Unidirectional barbed suture versus standard monofilament for urethrovesical anastomosis during robotic assisted laparoscopic radical prostatectomy

PURPOSE: V-LocTM180 (Covidien Healthcare, Mansfield, MA) is a new unidirectional barbed suture that may reduce loss of tension during a running closure. We evaluated the use of the barbed suture for urethrovesical anastomosis (UVA) during robotic assisted laparoscopic prostatectomy (RALP). Time to completion of UVA, post-operative anastomotic leak rate, and urinary incontinence were compared in patients undergoing UVA with 3-0 unidirectional-barbed suture vs. 3-0 MonocrylTM (Ethicon, Somerville, NJ). MATERIALS AND METHODS: Data were prospectively collected for 70 consecutive patients undergoing RALP for prostate cancer between November 2009 and October 2010. In the first 35 patients, the UVA was performed using a modified running van Velthoven anastomosis technique using two separate 3-0 monofilament sutures. In the subsequent 35 patients, the UVA was performed using two running novel unidirectional barbed sutures. At 7-12 days postoperatively, all patients were evaluated with a cystogram to determine anastomotic integrity. Urinary incontinence was assessed at two months and five months by total daily pad usage. Clinical symptoms suggestive of bladder neck contracture were elicited. RESULTS: Age, PSA, Gleason score, prostate size, estimated blood loss, body mass index, and clinical and pathologic stage between the 2 groups were similar. Comparing the monofilament group and V-LocTM180 cohorts, average time to complete the anastomosis was similar (27.4 vs. 26.4 minutes, p = 0.73) as was the rate of urinary extravasation on cystogram (5.7 % vs. 8.6%, p = 0.65). There were no symptomatic bladder neck contractures noted at 5 months of follow-up. At 2 months, the percentage of patients using 2 or more pads per day was lower in the V-LocTM180 cohort (24% vs. 44%, p < 0.02). At 5 months, this difference was no longer evident. CONCLUSIONS: Time to complete the UVA was similar in the intervention and control groups. Rates of urine leak were also comparable. While the V-LocTM180 was associated with improved early continence, this difference was transient

Impact of photovoltaic technology and feeder voltage level on the efficiency of façade building-integrated photovoltaic systems

Façade building-integrated photovoltaics is a technology that transforms a passive façade into a distributed, renewable electrical generator by the inclusion of solar cells in the building envelope. Partial shading due to nearby objects is a typical problem for façade building-integrated photovoltaics as it strongly reduces the output power of the installation. Distributed maximum power point tracking by means of embedded converters and a common direct current bus has been proposed to alleviate this issue. However, the bus voltage plays an important role in converter topology selection and overall efficiency, although this is not being covered in literature. Also the influence of the solar cell technology on the output voltage of the module is not studied before, although it strongly influences the converter topology selection and the losses. In this paper, a methodology is described to investigate the influence of the voltage level and solar cell technology by taking conversion losses in the converters and the cabling into account. The methodology is applied to two case study buildings for which four different cell technologies are considered. It is shown that overall high efficiencies are obtained, regardless of the voltage level. However, the loss distribution changes significantly with the voltage. This aspect can be used advantageously to reduce thermal stresses on the embedded converter. Furthermore, the overall system efficiency is typically higher when the voltage step-up is lower.</p

Impact of photovoltaic technology and feeder voltage level on the efficiency of facade building-integrated photovoltaic systems

status: publishe

Impact of photovoltaic technology and feeder voltage level on the efficiency of façade building-integrated photovoltaic systems

Façade building-integrated photovoltaics is a technology that transforms a passive façade into a distributed, renewable electrical generator by the inclusion of solar cells in the building envelope. Partial shading due to nearby objects is a typical problem for façade building-integrated photovoltaics as it strongly reduces the output power of the installation. Distributed maximum power point tracking by means of embedded converters and a common direct current bus has been proposed to alleviate this issue. However, the bus voltage plays an important role in converter topology selection and overall efficiency, although this is not being covered in literature. Also the influence of the solar cell technology on the output voltage of the module is not studied before, although it strongly influences the converter topology selection and the losses. In this paper, a methodology is described to investigate the influence of the voltage level and solar cell technology by taking conversion losses in the converters and the cabling into account. The methodology is applied to two case study buildings for which four different cell technologies are considered. It is shown that overall high efficiencies are obtained, regardless of the voltage level. However, the loss distribution changes significantly with the voltage. This aspect can be used advantageously to reduce thermal stresses on the embedded converter. Furthermore, the overall system efficiency is typically higher when the voltage step-up is lower.Photovoltaic Materials and Device