Unveiling the distinctive mechanical and thermal properties of γ-GeSe.

γ-GeSe is a newly identified polymorph among group-IV monochalcogenides, characterized by a distinctive interatomic bonding configuration. Despite its promising applications in electrical and thermal domains, the experimental verification of its mechanical and thermal properties remains unreported. Here, we experimentally characterize the in-plane Young's modulus (E) and thermal conductivity ([Formula: see text]) of γ-GeSe. The mechanical vibrational modes of freestanding γ-GeSe flakes are measured using optical interferometry. Nano-indentation via atomic force microscopy is also conducted to induce mechanical deformation and to extract the E. Comparison with finite-element simulations reveals that the E is 97.3[Formula: see text]7.5 GPa as determined by optical interferometry and 109.4[Formula: see text]13.5 GPa as established through the nano-indentation method. Additionally, optothermal Raman spectroscopy reveals that γ-GeSe has a lattice thermal conductivity of 2.3 [Formula: see text] 0.4 Wm-1K-1 and a total thermal conductivity of 7.5 [Formula: see text] 0.4 Wm-1K-1 in the in-plane direction at room temperature. The notably high [Formula: see text] ratio in γ-GeSe, compared to other layered materials, underscores its distinctive structural and dynamic characteristics.

Long-term outcomes of patients with embolic stroke of undetermined source according to subtype.

The prognosis of patients with embolic stroke of undetermined source (ESUS) may vary according to the underlying cause. Therefore, we aimed to divide ESUS into subtypes and assess the long-term outcomes. Consecutive patients with acute ischemic stroke who underwent a comprehensive workup, including transesophageal echocardiography and prolonged electrocardiography monitoring, were enrolled. We classified ESUS into minor cardioembolic (CE) ESUS, arteriogenic ESUS, two or more causes ESUS, and no cause ESUS. Arteriogenic ESUS was sub-classified into complex aortic plaque (CAP) ESUS and non-stenotic (< 50%) relevant artery plaque (NAP) ESUS. A total of 775 patients were enrolled. During 1286 ± 748 days follow-up, 116 major adverse cardiovascular events (MACE) occurred (4.2 events/100 patient-years). Among the ESUS subtypes, CAP ESUS was associated with the highest MACE frequency (9.7/100 patient-years, p = 0.021). Cox regression analyses showed that CAP ESUS was associated with MACE (hazard ratio 2.466, 95% confidence interval 1.305-4.660) and any stroke recurrence (hazard ratio 2.470, 95% confidence interval, 1.108-5.508). The prognosis of ESUS varies according to the subtype, with CAP ESUS having the worst prognosis. Categorizing ESUS into subtypes could improve patient care and refine clinical trials.

Long-term outcome of treatment-naïve patients with mesial temporal lobe epilepsy with hippocampal sclerosis: A retrospective study in a single center.

PURPOSE: This study aimed to describe long-term treatment outcomes of treatment-naïve patients with mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS). METHODS: A retrospective review was conducted of treatment-naïve patients with MTLE-HS who visited the Yonsei Epilepsy Clinic from April 2000 to April 2022 and were followed up for at least 2 years. Seizure freedom (SF) was defined as no seizures or auras only for >1 year, and complete SF was defined as no seizures including auras for >1 year. RESULTS: Eighty-four treatment-naïve patients with MTLE-HS with a median follow-up of 122 months were included. Except for one patient who underwent early surgical treatment, of the remaining 83 patients, 31 (37.3 %) achieved SF and remained in remission, 38 (45.8 %) had fluctuations in seizure control, and 14 (16.9 %) never achieved SF. Additionally, 18 (21.7 %) patients achieved complete SF and remained in remission, 42 (50.6 %) showed fluctuations, and 23 (27.7 %) never achieved complete SF. Fifty-three (63.9 %) patients achieved SF and 34 (41.0 %) achieved complete SF at their last visit. Older age at epilepsy onset, male sex, low pretreatment seizure density, history of central nervous system infection before age 5, absence of aura, and fewer antiseizure medications in the final regimen were associated with favorable outcome. Of the 84 patients, 11 (13.1 %) underwent temporal lobectomy. CONCLUSIONS: Medical treatment outcomes in treatment-naïve MTLE-HS were relatively better than previously reported outcomes in MTLE-HS, although frequent fluctuations in seizure control were observed.

Electrical Transport Properties Driven by Unique Bonding Configuration in γ-GeSe.

