Early Sepsis-Associated Acute Kidney Injury and Obesity

Importance

The prevalence of obesity is increasing in the intensive care unit (ICU). Although obesity is a known risk factor for chronic kidney disease, its association with early sepsis-associated acute kidney injury (SA-AKI) and their combined association with patient outcomes warrant further investigation.

Objective

To explore the association between obesity, early SA-AKI incidence, and clinical outcomes in patients with sepsis.

Design, Setting, and Participants

This nationwide, prospective cohort study analyzed patients aged 19 years or older who had sepsis and were admitted to 20 tertiary hospital ICUs in Korea between September 1, 2019, and December 31, 2021. Patients with preexisting stage 3A to 5 chronic kidney disease and those with missing body mass index (BMI) values were excluded.

Exposures

Sepsis and hospitalization in the ICU.

Main Outcomes and Measures

The primary outcome was SA-AKI incidence within 48 hours of ICU admission, and secondary outcomes were mortality and clinical recovery (survival to discharge within 30 days). Patients were categorized by BMI (calculated as weight in kilograms divided by height in meters squared), and data were analyzed by logistic regression adjusted for key characteristics and clinical factors. Multivariable fractional polynomial regression models and restricted cubic spline models were used to analyze the clinical outcomes with BMI as a continuous variable.

Results

Of the 4041 patients (median age, 73 years [IQR, 63-81 years]; 2349 [58.1%] male) included in the study, 1367 (33.8%) developed early SA-AKI. Obesity was associated with a higher incidence of SA-AKI compared with normal weight (adjusted odds ratio [AOR], 1.40; 95% CI, 1.15-1.70), as was every increase in BMI of 10 (OR, 1.75; 95% CI, 1.47-2.08). While obesity was associated with lower in-hospital mortality in patients without SA-AKI compared with their counterparts without obesity (ie, underweight, normal weight, overweight) (AOR, 0.72; 95% CI, 0.54-0.94), no difference in mortality was observed in those with SA-AKI (AOR, 0.85; 95% CI, 0.65-1.12). Although patients with obesity without SA-AKI had a greater likelihood of clinical recovery than their counterparts without obesity, clinical recovery was less likely among those with both obesity and SA-AKI.

Conclusions and Relevance

In this cohort study of patients with sepsis, obesity was associated with a higher risk of early SA-AKI and the presence of SA-AKI modified the association of obesity with clinical outcomes.

Mechanical Control of Polaritonic States in Lead Halide Perovskite Phonons Strongly Coupled in THz Microcavity

We demonstrate the generation and control of polaritonic states in perovskite phonon polaritons, which are strongly coupled in the middle of a flexible Fabry-Perot cavity. We fabricated flexible perovskite films on a microporous substrate coated with graphene oxide, which led to a virtually free-standing film incorporated into the microcavity. Rabi splitting was observed when the cavity resonance was in tune with that of the phonons. The Rabi splitting energy increased as the film thickness increased, reaching 1.9 meV, which is 2.4-fold higher than the criterion for the strong coupling regime. We obtained dispersion curves for various perovskite film thicknesses exhibiting two polariton branches; clear beats between the two polaritonic branches were observed in the time domain. Flexible cavity devices with perovskite phonons enable macroscopic control over the polaritonic energy states through bending processes, which add an additional degree of freedom in the manipulation of polaritonic devices.

Factors influencing sleep quality in the intensive care unit: a descriptive pilot study in Korea

BACKGROUND

As sleep disturbances are common in the intensive care unit (ICU), this study assessed the sleep quality in the ICU and identified barriers to sleep.

METHODS

Patients admitted to the ICUs of a tertiary hospital between June 2022 and December 2022 who were not mechanically ventilated at enrollment were included. The quality of sleep (QoS) at home was assessed on a visual analog scale as part of an eight-item survey, while the QoS in the ICU was evaluated using the Korean version of the Richards-Campbell Sleep Questionnaire (K-RCSQ). Good QoS was defined by a score of ≥50.

RESULTS

Of the 30 patients in the study, 19 reported a QoS score <50. The Spearman correlation coefficient showed no meaningful relationship between the QoS at home and the overall K-RCSQ QoS score in the ICU (r=0.16, P=0.40). The most common barriers to sleep were physical discomfort (43%), being awoken for procedures (43%), and feeling unwell (37%); environmental factors including noise (30%) and light (13%) were also identified sources of sleep disruption. Physical discomfort (median [interquartile range]: 32 [28.0-38.0] vs. 69 [42.0-80.0], P=0.004), being awoken for procedures (36 [20.0-48.0] vs. 54 [36.0-80.0], P=0.04), and feeling unwell (31 [18.0-42.0] vs. 54 [40.0-76.0], P=0.01) were associated with lower K-RCSQ scores.

CONCLUSIONS

In the ICU, physical discomfort, patient care interactions, and feeling unwell were identified as barriers to sleep.

Association between the timing of ICU admission and mortality in patients with hospital-onset sepsis: a nationwide prospective cohort study

BACKGROUND

Based on sparse evidence, the current Surviving Sepsis Campaign guideline suggests that critically ill patients with sepsis be admitted to the intensive care unit (ICU) within 6 h. However, limited ICU bed availability often makes immediate transfer difficult, and it is unclear whether all patients will benefit from early admission to the ICU. Therefore, the purpose of this study was to determine the association between the timing of ICU admission and mortality in patients with hospital-onset sepsis.

METHODS

This nationwide prospective cohort study analyzed patients with hospital-onset sepsis admitted to the ICUs of 19 tertiary hospitals between September 2019 and December 2020. ICU admission was classified as either early (within 6 h) or delayed (beyond 6 h). The primary outcome of in-hospital mortality was compared using logistic regression adjusted for key prognostic factors in the unmatched and 1:1 propensity-score-matched cohorts. Subgroup and interaction analyses assessed whether in-hospital mortality varied according to baseline characteristics.

RESULTS

A total of 470 and 286 patients were included in the early and delayed admission groups, respectively. Early admission to the ICU did not significantly result in lower in-hospital mortality in both the unmatched (adjusted odds ratio [aOR], 1.35; 95% confidence interval [CI], 0.99-1.85) and matched cohorts (aOR, 1.38; 95% CI, 0.94-2.02). Subgroup analyses showed that patients with increasing lactate levels (aOR, 2.10; 95% CI, 1.37-3.23; P for interaction = 0.003), septic shock (aOR, 2.06; 95% CI, 1.31-3.22; P for interaction = 0.019), and those who needed mechanical ventilation (aOR, 1.92; 95% CI, 1.24-2.96; P for interaction = 0.027) or vasopressor support (aOR, 1.69; 95% CI, 1.17-2.44; P for interaction = 0.042) on the day of ICU admission had a higher risk of mortality with delayed admission.

