Tribology of Pore-Textured Hard Surfaces under Physiological Conditions: Effects of Texture Scales.

Micro- and nanotexturing on hard biomaterials have shown advantages for tissue engineering and antifouling applications. However, a growing number of studies have also shown that texturing may cause an increase in friction, demanding further research on the tribological effects of texturing under physiological conditions. This study investigates the tribological effects of micro- and nanopore patterns on hard hydrophilic silicon sliding against soft hydrophobic polydimethylsiloxane (PDMS) immersed in aqueous liquids with various viscosities, simulating the sliding of a textured implant surface against soft tissues. The experimental results show that silicon surfaces with pore textures at both micro- and nanoscale feature sizes confer a higher coefficient of friction (COF) than an untextured one. It is attributed to the texture's edge effect caused by the periodic pore patterns between the two sliding objects with a large difference in material stiffness. For the same solid area fraction, nanopored surfaces show a higher COF than micropored surfaces because of the significantly higher texture edge length per unit area. For micropored surfaces with a similar length of texture edge length per unit area, the COF increases more significantly with the increase in pore size because of the greater stress at the rims of the larger pores. The COFs of both micro- and nanoscale pores generally decrease from ∼10 to 0.1 with an increase in the surrounding aqueous viscosity, indicating the transition from a boundary lubrication to a mixed lubrication regime while mostly remaining in boundary lubrication. In contrast, the COF of an untextured surface decreases from ∼1 to 0.01, indicating that it mostly remains in the mixed lubrication regime while showing the tendency toward hydrodynamic lubrication. Compared to a hydrophilic hard probe sliding against a textured hydrophobic soft substrate, the hydrophobic soft probe sliding against a textured hydrophilic hard substrate produces a significantly higher COF under similar physiological conditions due to the larger edge effect.

Comparison of the Pharmacokinetics of CT-P13 Between Crohn's Disease and Ulcerative Colitis.

BACKGROUND: We aimed to compare trough infliximab levels and the development of antidrug antibody (ADA) for 1 year between Crohn's disease (CD) and ulcerative colitis (UC) patients who were biologic-naive, and to evaluate their impact on clinical outcomes. METHODS: This was a prospective, multicenter, observational study. Biologic-naive patients with moderate to severe CD or UC who started CT-P13, an infliximab biosimilar, therapy were enrolled. Trough drug and ADA levels were measured periodically for 1 year after CT-P13 initiation. RESULTS: A total of 267 patients who received CT-P13 treatment were included (CD 168, UC 99). The rates of clinical remission (72% vs. 32.3%, P <0.001) at week 54 were significantly higher in CD than in UC. The median trough drug level (µg/mL) was significantly higher in CD than in UC up to week 14 (week 2, 18.7 vs. 14.7, P <0.001; week 6, 12.5 vs. 8.6, P <0.001; week 14, 3.4 vs. 2.5, P =0.001). The median ADA level (AU/mL) was significantly lower in CD than in UC at week 2 (6.3 vs. 6.5, P =0.046), week 30 (7.9 vs. 11.8, P =0.007), and week 54 (9.3 vs. 12.3, P =0.032). Development of ADA at week 2 [adjusted odds ratio (aOR)=0.15, P =0.026], initial C-reactive protein level (aOR=0.87, P =0.032), and CD over UC (aOR=1.92, P <0.001) were independent predictors of clinical remission at week 54. CONCLUSION: Infliximab shows more favorable pharmacokinetics, including high drug trough and low ADA levels, in CD than in UC, which might result in better clinical outcomes for 1-year infliximab treatment in CD patients.

Enrichment of Activated Fibroblasts as a Potential Biomarker for a Non-Durable Response to Anti-Tumor Necrosis Factor Therapy in Patients with Crohn's Disease.

