Association between prophylactic closure of mucosal defect and delayed adverse events after endoscopic resection: a systematic review and meta-analysis.

OBJECTIVE: To investigate the potential of prophylactic closure of mucosal defects to prevent adverse events following endoscopic resection of superficial layers of the gastrointestinal (GI) wall. DESIGN: Systematic review and meta-analysis. DATA SOURCES: We searched PubMed, Embase, Web of Science and the Cochrane Library for studies eligible for inclusion in our meta-analysis from inception to February 2022. DATA EXTRACTION AND SYNTHESIS: We compared the effects of closure versus non-closure of mucosal defects with respect to adverse events including delayed bleeding, delayed perforation and postpolypectomy coagulation syndrome (PPCS). We used a random-effects model for all analyses. Subgroup analyses were performed based on gastrointestinal sites, surgical procedures and study designs. RESULTS: In total, this study includes 11 383 patients from 28 studies. For delayed bleeding, closure group was associated with a lower incidence (Risk Ratio [RR]: 0.40, 95% Confidence interval [CI]: 0.30 to 0.53, p<0.001; I2=25%) and consistent results were observed in the subgroups. Also, for delayed perforation, a combined analysis of all sites and surgical methods showed a protective effect of prophylactic closure of mucosal defects (RR: 0.42, 95% CI: 0.22 to 0.82, p=0.01; I2=0%). Similar results were observed in the subgroup analyses, despite the wide CIs. Regarding the PPCS, neither the pooled RRs nor the subgroup analyses showed significant differences. CONCLUSION: Prophylactic closure of mucosal defects is beneficial in reducing the incidence of delayed bleeding and delayed perforation after endoscopic resection, but there is no significant difference in reducing the incidence of PPCS.

Expression of concern: Surface modification engineering of two-dimensional titanium carbide for efficient synergistic multitherapy of breast cancer.

Expression of concern for 'Surface modification engineering of two-dimensional titanium carbide for efficient synergistic multitherapy of breast cancer' by Lei Bai et al., J. Mater. Chem. B, 2020, 8, 6402-6417, https://doi.org/10.1039/D0TB01084G.

Gastric residual volume, safety, and effectiveness of drinking 250 mL of glucose solution 2-3 hours before surgery in gastric cancer patients: a multicenter, single-blind, randomized-controlled trial.

Background: Carbohydrate drinking 2-3 hours before surgery has been widely adopted in colorectal operations. However, there is little direct evidence regarding its application in gastric cancer surgery. We aimed to evaluate the gastric residual volume, safety, and effectiveness of drinking 250 mL of 5% glucose solution 2-3 hours before elective gastric cancer surgery. Methods: We conducted an investigator-initiated, multicenter, randomized-controlled, parallel group, and equivalence trial. Eighty-eight patients with gastric adenocarcinoma were randomized into study or control group. Patients in the control group followed the traditional routine of 6-8 hours preoperative fasting, while those in the study group drank 250 mL of 5% glucose solution 2-3 hours before surgery. Immediately following tracheal intubation, gastric contents were aspirated through gastroscopy. The primary outcome was preoperative gastric residual volume. Results: Eighty-three patients were eventually analysed in the study (42 in the study group and 41 in the control group). Two groups were comparable at baseline characteristics. There were no statistical differences in residual gastric fluid volumes (35.86 ± 27.13 vs 27.70 ± 20.37 mL, P = 0.135) and pH values (2.81 ± 1.99 vs 2.66 ± 1.68, P = 0.708) between the two groups. Preoperative discomfort was significantly more decreased in the study group than in the control group (thirst score: 1.49 ± 1.23 vs 4.14 ± 2.07, P < 0.001; hunger score: 1.66 ± 1.18 vs 3.00 ± 2.32, P = 0.007). There was no statistical difference in the incidence of postoperative complications (19.05% vs 17.07%, P = 0.815). Conclusions: Drinking 250 mL of 5% glucose solution 2-3 hours before surgery in elective gastric cancer patients shows benefits in lowering thirst and hunger scores without increasing gastric residual volume and perioperative complications.

Fiber Bragg gratings fabricated in fibers with different geometries by femtosecond laser written through the coating and their applications in strain sensing and fiber laser.

