Gallium Phosphide photoanode coated with TiO2 and CoOx for stable photoelectrochemical water oxidation.

Gallium Phosphide (GaP) has a band gap of 2.26 eV and a valance band edge that is more negative than the water oxidation level. Hence, it may be a promising material for photoelectrochemical water splitting. However, one thing GaP has in common with other III-V semiconductors is that it corrodes in photoelectrochemical reactions. Cobalt oxide (CoOx) is a chemically stable and highly active oxygen evolution reaction co-catalyst. In this study, we protected a GaP photoanode by using a 20 nm TiO2 as a protection layer and a 2 nm cobalt oxide co-catalyst layer, which were both deposited via atomic layer deposition (ALD). A GaP photoanode that was modified by CoOx exhibited much higher photocurrent, potential, and photon-to-current efficiency than a bare GaP photoanode under AM1.5G illumination. A photoanode that was coated with both TiO2 and CoOx layers was stable for over 24 h during constant reaction in 1 M NaOH (pH 13.7) solution under one sun illumination.

Self-planarized quantum-disks-in-nanowires ultraviolet-B emitters utilizing pendeo-epitaxy.

The growth of self-assembled, vertically oriented and uniform nanowires (NWs) has remained a challenge for efficient light-emitting devices. Here, we demonstrate dislocation-free AlGaN NWs with spontaneous coalescence, which are grown by plasma-assisted molecular beam epitaxy on an n-type doped silicon (100) substrate. A high density of NWs (filling factor >95%) was achieved under optimized growth conditions, enabling device fabrication without planarization using ultraviolet (UV)-absorbing polymer materials. UV-B (280-320 nm) light-emitting diodes (LEDs), which emit at ∼303 nm with a narrow full width at half maximum (FWHM) (∼20 nm) of the emission spectrum, are demonstrated using a large active region ("active region/NW length-ratio" ∼50%) embedded with 15 stacks of AlxGa1-xN/AlyGa1-yN quantum-disks (Qdisks). To improve the carrier injection, a graded layer is introduced at the AlGaN/GaN interfaces on both p- and n-type regions. This work demonstrates a viable approach to easily fabricate ultra-thin, efficient UV optoelectronic devices on low-cost and scalable silicon substrates.

Optimization of polyvinylidene fluoride (PVDF) membrane fabrication for protein binding using statistical experimental design.

Statistical experimental design was employed to optimize the preparation conditions of polyvinylidenefluoride (PVDF) membranes. Three variables considered were polymer concentration, dissolving temperature, and casting thickness, whereby the response variable was membrane-protein binding. The optimum preparation for the PVDF membrane was a polymer concentration of 16.55 wt%, a dissolving temperature of 27.5°C, and a casting thickness of 450 µm. The statistical model exhibits a deviation between the predicted and actual responses of less than 5%. Further characterization of the formed PVDF membrane showed that the morphology of the membrane was in line with the membrane-protein binding performance.

Simultaneous quantum dash-well emission in a chirped dash-in-well superluminescent diode with spectral bandwidth >700 nm.

We report on the quantitative evidence of simultaneous amplified spontaneous emission from the AlGaInAs/InAs/InP-based quantum-well (Qwell) and quantum-dashes (Qdash) in a multistack dash-in-an-asymmetric-well superluminescent diode heterostructure. As a result, an emission bandwidth (full width at half-maximum) of >700 nm is achieved, covering entire O-E-S-C-L-U communication bands, and a maximum continuous wave output power of 1.3 mW, from this device structure. This demonstration paves a way to bridge entire telecommunication bands through proper optimization of device gain region, bringing significant advances and impact to a variety of cross-disciplinary field applications.

Effect of the number of stacking layers on the characteristics of quantum-dash lasers.

A theoretical model is evaluated to investigate the characteristics of InAs/InP quantum dash (Qdash) lasers as a function of the stack number. The model is based on multimode carrier-photon rate equations and accounts for both inhomogeneous and homogeneous broadenings of the optical gain. The numerical results show a non monotonic increase in the threshold current density and a red shift in the lasing wavelength on increasing the stack number, which agrees well with reported experimental results. This observation may partly be attributed to an increase of inhomogeneity in the active region.

