Synthesis of Polycyclic Olefinic Monomers from Norbornadiene for Inverse Vulcanization: Structural and Mechanistic Consequences.

The preparation of high-sulfur content organosulfur polymers has generated considerable interest as an emerging area in polymer science that has been driven by advances in the inverse vulcanization polymerization of elemental sulfur with organic comonomers. While numerous new inverse vulcanized polysulfides have been made over the past decade, insights into the mechanism of inverse vulcanization and structural characterization of the high-sulfur-content copolymers remain limited in scope. Furthermore, the exploration of new molecular architectures for organic comonomer synthesis remains an important frontier to enhance the properties of these new polymeric materials. In the current report, the first detailed study on the synthesis and inverse vulcanization of polycyclic rigid comonomers derived from norbornadiene was conducted, affording a quantitative assessment of polymer microstructure for these organopolysulfides and insights into the inverse vulcanization polymerization mechanism for this class of monomers. In particular, a stereoselective synthesis of the endo-exo norbornadiene cyclopentadiene adduct (Stillene) was achieved, which enabled direct comparison with the known exo-exo norbornadiene dimer (NBD2) previously used for inverse vulcanization. Reductive degradation of these sulfur copolymers and detailed structural analysis of the recovered sulfurated organic fragments revealed that remarkable exo-stereospecificity was achieved in the inverse vulcanization of elemental sulfur with both these polycyclic dienyl comonomers, which correlated to the robust thermomechanical properties associated with organopolysulfides made from NBD2 previously. Melt processing and molding of these sulfur copolymers were conducted to fabricate free-standing plastic lenses for long-wave infrared thermal imaging.

Synthesis of Deuterated and Sulfurated Polymers by Inverse Vulcanization: Engineering Infrared Transparency via Deuteration.

The synthesis of deuterated, sulfurated, proton-free, glassy polymers offers a route to optical polymers for infrared (IR) optics, specifically for midwave IR (MWIR) photonic devices. Deuterated polymers have been utilized to enhance neutron cross-sectional contrast with proteo polymers for morphological neutron scattering measurements but have found limited utility for other applications. We report the synthesis of perdeuterated d14-(1,3-diisopropenylbenzene) with over 99% levels of deuteration and the preparation of proton-free, perdeuterated poly(sulfur-random-d14-(1,3-diisopropenylbenzene)) (poly(S-r-d14-DIB)) via inverse vulcanization with elemental sulfur. Detailed structural analysis and quantum computational calculations of these reactions demonstrate significant kinetic isotope effects, which alter mechanistic pathways to form different copolymer microstructures for deutero vs proteo poly(S-r-DIB). This design also allows for molecular engineering of MWIR transparency by shifting C-H bond vibrations around 3.3 µm/3000 cm-1 observed in proteo poly(S-r-DIB) to 4.2 µm/2200 cm-1. Furthermore, the fabrication of thin-film MWIR optical gratings made from molding of deuterated-sulfurated, proton-free poly(S-r-d14-DIB) is demonstrated; operation of these gratings at 3.39 µm is achieved successfully, while the proteo poly(S-r-DIB) gratings are opaque at these wavelengths, highlighting the promise of MWIR sensors and compact spectrometers from these materials.

Sulfenyl Chlorides: An Alternative Monomer Feedstock from Elemental Sulfur for Polymer Synthesis.

A polymerization methodology is reported using sulfur monochloride (S2Cl2) as an alternative feedstock for polymeric materials. S2Cl2 is an inexpensive petrochemical derived from elemental sulfur (S8) but has numerous advantages as a reactive monomer for polymerization vs S8. This new process, termed sulfenyl chloride inverse vulcanization, exploits the high reactivity and miscibility of S2Cl2 with a broad range of allylic monomers to prepare soluble, high molar-mass linear polymers, segmented block copolymers, and crosslinked thermosets with greater synthetic precision than achieved using classical inverse vulcanization. This step-growth addition polymerization also allows for preparation of a new class of thiol-free, inexpensive, highly optically transparent thermosets (α = 0.045 cm-1 at 1310 nm), which exhibit among the best optical transparency and low birefringence relative to commodity optical polymers, while possessing a higher refractive index (n > 1.6) in the visible and near-infrared spectra. The fabrication of large-sized optical components is also demonstrated.