Group IV monochalcogenides have recently shown great potential for their thermoelectric, ferroelectric, and other intriguing properties. The electrical properties of group IV monochalcogenides exhibit a strong dependence on the chalcogen type. For example, GeTe exhibits high doping concentration, whereas S/Se-based chalcogenides are semiconductors with sizable bandgaps. Here, we investigate the electrical and thermoelectric properties of γ-GeSe, a recently identified polymorph of GeSe. γ-GeSe exhibits high electrical conductivity (∼106 S/m) and a relatively low Seebeck coefficient (9.4 µV/K at room temperature) owing to its high p-doping level (5 × 1021 cm-3), which is in stark contrast to other known GeSe polymorphs. Elemental analysis and first-principles calculations confirm that the abundant formation of Ge vacancies leads to the high p-doping concentration. The magnetoresistance measurements also reveal weak antilocalization because of spin-orbit coupling in the crystal. Our results demonstrate that γ-GeSe is a unique polymorph in which the modified local bonding configuration leads to substantially different physical properties.

Unveiling Operator Growth Using Spin Correlation Functions.

In this paper, we study non-equilibrium dynamics induced by a sudden quench of strongly correlated Hamiltonians with all-to-all interactions. By relying on a Sachdev-Ye-Kitaev (SYK)-based quench protocol, we show that the time evolution of simple spin-spin correlation functions is highly sensitive to the degree of k-locality of the corresponding operators, once an appropriate set of fundamental fields is identified. By tracking the time-evolution of specific spin-spin correlation functions and their decay, we argue that it is possible to distinguish between operator-hopping and operator growth dynamics; the latter being a hallmark of quantum chaos in many-body quantum systems. Such an observation, in turn, could constitute a promising tool to probe the emergence of chaotic behavior, rather accessible in state-of-the-art quench setups.

γ-GeSe: A New Hexagonal Polymorph from Group IV-VI Monochalcogenides.

The family of group IV-VI monochalcogenides has an atomically puckered layered structure, and their atomic bond configuration suggests the possibility for the realization of various polymorphs. Here, we report the synthesis of the first hexagonal polymorph from the family of group IV-VI monochalcogenides, which is conventionally orthorhombic. Recently predicted four-atomic-thick hexagonal GeSe, so-called γ-GeSe, is synthesized and clearly identified by complementary structural characterizations, including elemental analysis, electron diffraction, high-resolution transmission electron microscopy imaging, and polarized Raman spectroscopy. The electrical and optical measurements indicate that synthesized γ-GeSe exhibits high electrical conductivity of 3 × 105 S/m, which is comparable to those of other two-dimensional layered semimetallic crystals. Moreover, γ-GeSe can be directly grown on h-BN substrates, demonstrating a bottom-up approach for constructing vertical van der Waals heterostructures incorporating γ-GeSe. The newly identified crystal symmetry of γ-GeSe warrants further studies on various physical properties of γ-GeSe.

Toward a disposable low-cost LOC device: heterogeneous polymer micro valve and pump fabricated by UV/ozone-assisted thermal fusion bonding.

Herein, a heterogeneous polymer micro valve and pump with a polypropylene (PP) membrane was developed in a low-cost manner via UV/ozone-assisted thermal fusion bonding. The proposed fabrication technique allowed for a geometrically selective bonding; consequently, the membrane was prevented from bonding with the valve seat of the diaphragm micro-valve, without patterning a protection layer or introducing an additional structure. The developed device withstands 480 kPa of static pressure and up to 350 kPa of a vibration pressure, providing sufficient bonding strength for microfluidic actuations. The fabricated micro valve and pump are fully characterized and compared with a poly(dimethylsiloxane) (PDMS) membrane glass device, showing comparable valving and pumping performance. As a result, the robust PP membrane micro valve and pump are simply implemented in a facile manner, and demonstrated excellent performance, which is highly desirable for mass production of disposable lab-on-a-chip (LOC) devices.

Atrophy patterns in cerebral amyloid angiopathy with and without cortical superficial siderosis.

