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Purpose Colonoscopy is an effective method of screening for colorectal cancer (CRC), and it can prevent CRC by detection and removal of precancerous lesions. The most important considerations when performing colonoscopy screening are the safety and satisfaction of the patient and the diagnostic accuracy. Accordingly, the Korean Society of Coloproctology (KSCP) herein proposes an optimal level of standard performance to be used in endoscopy units and by individual colonoscopists for screening colonoscopy. These guidelines establish specific criteria for assessment of safety and quality in screening colonoscopy. Methods The Colonoscopy Committee of the KSCP commissioned this Position Statement. Expert gastrointestinal surgeons representing the KSCP reviewed the published evidence to identify acceptable quality indicators and indicators that lacked sufficient evidence. Results The KSCP recommends an optimal standard list for quality control of screening colonoscopy in the following 6 categories: training and competency of the colonoscopist, procedural quality, facilities and equipment, performance indicators and auditable outcomes, disinfection of equipment, and sedation and recovery of the patient. Conclusion The KSCP recommends that endoscopy units performing CRC screening evaluate 6 key performance measures during daily practice.

A new polymeric semiconductor, which can effectively extend linear dynamic ranges (LDRs) of organic photodiodes (OPDs), was developed. Copolymers based on alkylthio-substituted benzo[1,2-b:4,5-b′]d...

Charge-transport materials for use in highly efficient and stable perovskite solar cells (PSCs) must exhibit energy levels appropriate for high charge selectivity, sufficiently high charge-transport ability for efficient charge collection, and high humidity resistance for long-term device stability. Polythiophenes are a promising class of hole-transport layer (HTL) materials that could satisfy these requirements. However, PSCs fabricated using conventional poly(3-hexylthiophene) (P3HT) HTLs show limited efficiencies of

Organic solar cells based on bulk heterojunctions (BHJs) are attractive energy-conversion devices that can generate electricity from absorbed sunlight by dissociating excitons and collecting charge carriers. Recent breakthroughs attained by development of nonfullerene acceptors result in significant enhancement in power conversion efficiency (PCEs) exceeding 17%. However, most of researches have focused on pursuing high efficiency of small-area (

The control of the optoelectronic properties of the interlayers of perovskite solar cells (PSCs) is crucial for achieving high photovoltaic performances. Of the solution-processable interlayer candidates, NiOx is considered one of the best inorganic hole-transporting layer (HTL) materials. However, the power conversion efficiencies (PCEs) of NiOx-based PSCs are limited by the unfavorable contact between perovskite layers and NiOx HTLs, the high density of surface trap sites, and the inefficient charge extraction from perovskite photoactive layers to anodes. Here, we introduce a new organic-inorganic double HTL consisting of a Cu:NiOx thin film passivated by a conjugated polyelectrolyte (PhNa-1T) film. This double HTL has a significantly lower pinhole density and forms better contact with perovskite films, which results in enhanced charge extraction. As a result, the PCEs of PSCs fabricated with the double HTL are impressively improved up to 17.0%, which is more than 25% higher than that of the corresponding PSC with a Cu:NiOx HTL. Moreover, PSCs with the double HTLs exhibit similar stabilities under ambient conditions to devices using inorganic Cu:NiOx. Therefore, this organic-inorganic double HTL is a promising interlayer material for high performance PSCs with high air stability.

Tandem solar cells which are electrically connected with various photoactive materials have the potential to solve the current challenges by exceeding the theoretically limited efficiency of single junction solar cells. Here the first monolithic organic/silicon tandem cell is reported based on a semitransparent polymer on a crystalline silicon (c-Si) substrate. Herein, experimental results are presented for four-terminal (4-T) and monolithic two-terminal (2-T) organic/c-Si tandem cells using organic cells with an inverted n-i-p structure and c-Si cells with an n-type TOPCon structure with detailed analysis. The best 4-T tandem cell efficiency is 15.22%, and 2-T results show that the top (organic) and bottom (c-Si) cells are electrically connected by an open-circuit voltage over 1.4 V. Further, a simulated efficiency of over 20% using the organic/c-Si tandem is achieved, implying the tandem efficiency can be enhanced through further improvement of electric and optical characteristics with the optimization.

Stretchability and areal coverage of active devices are critical design considerations of stretchable or wearable photovoltaics and photodetections where high areal coverages are required. However, simultaneously maximizing both properties in conventional island-bridge structures through traditional two-dimensional manufacturing processes is difficult due to their inherent trade-offs. Here, a 3D printer-based strategy to achieve extreme system stretchability and high areal coverage through combining fused deposition modeling (FDM) and flexible conductive nanocomposites is reported. Distinguished from typical approaches of using conductive filaments for FDM which have a flexibility dilemma and conductivity trade-offs, the proposed axiomatic approach to embed a two-dimensional silver nanowire percolation network into the surfaces of flexible 3D printed structures offers sufficient conductivity and deformability as well as additional benefits of electrical junction enhancement and encapsulation of silver nanowires. Kirigami/origami-pattern-guided three-dimensional arrangements of encapsulated interconnections provide efficient control over stretchability and areal coverage. The suggested process enables a perovskite solar module with an initial areal coverage of ∼97% to be electrically and mechanically reversible with 400% system stretchability and 25 000% interconnect stretchability under the 1000 cycle test, by folding down or hiding the origami-applied interconnects under the islands. This 3D printing strategy of potentially low cost, large size capabilities, and high speed is promising for highly flexible future energy conversion applications.

