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To study the effect of rainfall patterns on diatom communities in four major central western streams on the Korean Peninsula during the monsoon seasons of 2013 through 2015, we measured precipitation, environmental factors, and epilithic diatoms at 42 sites before (May) and after (August and September) each monsoon. The Mangyeonggang river and Sapgyocheon stream (SS) had a high percentage of low-permeability soil, and the stream had the highest proportion (49.1%) of surrounding land in urban areas. Precipitation and precipitation frequency was closely correlated with electrical conductivity and nutrients, and this was particularly evident in SS. Epilithic diatom abundance for the most abundant species as, Navicula minima, decreased in the stream in 2013 and 2014 and increased in 2015 when precipitation and precipitation frequency were low. This was not clearly distinguishable in the ecological characteristics of each watercourse’s indicator species, except in SS. The dynamic community index was highest in 2015 (ca. 5.50), and the annual changes in the index were clearly shown in SS. The precipitation pattern and the dynamic community index were negatively correlated (r = −0.026~−0.385), and the precipitation within 2 weeks (r = −0.480 for SS) before the second sampling and the frequency of 10 mm of precipitation were closely correlated in the stream (r = −0.450 for SS). The distribution of epilithic diatoms in the four watercourses is therefore affected by monsoon precipitation and precipitation frequency, and the dynamic community index is determined by soil characteristics and land use.

In this work, we attempt to figure out alkoxy-substitution effects on two kinds of well-known non-fullerene acceptors (NFAs), IDT-series and Y-series acceptors, by placing alkoxy side chains on the β-positions of the outer thiophene units. The resulting molecules, named IDTN-O and Y6-O, exhibit different properties compared to the original acceptors named IDTN and Y6. The HOMO and LUMO levels of IDTN-O are slightly upshifted at the same time, which causes a slightly higher open-circuit voltage (Voc) without sacrificing the short-circuit current density (Jsc) of the devices. J71:IDTN-O blend films can also achieve a better blend morphology due to the conformational locking effect and higher dipole moment induced by the alkoxy groups, which helps achieve a higher fill factor (FF). In addition, Y6-O exhibits significantly upshifted LUMO levels compared to Y6, leading to a high Voc of 0.95 V. PM6:Y6-O blend films can also maintain an optimal blend morphology through side-chain engineering, which leads to an excellent FF of 78.0%. As a result of alkoxy substitution, both IDTN-O and Y6-O-based devices can achieve better performances of 12.1% and 16.6% than IDTN and Y6-based devices (10.9% and 15.7%), which indicates that this is an effective method to optimize these two types of NFAs.

Summary The field of organic solar cells has seen rapid developments after the report of a high-efficiency (15.7%) small molecule acceptor (SMA) named Y6. In this paper, we design and synthesize a family of SMAs with an aromatic backbone identical to that of Y6 but with different alkyl chains to investigate the influence of alkyl chains on the properties and performance of the SMAs. First, we show that it is beneficial to use branched alkyl chains on the nitrogen atoms of the pyrrole motif of the Y6. In addition, the branching position of the alkyl chains also has a major influence on material and device properties. The SMA with 3rd-position branched alkyl chains (named N3) exhibits optimal solubility and electronic and morphological properties, thus yielding the best performance. Further device optimization using a ternary strategy allows us to achieve a high efficiency of 16.74% (and a certified efficiency of 16.42%).

Geosmin is a major concern in the management of water sources worldwide. Thus, we predicted concentration categories of geosmin at three different depths of lakes (i.e., surface, middle, and bottom), and analyzed relationships between geosmin concentration and factors such as phytoplankton abundance and environmental variables. Data were collected monthly from three major lakes (Uiam, Cheongpyeong, and Paldang lakes) in Korea from May 2014 to December 2015. Before predicting geosmin concentration, we categorized it into four groups based on the boxplot method, and multivariate adaptive regression splines, classification and regression trees, and random forest (RF) were applied to identify the most appropriate modelling to predict geosmin concentration. Overall, using environmental variables was more accurate than using phytoplankton abundance to predict the four categories of geosmin concentration based on AUC and accuracy in all three models as well as each layer. The RF model had the highest predictive power among the three SDMs. When predicting geosmin in the three water layers, the relative importance of environmental variables and phytoplankton abundance in the sensitivity analysis was different for each layer. Water temperature and abundance of Cyanophyceae were the most important factors for predicting geosmin concentration categories in the surface layer, whereas total abundance of phytoplankton exhibited relatively higher importance in the bottom layer.

