Application of air ions for bacterial de-colonization in air filters contaminated by aerosolized bacteria

We aerosolized the Escherichia coli (E. coli) and Staphylococcus epidermidis (S. epidermidis) bacteria and collected them on membrane filters. Then we generated air ions by applying a high voltage to a carbon fiber tip and applied them to the contaminated filters. The antibacterial efficiency was not significantly affected by the bacteria being Gram-positive or Gram-negative, however, negative ions showed a lower antibacterial efficiency than positive ions to both E. coli and S. epidermidis, even though the concentration of negative air ions was much higher than that of positive air ions. With a field emission scanning electron microscope (FE-SEM) images and fluorescence microscopy images using a LIVE/DEAD BacLight Bacterial Viability Kit, electrostatic disruption of the bacteria was found to be the dominant antibacterial effect.     

Advancing assessment and design of stormwater monitoring programs using a self-organizing map: characterization of trace metal concentration profiles in stormwater runoff

Stormwater runoff poses a great challenge to the scientific assessment of the effects of diffuse pollution sources on receiving waters. In this study, a self-organizing map (SOM), a research tool for analyzing specific patterns in a large array of data, was applied to the monitoring data obtained from a stormwater monitoring survey to acquire new insights into stream water quality profiles under different rainfall conditions. The components of the input data vectors used by the SOM included concentrations of 10 metal elements, river discharge, and rainfall amount which were collected at the inlet and endpoint of an urban segment of the Yeongsan River, Korea. From the study, it was found that the SOM displayed significant variability in trace metal concentrations for different monitoring sites and rainfall events, with a greater impact of stormwater runoff on stream water quality at the upstream site than at the downstream site, except under low rainfall conditions (≤4 mm). In addition, the SOM clearly determined the water quality characteristics for “non-storm” and “storm” data, where the parameters nickel and arsenic and the parameters chromium, cadmium, and lead played an important role in reflecting the spatial and temporal water quality, respectively. When the SOM was used to examine the efficacy of stormwater quality monitoring programs, between 34 and 64% of the sample size in the current data set was shown to be sufficient for estimating the stormwater pollutant loads. The observed errors were small, generally being below 10, 6, and 20% for load estimation, map resolution, and clustering accuracy, respectively. Thus, the method recommended may be used to minimize monitoring costs if both the efficiency and accuracy are further determined by examining a large existing data set.     

Possible association between nickel and chromium and oral cancer: a case-control study in central Taiwan

Oral cancer is one of the most common cancers in Taiwan. Changhua County, in central Taiwan, has an extremely high prevalence of oral cancer, along with a high concentration of metal-related industries and soil metal contamination. The aim of this study was to clarify the possible association between metals and oral cancer within this specific area. This study recruited 101 oral cancer patients and 104 controls from the Changhua Christian Hospital. All subjects completed a questionnaire that asked about demographic information; cigarette, alcohol, and betel quid use; and environmental and occupational exposure history. Blood samples were collected and tested for metal concentrations with inductively coupled plasma mass spectrometry. A multiple logistic regression model illustrated that oral cancer was significantly associated with the blood levels of nickel and chromium (both with P < 0.0001) after controlling for potential confounders. This study suggested a potential role of these two metals in the mechanism of oral cancer development.     

Effects of temperature steps on human skin physiology and thermal sensation response

Air-conditioning is frequently used as a means of adjusting indoor thermal environment in hot-and-humid areas. However, when entering an air-conditioned building from outdoors people may experience thermal discomfort and risk health consequence if the instantaneous change of air temperature exceeds the thermoregulatory capacity. A study was conducted to investigate the alteration in thermal perception and in thermoregulation that simultaneously occurred in response to temperature step in a thermal transient. In this study, two temperature down-steps from 32/28 to 24 °C and an up-step from 20 to 24 °C were created in a climatic chamber consisting of two microclimate-controlled rooms, and subjects were evaluated for change in thermal sensation as well as in skin physiological properties, including skin capillary blood flow (SCBF), skin moisture, transepidermal water loss (TEWL), and skin temperature over the course of acclimation. As the results show, a cold sensation overshot occurred in thermal sensation vote (TSV), skin temperature, and SCBF in 1 min after the temperature dropped from 32 to 24 °C. TSV correlated the best with skin temperature (r = 0.60) and moderately with skin moisture and TEWL (r = 0.42–0.54) when the temperature down-step reached 8 °C. TEWL acclimated in a two-stage pattern, demonstrating a difference between the sensational change and thermoregulation. The gender-specific influence occurred in thermoregulation but not in subjective sensation. The findings of the study suggest that thermoregulatory burden might be adequately controlled when the temperature step in thermal transition zone is limited to 4 °C or lower.     

巷道围岩破坏形式与原岩应力场的关系研究

运用东北大学开发的RFPA2D程序模拟原岩应力变化时巷道围岩破坏过程,了解无裂纹巷道围岩破坏形式与原岩应力的关系。根据模拟结果,在垂直应力大于水平应力的情况下,破坏主要在巷道侧面上发生。反之,在巷道顶板和底板发生。2个应力之比越大,这样的现象越明显。2个应力相同的情况下,在巷道顶底板和两帮都发生破坏。因此巷道破坏形式与垂直水平应力之间的比值有关而与应力大小无关。     

Triarylamine-based dual-function coadsorbents with extended π-conjugation aryl linkers for organic dye-sensitized solar cells

