Evaluating Free Thermal Expansion and Glass Transition of Ultrathin Polymer Films on Heated Liquid.

Thermomechanical properties of ultrathin films are crucial for fabrication and use of reliable thin electronic devices. Due to the lack of precise measurement techniques, the thermal deformation behavior of ultrathin films has not yet been clarified. Here, we propose a film on heated liquid (FOHL) method to simultaneously measure the coefficient of thermal expansion (CTE) and glass transition temperature (Tg) of multiple ultrathin polymer films. Free thermal expansion of thin films without substrate interaction can be guaranteed when the thin films are afloat on a liquid surface. To investigate the thermal behavior in a wide temperature range, glycerol is adopted as a thermally stable heating platform owing to its high boiling point of 290 °C. The thin films are transferred onto the glycerol surface from the water surface using the hygroscopic properties of glycerol. Highly accurate and high-throughput thermal strain measurement is achieved using three-dimensional digital image correlation (3D-DIC). The thermomechanical properties of ultrathin polystyrene thin films of various thicknesses (25-400 nm) are precisely characterized utilizing the FOHL and 3D-DIC method.

Delay in the diagnosis of Brucella abortus bacteremia in a nonendemic country: a case report.

BACKGROUND: It is challenging to diagnose brucellosis in nonendemic regions because it is a nonspecific febrile disease. The accurate identification of Brucella spp. in clinical microbiology laboratories (CMLs) continues to pose difficulties. Most reports of misidentification are for B. melitensis, and we report a rare case of misidentified B. abortus. CASE PRESENTATION: A 67-year-old man visited an outpatient clinic complaining of fatigue, fever, and weight loss. The patient had a history of slaughtering cows with brucellosis one year prior, and his Brucella antibody tests were negative twice. After blood culture, the administration of doxycycline and rifampin was initiated. The patient was hospitalized due to a positive blood culture. Gram-negative coccobacilli were detected in aerobic blood culture bottles, but the CML's lack of experience with Brucella prevented appropriate further testing. Inaccurate identification results were obtained for a GN ID card of VITEK 2 (bioMérieux, USA) and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) using a MALDI Biotyper (Bruker, Germany). The strain showed 100.0% identity with Brucella spp. according to 16S rRNA sequencing. MALDI-TOF MS peaks were reanalyzed using the CDC MicrobeNet database to determine Brucella spp. (score value: 2.023). The patient was discharged after nine days of hospitalization and improved after maintaining only doxycycline for six weeks. The isolate was also identified as Brucella abortus by genomic evidence. CONCLUSION: Automated identification instruments and MALDI-TOF MS are widely used to identify bacteria in CMLs, but there are limitations in accurately identifying Brucella spp. It is important for CMLs to be aware of the possibility of brucellosis through communication with clinicians. Performing an analysis with an additional well-curated MALDI-TOF MS database such as Bruker security-relevant (SR) database or CDC MicrobeNet database is helpful for quickly identifying the genus Brucella.

Plane Stress Fracture Toughness Testing of Freestanding Ultra-Thin Nanocrystalline Gold Films on Water Surface.

Fracture toughness, which is the resistance of a material to crack propagation, is a critical material property for ensuring the mechanical reliability of damage-tolerant design. Recently, damage-tolerant design is introduced to flexible electronics by adopting micro-cracked ultra-thin nanocrystalline (NC) gold films as stretchable electrodes in a plane stress state. However, experimental investigation of the plane stress fracture toughness of those films remains challenging due to the intrinsic fragility from their sub-100 nm thicknesses. Here, a quantitative method for systematically evaluating the plane stress fracture toughness of freestanding ultra-thin NC gold film on water surface platform is presented. After effectively fabricating single-edge-notched-tension samples with femtosecond laser, mode I stress intensity factors are measured in the plane stress state on water surface. Moreover, investigation regarding the effect of notch length, notch sharpness, and notch tip plasticity validates this method based on linear elastic fracture mechanics theory. As a demonstration, the thickness-dependent plane stress fracture toughness of ultra-thin NC gold films is qualitatively unveiled. It is revealed that the thickness confinement effect on grain boundary sliding induces a transition in fracture behavior. This method is expected to further clarify the fracture-related properties of various ultra-thin films for next-generation electronics.

