Self-Assembled Monolayers Coated Porous SnO2 Film Gas Sensor with Reduced Humidity Influence.

Metal-oxide sensors, detect gas through the reaction of surface oxygen molecules with target gases, are promising for the detection of toxic pollutant gases, combustible gases, and organic vapors; however, their sensitivity, selectivity, and long-term stability limit practical applications. Porous structure for increasing surface area, adding catalyst, and altering the operation temperature are proposed for enhancing the sensitivity and selectivity. Although humidity can significantly affect the property and stability of the sensors, studies focusing on the long-term stability of gas sensors are scarce. To reduce the effects of humidity, 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (PFOTS) was coated on a porous SnO2 film. The interconnected SnO2 nanowires improved the high surface area, and the PFOTS coating provided superhydrophobicity at water contact angle of 159°and perfect water vapor repellency inside E-SEM. The superhydrophobic porous morphology was maintained under relative humidity of 99% and operating temperature of 300 °C. The CO gas sensing of 5, 20, and 50 ppm were obtained with linearity at various humidity. Flame detection was also achieved with practical high humidity conditions. These results suggest the simple way for reliable sensing of nanostructured metal-oxide gas sensors with high sensitivity and long-term stability even in highly humid environments.

Enzymatically triggered rupture of polymersomes.

Polymersomes are robust vesicles made from amphiphilic block co-polymers. Large populations of uniform giant polymersomes with defined, entrapped species can be made by templating of double-emulsions using microfluidics. In the present study, a series of two enzymatic reactions, one inside and the other outside of the polymersome, were designed to induce rupture of polymersomes. We measured how the kinetics of rupture were affected by altering enzyme concentration. These results suggest that protocells with entrapped enzymes can be engineered to secrete contents on cue.

Submicro-pillars and holes from the depth-wise Talbot images of a conical phase mask.

We construct two-dimensional arrays of submicro-pillars and holes from the depth-wise Talbot images of a conical phase mask in a photoactive layer prepared on a quartz substrate. In contrast to the conventional Talbot lithography employing only one image in the photoactive layer, two images of the phase mask are produced in a depth-wise manner such that the pillar patterns are in the primary image plane while the hole patterns in the secondary image plane according to the penetration depth of the exposure energy. The conical symmetry plays a critical role in producing the covariant patterns of the phase mask in the photoactive layer through the suppression of higher orders of diffraction. Our two image-type approach is simple and versatile for producing different kinds of periodic structures for photonic applications and surface engineering on a micrometer-to-nanometer scale.

The effect of stabilizer on the mechanical response of double-emulsion-templated polymersomes.

Recent studies have shown that polymersomes templated by microfluidic double-emulsion possess several advantages such as high monodispersity and encapsulation efficiency compared with those generated based on thin-film rehydration and electroformation. Stabilizers, including bovine serum albumin (BSA) and polyvinyl alcohol (PVA), have been used to enhance the formation and stability of double emulsions that are used as templates for the generation of polymersomes. In this work, the effect of stabilizers on the mechanical response of double-emulsion-templated polymersomes using micropipette aspiration is investigated. It is demonstrated that the existence of stabilizers results in the inelastic response in poly-mersomes in the early stage of solvent removal. However, aged polymersomes that have little residual solvent show elastic behavior. Polymersomes prepared from PVA-stabilized double emulsions have noticeably lower area expansion moduli than polymersomes prepared from stabilizer-free and BSA-stabilized double emulsions, suggesting that PVA is incorporated in the bilayer membrane of polymersomes.

Physical mechanism for flat-to-lenticular lens conversion in homogeneous liquid crystal cell with periodically undulated electrode.

A convertible lenticular liquid crystal (LC) lens architecture is demonstrated using an index-matched planarization layer on a periodically undulated electrode for the homogeneous alignment of an LC. It is found that the in-plane component of the electric field by the undulated electrode plays a primary role in the flat-to-lens effect while the out-of-plane component contributes to the anchoring enhancement of the LC molecules in the surface layer. Our LC device having an index-matched planarization layer on the undulated electrode is capable of achieving the electrical tunability from the flat surface to the lenticular lens suitable for 2D/3D convertible displays.

Biomimetic engineering of a generic cell-on-membrane architecture by microfluidic engraving for on-chip bioassays.

We develop a biomimetic cell-on-membrane architecture in close-volume format which allows the interfacial biocompatibility and the reagent delivery capability for on-chip bioassays. The key concept lies in the microfluidic engraving of lipid membranes together with biological cells on a supported substrate with topographic patterns. The simultaneous engraving process of a different class of fluids is promoted by the front propagation of an air-water interface inside a flow-cell. This highly parallel, microfluidic cell-on-membrane approach opens a door to the natural biocompatibility in mimicking cellular stimuli-response behavior essential for diverse on-chip bioassays that can be precisely controlled in the spatial and temporal manner.

