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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.

Correction for ‘Crystallinity-modulated hollow CeO2−x nanorods as free radical scavengers for long-term photostability in organic photovoltaics’ by Seongwon Yoon et al., J. Mater. Chem. C, 2023, 11, 970–979, https://doi.org/10.1039/D2TC04152A.

Here, we develop a method to prepare a dopant-free hole transporting material by blending an organic semiconductor and a conjugated polymer with 1,8-diiodooctane (DIO) additive. The normal-type solar cell based on the hole transporting material (HTM) blend with DIO + PCDTBT shows enhanced efficiency up to 18.0% compared to 14.7% for the device using the pristine small molecule. Incorporation of DIO results in increased crystallinity, while the conjugated polymer induces an intermolecular network for efficient charge transport with improved film morphology. Consequently, the HTM blend with DIO + PCDTBT shows a higher hole mobility and more efficient charge transfer at the perovskite/hole transporting layer interface compared with the pristine HTM. Furthermore, the solar cell introducing the HTM blend with DIO shows high mechanical and moisture stability; the compact and homogeneous film of high crystalline HTM shows more adhesive contact with perovskite and effectively prevents the penetration of moisture. The efficiency of the unencapsulated device using a small molecular HTM decreases to 60%, whereas the corresponding device with HTM blend maintains 80% performance after storage under 85% relative humidity and 85 °C.

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.

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.

Molybdenum disulfide (MoS 2 ) is a promising material for use as a low-cost electrocatalytic counter electrode (CE) in photoelectrochemical dye-sensitized solar cells (DSSCs). However, currently, the MoS 2 CEs are generally prepared with a high temperature sintering for the synthesis and crystallization of MoS 2 . Here, we report a simple and rapid method for the preparation of highly efficient MoS 2 CEs. The MoS 2 films were synthesized at 70 °C, followed by sintering with a near-infrared (IR) pulsed laser for 1 min. Compared to the conventional heat-sintered MoS 2 CE, the laser-sintered CE showed enhanced crystallinity and improved interconnection between the MoS 2 particles, resulting in superior electrocatalytic activity towards the I − /I 3 − redox couple. When used in a DSSC, the laser-sintered MoS 2 CE exhibited a higher conversion efficiency ( η = 7.19%) compared to that of the heat-sintered CE ( η = 5.96%). Furthermore, the laser-sintered CE had a comparable conversion efficiency compared to that of the conventional Pt CE ( η = 7.42%).

Highly crumpled graphene-based three dimensional (3D) interconnected and hierarchically porous conducting networks were prepared for application as electrocatalytic counter electrode (CE) in dye-sensitized solar cells (DSSCs). Finely and hierarchically crumpled graphene was synthesized from Fe 2 O 3 /graphene oxide (GO) hybrids via a one-step chemical etching–reduction process with HI solution. The synthesized crumpled graphene exhibited not only 24 times higher specific surface area, but also superior dispersibility in aqueous solution compared to conventional reduced graphene oxide (rGO). Owing to its superior solution processability and comparable electrical conductivity, the crumpled graphene could be assembled into 3D interconnected films on the substrates simply by drop casting, without any binders. In addition, although the crumpled graphene was not modified by dopants or high-temperature annealing, it showed much higher electrocatalytic activity for the I − /I 3 − redox couple compared to that of rGO, which is mainly attributed to its significantly larger accessible surface area for electrochemical reduction. As a result, the DSSC containing the crumpled graphene CE exhibited 2.8 times enhanced conversion efficiency (η = 5.15%) compared to that containing a rGO electrode (η = 1.86%).

To transfer spin-coating based high performance polymer solar cells (PSCs) to large area using roll-to-roll compatible solution process, it is important to understand effect of the processing method and materials on morphology of bulk-heterojunction (BHJ) films. We developed PBDB-T based PSCs modules using PC71BM or nonfullerene acceptor ITIC with blade coating. It is found that crystallization of ITIC and its following aggregation are significantly affected by solvent drying dynamics which is induced by thermal heating whereas PC71BM shows similar BHJ morphology regardless heating temperature. We studied mechanism and effects of acceptors on BHJ film forming during the coating. ITIC-solvent interaction makes ITIC to form high crystalline structures and but, large aggregated domains during slow solvent evaporation at room temperature. Such aggregated morphology of PBDB-T:ITIC is much improved to optimal morphology for effective charge generation and transporting with a 50 °C heating process. As a result, PBDB-T:ITIC photovoltaic module (active area 58.5 cm2) prepared at 50 °C showed much enhanced efficiency of 9.03% than 5.0% of room temperature processed one. This result is among the highest performance of large active-area PSC modules and provides research guidelines for efficient transfer of spin-coating based small cell technology to roll-to-roll based large-area PSC modules.