We synthesized a planar pDPPTTi-OD polymer based on diketopyrrolopyrrole (DPP) and thieno [2,3- b ]thiophene (TTi) and investigated the electrical properties of the pDPPTTi-OD polymer. pDPPTTi-OD films displayed a low optical bandgap of 1.57 eV, and HOMO and LUMO levels of −5.40 and −3.74 eV, respectively. The 150°C-annealed pDPPTTi-OD films showed a high hole mobility of 0.16 cm 2 V −1 s −1 in organic thin-film transistor (OTFT) devices. The photovoltaic properties of polymer solar cells (PSCs) incorporating the pDPPTTi-OD were also measured. A pDPPTTi-OD:PC 71 BM blend film was spin-coated at 25, 70 and 90 °C. High-temperature processing significantly improved the power conversion efficiency of PSCs by effectively reducing the PC 71 BM domain sizes, which improved the miscibility between pDPPTTi-OD and PC 71 BM. This work demonstrated that the TTi moiety is a useful donor building block for high- performance D–A type polymers in OTFTs and PSCs, and that processing temperatures should be controlled to fully realize the materials' beneficial intrinsic properties.

Lead halide perovskite solar cells (PSCs) are thought to be promising energy power suppliers because of their feasibility for high power conversion efficiency (PCE), light weight, and flexible architecture. The preparation of charge transporting layers at low temperature has been essential for high-performance and flexible PSCs. Recently, low-temperature-processed metal oxides have been a desirable material for charge transport and air stability for PSCs, instead of organic semiconductors. However, pristine metal oxides fabricated at low temperature have still precluded high performance of the device because of their low conductivity and large deviation in energy levels from the conduction band or valance band of the perovskite. Therefore, doping metals in the metal oxides has been considered as an effective method to endow suitable electrical properties. Herein, we developed a highly efficient electron transporting layer (ETL) comprising Li-doped SnO2 (Li:SnO2) prepared at low temperature in solution. The doped Li in SnO2 enhanced conductivity as well as induced a downward shift of the conduction band minimum of SnO2, which facilitated injection and transfer of electrons from the conduction band of the perovskite. The PCE was measured to be 18.2% and 14.78% for the rigid and flexible substrates, respectively. The high-performance and flexible PSCs could be potentially used as a wearable energy power source.

Organo-lead halide perovskite solar cells (PSCs) have received great attention because of their optimized optical and electrical properties for solar cell applications. Recently, a dramatic increase in the photovoltaic performance of PSCs with organic hole transport materials (HTMs) has been reported. However, as of now, future commercialization can be hampered because the stability of PSCs with organic HTM has not been guaranteed for long periods under conventional working conditions, including moist conditions. Furthermore, conventional organic HTMs are normally expensive because material synthesis and purification are complicated. It is herein reported, for the first time, octadecylamine-capped pyrite nanoparticles (ODA-FeS2 NPs) as a bi-functional layer (charge extraction layer and moisture-proof layer) for organo-lead halide PSCs. FeS2 is a promising candidate for the HTM of PSCs because of its high conductivity and suitable energy levels for hole extraction. A bi-functional layer based on ODA-FeS2 NPs shows excellent hole transport ability and moisture-proof performance. Through this approach, the best-performing device with ODA-FeS2 NPs-based bi-functional layer shows a power conversion efficiency of 12.6% and maintains stable photovoltaic performance in 50% relative humidity for 1000 h. As a result, this study has the potential to break through the barriers for the commercialization of PSCs.

For realizing flexible perovskite solar cells (PSCs), it is important to develop low-temperature processable interlayer materials with excellent charge transporting properties. Herein, a novel polymeric hole-transport material based on 1,4-bis(4-sulfonatobutoxy)benzene and thiophene moieties (PhNa-1T) and its application as a hole-transport layer (HTL) material of high-performance inverted-type flexible PSCs are introduced. Compared with the conventionally used poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), the incorporation of PhNa-1T into HTL of the PSC device is demonstrated to be more effective for improving charge extraction from the perovskite absorber to the HTL and suppressing charge recombination in the bulk perovskite and HTL/perovskite interface. As a result, the flexible PSC using PhNa-1T achieves high photovoltaic performances with an impressive power conversion efficiency of 14.7%. This is, to the best of our knowledge, among the highest performances reported to date for inverted-type flexible PSCs. Moreover, the PhNa-1T-based flexible PSC shows much improved stability under an ambient condition than PEDOT:PSS-based PSC. It is believed that PhNa-1T is a promising candidate as an HTL material for high-performance flexible PSCs.