CONCLUSIONS

Among patients with hospital-onset sepsis, in-hospital mortality did not differ significantly between those with early and delayed ICU admission. However, as early intensive care may benefit those with increasing lactate levels, septic shock, and those who require vasopressors or ventilatory support, admission to the ICU within 6 h should be considered for these subsets of patients.

Validation of Practical Pathway in Patients With Anaphylaxis to Low Osmolar Contrast Media: A Retrospective Cohort Study

BACKGROUND

An optimal strategy for choosing safe alternative low osmolar contrast media (LOCM) has not yet been established in patients with a history of LOCM-induced anaphylaxis.

OBJECTIVES

To validate the practical pathway in patients with anaphylaxis to LOCMs and to compare 2 different doses of challenge testing with skin test-negative LOCM.

METHODS

A retrospective cohort study was performed in patients with LOCM-induced anaphylaxis. Patients were challenged with intravenous LOCMs showing negativity in the skin test according to 2 different protocols: low-dose and high-dose (maximum dose 10 and 30 mL, respectively). Challenge-negative LOCMs were selected for use during computed tomography scans, and patients received intravenous pretreatment with 4 mg chlorpheniramine and 40 mg methylprednisolone.

RESULTS

Of the 110 challenge tests, there were 4 (3.6%) positive challenges. Among 106 enhanced computed tomography scans performed using challenge-negative LOCMs, breakthrough reactions occurred in 8 (7.6%). Breakthrough reaction rates were not statistically different between the 2 protocols (8.9% and 6.0% in the low-dose challenge and the high-dose challenge, respectively). Compared with the low-dose protocol, the number needed to test of the high-dose challenge test decreased 2.5-fold. Moreover, none of the patients in the high-dose challenge group incurred severe reactions during computed tomography scans with challenge-negative LOCM, whereas 80% of reactions were severe in the low-dose challenge group.

CONCLUSIONS

We validated a pathway consisting of a battery of skin testing to LOCMs and challenge with skin test-negative LOCM in patients with LOCM-induced anaphylaxis.

Peripheral blood transcriptomic clusters uncovered immune phenotypes of asthma

BACKGROUND

Transcriptomic analysis has been used to elucidate the complex pathogenesis of heterogeneous disease and may also contribute to identify potential therapeutic targets by delineating the hub genes. This study aimed to investigate whether blood transcriptomic clustering can distinguish clinical and immune phenotypes of asthmatics, and microbiome in asthmatics.

METHODS

Transcriptomic expression of peripheral blood mononuclear cells (PBMCs) from 47 asthmatics and 21 non-asthmatics was measured using RNA sequencing. A hierarchical clustering algorithm was used to classify asthmatics. Differentially expressed genes, clinical phenotypes, immune phenotypes, and microbiome of each transcriptomic cluster were assessed.

RESULTS

In asthmatics, three distinct transcriptomic clusters with numerously different transcriptomic expressions were identified. The proportion of severe asthmatics was highest in cluster 3 as 73.3%, followed by cluster 2 (45.5%) and cluster 1 (28.6%). While cluster 1 represented clinically non-severe T2 asthma, cluster 3 tended to include severe non-T2 asthma. Cluster 2 had features of both T2 and non-T2 asthmatics characterized by the highest serum IgE level and neutrophil-dominant sputum cell population. Compared to non-asthmatics, cluster 1 showed higher CCL23 and IL1RL1 expression while the expression of TREML4 was suppressed in cluster 3. CTSD and ALDH2 showed a significant positive linear relationship across three clusters in the order of cluster 1 to 3. No significant differences in the diversities of lung and gut microbiomes were observed among transcriptomic clusters of asthmatics and non-asthmatics. However, our study has limitations in that small sample size data were analyzed with unmeasured confounding factors and causal relationships or function pathways were not verified.

CONCLUSIONS

Genetic clustering based on the blood transcriptome may provide novel immunological insight, which can be biomarkers of asthma immune phenotypes. Trial registration Retrospectively registered.

Terahertz thermal curve analysis for label-free identification of pathogens

In this study, we perform a thermal curve analysis with terahertz (THz) metamaterials to develop a label-free identification tool for pathogens such as bacteria and yeasts. The resonant frequency of the metasensor coated with a bacterial layer changes as a function of temperature; this provides a unique fingerprint specific to the individual microbial species without the use of fluorescent dyes and antibodies. Differential thermal curves obtained from the temperature-dependent resonance exhibit the peaks consistent with bacterial phases, such as growth, thermal inactivation, DNA denaturation, and cell wall destruction. In addition, we can distinguish gram-negative bacteria from gram-positive bacteria which show strong peaks in the temperature range of cell wall destruction. Finally, we perform THz melting curve analysis on the mixture of bacterial species in which the pathogenic bacteria are successfully distinguished from each other, which is essential for practical clinical and environmental applications such as in blood culture.

A label-free sensing method has been developed for identifying hazardous pathogens based on their intrinsic properties. This was possible by interrogating the temperature-dependent dielectric constant of the microbes in the far-infrared range.

Allergic-like Hypersensitivity Reactions to Gadolinium-based Contrast Agents: An 8-year Cohort Study of 154 539 Patients

Background With the widespread use of gadolinium-based contrast agents (GBCAs), the incidence of allergic-like hypersensitivity reactions (HSRs) to GBCAs is increasing. Research on the incidence and risk factors for HSRs to GBCAs is needed for their safe use. Purpose To determine the incidence of acute and delayed reactions to GBCAs and to discuss the risk factors and strategies for the prevention of HSRs to GBCAs. Materials and Methods All cases of HSRs to contrast media that occurred at the Seoul National University Hospital from July 1, 2012, to June 30, 2020, were assessed. Information including age, sex, GBCA type, onset, and severity of HSRs was retrospectively analyzed. Results Among the 331070 cases of GBCA exposure in 154539 patients, 1304 cases of HSRs (0.4%) were reported. Acute HSRs accounted for 1178 cases (0.4%), while 126 cases (0.04%) were delayed HSRs. While both premedication (odds ratio [OR] = 0.7, P = .041) and changing the type of GBCA (OR = 0.2, P < .001) showed preventative effects in patients with a history of acute HSRs, only premedication (OR = 0.2, P = .016) significantly reduced the incidence of HSRs in patients with a history of delayed reactions. The risk of an HSR to GBCA was higher in those with a history of an HSR to iodinated contrast media (OR = 4.6, P < .001). Conclusion The rate of hypersensitivity reactions (HSRs) to gadolinium-based contrast agents (GBCAs) was 0.4%. The absence of premedication, repeated exposures to the culprit GBCA, and a history of HSRs to iodinated contrast media and GBCAs were risk factors for HSRs to GBCAs. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Kallmes and McDonald in this issue.

