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Abstract Background The preparation of the middle mesial (MM) canal of mandibular molars represents a challenge because it is often curved, narrow, and close to the root concave. The purpose of this study was to evaluate the ex vivo shaping ability of 3 nickel-titanium (NiTi) rotary systems in the MM canal using 3D printed resin tooth replicas. Methods A permanent mandibular first molar with a MM canal was acquired from a pool of extracted teeth and reproduced by a 3D printer. The resin tooth replicas (n = 18) were equally assigned to 3 groups for the evaluation of the shaping abilities of 3 NiTi rotary systems (OneShape [OS], Twisted Files [TF], and ProTaper Gold [PTG]) according to the manufacturer’s recommendations. The tooth replicas were scanned by micro-computed tomography (micro-CT) twice before and after instrumentation of the mesiobuccal (MB), mesiolingual (ML), and MM root canals. After 3D reconstruction, the canal straightening, change of root canal volume and surface area, the mesial and distal canal wall thickness and canal transportation at the levels of 1, 2, and 3 mm below furcation were assessed. One-way variance analysis and Turkey’s post hoc test were used for comparisons of the means among different groups, and paired-t test was used to compare the mesial and distal sides of the mesial roots. Results As compared with OS and TF, the use of PTG in preparation of MM canals resulted in significantly more straightening of canal curvature (p 0.05) after the preparation of the MB and ML canals. However, in the MM canal, more pronounced transportation was detected in the PTG group at 2 mm below furcation, and in the TF group at 3 mm below furcation as compared with the other 2 systems (both p

Abstract Background In recent years, cone-beam computed tomography (CBCT) has been widely used to evaluate patients’ root canal anatomy due to its high resolution and noninvasive nature. As voxel size is one of the most important parameters affecting CBCT image quality, the current study evaluated the diagnostic potential of CBCT with 4 different voxel sizes in the detection of double root canal systems and accessory canals (ACs) in permanent mandibular incisors. Methods A total of 106 extracted mandibular permanent incisors were collected from the dental clinics, and then were scanned by using micro-CT with a voxel size of 9 μm. The teeth were then fixed in the tooth sockets of human dry mandibles and scanned by using a CBCT device with 4 different voxel sizes (300, 200, 250, and 125 μm). Four observers detected in blind the root canal morphology of the teeth according to the CBCT images, and the presence or absence of a double root canal system, and the presence or absence of ACs, were scored according to a 5-point scale, respectively. Receiver operating characteristic (ROC) analysis was performed, and DeLong test was used to compare the area under the curve (AUC) values and the micro-CT data was taken as a gold standard. Results Among 106 sample teeth, 25 specimens with a double root canal system were identified by the micro-CT. ROC curve analysis of the data obtained by the four observers showed that in the detection of double root canal systems, the AUC values ranged from 0.765 to 0.889 for 300 μm voxel size, from 0.877 to 0.926 for 250 μm voxel size, from 0.893 to 0.967 for 200 μm voxel size, and from 0.914 to 0.967 for 125 μm voxel size (all p

In this paper, a series of porous hierarchical Mg/Al layered double hydroxides (named as LDH, TTAC-MgAl-LDH, CTAC-MgAl-LDH, and OTAC-MgAl-LDH) was synthesized by a simple green hydrothermal method using wormlike micelles formed by salicylic acid and surfactants with different carbon chain lengths (0, 14, 16, and 18) as soft templates. BET, XRD, FTIR, TG, and SEM characterizations were carried out in order to investigate the structure and properties of the prepared materials. The results showed that the porous hierarchical CTAC-MgAl-LDH had a large specific surface area and multiple pore size distributions which could effectively increase the reaction area and allow better absorption capability. Benefiting from the unique architecture, CTAC-MgAl-LDH exhibited a large adsorption capacity for sulfonated lignite (231.70 mg/g) at 25 °C and a pH of 7, which outperformed the traditional LDH (86.05 mg/g), TTAC-MgAl-LDH (108.15 mg/g), and OTAC-MgAl-LDH (110.51 mg/g). The adsorption process of sulfonated lignite followed the pseudo-second-order kinetics model and conformed the Freundlich isotherm model with spontaneous heat absorption, which revealed that electrostatic adsorption and ion exchange were the main mechanisms of action for the adsorption. In addition, CTAC-MgAl-LDH showed a satisfactory long-time stability and its adsorption capacities were still as high as 198.64 mg/g after two adsorption cycles.

Gegen Qinlian Decoction (GQD) is a Chinese herbal medicine that has been reported to significantly decrease blood glucose levels, which is suggested to be related to interactions with the gut microbiota. However, the protective effect of GQD on intestinal barrier function with regard to its influence on the gut microbiota has not been explored to date. In this study, we investigated the role of the gut microbiota in mediating the hypoglycemic mechanism of GQD in type 2 diabetes mellitus (T2DM) rats induced by a single intraperitoneal injection of streptozotocin after 4 weeks of high-fat diet feeding. The T2DM rats were randomly allocated to receive GQD, metformin (Met), or saline for 12 consecutive weeks, and changes in metabolic parameters, intestinal barrier function, and inflammation were investigated. Gut microbiota was analyzed using 16S rRNA gene sequencing from fecal samples, and statistical analyses were performed to correlate microbiota composition with phenotypes of the T2DM rats. GQD administration decreased the levels of blood glucose and inflammatory cytokines, and increased the levels of tight junction proteins. Besides, GQD had a protective effect on islet function, restoring intestinal permeability, and inhibiting inflammation, as evidenced by increases in the levels of serum C-peptide, occludin, and claudin-1 in the colon, and also improved the expression of serum inflammatory factors. In addition, GQD regulated the structure of the gut microbiota by increasing the proportions of short-chain fatty acids-producing and anti-inflammatory bacteria, and decreasing the proportions of conditioned pathogenic bacteria associated with the diabetic phenotype. Overall, these findings suggest that GQD could ameliorate hyperglycemia and protect islet function by regulating the structure of the gut microbiota, thereby restoring intestinal permeability and inhibiting inflammation in T2DM rats. Our study thus suggests that the hypoglycemic mechanism of GQD is mediated by its modulation of the gut microbiota.