We investigated whether the response to anti-tumor necrosis factor (anti-TNF) treatment varied according to inflammatory tissue characteristics in Crohn's disease (CD). Bulk RNA sequencing (RNA-seq) data were obtained from inflamed and non-inflamed tissues from 170 patients with CD. The samples were clustered based on gene expression profiles using principal coordinate analysis (PCA). Cellular heterogeneity was inferred using CiberSortx, with bulk RNA-seq data. The PCA results displayed two clusters of CD-inflamed samples: one close to (Inflamed_1) and the other far away (Inflamed_2) from the non-inflamed samples. Inflamed_1 was rich in anti-TNF durable responders (DRs), and Inflamed_2 was enriched in non-durable responders (NDRs). The CiberSortx results showed that the cell fraction of activated fibroblasts was six times higher in Inflamed_2 than in Inflamed_1. Validation with public gene expression datasets (GSE16879) revealed that the activated fibroblasts were enriched in NDRs over Next, we used DRs by 1.9 times pre-treatment and 7.5 times after treatment. Fibroblast activation protein (FAP) was overexpressed in the Inflamed_2 and was also overexpressed in the NDRs in both the RISK and GSE16879 datasets. The activation of fibroblasts may play a role in resistance to anti-TNF therapy. Characterizing fibroblasts in inflamed tissues at diagnosis may help to identify patients who are likely to respond to anti-TNF therapy.

Efficacy and safety of split-dose bowel preparation with 1 L polyethylene glycol and ascorbate compared with 2 L polyethylene glycol and ascorbate in a Korean population: a phase IV, multicenter, randomized, endoscopist-blinded study.

BACKGROUND AND AIMS: The 1-L polyethylene glycol (PEG)-based bowel preparation agent NER1006 (Plenvu; Norgine, Harefield, UK) has shown high cleansing efficacy and tolerability in clinical trials in Europe and North America. However, no clinical trials have yet been reported in Asia. Therefore, the aim of this study was to evaluate the efficacy and safety of 1L PEG-based bowel preparation with Plenvu compared with 2L PEG plus ascorbate bowel preparation in a Korean population. METHODS: In this multicenter, endoscopist-blinded, randomized study, patients at 9 hospitals in South Korea undergoing colonoscopy received either Plenvu or 2L PEG + ascorbate (2L PEG) with a split dose. The primary endpoint was overall bowel cleansing success (Boston Bowel Preparation Scale [BBPS] score ≥2 for all segments of the colon). Secondary endpoints were high-quality bowel cleansing success (overall, BBPS score = 9; segmental colon, BPPS score = 3), polyp detection rate (PDR), and adenoma detection rate (ADR). RESULTS: Of 360 included patients, cleansing efficacy was analyzed in 346 (Plenvu, 174; 2L PEG, 172). The Plenvu group showed noninferior bowel cleansing success rates compared with 2L PEG (93.10% vs 91.86%; difference, 1.24%; 1-sided 97.5% lower confidence limit, -4.31%; Pnoninferiority < .0001; Psuperiority = .661). The Plenvu group had higher high-quality bowel cleansing success rates for overall and right-sided colon segments than the 2L PEG group (49.43% vs 37.79% [P = .029] and 60.92% vs 48.84% [P = .024], respectively). The PDR was greater with Plenvu than with 2L PEG (48.85% vs 37.79%, P = .038). However, ADR did not differ between the 2 groups (24.71% vs 20.35%, P = .331). Although treatment-emergent adverse events (TEAEs) were slightly higher in the Plenvu group than in the 2L PEG group (65.71% vs 52.91%, P = .015), most TEAEs were mild (85.55%) and most patients recovered without any management (99.23%). CONCLUSIONS: Plenvu showed noninferior overall bowel cleansing success rates comparable with 2L PEG but greater high-quality bowel cleansing in overall and right-sided colon, which might help improve the PDR in the Asian population. (Clinical trial registration number: KCT0005894.).

Orienting and shaping organic semiconductor single crystals through selective nanoconfinement.