Analysis of Breakthrough Reactions in 1,143 Desensitization Procedures in a Single Tertiary Hospital Using a One-Bag Desensitization Protocol

Background

Drug desensitization is helpful for patients who have experienced significant hypersensitivity reactions (HSRs) to antineoplastic agents. One-bag desensitization protocols, attracting attention in recent years, need to be validated on their safety and efficacy in a large number.

Methods

One-bag desensitization procedures conducted from 2018 to 2020 were analyzed; their outcomes and the risk factors for breakthrough reactions (BTRs) were assessed in desensitization procedures to major drug types (platins, taxanes, and monoclonal antibodies).

Results

A total of 1,143 procedures of one-bag desensitization were performed in 228 patients with 99% completion rate. BTRs occurred in 26% of the total desensitization procedures—34% in platins, 12% in taxanes, and 18% in mAbs. BTR occurrence rate decreased along the desensitization process with 80% of BTRs occurring within the 6th desensitization attempts. Severe BTR occurred more frequently with severe initial HSRs (1% in mild to moderate initial HSRs vs. 16% in severe). Severe initial HSR was also a significant risk factor for moderate to severe BTR in platins (odds ratio 1.56, 95% confidence interval [CI] 1.06–2.29, p = 0.025). The use of steroid was also associated with lower occurrence of moderate to severe BTR (odds ratio 0.50, 95% CI 0.35–0.72, p < 0.001).

Conclusion

Most patients with HSRs to antineoplastic agents can safely receive chemotherapy through a one-bag desensitization protocol. Further studies on each drug with larger sample size can help verify the risk factors of BTRs and evaluate the efficacy of steroid premedication in improving the safety of desensitization in high-risk patients.

Incidence and risk factors of late adverse reactions to low-osmolar contrast media: A prospective observational study of 10,540 exposures

PURPOSE

To evaluate the incidence and risk factors of late adverse reactions (ARs) to non-ionic low-osmolar contrast media (LOCM).

METHODS

The occurrence of late AR was monitored on day 1 and from day 7 to day 28 in all patients who received enhanced computed tomography using LOCM during a 5-week study period in a single tertiary hospital. Patients who experienced late AR were followed up for three years.

RESULTS

Among the total 10,540 LOCM exposures, 315 ARs (3.0%) were reported; acute ARs occurred in 108 LOCM exposures (1.0%) and late ARs occurred in 207 LOCM exposures (2.0%) (90.9% within one week, 9.1% developed afterwards by day 20). Previous history of drug allergy (odds ratio [OR] = 4.59; 95% confidence interval [CI] 2.17-9.71) and allergic diseases (OR = 2.54; 95% CI 1.32-4.91) were risk factors of late ARs to LOCM. Although the recurrence rate was lowered with premedication from 8.5% to 1.7% (8/94 vs. 3/178; p = 0.016), LOCM change did not make difference compared to reuse of the culprit LOCM (2/38 vs. 9/234; p = 0.655). In patients with a history of late AR to LOCM, the risk of recurrent reactions decreased with longer time intervals between exposures (OR = 0.86; 95% CI: 0.77-0.97; p = 0.025) and with the use of antihistamine premedication (OR = 0.27; 95% CI: 0.06-0.99; p = 0.049).

CONCLUSIONS

Late ARs to LOCM occurred mostly within one week. The use of premedication may be helpful in reducing the recurrence of late ARs.

Ultra-high-resolution computed tomography shows changes in the lungs related with airway hyperresponsiveness in a murine asthma model

In vivo presentation of airway hyper-responsiveness (AHR) at the different time points of the allergic reaction is not clearly understood. The purpose of this study was to investigate how AHR manifests in the airway and the lung parenchyma in vivo following exposure to different stimuli and in the early and late phases of asthma after allergen exposure. Ovalbumin (OVA)-induced allergic asthma model was established using 6-week female BALB/c mice. Enhanced pause was measured with a non-invasive method to assess AHR. The dynamic changes of the airway and lung parenchyma were evaluated with ultra-high-resolution computed tomography (128 multi-detector, 1024 × 1024 matrix) for 10 h. While the methacholine challenge showed no grossly visible changes in the proximal airway and lung parenchyma despite provoking AHR, the OVA challenge induced significant immediate changes manifesting as peribronchial ground glass opacities, consolidations, air-trapping, and paradoxical proximal airway dilatations. After resolution of immediate response, multiple episodes of AHRs occurred with paradoxical proximal airway dilatation and peripheral air-trapping in late phase over a prolonged time period in vivo. Understanding of airflow limitation based on the structural changes of asthmatic airway would be helpful to make an appropriate drug delivery strategy for the treatment of asthma.

Light intensity dependence of organic solar cell operation and dominance switching between Shockley-Read-Hall and bimolecular recombination losses

We investigated the variation of current density-voltage (J-V) characteristics of an organic solar cell (OSC) in the dark and at 9 different light intensities ranging from 0.01 to 1 sun of the AM1.5G spectrum. All three conventional parameters, short-circuit currents (Jsc), open-circuit voltage (Voc), and Fill factor (FF), representing OSC performance evolved systematically in response to light intensity increase. Unlike Jsc that showed quasi-linear monotonic increase, Voc and FF showed distinctive non-monotonic variations. To elucidate the origin of such variations, we performed extensive simulation studies including Shockley-Read-Hall (SRH) recombination losses. Simulation results were sensitive to defect densities, and simultaneous agreement to 10 measured J-V curves was possible only with the defect density of [Formula: see text]. Based on analyses of simulation results, we were able to separate current losses into SRH- and bimolecular-recombination components and, moreover, identify that the competition between SRH- and bimolecular-loss currents were responsible for the aforementioned variations in Jsc, Voc, and FF. In particular, we verified that apparent demarcation in Voc, and FF variations, which seemed to appear at different light intensities, originated from the same mechanism of dominance switching between recombination losses.

Identifying different types of microorganisms with terahertz spectroscopy

Most microbial detection techniques require pretreatment, such as fluorescent labeling and cultivation processes. Here, we propose novel tools for classifying and identifying microorganisms such as molds, yeasts, and bacteria based on their intrinsic dielectric constants in the THz frequency range. We first measured the dielectric constant of films that consisted of a wide range of microbial species, and extracted the values for the individual microbes using the effective medium theory. The dielectric constant of the molds was 1.24-1.85, which was lower than that of bacteria ranging from 2.75-4.11. The yeasts exhibited particularly high dielectric constants reaching 5.63-5.97, which were even higher than that of water. These values were consistent with the results of low-density measurements in an aqueous environment using microfluidic metamaterials. In particular, a blue shift in the metamaterial resonance occurred for molds and bacteria, whereas the molds have higher contrast relative to bacteria in the aqueous environment. By contrast, the deposition of the yeasts induced a red shift because their dielectric constant was higher than that of water. Finally, we measured the dielectric constants of peptidoglycan and polysaccharides such as chitin, α-glucan, and β-glucans (with short and long branches), and confirmed that cell wall composition was the main cause of the observed differences in dielectric constants for different types of microorganisms.