Advancing Breathability of Respiratory Nanofilter by Optimizing Pore Structure and Alignment in Nanofiber Networks.

Respiratory masks are the primary and most effective means of protecting individuals from airborne hazards such as droplets and particulate matter during public engagements. However, conventional electrostatically charged melt-blown microfiber masks typically require thick and dense membranes to achieve high filtration efficiency, which in turn cause a significant pressure drop and reduce breathability. In this study, we have developed a multielectrospinning system to address this issue by manipulating the pore structure of nanofiber networks, including the use of uniaxially aligned nanofibers created via an electric-field-guided electrospinning apparatus. In contrast to the common randomly collected microfiber membranes, partially aligned dual-nanofiber membranes, which are fabricated via electrospinning of a random 150 nm nanofiber base layer and a uniaxially aligned 450 nm nanofiber spacer layer on a roll-to-roll collector, offer an efficient way to modulate nanofiber membrane pore structures. Notably, the dual-nanofiber configuration with submicron pore structure exhibits increased fiber density and decreased volume density, resulting in an enhanced filtration efficiency of over 97% and a 50% reduction in pressure drop. This leads to the highest quality factor of 0.0781. Moreover, the submicron pore structure within the nanofiber networks introduces an additional sieving filtration mechanism, ensuring superior filtration efficiency under highly humid conditions and even after washing with a 70% ethanol solution. The nanofiber mask provides a sustainable solution for safeguarding the human respiratory system, as it effectively filters and inactivates human coronaviruses while utilizing 130 times fewer polymeric materials than melt-blown filters. This reusability of our filters and their minimum usage of polymeric materials would significantly reduce plastic waste for a sustainable global society.

Genetic stability of Mycobacterium abscessus during antibiotic treatment.

OBJECTIVES: Genetic changes in Mycobacterium abscessus during antibiotic treatment are not fully understood. This study aimed to investigate the genetic changes in M. abscessus in patients receiving antibiotic treatment, and their clinical implications. METHODS: Pretreatment and 12-month post-treatment M. abscessus isolates were obtained from patients with M. abscessus pulmonary disease. Isolates from each time point were separated into six groups based on their distinctive morphological characteristics. Twenty-four isolates, comprising 12 from patient A exhibiting progressive disease and 12 from patient B demonstrating stable disease, underwent sequencing. Subsequently, minimal inhibitory concentrations (MICs) for the administered antibiotics were measured. RESULTS: Persistent infection with a single strain was observed in patients A and B. During 12 months of treatment, MICs for administered drugs did not generally change over time in either patient and single nucleotide variations (SNV) associated with antimicrobial resistance (rrl, rrs, erm(41), gyrA, gyrB, whiB7 and hflX) were not mutated. Although not significant, 47 and 52 non-synonymous SNVs occurred in M. abscessus from patients A and B, respectively, and the accumulation of these SNVs differed in patients A and B, except for five SNVs. The most variable positions were within a probable NADH-dependent glutamate synthase gene and a putative YrbE family protein gene in patients A and B, respectively. CONCLUSIONS: Persistent infections by a single strain of M. abscessus were observed in two patients with different clinical courses. Genetic changes in M. abscessus during antibiotic treatment were relatively stable in these patients. CLINICAL TRIALS IDENTIFIER: NCT01616745 (ClinicalTrials.gov ID).

Integration of Large-Area Halide Perovskite Single Crystals and Substrates via Chemical Welding Using an Ionic Liquid for Applications in X-ray Detection.

The large carrier lifetime mobility product and strong stopping power for high-energy X-rays make halide perovskites an attractive candidate for next-generation X-ray detectors. In particular, high-energy X-rays in the range of several tens of keV require halide perovskite absorber layers with thicknesses exceeding a few millimeters. To avoid carrier scattering caused by grain boundaries at such thicknesses, the utilization of single crystals is desirable. Large-area single crystals are predominantly grown in a freestanding form, and integration onto a substrate is necessary for the fabrication of commercial devices. However, an effective method for integrating large single crystals onto a substrate has not yet been developed. In this study, a large-area (20 cm2) MAPbBr3 single crystal is bonded to an indium tin oxide (ITO) substrate using an ionic liquid, showing strong adhesion strength of 164 kPa. X-ray detectors based on ITO/MAPbBr3 single crystal bonded by methylammonium acetate achieved excellent sensitivity of 91,200 µC Gyair-1 cm-2, the highest among substrate-integrated halide perovskite single crystal X-ray detectors.