River water quality and organisms have a very close relationship with the human living environment and health, so it is very important to ensure and maintain the ecological integrity of the aquatic ecosystem. In that sense, benthic diatoms have relatively little mobility, can explain the effects of long-term exposed pollution sources, and are very suitable indicator organisms for river ecosystem evaluation. Diatom ecologists have been developed various diatom indices to assess water quality and stream ecosystem over the world. However, they so far have insufficient identification of taxa, are strongly regional, and are difficult to apply as they are domestically. Unfortunately, there has not been developed an independent diatom index suitable for the Korean stream. Therefore, management of water quality and aquatic ecosystem suitable for domestic rivers can be made, and development or improvement of comprehensive multivariate diatom index for the integrated assessment of water quality and aquatic ecosystem is urgently needed.

A group of regioregular polymer acceptors is synthesized by polymerizing Y6 moieties with different linker units including thiophene, vinylene, 2,2'-bithiophene, and thieno[3,2-b]thiophene, and their optoelectrical properties and photovoltaic performances are studied systematically. It is found that the linker units have significant impacts on the backbone planarity, conjugation, and hence optoelectrical properties of polymer acceptors. The vinylene-based PYF-V-o polymer shows a smaller dihedral angle between the end groups and vinylene units and a more rigid polymer backbone, thus affording bathochromic absorption and better electron-transporting capacity. As a result, the PM6:PYF-V-o based all-polymer solar cells (all-PSCs) are able to achieve the highest power conversion efficiency of 16.4% with an unprecedented small voltage loss of 0.49 V. Moreover, the PM6:PYF-V-o blend exhibits good resistance to environmental stressors and the air-processed PM6:PYF-V-o cells can still maintain a high efficiency of 16.1%, which is the best air-processed all-PSC efficiency reported to date. This study provides the structural-property guidance that can be used to facilitate the development of polymer acceptors for all-PSCs.

State-of-art Y-series polymer acceptors are typically based on a mono-thiophene linker, which can cause some twisted molecular conformations and thus limit the performance of all-polymer solar cells (all-PSCs). Here, a high-performance polymer acceptor based on vinylene linkers is reported, which leads to surprising changes in the polymers' molecular conformations, optoelectronic properties, and enhanced photovoltaic performance. It is found that the polymer acceptors based on thiophene or bithiophene linkers (PY-T-γ and PY-2T-γ) display significant molecular twisting between end-groups and linker units, while the vinylene-based polymer (PY-V-γ) exhibits a more coplanar and rigid molecular conformation. As a result, PY-V-γ demonstrates a better conjugation and tighter interchain stacking, which results in higher mobility and a reduced energetic disorder. Furthermore, detailed morphology investigations reveal that the PY-V-γ-based blend exhibits high domain purity and thus a better fill factor in its all-PSCs. With these, a higher efficiency of 17.1% is achieved in PY-V-γ-based all-PSCs, which is the highest efficiency reported for binary all-PSCs to date. This work demonstrates that the vinylene-linker is a superior unit to build polymer acceptors with more coplanar and rigid chain conformation, which is beneficial for polymer aggregation and efficient all-PSCs.

Many achnanthoid diatoms were transferred from Achnanthes or Achnanthidium to new genera based on characteristics observed via scanning electron microscopy (SEM). In this study, we isolated and cultured two Korean freshwater achnanthoid diatoms (Bacillariophyceae), studied their morphological characteristics using SEM, and assessed their molecular characteristics by analysing the nuclear small subunit (SSU) and ribulose-1,5-bisphosphate carboxylase/oxygenase (rbcL) genes. We emended the description of Lemnicola hungarica with regard to the spindly pore opening of the hymen and the internally convex occlusions of elongated pores on the mantle. In addition, we demonstrated that the valves of L. hungarica are occasionally biseriate to uniseriate towards the valve edge. A morphological comparison of Lemnicola strains and species showed that biseriate rows of areolae are no longer an essential characteristic for allocation to Lemnicola. Based on the SEM and molecular analysis results, we also established a new...

In the Korean Peninsula&rsquo, s southern estuaries, the distributive characteristics of epilithic diatoms and the important environmental factors predicting species occurrence were examined. The collection of diatoms and measurements of water quality and land-use were performed every May between 2009 and 2016, with no influence from the Asian monsoon and snow. Throughout the study, 564 diatoms were classified with first and second dominant species of Nitzschia inconspicua and N. perminuta. Based on diatom appearance and standing crops, the 512 sampling stations were divided into four groups by cluster analysis, and two regions, namely the West and East Sea. Geographically, G1, G2, G3, and G4 were located in the East Sea, Southeast Sea, West Sea, and Southwest Sea, respectively. Canonical correspondence analysis (CCA) results indicated that environmental factors, such as turbidity, electric conductivity (EC), and total phosphorus (TP), significantly influenced the distribution of epilithic diatoms. A random forest model showed that major environmental factors influencing the diatom species appearance included EC, salinity, turbidity, and total nitrogen. This study demonstrated that the spatial distribution of epilithic diatoms in the southern estuaries of the Korean Peninsula was determined by several factors, including a geographically higher tidal current-driven turbidity increase and higher industrial or anthropogenic nutrient-loading.