Light Intensity-dependent Variation in Defect Contributions to Charge Transport and Recombination in a Planar MAPbI3 Perovskite Solar Cell

We investigated operation of a planar MAPbI₃ solar cell with respect to intensity variation ranging from 0.01 to 1 sun. Measured J-V curves consisted of space-charge-limited currents (SCLC) in a drift-dominant range and diode-like currents in a diffusion-dominant range. The variation of power-law exponent of SCLC showed that charge trapping by defects diminished as intensity increased, and that drift currents became eventually almost ohmic. Diode-like currents were analysed using a modified Shockley-equation model, the validity of which was confirmed by comparing measured and estimated open-circuit voltages. Intensity dependence of ideality factor led us to the conclusion that there were two other types of defects that contributed mostly as recombination centers. At low intensities, monomolecular recombination occurred due to one of these defects in addition to bimolecular recombination to result in the ideality factor of ~1.7. However, at high intensities, another type of defect not only took over monomolecular recombination, but also dominated bimolecular recombination to result in the ideality factor of ~2.0. These ideality-factor values were consistent with those representing the intensity dependence of loss-current ratio estimated by using a constant internal-quantum-efficiency approximation. The presence of multiple types of defects was corroborated by findings from equivalent-circuit analysis of impedance spectra.

Increasing the sensitivity of terahertz split ring resonator metamaterials for dielectric sensing by localized substrate etching

We demonstrate a significant enhancement in the sensitivity of split ring resonator terahertz metamaterial dielectric sensors by the introduction of etched trenches into their inductive-capacitive gap area, both through finite element simulations and in experiments performed using terahertz time-domain spectroscopy. The enhanced sensitivity is demonstrated by observation of an increased frequency shift in response to overlaid dielectric material of thicknesses up to 18 µm deposited on to the sensor surface. We show that sensitivity to the dielectric is enhanced by a factor of up to ∼2.7 times by the incorporation of locally etched trenches with a depth of ∼3.4 µm, for example, and discuss the effect of the etching on the electrical properties of the sensors. Our experimental findings are in good agreement with simulations of the sensors obtained using finite element methods.

Strain Engineering of the Berry Curvature Dipole and Valley Magnetization in Monolayer MoS_{2}

The Berry curvature dipole is a physical quantity that is expected to allow various quantum geometrical phenomena in a range of solid-state systems. Monolayer transition metal dichalcogenides provide an exceptional platform to modulate and investigate the Berry curvature dipole through strain. Here, we theoretically demonstrate and experimentally verify for monolayer MoS_{2} the generation of valley orbital magnetization as a response to an in-plane electric field due to the Berry curvature dipole. The measured valley orbital magnetization shows excellent agreement with the calculated Berry curvature dipole, which can be controlled by the magnitude and direction of strain. Our results show that the Berry curvature dipole acts as an effective magnetic field in current-carrying systems, providing a novel route to generate magnetization.

Humidity sensing using THz metamaterial with silk protein fibroin

In this study, we developed hybrid humidity sensing methods by incorporating silk fibroin protein onto metamaterials, operating in the terahertz (THz) frequencies; the resonant frequency shifted but saturated at a specific thickness due to the limited sensing volume of the metamaterial. From the saturated value, we extracted the dielectric constant for the silk films. We also observed additional resonance shifts when we applied humid air to silk-coated metamaterials, due to the increased water molecule numbers on the film. Frequency shifts depend linearly on relative humidity. Also, in situ THz spectroscopy measurements reveal that the time response is instantaneous within our detection limit, especially upon exposure to humid air, whereas the small slowly decaying component appeared when we applied dry air. The time taken by the slow component in the drying process was 10-50 s, depending on film thickness. This could optimize humidity sensors as a fast and efficient detection tool to measure air humidity.

Enhanced sensitivity in THz plasmonic sensors with silver nanowires

We developed hybrid slot antenna structures for microbial sensing in the THz frequency range, where silver nanowires (AgNWs) were employed to increase the sensitivity. In order to fabricate the hybrid devices, we partially etched the AgNW in the slot antenna region, where we can expect the field enhancement effect at the AgNW tip. We measured the resonant-frequency shift observed upon the deposition of a polymer layer, and observed that the sensitivity increased upon the introduction of AgNWs, with an enhancement factor of more than four times (approximately six times in terms of figure-of-merit). The sensitivity increased with the AgNW density until saturation. In addition, we tested devices with PRD1 viruses, and obtained an enhancement factor of 3.4 for a slot antenna width of 3 μm. Furthermore, we performed finite-difference time-domain simulations, which confirmed the experimental results. The sensitivity enhancement factor decreased with the decrease of the slot width, consistent with the experimental findings. Two-dimensional mapping of the electric field confirmed the strong field localization and enhancement at the AgNW tips.

Brain Transplantation of Neural Stem Cells Cotransduced with Tyrosine Hydroxylase and GTP Cyclohydrolase 1 in Parkinsonian Rats

Neural stem cells (NSCs) of the central nervous system (CNS) recently have attracted a great deal of interest not only because of their importance in basic research on neural development, but also in terms of their therapeutic potential in neurological diseases, such as Parkinson's disease (PD). To examine if genetically modified NSCs are a suitable source for the cell and gene therapy of PD, an immortalized mouse NSC line, C17.2, was transduced with tyrosine hydroxylase (TH) gene and with GTP cyclohydrolase 1 (GTPCH1) gene, which are important enzymes in dopamine biosynthesis. The expression of TH in transduced C17.2-THGC cells was confirmed by RT-PCR, Western blot analysis, and immunocytochemistry, and expression of GTPCH1 by RT-PCR. The level of L-DOPA released by C17.2-THGC cells, as determined by HPLC assay, was 3793 pmol/106 cells, which is 760-fold higher than that produced by C17.2-TH cells, indicating that GTPCH1 expression is important for L-DOPA production by transduced C17.2 cells. Following the implantation of C17.2-THGcC NSCs into the striata of parkinsonian rats, a marked improvement in amphetamine-induced turning behavior was observed in parkinsonian rats grafted with C17.2-THGC cells but not in the control rats grafted with C17.2 cells. These results indicate that genetically modified NSCs grafted into the brain of the parkinsonian rats are capable of survival, migration, and neuronal differentiation. Collectively, these results suggest that NSCs have great potential as a source of cells for cell therapy and an effective vehicle for therapeutic gene transfer in Parkinson's disease.

