Metal-organic framework based on hinged cube tessellation as transformable mechanical metamaterial

Mechanical metamaterials exhibit unusual properties, such as negative Poisson???s ratio, which are difficult to achieve in conventional materials. Rational design of mechanical metamaterials at the microscale is becoming popular partly because of the advance in three-dimensional printing technologies. However, incorporating movable building blocks inside solids, thereby enabling us to manipulate mechanical movement at the molecular scale, has been a difficult task. Here, we report a metal-organic framework, self-assembled from a porphyrin linker and a new type of Zn-based secondary building unit, serving as a joint in a hinged cube tessellation. Detailed structural analysis and theoretical calculation show that this material is a mechanical metamaterial exhibiting auxetic behavior. This work demonstrates that the topology of the framework and flexible hinges inside the structure are intimately related to the mechanical properties of the material, providing a guideline for the rational design of mechanically responsive metal-organic frameworks

Anti-biofouling Coating by Wrinkled, Dual-roughness Structures of Diamond-like Carbon (DLC)

The textured surface with superhydrophobic nature was explored for an anti-biofouling template. Hierarchical structures composed of the nano-scale wrinkle covering on micro-scale polymer pillar patterns were fabricated by combining the deposition of a thin coating layer of biocompatible diamond-like carbon (DLC) and the replica molding of poly-(dimethylsiloxane) (PDMS) micro-pillars. The as-prepared surfaces were shown to have extreme hydrophobicity (static contact angle > 160 degrees) owing to low surface energy (24.2 mN/m) and dual-roughness structures of the DLC coating. It was explored that the hierarchical surfaces showed poor adhesion of the Calf Pulmonary Artery Endothelial (CPAE) cells for cultures of 7 days suggesting that the 3-dimensional (3-D) patterned superhydrophobic DLC coating exhibits excellent anti-biofouling properties against non-specific cell adhesion. In particular, the reduced filopodia extension during cell growth was caused by disconnected focal adhesions on the pillar pattern. This limited cell adhesion could prevent undesired growth and proliferation of biological species on the surface of biomedical devices such as stents, implants or even injection syringes.This work was supported by Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea government (MOST) (R01-2007-000-20675-0), the Micro Thermal System Research Center of Seoul National University, and the Korea Research Foundation Grant funded by the Korean Government (MOEHRD) (Grant KRF-J03003). This work was supported in part by a grant (06K1501-01610) from the CNMT under the 21st Century Frontier R&D Programs of MEST of Korea (MWM, KRL)

Clinical features of adolescents with suicide attempt and the factors associated with their outcomes: poisoning versus non-poisoning

Purpose Methods for suicide attempt are largely divided into poisoning and non-poisoning, which differ in clinical features and severity. We aimed to investigate the clinical features of adolescents with suicide attempt and factors associated with poor outcomes from the 2 methods. Methods A retrospective study was conducted on adolescents (10-18 years) who visited the emergency department after suicide attempt from 2011 through 2018. The adolescents were divided into the poisoning and non-poisoning groups. We analyzed the differences of clinical features and outcomes between the 2 groups. Poor outcomes were defined as hospitalization to the intensive care unit or death. Factors associated with poor outcomes were investigated using multivariable logistic regression. Results Of 4,335 adolescents in total, 2,134 (49.2%) were categorized as the poisoning group. In this group, the adolescents with poor outcomes used acetaminophen most frequently (26.5%), followed by sedative or antipsychotics (22.3%). In the non-poisoning group, those with the outcomes used fall from height (73.2%) most commonly, followed by hanging (21.0%). The factors associated with the outcomes were age (for increment of 1 year; odds ratio, 1.11; 95% confidence interval, 1.02-1.22) in the poisoning group, and being boys (1.34; 1.03-1.73) and non-use of alcohols (2.87; 1.73-4.74) in the non-poisoning group. Conclusion In adolescents who used poisoning for suicide attempt, increasing age is associated with poor outcomes. The outcomes are associated with being boys and non-use of alcohols in those who used non-poisoning methods