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.

Preparation of well-interconnected TiO2 electrodes at low temperature is critical for the fabrication of highly efficient dye-sensitized solar cells (DSCs) on plastic substrates. Herein we explore a synergistic approach using a combination of chemical and physical sintering. We formulate a binder-free TiO2 paste based on “nanoglue” as the chemical sintering agent, and use it to construct a photoelectrode on plastic by low-temperature physical compression to further improve the connectivity of TiO2 films. We systematically investigated the factors affecting the photovoltaic performance and found the conditions to achieve electron diffusion lengths as long as 25 mm and charge collection efficiencies as high as 95%, as electrochemical impedance spectroscopy measurements indicate. We apply this approach to obtain a DSC deposited on plastic displaying 6.4% power conversion efficiency based on commercial P25 titania particles

Low bandgap polymers with dithienylquinoxaline moieties based on 6H-phenanthro[1,10,9,8-cdefg]carbazole were synthesized via the Suzuki coupling reaction. Alkoxy groups were substituted at two different positions on the phenyl groups of the quinoxaline units of these polymers: in the para-position (PPQP) and in the meta-position (PPQM). The two polymers showed similar physical properties: broad absorption in the range of 400–700 nm, optical bandgaps of ∼1.8 eV, and the appropriate frontier orbital energy levels for efficient charge transfer/separation at polymer/PC71BM interfaces. However, the PPQM solar cell achieved a higher PCE due to its higher Jsc. Our investigation of the morphologies of the polymer:PC71BM blend films and theoretical calculations of the molecular conformations of the polymer chains showed that the polymer with the meta-positioned alkoxy group has better miscibility with PC71BM than the polymer with the para-positioned alkoxy group because the dihedral angle of its phenyl group with respect to the quinoxaline unit is higher. This higher miscibility resulted in a polymer:PC71BM blend film with a better morphology and thus in a higher PCE. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 796–803

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.

Solar cells based on the photovoltaic effect are an effective method to convert solar energy into electricity. It has become attractive to find solar cell technologies which exhibit lower manufacturing costs by utilizing inexpensive and abundant materials. Some additional advantages conveyed by organic solar cells are that they are lightweight and flexible and allow for scalable material production and cost effective roll-to-roll coating and printing techniques. Efficiency of >10% was disclosed in small area solar cells with various device architectures, which indicated the rapid progress over the last several years and the great potential of organic solar cells as an alternative source of energy. In order for organic solar cells to fully mature from research and development into cost effective products, solar cell technology at a small size needs to be realized at a large scale. And for this, it is highly important to develop new conjugated polymers and understand the fundamental working mechanism of the materials. In the presentation, we developed new conjugated polymers for large-area solar cell technologies and studied the effects of conjugated polymers on solution processing and photovoltaic performance in large area organic solar cells.

A molecular design is presented for tailoring the energy levels in D-π-A organic dyes through fluorination of their acceptor units, which is aimed at achieving efficient dye-sensitized solar cells (DSSCs). This is achieved by exploiting the chemical structure of common D-π-A organic dyes and incorporating one or two fluorine atoms at the ortho-positions of the cyanoacetic acid as additional acceptor units. As the number of incorporated fluorine atoms increases, the LUMO energy level of the organic dye is gradually lowered due to the electron-withdrawing effect of fluorine, which ultimately results in a gradual reduction of the HOMO-LUMO energy gap and an improvement in the spectral response. Systematic investigation of the effects of incorporating fluorine on the photovoltaic properties of DSSCs reveals an upshift in the conduction-band potential of the TiO2 electrode during impedance analysis; however, the incorporation of fluorine also results in an increased electron recombination rate, leading to a decrease in the open-circuit voltage (Voc). Despite this limitation, the conversion efficiency is gradually enhanced as the number of incorporated fluorine atoms is increased, which is attributed to the highly improved spectral response and photocurrent.

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.

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.

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).