Background Ligation of the intersphincteric fistula tract (LIFT) is a sphincter-preserving operation for anal fistulas. Although it has advantages in preserving continence after surgery, it is difficult to perform owing to the narrow field of view. We performed a modified surgical procedure based on the LIFT to overcome these drawbacks. Materials and methods Twenty-eight patients who were scheduled to undergo high ligation of the anal fistula tract by the lateral approach for the treatment of transsphincteric anal fistulas were prospectively studied. Instead of making a new stab incision on the intersphincteric groove, we dissected along the fistula tract from the external opening until the intersphincteric space appeared. The fistula tract was then ligated close to the internal anal sphincter with absorbable sutures, and the distal part of the ligation was cut off. A cored-out wound was left open for drainage. Results The median follow-up was 16 months (range, 8–27 months). Of the 28 patients, 19 (68%) had simple transsphincteric fistulas and 9 (32%) had complex transsphincteric fistulas. Successful fistula closure was achieved in 21 patients (75%), with a median healing time of 4 weeks (range, 3–7 weeks). None of the patients complained of any incontinence symptoms after the procedure. Of the seven patients (25%) who failed to heal successfully, two (7%) did not heal up to 2 months after surgery and five (18%) experienced recurrence after complete healing. Conclusion High ligation of the anal fistula tract by lateral approach may be a useful sphincter-sparing procedure for transsphincteric anal fistulas.

A series of hole-transporting materials (HTMs) based on [2,2]paracyclophane and triphenyl-amine (TPA) was synthesized. We studied the effect of the chemical structure of the HTM on the photovoltaic performance of perovskite solar cells by varying the number of TPA charge transporting components in the HTM. Tetra-TPA, in which four TPAs are incorporated into the [2,2]paracyclophane core, exhibited better hole transport properties than di-TPA and tri-TPA, which contain two and three TPAs, respectively. In particular, incorporation of the TPA group with a multi-armed structure effectively enhanced the conductivity of the HTM layer in the out-of-plane direction in the solar cell device. Due to the improved charge transport and appropriate molecular energy levels of tetra-TPA, the perovskite solar cell based on the tetra-TPA HTM achieved higher Jsc and FF values than the devices based on di-TPA and tri-TPA HTMs, with a high solar cell efficiency (17.9%).

We prepared a series of small molecules based on 7,7'-(4,4-bis(2-ethylhexyl)-4H-silolo[3,2-b:4,5-b']dithiophene-2,6-diyl)bis(4-(5'-hexyl-[2,2'-bithiophene]-5-yl)benzo[c][1,2,5]thiadiazole) with different fluorine substitution patterns (0F-4F). Depending on symmetricity and numbers of fluorine atoms incorporated in the benzo[c][1,2,5]thiadiazole unit, they show very different optical and morphological properties in a film. 2F and 4F, which featured symmetric and even-numbered fluorine substitution patterns, display improved molecular packing structures and higher crystalline properties in a film compared with 1F and 3F and thus, 2F achieved the highest OTFT mobility, which is followed by 4F. In the bulk heterojunction solar cell fabricated with PC71BM, 2F achieves the highest photovoltaic performance with an 8.14% efficiency and 0F shows the lowest efficiency of 1.28%. Moreover, the planar-type perovskite solar cell (PSC) prepared with 2F as a dopant-free hole transport material shows a high power conversion efficiency of 14.5% due to its high charge transporting properties, which were significantly improved compared with the corresponding PSC device obtained from 0F (8.5%). From the studies, it is demonstrated that low variation in the local dipole moment and the narrow distribution of 2F conformers make intermolecular interactions favorable, which may effectively drive crystal formations in the solid state and thus, higher charge transport properties compared with 1F and 3F.

We report a highly efficient p–i–n type planar perovskite solar cell with a hybrid PEDOT/NiOx hole-extraction layer. It has been found that the perovskite solar cell with a NiOx thin film as a hole-extraction layer generally exhibits lower fill factor compared to the conventionally used PEDOT:PSS thin film, whereas it shows higher photocurrent and photovoltage. The fill factor of the NiOx-based perovskite solar cell can be significantly improved by treating the NiOx surface with a dilute PEDOT solution. The photoluminescence quenching study and impedance spectroscopic (IS) analysis have revealed that the hole injection at the perovskite/NiOx interface is significantly facilitated with the PEDOT treatment, which should lead to the increased fill factor. As a result, the p–i–n type planar perovskite solar cell with the new hybrid hole-extraction layer exhibits a high conversion efficiency of 15.1% without the hysteresis effect.

Noble metal-free mesoscopic perovskite solar cell based on low-cost molybdenum (Mo) cathode has been developed for the first time. By optimizing the thickness of Mo electrode and combination with high quality perovskite layer, the Mo cathode-based perovskite solar cell exhibited a best power conversion efficiency as high as 15.06% with invariance of current density–voltage curves at different scan rates and very small hysteresis according to scan direction. In addition to photovoltaic performances, importance of mechanical durability of a cathode material for perovskite solar cell was highlighted and results from nano-indentation and scratch test indicated that Mo electrode has superior resistance and restoration capability against external scratch or deformation compared to Au electrode. The Mo cathode-based perovskite solar cells have great potential for realizing low cost and high performance as well as mechanical durability.

We synthesized a solution-processable low band gap small molecule, Si1TDPP-EE-COC6, for use as a semiconducting channel material in organic thin film transistors (OTFTs). The Si1TDPP-EE-COC6 is composed of electron-rich thiophene–dithienosilole–thiophene (Si1T) units and electron-deficient diketopyrrolopyrrole (DPP) and carbonyl units. SiTDPP-EE-COC6-based OTFTs with Au source/drain electrodes were fabricated, and their electrical properties were systematically investigated with increasing thermal annealing temperature. The hole and electron mobilities of as-spun Si1TDPP-EE-COC6 were 3.3 × 10–4 and 1.7 × 10–4 cm2 V–1 s–1, respectively. The carrier mobilities increased significantly upon thermal annealing at 150 °C, yielding a hole mobility of 0.003 cm2 V–1 s–1 and an electron mobility of 0.002 cm2 V–1 s–1. The performance enhancement upon thermal annealing was strongly associated with the formation of a layered edge-on structure and a reduction in the π–π intermolecular spacing. Importantly, the use of at...