418 cases of laparoscopic colorectal resections: a single-institution experience and literature review.

INTRODUCTION: Evidence from randomised controlled trials has shown that laparoscopic colon and rectal cancer resection not only confers short-term benefits but also does not differ considerably in terms of its long-term oncological outcomes, as compared with open surgery. METHODS: All laparoscopic colon and rectal resections performed between January 2005 and December 2007 were included. Patient records were reviewed from a prospective database and the relevant clinical data was obtained, with a subgroup analysis of cancer procedures performed. RESULTS: 418 patients (247 male), median age 63 years (range 24 to 88), underwent laparoscopic resection of the colon and rectum. The median Body Mass Index (BMI) was 22.5 (range 13.5 to 39.3). The majority of the procedures were performed for malignant disease (81.3 percent) and the most common procedure was anterior resection (79.4 percent). The median duration of surgery was 135 minutes (range 65 to 330), with conversions to open surgery in 44 patients (10.5 percent). Complications occurred in 78 patients (18.7 percent), including anastomotic leaks in five (1.20 percent). The median length of hospital stay was five days (range 3 to 90) and the median follow-up was 19 months (range 1 to 46). In the 340 patients with malignant disease, the median number of lymph nodes harvested was 13 (range 5 to 48), and at the latest review, 230 patients (67.6 percent) were disease-free, with locoregional recurrence in 2.9 percent and systemic recurrence in 10 percent. CONCLUSION: To date, this is the largest series of laparoscopic colorectal resections reported locally, and our results show that it is safe, feasible and produces favourable results.

Radiation proctitis: a decade's experience.

INTRODUCTION: Pelvic radiotherapy is an essential component of potentially curative therapy for many pelvic malignancies; however, the rectum consequently often sustains collateral injury. METHODS: The researchers retrieved patient data that was prospectively gathered over a ten-year period between January 1995 and December 2004. The relevant details, including gender, age, pelvic pathology for which radiotherapy was administered, the presenting symptoms, the interval between radiotherapy and the onset of symptoms, the mode of diagnosis, treatments received, length of hospital stay and duration of follow-up, were analysed. RESULTS: During the period under review, 77 patients were admitted for the treatment of radiation proctitis, with a median follow-up period of 14 (range 1-61) months. There were 23 male and 54 female patients, with a median age of 63.9 (range 37-89) years. The most common underlying cancers were gynaecological (63.6 percent), prostate (18.2 percent) and colorectal (15.6 percent) cancer. The most common presenting symptom was bleeding per rectum (89.6 percent), with a change in bowel habits a distant second (10.4 percent). The median latent period between the completion of radiotherapy and the onset of symptoms was 24 (range 3-68) months. The majority of the patients (72.5 percent) received non-surgical treatment, most commonly using topical 4 percent formalin solution to arrest the bleeding, with more than half the patients requiring repeat treatments. 14 (18.2 percent) patients required colorectal resections for intractable bleeding, intestinal obstruction or intra-abdominal sepsis. CONCLUSION: Radiation proctitis can be a therapeutic challenge, even in the most experienced hands. The majority of patients who present with per rectal bleeding can be treated using topical modalities, while surgery may offer the only chance of relief from life-threatening symptoms.

Optical injection modulation of quantum-dash semiconductor lasers by intra-cavity stimulated Raman scattering.

We report the optical injection modulation of semiconductor lasers by intra-cavity stimulated Raman scattering. This mechanism manifests itself as sharply enhanced modulation bandwidth in InAs/InGaAlAs/InP quantum-dash lasers when the injected photons are 33 +/- 3 meV more energetic than the lasing photons. Raman scattering measurements on the quantum-dash structure and rate equation models strongly support direct gain modulation by stimulated Raman scattering. We believe this new bandwidth enhancement mechanism may have important applications in optical communication and signal processing.

Robotic-assisted surgery for low rectal dissection: from better views to better outcome.