Low-cost, chromatic confocal endomicroscope for cellular imaging in vivo.

We have developed a low-cost, chromatic confocal endomicroscope (CCE) that can image a cross-section of the tissue at cellular resolution. In CCE, a custom miniature objective lens was used to focus different wavelengths into different tissue depths. Therefore, each tissue depth was encoded with the wavelength. A custom miniature spectrometer was used to spectrally-disperse light reflected from the tissue and generate cross-sectional confocal images. The CCE prototype had a diameter of 9.5 mm and a length of 68 mm. Measured resolution was high, 2 µm and 4 µm for lateral and axial directions, respectively. Effective field size was 468 µm. Preliminary results showed that CCE can visualize cellular details from cross-sections of the tissue in vivo down to the tissue depth of 100 µm.

Thermal compensation of molded silicone optics.

Optical grade silicone has various properties that make it attractive for solar concentrators, such as excellent transmission across the solar spectrum and flexible moldability for freeform profiles. In this study, a glass-silicone lens structure is proposed to reduce the optothermal effect on the silicone lens. Experimental measurements and simulation modeling results demonstrate that the focal length sensitivity of the glass-silicone lens with respect to temperature can be reduced by a factor of 10 when compared to a silicone lens alone. This model has been extended to the simulation of a proposed two-stage silicone solar concentrator, consisting of an array of acylindrical lenslets and rows of waveguides that focus light onto microphotovoltaic cells. The optical efficiency of the solar concentration system showed a change of less than 10% compared to the efficiency at room temperature for temperature changes from -10∘C to 70°C.

Microfabrication of a color filter array utilizing colored SU-8 photoresists.

Patterned color filter arrays are important components in digital cameras, camcorders, scanners, and multispectral detection and imaging instruments. In addition to the rapid and continuous progress to improve camera resolution and the efficiency of imaging sensors, research into the design of color filter arrays is important to extend the imaging capability beyond conventional applications. This paper reports the use of colored SU-8 photoresists as a material to fabricate color filter arrays. Optical properties, fabrication parameters, and pattern spatial resolution are systematically studied for five color photoresists: violet, blue, green, yellow, and red. An end-to-end fabrication process is developed to realize a five-color filter array designed for a wide angle multiband artificial compound eye camera system for pentachromatic and polarization imaging. Colored SU-8 photoresists present notable advantages, including patternability, color tunability, low-temperature compatibility, and process simplicity. The results regarding the optical properties and the fabrication process for a colored SU-8 photoresist provide significant insight into its usage as an optical material to investigate nonconventional color filter designs.

Prophylactic clip application for large pedunculated polyps before snare polypectomy may decrease immediate postpolypectomy bleeding.

BACKGROUND: Although prophylactic clip application before polypectomy may prevent postpolypectomy bleeding (PPB), the usefulness of prophylactic clipping in the treatment of large pedunculated polyps is controversial in some prospective randomized studies. This study was conducted to evaluate the efficacy of prophylactic clip application and to investigate the predictors of PPB in large pedunculated colorectal polyps. METHODS: A total of 137 pedunculated polyps (size ≥1 cm) in 116 patients were prospectively included and randomized into group A (with clipping) and group B (without clipping), and resected. The occurrences of immediate PPB (graded 1-4) and delayed PPB were compared. RESULTS: Sixty-seven polyps were allocated in group A and 70 polyps in group B. In both groups, the median polyp diameter was 15 mm (P = 0.173) and the median stalk diameter was 3 mm (P = 0.362). Twenty-eight (20.4%) immediate PPB episodes in 137 polyps occurred, 6 (9.0%) in group A and 22 (31.4%) in group B (P = 0.001). However, the occurrence of delayed PPB was not different between the groups (P = 0.943). Prophylactic clip application decreased the occurrence of immediate PPB (odds ratio 0.215, 95% confidence interval 0.081-0.571). Moreover, polyp size ≥20 mm and stalk diameter ≥ 4 mm increased the risk of immediate PPB. CONCLUSIONS: Clip application before polypectomy of ≥1 cm pedunculated polyps is effective in decreasing the occurrence of immediate PPB. Thus, clip application should be considered before performing snare polypectomy, especially for large polyps with a thick stalk. TRIAL REGISTRATION: This research was studied a prospective maneuver and enrolled in a registry of clinical trials run by United States National Library of Medicine at the National Institutes of Health (ClinicalTrials.gov Protocol Registration and Results system ID: NCT01437631). This study was registered on September 19, 2011.