Universal selective transfer printing via micro-vacuum force.

Transfer printing of inorganic thin-film semiconductors has attracted considerable attention to realize high-performance soft electronics on unusual substrates. However, conventional transfer technologies including elastomeric transfer printing, laser-assisted transfer, and electrostatic transfer still have challenging issues such as stamp reusability, additional adhesives, and device damage. Here, a micro-vacuum assisted selective transfer is reported to assemble micro-sized inorganic semiconductors onto unconventional substrates. 20 µm-sized micro-hole arrays are formed via laser-induced etching technology on a glass substrate. The vacuum controllable module, consisting of a laser-drilled glass and hard-polydimethylsiloxane micro-channels, enables selective modulation of micro-vacuum suction force on microchip arrays. Ultrahigh adhesion switchability of 3.364 × 106, accomplished by pressure control during the micro-vacuum transfer procedure, facilitates the pick-up and release of thin-film semiconductors without additional adhesives and chip damage. Heterogeneous integration of III-V materials and silicon is demonstrated by assembling microchips with diverse shapes and sizes from different mother wafers on the same plane. Multiple selective transfers are implemented by independent pressure control of two separate vacuum channels with a high transfer yield of 98.06%. Finally, flexible micro light-emitting diodes and transistors with uniform electrical/optical properties are fabricated via micro-vacuum assisted selective transfer.

Prosthetic valve endocarditis caused by Campylobacter fetus: a case report and literature review.

Campylobacter fetus is a Gram-negative bacillus typically associated with bacteremia in immunocompromised patients. Prosthetic valve endocarditis (PVE) is a serious complication of prosthetic valve surgery, with a high mortality rate if not treated promptly. We present a rare case of PVE caused by C. fetus. A man in his mid-60s presented to the Emergency Department with a fever and showed elevated C-reactive protein concentrations. He had prosthetic mitral and aortic valve replacement surgery 15 years previously. Gram-negative rods were detected in a blood culture. These rods were identified as C. fetus using matrix-assisted laser desorption ionization time-of-flight mass spectrometry and confirmed by 16S rRNA sequencing. The patient was treated with gentamicin and imipenem, and underwent valve replacement surgery. C. fetus was isolated in a left atrial appendage swab obtained during the surgery. Follow-up blood cultures were negative after treatment. However, after a cardiac arrest event, the patient's general condition deteriorated, and he died. To the best of our knowledge, this is the first case of PVE caused by C. fetus in Korea and the second fatality to date. This case highlights the importance of considering C. fetus as a potential cause of PVE, even in patients without known risk factors.

First Detection of Enterovirus D68 in Korean Children, September 2022.

BACKGROUND: Enterovirus D68 (EV-D68) is a re-emerging pathogen that is particularly common in children and may cause asthma-like respiratory infection and acute flaccid myelitis. However, in Korea, EV-D68 has never been reported thus far. This study aimed to identify EV-D68 from nasopharyngeal aspirates (NPAs) in Korean children with a respiratory tract infection. MATERIALS AND METHODS: The EV-D68 reference strain was purchased and blindly used to assess the detection ability of three commercial and one in-house mRT-PCR kit in 2018. Then, we selected children whose specimens were positive for human rhinovirus (HRV) and/or enterovirus (EV) by Allplex mRT-PCR (Seegene, Inc., Seoul, Korea) from April to December 2022. Total RNA was extracted from NPAs, and a partial 5'-UTR gene was amplified and sequenced for the identification of HRV/EV species. Additionally, PCR targeting the VP1 gene was performed to assess EV-D68-positive NPAs, followed by sequencing. Phylogenetic analysis and comparison of amino acid sequence alignments were performed using a partial VP1 gene of our and recent international EV-D68 strains. RESULTS: Among the mRT-PCR kits tested, only the in-house kit was able to detect EV-D68 in 2018. However, we detected three EV-D68 strains among children hospitalized with fever and/or respiratory symptoms in September - December 2022 who tested positive for EV by the Allplex kit. Two of them were healthy toddlers with lower respiratory infections accompanied by new-onset wheezing but no neurologic complications. Among 34 children with lower respiratory infection who tested positive for HRV during the same period, EV-D68 was not detected. Phylogenetic analysis revealed that the first Korean EV-D68 belonged to subclade B3. Amino acid sequence alignment of international subclade B3 EV-D68 strains also showed that our strain is genetically more related to those from Europe than those from Japan. CONCLUSION: We first detected EV-D68 in three Korean children who had EV detected by the Allplex mRT-PCR kit in 2022. EV-D68 also circulated in Korea in fall 2022, but the prevalence and severity seemed to be lower than those in previous reports from other countries.