For organic semiconductor crystals exhibiting anisotropic charge transport along different crystallographic directions, nanoconfinement is a powerful strategy to control crystal orientation by aligning the fast crystallographic growth direction(s) with the unconfined axis(es) of nanoconfining scaffolds. Here, design rules are presented to relate crystal morphology, scaffold geometry, and orientation control in solution-processed small-molecule crystals. Specifically, organic semiconductor triisopropylsilylethynyl pyranthrene needle-like crystals with a dimensionality of n = 1 and perylene platelike crystals with n = 2 were grown from solution within nanoconfining scaffolds comprising cylindrical nanopores with a dimensionality of m = 1, representing one unconfined dimension along the cylinder axis, and those comprising nanopillar arrays with a dimensionality of m = 2. For m = n systems, native crystal growth habits were preserved while the crystal orientation in n = m direction(s) was dictated by the geometry of the scaffold. For n≠m systems, on the other hand, orientation control was restricted within a single plane, either parallel or perpendicular to the substrate surface. Intriguingly, control over crystal shape was also observed for perylene crystals grown in cylindrical nanopores (n > m). Within the nanopores, crystal growth was restricted along a single direction to form a needle-like morphology. Once growth proceeded above the scaffold surface, the crystals adopted their native growth habit to form asymmetric T-shaped single crystals with concave corners. These findings suggest that nanoporous scaffolds with spatially-varying dimensionalities can be used to grow single crystals of complex shapes.

Topography-Dependent Effective Contact Line in Droplet Depinning.

The mobility of a fakir state droplet on a structured surface is fundamentally determined by the effective length of a microscopic contact line. However, it is largely unknown how the surface topography determines the effective contact line length. Based on the direct measurement of droplet adhesion force and the visualization of contact line, this work shows that effective contact line length is topography dependent as opposed to prior notion. On pored surfaces, contact line is not distorted, and the effective length approaches the droplet apparent perimeter regardless of pore dimensions. On pillared surfaces, the distortion of contact line is significantly dependent on the packing density of the pillar structures so that the effective length is as small as a pillar diameter on densely packed pillars and as large as a pillar perimeter on sparsely-packed pillars, while changing linearly between the two extremes.

Spontaneous Deicing on Cold Surfaces.

Although freezing of a droplet on cold surfaces is a universal phenomenon, its mechanisms are still inadequately understood, especially on the surfaces of which the temperature is lower than -60 °C. Here, we report the unique spontaneous deicing phenomena of a water droplet impacting on cold surfaces with a temperature as low as -120 °C. As a hydrophilic surface is cooled below a critically low temperature (e.g., -57 °C for a silicon surface with a native oxide), the impacting water droplet spontaneously delaminates from the substrate and freezes radially outward in a horizontal plane, as opposed to the typical upward freezing shown on a warmer surface. The self-delamination phenomenon is suppressed or reinstated by the combination of thermal and hydrophobic modifications of the surface, which can be taken advantage of for effective deicing schemes for icephobic surface applications.

Contact Line and Adhesion Force of Droplets on Concentric Ring-Textured Hydrophobic Surfaces.

Advances made in fabrication of patterned surfaces with well-defined dimensions of topographic features and their lateral dissemination drive the progress in interpretation of liquid spreading, adhesion, and retreat on engineered solid surfaces. Despite extensive studies on liquid droplet spreading and adhesion on textured surfaces in recent years, conformation of the three-phase contact line and its effect on macroscopic contact angle and droplet adhesion remain the focus of intensive debate. Here, we investigate the effect of surface topography on the adhesion force of Cassie-Baxter-state droplets on concentric ring-textured hydrophobic surfaces having rings with lateral dimensions of 5, 10, and 45 µm and separated by 5, 6, and 7 µm trenches, respectively, with fixed depth of 15 µm. Unlike mostly tested surfaces textured with straight ridges, pores, and pillars, where the droplet base contact line is anisotropic and its conformation varies along the apparent boundary, concentric rings are symmetrical and reinforce the microscopic contact line to align to a circular one that reflects the shape of the pattern. In this study, adhesion forces were calculated based on surface tension and Laplace pressure forces and were compared with the experimental forces for both water and ethylene glycol droplets having a varying contact diameter on the concentric ring-pattern at the point of maximum adhesion force. Results show that the microscopic contact line of the liquid retains its circular shape controlled by circular rings of the pattern, irrespectively of the droplet base diameter larger than 0.8 mm, and there is a good agreement between the experimental and calculated adhesion forces.