Comparison of small bowel findings using capsule endoscopy between Crohn's disease and intestinal tuberculosis in Korea.

BACKGROUND: Little is known about capsule endoscopy (CE) findings in patients with intestinal tuberculosis who exhibit small bowel lesions. The aim of the present study was to distinguish between Crohn's disease (CD) and intestinal tuberculosis based on CE findings. METHODS: Findings from 55 patients, who underwent CE using PillCam SB CE (Given Imaging, Yoqneam, Israel) between February 2003 and June 2015, were retrospectively analyzed. RESULTS: CE revealed small bowel lesions in 35 of the 55 patients: 19 with CD and 16 with intestinal tuberculosis. The median age at diagnosis for patients with CD was 26 years and 36 years for those with intestinal tuberculosis. On CE, three parameters, ≥10 ulcers, >3 involved segments and aphthous ulcers, were more common in patients with CD than in those intestinal tuberculosis. Cobblestoning was observed in five patients with CD and in none with intestinal tuberculosis. The authors hypothesized that a diagnosis of small bowel CD could be made when the number of parameters in CD patients was higher than that for intestinal tuberculosis. The authors calculated that the diagnosis of either CD or intestinal tuberculosis would have been made in 34 of the 35 patients (97%). CONCLUSION: The number of ulcers and involved segments, and the presence of aphthous ulcers, were significantly higher and more common, respectively, in patients with CD than in those with intestinal tuberculosis. Cobblestoning in the small bowel may highly favor a diagnosis of CD on CE.

Silicone optical elements for cost-effective freeform solar concentration.

The use of silicone optical elements is demonstrated for a concentrated photovoltaic system. These components show over 96% transmission through most of the solar spectrum and excellent temperature stability. Unique moldability enables the use of complex freeform designs. A light, compact, and cost-effective concentrated photovoltaic system based on silicone optics is proposed. In this system, air-plasma treatment is utilized to overcome the mechanical properties of silicone and difficulties with coating to reduce Fresnel loss. Lens arrays and waveguides are fabricated by injection molding following freeform optical design by LightTools. First-order characterizations are also performed.

Quasi-phase-matched third harmonic generation in organic multilayers.

We report the first realization of quasi-phase-matched (QPM) third harmonic generation in isotropic polymer films. Spin-coated thin films of ethyl-violet molecules dispersed in a polymer host (EV) were used as cubic nonlinear optical media because of their transparency at both the fundamental (1230 nm) and the third harmonic (410 nm) wavelengths. A passive layer of a UV-curable material was formed to compensate the phase shift between the two light waves after propagating through each EV layer. We fabricated a series of samples with 1~4 EV layers (0~3 alternatingly coated passive layers). The third harmonic output power showed a quadratic increase with the number of layers, providing a strong evidence for successful quasi-phase-matching. A conversion efficiency of 0.15% was observed with a 190 fs pulse input.

Clinical outcomes of colorectal endoscopic submucosal dissection and risk factors associated with piecemeal resection.

BACKGROUND/AIMS: We aimed to investigate the factors associated with piecemeal resection of colorectal neoplasia (CRN), in spite of endoscopic submucosal dissection (ESD). MATERIALS AND METHODS: We analyzed the retrospective data for colorectal ESD cases from January 2005 to April 2014. We also reviewed the piecemeal endoscopic mucosal resection (EMR) for CRNs ≥20 mm, performed over the same period. RESULTS: En bloc resection was possible in 648 (85.7%) of 756 lesions in 740 patients. Multivariate analysis showed that hybrid ESD (odds ratio (OR), 29.07; 95% confidence interval (CI), 15.46-54.65; p<0.01) and mild or severe submucosal fibrosis (OR, 3.62; 95% CI, 1.94-6.76; p<0.01) were independently associated with piecemeal ESD. The en bloc ESD group showed higher histologic complete resection rate than the piecemeal ESD group (80.4% vs. 56.5%; p<0.01), and the piecemeal ESD group showed higher recurrence rate than in the en bloc ESD group (5.6% [4/72] vs. 0.7% [3/450]; p<0.01). Overall recurrence rate was 1.3% (7/522). CONCLUSION: Hybrid ESD and submucosal fibrosis are independently associated with piecemeal ESD. Piecemeal ESD cases recurred more frequently than en bloc ESD cases.