OBJECTIVE: To investigate differential atrophy patterns based on the presence of cortical superficial siderosis (cSS) and the role of cSS in predicting amyloid positivity in memory clinic patients fulfilling the diagnostic criteria for probable cerebral amyloid angiopathy (CAA). METHODS: We retrospectively collected data from 44 cognitively impaired patients with probable CAA who underwent 3-dimensional, T1-weighted MRIs (cSS+, n = 27; cSS-, n = 17). Amyloid-positive patients with Alzheimer disease (AD) (n = 56) and amyloid-negative cognitively normal participants (n = 34) were recruited as controls. Among the patients with CAA who underwent amyloid-PET scans (75.0%), we investigated whether amyloid-negative cases were unevenly distributed based on cSS presentation. APOE genotypes, Mini-Mental State Examination scores, and cortical atrophy pattern along with hippocampal volume were compared across groups. RESULTS: Ten patients with probable CAA presented amyloid negativity and all of them belonged to the cSS- group (58.8%). Compared to the cSS- group, the cSS+ group presented higher APOE ε4 frequency, worse memory dysfunction, and lower hippocampal volume. Compared with cognitively normal participants, the cSS+ group exhibited atrophy in the precuneus, posterior cingulate, parietotemporal, superior frontal, and medial temporal areas, a pattern similar to AD-specific atrophy. The cSS- group exhibited atrophy in the parietotemporal, superior frontal, and precentral regions. CONCLUSION: Our findings imply that the current version of the Boston criteria may not be sufficient enough to remove non-CAA cases from a cognitively impaired population, especially in the absence of cSS. Patients with probable CAA presenting cSS appear to reflect a CAA phenotype that shares pathologic hallmarks with AD, providing insight into the CAA-to-AD continuum.

A Longitudinal Study on the Effects of Negative Rearing Experiences on Adolescents' Social Withdrawal and Aggression.

BACKGROUND: Children who have experienced negative rearing behaviors show a lack of self-confidence due to emotional instability and are reserved in interpersonal relationships. This can lead to failure in social adaptation and a high risk of depression, suicide, criminal acts, and anti-social behaviors. Therefore, this study aims to analyze the effects of experiencing negative parental rearing behaviors, such as neglect and abuse, on adolescents' social withdrawal and aggression, by utilizing multivariate latent growth models. METHODS: Data from the Korean Children and Youth Panel Study (KCYPS), a survey conducted by the National Youth Policy Institute targeting a cohort of three different age groups (grade 1, grade 4, and grade 7), from 2010 to 2016 was used. Multi-stage stratified sampling methods were used in the KCYPS, which surveyed the students and parents of the selected grade levels. This study analyzed the data for grade 7, from second year (grade 8) to fourth year (grade 10). RESULTS: Negative rearing experiences had a significant effect on social withdrawal and aggression, and this influence was shown to persist over the long term. CONCLUSION: This study examined the long-term developmental trajectory in the relationship between risk factors for adolescent development. Furthermore, the relationship between risk factors was shown to have not only short term but long-term effects as well, which reinforces the limitations of previous studies.

Tracking Cognitive Decline in Amnestic Mild Cognitive Impairment and Early-Stage Alzheimer Dementia: Mini-Mental State Examination versus Neuropsychological Battery.

BACKGROUND/AIMS: Although the Mini-Mental State Examination (MMSE), Clinical Dementia Rating-Sum of Boxes (CDR-SOB), and neuropsychological batteries are widely used for evaluating cognitive function, it remains elusive which instrument best reflects the longitudinal disease progression in amnestic mild cognitive impairment (aMCI) and probable Alzheimer disease (AD). We investigated whether changes in these three instruments over time correlate with loss of cortical gray matter volume (cGMV). METHODS: We retrospectively investigated 204 patients (aMCI, n = 114; AD, n = 90) who had undergone MMSE, CDR-SOB, the dementia version of the Seoul Neuropsychological Screening Battery (SNSB-D), and 3-dimensional T1-weighted magnetic resonance images at least twice. We investigated the partial correlation between annual decline in test scores and percent change of cGMV. RESULTS: In aMCI patients, changes in the SNSB-D total score (r = 0.340, p < 0.001) and CDR-SOB (r = 0.222, p = 0.020), but not MMSE, showed a correlation with cGMV loss, with the SNSB-D total score showing the strongest correlation. In AD patients, decline in all three test scores correlated significantly with cGMV loss, with MMSE exhibiting the strongest correlation (r = 0.464, p < 0.001). CONCLUSION: In aMCI patients, neuropsychological battery, though time-consuming, was the most adequate tool in tracking disease progression. In AD patients, however, MMSE may be the most effective longitudinal monitoring tool when considering cost-effectiveness.

Solid phase DNA extraction with a flexible bead-packed microfluidic device to detect methicillin-resistant Staphylococcus aureus in nasal swabs.