INTRODUCTION: The use of robotics in colorectal surgery is relatively new. The first few cases of colonic surgery using da Vinci Surgical System were reported in 2002. Since then, several centres had reported on their experience, with favourable outcomes. Our department started to embark on robotics in colorectal surgery in December 2007. The aim of our paper was to share our early experience with robotics in colorectal surgery and provide an update on the current status of robotics. METHODS: Preparations included formal training with the da Vinci Surgical System, certification of the surgeons, and obtaining Hospital Ethics committee approval. We used a hybrid technique of laparoscopic and robotic assistance in the resection of mid- to low-rectal cancer (total mesorectal excision). Laparoscopic approach was used to isolate the inferior mesenteric artery and for mobilisation of the left colon. The da Vinci robot was used in the dissection of the rectum down to the pelvic floor. We reviewed the outcomes of our early experience with emphasis on feasibility and safety. RESULTS: Over a period of three months, we performed eight cases of robotic-assisted colorectal surgery for cancer. The median age of the patients was 55 (range 42-80) years. The median operating time was 192.5 (range 145-250) minutes. There were no intraoperative or postoperative complications related to the use of robotics. The median length of hospital stay was five (range 4-30) days. CONCLUSION: Robotic-assisted laparoscopic colorectal surgery is a safe and feasible procedure.

Colorectal cancer mass screening event utilising quantitative faecal occult blood test.

INTRODUCTION: Colorectal cancer (CRC) is a leading cause of morbidity and mortality with human and financial costs. Screening by faecal occult blood test (FOBT) has proven to be effective in decreasing mortality from CRC in both randomised trials and case-control studies. We report on the results of a CRC screening event using quantitative FOBT (QFOBT) held in Singapore. METHODS: The mass screening event was held over two days, and participants 40 years or older without prior screening performed in the preceding year were eligible. Those with significant symptoms or medical comorbidities were excluded. Stool sampling was done with two issued immunochemical QFOBT kits, and participants with positive stool samples with equal or greater than 100 ng haemoglobin/ml sample solution in any two samples were advised to have a colonoscopy screening conducted. RESULTS: A total of 1,048 participants took part in the screening event. 222 (21 percent) of the participants claimed to have some abdominal symptoms prior to screening. 49 participants (26 males, 23 females) tested positive for QFOBT and 47 were evaluated. 10 (21 percent) had polyps and one case of colorectal cancer was detected. Seven of these cases had significant neoplasia (lesions 1 cm or larger) and were treated. Two patients required surgery. CONCLUSION: Our study demonstrates wide variation in the attitudes of participants who turned up for screening. In addition, the number of significant colorectal neoplasia patients (14 percent) in those with positive QFOBT provides further evidence of the importance of screening with a potential reduction in CRC mortality. Continuous education of the public in events such as this, is essential to improving attitudes towards screening.

Laparoscopic high anterior resection with natural orifice specimen extraction (NOSE) for early rectal cancer.

Laparoscopic surgery for colorectal cancer requires an abdominal incision to extract the resected specimen. We describe a technique for laparoscopic resection of an early-stage upper rectal cancer in a 51-year-old man followed by transanal specimen delivery, hence avoiding the need for making any additional abdominal incisions for retrieval of the specimen. Pneumoperitoneum was created, followed by medial-tolateral mobilization of the sigmoid colon, and take down of the splenic flexure and division of the inferior mesenteric vessels laparoscopically. The upper rectum distal to the tumour and proximal colon was transected with a laparoscopic stapler. The specimen was retrieved transanally via an opening in the rectal stump. The proximal colon was then delivered transanally and the anvil of the circular stapler inserted before returning it to the pelvic cavity. The rectal stump was transected again just below the opening to close off the stump, and the colorectal anastomosis was then completed intracorporeally. The patient, a 51-year-old male (BMI 18.6 kg/m(2)) with a 2.5-cm, early-stage posterior rectal cancer 12 cm from the anal verge, underwent the above-described procedure. Postoperative recovery was uneventful. He resumed normal daily activities 1 week after surgery. Histology confirmed a T1N0 upper rectal cancer. In the effort to minimize surgical trauma and postoperative pain, natural orifice specimen extraction techniques have been attempted. This procedure may be applicable to benign tumours and early colorectal cancer, and serves as an intermediate step between laparoscopic and natural orifice surgery.