Applications of the type-I fiber Bragg gratings (FBGs) written through the coating (TTC) in strain sensing and tunable distributed Bragg reflector (DBR) fiber lasers were demonstrated. We reported the principle of selecting the distance between the fiber and the phase mask when writing type-I TTC FBGs. Type-I TTC FBGs written in commercially available acrylate-coated fibers with various geometries and their strain responses were demonstrated. Results showed that the strain sensitivity of FBGs increases as the core-diameter decreases, probably due to the waveguide effect. In addition, a continuously tunable DBR fiber laser based on TTC FBGs was achieved with a wavelength tuning range of 19.934 nm around 1080 nm, by applying a strain of 0-21265.8 µÉ› to the laser resonant cavity. The wavelength tuning range was limited by the splice point between the gain fiber and the passive fiber for transmitting pump and signal lasers. When the pump power was 100 mW, the relative intensity noises were -97.334 dB/Hz at the relaxation oscillation peak of 880 kHz and -128 dB/Hz at frequencies greater than 3 MHz. The results open a potential scheme to design and implement continuously tunable fiber lasers and fiber laser sensors for strain sensing with a higher resolution.

Photoinduced carrier transfer dynamics in a monolayer MoS2/PbS quantum dots heterostructure.

Two-dimensional molybdenum disulfide (MoS2) has been proven to be a candidate in photodetectors, and MoS2/lead sulfide (PbS) quantum dots (QDs) heterostructure has been used to expand the optical response wavelength of MoS2. Time-resolved pump-probe transient absorption measurements are performed to clarify the carrier transfer dynamics in the MoS2/PbS heterostructure. By comparing the carrier dynamics in MoS2 and MoS2/PbS under different pump wavelengths, we found that the excited electrons in PbS QDs can transfer rapidly (<100 fs) to MoS2, inducing its optical response in the near-infrared region, although the pump light energy is lower than the bandgap of MoS2. Besides, interfacial excitons can be formed in the heterostructure, prolonging the lifetime of the excited carriers, which could be beneficial for the extraction of the carriers in devices.

Femtosecond Laser Fabrication of High-Linearity Liquid Metal-Based Flexible Strain Sensor.

Liquid metal (LM) is widely used in flexible electronic devices due to its excellent metallic conductivity and ductility. However, the fabrication of LM flexible strain sensors with high sensitivity and linearity is still a huge challenge, since the resistance of LM does not change much with strain. Here, a highly sensitive and linear fully flexible strain sensor with a resistive sensing function is proposed. The sensor comprises an Fe-doped liquid metal (Fe-LM) electrode for enhanced performance. The design and manufacturing of flexible strain sensors are based on the technology of controlling surface wettability by femtosecond laser micro/nano-processing. A supermetalphobic microstructure is constructed on a polydimethylsiloxane (PDMS) substrate to achieve the selection adhesion of Fe-LM on the PDMS substrate. The Fe-LM-based flexible strain sensor has high sensitivity and linearity, a gauge factor (GF) up to 1.18 in the strain range of 0-100%, excellent linearity with an R2 of 0.9978, a fast response time of 358 ms, and an excellent durability of more than 2400 load cycles. Additionally, the successful monitoring of human body signals demonstrates the potential of our developed flexible strain sensor in wearable monitoring applications.

Exceptional Stability against Water, UV Light, and Heat for CsPbBr3@Pb-MOF Composites.

All-inorganic lead halide perovskite nanocrystals (NCs) have been widely applied in optoelectronic devices owing to their excellent photoluminescence (PL) properties. However, poor stability upon exposure to water, UV light or heat strongly limits their practical application. Herein, CsPbBr3@Pb-MOF composites with exceptional stability against water, UV light, and heat are synthesized by ultrasonic processing the precursors of lead-based MOF (Pb-MOF), oleylammonium bromide (OAmBr) and cesium oleate (Cs-OA) solutions at room temperature. Pb-MOF can not only provide the lead source for the in situ growth of CsPbBr3 NCs, but also the protective layer of perovskites NCs. The formed CsPbBr3@Pb-MOF composites show a considerable PL quantum yield (PLQY) of 67.8%, and can maintain 90% of the initial PL intensity when immersed in water for 2 months. In addition, the outstanding PL stability against UV light and heat is demonstrated with CsPbBr3 NCs synthesized by the conventional method as a comparison. Finally, a green (light-emitting diode) LED is fabricated using green-emitting CsPbBr3@Pb-MOF composites and exhibits excellent stability without packaging when immersed in water for 30 days. This study provides a practical approach to improve the stability in aqueous phase, which may pave the way for future applications for various optoelectronic devices.

Linewidth compression of a single longitudinal mode ytterbium-doped fiber laser based on femtosecond laser fabricated fiber Bragg gratings.

