[en] Objective: To investigate the in vitro CT imaging parameters of gold nanorods as novel CT contrast agents. Methods: Gold nanorods were prepared with a gold seed and a growth solution. PEG-modified gold nanorods and non-ionic iodine contrast agent were configured into eight concentrations (0, 0.1, 0.2, 0.4, 0.6, 0.8, 1.0, 2.0 mg/mL). The different concentrations of the gold nanorod solutions in air and water bath were subjected to in vitro CT scanning imaging at different tube voltages (80-140 kV) and milliamp seconds (50-400 mAs). The development effect was observed, and the CT value was measured. Results: (1) At different concentrations of the gold nanorod solutions, the CT value scanned in water is the closest to the true value, whereas the CT value in air is low. (2) The lower the tube voltage is, the higher the CT value of the gold nanorod solution is. At a solution concentration of 2.0 mg/mL, the difference in the signal-to-noise ratio at different tube voltages is evident. (3) The image quality is positively correlated with mAs, but the image quality is not significantly changed at ≥ 300 mAs. (3) At 80 kV and 300 mAs, the CT values of the gold nanorods and the iodine contrast agent increase as the concentration increases and show a highly positive correlation (r = 0.990, 0.994, both P < 0.05). The difference in CT values between the two agents increases, and the contrast of the gold nanorods is higher than that of the iodine contrast agents. Conclusion: Gold nanorods exhibit superior imaging characteristics to those of existing CT contrast agents. When gold nanorods are scanned with iCT at 80 kV and 300 mAs and under water bath conditions, an excellent image quality can be achieved. (authors)

[en] The laser-interference-induced backward transfer (LIIBT) that occurred during the nanostripe structuring of materials, performed by two-beam laser interference at the ITO glass/silicon wafer system under a normal atmospheric environment. The results showed that the nanostripe structures with nanoparticles (NPs) can be obtained at the laser fluence of 65–95 mJ·cm⁻² for the laser duration of 100 and 200 pulses, respectively. The EDX analysis revealed that the silicon element was transferred on the surface of the nanostripe structures. In addition, Raman spectra with the peaks at ~520 cm⁻¹ verified that the crystalline silicon was deposited on the nanostripe structures during the LIIBT process. Furthermore, the photoluminescence (PL) spectrum with the peak at ~395 nm belongs to the In₂O₃ nanostructure at the laser fluence of 45 mJ·cm⁻² for 200 pulses. The peak at ~405 nm corresponds to the silicon nanostructures and it is covered by SiO at the laser fluence of 75 mJ·cm⁻² for 200 pulses. The LIIBT shown here would greatly reduce the complexity in the fabrication of the nanostripe structures and give an impetus to the laser-induced backward transfer.

[en] Molecular dynamics simulation is used to investigate the relationship between Voronoi entropy and viscosity for rapid solidification processing of Zr_3_6Cu_6_4 binary alloy melt. The simulation results at different temperatures, cooling rates, and pressures, show that Voronoi entropy is able to accurately describe the relationship of the transition between the cluster structure and the viscosity of Zr_3_6Cu_6_4 binary alloy melt through Voronoi polyhedron analysis. That is, the higher the degree of order of the microstructure, the lower the Voronoi entropy is and the higher the viscosity is. The simulation provides an important reference for studying metallic glass with high glass-forming ability. (paper)

[en] Zr—Ti binary alloys are prepared using a nonconsumable tungsten electrode under Ti-gettered inert atmosphere (argon). Microstructures are observed mainly as α phase using x-ray diffraction. A tensile test is performed to investigate the tensile strength of a series of Zr—Ti binary alloys at room temperature. The findings indicate that increasing Ti concentration results in an initial increase (≪50at% of Ti) and then a decrease in tensile strength. The Zr55Ti45 (at%) component exhibits the maximum tensile strength of 1216.68MPa, which is much higher than that of pure Ti (increased by approximately 200%) or pure Zr (increased by approximately 100%). The potential mechanisms for the remarkable tensile strength are solid solution strengthening and grain refinement

[en] A molecular dynamics simulation is performed to investigate the relationship between the local five-fold symmetry and the diffusion behavior involved in the rapid solidification of a Zr_6_4Cu_3_6 alloy melt. The Voronoi polyhedron analysis indicates that the icosahedral clusters cannot explain the total amorphous structure, while the local fivefold symmetry shows more advantage in describing the relationship between the transition of the clusters and the diffusion behavior of Zr_6_4Cu_3_6 amorphous alloy. It is found that when the fraction of the local five-fold symmetry is less than 0.3, the diffusion coefficient increases significantly, and when the value exceeds 0.7, diffusion behavior is inhibited. The simulation provides a new viewpoint for understanding of the glass-forming mechanism. (paper)