Harmful gases including carcinogens produced during transurethral resection of the prostate and vaporization.

OBJECTIVE: To determine the chemical composition of surgical smoke produced during transurethral resection of the prostate (TURP) and vaporization. METHODS: A total of 12 smoke samples were collected from a continuous irrigation suction drainage system to a Tenax absorber at a 0.05L/min flow rate during TURP and vaporization. The gases were quantitatively and qualitatively analyzed by gas chromatography-mass spectrometry (GC-MS) equipped with a purge and trap sample injector. RESULTS: The main chemical constituents of surgical smoke produced during TURP and vaporization include propylene, allene, isobutylene, 1,3-butadiene, vinyl acetylene, mecaptomethane, ethyl acetylene, diacetylene, 1-pentene, EtOH, piperylene, propenylacetylene, 1,4-pentadiene, cyclopentadiene, acrylnitrile and butyrolactone. Three of the constituents are very toxic and carcinogenic (1,3-butadiene, vinyl acetylene and acrylonitrile). The amount (mean±standard deviation) of chemical components in the 45L of gas and room air mixture produced during TURP and vaporization were as follows: propylene, 0.80±0.52mg; isobutylene, 212.85±75.65mg; 1,3-butadiene, 0.93±0.34mg; ethyl acetylene, 0.09±0.05mg; 1-pentene, 6.75±1.62mg; 1,4-pentadiene, 0.06±0.02mg; and acrylonitrile, 1.62±1.19mg. CONCLUSIONS: Three of the toxic gases generated during TURP and vaporization are carcinogens (1,3-butadiene, vinyl acetylene and acrylonitrile). Therefore, higher quality filter masks, smoke evacuation devices and/or smoke filters should be developed for the safety of the operating room personnel and patients during TURP and vaporization.

Precise capture and dynamic relocation of nanoparticulate biomolecules through dielectrophoretic enhancement by vertical nanogap architectures.

Toward the development of surface-sensitive analytical techniques for biosensors and diagnostic biochip assays, a local integration of low-concentration target materials into the sensing region of interest is essential to improve the sensitivity and reliability of the devices. As a result, the dynamic process of sorting and accurate positioning the nanoparticulate biomolecules within pre-defined micro/nanostructures is critical, however, it remains a huge hurdle for the realization of practical surface-sensitive biosensors and biochips. A scalable, massive, and non-destructive trapping methodology based on dielectrophoretic forces is highly demanded for assembling nanoparticles and biosensing tools. Herein, we propose a vertical nanogap architecture with an electrode-insulator-electrode stack structure, facilitating the generation of strong dielectrophoretic forces at low voltages, to precisely capture and spatiotemporally manipulate nanoparticles and molecular assemblies, including lipid vesicles and amyloid-beta protofibrils/oligomers. Our vertical nanogap platform, allowing low-voltage nanoparticle captures on optical metasurface designs, provides new opportunities for constructing advanced surface-sensitive optoelectronic sensors.

Synthesis of Surface-Reinforced Biodegradable Chitosan Nanoparticles and Their Application in Nanostructured Antireflective and Self-Cleaning Surfaces.

Surface-reinforced chitosan nanoparticles were used instead of polystyrene nanoparticles in the nanostructuring of antireflective, self-cleaning surfaces. Nanosphere lithography is a fascinating method to fabricate functional surfaces, but a large amount of nanoparticles are used and drained. Because synthetic polymer nanoparticles cause serious ecological and biological problems, the preparation of spherical nanoparticles was attempted with biodegradable, natural polymers, including chitosan and cellulose for application in nanosphere lithography. Chitosan nanospheres can be formed with a controlled size and surface charge, whereas cellulose spherical nanoparticles are hard to make. Therefore, chitosan nanoparticles were chosen and enclosed with trichloro(phenyl)silane to enhance their stability under plasma etching. A monolayer of the surface-reinforced chitosan nanoparticles was coated on a glass surface via a floating method for nanosphere lithography to act as a mask under reactive ion etching. After etching, the nanostructured glass showed a 2% increased transmittance compared with bare glass at 550 nm due to an antireflective effect. Moreover, the nanostructured glass with perfluoropolyether coating had a water contact angle of 152° and exhibited superhydrophobicity and a self-cleaning effect. This work addresses the issues of ecofriendly nanostructuring based on biodegradable, natural polymer nanoparticles for energy- and water-saving applications of nanostructured surfaces, by demonstrating the practical utilization of chitosan nanoparticles in nanosphere lithography.