Nationwide validation study of diagnostic algorithms for inflammatory bowel disease in Korean National Health Insurance Service database.

BACKGROUND AND AIM: We conducted a nationwide validation study of diagnostic algorithms to identify cases of inflammatory bowel disease (IBD) within the Korea National Health Insurance System (NHIS) database. METHOD: Using the NHIS dataset, we developed 44 algorithms combining the International Classification of Diseases (ICD)-10 codes, codes for Rare and Intractable Diseases (RID) registration and claims data for health care encounters, and pharmaceutical prescriptions for IBD-specific drugs. For each algorithm, we compared the case identification results from electronic medical records data with the gold standard (chart-based diagnosis). A multiple sampling test verified the validation results from the entire study population. RESULTS: A random nationwide sample of 1697 patients (848 potential cases and 849 negative control cases) from 17 hospitals were included for validation. A combination of the ICD-10 code, ≥ 1 claims for health care encounters, and ≥ 1 prescription claims (reference algorithm) achieved excellent performance (sensitivity, 93.1% [95% confidence interval 91-94.7]; specificity, 98.1% [96.9-98.8]; positive predictive value, 97.5% [96.1-98.5]; negative predictive value, 94.5% [92.8-95.8]) with the lowest error rate (4.2% [3.3-5.3]). The multiple sampling test confirmed that the reference algorithm achieves the best performance regarding IBD diagnosis. Algorithms including the RID registration codes exhibited poorer performance compared with that of the reference algorithm, particularly for the diagnosis of patients affiliated with secondary hospitals. The performance of the reference algorithm showed no statistical difference depending on the hospital volume or IBD type, with P-value < 0.05. CONCLUSIONS: We strongly recommend the reference algorithm as a uniform standard operational definition for future studies using the NHIS database.

High-Definition Chromoendoscopy Versus High-Definition White Light Colonoscopy for Neoplasia Surveillance in Ulcerative Colitis: A Randomized Controlled Trial.

OBJECTIVES: Although chromoendoscopy is currently the recommended mode of surveillance in patients with long-standing ulcerative colitis, it is technically challenging and requires a long procedure time. The aim of this study was to compare the dysplasia detection rate of high-definition white light endoscopy with random biopsy (HDWL-R) vs high-definition chromoendoscopy with targeted biopsy (HDCE-T). METHODS: This was a multicenter, prospective randomized controlled trial involving 9 tertiary teaching hospitals in South Korea. A total of 210 patients with long-standing ulcerative colitis were randomized to undergo either the HDWL-R group (n = 102) or HDCE-T group (n = 108). The detection rates of colitis-associated dysplasia (CAD) or all colorectal neoplasia from each trial arm were compared. RESULTS: There was no significant difference in the CAD detection rate between HDCE-T and HDWL-R groups (4/102, 3.9% vs 6/108, 5.6%, P = 0.749). However, HDCE-T showed a trend toward improved colorectal neoplasia detection compared with HDWL-R (21/102, 20.6% vs 13/108, 12.0%, P = 0.093). The median (range) time for colonoscopy withdrawal between the 2 groups was similar (17.6 [7.0-43.3] minutes vs 16.5 [6.3-38.1] minutes; P=0.212; for HDWL-R and HDCE-T, respectively). The total number of biopsies was significantly larger in the HDWL-R group (34 [12-72]) compared with the HDCE-T group (9 [1-20]; P < 0.001). DISCUSSION: On the basis of our prospective randomized controlled trial, HDCE-T was not superior to HDWL-R for detecting CADs.