A 6-year review of surgical morbidity and oncological outcome after high anterior resection for colorectal malignancy with and without splenic flexure mobilization.

OBJECTIVE: High anterior resection (HAR) for colorectal cancer is traditionally performed with routine mobilization of the splenic flexure. This is a retrospective review of mortality and morbidity following HAR in which the splenic flexure has been preserved. METHOD: From a prospective database, all patients who had undergone elective HAR for colorectal cancer between 1999 and 2005 were identified. Morbidity, mortality, pathology and survival data for patients having HAR with and without splenic flexure mobilization were analysed. RESULTS: A total of 707 patients were identified. Five hundred and thirty-one had HAR with preservation of the splenic flexure. In these patients outcome was: anastomotic leak (0.4%), wound infection (3.6%), anastomotic stricture (0.4%) and 30-day mortality (0.9%). No statistical significant difference was found for postoperative morbidity (P = 0.1926), 30-day mortality (P =0.3285), lymph node harvest (P = 0.2127) or survival (P = 0.1457) compared with patients in whom the splenic flexure was mobilized. Longitudinal resection margins were greater following HAR with splenic flexure mobilization (P < 0.0001). CONCLUSION: No morbidity, oncological or survival disadvantage in performing splenic flexure preserving HAR was found.

A prospective study assessing anal plug for containment of faecal soilage and incontinence.

OBJECTIVE: Faecal incontinence is a common and embarrassing problem for many individuals. Some patients remained symptomatic despite the availability of different treatments. There is a limited range of commercially available products designed to cope with faecal incontinence. The anal plug has been developed to contain the loss of stool. This study aimed to evaluate the use of anal plug in Asian patients with intractable faecal soilage and incontinence judged by clinical and functional outcomes. METHOD: A prospective study of consecutive patients with intractable faecal incontinence was carried out. Suitable patients tested the anal plug for 3 weeks. They completed a structured questionnaire on its use including the ASCRS quality of life questionnaire for faecal incontinence. RESULTS: Thirty patients, median age 63 (interquartile range 52-70) years, participated in the trial. Nineteen of 30 patients were comfortable wearing the plug, seven patients withdrew from the study because of discomfort, and four had tolerable discomfort and managed to complete the trial protocol. Patients who tolerated the plug found that it was highly successful in controlling faecal incontinence. Twenty-one of 30 patients wished to continue to use the plug regularly after the study. There was a trend toward improvement in quality of life scores during the study. CONCLUSION: The anal plug was effective in containing faecal incontinence and was well tolerated in the majority of patients selected for this treatment.

Comparison of forearm and conventional Bier's blocks for manipulation and reduction of distal radius fractures.

Forearm-based Bier's block has been advocated as a useful anaesthesic technique in hand surgery. However, there is limited data comparing forearm blocks with the conventional Bier's block. We conducted a randomised controlled trial (n=30) comparing the two techniques of anaesthesia for manipulation and reduction of closed distal radius fractures in an emergency room setting. Pain scores measured using the Visual Analogue Scale during the procedure were used as the primary outcome assessment. There was no significant difference in pain scores between the forearm and conventional Bier's block (mean VAS 18.4 SD 22.10 versus 33.7 SD 29.6). No major complications were observed in either group. The forearm-based Bier block is an effective alternative to the conventional block.

Room-temperature broadband emission of an InGaAs/GaAs quantum dots laser.

We report the first demonstration to our knowledge of an ultrabroad emission laser using InGaAs/GaAs quantum dots by cycled monolayer deposition. The device exhibits a lasing wavelength coverage of approximately 40 nm at an approximately 1160 nm center wavelength at room temperature. The broadband signature results from the superposition of quantized lasing states from highly inhomogeneous dots.

Prospective randomized crossover trial comparing fibre with lactulose in the treatment of idiopathic chronic constipation.