The current status of hormone treatment for prostate cancer patients in Korean real-world practice: a multi-institutional observational study.

We aimed to evaluate the current nationwide trend, efficacy, safety, and quality of life (QoL) profiles of hormone treatment in real-world practice settings for prostate cancer (PCa) patients in Korea. A total of 292 men with any biopsy-proven PCa (TanyNanyMany) from 12 institutions in Korea were included in this multi-institutional, observational study of prospectively collected data. All luteinizing hormone-releasing hormone (LHRH) agonists were allowed to be investigational drugs. Efficacy was defined as (1) the rate of castration (serum testosterone ≤50 ng dl-1) at 4-week visit and (2) breakthrough (serum testosterone >50 ng dl-1 after castration). Safety assessments included routine examinations for potential adverse events, laboratory tests, blood pressure, body weight, and bone mineral density (BMD, at baseline and at the last follow-up visit). QoL was assessed using the Expanded Prostate Cancer Index Composite-26 (EPIC-26). The most common initial therapeutic regimen was LHRH agonist with anti-androgen (78.0%), and the most commonly used LHRH agonist for combination and monotherapy was leuprolide (64.0% for combination and 58.0% for monotherapy). The castration and breakthrough rates were 78.4% and 6.6%, respectively. The laboratory results related to dyslipidemia worsened after 4 weeks of hormone treatment. In addition, the mean BMD T-score was significantly lower at the last follow-up (mean: -1.950) compared to baseline (mean: -0.195). The mean total EPIC-26 score decreased from 84.8 (standard deviation [s.d.]: 12.2) to 78.3 (s.d.: 8.1), with significant deterioration only in the urinary domain (mean: 23.5 at baseline and 21.9 at the 4-week visit). These findings demonstrate the nationwide trend of current practice settings in hormone treatment for PCa in Korea.

Immunogenicity and safety of Vi capsular polysaccharide typhoid vaccine in healthy persons in Korea.

The purpose of this study was to evaluate the immunogenicity and safety of Salmonella Typhi Vi capsular polysaccharide vaccine (Vi vaccine) in Korea. The immunogenicity of a single dose of Vi vaccine was evaluated in 157 subjects (75 children and 82 adults) before and at 1, 6, and 12 months after vaccination. Immunogenicity was measured with a passive hemagglutination assay (PHA), quantified as geometric mean titers (GMTs) and seroconversion rates. The safety of the vaccine was investigated by determining adverse reactions occurring within 4 h, 3 days, and 1 month after injection. The seroconversion rate for children and adults 1 month after vaccination was 96.92% and 89.02%, respectively. In the case of children, the GMTs of Vi antibodies before vaccination were 5.87 +/- 1.34 and 142.59 +/- 2.39 at one month after vaccination. For adults, the GMTs before and one month after vaccination were 5.58 +/- 1.28 and 58.56 +/- 3.67, respectively. Vi antibodies persisted for as long as 6 and 12 months after vaccination. All adverse reactions in adults and children were minor and did not require treatment. The Vi CPS vaccine was safe and immunogenic in adults and children older than 5 years.

An Asian study on the prevalence of atypical respiratory pathogens in community-acquired pneumonia.

BACKGROUND: In many parts of Asia, the inaccessibility and high cost of diagnostic tests have hampered the study of community-acquired pneumonia (CAP) caused by atypical respiratory pathogens. OBJECTIVE: This surveillance study examined the frequency of infection with Mycoplasma pneumoniae, Chlamydophila pneumoniae, and Legionella pneumophila in 1756 patients presenting with signs and symptoms of CAP at 12 medical centres in Asia, using standardised laboratory techniques and interpretation criteria in all participating centres. METHODS: Diagnosis of current infection was based on significant changes in antibody titer or persisting high antibody titers, together with the presence of bacterial DNA in respiratory secretions, in the case of M. pneumoniae and C. pneumoniae infections, or bacterial antigen in urine, in the case of L. pneumophila serogroup 1 infection. RESULTS: Using these criteria, results from 1374 patients with paired sera showed that, overall, 23.5% of CAP cases were associated with infection with atypical respiratory pathogens, with M. pneumoniae, C. pneumoniae, and L. pneumophila being found in 12.2%, 4.7%, and 6.6% of cases, respectively. Persisting high antibody titers indicative of past exposure to M. pneumoniae, C. pneumoniae, and L. pneumophila were seen in 10.2%, 4.8%, and 18.9% of patients, respectively. CONCLUSION: These data reflect the overall high prevalence of these atypical pathogens among Asian patients with CAP.