Study of mechanical degradation of freestanding ALD Al2O3 by a hygrothermal environment and a facile protective method for environmentally stable Al2O3: toward highly reliable wearable OLEDs.

Al2O3 deposited via atomic layer deposition (ALD) has been used as an insulating and barrier film for thin-film transistors, organic electronics, and microelectromechanical systems. However, ALD Al2O3 films are easily degraded by hydrolysis under harsh hygrothermal conditions, owing to their poor environmental stability. In this study, the mechanical properties and water-vapor transmission rate (WVTR) of environmentally degraded Al2O3 films were investigated by varying the temperature and relative humidity (RH). The hygrothermal environment led to surface and pinhole-concentrated degradation based on aluminum hydroxide, which caused an increased WVTR and reduced elongation of the films in harsher environments. In particular, the elongation of the degraded Al2O3 films was reduced to 0.3%, which is one-third of that of as-deposited Al2O3, and their WVTR increased on the order of 10-1 g m-2 day-1, which is more than 1000 times that of as-deposited Al2O3. Therefore, we introduced a functional silane-based inorganic-organic hybrid layer (silamer) onto the Al2O3 films to improve their environmental stability. The silamer helped preserve the characteristics of Al2O3 films by forming a strong and continuous aluminate phase of Al-O-Si at their interface in hygrothermal environments. Furthermore, the silamer-capped Al2O3 was shown to be an environmentally stable encapsulation for application in wearable organic devices.

Reducing Bonding Temperature and Energy Consumption in Electronic Packaging Using Flash Electro-Thermal Carbon Fiber Heating Elements.

Semiconductor packaging based on an epoxy molding compound (EMC) currently has several disadvantages including warpage, limited processing area, and variability that all negatively affect cost and production yield. We propose a facile EMC molding process method using a flash electro-thermal carbon fiber heating (FE-CH) device based on carbon fiber-based papers to manufacture an EMC molded to a copper substrate (EMC/Cu bi-layer package) via Joule heating, and using this device, a modified cure cycle that combines the conventional cure cycle (CCC) with rapid cooling was performed using FE-CH to reduce the curvature of the EMC/Cu bi-layer package. Compared to the conventional hot press process, which uses 3.17 MW of power, the FE-CH process only uses 32.87 kW, resulting in a power consumption reduction of over 100 times when following the CCC. Furthermore, the FE-CH-cured EMC/Cu bi-layer package exhibits mechanical properties equivalent to those of a hot press-cured specimen, including the degree of cure, elastic modulus, curvature, bonding temperature, residual strain, and peel strength. The modified cure cycle using the FE-CH results in a 31% reduction in residual strain, a 32% reduction in curvature, and a 47% increase in peel strength compared to the CCC, indicating that this new process method is very promising for reducing a semiconductor package's price by reducing the process cost and warpage.

Microbiological Cure at Treatment Completion Is Associated With Longer Survival in Patients With Mycobacterium avium Complex Pulmonary Disease.