Nepmucin, a novel HEV sialomucin, mediates L-selectin–dependent lymphocyte rolling and promotes lymphocyte adhesion under flow

Lymphocyte trafficking to lymph nodes (LNs) is initiated by the interaction between lymphocyte L-selectin and certain sialomucins, collectively termed peripheral node addressin (PNAd), carrying specific carbohydrates expressed by LN high endothelial venules (HEVs). Here, we identified a novel HEV-associated sialomucin, nepmucin (mucin not expressed in Peyer's patches [PPs]), that is expressed in LN HEVs but not detectable in PP HEVs at the protein level. Unlike conventional sialomucins, nepmucin contains a single V-type immunoglobulin (Ig) domain and a mucin-like domain. Using materials affinity-purified from LN lysates with soluble L-selectin, we found that two higher molecular weight species of nepmucin (75 and 95 kD) were decorated with oligosaccharides that bind L-selectin as well as an HEV-specific MECA-79 monoclonal antibody. Electron microscopic analysis showed that nepmucin accumulates in the extended luminal microvillus processes of LN HEVs. Upon appropriate glycosylation, nepmucin supported lymphocyte rolling via its mucin-like domain under physiological flow conditions. Furthermore, unlike most other sialomucins, nepmucin bound lymphocytes via its Ig domain, apparently independently of lymphocyte function–associated antigen 1 and very late antigen 4, and promoted shear-resistant lymphocyte binding in combination with intercellular adhesion molecule 1. Collectively, these results suggest that nepmucin may serve as a dual-functioning PNAd in LN HEVs, mediating both lymphocyte rolling and binding via different functional domains

A Case of Cerebral Gumma Presenting as Brain Tumor in a Human Immunodeficiency Virus (HIV)-Negative Patient

Syphilis, along with the recent increase of human immunodeficiency virus (HIV) patients, has also been on the rise. It has a broad spectrum of clinical manifestations, among which cerebral gumma is, a kind of neurosyphilis, however, it is rare and can be cured by penicillin. Thus, cerebral gumma needs to be differentially diagnosed from other brain masses that may be present in syphilis patients. We have experienced a case where the patient was first suspected of brain tumor, but confirmed by surgery to be cerebral gumma due to neurosyphilis. This is the first such case encountered in Korea, therefore, we report it here in. A 40-year old woman complaining of headaches was found to have a brain mass on her CT scans and MRI. Suspecting a brain Tumor, a resection was performed on the patient, and histological results revealed that the central portion of the mass contained necrotic material and the peripheral region was infiltrated with plasma cells. Warthin-Starry staining of the region revealed spirochetes, and the patient was thus diagnosed as brain gumma. Venereal Disease Research Laboratory (VDRL) of cerebrospinal fluid (CSF) was reactive. After an operation, penicillin-G at a daily dose of 24×106 U was given for 10 days from post-operative day 10, and thereafter, the mass disappeared

A Case of Poikiloderma Vasculare Atrophicans

Poikiloderma vasculare atrophicans (PVA) is a rare variant of mycosis fungoides, and is characterized by generalized hyperkeratotic scaly papules in net-like, retiform, or zebra-like patterns. A 59-year-old Korean woman presented with asymptomatic, erythematous-to-violaceous, reticulated confluent papules on the trunk and extremities. Skin lesions were initially limited to both thighs 25 years ago, and then spread slowly over her body. Histopathological examination showed band-like inflammatory infiltrations and epidermotropism consisting of mostly CD8+ lymphocytes. Based on the clinical manifestations and histological findings, the diagnosis of PVA was made. We herein report on a case of PVA, which featured a long-benign course without progression into the tumor stage over a period of 30 years

Effect of steroids and relevant cytokine analysis in acute tubulointerstitial nephritis