Comparison of responses elicited by immunization with a Legionella species common lipoprotein delivered as naked DNA or recombinant protein.

To evaluate the peptidoglycan-associated lipoprotein (PAL) antigen of Legionella pneumophila as a vaccine candidate, mice were immunized intramuscularly with pcDNA3-PAL and intraperitoneally with recombinant PAL (t-rPAL), which were compared for their ability to induce PAL-specific immune responses. The t-rPAL protein induced PAL-specific IgG antibody production significantly more than did pcDNA3-PAL. The IgG2a and IgG1 production was predominant after pcDNA3-PAL and t-rPAL administration, respectively. In particular, pcDNA3-PAL induced much higher PAL-specific cytotoxic T-lymphocyte responses than did t-rPAL. Furthermore, in vivo, CD19+ B-cell populations were dramatically increased by t-rPAL vaccination, suggesting a B-cell immunomodulatory activity of the lipoprotein. The PAL antigen was also conserved among Legionella species, as determined by PCR and immunoblot analyses. These results support a potential use of the t-rPAL protein and in particular DNA vaccines against Legionella infections.

Clinical and molecular epidemiology of quinolone-resistant Escherichia coli isolated from urinary tract infection.

Since the use of fluoroquinolone antibiotic in clinical practice was introduced about a decade ago, quinolone-resistant E. coli (QREC) strains are being isolated with increasing frequency. From 1996 to 2000, 297 cases of urinary tract infection (UTI) due to QREC were observed in our hospital; 218 episodes (73.5%) were community acquired. The incidence of QREC UTIs increased steadily from 14.4% to 21.3% during 5 years when we compared the clinical characteristics of 60 QREC UTI with those of 80 quinolone-susceptible E. coli UTIs. Significant differences in susceptibility to various antibiotics were observed between the QREC and QSEC strains of E. coli. The multidrug resistance rate of QREC was much higher (38.3%) than those of quinolone susceptible isolates (18.8%). Prior fluoroquinolone use (p = 0.05), old age (p = 0.001), and a vegetative state (p = 0.03) were the independent risk factors for the acquisition of QREC UTI. The outcome of E. coli UTI is dependent on quinolone resistance. Thirty-day mortality was higher in QREC UTI patients, probably due to aggravation of underlying illness, but not quinolone resistance. On the basis of PFGE analysis, although some clustering was found in the hospital, genomic diversity was found among both the community and nosocomial strains. The increased frequency of QREC UTIs is thus not due to transmission of resistant strains but probably results from the selection of resistant strains from the endogenous flora of patients.

Comparison of immune preservation between CO2 pneumoperitoneum and gasless abdominal lift laparoscopy.

OBJECTIVE: Carbon dioxide (CO2) pneumoperitoneum has been implicated as a possible factor in early immune preservation in laparoscopic surgery. Although the current analysis was not adequate to clarify this issue, the aim of this study was to compare CO2 insufflation laparoscopic cholecystectomy to gasless abdominal wall lift laparoscopic cholecystectomy with respect to preservation of the immune system. METHOD: An analysis of the temporal immune responses was performed in 2 similar groups of patients (n = 50) who were divided randomly into the categories of gas or abdominal wall lift laparoscopic cholecystectomy. The patients were matched with respect to age, weight, and operation time. The immune parameters (serum white blood cell count, cortisol, erythrocyte sedimentation rate [ESR], tumor necrosis factor-alpha [TNF-alpha], interferon-y [INF-gamma], interleukin-6 [IL-6], interleukin-8 [IL-8]) were assessed at preoperative 24 hours and at postoperative 24 and 72 hours for the 2 groups. During the operation, the levels of cytokines that were cultured in the peritoneal macrophages were also checked. RESULTS: The serum white blood cell count, cortisol, and ESR levels were not statistically different in either of the 2 groups. Further, the serum TNF-alpha, INF-gamma, IL-6, and IL-8 levels in both groups were not significantly different from each other at preoperative 24 hours, and postoperative 24 and 72 hours. However, an immediate decrease in the cytokine levels at 24 hours after the operation was significant in both groups. The cytokine levels were particularly higher in the cultured peritoneal macrophages than in the serum, but were not statistically different between the 2 groups. CONCLUSION: Our results showed that the beneficial immune response obtained in the CO2 gas insufflation laparoscopic procedure could also be obtained in the gasless abdominal wall lift laparoscopic procedure. An immediate preservation of the immune functions in the postoperative period was detected similarly in the 2 groups.