BACKGROUND: Morbidity and mortality from nontuberculous mycobacterial pulmonary disease (NTM-PD) are increasing. Mycobacterium avium complex (MAC) is the most common cause of NTM-PD. Microbiological outcomes are widely used as the primary end point of antimicrobial treatment, but their long-term impact on prognosis is uncertain. RESEARCH QUESTION: Do patients who achieve microbiological cure at the end of treatment have longer survival than those who do not? STUDY DESIGN AND METHODS: We retrospectively analyzed adult patients who met the diagnostic criteria for NTM-PD, were infected with MAC species, and were treated with a macrolide-based regimen for ≥ 12 months per guidelines between January 2008 and May 2021 at a tertiary referral center. Mycobacterial culture was performed during antimicrobial treatment to assess the microbiological outcome. Patients with three or more consecutive negative cultures collected ≥ 4 weeks apart and no positive cultures until treatment completion were considered to have achieved microbiological cure. To assess the impact of microbiological cure on all-cause mortality, we performed multivariable Cox proportional hazards regression analysis adjusted for age, sex, BMI, presence of cavitary lesions, erythrocyte sedimentation rate, and underlying comorbid conditions. RESULTS: Among 382 patients enrolled, 236 (61.8%) achieved microbiological cure at completion of treatment. These patients were younger, had lower erythrocyte sedimentation rates, were less likely to use four or more drugs, and had shorter treatment duration than those who failed to achieve microbiological cure. During a median follow-up of 3.2 (first quartile to third quartile, 1.4-5.4) years after treatment completion, 53 patients died. Microbiological cure was significantly associated with reduced mortality after adjustment for major clinical factors (adjusted hazard ratio, 0.52; 95% CI, 0.28-0.94). The association between microbiological cure and mortality was maintained in a sensitivity analysis that included all patients treated < 12 months. INTERPRETATION: Microbiological cure at completion of treatment is associated with longer survival in patients with MAC-PD.

Porous Material (Titanium Gas Diffusion Layer) in Proton Exchange Membrane Fuel Cell/Electrolyzer: Fabrication Methods & GeoDict: A Critical Review.

Proton exchange membrane fuel cell (PEMFC) is a renewable energy source rapidly approaching commercial viability. The performance is significantly affected by the transfer of fluid, charges, and heat; gas diffusion layer (GDL) is primarily concerned with the consistent transfer of these components, which are heavily influenced by the material and design. High-efficiency GDL must have excellent thermal conductivity, electrical conductivity, permeability, corrosion resistance, and high mechanical characteristics. The first step in creating a high-performance GDL is selecting the appropriate material. Therefore, titanium is a suitable substitute for steel or carbon due to its high strength-to-weight and superior corrosion resistance. The second crucial parameter is the fabrication method that governs all the properties. This review seeks to comprehend numerous fabrication methods such as tape casting, 3D printing, freeze casting, phase separation technique, and lithography, along with the porosity controller in each process such as partial sintering, input design, ice structure, pore agent, etching time, and mask width. Moreover, other GDL properties are being studied, including microstructure and morphology. In the future, GeoDict simulation is highly recommended for optimizing various GDL properties, as it is frequently used for other porous materials. The approach can save time and energy compared to intensive experimental work.

Experimental and Computational Study of Optimized Gas Diffusion Layer for Polymer Electrolyte Membrane Electrolyzer.

Polymer electrolyte membrane fuel cells (PEMFCs) and PEM electrolyzer are emerging technologies that produce energy with zero carbon emissions. However, the commercial feasibility of these technologies mostly relies on their efficiency, which is determined by individual parts, including the gas diffusion layer (GDL). GDL transfers fluid and charges while protecting other components form flooding and corrosion. As there is a very limited attention toward the simulation work, in this work, a novel approach was utilized that combines simulation and experimental techniques to optimize the sintering temperature of GDL. Ti64 GDL was produced through tape casting, a commercial method famous for producing precise thickness, uniform, and high-quality films and parameters such as slurry composition and rheology, casting parameters, drying, and debinding were optimized. The porosity and mechanical properties of the samples were tested experimentally at various sintering temperatures. The experimental results were compared with the simulated results achieved from the GeoDict simulation tool, showing around 96% accuracy, indicating that employing GeoDict to optimize the properties of Ti64 GDL produced via tape casting is a critical step towards the commercial feasibility of PEMFCs and electrolyzer. These findings significantly contribute to the development of sustainable energy solutions.

Quantum Dot-Siloxane Anchoring on Colloidal Quantum Dot Film for Flexible Photovoltaic Cell.

