unetched enamel and maleic acid-etched enamel were analysed by X-ray photoelectron spectroscopy (XPS). The precipitate was also analysed by (1)H NMR. A new binding energy, indicating carboxylate groups, was detected by XPS on the precipitate and maleic acid-etched enamel surface. XRD data indicated the formation of calcium maleate and calcium hydrogen phosphate after the reaction. NMR data revealed that one carboxylic group of maleic acid reacted with hydroxyapatite. Hence, maleic acid can chemisorb to hydroxyapatite and enamel via ionic interactions.