Long-term efficacy and safety of CT-P13, a biosimilar of infliximab, in patients with inflammatory bowel disease: A retrospective multicenter study.

BACKGROUND AND AIM: A biosimilar of infliximab, CT-P13 (Remsima®) has the potential to reduce treatment costs and enhance access to biological therapy for inflammatory bowel disease (IBD) patients. However, long-term clinical data on its use for IBD treatment are currently sparse. We aimed to investigate the long-term efficacy and safety of CT-P13 therapy in a large, real-life IBD cohort. METHODS: A total of 368 IBD patients (227 with Crohn's disease [CD] and 141 with ulcerative colitis [UC]) treated with CT-P13 at 16 referral hospitals in Korea between July 2012 and December 2017 were retrospectively analyzed. RESULTS: The cumulative retention rates at years 1, 3, and 5 were 86.1%, 68.5%, and 58.7% and 69.7%, 46.0%, and 26.7% in anti-tumor necrosis factor (TNF)-naïve CD and UC patients, respectively. The clinical response and remission rates at week 14 and at years 1, 3, and 5 were 94.3%, 92.7%, 76.8%, and 17.6% and 78.6%, 82.4%, 72.2%, and 17.6% in anti-TNF-naïve CD and 85.6%, 80.0%, 55.2%, and 6.7% and 42.6%, 59.8%, 44.2%, and 6.7% in anti-TNF-naïve UC patients, respectively. Among patients who switched from the biologic originator to CT-P13, the cumulative retention rates at years 1, 3, and 5 were 88.5%, 66.1%, and 44.8% in CD, and 73.9%, 42.5%, and 42.5% in UC patients, respectively. Significant improvements in disease activity scores were accompanied by marked reductions in inflammatory marker levels, and no unexpected adverse events including death or malignancy occurred during the study period. CONCLUSIONS: Long-term treatment with CT-P13 is effective in inducing and maintaining disease improvement and is well-tolerated in patients with IBD. CT-P13 may be a promising treatment option for IBD.

Endoscopic closure of iatrogenic colon perforation using dual-channel endoscope with an endoloop and clips: methods and feasibility data (with videos).

BACKGROUND: Colon perforation is the most serious complication associated with colonoscopic procedures. We performed a novel purse-string suture technique to close the iatrogenic colonic perforation using dual-channel endoscope with an endoloop and clips. METHODS: Iatrogenic colon perforations developed during diagnostic colonoscopy referred to a tertiary hospital over 10 years were considered for this endoscopic closure. An endoloop was inserted through the left channel of the endoscope and placed around the defect. The first clip was placed at the proximal site of the defect through the other channel of the endoscope, and the endoloop was anchored on the mucosa around the defect. Then, subsequent clips were placed next to previous clips and the endoloop was fixed. After the defect was encircled by the endoloop and clips, the rim of the opening was approximated by fastening the endoloop with a purse-string technique. RESULTS: A total of 8 patients were admitted to our hospital because of iatrogenic colon perforations during diagnostic colonoscopy. Of these, 2 underwent laparoscopic surgery and 6 underwent endoscopic closure by this novel purse-string suture technique. The estimated diameters of the perforations were 20 mm. All cases were successfully treated in the endoscopy unit without sedation or general anesthesia, and recovered without any complication or subsequent operation. Abdominal pain had nearly resolved within 3 days after the procedure in all patients, and only mild peritonitis was observed. CONCLUSIONS: Iatrogenic colon perforation can be treated with a purse-string suture technique using dual-channel endoscope with an endoloop and clips. This technique can be useful for relatively large colon perforations associated with diagnostic colonoscopy.

Gate Voltage Dependence of Low Frequency Noise in Tunneling Field Effect Transistors.