Triarylamine-based dual-function coadsorbents containing a carboxylic acid acceptor linked by extended π-conjugation aryl linkers (e.g., phenylene: HC-A3, naphthalene: HC-A4 and anthracene: HC-A5) were newly designed and synthesized. They were used as coadsorbents in organic dye-sensitized solar cells (DSSCs) based on a porphyrin dye (hexyloxy-biphenyl-ZnP-CN-COOH (HOP)). For comparison, the π-conjugated phenyl linker (HC-A3) previously developed by our group was also used as a coadsorbent. The structural effects on the photophysical and electrochemical properties and DSSC performance were systematically investigated. As a result, the DSSCs based on HC-A4 and HC-5 displayed power conversion efficiencies (PCEs) of 8.2% and 5.1%, respectively, while the HC-A3-based DSSC achieved a PCE of 7.7%. In the case of HC-A4, both the short-circuit photocurrent densities (J_sc) and open-circuit voltages (V_oc) of DSSCs were simultaneously improved to a large extent due to the more effective prevention of π−π stacking of organic dye molecules and the better light-harvesting effect at short wavelengths. The HC-A5-based DSSC exhibited a much lower short-circuit current (J_sc) and open-circuit voltages (V_oc) compared to the HC-A4-based DSSC, due to the fact that the dihedral angle of the π-conjugated linkers was too high for electron injection into the TiO₂ conduction band (CB) level. This had a reduced effect on preventing the π−π stacking of dye molecules, resulting in lower J_sc and V_oc values.     

A Review of Three‐Dimensional Resistive Switching Cross‐Bar Array Memories from the Integration and Materials Property Points of View

Issues in the circuitry, integration, and material properties of the two‐dimensional (2D) and three‐dimensional (3D) crossbar array (CBA)‐type resistance switching memories are described. Two important quantitative guidelines for the memory integration are provided with respect to the required numbers of signal wires and sneak current paths. The advantage of 3D CBAs over 2D CBAs (i.e., the decrease in effect memory cell size) can be exploited only under certain limited conditions due to the increased area and layout complexity of the periphery circuits. The sneak current problem can be mitigated by the adoption of different voltage application schemes and various selection devices. These have critical correlations, however, and depend on the involved types of resistance switching memory. The problem is quantitatively dealt with using the generalized equation for the overall resistance of the parasitic current paths. Atomic layer deposition is discussed in detail as the most feasible fabrication process of 3D CBAs because it can provide the device with the necessary conformality and atomic‐level accuracy in thickness control. Other subsidiary issues related to the line resistance, maximum available current, and fabrication technologies are also reviewed. Finally, a summary and outlook on various other applications of 3D CBAs are provided.     

Dissolution Behaviors and Applications of Silicon Oxides and Nitrides in Transient Electronics

Silicon oxides and nitrides are key materials for dielectrics and encapsulation layers in a class of silicon‐based high performance electronics that has ability to completely dissolve in a controlled fashion with programmable rates, when submerged in bio‐fluids and/or relevant solutions. This type of technology, referred to as “transient electronics”, has potential applications in biomedical implants, environmental sensors, and other envisioned areas. The results presented here provide comprehensive studies of transient behaviors of thin films of silicon oxides and nitrides in diverse aqueous solutions at different pH scales and temperatures. The kinetics of hydrolysis of these materials depends not only on pH levels/ion concentrations of solutions and temperatures, but also on the morphology and chemistry of the films, as determined by the deposition methods and conditions. Encapsulation strategies with a combination of layers demonstrate enhancement of the lifetime of transient electronic devices, by reducing water/vapor permeation through the defects.     

Highly Improved Sb2S3 Sensitized‐Inorganic–Organic Heterojunction Solar Cells and Quantification of Traps by Deep‐Level Transient Spectroscopy

The light‐harvesting Sb₂S₃ surface on mesoporous‐TiO₂ in inorganic–organic heterojunction solar cells is sulfurized with thioacetamide (TA). The photovoltaic performances are compared before and after TA treatment, and the state of the Sb₂S₃ is investigated by X‐ray diffraction, X‐ray photoelectron spectroscopy, and deep‐level transient spectroscopy (DLTS). Although there are no differences in crystallinity and composition, the TA‐treated solar cells exhibit significantly enhanced performance compared to pristine Sb₂S₃‐sensitized solar cells. From DLTS analysis, the performance enhancement is mainly attributed to the extinction of trap sites, which are present at a density of (2–5) × 10¹⁴ cm^?3 in Sb₂S₃, by TA treatment. Through such a simple treatment, the cell records an overall power conversion efficiency (PCE) of 7.5% through a metal mask under simulated illumination (AM 1.5G, 100 mW cm^–2) with a very high open circuit voltage of 711.0 mV. This PCE is, thus far, the highest reported for fully solid‐state chalcogenide‐sensitized solar cells.     

Balanced RF Duplexer with Low Interference Using Hybrid BAW Resonators for LTE Application

A balanced RF duplexer with low interference in an extremely narrow bandgap is proposed. The Long‐Term Evolution band‐7 duplexer should be designed to prevent the co‐existence problem with the WiFi band, whose fractional bandgap corresponds to only 0.7%. By implementing a hybrid bulk acoustic wave (BAW) structure, the temperature coefficient of frequency (TCF) value of the duplexer is successfully reduced and the suppressed interference for the narrow bandgap is performed. To achieve an RF duplexer with balanced Rx output topology, we also propose a novel balanced BAW Rx topology and RF circuit block. The novel balanced Rx filter is designed with both lattice‐ and ladder‐type configurations to ensure excellent attenuation. The RF circuit block, which is located between the antenna and the Rx filter, is developed to simultaneously function as a balance‐to‐unbalance transformer and a phase shift network. The size of the fabricated duplexer is as small as 2.0 mm × 1.6 mm. The maximum insertion loss of the duplexer is as low as 2.4 dB in the Tx band, and the minimum attenuation in the WiFi band is as high as 36.8 dB. The TCF value is considerably lowered to ?16.9 ppm/°C.