Risankizumab in patients with moderate to severe Crohn's disease: an open-label extension study.

BACKGROUND: Risankizumab, an anti-interleukin 23 antibody, was superior to placebo in achieving clinical and endoscopic remission at week 12 in a randomised, phase 2 induction study in patients with moderately to severely active Crohn's disease. Here we aimed to assess the efficacy and safety of extended intravenous induction and subcutaneous maintenance therapy with risankizumab. METHODS: All patients who completed the 12-week induction phase of the double-blind phase 2 induction study were included in this open-label extension study. Patients who did not achieve deep remission, defined as clinical remission (Crohn's Disease Activity Index [CDAI] <150) and endoscopic remission (Crohn's Disease Endoscopic Index of Severity [CDEIS] ≤4, or ≤2 for patients with isolated ileitis), at week 12 received open-label intravenous therapy with 600 mg risankizumab every 4 weeks for 12 weeks; patients in deep remission at week 12 entered a 12-week washout phase. Patients in clinical remission at week 26 were invited to participate in the maintenance phase of the study, in which they received open-label subcutaneous risankizumab (180 mg) every 8 weeks for 26 weeks. 26-week efficacy endpoints were the proportion of patients in clinical remission (CDAI <150), and the proportion of patients who achieved clinical response (either CDAI of <150 or a reduction from baseline of at least 100 points). 52-week efficacy endpoints were the proportion of patients achieving: clinical remission; clinical response; endoscopic response (>50% CDEIS reduction from baseline); endoscopic remission, as defined previously; mucosal healing; and deep remission. Safety was assessed in patients who received at least one dose of the study drug during the open-label phases of the study. This study is registered with ClinicalTrials.gov, number NCT02031276. FINDINGS: Of the 108 patients who completed the 12-week double-blind induction trial, six patients were in deep remission and entered the 12-week washout phase. 102 patients were not in deep remission, 101 of whom received 12 weeks of 600 mg risankizumab (33 from the original placebo group, 34 from the 200 mg risankizumab group, and 34 from the 600 mg risankizumab group); the other patient declined to continue the study. At week 26, 54 (53%) of 101 patients treated with 600 mg rizankizumab were in clinical remission. Among patients included in the open-label extension trial, clinical remission rates at week 26 versus week 12 were: 18 (55%) versus six (18%) of 33 patients in the original placebo group; 20 (59%) versus seven (21%) of 34 patients in the original 200 mg risankizumab group; and 16 (47%) versus nine (26%) of 34 patients in the original 600 mg risankizumab group. 62 patients received risankizumab maintenance treatment, including the 54 patients who achieved clinical remission at week 26, the six patients who had achieved deep remission at week 12, and one patient because of a protocol violation. At week 52, clinical remission was maintained in 44 (71%) patients; 50 (81%) patients had a clinical response, 22 (35%) patients were in endoscopic remission, and 34 (55%) patients had an endoscopic response. 15 (24%) patients had mucosal healing and 18 (29%) patients achieved deep remission at week 52. Risankizumab was well tolerated with no new safety signals noted. The most frequent treatment-emergent adverse events were arthralgia (25 [22%] of 115 patients), headache (23 [20%]), abdominal pain (21 [18%]), nasopharyngitis (18 [16%]), nausea (18 [16%]), and pyrexia (15 [13%]). Most adverse events were mild or moderate and considered to be unrelated to study treatment. There were no treatment-related deaths. INTERPRETATION: Extended induction treatment with open-label intravenous risankizumab was effective in increasing clinical response and remission rates at week 26. Open-label subcutaneous risankizumab maintained remission until week 52 in most patients who were in clinical remission at week 26. Selective blockade of interleukin 23 warrants further investigation as a treatment for Crohn's disease. FUNDING: Boehringer Ingelheim.

Comparison of Concomitant Mesalamine and Immunomodulator Therapy and Immunomodulator Monotherapy for Crohn's Disease.

