Effects of heteroatom substitution in conjugated heterocyclic compounds on photovoltaic performance: from sulfur to tellurium

Band gaps of benzochalcogenophene-based organic semiconductors and the efficiencies of the corresponding photovoltaic devices can be tuned through heteroatom variation.

Gadoxetic acid-enhanced MRI for T-staging of gallbladder carcinoma: emphasis on liver invasion

OBJECTIVE

To evaluate the diagnostic performance of gadoxetic acid-enhanced MRI with an emphasis on the usefulness of the hepatobiliary phase (HBP) in T-staging of gallbladder carcinoma.

METHODS

66 patients with surgically confirmed gallbladder carcinoma underwent MRI. Two radiologists independently reviewed two sets of gadoxetic acid-enhanced MRI without and with the HBP. Local tumour spread was evaluated according to T-staging, and the results were compared with pathological findings. The diagnostic performance of two image sets to differentiate each T-stage was compared.

RESULTS

The sensitivities of MRI with the HBP to differentiate T1 vs ≥ T2 lesions, ≤ T2 vs ≥ T3 lesions and ≤ T3 vs T4 lesions were 96.3%, 85.7% and 100% for Observer 1 and 92.6%, 95.2% and 100% for Observer 2, respectively (p<0.0001). By adding the HBP, the sensitivities to differentiate ≤ T2 vs ≥ T3 lesions were increased from 66.7% to 85.7% for Observer 1 and from 81.0% to 95.2% for Observer 2, although there was no significant difference (p>0.05). The overall accuracies for T-staging were increased from 80.3% to 86.4% for Observer 1, a statistically significant degree (p=0.046), and from 83.8% to 87.9% for Observer 2 (p>0.05). The k-value for the two observers indicated excellent agreement.

CONCLUSION

Gadoxetic acid-enhanced MRI provided acceptable diagnostic performance for T-staging of gallbladder carcinoma. Addition of the HBP aids in the detection of liver invasion.

ADVANCES IN KNOWLEDGE

In the T-staging of gallbladder carcinoma, gadoxetic acid-enhanced MRI with the HBP may enhance detection of liver invasion.

First-line radiofrequency ablation with or without artificial ascites for hepatocellular carcinomas in a subcapsular location: local control rate and risk of peritoneal seeding at long-term follow-up

AIM

To compare the long-term local control of hepatocellular carcinoma (HCC) and risk of peritoneal seeding via percutaneous radiofrequency ablation (RFA) using artificial ascites with those of RFA without artificial ascites.

MATERIALS AND METHODS

The Institutional Review Board approved this retrospective study. From April 2005 to February 2008, 160 patients (121 men, 39 women; age range 36-79 years) with a single subcapsular HCC (mean size 2.19 cm) were treated with ultrasonography-guided percutaneous RFA as a first-line therapy. Forty-four patients were treated with RFA using artificial ascites, whereas the other 116 patients were treated without artificial ascites. The cumulative local tumour progression (LTP) and peritoneal seeding were compared in both groups using follow-up computed tomography (CT). Cumulative LTP rates were analysed using the Kaplan-Meier method and the log-rank test. Risk of peritoneal seeding was investigated by means of multivariate analysis.

RESULTS

The overall median follow-up period was 52.5 months (range 13-76 months). The 1, 2, 4, and 6 year cumulative LTP rates were 17.1, 27.6, 35.2, and 35.2%, respectively, in the group with artificial ascites, and 8, 15.2, 26.6, and 34.4% in the group without artificial ascites, without significant difference (p = 0.332). The rates of peritoneal seeding were 6.8% (3/44) in the group with artificial ascites and 2.6% (3/116) in the group without artificial ascites, a non-significant difference (p = 0.347). The biopsy prior to RFA was the independent risk factor of peritoneal seeding regardless of the use of artificial ascites.

CONCLUSION

Long-term local tumour control and risk of peritoneal seeding were comparable for RFA with or without artificial ascites when used as a first-line therapy for subcapsular HCC.