[en] Objective: To explore the diagnostic value of DWI after secretin stimulation for the diagnosis of mild chronic pancreatitis (CP). Methods: This was a prospective study. Ninety-nine consecutive individuals including 23 healthy volunteers, 11 risk volunteers, 15 mild CP patients, 14 moderate CP patients and 36 severe CP patients underwent secretin DWI and faecal elastase 1(FE-1) testing. The subjects were grouped by Cambridge classification about endoscopic retrograde cholangiography (ERCP), CT and ultrasonography. Secretin stimulated diffusion weighted imaging(S-DWI), the ADCs, time to peak ADCs and FE-1 were performed on all subjects. The changes of pancreatic ADC values were observed before and after the injection of secretin. All ADCs and FE-1 were compared between groups with single factor analysis of variance, and the correlation between ADCs and FE-1 was determined with Pearson analysis. ROC curves were performed to identify the diagnostic efficacy of DWI related measures. Results: Eight patients with severe CP were excluded because the significant atrophy of the pancreatic parenchyma prohibited the evaluation of ADC measurement. Ninety-one individuals were divided into five groups including 23 healthy volunteers, 11 risk volunteers, 15 mild CP patients, 14 moderate CP patients and 28 severe CP patients. The mean baseline and peak ADCs were higher in the healthy volunteers than in other groups, with significant differences (P < 0.05). There was no ADC peak in severe CP patients. There were significant differences between the mean baseline ADCs and the peak ADCs in the other groups (P < 0.05). The mild and moderate CP groups showed a delayed peak. The area under curve (AUC) of the mean baseline and peak ADCs, time to peak ADCs for differentiating mild CP was 0.818, 0.912 and 0.965, respectively. Using 4.67 min as the cutoff value, time to peak ADCs were most accurate for differentiating healthy from risk patients and those with evident pancreatitis, yielding a sensitivity of 80.0% and a specificity of 100.0%. Good correlations between baseline and peak ADCs, time to peak ADCs, and FE-1 were shown(r = 0.57, 0.72 and -0.84, P < 0.01). Conclusions: Using the peak and time to peak ADCs may improve the detection of risk and mild CP. Secretin-enhanced DWI is a noninvasive, convenient and accurate method. (authors)

[en] A remarkable enhancement in room-temperature compressive deformability is realized by the minor-addition of 1.5 at.% Al in ZrTi-based bulk metallic glass. Two amorphous phases are observed by transmission electron microscopy in the Al-containing alloys and this explains the improvement of compression deformability The studies suggest that phase separation might occur in glass forming alloys with a negative enthalpy of mixing. (condensed matter: structure, mechanical and thermal properties)

[en] Portland cement is the most common type of cement in general use around the world as a basic ingredient of concrete, mortar, stucco, and non-speciality grout. Dicalcium silicate (Ca ₂ SiO ₄ ) is the primary constituent of a number of different types of cement. The β -Ca ₂SiO₄ phase is metastable at room temperature and will transform into γ -Ca ₂ SiO ₄ at 663 K. In this work, Portland cement is annealed at a temperature of 950 K under pressures in the range of 0–5.5 GPa. The high pressure experiments are carried out in an apparatus with six anvil tops. The effect of high pressure on the obtaining nano-size β-Ca ₂ SiO ₄ (C ₂ S) process is investigated by x-ray diffraction and transmission electron microscopy. Experimental results show that the grain size of the C ₂ S decreases with the increase of pressure. The volume fraction of the C ₂ S phase increases with the pressure as the pressure is below 3 GPa, and then decreases ( P > 3 GPa). The nano-effect is very important to the stabilization of β -Ca ₂SiO₄. The mechanism for the effects of the high pressure on the annealing process of the Portland cement is also discussed. (paper)

[en] The Voronoi structural evolution of silicon upon melting is investigated using a molecular dynamics simulation. At temperatures below the melting point, the solid state system is identified to have a four-fold coordination structure <4,0,0,0>. As the temperature increases, the five-fold coordination <2,3,0,0> and six-fold coordination structures <2,2,2,0> and <0,6,0,0> are observed. This is explained in terms of increasing atomic displacement due to thermal motion and the trapping of the moving atoms by others. At temperatures above the melting point, nearly all of the four-fold coordination structures grows into multiple-fold coordination ones. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

[en] The structural, elastic, electronic, and thermodynamic properties of Zr_xNb_1−xC alloys are investigated using the first principles method based on the density functional theory. The results show that the structural properties of Zr_xNb_1−xC alloys vary continuously with the increase of Zr composition. The alloy possesses both the highest shear modulus (215 GPa) and a higher bulk modulus (294 GPa), with a Zr composition of 0.21. Meanwhile, the Zr_0.21 Nb_0.79C alloy shows metallic conductivity based on the analysis of the density of states. In addition, the thermodynamic stability of the designed alloys is estimated using the calculated enthalpy of mixing. (condensed matter: electronic structure, electrical, magnetic, and optical properties)