We demonstrate a single longitudinal mode distributed Bragg reflection (DBR) fiber laser by directly fabricating fiber Bragg gratings (FBGs) on an ytterbium-doped fiber (YDF) using a femtosecond laser. A simple optical self-injection feedback method was used to effectively compress the linewidth and reduce relative intensity noise (RIN) of a single longitudinal mode DBR fiber laser. Further, we investigated the effect of self-injection feedback cavity length and reflectivity on linewidth compression and determined that the linewidth tends to decrease with the increase of the external cavity photon lifetime. By a self-injection feedback, the laser linewidth was compressed from 31.8 kHz to 1.4 kHz. Meanwhile, the relaxation oscillation peak from -103.2d B/H z at 1.51 MHz was suppressed to -122.3d B/H z at 0.16 MHz. This low-noise narrow linewidth single longitudinal mode fiber laser is expected to be a promising candidate for applications such as active detection of neutral atmosphere and distributed fiber sensing.

Characterizing amyloid protein conformation with a multi-resonant metasurface based biosensor in the infrared window.

Misfolding of amyloid protein will cause neurodegeneration and trigger conformational disease. The lack of an effective detection approach is a brake on unveiling the mechanism of protein misfolding. We theoretically proposed a novel metasurface-based biosensor for characterizing the protein's conformation. The coupling complementary split ring resonator (cSRR) was engineered to manipulate incident waves in the near-infrared (NIR) and mid-infrared (MIR) windows at the same sensing surface. The cSRRs had the advantages of intensifying the electric field and sharpening the resonance profile, resulting in a highly qualified biosensing performance. In the NIR window, the biolayer's refractive index and thickness change were detected by the dual-wavelength, which resolved into an optogeometrical parameter of the amyloid biolayer. In the MIR window, the resonant wave specifically triggered the rotation-vibration transition of amyloid protein molecules with different conformations, which was shown as the unique Amide I and II bands in the fingerprint spectrum. Thus, our proposed biosensor presented sensitive detection of biolayer and specific identification of constituent molecules. It is helpful to interpret the protein's misfolding behavior on the molecular level by associating the biolayer's structure and the constituent molecule's conformational change.

Underwater dynamic polarization imaging without dependence on the background region.

Active-polarization imaging holds significant promise for achieving clear underwater vision. However, only static targets were considered in previous studies, and a background region was required for image restoration. To address these issues, this study proposes an underwater dynamic polarization imaging method based on image pyramid decomposition and reconstruction. During the decomposition process, the polarized image is downsampled to generate an image pyramid. Subsequently, the spatial distribution of the polarization characteristics of the backscattered light is reconstructed by upsampling, which recovered the clear scene. The proposed method avoids dependence on the background region and is suitable for moving targets with varying polarization properties. The experimental results demonstrate effective elimination of backscattered light while sufficiently preserving the target details. In particular, for dynamic targets, processing times that fulfill practical requirements and yield superior recovery effects are simultaneously obtained.

Sub-diffraction limited nanogroove fabrication of 30 nm features on diamond films using 800 nm femtosecond laser irradiation.

By controlling the 800 nm fs laser energy and applying an isopropyl alcohol environment, controlled sub-diffraction limited lithography with a characteristic structure of approximately 30 nm was achieved on the surface of diamond films, and diamond gratings with a period of 200 nm were fabricated. The fabrication of single grooves with a feature size of 30 nm demonstrates the potential for patterning periodic or nonperiodic structures, and the fabrication of 200 nm periodic grating structures demonstrates the ability of the technique to withstand laser proximity effects. This enhances the technology of diamond film nanofabrication and broadens its potential applications in areas such as optoelectronics and biology.

Energy transfer enhanced photoluminescence of 2D/3D CsPbBr3 hybrid assemblies.

Energy transfer has been proven to be an effective method to optimize optoelectronic conversion efficiency by improving light absorption and mitigating nonradiative losses. We prepared 2D/3D CsPbBr3 hybrid assemblies at different reaction temperatures using the hot injection method and found that the photoluminescence quantum yields (PLQYs) of these hybrids were greatly enhanced from 53.4% to 72.57% compared with 3D nanocrystals (NCs). Femtosecond transient absorption measurements were used to study the PLQY enhancement mechanisms, and it was found that the hot carrier lifetime improved from 0.36 to 1.88 ps for 2D/3D CsPbBr3 hybrid assemblies owing to the energy transfer from 2D nanoplates to 3D NCs. The energy transfer benefits the excited carrier accumulation and prolonged hot carrier lifetime in 3D NCs in hybrid assemblies, as well as PLQY enhancement in materials.

Development and Validation of Serum Markers as Noninvasive Diagnostic Methods for Achalasia.