Crystallization Kinetics of Lead Halide Perovskite Film Monitored by In Situ Terahertz Spectroscopy

Vibrational modes in the terahertz (THz) frequency range are good indicators of lead halide perovskite's crystallization phase. We performed real-time THz spectroscopy to monitor the crystallization kinetics in the perovskite films. First, THz absorptance was measured while the perovskite film was annealed at different temperatures. By analyzing the Avrami exponent, we observed an abrupt dimensionality switch (from 1D to 2D) with increasing temperature starting at approximately 90 °C. We also monitored the laser-induced crystallinity enhancement of the preannealed perovskite film. The THz absorptance increased initially, then subsequently decayed over a couple of hours, although the enhancement factor varies depending on the film crystallinity. In particular, the Avrami analysis implied that the light-induced crystallization was assisted by the 1D diffusion processes. The activation photon energy was measured at 2.3 eV, which indicated that enhanced crystallization originated from the photoinduced structural change of residual lead iodide at the grain boundary.

Suspended single-walled carbon nanotube fluidic sensors

In this paper, we demonstrate the fabrication of liquid flow sensors employing partially suspended single-walled carbon nanotubes (SWNTs). We have found that the sign of the conductance change in SWNT flow sensors is not influenced by the direction of water flow for both supported and suspended devices. Therefore, the streaming potential is not the principal mechanism of the SWNT sensor response. Instead, the conductance change is more likely due to a reduction in the cation density in the electrical double layer, whose equilibrium conditions are determined by the liquid flow rate. More importantly, we have found that the sensitivity of suspended SWNT devices is more than 10 times greater than that of supported SWNT devices. A reduced screening effect and an increase in effective sensing volume are responsible for the enhanced sensitivity, which is consistent with the ion depletion model. We also have measured conductance as a function of gate bias at different flow rates and have determined the flow-rate dependent effective charge density, which influences the electrostatic configuration around SWNT devices.

Non-Contact Local Conductance Mapping of Individual Graphene Oxide Sheets during the Reduction Process

We used electrostatic force microscopy (EFM) to investigate local conducting states of atomically thin individual graphene oxide (GO) sheets and monitor the spatial evolution of their conducting properties during the reduction process. Because of the thinness of the GO sheets and finite carrier density, the electric field is partially screened in the reduced GO, which is manifested in the EFM phase signals. We found inhomogeneous oxidation states in as-prepared GO sheets and followed the evolution of reduction process in the individual GO sheets during both thermal and chemical reduction. We also compared the EFM measurement results with simultaneous IV characteristics to assess correlations between two measurements.

Sensitive detection of yeast using terahertz slot antennas

We demonstrated sensitive detection of individual yeast cells and yeast films by using slot antenna arrays operating in the terahertz frequency range. Microorganisms located at the slot area cause a shift in the resonant frequency of the THz transmission. The shift was investigated as a function of the surface number density for a set of devices fabricated on different substrates. In particular, sensors fabricated on a substrate with relatively low permittivity demonstrate higher sensitivity. The frequency shift decreases with increasing slot antenna width for a fixed coverage of yeast film, indicating a field enhancement effect. Furthermore, the vertical range of the effective sensing volume has been studied by varying the thickness of the yeast film. The resonant frequency shift saturates at 3.5 μm for a slot width of 2 μm. In addition, the results of finite-difference time-domain simulations are in good agreement with our experimental data.

Charge transport in light emitting devices based on colloidal quantum dots and a solution-processed nickel oxide layer

We fabricated hybrid light emitting devices based on colloidal CdSe/ZnS core/shell quantum dots and a solution-processed NiO layer. The use of a sol-gel NiO layer as a hole injection layer (HIL) resulted in overall improvement in device operation compared to a control device with a more conventional poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) HIL. In particular, luminous efficiency increased substantially because of the suppression of excessive currents and became as large as 2.45 cd/A. To manifest the origin of current reduction, temperature- and electric field-dependent variations of currents with respect to bias voltages were investigated. In a low bias voltage range below the threshold for luminance turn-on, the Poole-Frenkel (PF) emission mechanism was responsible for the current-density variation. However, the space-charge-limited current modified with PF-type mobility ruled the current-density variation in high bias voltage range above the threshold.

Detection of microorganisms using terahertz metamaterials

Microorganisms such as fungi and bacteria cause many human diseases and therefore rapid and accurate identification of these substances is essential for effective treatment and prevention of further infections. In particular, contemporary microbial detection technique is limited by the low detection speed which usually extends over a couple of days. Here we demonstrate that metamaterials operating in the terahertz frequency range shows promising potential for use in fabricating the highly sensitive and selective microbial sensors that are capable of high-speed on-site detection of microorganisms in both ambient and aqueous environments. We were able to detect extremely small amounts of the microorganisms, because their sizes are on the same scale as the micro-gaps of the terahertz metamaterials. The resonant frequency shift of the metamaterials was investigated in terms of the number density and the dielectric constants of the microorganisms, which was successfully interpreted by the change in the effective dielectric constant of a gap area.

Factors affecting unmet healthcare needs of older people in Korea

BACKGROUND

Despite the fact that the National Health Insurance programmes have ensured universal coverage for Koreans, disparities in access to health care and unmet healthcare needs still exist in Korea.

AIM

The purpose of this study was to analyse factors affecting unmet healthcare needs of older people in Korea.

METHODS

This study had a cross-sectional, descriptive design using secondary data taken from the Korean National Health and Nutrition Survey conducted in 2007-2009. A complex sampling design was used, and the participants included a nationally representative sample of 3943 people older than 64 years. Socio-demographic variables, subjective health, existence of chronic diseases, quality of life and unmet healthcare needs were included in the study instruments. Logistic regression analyses were performed in order to examine the relationship between unmet healthcare needs and independent variables.

RESULTS

According to the results, 29.4% of older women and 14.0% of older men had not visited clinics or hospitals when they needed to obtain healthcare services (unmet healthcare needs) during the past 12 months. Older women [odds ratio (OR) = 1.831, 95% confidence interval (CI) = 1.428-2.347] and those with poor subjective health (OR = 1.708, 95% CI = 1.371-2.126) and arthritis (OR = 1.278, 95% CI = 1.029-1.586) were more likely to have unmet healthcare needs than their counterparts.

CONCLUSIONS

Efforts to decrease unmet healthcare needs, targeting high-risk groups (especially for older women), are needed in order to prevent disability, decrease mortality and promote the quality of life of older people.

Terahertz conductivity of reduced graphene oxide films

We performed time-domain terahertz (THz) spectroscopy on reduced graphene oxide (rGO) network films coated on quartz substrates from dispersion solutions by spraying method. The rGO network films demonstrate high conductivity of about 900 S/cm in the THz frequency range after a high temperature reduction process. The frequency-dependent conductivities and the refractive indexes of the rGO films have been obtained and analyzed with respect to the Drude free-electron model, which is characterized by large scattering rate. Finally, we demonstrate that the THz conductivities can be manipulated by controlling the reduction process, which correlates well with the DC conductivity above the percolation limit.

