Fresnel zone plate sculptured out of diamond by femtosecond laser for harsh environments.

With the rapid development of micro-optical applications, there is an increasing demand for micro-optical elements that can be made with minimal processing steps. Current research focuses on practical functionalities of optical performance, lightweight, miniaturization, and easy integration. As an important planar diffractive optical element, the Fresnel zone plate (FZP) provides a compact solution for focusing and imaging. However, the fabrication of FZPs with high quality out of hard and brittle materials remains challenging. Here, we report on the fabrication of diamond FZP by femtosecond laser direct writing. FZPs with the same outer diameter and different focal lengths of 250-1000 µm were made via ablation. The fabricated FZPs possess well-defined geometry and excellent focusing and imaging ability in the visible spectral range. Arrays of FZPs with different focal lengths were made for potential applications in imaging, sensing, and integrated optical systems.

Prediction Model for Liquid-Assisted Femtosecond Laser Micro Milling of Quartz without Taper.

The strong nonlinear absorption effect and "cold" processing characteristics of femtosecond lasers make them uniquely advantageous and promising for the micro- and nanoprocessing of hard and brittle materials, such as quartz. Traditional methods for studying the effects of femtosecond laser parameters on the quality of the processed structure mainly use univariate analysis methods, which require large mounts of experiments to predict and achieve the desired experimental results. The method of design of experiments (DOE) provides a way to predict desirable experimental results through smaller experimental scales, shorter experimental periods and lower experimental costs. In this study, a DOE program was designed to investigate the effects of a serious of parameters (laser repetition frequency, pulse energy, scan speed, scan distance, scan mode, scan times and laser focus position) on the depth and roughness (Ra) of the fabricated structure through the liquid-assisted femtosecond laser processing of quartz. A prediction model between the response variables and the main parameters was defined and validated. Finally, several blind holes with a size of 50 × 50 µm2 and a depth of 200 µm were fabricated by the prediction model, which demonstrated the good consistency of the prediction model.

Variable focus convex microlens array on K9 glass substrate based on femtosecond laser processing and hot embossing lithography.

We propose a high-precision method for the fabrication of variable focus convex microlens arrays on K9 glass substrate by combining femtosecond laser direct writing and hot embossing lithography. A sapphire master mold with a blind cylindrical hole array was prepared first by femtosecond laser ablation. The profile control of microlenses dependent on the temperature and the diameter of the blind hole in the sapphire mold was investigated. The curvature radius of the microlens decreased with temperature and increased with diameter. Uniform convex microlens arrays were fabricated with good imaging performance. Further, variable focus convex microlens arrays were fabricated by changing the diameter of the blind hole in sapphire, which produced the image at variable z planes. This method provides a highly precise fabrication of convex microlens arrays and is well suited for batch production of micro-optical elements.

Microstructure and Mechanical Properties of ZrB2⁻HfC Ceramics Influenced by HfC Addition.

ZrB2⁻HfC ceramics have been fabricated using the liquid phase sintering technique at a sintering temperature as low as 1750 °C through the addition of Ni. The effects of HfC addition on the microstructure and mechanical properties of ZrB2⁻based ceramics have been investigated. These ceramics were composed of ZrB2, HfC, Ni, and a small amount of possible (Zr, Hf)B2 solid solution. Small HfC grains were distributed among ZrB2 grain boundaries. These small grains could improve the density of ZrB2⁻based ceramics and play a pinning role. With HfC content increasing from 10 wt % to 30 wt %, more HfC grains were distributed among ZrB2 grain boundaries, leading to weaker interface bonding among HfC grains; the relative density and Vickers hardness increased, and flexural strength and fracture toughness decreased. The weak interface bonding for 20 and 30 wt % HfC contents was the main cause of the decrease in both flexural strength and fracture toughness.

Patient-controlled Intravenous Analgesia With Combination of Dexmedetomidine and Sufentanil on Patients After Abdominal Operation: A Prospective, Randomized, Controlled, Blinded, Multicenter Clinical Study.