A highly flexible and transparent conductive electrode based on consecutively stacked layers of conductive polymer (CP) and silver nanowires (AgNWs) fully embedded in a colorless polyimide (cPI) is achieved by utilizing an inverted layer-by-layer processing method. This CP-AgNW composite electrode exhibits a high transparency of >92% at wavelengths of 450–700 nm and a low resistivity of 7.7 Ω ◻−1, while its ultrasmooth surface provides a large contact area for conductive pathways. Furthermore, it demonstrates an unprecedentedly high flexibility and good mechanical durability during both outward and inward bending to a radius of 40 μm. Subsequent application of this composite electrode in organic solar cells achieves power conversion efficiencies as high as 7.42%, which represents a significant improvement over simply embedding AgNWs in cPI. This is attributed to a reduction in bimolecular recombination and an increased charge collection efficiency, resulting in performance comparable to that of indium tin oxide-based devices. More importantly, the high mechanical stability means that only a very slight reduction in efficiency is observed with bending (

High-mobility and low-voltage-operated organic field-effect transistors (OFETs) are demonstrated by the design of a new fluorinated benzothiadiazole-based conjugated polymer with fluorinated high-k polymer dielectrics. A record-breaking high hole mobility of 9.0 cm(2) V(-1) s(-1) for benzothiadiazole-based semiconducting polymers is achieved by the excellent planarity of the semiconducting polymer.

Bottom-contact bottom-gate organic field-effect transistors (OFETs) are fabricated using a low band gap pDTTDPP-DT polymer as a channel material and single-layer graphene (SLG) or Au source/drain electrodes. The SLG-based ambipolar OFETs significantly outperform the Au-based ambipolar OFETs, and thermal annealing effectively improves the carrier mobilities of the pDTTDPP-DT films. The difference is attributed to the following facts: (i) the thermally annealed pDTTDPP-DT chains on the SLG assume more crystalline features with an edge-on orientation as compared to the polymer chains on the Au, (ii) the morphological features of the thermally annealed pDTTDPP-DT films on the SLG electrodes are closer to the features of those on the gate dielectric layer, and (iii) the SLG electrode provides a flatter, more hydrophobic surface that is favorable for the polymer crystallization than the Au. In addition, the preferred carrier transport in each electrode-based OFET is associated with the HOMO/LUMO alignment relative to the Fermi level of the employed electrode. All of these experimental results consistently explain why the carrier mobilities of the SLG-based OFET are more than 10 times higher than those of the Au-based OTFT. This work demonstrates the strong dependence of ambipolar carrier transport on the source/drain electrode and annealing temperature.

We report the development of a novel hole transporting material (HTM), PCP-TPA, based on [2,2]paracyclophane. In comparison to the well-known HTM, spiro-OMeTAD, PCP-TPA could be prepared using a simple synthesis and showed a higher hole mobility due to effective intermolecular aggregation in the film state. When used as a HTM in perovskite solar cells, the power conversion efficiency reached 17.6%. PCP-TPA will potentially replace spiro-OMeTAD and advance the development of cost-effective and practical perovskite solar cells.

We characterized the electrical properties of a field-effect transistor (FET) and a nonvolatile memory device based on a solution-processable low bandgap small molecule, Si1TDPP-EE-C6. The small molecule consisted of electron-rich thiophene-dithienosilole-thiophene (Si1T) units and electron-deficient diketopyrrolopyrrole (DPP) units. The as-spun Si1TDPP-EE-C6 FET device exhibited ambipolar transport properties with a hole mobility of 7.3×10(-5) cm2/(Vs) and an electron mobility of 1.6×10(-5) cm2/(Vs). Thermal annealing at 110 °C led to a significant increase in carrier mobility, with hole and electron mobilities of 3.7×10(-3) and 5.1×10(-4) cm2/(Vs), respectively. This improvement is strongly correlated with the increased film crystallinity and reduced π-π intermolecular stacking distance upon thermal annealing, revealed by grazing incidence X-ray diffraction (GIXD) and atomic force microscopy (AFM) measurements. In addition, nonvolatile memory devices based on Si1TDPP-EE-C6 were successfully fabricated by incorporating Au nanoparticles (AuNPs) as charge trapping sites at the interface between the silicon oxide (SiO2) and cross-linked poly(4-vinylphenol) (cPVP) dielectrics. The device exhibited reliable nonvolatile memory characteristics, including a wide memory window of 98 V, a high on/off-current ratio of 1×10(3), and good electrical reliability. Overall, we demonstrate that donor-acceptor-type small molecules are a potentially important class of materials for ambipolar FETs and nonvolatile memory applications.