Adenovirus-mediated overexpression of Tcfe3 ameliorates hyperglycaemia in a mouse model of diabetes by upregulating glucokinase in the liver

AIMS/HYPOTHESIS

Transcription factor E3 (TFE3) has been shown to increase insulin sensitivity by activating insulin-signalling pathways. However, the role of TFE3 in glucose homeostasis is not fully understood. Here, we explored the possible therapeutic potential of TFE3 for the control of hyperglycaemia using a streptozotocin-induced mouse model of diabetes.

METHODS

We achieved overabundance of TFE3 in streptozotocin mice by administering an adenovirus (Ad) or adeno-associated virus serotype 2 (AAV2). We also performed an oral glucose tolerance test (OGTT) and insulin tolerance test (ITT). To explore molecular mechanisms of blood glucose control by TFE3, transcriptional studies on the regulation of genes involved in hepatic glucose metabolism were performed using quantitative real-time PCR and chromatin immunoprecipitation assay. The binding site of TFE3 in the liver Gck gene promoter was identified using deletion and site-specific mutation studies.

RESULTS

Overabundance of TFE3 resulted in reduced hyperglycaemia as shown by the OGTT and ITT in streptozotocin-treated mice. We observed that TFE3 can upregulate Gck in a state of insulin deficiency. However, glucose-6-phosphatase and cytosolic phosphoenolpyruvate carboxykinase mRNA levels were decreased by Ad-mediated overexpression of Tcfe3. Biochemical studies revealed that the anti-hyperglycaemic effect of TFE3 is due to the upregulation of Gck. In primary cultured hepatocytes, TFE3 increased expression of Gck mRNA. Conversely, small interfering RNA-mediated knockdown of TFE3 resulted in a decrease in Gck mRNA.

CONCLUSIONS/INTERPRETATION

This study demonstrates that TFE3 counteracts hyperglycaemia in streptozotocin-treated mice. This effect could be due to the upregulation of Gck by binding of TFE3 to its cognitive promoter region.

Diffusion Length in Nanoporous Photoelectrodes of Dye-Sensitized Solar Cells under Operating Conditions Measured by Photocurrent Microscopy

We determined the carrier diffusion lengths in nanoporous layers of dye-sensitized solar cells by using scanning photocurrent microscopy. The diffusion lengths were found to be 60-100 μm for the conventional cells. In addition, we found a correlation between the carrier diffusion lengths and the cell efficiency, which proved that improvement in the diffusion length is one of the crucial factors for optimizing device performance. The diffusion length was measured for various operating conditions by varying parameters such as solar light intensity and applied electrical voltage. In particular, we observed electric-field-driven, carrier transport phenomena (i.e., drift current) in modified cells. Fitting with the drift-diffusion model enabled us to extract the electric field strengths present in the TiO2 nanoporous layer.

Transfer-printing of as-fabricated carbon nanotube devices onto various substrates

Exact replicas of carbon nanotube devices as fabricated on SiO(2) /Si substrates are prepared on various non-conventional substrates such as nonplanar or soft substrates by a simple, yet versatile, transfer-printing "cut-and-paste" method. In this way, harsh growth and fabrication processes can be minimized on the target substrates. The electrical characteristics of transfer-printed devices are compared to those of original devices.

Anomalous band formation in arrays of terahertz nanoresonators

We investigate band formation in one-dimensional periodic arrays of rectangular holes which have a nanoscale width but a length of 100 μm. These holes are tailored to work as resonators in the terahertz frequency regime. We study the evolution of the electromagnetic response with the period of the array, showing that this dependence is not monotonic due to both the oscillating behavior of the coupling between holes and its long-range character.

Vertical growth and resonator properties of hexagonally shaped zinc oxide nanonails

We synthesized vertically aligned nail-shaped ZnO nanocrystal arrays on silicon substrates via a combination of a carbothermal reduction method and textured ZnO seeding layers that were precoated on silicon substrates by thermally decomposing zinc acetate, and studied their optical properties using cathodoluminescence (CL) and photoluminescence techniques. The ZnO nanonails show a sharp band-gap edge UV emission and a defect-related broad green emission. Monochromatic CL images of an individual ZnO nanonail show variations in spatial distributions of respective CL bands that had different origins. We attribute the spatial variation of CL images to an uneven distribution of luminescent defects and/or a structure-related light out-coupling from hexagonal ZnO nanostructures. The most distinct CL feature from the hexagonal head of an individual ZnO nanonail was the occurrence of a series of distinct resonant peaks within the visible wavelength range. It appeared that the head of a nanonail played the role of a hexagonal cavity so that polarization-dependent whispering gallery modes were stimulated by electron beam excitation.

Electron beam induced current measurements on single-walled carbon nanotube devices

We report on electron beam induced current (EBIC) from individual carbon nanotubes (CNTs) which are in contact with metal electrodes. The EBIC signals originate from the diffusion of excess carriers induced by the electron beam bombardment. The EBIC image enables us to locate the individual CNTs efficiently. From the polarity of the EBIC signals we can identify the electrical contacts to the metal electrodes. More importantly, we demonstrate that the EBIC can be used to characterize the local electrical properties of CNT-based devices, such as asymmetry in metal contacts and the presence of defects. EBIC is also observed regardless of the presence of insulating surfaces, indicating that the EBIC is a result of the direct interaction between the CNTs and the electron beams.

Hybrid light-emitting diodes based on flexible sheets of mass-produced ZnO nanowires

We report the production of free-standing thin sheets made up of mass-produced ZnO nanowires and the application of these nanowire sheets for the fabrication of ZnO/organic hybrid light-emitting diodes in the manner of assembly. Different p-type organic semiconductors are used to form heterojunctions with the ZnO nanowire film. Electroluminescence measurements of the devices show UV and visible emissions. Identical strong red emission is observed independent of the organic semiconductor materials used in this work. The visible emissions corresponding to the electron transition between defect levels within the energy bandgap of ZnO are discussed.

Uncovering operational mechanisms of a single-walled carbon nanotube network device using local probe electrical characterizations

The apparent field-effect-transistor (FET)-like operations of a device based on a network of single-walled carbon nanotubes (SWCNTs) are elucidated with the help of local probe electrical characterization methods using an atomic force microscope. The apparent switching behavior of the device with an on-off ratio>10(4) is found to be due to just two localized areas in the network of SWCNTs based on the measurements by electrostatic force microscopy and scanning gate microscopy. The result demonstrates that the conductance of a network of SWCNTs can be dominated by localized perturbations.