In this paper, the dependency of low frequency noise as a function of the gate voltage was examined for tunneling field effect transistors (TFETs). When the level of gate voltage is low, the tunneling width of the TFETs is large. Thus, electrons move via the trap instead of tunneling directly. On the other hand, when the level of gate voltage is high, the tunneling width of the TFETs becomes narrow. Thus, when the gate voltage is low, the noise level of TFETs is high because electrons pass through the trap. However, when the gate voltage is high, electrons pass directly from valence band of source to conduction band of drain, so the noise level is low. Finding the voltage suitable for this TFET is important to determine the optimum conditions for generating BTBT when measuring TFETs and to reduce noise.

Investigation of Positive Bias Temperature Instability Characteristics of Fully Depleted Silicon on Insulator Tunneling Field Effect Transistor with High-k Dielectric Gate Stacks.

The positive bias temperature instability (PBTI) characteristics of fully depleted silicon on insulator (FD-SOI) tunneling field effect transistor (TFET) are investigated in comparison with those of metal oxide semiconductor field effect transistor (MOSFET) fabricated with the same technology process. Unlike some of the previously reported studies, in which the PBTI lifetime of TFET is much longer than that of MOSFET, in this study, the PBTI lifetime of TFET is found to be shorter than that of MOSFET. This result is very interesting, because degradation of electrical parameters of TFET is mainly affected by local traps near the source junction rather than global traps in the channel region. Large degradation of the electrical parameters of TFET due to PBTI stress would result from large fluctuation of the vertical electric field caused by traps near the source junction. This electric field fluctuation near the local region in TFET has more impact on electrical parameter degradation than channel conductivity fluctuation in MOSFET. Therefore, to improve the reliability characteristics of TFET, evaluation of PBTI characteristics and improvement of the quality of gate oxide near the source junction are essential.

Transmission of Monospecies and Dual-Species Biofilms from Smooth to Nanopillared Surfaces.

The transmission of bacteria in biofilms from donor to receiver surfaces precedes the formation of biofilms in many applications. Biofilm transmission is different from bacterial adhesion, because it involves biofilm compression in between two surfaces, followed by a separation force leading to the detachment of the biofilm from the donor surface and subsequent adhesion to the receiver surface. Therewith, the transmission depends on a balance between donor and receiver surface properties and the cohesiveness of the biofilm itself. Here, we compare bacterial transmission from biofilms of an extracellular-polymeric-substance (EPS)-producing and a non-EPS-producing staphylococcal strain and a dual-species oral biofilm from smooth silicon (Si) donor surfaces to smooth and nanopillared Si receiver surfaces. Biofilms were fully covering the donor surface before transmission. However, after transmission, the biofilms only partly covered the donor and receiver surfaces regardless of nanopillaring, indicating bacterial transmission through adhesive failure at the interface between biofilms and donor surfaces as well as through cohesive failure in the biofilms. The numbers of bacteria per unit volume in EPS-producing staphylococcal biofilms before transmission were 2-fold smaller than in biofilms of the non-EPS-producing strain and of dual species. This difference increased after transmission in the biofilm left behind on the donor surfaces due to an increased bacterial density for the non-EPS-producing strain and a dual-species biofilm. This suggests that biofilms of the non-EPS-producing strain and dual species remained compressed after transmission, while biofilms of the EPS-producing strain were induced to produce more EPS during transmission and relaxed toward their initial state after transmission due to the viscoelasticity conferred to the biofilm by its EPS.IMPORTANCE Bacterial transmission from biofilm-covered surfaces to surfaces is mechanistically different from bacterial adhesion to surfaces and involves detachment from the donor and adhesion to the receiver surfaces under pressure. Bacterial transmission occurs, for instance, in food processing or packaging, in household situations, or between surfaces in hospitals. Patients admitted to a hospital room previously occupied by a patient with antibiotic-resistant pathogens are at elevated infection risk by the same pathogens through transmission. Nanopillared receiver surfaces did not collect less biofilm from a smooth donor than a smooth receiver, likely because the pressure applied during transmission negated the smaller contact area between bacteria and nanopillared surfaces, generally held responsible for reduced adhesion. Biofilm left behind on smooth donor surfaces of a non-extracellular-polymeric-substance (EPS)-producing strain and dual species had undergone different structural changes than an EPS-producing strain, which is important for their possible further treatment by antimicrobials or disinfectants.