A high-sensitive and transverse-stress compensated methane sensor based on a photonic crystal fiber long-period grating (PCF-LPG) is proposed. The outermost layer of the PCF consists of six large sideholes, five of which are coated with methane-sensitive compound film to achieve methane measurement. Such side-hole structure is helpful for gas sensitive reaction, but not conducive to avoiding external stress interference. Therefore, the last large hole is plated with silver layer to eliminate the cross-sensitivity effect through adding a Surface Plasmon Resonance (SPR) sensing channel with the consideration of photo-elastic effect and material deformation. Results show that the methane gas sensitivity can reach up to 6.39nm/% with the transverse-stress compensation. The sensor is very simple and effective, which provides a new method of gas measurement combined with different actual conditions.

A temperature-controlled dual-core photonic crystal fiber splitter having multiple coupling characteristics is designed through infiltrating a mixture of toluene and chloroform into the twin-core holes. Multiple splitting functions are integrated in the same PCF structure with a fixed length. The incident light within the range of 1.30–1.70 μm can be divided into two polarized components in orthogonal directions. The maximum bandwidth and extinction ratio can reach 255 nm and −68 dB when the external temperature varies from 10 °C to 27 °C. Especially, the polarized light waves in one core can shift from previous y-polarization to x-polarization at certain higher temperatures or vice versa. Meanwhile, the proposed splitter can realize the wavelength splitting of 1.30 μm/1.49 μm, 1.30 μm/1.55 μm, 0.85 μm/1.55 μm and 1.49 μm/1.63 μm through manipulating the operating temperature. The PCF-based splitter has simpler structure and better performance, and has great potential applications in the field of integrated optoelectronics.

In this study, hierarchical MgAl-LDH (layered double hydroxide) nanoparticles with a flower-like morphology were prepared under a hydrothermal condition by employing worm-like micelles formed by cetyltrimethylammonium bromide (CTAB) and salicylic acid (SA) as templates. The morphology and structure of the materials were characterized by Brunauer–Emmett–Teller (BET), SEM, and XRD analyses. The performance for the adsorption of sulfonated lignite (SL) was also investigated in detail. FTIR was used to detect the presence of active functional groups and determine whether they play important roles in adsorption. The results showed that the hierarchical MgAl-LDH nanoparticles with a specific surface area of 126.31 m2/g possessed a flower-like morphology and meso–macroporous structures. The adsorption capacity was high—its value was 1014.20 mg/g at a temperature of 298 K and an initial pH = 7, which was higher than traditional MgAl-LDH (86 mg/g). The adsorption process of sulfonated lignite followed the pseudo-second-order kinetics model and conformed to Freundlich isotherm model with a spontaneous exothermic nature. In addition, the hierarchical MgAl-LDH could be regenerated and used, and the adsorption was high after three adsorption cycles. The main adsorption mechanisms were electrostatic attraction and ion exchange between the hierarchical MgAl-LDH and sulfonated lignite.

This paper proposes a methane sensor based on localized surface plasmon resonance (LSPR) of a hexagonal periodic gold nanoring array. The effects of structural parameters on the extinction spectrum and refractive index (RI) sensitivity are analyzed to obtain optimal parameters. In particular, the RI sensitivity can reach 550.08 nm/RIU through improvement of the sensor structure, which is an increase of 17.4% over the original value. After coating a methane-sensitive membrane on the inner and outer surfaces of the gold rings, the methane concentration can be accurately measured with a gas sensitivity of −1.02 nm/%. The proposed method is also applicable to quantitative analyses of components concentration and qualitative analyses of gas composition.

Sulfonated lignite (SL) is extensively utilized in petroleum exploration; however, its effective removal from wastewater poses a significant challenge. China's environmental protection department has classified it as a regulated oilfield chemical. In this study, hierarchically porous layered double hydroxide nanoparticles was prepared based on the soft template of cetyltrimethylammonium chloride and salicylic acid under hydrothermal condition. The effects of surfactant concentrations on the physical properties of the obtained adsorbents have been investigated by using X-ray powder diffraction, scanning electron microscopy, Brunauer-Emmett-Teller, and Fourier-transform infrared spectroscopy characterizations. It was found that three-dimensionally hydrotalcite nanosheets attached uniformly on the surface of soft template, generating higher crystallization and large specific area. Furthermore, the adsorption capacity of the material to SL was investigated to evaluate its application for the treatment of oilfield wastewater. The maximum adsorption capacity was equal to 854.70 mg/g at 298 K and pH of 7, which is significantly higher than the adsorption capacity of ordinary hydrotalcite (56.3 mg/g). The adsorption reaction followed the pseudo-secondorder kinetics as well as the Freundlich isotherm model. Moreover, thermodynamic investigations showed that adsorption exhibits exothermic characteristics. After three adsorption-desorption cycles, hierarchically porous hydrotalcite nanoparticles still exhibit a high adsorption capacity of up to 187.7 mg/g. Anion exchange and electrostatic attraction were considered as the main adsorption mechanisms. [ABSTRACT FROM AUTHOR]