INTRODUCTION: Currently, the diagnosis of achalasia mainly relies on invasive or radioactive examinations. This study aimed to develop a noninvasive diagnostic method for achalasia based on specific serum markers. METHODS: Serum levels of profilin-1, galectin-10, immunoglobulin heavy variable 3-9, vasodilator-stimulated phosphoprotein, and transgelin-2 were measured in patients with achalasia and controls by enzyme-linked immunosorbent assay. The diagnostic values and thresholds were determined by the receiver operating characteristic curve analysis. Then, patients with dysphagia were prospectively enrolled to validate the ability of these molecules for achalasia diagnosing. RESULTS: A total of 142 patients with achalasia and 50 nonachalasia controls (healthy volunteers and patients with reflux esophagitis) were retrospectively included. The serum levels of profilin-1, galectin-10, and transgelin-2 in patients with achalasia were significantly higher than those in healthy volunteers and patients with reflux esophagitis ( P all < 0.001). Profilin-1, galectin-10, and transgelin-2 were of good performance in diagnosing achalasia, with optimal thresholds of 2,171.2, 33.9, and 1,630.6 pg/mL, respectively. Second, 40 patients with dysphagia were prospectively enrolled to the validation of achalasia. For profilin-1, the positive predictive value, negative predictive value, sensitivity, and specificity were 100.0%, 64.5%, 45.0%, and 100.0%, respectively. The figures for transgelin-2 were 65.5%, 90.9%, 95.0%, and 50.0%. When both increased, the positive predictive value reached to 100.0%. When both indexes were normal, the negative predictive value was 100.0%. DISCUSSION: Profilin-1 and transgelin-2 were promising biomarkers for achalasia diagnosis and performed better in combination. Further multicenter studies are necessary to verify their application as preliminary screening tools for achalasia.

A novel twin-grasper assisted mucosal inverted closure technique for closing large artificial gastric mucosal defects.

BACKGROUND: Large artificial gastric mucosal defects are always left unclosed for natural healing due to technique difficulties in closure. This study aims to evaluate the feasibility and safety of a new Twin-grasper Assisted Mucosal Inverted Closure (TAMIC) technique in closing large artificial gastric mucosal defects. METHODS: Endoscopic submucosal dissection (ESD) was performed in fifteen pigs to create large gastric mucosal defects. The mucosal defects were then either left unclosed or closed with metallic clips using TAMIC technique. Successful closure rate and the wound outcomes were assessed. RESULTS: Two mucosal defects with size of about 4.0 cm were left unclosed and healed two months after surgery. Thirteen large gastric mucosal defects were created by ESD with a medium size of 5.9 cm and were successfully closed with the TAMIC technique (100%), even in a mucosal defect with a width up to 8.5 cm. The mean closure time was 59.0 min. Wounds in eight stomachs remained completely closed 1 week after surgery (61.5%), while closure in the other five stomachs had partial wound dehiscence (38.5%). Four weeks later, all the closed defects healed well and 61.5% of the wounds still remained completely closed during healing. There was no delayed perforation or bleeding after surgery. In addition, there was less granulation in the submucosal layer of the closed wound sites than those under natural healing. CONCLUSIONS: The present study suggests that TAMIC is feasible and safe in closing large artificial gastric mucosal defects and could improve mucosal recovery compared to natural healing process.

Determination of the refractive-index change in the excited state based on transient absorption microscopy.

Photoinduced excited-state carriers can affect both the absorption coefficient and refractive index of materials and influence the performance of photoelectric devices. Femtosecond time-resolved pump-probe transient absorption (TA) spectroscopy is usually used to detect carrier dynamics and excited-state absorption coefficients; however, measurements of transient refractive-index change are still difficult. We propose a method for determining the excited-state refractive-index change using TA microscopy. In TA measurements, a Fabry-Pérot cavity formed by the front and back surfaces of the sample could lead to interference of the probe light. As the wavelength of standing waves in the Fabry-Pérot cavity is closely related to the refractive index, the carrier-induced excited-state refractive-index change was obtained by comparing the transmission probe spectra between the ground and excited states. The proposed method was used to study the dynamics of excited-state refractive-index change in a perovskite film.

Fabrication of a flexible stretchable hydrogel-based antenna using a femtosecond laser for miniaturization.