BACKGROUND: Although immunomodulators are increasingly used in Crohn's disease (CD), a significant number of gastroenterologists still use 5-aminosalicylate (5-ASA) in combination with azathioprine (AZA) or 6-mercaptopurine (6-MP); there is limited evidence regarding the benefit of concomitant 5-ASA with AZA/6-MP compared with AZA/6-MP monotherapy for the treatment of CD. STUDY DESIGN: A total of 106 patients who received AZA/6-MP for more than 3 months between January 1991 and May 2014 were identified retrospectively. Each patient was matched with 3 randomly selected controls who were treated with concomitant therapy during the same period. RESULTS: The cumulative probabilities of steroid use at 5 and 10 years were 24.9% and 75.8% in the 5-ASA + AZA/6-MP group and 31.2% and 87.8% in the AZA/6-MP group, respectively (P = 0.187). The cumulative probabilities of anti-TNF use, resectional surgery, and disease-related hospitalization were comparable between the groups. The younger age and the use of lower doses of immunomodulators were associated with higher requirement of rescue therapy. CONCLUSIONS: This study did not demonstrate that the concomitant use of 5-ASA with AZA/6-MP showed the proof or effect in terms of steroid requirements, anti-TNF use, resectional surgery, or disease-related hospitalization compared with that of AZA/6-MP alone.

Prevalence of Fructose Malabsorption in Patients With Irritable Bowel Syndrome After Excluding Small Intestinal Bacterial Overgrowth.

BACKGROUND/AIMS: Fructose malabsorption (FM) mimics symptoms of irritable bowel syndrome (IBS), and its prevalence has increased. Diagnosing FM in IBS is challenging because of its overlap with small intestinal bacterial overgrowth (SIBO). We assessed the prevalence of FM by comparing patients with IBS with asymptomatic control individuals after excluding SIBO using the glucose hydrogen breath test (HBT). METHODS: Patients diagnosed with IBS and asymptomatic control individuals were enrolled prospectively. Dietary habits were assessed with the Food Frequency Questionnaire. After excluding SIBO, participants underwent HBTs with both 15 g and 25 g of fructose. RESULTS: Thirty-five patients with IBS and 35 age- and sex-matched asymptomatic control individuals were enrolled. The 15-g fructose HBT yielded positive results in 7 of the 35 (20.0%) patients with IBS and in 2 of 35 (5.7%) controls (P = 0.070). The 25-g fructose HBT was positive in 16 of the 35 (45.7%) patients with IBS and in 8 of the 35 (22.9%) controls (P = 0.040). Analysis of the Food Frequency Questionnaire responses showed no significant differences between the 2 groups in dietary intake, although patients with IBS showed a significantly higher mean fiber intake than controls (21.24 ± 11.35 g vs 15.87 ± 7.07 g, respectively, P = 0.040). CONCLUSIONS: The 25-g fructose HBT identified FM in a significantly higher percentage of SIBO-negative patients with IBS than in asymptomatic control individuals, suggesting that FM may correlate with IBS. Education regarding dietary control of foods containing fructose may be useful for the management of patients with IBS.

Presence of Fe-Al binary oxide adsorbent cake layer in ceramic membrane filtration and their impact for removal of HA and BSA.

To enhance the removal of natural organic matter (NOM) in ceramic (Ce) membrane filtration, an iron-aluminum binary oxide (FAO) was applied to the ceramic membrane surface as the adsorbent cake layer, and it was compared with heated aluminum oxide (HAO) for the evaluation of the control of NOM. Both the HAO and FAO adsorbent cake layers efficiently removed the NOM regardless of NOM's hydrophobic/hydrophilic characteristics, and the dissolved organic carbon (DOC) removal in NOM for FAO was 1-1.12 times greater than that for HAO, which means FAO was more efficient in the removal of DOC in NOM. FAO (0.03 µm), which is smaller in size than HAO (0.4 µm), had greater flux reduction than HAO. The flux reduction increased as the filtration proceeded because most of the organic foulants (colloid/particles and soluble NOM) were captured by the adsorbent cake layer, which caused fouling between the membrane surface and the adsorbent cake layer. However, no chemically irreversible fouling was observed on the Ce membrane at the end of the FAO adsorbent cake layer filtration. This means that a stable adsorbent cake layer by FAO formed on the Ce membrane, and that the reduced pure water flux of the Ce membrane, resulting from the NOM fouling, can easily be recovered through physicochemical cleaning.

