An Experiment-Based Profile Function for the Calculation of Damage Distribution in Bulk Silicon Induced by a Helium Focused Ion Beam Process.

The helium focused ion beam (He-FIB) is widely used in the field of nanostructure fabrication due to its high resolution. Complicated forms of processing damage induced by He-FIB can be observed in substrates, and these damages have a severe impact on nanostructure processing. This study experimentally investigated the influence of the beam energy and ion dose of He-FIB on processing damage. Based on the experimental results, a prediction function for the amorphous damage profile of the single-crystalline silicon substrate caused by incident He-FIB was proposed, and a method for calculating the amorphous damage profile by inputting ion dose and beam energy was established. Based on one set of the amorphous damage profiles, the function coefficients were determined using a genetic algorithm. Experiments on single-crystalline silicon scanned by He-FIB under different process parameters were carried out to validate the model. The proposed experiment-based model can accurately predict the amorphous damage profile induced by He-FIB under a wide range of different ion doses and beam energies.

Continuous cellular automaton simulation of focused ion beam-induced deposition for nano structures.

With the assistance of a gas injection system, focused ion beam-induced deposition (FIBID) can be realized to fabricate complicated three-dimensional structures in nanoscale. The growth rate of the deposited structure depends on the flux of precursor gas and incident ions. In this study, a Continuous Cellular Automaton (CCA) model is put forward to simulate the FIBID process, with four rules established to initiate and dominate the interface evolution, which can calculate the deposited structure profile under different fabrication conditions. In this model, the sputtering and diffusion effects are taken into account to establish a more accurate relationship between the deposition rate and precursor gas flux based on the continuous model, and the influences imposed by precursor gas and incident ions are clarified. In order to verify the precursor gas distribution and the growth mechanism of the FIBID, experiments are carried out with different local precursor gas flux on the substrate surface with a 7 pA and 30 keV Ga ions, using C9H16Pt as the precursor gas. The experimental and simulation results indicate that the CCA model features a high accuracy in predicting the deposited structure profile, and prove that the proposed model can be utilized in fabrication parameters optimization.

[Melatonin receptor 2 mediated spinal dorsal horn astrocytes IL-17 inhibition contributes to electroacupuncture analgesia in neuropathic pain rats].

OBJECTIVE: To investigate the effect of electroacupuncture (EA) on pain behaviors and expression of spinal dorsal horn melatonin receptor 2 (MT2) and interleukin-17 (IL-17) in neuropathic pain rats, so as to explore its mechanism underlying pain relief. METHODS: The present study includes 3 parts. In the first part, eighteen male SD rats were randomly divided into 3 groups: sham operation, model and EA groups, with 6 rats in each group. The neuropathic pain model was established by chronic constriction injury (CCI) of the right sciatic nerve. On the 7th day following modeling, EA was applied to the right "Zusanli" (ST36) and "Sanyinjiao" (SP6) (1 mA,2 Hz/100 Hz) for 30 min. The mechanical pain threshold(MWT) and thermal pain thre-shold(TPT) of the affected limb were detected before modeling, 7 days following modeling and 60 min after EA. The expression of MT2 in spinal dorsal horn was detected by Western blot. The contents of melatonin （Mel） and IL-17 in the spinal dorsal horn were determined by ELISA. The expression of glial fibrillary acidic protein (GFAP) in the spinal dorsal horn was determined by Western blot and immunohistochemistry. In the second part, 30 rats were divided into 5 groups: sham operation, model, EA, MT2 antagonist (4-P-PDOT), and dimethyl sulfoxide (DMSO) groups, with 6 rats in each group. Rats of the 4-P-PDOT and DMSO groups were intrathecal injection with 10 µL MT2 antagonist 4-P-PDOT (100 µg) and equivalent DMSO 30 min before EA. The MWT and TPT of affected limb were detected. The GFAP expression and IL-17 content in the spinal dorsal horn was detected by Western blot， immunohistochemistry and ELISA, respectively. In the third part, 30 rats were randomly divided into 5 groups: sham operation, model, EA, recombinant IL-17, and normal saline groups, with 6 rats in each group. The recombinant IL-17 protein (100 ng, 10 µL) and the same amount of 0.9% sodium chloride solution were intrathecal injection into the rats of the recombinant IL-17 group and the normal saline group 30 min before the EA. The MWT and TPT of affected limb were measured. RESULTS: On the 7th day after modeling, the MWT of rats in the model group and the EA group were significantly higher, while TPT were lower than those before the modeling (P<0.05). At 60 min after EA, compared with the model group, the MWT and TPT of the EA group reversed significantly (P<0.05). The levels of GFAP and IL-17 were significantly increased, while the levels of Mel and MT2 were significantly decreased in the model group than in the sham operation group (P<0.05), and those were considerably reversed in the EA group than in the model group (P<0.05). Compared with the EA and DMSO groups, the MWT in the 4-P-PDOT group were significantly increased, while TPT were decreased (P<0.05), and the contents of GFAP and IL-17 were significantly increased (P<0.05). Compared to the EA and normal saline groups, MWT of the rats in the recombinant IL-17 group were significantly increased, while TPT decreased (P<0.05). CONCLUSION: EA of ST36 and SP6 can alleviate neuropathic pain in CCI rats, which is closely related to its effect in inhibiting the release of IL-17 from astrocytes mediated by MT2.

[Optimal dose of local anesthetic mixture in ultrasound-guided infraclavicular brachial plexus block via coracoid approach: analysis of 160 cases].

OBJECTIVE: To investigate the optimal dose of local anesthetic mixture in ultrasound-guided infraclavicular brachial plexus block via coracoid approach. METHODS: 160 patients scheduled for surgery of the hand or forearm were randomly divided into 4 equal groups (Groups A, B, C, and D). To receive 8, 7, 6, or 5 ml of anesthetic mixture of 0.75% ropivacaine and 2% lidocaine for radial nerve, axillary nerve, median nerve, ulnar nerve, median cutaneous nerve of arm, median antebrachial cutaneous nerve, and lateral antebrachial cutaneous nerve respectively ultrasound-guided infraclavicular brachial plexus block via coracoid approach. The time for anesthesia taking effect, anesthesia maintenance time, and quality of sensory block were observed. RESULTS: Anesthesia took effect about 4 minutes after injection in these 4 groups without significant differences among then (all P > 0.05). The good analgesic effect rates of Groups A, B, and C were all 100%, all significantly higher than that of Group D (87.5%, P = 0.027). The block maintenance times of Groups A, B, and C were (377 +/- 111) min, (369 +/- 135) min, and (351 +/- 112) min respectively, all significantly longer than that of Group D [(296 +/- 101) min, P = 0.024]. No anesthesia-related complication was found in these 4 groups. CONCLUSION: Ultrasound-guided infraclavicular brachial plexus block via coracoid approach can reduce the volume of local anesthetic mixture. The dose of 6 ml local anesthetic mixture for each nerve fascicle, totally 18 ml, provides good analgesic effect and does not seem to affect the time for anesthesia taking effect.