Structure Development in Melt Spinning Syndiotactic Polypropylene and Comparison to Isotactic Polypropylene

A basic investigation of the development of crystallization and orientation during the melt spinning of syndiotactic and isotactic polypropylene is described. Both polymers were melt spun through ambient air or into ice water at various draw-down ratios and melt temperatures. The melt spun filaments were characterized by wide angle x-ray diffraction (WAXD), birefringence and differential scanning calorimetry (DSC). The polymorphic behavior of isotactic polypropylene during melt spinning is well known. The filaments melt spun through ambient air exhibit the monoclinic α-form while the filaments melt spun into ice water form a smectic structure at low draw-down ratios. Syndiotactic polypropylene also exhibited polymorphic behavior during melt spinning. Disordered Form I with (t2g2)2 helices was found at low spinline stresses and Form III with all trans chain conformation was found at high spinline stresses. The criterion of the spinline stress for this transition was found to be about 6–9 MPa for all samples of various molecular weights, melt temperatures and cooling rates. Syndiotactic polypropylene crystallized much more slowly than isotactic polypropylene and did not exhibit a smectic mesomorphism under ice-water quenched conditions. The melt spun filaments of syndiotactic polypropylene exhibited lower birefringences and amorphous orientations but higher crystalline orientations than those of isotactic polypropylene, compared at the same spinline stresses.

Crystallization and Orientation Development in Melt Spinning Isotactic PP of Varying Tacticity

We investigated the effects of tacticity on crystallization and orientation development in melt spinning isotactic polypropylene (iPP) through air. Melt-spun fibers were characterized by wide-angle X-ray diffraction (WAXD), birefringence and differential scanning calorimetry (DSC). The melt-spun fibers usually exhibited the monoclinic α-crystalline form, but the mesomorphic form was found under certain processing conditions. The mesomorphic structure was formed more readily in low tacticity fibers. We found certain amounts of hexagonal β-crystalline form in all of the α-form fiber samples. The amouns were generally negligibly small, but the low tacticity fibers spun at high draw-down ratios exhibited significant amounts of β-form crystals. At low spinline stress levels, some low tacticity fibers exhibited lower birefringence and chain orientation than high tacticity fibers due to a less perfect crystal structure. At certain high spinline stress levels, low tacticity fibers exhibited much higher birefringence and chain-axis orientation levels than expected. This was attributed to a reduction in epitaxial lamellar branching (a*-axis oriented group in bimodal orientation). However, the extent of lamellar branching in low tacticity fibers appeared to increase again at higher stress levels. This led to a significant decrease in birefringence and crystalline orientation.

Differentiating xanthogranulomatous cholecystitis from wall-thickening type of gallbladder cancer: added value of diffusion-weighted MRI

AIM

To evaluate the benefit of diffusion-weighted imaging (DWI) in differentiating xanthogranulomatous cholecystitis from the wall-thickening type of gallbladder cancer.

MATERIALS AND METHODS

This retrospective study was approved by the institutional review board. Fourteen patients with xanthogranulomatous cholecystitis and 19 patients with the wall-thickening type of gallbladder cancer were included. Qualitative (visual diffusion restriction compared to liver parenchyma) and quantitative [apparent diffusion coefficient (ADC)] analyses were performed. Conventional MRI findings including dynamic enhancement pattern between the two groups were also analysed. Two observers independently reviewed conventional magnetic resonance imaging (MRI) images and subsequently reviewed combined conventional MRI and DWI images. Pairwise comparison of the receiver operating characteristic (ROC) curves was used to compare diagnostic performances.