Recently, single-port surgery for colon cancer has been increasingly attempted. However, prospective studies investigating the efficacy of single-port colectomy for colon cancer are lacking. The aim of this study is to determine whether single-port colectomy for sigmoid colon cancer is a safe and effective surgical option.Forty-eight patients were enrolled for this prospective single-arm Phase II trial. All patients underwent single-port laparoscopic-assisted sigmoidectomy through the umbilicus. The primary outcome was the number of retrieved lymph nodes. Secondary measures included the conversion rate, postoperative morbidities, mortalities, and short-term clinical outcomes.The mean number of retrieved lymph nodes was 21.1 (95% confidence interval, 18.1-23.99). The conversion rate was 14.6% (open conversion, 4.2%), and the overall proportion of morbidity was 31.2%. The majority of complications involved wound problems (18.8%); the mortality rate was 0%. The median postoperative hospital stay was 8 days (range, 7-12 days), and the median time from surgery until the first episode of flatus was 3 days (range, 1-5 days).Single-port colectomy for sigmoid colon cancer is safe and oncologically feasible in selected patients. Considering the relatively high conversion rates, improvement of the instruments for single-port colectomy is needed.

We report the synthesis, characterization, and solar cell properties of new donor–acceptor-type low band gap polymers (POBDTPD and PEBDTPD) that incorporate dialkoxybenzodithiophene (BDT) as the donor and N-octyl-2,7-dithia-5-azacyclopenta[a]pentalene-4,6-dione (DTPD) as the acceptor. The newly developed DTPD moiety was carefully designed to lower a band gap via strong interaction between donor–acceptor moieties and keep polymer energy levels deep. Remarkably, the DTPD acceptor moiety effectively widens the light absorption range of the polymers up to ∼900 nm while positioning their HOMO and LUMO levels in the optimal range, i.e., −5.3 and −4.0 eV, respectively, for high power conversion efficiencies (PCEs) as we intended. Solar cell devices were fabricated according to the structure ITO/PEDOT:PSS/photoactive (polymer:PC70BM)/TiO2/Al. The POBDTPD devices exhibited a PCE of 4.7% with a Voc of 0.70 V, a Jsc of 10.6 mA/cm2, and a FF of 0.64. The PEBDTPD devices yielded a higher PCE of 5.3% with a Voc of 0.72...

The outcomes of colorectal cancer are determined by host factors, including systemic inflammation. The purpose of this study was to evaluate the prognostic significance of fibrinogen and inflammation-based scores, as markers of the inflammatory response, in colon cancer.We retrospectively reviewed the medical records of patients with nonmetastatic colon cancer who underwent curative resection between January 2005 and December 2007. Fibrinogen, albumin, C-reactive protein, neutrophil, lymphocyte, and platelet counts were measured at the time of diagnosis. Correlations between preoperative plasma fibrinogen levels and clinicopathologic characteristics were analyzed. Univariate and multivariate survival analyses were performed to identify factors associated with disease-free and overall survival.A total of 624 patients who underwent curative resection for colon cancer were eligible for this study. Mean preoperative plasma fibrinogen levels were 325.24±88.19 mg/dl. Higher preoperative plasma fibrinogen levels were associated with sex (male), old age, poorly/mucinous differentiated tumor, advanced tumor stage, elevated carcinoembryonic antigen (CEA) levels, higher modified Glasgow Prognostic Score, and higher neutrophil:lymphocyte and platelet:lymphocyte ratios. In multivariate analysis, elevated plasma fibrinogen level [disease-free survival: hazard ratio (HR) 1.999, 95% confidence interval (95% CI) 1.081-3.695, P=.027; overall survival: HR 3.138, 95% CI 1.077-9.139, P=.036], advanced tumor stage, and higher CEA levels were independently associated with worse disease-free survival and overall survival. None of the inflammation-based scores were significantly associated with survival.Fibrinogen as one of inflammatory markers may be considered a possible prognostic marker in colon cancer.

We fabricated perovskite solar cells with enhanced device efficiency based on vertically oriented TiO2 nanostructures using a nanoporous template of block copolymers (BCPs). The dimension and shape controllability of the nanopores of the BCP template allowed for the construction of one-dimensional (1-D) TiO2 nanorods and two-dimensional (2-D) TiO2 nanowalls. The TiO2 nanorod-based perovskite solar cells showed a more efficient charge separation and a lower charge recombination, leading to better performance compared to TiO2 nanowall-based solar cells. The best solar cells employing 1-D TiO2 nanorods showed an efficiency of 15.5% with VOC = 1.02 V, JSC = 20.0 mA cm(-2) and fill factor = 76.1%. Thus, TiO2 nanostructures fabricated from BCP nanotemplates could be applied to the preparation of electron transport layers for improving the efficiency of perovskite solar cells.