We have developed a bead-packed microfluidic device with a built-in flexible wall to automate extraction of nucleic acids from methicillin-resistant Staphylococcus aureus (MRSA) in nasal swabs. The flexible polydimethylsiloxane (PDMS) membrane was designed to manipulate the surface-to-volume ratio (SVR) of bead-packed chambers in the range of 0.05 to 0.15 (µm(-1)) for a typical solid phase extraction protocol composed of binding, washing, and eluting. In particular, the pneumatically assisted close packing of beads led to an invariant SVR (0.15 µm(-1)) even with different bead amounts (10-16 mg), which allowed for consistent operation of the device and improved capture efficiency for bacteria cells. Furthermore, vigorous mixing by asynchronous membrane vibration enabled ca. 90% DNA recovery with ca. 10 µL of liquid solution from the captured cells on the bead surfaces. The full processes to detect MRSA in nasal swabs, i.e., nasal swab collection, prefiltration, on-chip DNA extraction, and real-time polymerase chain reaction (PCR) amplification, were successfully constructed and carried out to validate the capability to detect MRSA in nasal swab samples. This flexible microdevice provided an excellent analytical PCR detection sensitivity of ca. 61 CFU/swab with 95% confidence interval, which turned out to be higher than or similar to that of the commercial DNA-based MRSA detection techniques. This excellent performance would be attributed to the capability of the flexible bead-packed microdevice to enrich the analyte from a large initial sample (e.g., 1 mL) into a microscale volume of eluate (e.g., 10 µL). The proposed microdevice will find many applications as a solid phase extraction method toward various sample-to-answer systems.

Saccharomyces cerevisiae Cmr1 protein preferentially binds to UV-damaged DNA in vitro.

DNA metabolic processes such as DNA replication, recombination, and repair are fundamentally important for the maintenance of genome integrity and cell viability. Although a large number of proteins involved in these pathways have been extensively studied, many proteins still remain to be identified. In this study, we isolated DNA-binding proteins from Saccharomyces cerevisiae using DNA-cellulose columns. By analyzing the proteins using mass spectrometry, an uncharacterized protein, Cmr1/YDL156W, was identified. Cmr1 showed sequence homology to human Damaged-DNA binding protein 2 in its C-terminal WD40 repeats. Consistent with this finding, the purified recombinant Cmr1 protein was found to be intrinsically associated with DNA-binding activity and exhibited higher affinity to UV-damaged DNA substrates. Chromatin isolation experiments revealed that Cmr1 localized in both the chromatin and supernatant fractions, and the level of Cmr1 in the chromatin fraction increased when yeast cells were irradiated with UV. These results suggest that Cmr1 may be involved in DNA-damage responses in yeast.

Miniaturized bead-beating device to automate full DNA sample preparation processes for gram-positive bacteria.

We have developed a miniaturized bead-beating device to automate nucleic acids extraction from Gram-positive bacteria for molecular diagnostics. The microfluidic device was fabricated by sandwiching a monolithic flexible polydimethylsiloxane (PDMS) membrane between two glass wafers (i.e., glass-PDMS-glass), which acted as an actuator for bead collision via its pneumatic vibration without additional lysis equipment. The Gram-positive bacteria, S. aureus and methicillin-resistant S. aureus, were captured on surface-modified glass beads from 1 mL of initial sample solution and in situ lyzed by bead-beating operation. Then, 10 µL or 20 µL of bacterial DNA solution was eluted and amplified successfully by real-time PCR. It was found that liquid volume fraction played a crucial role in determining the cell lysis efficiency in a confined chamber by facilitating membrane deflection and bead motion. The miniaturized bead-beating operation disrupted most of S. aureus within 3 min, which turned out to be as efficient as the conventional benchtop vortexing machine or the enzyme-based lysis technique. The effective cell concentration was significantly enhanced with the reduction of initial sample volume by 50 or 100 times. Combination of such analyte enrichment and in situ bead-beating lysis provided an excellent PCR detection sensitivity amounting to ca. 46 CFU even for the Gram-positive bacteria. The proposed bead-beating microdevice is potentially useful as a nucleic acid extraction method toward a PCR-based sample-to-answer system.

Functional integration of DNA purification and concentration into a real time micro-PCR chip.