Reconstituting ring-rafts in bud-mimicking topography of model membranes.

During vesicular trafficking and release of enveloped viruses, the budding and fission processes dynamically remodel the donor cell membrane in a protein- or a lipid-mediated manner. In all cases, in addition to the generation or relief of the curvature stress, the buds recruit specific lipids and proteins from the donor membrane through restricted diffusion for the development of a ring-type raft domain of closed topology. Here, by reconstituting the bud topography in a model membrane, we demonstrate the preferential localization of cholesterol- and sphingomyelin-enriched microdomains in the collar band of the bud-neck interfaced with the donor membrane. The geometrical approach to the recapitulation of the dynamic membrane reorganization, resulting from the local radii of curvatures from nanometre-to-micrometre scales, offers important clues for understanding the active roles of the bud topography in the sorting and migration machinery of key signalling proteins involved in membrane budding.

Realizing the concept of a scalable artificial iris with self-regulating capability by reversible photoreaction of spiropyran dyes.

We report a scalable artificial iris with self-regulating spoke patterns of a liquid crystalline polymer that resemble the iris frills of the human eye. The underlying concept relies primarily on the reversible photo-induced conformation change of spiropyran dyes embedded in a transparent polymer. The spoke patterns around the scalable pupil, defined by selective wetting inscription, were produced using reactive liquid crystalline mesogens on a flexible substrate through polymerization. The self-regulation capability of our artificial iris, not requiring driving circuits and peripheral sensors, plays a central role in developing a new class of biomedical and photonic devices in a monolithic architecture.

Polymorphic meniscus convergence for construction of quasi-periodic assemblies and networks of colloidal nanoparticles.

Quasi-periodic colloidal networks are constructed on the basis of polymorphic meniscus convergence (MC) in an air-cavity-embedded, nano-colloidal system. Depending on the flow associated with the air-cavities, the colloidal particles are self-organized into nanowires through binary MC, Y-junctions through ternary MC, and X-junctions through quaternary MC. The colloidal networks in either square or hexagonal form reflect the flow symmetry according to the air-cavity deformation.

Atypical pathogens as etiologic agents in hospitalized patients with community-acquired pneumonia in Korea: a prospective multi-center study.

Local epidemiologic data on the etiologies of patients hospitalized with community-acquired pneumonia (CAP) is needed to develop guidelines for clinical practice. This study was conducted prospectively to determine the proportion of atypical bacterial pathogens in adults patients hospitalized with CAP in Korea between October 2001 and December 2002. Microbiological diagnosis was determined by serology for antibodies to Mycoplasma pneumoniae, Chlamydia pneumoniae, and Legionella pneumophila. Nucleic acid of M. pneumoniae and C. pneumoniae in respiratory samples and Legionella antigen in urine samples were detected. The study population consisted of 126 patients (71 males, 55 females), averaging 54.6 yr (SD+/-17.8), whose paired sera were available. An etiologic diagnosis for atypical pathogens was made in 18 patients (14.3%): C. pneumoniae 9 (7.1%), M. pneumoniae 8 (6.3%), and L. pneumophila 3 patients (2.4%). Streptococcus preumoniae and other typical pathogens were isolated from 36 patients (28.6%). Of 126 patients, 16 (12.7%) were admitted to intensive care unit and atypical pathogens were identified in 5 patients (31.3%). Initial clinical features of patients with pneumonia due to atypical, typical or undetermined pathogens were indistinguishable. We conclude that atypical pathogens should be seriously considered in hospitalized patients with CAP, when initiating empiric treatment in Korea.

Epidemiology of hemorrhagic fever with renal syndrome in endemic area of the Republic of Korea, 1995-1998.

We conducted an epidemiologic study to understand temporal and spatial patterns of hemorrhagic fever with renal syndrome (HFRS) in the Republic of Korea (ROK). We estimated the incidence among civilians in endemic areas through the active surveillance system during the major epidemic periods, from September to December, between 1996 and 1998. We also estimated the prevalence among Korean military personnel from 1995 to 1998. In addition, we assessed seroprevalence, subclinical infection rate, and vaccination rates in both civilians and military personnel. The incidence in civilians ranged from 2.1 to 6.6 per 100, 000 person-months. The annual prevalence in the military personnel was 40-64 per 100, 000 military populations, and remained generally constant throughout the study period with seasonal variation. This is the prospective epidemiologic data set on HFRS in the ROK since the inactivated Hantaan virus vaccine was licensed for use in the late 1990s. These results will be invaluable in establishing a national immunization program against HFRS.