The purpose of the present study was to compare the direct costs of laparoscopic surgery (LS) and open surgery (OS) in the treatment of mid or low rectal cancer after preoperative chemoradiotherapy in patients in Korea. The records of 130 LS patients and 125 OS patients were reviewed. Hospital stay after surgery and overall complication rates within three months of surgery were not significantly different. The LS group had significantly higher median costs than the OS group ($7,467.30 vs. $5,667.00; P

Although small rectal carcinoid tumors can be treated using local excision, complete resection can be difficult because tumors are located in the submucosal layer. We evaluate the factors associated with pathologically complete local resection of rectal carcinoid tumors. Data were analyzed of 161 patients with 166 rectal carcinoid tumors who underwent local excision with curative intent from January 2001 to December 2010. A pathologically complete resection (P-CR) was defined as an en bloc resection with tumor-free lateral and deep margins. The study classified treatments into three categories for analysis: conventional polypectomy (including strip biopsy, snare polypectomy, and hot biopsy), advanced endoscopic techniques (including endoscopic mucosal resection with cap and endoscopic submucosal dissection), and surgical local excision (including transanal excision and transanal endoscopic microsurgery). We evaluated the P-CR rate according to treatment method, tumor size, initial endoscopic impression and the use of endoscopic ultrasound (EUS) or transrectal ultrasound (TRUS). The mean tumor size was 5.51 ± 2.43 mm (range 2–18 mm) and all lesions were confined to the submucosal layer. The P-CR rates were 30.9, 72.0, and 81.8 % for conventional polypectomy, advanced endoscopic techniques, and surgical local excision, respectively. Univariate analysis showed that P-CR was associated with treatment method, use of EUS or TRUS, and initial endoscopic impression. Multivariate analysis showed that only treatment method was associated with P-CR. Pathologically complete resection of small rectal carcinoid tumors was more likely to be achieved when using advanced endoscopic techniques or surgical local excision rather than conventional polypectomy.

Copper-indium-selenide (CISe) quantum dots (QDs) are a promising alternative to the toxic cadmium- and lead-chalcogenide QDs generally used in photovoltaics due to their low toxicity, narrow band gap, and high absorption coefficient. Here, we demonstrate that the photovoltaic performance of CISe QD-sensitized solar cells (QDSCs) can be greatly enhanced simply by optimizing the thickness of ZnS overlayers on the QD-sensitized TiO2 electrodes. By roughly doubling the thickness of the overlayers compared to the conventional one, conversion efficiency is enhanced by about 40%. Impedance studies reveal that the thick ZnS overlayers do not affect the energetic characteristics of the photoanode, yet enhance the kinetic characteristics, leading to more efficient photovoltaic performance. In particular, both interfacial electron recombination with the electrolyte and nonradiative recombination associated with QDs are significantly reduced. As a result, our best cell yields a conversion efficiency of 8.10% under standard solar illumination, a record high for heavy metal-free QD solar cells to date.

For the commercial development of organic photovoltaics (OPVs), laboratory-scale OPV technology must be translated to large area modules. In particular, it is important to develop high-efficiency polymers that can form thick (>100 nm) bulk heterojunction (BHJ) films over large areas with optimal morphologies for charge generation and transport. Here, D1-A-D2-A random terpolymers composed of 2,2′-bithiophene with various proportions of 5,6-difluoro-4,7-bis(thiophen-2-yl)-2,1,3-benzothiadiazole and 5,6-difluoro-2,1,3-benzothiadiazole (FBT) are synthesized. It is found that incorporating small proportions of FBT into the polymer not only conserves the high crystallinity and favorable face-on orientation of the D-A copolymer FBT-Th4 but also improves the nanoscale phase separation of the BHJ film. Consequently, the random terpolymer PDT2fBT-BT10 exhibits a much improved solar cell efficiency of 10.31% when compared to that of the copolymer FBT-Th4 (8.62%). Moreover, due to this polymer's excellent processability and suppressed overaggregation, OPVs with 1 cm2 active area based on 351 nm thick PDT2fBT-BT10 BHJs exhibit high photovoltaic performance of 9.42%, whereas rapid efficiency decreases arise for FBT-Th4-based OPVs for film thicknesses above 300 nm. It is demonstrated that this random terpolymer can be used in large area and thick BHJ OPVs, and guidelines for developing polymers that are suitable for large-scale printing technologies are presented.

Organic-inorganic hybrid tandem solar cells attract a considerable amount of attention due to their potential for realizing high efficiency photovoltaic devices at a low cost. Here, highly efficient triple-junction (TJ) hybrid tandem solar cells consisting of a double-junction (DJ) amorphous silicon (a-Si) cell and an organic photovoltaic (OPV) rear cell were developed. In order to design the TJ device in a logical manner, a simulation was carried out based on optical absorption and internal quantum efficiency. In the TJ architecture, the high-energy photons were utilized in a more efficient way than in the previously reported a-Si/OPV DJ devices, leading to a significant improvement in the overall efficiency by means of a voltage gain. The interface engineering such as tin-doped In2O3 deposition as an interlayer and its UV-ozone treatment resulted in the further improvement in the performance of the TJ solar cells. As a result, a power conversion efficiency of 7.81% was achieved with an open-circuit voltage of 2.35 V. The wavelength-resolved absorption profile provides deeper insight into the detailed optical response of the TJ hybrid solar cells.

Here we present synthesis and electronic properties of a new alternating copolymer composed of dithieno[2,3-d;2',3'-d'] benzo[1,2-b; 4,5-b'] dithiophene (DTBDT) and diketopyrrolopyrrole units, poly dithienobenzodithiophene-co-diketopyrrolopyrrolebithiophene (PDPDBD). The resulting polymer showed hysteresis free, fast switching and highly reliable organic thin-film transistor properties comparable to a-Si. Hole mobility of the polymer is about 2.7 cm(2)V(-1)s(-1), which is remarkably improved compared with its benzodithiophene (BDT)-analougue that contains a smaller aromatic ring of BDT in the place of DTBDT. This is mainly due to much increased intramolecular charge transport originated from PDPDBD's rigid molecular backbone. Furthermore, photoconductor devices fabricated by using PDPDBD as an active layer showed a high performance with the highest photoconductive gain of similar to 10(5). Taken together, the successful PDPDBD's transistor and photoconductor performances with high device stability demonstrated practical applicability of PDPDBD in low-cost and flexible optoelectronic devices.