RESULTS

In conventional MRI findings, xanthogranulomatous cholecystitis showed significant continuity of enhancing mucosal line [79% (11/14) versus 26% (5/19), p = 0.003] and intramural T2-high signal intensity [64% (9/14) versus 21% (4/19), p = 0.012] compared to the wall-thickening type of gallbladder cancer. The enhancement pattern of gallbladder cancer compared to liver parenchyma showed earlier onset than that of xanthogranulomatous cholecystitis (p = 0.001). Diffusion restriction was more frequently seen in the wall-thickening type of gallbladder cancer (68%, 13/19) than in xanthogranulomatous cholecystitis (7%, 1/14; p < 0.001). The mean ADC value of xanthogranulomatous cholecystitis was higher than that of the wall-thickening type of gallbladder cancer with statistical significance (1.637 × 10(-3) mm(2)/s versus 1.076 × 10(-3) mm(2)/s, p = 0.005). Diagnostic performance [area under ROC curve (Az)] of both observers improved significantly after additional review of DWI; Az improved from 0.737 to 0.930 (p = 0.027) for observer 1 and from 0.675 to 0.938 (p = 0.008) for observer 2.

CONCLUSION

Addition of DWI to conventional MRI improves discrimination between xanthogranulomatous cholecystitis and the wall-thickening type of gallbladder cancer.

Low loss coupling to sub-micron thick rib and nanowire waveguides by vertical tapering

Highly nonlinear planar glass waveguides have been shown to be useful for all optical signal processing. However, the typical SMF-28 fiber to waveguide coupling loss of ~5dB/end remains a barrier to practical implementation. Low loss coupling to a fiber using vertical tapering of the waveguide film is analyzed for rib and nanowire waveguides and experimentally demonstrated for ribs showing polarization and wavelength independence over >300nm bandwidth. Tapers with essentially zero excess loss led to total losses from the waveguide to fiber core of 1.1dB per facet comprising only material absorption (0.75dB) and mode overlap loss (0.36dB), both of which can be eliminated with improvements to processing and materials.

The effect of oral prostaglandin analogue on painful diabetic neuropathy: a double-blind, randomized, controlled trial

This study was performed to assess the efficacy of beraprost sodium (BPS) in painful diabetic peripheral neuropathy (DPN) in type 2 diabetes mellitus (T2DM) patients. In this randomized clinical trial, 99 T2DM patients (41% male, age 60 ± 6 years) with DPN but without evidence of peripheral artery disease were randomized to receive either BPS (40 µg, tid) or placebo for 8 weeks. The primary end point was the improvement of the total symptom score (TSS), temperature rebound (TR) and nadir to peak (NP) above baseline. After 8 weeks treatment, the change of TSS in the BPS group showed a significant improvement compared to the placebo group (2.80 ± 2.48 vs. 1.60 ± 1.94 points, p = 0.009). Furthermore, the number of patients who showed signs of improvement in TSS and the proportion of patients with 50% relief of symptom was also significantly greater in the BPS group than in the placebo group (83.7 vs. 62%, p = 0.015, 36.2 vs. 14%, p = 0.009, respectively). In conclusion, treatment with BPS significantly improved TSS over an 8-week period.

Anterior deltoid deficiency in reverse total shoulder replacement

Reverse total shoulder replacement (RTSR) depends on adequate deltoid function for a successful outcome. However, the anterior deltoid and/or axillary nerve may be damaged due to prior procedures or injury. The purpose of this study was to determine the compensatory muscle forces required for scapular plane elevation following RTSR when the anterior deltoid is deficient. The soft tissues were removed from six cadaver shoulders, except for tendon attachments. After implantation of the RTSR, the shoulders were mounted on a custom-made shoulder simulator to determine the mean force in each muscle required to achieve 30° and 60° of scapular plane elevation. Two conditions were tested: 1) Control with an absent supraspinatus and infraspinatus; and 2) Control with anterior deltoid deficiency. Anterior deltoid deficiency resulted in a mean increase of 195% in subscapularis force at 30° when compared with the control (p = 0.02). At 60°, the subscapularis force increased a mean of 82% (p < 0.001) and the middle deltoid force increased a mean of 26% (p = 0.04).

Scapular plane elevation may still be possible following an RTSR in the setting of anterior deltoid deficiency. When the anterior deltoid is deficient, there is a compensatory increase in the force required by the subscapularis and middle deltoid. Attempts to preserve the subscapularis, if present, might maximise post-operative function.