We demonstrated a new method of fabricating a stretchable antenna by injecting liquid metal (LM) into a femtosecond-laser-ablated embedded hydrogel microchannel, and realized miniaturization of a stretchable dipole antenna based on hydrogel substrate. Firstly, symmetrical microchannels with two equal and linear branches were formed by a femtosecond laser in the middle of a hydrogel substrate, and then were filled with LM by use of a syringe needle. Using this method, a stretchable LM-dipole antenna with each dimension of 24 mm × 0.6 mm × 0.2 mm separated by a 2-mm gap, was formed in the middle of a 70 mm × 12 mm × 7 mm hydrogel slab. Since the polyacrylamide (PAAm) hydrogel contained ∼ 95 wt % deionized water with a high permittivity of 79 in the 0.5 GHz - 1.5 GHz range, the hydrogel used to prepare the flexible antenna can be considered as distilled water boxes. Experiments and simulations showed that a 5-cm-long LM-dipole embedded in hydrogel resonated at approximately 927.5 MHz with an S11 value of about - 12.6 dB and omnidirectional radiation direction. Benefiting from the high permittivity of the hydrogel, the dipole length was downsized by about half compared with conventional polymer substrates at the same resonant frequency. By varying the applied strain from 0 to 48%, the resonant frequency of the hydrogel/LM dipole antenna can be tuned from 770.3 MHz to 927.0 MHz. This method provides a simple and scalable technique for the design and preparation of LM-pattern microstructures in hydrogels, and has potential applications in hydrogel-based soft electronic device.

Visualization of Hot Carrier Dynamics in a Single CsPbBr3 Perovskite Microplate Using Femtosecond Kerr-Gated Wide-Field Fluorescence Spectroscopy.

Lead halide perovskites (LHPs) have excellent semiconductor properties. They have been used in many applications such as solar cells. Recently, the hot carrier dynamics in this type of material have received much attention as they are useful for enhancing the performance of optoelectrical devices fabricated from it. Here, we study the ultrafast hot carrier dynamics of a single CsPbBr3 microplate using femtosecond Kerr-gated wide-field fluorescence spectroscopy. The transient photoluminescence spectra have been measured under a variety of excitation fluences. The temporal evolution of bandgap renormalization and the competition between hot carrier cooling and the recovery of the renormalized bandgap are clearly revealed.

Two-component polymer sorting to obtain high-purity s-SWCNTs for all-carbon photodetectors.

The advancement of carbon-based electronics is reliant on the development of semiconducting carbon nanotubes with high purity and yield. We developed a new extraction strategy to efficiently sort SWCNTs with superior yields and purity. The approach uses two polymers, poly[N-(1-octylnonyl)-9H-carbazol-2,7-diyl](PCz) and poly(9,9-n-dihexyl-2,7-fluorene-alt-9-phenyl-3,6-carbazole)(PDFP), and two sonication processes to eliminate surface polymer contamination. PCz selectively wraps large-diameter s-SWCNTs, with PDFP added as an enhancing molecule to increase sorting efficiency at 4-fold compared to the efficiency of only PCz alone sorting. The purity of the sorted s-SWCNTs was confirmed to be above 99 % using absorption and Raman spectra. Field-effect transistors and photodetectors made from the sorted s-SWCNTs exhibited excellent semiconductor properties and broad-spectrum detection, with good long-term stability. Furthermore, a photodetector using large-tube diameter s-SWCNTs achieved broad-spectrum detection, which the photoresponsivity is 0.35 mA/W and the detectivity is 4.7×106 Jones. The s-SWCNTs/graphene heterojunction photodetector achieved a photoresponsivity of 3 mA/W and a detectivity of 6.3×106 Jones. This new strategy provides a promising approach to obtain high-purity and high-yield s-SWCNTs for carbon-based photodetectors.

High-efficiency dual-layer grating coupler for vertical fiber-chip coupling in two polarizations.

Efficient coupling between optical fibers and high-index-contrast silicon waveguides is essential for the development of integrated nanophotonics. Herein, a high-efficiency dual-layer grating coupler is demonstrated for vertical polarization-diversity fiber-chip coupling. The two waveguide layers are orthogonally distributed and designed for y- and x-polarized L P 01 fiber modes, respectively. Each layer consists of two 1D stacked gratings, allowing for both perfectly vertical coupling and high coupling directionality. The gratings are optimized using the particle swarm algorithm with a preset varying trend of parameters to thin out the optimization variables. The interlayer thickness is determined to ensure efficient coupling of both polarizations. The optimized results exhibit record highs of 92% (-0.38d B) and 85% (-0.72d B) 3D finite-difference time-domain simulation efficiencies for y and x polarizations, respectively. The polarization-dependent loss (PDL) is below 2 dB in a 160 nm spectral bandwidth with cross talk between the two polarizations less than -24d B. Fabrication imperfections are also investigated. Dimensional offsets of ±10n m in etching width and ±8 nm in lateral shift are tolerated for a 1 dB loss penalty. The proposed structure offers an ultimate solution for polarization diversity coupling schemes in silicon photonics with high directionality, low PDL, and a possibility to vertically couple.