We report the achievement of a power conversion efficiency (PCE) improvement in P3HT:PCBM-based bulk-heterojunction type polymer solar cells using photocrosslinked P3HT (c-P3HT) as the electron blocking/hole extraction layer and titanium oxide nanoparticles (TiO2) as the hole blocking/electron extraction layer. Devices prepared with a 20 nm thick c-P3HT layer showed an improved PCE of 3.4% compared to devices prepared without the c-P3HT layer (PCE = 3.0%). This improvement was attributed to an extension in the carrier lifetime and an enhancement in the carrier mobility. The incorporation of the c-P3HT layer lengthened (by more than a factor of 2) the carrier lifetime and increased (by a factor of 5) the hole mobility. These results suggest that the c-P3HT layer not only prevented non-geminate recombination but it also improved carrier transport. The PCE was further improved to 4.0% through the insertion of a TiO2 layer that acted as an effective hole-blocking layer at the interface between the photoactive layer and the cathode. This work demonstrates that the incorporation of solution-processable hole and electron blocking/extraction layers offers an effective means for preventing nongeminate recombination at the interfaces between a photoactive layer and an electrode in bulk-heterojunction-type polymer solar cells.

A series of anionic self-doped conjugated polyelectrolytes (CPEs) by copolymerization of a 1,4-bis(4-sulfonatobutoxy)benzene moiety with different counter monomers of thiophene, bithiophene, and terthiophene is reported. The CPEs show high conductivity of ≈10−4 S cm−1 due to being self-doped in a neutral state and exhibit excellent hole transporting property in the out-of-plane direction, compared with poly(3,4-ethylenedioxythiophene):poly(styrene-sulfonate) (PEDOT:PSS). Moreover, the CPE incorporating a less electron-donating unit from terthiophene to thiophene exhibits a higher work function and therefore, PhNa-1T incorporating thiophene shows a relatively high work function of 5.21 eV than 4.97 eV of PEDOT:PSS. This can induce a higher internal field in the solar cell device, facilitating efficient charge collection to the electrode. As a result, polymer solar cell devices incorporating the CPEs as a hole transporting layer achieve enhanced photovoltaic performances from those of the conventional PEDOT:PSS-based devices. The solar cell efficiency reaches up to 9.89%, which is among the highest values demonstrated by PCE-10-based normal-type organic solar cells.

Molecular packing structures and photoinduced charge separation dynamics have been investigated in a recently developed bulk heterojunction (BHJ) organic photovoltaic (OPV) material based on poly(thienothiophene-benzodithiophene) (PTB1) with a power conversion efficiency (PCE) of5% in solar cell devices. Grazing incidence X-ray scattering (GIXS) measurements of the PTB1:PCBM ([6,6]-phenyl-C(61)-butyric acid methyl ester) films revealed pi-stacked polymer backbone planes oriented parallel to the substrate surface, in contrast to the pi-stacked polymer backbone planes oriented perpendicular to the substrate surface in regioregular P3HT [poly(3-hexylthiophene)]:PCBM films. A approximately 1.7 times higher charge mobility in the PTB1:PCBM film relative to that in P3HT:PCBM films is attributed to this difference in stacking orientation. The photoinduced charge separation (CS) rate in the pristine PTB1:PCBM film is more than twice as fast as that in the annealed P3HT:PCBM film. The combination of a small optical gap, fast CS rate, and high carrier mobility in the PTB1:PCBM film contributes to its relatively high PCE in the solar cells. Contrary to P3HT:PCBM solar cells, annealing PTB1:PCBM films reduced the device PCE from 5.24% in the pristine film to 1.92% due to reduced interfacial area between the electron donor and the acceptor. Consequently, quantum yields of exciton generation and charge separation in the annealed film are significantly reduced compared to those in the pristine film.

Purpose Since the publication of Dialysis Outcomes Quality Initiative (DOQI) guidelines, the use of native veins for the construction of arteriovenous fistulas (AVF) for hemodialysis has been highly recommended rather than prosthetic arteriovenous grafts (AVG). Upper arm basilic vein transposition (BVT) has been accepted widely, with superior patency compared with AVG, but only a few studies have reported outcomes of forearm BVT (FBVT). This study evaluated the efficacy of FBVT compared with direct AVF (DAVF) and AVG in a tertiary referral center. Methods From January 2005 to December 2007, 461 patients underwent AV access for hemodialysis in Seoul National University Hospital. We retrospectively reviewed the medical records and dialysis sheets and evaluated the current AVF function in the outpatient clinic or by telephone interviews. Patients were grouped by the operation type: DAVF, FBVT, and AVG. The outcomes compared were primary, assisted-primary and secondary patency rates, maturation failure, and complications. Result The mean age was 59 years (range, 14-92 years), and 280 patients (60.7%) were male. By operation type, the 461 accesses were 389 DAVF (84.4%), 34 FBVT (7.4%), and 38 AVG (8.2%). Mean follow-up duration was 21 months (range, 1-51 months). The primary patency rates for DAVF, FBVT, and AVG were 67.6%, 41.5%, 35% at 12 months and 53.9%, 30.2%, 10.3% at 24 months, respectively. The secondary patency rates were 89.2%, 79.1%, 78.3% at 12 months and 83.8%, 74.4%, 64.9% at 24 months, respectively. Maturation failure occurred in five DAVF patients and in one FBVT patient. The infection rate was 0.3% in DAVF and 12.5% in AVG, but no infection occurred in patients with FBVT. Multivariate analysis revealed that age and history of previous access were associated with lower primary patency. Conclusion Forearm BVT showed an acceptable, high 2-year patency rate and fewer thromboses and infectious complications than AVG. Forearm BVT could be considered before forming an upper arm AVF or forearm AVG, if the basilic vein is available.