BACKGROUND: Fibre is often recommended as the first-choice treatment but its effects can be uneven. The aim of the study was to compare the clinical efficacy and tolerability of fibre versus lactulose in outpatients with chronic constipation. METHODS: In a prospective randomized crossover trial, patients were randomized to receive fibre or lactulose for four weeks. Between treatments, patients had at least one week free of laxatives. RESULTS: 50 patients, of median age 50 years (range, 18-85) were recruited and 39 patients completed the trial. Compared to fibre, lactulose resulted in significantly higher mean bowel frequency (7.3, 95% CI 5.7 to 8.9 vs. 5.5, 95% CI 4.4 to 6.5; p=0.001) and stool consistency score (3.4, 95% CI 3.1 to 3.7 vs. 2.9, 95% CI 2.5 to 3.3; p=0.018). Scores for ease of evacuation were similar. The frequencies of adverse effects were not significantly different, but greater in the lactulose group. Mean patients' recorded improvement score was significantly higher after taking lactulose than fibre (6.2, 95% CI 5.5 to 7.0 vs. 4.8, 95% CI 4.0 to 5.9; p=0.017). Of the 39 patients who completed the trial, 24 (61.5%) preferred lactulose and 14 (35.9%) preferred fibre. CONCLUSIONS: Lactulose had better efficacy than fibre for chronic constipation in ambulant patients, although both treatments were equally well tolerated in terms of adverse effects.

PPH03 stapled hemorrhoidopexy: our experience.

BACKGROUND: Stapled hemorrhoidopexy is an established treatment for hemorrhoidal disease. We evaluated our experience with stapled hemorrhoidopexy using the new Procedure for Prolapse and Hemorrhoids (PPH03) Proximate HCS hemorrhoidal circular stapler (Ethicon Endo-Surgery). METHODS: We retrospectively reviewed clinical data for 238 patients who had undergone stapled hemorrhoidopexy in our department over a 2-month period. Patients were followed-up for a median of 3.5 weeks (range, 1-11 weeks) and were analyzed for complications and resolution of symptoms. RESULTS: The hemorrhoids treated were third- and fourth-degree, as well as second degree (after failure of other therapies). Mean duration of surgery was 12.7 minutes (range, 5-20 minutes) and the majority of patients was treated with an ambulatory procedure. Most patients were discharged within 6 hours after surgery. On follow-up, 3.7% of patients had minor complaints after surgery. Technically, the new PPH03 stapler device has a quickclose knob, which allows rapid opening and closing. The closed staple height of 0.75 mm increases staple line compression on tissue and key blood vessels, hence minimizing bleeding. Prior to this, stapled hemorrhoidopexy was done using the PPH01 device. CONCLUSIONS: Stapled hemorrhoidopexy using the new PPH03 stapler is a safe, short and effective procedure in the management of hemorrhoids. It can be done in the ambulatory setting and patients have few postoperative complications.

Experience of 3711 stapled haemorrhoidectomy operations.

BACKGROUND: Stapled haemorrhoidectomy has been routinely performed in the Department of Colorectal Surgery, Singapore General Hospital since 1999. METHODS: A retrospective review was undertaken of all patients who underwent stapled haemorrhoidectomy between October 1999 and May 2004. The outcomes studied were patient profiles, priority of operation, indications for surgery, length of operation, postoperative complications and recurrences. RESULTS: A total of 3711 patients (51.1 per cent women) had the surgery. The median patient age was 50 (range 18-88) years. The main indications were bleeding (80.7 per cent), haemorrhoidal prolapse (59.6 per cent) and thrombosis (3.9 per cent). The median duration of operation was 15 (range 5-45) min. Minor complications occurred in 12.3 per cent of patients: acute retention of urine (4.9 per cent), bleeding (4.3 per cent), significant postoperative pain requiring admission (1.6 per cent), anorectal stricture (1.4 per cent), perianal haematoma (0.05 per cent) and significant residual skin tags (0.05 per cent). One patient developed a perianal abscess after stapled haemorrhoidectomy. Anastomotic dehiscence occurred in three patients (0.08 per cent). Twelve (0.3 per cent) patients had a recurrence at a median of 16 (range 5-45) months. CONCLUSION: Considerable experience of stapled haemorrhoidectomy confirms it as a safe and effective procedure.