Terahertz near-field enhancement in narrow rectangular apertures on metal film

We report huge field accumulations in rectangular aperture arrays on thin metal film by using shape resonance in THz frequency region. A huge far-field transmission enhancement is observed in samples of various widths ranging from 10 mum to 1.8 mum which correspond to only an order of lambda/100. Theoretical calculations based on vector diffraction theory indicates 230 times near-field enhancement in case of the 1.8 mum wide rectangular aperture. Transmission measurement through the single rectangular aperture shows that the shape resonance, not the periodicity, is mainly responsible for the transmission enhancement and the corresponding field enhancement.

Imaging of photocurrent generation and collection in single-layer graphene

Unlike in linear nanostructures, photocurrent generated in single-layer graphene (SLG) is expected to display two-dimensional characteristics. This allows the investigation of carrier dynamics, in relation to several spatially varying factors (such as the location of photocurrent generation and collection) and the overall electron band configuration of the SLG. In this letter, we use scanning photocurrent microscopy to investigate the spatial mapping of photocurrent generation and collection in SLG in a multielectrode geometry. A strong electric field near metal-graphene contacts leads to efficient photocurrent generation, resulting in >30% efficiency for electron-hole separation. The polarity and magnitude of contact photocurrent are used to study the band alignment and graphene electrical potential near contacts, from which it is shown that there exist large-scale spatial variations in graphene electric potential. Our measurements with a multielectrode device configuration reveal that photocurrent is distributed with a clear directional dependence among different collector electrodes. In the same measurement scheme, we also determine the majority carrier in graphene under different gate conditions by imaging the thermocurrent generated by laser-induced heating of electrodes.

Enhancement of recombinant erythropoietin production in CHO cells in an incubator without CO(2) addition

The effect of low levels of carbon dioxide (CO(2)) in the gas phase on the production of recombinant human erythropoietin (EPO)in CHO cells was explored. A T-flask culture in an incubator without CO(2) addition showed a slow cell growth initially followed by the cessation of growth, while other cultures incubated under 0.5-5% CO(2) concentrations grew normally at the same rate during the entire period of cultivation. Interestingly, the production of EPO in the culture incubated under no CO(2) supply was highest among the tested cultures. The cell specific secretion rate of EPO (q(EPO)) of the culture under no CO(2) supply was about 3 times higher than that of the culture under 5% CO(2) supply. Western blot analysis and in vivo bioassay of EPO showed no apparent changes in EPO quality between the two cases of different CO(2) environments (air vs. 5% CO(2)), suggesting robust glycosylation of EPO by CHO cells even under very reduced CO(2) environment. Various combinations of the two extreme cases, with 5% CO(2) supply (suitable for cell growth) and no CO(2) addition (better for EPO production), were made in order to maximize the volumetric productivity of EPO secretion (P(V)) in CHO cells. The P(V) of the cultures programmed with initial incubation under 5% CO(2) followed by no CO(2) supply was about 2 times superior to that of the culture incubated only under no CO(2) supply. The P(V) of the culture under no CO(2) supply was slightly lower than that of culture grown under 5% CO(2). However, the q(EPO) of the no CO(2) supply case was more than 5 times higher than that of the culture under 5% CO(2) supply. In conclusion, we have demonstrated that a simple programming of CO(2) supply to an incubator can enhance the production of EPO in CHO cells remarkably, without any apparent change of the EPO quality.

Bending and bundling of metal-free vertically aligned ZnO nanowires due to electrostatic interaction

Bending and bundling was observed from vertically aligned arrays of ZnO nanowires with flat (0001) top surfaces, which were synthesized using a vapor-phase method without metal catalysts. Sufficient evidence was found to exclude electron-beam bombardment during scanning electron microscopy as a cause for bending and bundling. We attribute the bending and bundling to electrostatic interactions due to charged (0001) polar surfaces, and also discussed the threshold surface charge densities for the bending and bundling based on a simple cantilever-bending model. Some growth features were indicative of the operation of electrostatic interactions during the growth.

Advanced H2O2 oxidation for diethyl phthalate degradation in treated effluents: effect of nitrate on oxidation and a pilot-scale AOP operation

One of the objectives of this study was to delineate the effect of nitrate on diethyl phthalate (DEP) oxidation by conducting a bench-scale ultraviolet (UV)/H2O2 and O3/H2O2 operations as suggested in a previous study. We also aim to investigate DEP oxidation at various UV doses and H2O2 concentrations by performing a pilot-scale advanced oxidation processes (AOP) system, into which a portion of the effluent from a pilot-scale membrane bioreactor (MBR) plant was pumped. In the bench-scale AOP operation, the O3 oxidation alone as well as the UV irradiation without H2O2 addition could be among the desirable alternatives for the efficient removal of DEP dissolved in aqueous solutions at a low DEP concentration range of 85+/-15 microg/L. The adverse effect in the UV/H2O2 process was significantly greater than that in the UV oxidation alone, and its oxidation was almost halved by the nitrate. However, the nitrate clearly enhanced the DEP oxidation in the O3 oxidation and O3/H2O2 process. Especially, the addition of nitrate almost doubled the DEP oxidation efficiency in the O3/H2O2 process. The series of pilot-scale AOP operations confirmed that about 30-50% of DEP dissolved in the treated MBR effluent streams was, at least, oxidized by the O3 oxidation alone as well as the UV irradiation without H2O2 addition. The UV photolysis of H2O2 was most effective for DEP degradation with an H2O2 concentration of 40 mg/L at a UV dose of 500 mJ/cm2.

Photocurrent imaging of p-n junctions in ambipolar carbon nanotube transistors

We use scanning photocurrent microscopy (SPCM) to investigate the properties of internal p-n junctions in ambipolar carbon nanotube (CNT) transistors. Our SPCM images show strong signals near metal contacts whose polarity and positions change depending on the gate bias. SPCM images analyzed in conjunction with the overall conductance also indicate the existence and gate-dependent evolution of internal p-n junctions near contacts in the n-type operation regime. To determine the p-n junction position and the depletion width with a nanometer scale resolution, a Gaussian fit was used. We also measure the electric potential profile of partially suspended CNT devices at different gate biases, which shows that induced local fields can be imaged using the SPCM technique. Our experiment clearly demonstrates that SPCM is a valuable tool for imaging and optimizing electrical and optoelectronic properties of CNT based devices.

Autologous mesenchymal stem cell therapy delays the progression of neurological deficits in patients with multiple system atrophy

We evaluated the feasibility and safety of therapy with mesenchymal stem cells (MSCs) through consecutively intra-arterial and three repeated intravenous injections and compared the long-term prognosis between MSC-treated (n=11) and control multiple system atrophy (MSA) patients (n=18). The MSC-treated patients showed significantly greater improvement on the unified MSA rating scale (UMSARS) than the control patients at all visits throughout the 12-month study period. Orthostasis in UMSARS I items and cerebellar dysfunction-related items of UMSARS II items were significantly different in favor of MSC treatment compared to controls. Serial positron emission tomography scan in the MSC-treated group showed that increased fluorodeoxyglucose uptake from baseline was noted in cerebellum and frontal white matters. No serious adverse effects related to MSC therapy occurred. This study demonstrated that MSC therapy in patients with MSA was safe and delayed the progression of neurological deficits with achievement of functional improvement in the follow-up period.