A new low band gap semiconducting polymer, PTB1, was synthesized and found promising for solar energy harvesting. Simple polymer solar cells based on PTB1 and methanofullerene [6,6]-phenyl-C(71)-butyric acid methyl esters (PC(71)BM) exhibit a solar conversion efficiency of 5.6%. An external quantum efficiency of 67% and fill-factor of 65% are achieved, both of which are among the highest values reported for a solar cell system based on a low band gap polymer.

The effects of 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) doping on diketopyrrolo-pyrrole-based polymeric semiconductors in terms of charge transport behavior and structural ordering are systematically investigated. Although the energy level offset between the polymeric semiconductor and the F4TCNQ acceptor was not particularly large, ultraviolet photoelectron spectroscopy analyses revealed that a low doping ratio of 1 wt. % is sufficient to tune the energy distance between the Fermi level and the HOMO level, reaching saturation at roughly 5 wt. %, which is further confirmed by the depletion mode measurements of field effect transistors (FETs). Structural analyses using grazing-incidence X-ray diffraction (GIXD) show that the overall degree of edge-on orientation is disturbed by the addition of dopants, with significant influence appearing at high doping ratios (>3 wt. %). The calculated charge carrier mobility from accumulation mode measurements of FETs showed a maximum value of 2 cm2/...

Highly efficient solar cells with sustainable performance under severe mechanical deformations are in great demand for future wearable power supply devices. In this regard, numerous studies have progressed to implement flexible architecture to high-performance devices such as perovskite solar cells. However, the absence of suitable flexible and stretchable materials has been a great obstacle in the replacement of largely utilized transparent conducting oxides that are limited in flexibility. Here, a shape recoverable polymer, Noland Optical Adhesive 63, is utilized as a substrate of perovskite solar cell to enable complete shape recovery of the device upon sub-millimeter bending radii. The employment of stretchable electrodes prevents mechanical damage of the perovskite layer. Before and after bending at a radius of 1 mm, power conversion efficiency (PCE) is measured to be 10.75% and 10.4%, respectively. Additionally, the shape recoverable device demonstrates a PCE of 6.07% after crumpling. The mechanical properties of all the layers are characterized by nanoindentation. Finite element analysis reveals that the outstanding flexibility of the perovskite layer enables small plastic strain distribution on the deformed device. These results clearly demonstrated that this device has great potential to be utilized in stretchable power supply applications.

In order to improve the interconnection of TiO 2 photoelectrode for the flexible dye-sensitized solar cells (DSSCs) with plastic substrates, thin TiO 2 layers are additionally introduced to the surface of main TiO 2 nanoparticles by atomic layer deposition (ALD) at low temperature. The ALD-induced TiO 2 thin layers on porous films effectively reduced the internal electrical resistance, leading to the facilitated electron transport in DSSCs. As a result, DSSCs with ALD-induced TiO 2 thin layers (thickness of ~ 1.5 nm) showed better power conversion efficiency of 3.09%, which is 33% enhancement compared with that without ALD-induced TiO 2 thin layers (2.32%).

Intense pulsed white light (IPWL) sintering was carried out at room temperature, which is suitable dye-sensitized solar cells (DSSCs) fabrication process on plastic substrates for the mass production. Five seconds irradiation of IPWL on TiO2 electrode significantly improves the photocurrent density and power conversion efficiency of DSSCs by more than 110% and 115%, respectively, compared to the DSSCs without IPWL treatment. These improvements were mainly attributed to the enhanced interconnection between the TiO2 nanoparticles induced by IPWL illumination, which is confirmed by the impedance spectra analysis.

The natural history of gastric cancer is unclear. We report here on a rare case of advanced gastric cancer for which we performed curative gastrectomy 78 months after the diagnosis. A 74-year-old woman with epigastric pain underwent esophagogastroscopy in January, 2000 and she was diagnosed with advanced gastric cancer. Suspicious omental cake was noted on CT. After refusing all kinds of treatment, she underwent a follow up CT scan on September, 2002, which no longer suggested omental cake. She once again refused treatment, but she visited the hospital in June, 2006 due to severe epigastric pain and a decreased oral intake. Abdominal CT showed no distant metastasis, and so radical subtotal gastrectomy with regional lymph node dissection was performed in July, 2006 and the TNM stage was T2bN1M0 (stage II).