Microfluidic devices for on-chip amplification of DNA from various biological and environmental samples have gained extensive attention over the past decades with many applications including molecular diagnostics of disease, food safety and biological warfare testing. But the integration of sample preparation functions into the chip remains a major hurdle for practical application of the chip-based diagnostic system. We present a PCR-based molecular diagnostic device comprised of a microfabricated chip and a centrifugal force assisted liquid handling tube (CLHT) that is designed to carry out concentration and purification of DNA and subsequent amplification of the target gene in a single chip. The reaction chamber of the chip contains an array of pillar structures to increase the surface area for capturing DNA from a raw sample of macro volume in the presence of kosmotropic agents. The CLHT was designed to provide an effective interface between sample preparation and the microfluidic PCR chip. We have characterized the effect of various fluidic parameters including DNA capture, amplification efficiency and centrifugal pressure generated upon varying sample volume. We also evaluated the performance of this system for quantitative detection of E. coli O157:H7. From the samples containing 10(1) to 10(4) cells per mL, the C(T) value linearly increased from 25.1 to 34.8 with an R(2) value greater than 0.98. With the effectiveness and simplicity of operation, this system will provide an effective interface between macro and micro systems and bridge chip-based molecular diagnosis with practical applications.

Electrochemical cell lysis device for DNA extraction.

We present a novel electrochemical cell lysis device to prepare DNA samples for lab-on-a-chip (LOC) applications. It utilizes the electrolysis of saline solution to generate hydroxide ions (OH(-)) at the cathode as alkaline lytic agents. Cathode and anode chambers are separated by a negatively-charged ion exchangeable polymer diaphragm to maintain the high pH level for efficient cell lysis in the cathode chamber, to prevent inflow of PCR-amplification inhibitors from the anode chamber, and to minimize binding of DNA molecules. Electric current flow and pH maintenance, which depended on the device design, were two important parameters of the device performance. After optimizing the design and visually confirming cell lysis of Chinese hamster ovary (CHO) cells in a very short amount of time, we directly electrolyzed four bacterial cell types suspended in saline solution. Real-time PCR (qPCR) analysis showed that our device could lyse both gram-positive and gram-negative bacterial cells with higher efficiency than other common methods and could detect DNA on the microlitre scale. Our data demonstrate several advantages of the proposed device: absence of cell lysis chemicals and heating; no adverse effects on PCR amplification; low DNA loss; low voltage and power consumption; and rapid processing. The device could potentially be applied as an on-chip DNA extraction component.

Bacterial DNA sample preparation from whole blood using surface-modified Si pillar arrays.

A novel bacterial DNA sample preparation device for molecular diagnostics has been developed. On the basis of optimized conditions for bacterial adhesion, surface-modified silicon pillar arrays for bacterial cell capture were fabricated, and their ability to capture bacterial cells was demonstrated. The capture efficiency for bacterial cells such as Escherichia coli, Staphylococcus epidermidis, and Streptococcus mutans in buffer solution was over 75% with a flow rate of 400 microL/min. Moreover, the proposed method captured E. coli cells present in 50% whole blood effectively. The captured cells from whole blood were then in- situ lyzed on the surface of the microchip, and the eluted DNA was successfully amplified by qPCR. These results demonstrate that the full process of pathogen capture to DNA isolation from whole blood could be automated in a single microchip.

Reversible capture of genomic DNA by a Nafion-coated electrode.

A method in which an electrode itself is used as the sample preparation microchip is described. The gold electrode was coated with an ion-permeable polymer, Nafion, to prevent the permanent adsorption and destruction of DNA. The modified electrode was able to capture as much DNA as the bare gold electrode and to release the captured DNA effectively, whereas the bare gold electrode could not release bound DNA. The elution efficiency was greater than 70% for the Nafion-coated electrode, whereas it was less than 10% for the bare electrode. The DNA obtained was undamaged and could be amplified by polymerase chain reaction.

Isolation of total RNA from Escherichia coli using kosmotropic Hofmeister salts.

Most of the widely used RNA isolation methods involve the use of toxic chemicals, including chaotropic salts and phenol. In an effort to solve this problem, we studied an alternative method to purify total RNA without any harmful chemicals. This method was based on silica spin columns and kosmotropic Hofmeister salts. The RNA yield was comparable to that of the commercially available RNeasy Mini Kit (Qiagen) at salt concentrations between 0.5 and 1.0 M. Furthermore, the current method allowed the isolation of small RNA molecules together with all RNA molecules longer than 200 nt.

Screening of genes related to methylglyoxal susceptibility.

Methylglyoxal (MG) is a reactive metabolite known to accumulate in certain physiological conditions. We attempted to isolate genes associated with this metabolite by genome-wide mutagenesis with TnphoA derivative. After screening on methylglyoxal-containing plate, we obtained insertions in three different genes, ydbD, yjjQ, and yqiI, which gave rise to reproducible MG-sensitive phenotypes in glyoxalase-deficient strain. In addition to its MG sensitivity, the insertion in yqiI exhibited an impaired motility resulting from a reduced flagellar expression.