OBJECTIVE: To investigate the effect of combination of dexmedetomidine and sufentanil on patient-controlled intravenous analgesia (PCIA) in patients after abdominal operation and to assess the safety and validity of this treatment. METHODS: This is a prospective, randomized controlled, blinded, multicenter clinical study. A total of 210 patients from 9 clinical research centers underwent selective abdominal operation with general anesthesia were enrolled in the study, including laparoscopic-assisted abdominal operation on stomach, intestines or open surgery on stomach, intestines, kidneys and liver, the American Society of Anesthesiologists status I to II. Patients were randomly assigned into 2 groups: control group (group C) sufentanil 100 µg+normal saline 100 mL in total and test group (group D) sufentanil 100 µg+ dexmedetomidine 200 µg+normal saline 100 mL in total. PCIA was set as follow: background infusion of sufentanil 2 µg/h, bolus dose of sufentanil 2 µg, lockout interval 5 minutes. Main measure indices were analgesic consumption, pressing times and effective pressing times of analgesic pump, usage count, and consumption of remedy drug. Validity indices were visual analog scale (VAS) scores and patient satisfaction. Drug safety indices were hemodynamic parameters, drug side effects, and anal exhaust time. RESULTS: In total, 203 cases were analyzed. Seven cases were eliminated for incomplete data record. The total consumption of sufentanil (µg) in 24 hours after operation of group C and group D were 56.9±21.5 and 49.8±15.5, respectively, and the difference was statistically significant (P<0.05). Pressing times of analgesic pump in 24 hours after operation of group C and group D were 9.47±16.07 and 5.02±5.56 times, respectively, and the difference was statistically significant (P<0.05). Effective pressing times of analgesic pump in 24 hours after operation of group C and group D were 7.8±9.7 and 4.57±5.02 times, respectively, and the difference was statistically significant (P<0.05). Resting VAS scores and movement VAS scores at 2, 4, 8, and 24 hours postoperatively were statistically different (P<0.05). Usage times of rescue drug (pethidine) of group C and group D were 9 and 1, mean rank 118.13 and 85.71, respectively, and the difference was statistically significant (P<0.05). Mean rank of general satisfaction of group C and group D were 98.99 and 105.04, respectively, and the difference was statistically significant (P<0.05). Incidence rate of nausea in group C and group D within 24 hours after surgery was 25% and 12.5%, and of vomiting 18.2% and 6.25%, respectively and of vomiting and the difference was statistically significant. CONCLUSIONS: Compared with sufentanil PCIA alone, the combination of dexmedetomidine and sufentanil for PCIA after abdominal operation could reduce sufentanil consumption, decrease VAS scores, lower the rate of nausea and vomiting, and improve patient satisfaction.

Uridine 5'-triphosphate (UTP) protects against cerebral ischemia reperfusion injury in rats.

AIMS: To test the hypothesis that uridine 5'-triphosphate (UTP) had a protective effect on cerebral ischemia reperfusion (IR) injury in rats. METHODS: Ischemia was induced by intraluminal suture of middle cerebral artery occlusion (MCAO). UTP solution was delivered through an indwelling tail venous catheter via microinfusion pump 30 min after the occlusion of MCA at a rate of 0.5 ml/100 g/min. Neurological deficit score (NDS) and brain water content were determined 24 h after reperfusion. Infarct volume was determined by 2,3,5-triphenyl-tetrazolium chloride (TTC) staining and magnetic resonance imaging (MRI), and nerve cell death was studied under an electron microscope. RESULTS: There was a dose-dependent relationship among 10, 30 and 90 microg/kg UTP. The 90 microg/kg UTP had the best protective effect among the 3 groups. We compared 90 microg/kg UTP group with normal saline group and found that UTP had a protective effect on cerebral IR by the results of TTC staining (15.9% vs 30.5%, P<0.01). MRI at 6, 30 and 54 h after reperfusion showed smaller infarct volume in 90 microg/kg group compared with 0 microg/kg group (283.5, 352.1, 367.45 mm(3) vs 401.36, 576.75 and 677.11 mm(3), respectively), and electron microscope showed less nerve cell death in 90 microg/kg group compared with 0 microg/kg group. CONCLUSION: UTP has a dose-dependent protective effect on cerebral IR.