Lead sulfide (PbS) colloidal quantum dots (CQDs) are promising materials for next-generation flexible solar cells because of near-infrared absorption, facile bandgap tunability, and superior air stability. However, CQD devices still lack enough flexibility to be applied to wearable devices owing to the poor mechanical properties of CQD films. In this study, a facile approach is proposed to improve the mechanical stability of CQDs solar cells without compromising the high power conversion efficiency (PCE) of the devices. (3-aminopropyl)triethoxysilane (APTS) is introduced on CQD films to strengthen the dot-to-dot bonding via QD-siloxane anchoring, and as a result, crack pattern analysis reveals that the treated devices become robust to mechanical stress. The device maintains 88% of the initial PCE under 12 000 cycles at a bending radius of 8.3 mm. In addition, APTS forms a dipole layer on CQD films, which improves the open circuit voltage (VOC ) of the device, achieving a PCE of 11.04%, one of the highest PCEs in flexible PbS CQD solar cells.

Effect of Wearing Personal Protective Equipment (PPE) for COVID-19 Treatment on Blood Culture Contamination: Implication for Optimal PPE Strategies.

The personal protective equipment (PPE) used to minimize exposure to hazards can hinder healthcare workers from performing sophisticated procedures. We retrospectively reviewed 77,535 blood cultures (202,012 pairs) performed in 28,502 patients from January 2020 to April 2022. The contamination rate of all blood cultures was significantly elevated in the coronavirus disease 2019 ward at 4.68%, compared to intensive care units at 2.56%, emergency rooms at 1.13%, hematology wards at 1.08%, and general wards at 1.07% (All of P < 0.001). This finding implies that wearing PPE might interfere with adherence to the aseptic technique. Therefore, a new PPE policy is needed that considers the balance between protecting healthcare workers and medical practices.

Adjusted Bulk and Interfacial Properties in Highly Stable Semitransparent Perovskite Solar Cells Fabricated by Thermocompression Bonding between Perovskite Layers.

In order to shield perovskite solar cells (PSCs) from extrinsic degradation factors and ensure long-term stability, effective encapsulation technology is indispensable. Here, a facile process is developed to create a glass-glass encapsulated semitransparent PSC using thermocompression bonding. From quantifying the interfacial adhesion energy and considering the power conversion efficiency of devices, it is confirmed that bonding between perovskite layers formed on a hole transport layer (HTL)/indium-doped tin oxide (ITO) glass and an electron transport layer (ETL)/ITO glass can offer an excellent lamination method. The PSCs fabricated through this process have only buried interfaces between the perovskite layer and both charge transport layers as the perovskite surface is transformed into bulk. The thermocompression process leads the perovskite to have larger grains and smoother, denser interfaces, thereby not only reducing defect and trap density but also suppressing ion migration and phase segregation under illumination. In addition, the laminated perovskite demonstrates enhanced stability against water. The self-encapsulated semitransparent PSCs with a wide-band-gap perovskite (Eg ∼ 1.67 eV) demonstrate a power conversion efficiency of 17.24% and maintain long-term stability with PCE > ∼90% in the 85 °C shelf test for over 3000 h and with PCE > ∼95% under AM 1.5 G, 1-sun illumination in an ambient atmosphere for over 600 h.

High-Performance Intrinsically Stretchable Polymer Solar Cell with Record Efficiency and Stretchability Enabled by Thymine-Functionalized Terpolymer.

Designing new polymer semiconductors for intrinsically stretchable polymer solar cells (IS-PSCs) with high power conversion efficiency (PCE) and durability is critical for wearable electronics applications. Nearly all high-performance PSCs are constructed using fully conjugated polymer donors (PD) and small-molecule acceptors (SMA). However, a successful molecular design of PDs for high-performance and mechanically durable IS-PSCs without sacrificing conjugation has not been realized. In this study, we design a novel thymine side chain terminated 6,7-difluoro-quinoxaline (Q-Thy) monomer and synthesize a series of fully conjugated PDs (PM7-Thy5, PM7-Thy10, PM7-Thy20) featuring Q-Thy. The Q-Thy units capable of inducing dimerizable hydrogen bonding enable strong intermolecular PD assembly and highly efficient and mechanically robust PSCs. The PM7-Thy10:SMA blend demonstrates a combination of high PCE (>17%) in rigid devices and excellent stretchability (crack-onset value >13.5%). More importantly, PM7-Thy10-based IS-PSCs show an unprecedented combination of PCE (13.7%) and ultrahigh mechanical durability (maintaining 80% of initial PCE after 43% strain), illustrating the promising potential for commercialization in wearable applications.