Effect of scheduled second-look endoscopy on peptic ulcer bleeding: a prospective randomized multicenter trial.

BACKGROUND AND AIM: This study aimed to investigate the effectiveness of scheduled second-look endoscopy (EGD) with endoscopic hemostasis on peptic ulcer rebleeding and to identify the risk factors related to the need for second-look EGD. METHODS: We prospectively randomized patients who had endoscopically confirmed bleeding peptic ulcer with stigmata of active bleeding, visible vessel, or adherent clot into 2 groups between August 2010 and January 2013. Hemoclip application or thermal coagulation and/or epinephrine injection were allowed for initial endoscopic therapy. The same dosage of proton pump inhibitor was injected intravenously. The study group received scheduled second-look EGD 24 to 36 hours after the initial hemostasis, and further therapy was applied if endoscopic stigmata persisted, as above. Those patients who developed rebleeding underwent operation or radiologic intervention despite the additional endoscopic therapy. Outcome measures included rebleeding, amount of transfusion, duration of hospitalization, and mortality. RESULTS: After initial endoscopic hemostasis, 319 eligible patients were randomized into 2 groups. Sixteen (10.1%) and 9 (5.6%) patients developed rebleeding (P = .132), respectively. There was also no difference in surgical intervention (0, 0% vs 1, .6%, P >.999) or radiologic intervention (3, 1.9% vs 2, 1.2%, P = .683), median duration of hospitalization (6.0 vs 5.0 days, P = .151), amount of transfusion (2.4 ± 1.7 vs 2.2 ± 1.6 units, P = .276), and mortality (2, 1.3% vs 2, 1.2%, P > .999) between the 2 groups. Multivariate analysis showed that grades 3 to 4 of endoscopists' estimation to success of initial hemostasis, history of nonsteroidal anti-inflammatory drug (NSAID) use, and larger amounts of blood transfusions (≥4 units of red blood cells) were the independent risk factors of rebleeding. CONCLUSIONS: A single EGD with endoscopic hemostasis is not inferior to scheduled second-look endoscopy in terms of reduction in rebleeding rate of peptic ulcer bleeding. Repeat endoscopy would be helpful in the patients with unsatisfactory initial endoscopic hemostasis, use of NSAIDs, and larger amounts of transfused blood. (Clinical trial registration number: KCT0000565; 4-2010-0348.).

Spontaneous Spreading of a Droplet: The Role of Solid Continuity and Advancing Contact Angle.

Spontaneous spreading of a droplet on a solid surface is poorly understood from a macroscopic level down to a molecular level. Here, we investigate the effect of surface topography and wettability on spontaneous spreading of a water droplet. Spreading force is measured for a suspended droplet that minimizes interference of kinetic energy in the spontaneous spreading during its contact with solid surfaces of discontinuous (pillar) and continuous (pore) patterns with various shapes and dimensions. Results show that a droplet cannot spread spontaneously on pillared surfaces regardless of their shapes or dimensions because of the solid discontinuity. On the contrary, a droplet on pored surfaces can undergo spontaneous spreading whose force increases with a decrease in the advancing contact angle. Theoretical models based on both the system free energy and capillary force along the contact line validate the direct and universal dependency of the spontaneous spreading force on the advancing contact angle.

Anti-Icing or Deicing: Icephobicities of Superhydrophobic Surfaces with Hierarchical Structures.