Background Acute tubulointerstitial nephritis (ATIN) is an important cause of acute kidney injury and often a potentially reversible disease. However, the role of steroids in ATIN remains controversial and the underlying mechanisms remain unresolved. Methods A total of 113 adult patients with biopsy-proven ATIN were recruited from three tertiary referral centers. Of 102 patients with idiopathic or drug-induced ATIN, outcomes such as renal recovery, end-stage renal disease, and all-cause mortality were compared between the steroid-treated and non-treated groups. Plasma and urine inflammatory cytokine levels at the time of biopsy were analyzed in patients (n = 33) using a bead-based multiplex assay and compared with those of healthy individuals (n = 40). Results Steroids were used in 92 (81.4%) of the total patients and in 82 (80.3%) patients with idiopathic or drug-induced ATIN. The rate of renal recovery and the risks of end-stage renal disease and mortality were not different between the steroid-treated and non-treated groups. Despite using a propensity score matching method (n = 20 in each group), none of the outcomes were different between the two groups. Several cytokines, such as monocyte chemotactic protein-1, interferon-α, and interleukin-6 and interleukin-8 levels, were markedly elevated in plasma and urine of patients compared with those in healthy individuals. However, cytokines related to Th2 response, such as IL-10, IL-33, were not different between the two groups. Conclusions Steroid use does not affect the overall outcome of ATIN. Based on the fact that targeting therapy should be investigated to improve outcomes, the present cytokine results will be helpful for developing a novel therapy for ATIN.This work was supported by a grant from the Basic Science Research Program through the National Research Foundation of Korea (NRF), which is funded by the Ministry of Education (NRF-2017R1D1A1B03031642)

Interlayer orientation-dependent light absorption and emission in monolayer semiconductor stacks

Two-dimensional stacks of dissimilar hexagonal monolayers exhibit unusual electronic, photonic and photovoltaic responses that arise from substantial interlayer excitations. Interband excitation phenomena in individual hexagonal monolayer occur in states at band edges (valleys) in the hexagonal momentum space; therefore, low-energy interlayer excitation in the hexagonal monolayer stacks can be directed by the two-dimensional rotational degree of each monolayer crystal. However, this rotation-dependent excitation is largely unknown, due to lack in control over the relative monolayer rotations, thereby leading to momentum-mismatched interlayer excitations. Here, we report that light absorption and emission in MoS2/WS2 monolayer stacks can be tunable from indirect- to direct-gap transitions in both spectral and dynamic characteristics, when the constituent monolayer crystals are coherently stacked without in-plane rotation misfit. Our study suggests that the interlayer rotational attributes determine tunable interlayer excitation as a new set of basis for investigating optical phenomena in a two-dimensional hexagonal monolayer system.open115850sciescopu

Ocular Manifestations of Acquired Immunodeficiency Syndrome in Korea

The clinical features of HIV/AIDS-related ocular manifestations in Korean patients were investigated in this study. Data on 200 consecutive Korean patients diagnosed with AIDS who visited the Seoul National University Hospital from January 2003 to June 2008 were reviewed. Fifty-seven patients (28.5%) had ocular manifestations, and they showed significantly lower CD4+ T cell count than patients without ocular manifestations. Among them, 23 (40.3%) patients showed retinal microvasculopathy, and 22 (38.5%) patients showed cytomegalovirus (CMV) retinitis. Other manifestations included retinal vein occlusion (n = 4), herpes zoster ophthalmicus (n = 4), syphilitic uveitis (n = 2), acute retinal necrosis (n = 1), and progressive outer retinal necrosis (n = 1). The mean CD4+ lymphocyte counts of the patients with retinal microvasculopathy and cytomegalovirus retinitis were 108.5 cells/µL and 69.4 cells/µL, respectively. In conclusion, ocular manifestations including CMV retinitis are common complications in Korean patients with AIDS even in the era of highly active anti-retroviral therapy. Compared to previous reports in western countries, prevalence of CMV retinitis is relatively low and CD4+ lymphocytes count at the time of diagnosis is relatively high