Clinical characteristics and long-term prognosis of elderly onset ulcerative colitis.

BACKGROUND AND AIM: The aim of this study was to investigate the clinical characteristics and prognosis of patients with elderly onset ulcerative colitis (EOUC), a new growing subgroup of UC. METHODS: This study retrospectively analyzed 3060 South Korean UC patients diagnosed between 1977 and 2014. The clinical characteristics and prognosis of EOUC, defined as UC in those aged ≥ 60 years at diagnosis, were compared with those of non-EOUC (NEOUC). RESULTS: Among the 3060 patients, 226 were diagnosed with EOUC (7.4%, median age at diagnosis 65.9 years [interquartile range, 62.9-68.7 years], 58.4% male). The frequency of EOUC increased from 3.9% in the interval 1977-1999 to 9.7% in the interval 2008-2014 (P < 0.001). There were more ex-smokers in the EOUC than in the NEOUC group (44.2% vs 19.9%, P < 0.001). In the EOUC group, extensive colitis at diagnosis, and the maximum extent thereof, was less than in the NEOUC group (13.7% vs 22.6%, P = 0.002, and 34.5% vs 42.5%, P = 0.011, respectively). The 10-year cumulative colectomy rate was significantly higher in the EOUC than in the NEOUC group (12.6% vs 7.7%, P = 0.015). UC-related and all-cause mortality were higher in the EOUC than in the NEOUC group (3.5% vs 0.6%, P < 0.001, and 12.4% vs 1.8%, P < 0.001, respectively). CONCLUSION: Elderly onset ulcerative colitis patients are likely to exhibit distinct features both at diagnosis and during follow-up. It is necessary to pay more attention to, and to conduct further studies on, this particular group of patients.

Assessment of factors associated with smoking cessation at diagnosis or during follow-up of Crohn's disease.

BACKGROUND AND AIM: Smoking cessation is known to improve the course of Crohn's disease (CD). However, the factors associated with smoking cessation after CD diagnosis have not been well established. METHODS: Clinical characteristics and change in smoking status were evaluated in 445 current smokers at the time of CD diagnosis. Patients were classified into three subgroups based on their final smoking status and time of smoking cessation: non-quitters, quitters at diagnosis, and quitters during follow-up. RESULTS: The overall smoking cessation rate was 55.7% (248 of 445 patients). The diagnosis of CD was the main reason for quitting (41.5%, 103 of 248 patients). Smoking cessation at the time of CD diagnosis was associated with intestinal resection within 3 months from CD diagnosis (odds ratio [OR] 2.355, 95% confidence interval [CI] 1.348-4.116, P = 0.003), light smoking (OR 2.041, 95% CI 1.157-3.602, P = 0.014), and initiation of smoking before 18 years of age (OR 0.570, 95% CI 0.327-0.994, P = 0.047). Light smoking (OR 1.762, 95% CI 1.019-3.144, P = 0.043) and initiation of smoking before 18 years (OR 0.588, 95% CI 0.381-0.908, P = 0.017) were also associated with overall smoking cessation. CONCLUSION: Quitters after CD diagnosis, including quitters at diagnosis and quitters during follow-up, had features distinct from those of non-quitters. Given the motivation at CD diagnosis, a detailed history of smoking habits should be taken and all current smokers should be encouraged to quit smoking at the time of CD diagnosis.

Local recurrence and subsequent endoscopic treatment after endoscopic piecemeal mucosal resection with or without precutting in the colorectum.