Waste lime as a potential cation source in the phosphate crystallization process

In this study, the feasibility of waste lime as a potential cation source in phosphate crystallization process was investigated using laboratory scale up flow reactors, adopting sequencing batch type configuration. This research focused on its successful application in a novel sludge treatment process, which is comprised of a high performance fermenter (operating conditions: 55 degree C and pH 9) followed by a crystallization reactor. In the struvite precipitation test using synthetic wastewater, considerable nutrient removal (about 60%) in the form of ammonia and phosphate was observed within 0.5-1 hr of retention time, and only small amounts (< 5%) of ammonia stripping occurred naturally due to the alkaline (pH 9) characteristic of the feed substrate. By replacing the synthetic wastewater with the fermentation effluent, the optimal dosage of magnesium salt for struvite precipitation was 0.86 g Mg g(-1) P, similar to the mass ratio of the struvite. The optimal dosage of waste lime was 0.3 g 1(-1), resulting in 80 % of NH4-N and 41% of PO3-P removal, at about 3 hrs of retention time. Microscopic analysis showed that amorphous crystals were mainly observed in the settled solids with waste lime addition whereas prism-like crystals were found in the system with magnesium salt added. Mass balance analysis in full-scale model plants (Q=158,880 m(3)d(-1)) based on the present experimental results revealed that nutrient recycle loading from side stream to main liquid stream would be significantly reduced. The results of the experiment reveal that reuse of industrial waste lime in a nutrient recovery system has the various advantages such as higher economical benefits and sustainable treatment of the industrial waste.

A novel process for organic acids and nutrient recovery from municipal wastewater sludge

In this paper, a novel process for organic acids and nutrient recovery from municipal sludge was introduced and evaluated based on laboratory-scale studies. An economical estimation for its practical application was also performed by mass balance in a full-scale plant (Q=158,000 m3 d(-1)). This novel process comprises an upflow sludge blanket-type high performance elutriated acid fermenter (5d of SRT) for organic acids recovery followed by an upflow-type crystallisation (3 h of HRT) reactor using waste lime for nutrient recovery. In the system, the fermenter is characterised by thermophilic (55 degrees C) and alkaline conditions (pH 9), contributing to higher hydrolysis/acidogenesis (0.18 g VFA(COD) g(-1) VSS(COD), 63.3% of VFA(COD)/COD produced, based on sludge characteristics of the rainy season) and pathogen-free stabilised sludge production. It also provides the optimal condition for the following crystallisation reactor. In the process, the waste lime, which is an industrial waste, can be used for pH control and cation (Ca and Mg) sources for crystallisation reaction. A cost estimation for full-scale application demonstrates that this process has economic benefits (about 67 dollars per m3 of wastewater except for the energy expense) even in the rainy season.

Invisible plasmonic meta-materials through impedance matching to vacuum

We report on perfect transmission in two-dimensional plasmonic matamaterials in the terahertz frequency range, in which zeroth order transmittance becomes essentially unity near specific resonance frequencies. Perfect transmission may occur when the plasmonic metamaterials are perfectly impedance matched to vacuum, which is equivalent to designing an effective dielectric constant around epsilonr = -2. When the effective dielectric constant of the metamaterial is tuned towards epsilonr and the hole coverage is larger than 0.2, strong evanescent field builds up in the near field, making perfect transmission possible.

Antibacterial and antifungal activity of pinosylvin, a constituent of pine

The antibacterial and antifungal activities of pinosylvin (3,5-dihydroxy-trans-stilbene), a constituent of pine, were studied and compared with those of resveratrol (3,5,4'-trihydroxy-trans-stilbene). Pinosylvin exhibited more potent growth inhibitory activity against Candida albicans and Saccharomyces cerevisiae.

ANAMMOX and partial denitritation in anaerobic nitrogen removal from piggery waste

The anaerobic ammonium removal from a piggery waste with high strength (56 g COD/L and 5 g T-N/L) was investigated using a lab-scale upflow anaerobic sludge bed reactor at a mesophilic condition. Based on the nitrogen and carbon balance in the process, the contribution of autotrophic and heterotrophic organisms was also evaluated in terms of the influent NO2-N/NH4-N ratio (1:0.8 and 1:1.2 for Phase 1 and Phase 2, respectively). The result of this research demonstrates that the anaerobic ammonium removal from the piggery waste, using the UASB reactor, can be performed successfully. Furthermore, it appears that by using granular sludge as the seed biomass, the ANAMMOX reaction can start more quickly. Average nitrogen conversion was 0.59 kg T-N/m3 reactor-day (0.06 kg T-N/kg VSS/day) and 0.66 kg T-N/m3 reactor-day (0.08 kg T-N/kg VSS/day) for Phase 1 and Phase 2. The NO2-N/NH4-N removal ratio by the ANAMMOX was 1.48 and 1.79 for Phase 1 and Phase 2. The higher nitrite contents (about 50%) in the substrate resulted in higher nitrite nitrogen removal by the partial denitritation, as well as the ANAMMOX reaction, implying higher potential of partial denitritation. However, the result reveals that the ANAMMOX reaction was influenced less by the degree of partial denitritation, and the ANAMMOX bacteria did not compete with denitritation bacteria. The colour of the biomass at the bottom of the reactor changed from dark gray to dark red, which was accompanied by an increase in cytochrome content. At the end of the experiment, red-coloured granular sludge with diameter of 1-2 mm at the lower part of the reactor was also observed.

Municipal sludge management and disposal in South Korea: status and a new sustainable approach

Based on figures from 2002, 5216 ton/d of the municipal sludge is produced from 184 large municipal wastewater treatment plants in 111 cities with total treatment capacity of 19,229,745 m3/d. Even though the large amount of sludge disposal has depended greatly on ocean disposal and landfills until recently, the fraction of sludge reuse has gradually increased from 2.7% to 7%, since 1991. Due to a need of resources recovery from the sludge, high cost requirement of incineration and legislative regulation, recent new research is mainly focused on resources recovery and its reuse from the municipal sludge, such as high performance acid fermenter with pathogen reduction, crystallization (struvite and hydroxyapatite) using waste lime, cofermentation of municipal sludge with food waste, aerobic composting with P crystallization, vermistabilization, lime treatment, etc. Current research and practical activities with some efforts for the new technical development as well as environmental law and regulation are reviewed.