Lumen-apposing metal stents for benign gastrointestinal tract strictures: An international multicenter experience

AIM To investigate technical feasibility, outcomes and adverse events of the lumen-apposing metal stent(LAMS) for benign gastrointestinal(GI) tract strictures.METHODS Between July 2015 and January 2017, patients undergoing treatment by LAMS for benign GI strictures at three tertiary referral centers were included in this study. Primary outcomes included technical success, shortterm clinical success, long-term clinical success, and adverse events. Short-term clinical success was defined as symptom resolution at 30 d after stent placement. Longterm clinical success was defined by symptom resolution at 60 d in patients who continued to have indwelling stent, or continued symptom resolution at 30 d after elective stent removal.RESULTS A total of 21 patients(mean age 62.6 years, 47.6% males) underwent placement of LAMS for benign GI strictures. A 15 mm × 10 mm LAMS was placed in 16 patients, a 10 mm × 10 mm LAMS was placed in 2 patients, and a 16 mm × 30 mm LAMS was placed in 3 patients. Technical success was obtained in all cases. Short-term clinical success was achieved in 19 out of 21 cases(90.5%), and long-term clinical success was achieved in 12 out of 18(66.7%). Mean(range) stent indwell time was 107.2(28-370) d. After a mean(range) dwell time of 104.3(28-306) d, 9 LAMSs were removed due to the following complications: ulceration at stent site(n = 1), angulation(n = 2), migration(n = 4) and stricture overgrowth(n = 2). Migration occurred in 4 cases(19.0%), and it was associated with stricture resolution in one case. Median(range) follow-up period was 119(31-422) d. CONCLUSION Utilization of LAMS for benign strictures has shown to be technically feasible and safe, but adverse events highlight the need for further study of its indications.

CNFET-based voltage rectifier circuit for biomedical implantable applications

Carbon nanotube field effect transistor（CNFET） shows lower threshold voltage and smaller leakage current in comparison to its CMOS counterpart. In this paper, two kinds of CNFET-based rectifiers, full-wave rectifiers and voltage doubler rectifiers are presented for biomedical implantable applications. Based on the standard 32 nm CNFET model, the electrical performance of CNFET rectifiers is analyzed and compared. Simulation results show the voltage conversion efficiency（VCE） and power conversion efficiency（PCE） achieve 70.82% and 72.49% for CNFET full-wave rectifiers and 56.60% and 61.17% for CNFET voltage double rectifiers at typical 1.0 V input voltage excitation, which are higher than that of CMOS design. Moreover, considering the controllable property of CNFET threshold voltage, the effect of various design parameters on the electrical performance is investigated.It is observed that the VCE and PCE of CNFET rectifier increase with increasing CNT diameter and number of tubes. The proposed results would provide some guidelines for design and optimization of CNFET-based rectifier circuits.