BACKGROUND/AIMS: Precutting before endoscopic piecemeal mucosal resection (EPMR) may increase colorectal polyp resection effectiveness. We aimed to identify risk factors for recurrence after conventional EPMR (CEPMR) and precut EPMR (PEPMR) and investigated endoscopic treatment outcomes for recurrent cases. METHODS: The medical records of patients with colorectal polyps treated by EPMR were analyzed. Patients without follow-up surveillance colonoscopies were excluded. RESULTS: Among 359 lesions, the local recurrence rate on the first surveillance colonoscopy was 5.8% (18/312) and 6.4% (3/47) after CEPMR and PEPMR, respectively. Among lesions without recurrence at the first surveillance colonoscopy, the rates of late recurrence on subsequent surveillance colonoscopy were 3.9% (6/152) and 0% after CEPMR and PEPMR, respectively. Larger tumor size was the only independent risk factor for recurrence (odds ratio, 7.93; 95% confidence interval, 1.95-32.30; P<0.001). Endoscopic treatment was performed for all 27 recurrences. A combination of ≥2 endoscopic treatment modalities was used in 19 of 27 recurrences (70.4%). Surveillance colonoscopies were performed in 20 of 27 recurrences after endoscopic treatment. One (5.0%) had a re-recurrence and was treated by surgical resection because recurrence occurred at the appendiceal orifice. Nineteen of 20 lesions (95.0%) could be cured endoscopically, although 3 of the 19 showed second or third recurrences and were treated by repeat endoscopic resection. CONCLUSIONS: The local recurrence rates after CEPMR and PEPMR were similar. Larger tumor size was an independent risk factor for local recurrence after EPMR. Endoscopic treatment of recurrences resulted in high cure rates, although combination methods were necessary in many cases.

Temporal trends in the misdiagnosis rates between Crohn's disease and intestinal tuberculosis.

AIM: To investigate the temporal trends in the misdiagnosis rate between Crohn's disease (CD) and intestinal tuberculosis (ITB) in South Korea. METHODS: We retrospectively reviewed the medical records of patients managed for CD or ITB at Asan Medical Center, a tertiary referral hospital, Seoul, Korea between 1996 and 2014. The temporal trends in the misdiagnosis rates between the two diseases were analyzed. The demographic and clinical characteristics were compared between CD patients who were initially misdiagnosed as ITB (final CD group) and vice versa (final ITB group). Final diagnostic criteria for ITB and medication for CD before definite diagnosis of TB were also analyzed in final ITB group. RESULTS: In total, 2760 patients were managed for CD and 772 patients for ITB between 1996 and 2014. As well, 494 of the 2760 CD patients (17.9%) were initially misdiagnosed as ITB and 83 of the 772 ITB patients (10.8%) as CD. The temporal trend in misdiagnosing CD as ITB showed a decrease (OR = 0.89, 95%CI: 0.87-0.91, P < 0.001), whereas the temporal trend in misdiagnosing ITB as CD showed an increase (OR = 1.06, 95%CI: 1.01-1.11, P = 0.013). Age at diagnosis, presenting symptoms, and proportion of patients with active/past perianal fistula and active/inactive pulmonary tuberculosis (TB) were significantly different between final CD group and final ITB group. Forty patients (48.2%) in final ITB group were diagnosed by favorable response to empirical anti-TB treatment. Seventeen patients (20.5%) in final ITB group had inappropriately received corticosteroids and/or thiopurines due to misdiagnosis as CD. However, there were no mortalities in both groups. CONCLUSION: Cases of CD misdiagnosed as ITB have been decreasing, whereas cases of ITB misdiagnosed as CD have been increasing over the past two decades.

Athermal silicon optical add-drop multiplexers based on thermo-optic coefficient tuning of sol-gel material.

Silicon photonics has gained interest for its potential to provide higher efficiency, bandwidth and reduced power consumption compared to electrical interconnects in datacenters and high performance computing environments. However, it is well known that silicon photonic devices suffer from temperature fluctuations due to silicon's high thermo-optic coefficient and therefore, temperature control in many applications is required. Here we present an athermal optical add-drop multiplexer fabricated from ring resonators. We used a sol-gel inorganic-organic hybrid material as an alternative to previously used materials such as polymers and titanium dioxide. In this work we studied the thermal curing parameters of the sol-gel and their effect on thermal wavelength shift of the rings. With this method, we were able to demonstrate a thermal shift down to -6.8 pm/°C for transverse electric (TE) polarization in ring resonators with waveguide widths of 325 nm when the sol-gel was cured at 130°C for 10.5 hours. We also achieved thermal shifts below 1 pm/°C for transverse magnetic (TM) polarization in the C band under different curing conditions. Curing time compared to curing temperature shows to be the most important factor to control sol-gel's thermo-optic value in order to obtain an athermal device in a wide temperature range.