Superhydrophobic surfaces have gained tremendous attention for icephobic properties, including anti-icing and deicing. The former is about how much a surface can delay the ice formation, whereas the latter is about how easy the surface can let the ice go off after freezing. In this study, superhydrophobic surfaces with different surface roughnesses and wettabilities were tested for both anti-icing and deicing purposes to investigate their correlation in association with the different surface properties. Anti-icing test was conducted by utilizing an icing wind tunnel to see how much ice gets accumulated on the surfaces in a dynamic condition (i.e., impacting supercooled water droplets by forced wind). For the deicing test, sessile droplets were frozen on the surfaces in a static condition (i.e., no wind) and then the shear adhesion forces were measured to disconnect the frozen ices off from the surfaces. The experimental results show that higher anti-icing efficacy does not necessarily mean higher deicing efficacy because of the different icing mechanisms. Although a superhydrophobic surface with a lower depinning force (or contact angle hysteresis) delays the ice accumulation in a dynamic condition more effectively, the same surface can require higher shear adhesion force for ice grown in a static condition where condensation and wetting state of a droplet are the key factors.

Risk factors and clinical courses of concomitant primary sclerosing cholangitis and ulcerative colitis: a Korean multicenter study.

BACKGROUND: Primary sclerosing cholangitis (PSC) is a rare progressive cholestatic liver disease of unknown causes, but is strongly associated with inflammatory bowel diseases (IBDs), particularly ulcerative colitis (UC). However, studies comparing risk factors and clinical courses of patients with concomitant UC and PSC with those of patients with PSC alone are lacking. METHODS: We retrospectively reviewed patients with PSC diagnosed between 2005 and 2017 in four tertiary hospitals in Korea. We compared the risk factors and outcomes of concomitant UC and PSC (UC-PSC) and those of PSC alone. RESULTS: PSC was diagnosed in 50 patients in four different tertiary hospitals in Korea. Of them, 18 patients (36.0%) had UC-PSC and 32 patients (64.0%) had PSC alone. The median age at PSC diagnosis was younger in the UC-PSC group than that in the PSC alone group (37 vs. 54 years, P = 0.002). In multivariate analysis, older age at PSC diagnosis (P = 0.007; odds ratio [OR], 0.884; 95% confidence interval [CI], 0.808-0.966) and current smoking habit (P = 0.033; OR, 0.026; 95% CI, 0.001-0.748) were determined to be independent factors for reducing the possibility of developing concomitant UC after PSC. Additionally, UC-PSC was shown to be an independent risk factor for the development of colorectal dysplasia (P = 0.044; OR, 10.829; 95% CI, 1.065-110.127). CONCLUSIONS: Our analysis showed that UC-PSC is more likely to be negatively associated with current smoking and older age at the time of PSC diagnosis. Moreover, UC-PSC increased the risk of colorectal dysplasia.

Double amplified colorimetric detection of DNA using gold nanoparticles, enzymes and a catalytic hairpin assembly.

The authors describe an isothermal and ultrasensitive colorimetric DNA assay that consists of two amplification stages using enzymes and a catalytic hairpin assembly (CHA). The first step consists in the selective amplification of DNA using Klenow fragment and nicking enzyme. The second step consists in the amplification of the optical signal by using a catalytic hairpin assembly. After two amplification steps, the DNA reaction induces the aggregation of the red gold nanoparticles to give a blue color shift. The degree of aggregation can be quantified by measurement of the ratio of the UV-vis absorbances of the solutions at 620 and 524 nm which are the wavelengths of the aggregated gold nanoparticles and bare gold nanoparticles. The detection limit is as low as 3.1 fM. Due to the use of a specific enzyme, only the desired DNAs will be detected. The method can be applied to the determination of DNA of various lengths. Despite the presence of large amounts of wildtype DNA, it can readily detect a target DNA. Conceivably, the technique has a large potential because of its high sensitivity and selectivity. Graphical abstract Schematic presentation of DNA detection using gold nanoparticles (AuNP), enzymes and catalytic hairpin assembly (CHA). Effective DNA detection is achieved through the aggregation of AuNPs which is caused by DNA amplification using enzymes and signal amplification using CHA.