Titanium nitride (TIN) films were prepared by using rf magnetron sputtering technique. The films were deposited by a pure N2 plasma sputtering. Their mechanical properties, such as nanoindentation hardness, friction coefficient, and wettability have been investigated. XRD studies revealed that the orientation of TiN films changes toward the (111) orientation with decreasing working pressure due to a strong compressive stress during deposition . The strongest TiN(111) orientation is found when the film is deposited at working pressure of 1pa. This film shows a largest hardness of 15 GPa and a smallest friction coefficient of 0.17. This film was also found to be accompanied by a water-repellent surface with a water contact angle more than 100°

Two new benthic freshwater species belonging to the genus Achnanthidium were found in Korea. Achnanthidium ovale sp. nov. and A. cavitatum sp. nov. are described as new species based on light and scanning electron microscopy observations and molecular analyses. Both species are compared with the type material of morphologically similar taxa. Achnanthidium ovale differs from other species belonging to the A. pyrenaicum complex in outline, striation pattern, raphe central endings, and freestanding areolae at the apices. Achnanthidium cavitatum differs from other species in the A. minutissimum complex in outline, broad axial central area in the raphel ess valve, and slit-like areolae near the axial central area. We assessed their molecular characteristics by analyzing nuclear small subunit (SSU) rRNA and chloroplast-encoded rbcL gene sequences. Both the morphological comparison and the SSU and rbcL sequence analyses provide strong evidence to support the recognition of A. ovale and A. cavitatum as new species.

The water intake facility of Paldangho Lake (PIF), constructed in 1988, supplies drinking water to the Seoul metropolitan area and satellite city (ca. 20 million inhabitants) in South Korea. A nuisance cyanobacterial bloom (CB) has been observed every year in the PIF. Thus, related governments have been funding the control of CBs and algal-originated materials (AOMs). In this study, an algae-blocking mat (ABM) was developed to protect against CBs and AOMs considering temperature and water depth. We evaluated the daily and monthly performance of the ABM on phytoplankton, pH, dissolved oxygen, chlorophyll-a, and light intensity between April and October 2015. Although the average cell abundance of cyanobacteria between July and September approached the warning level of the Korea alert system, the highest algal removal efficiency was recorded as 92% in August when the cyanobacterial cells were over 66,000 cells/mL. On average, the ABM showed a low removal efficiency of 26% on both geosmin and 2-methylisoborneol, whereas total phytoplankton was more than 30%. In conclusion, our results indicate that the ABM may be an economical blocking tool for nuisance cyanobacteria in drinking water resources, considering AOMs and total phytoplankton.

Most of Korea&rsquo, s rivers and lakes are subject to physico-chemical disturbances, such as increased water quantity and flow rates, and influx of nitrogen and phosphorus, due to intense rainfall concentrated in the Asian monsoon season. To examine the influence of rainfall on epilithic diatom communities, we measured the diatom distribution and river water quality at 29 sites along the main-stream and tributaries of the Hantangang River, Korea, in the period of 2012&ndash, 2015. Water quality parameters in the polluted sites had improved following rainfall, but the response of dominant species varied with water quality, the dominant species Nitzschia fonticola decreased in abundance regardless of sampling sites, and the abundance of Achnanthidium minutissimum in the clean sites and Nitzschia palea in the polluted sites increased after rainfall, respectively. The community dynamic index (CDI) showed that the most obvious shift of epilithic diatom community occurred in the mid-polluted sites in 2013 with the highest rainfall. This suggest that the effect of rainfalls on the epilithic diatom community is dependent on various parameters, such as the magnitude of rainfall, water quality and its biotic compositions of diatom communities, but it also indicates that improving the water quality of rivers is important to promote the resilience of diatom communities to extremes of precipitation. Further investigation is needed to generalize the effects of monsoon rainfall on the epilithic diatom communities, considering rivers with different environmental characteristics.

Environmental factors and epilithic diatom communities in the lower streams near the harbor regionof South Korean peninsula were examined during no monsoon period in May 2013. The sampling of water andepilithic diatoms was conducted at both streams, 19 regulated streams(RS) that there are one or several damsconstructedin the river system, and 19 un-regulated streams(US) that there are no dams within the river. Acluster analysis based on the number of species and abundance of epilithic diatoms through the stations, dividedinto three groupssuch as groups I(mainly US), II(mixed with US and RS) and III(mainly RS), respectively.Group I showed that water quality is good and high diversity of diatom, while Group II and III was waterquality is relatively poor, but not differed in biomass of diatom from Group I. In addition, Group II that had highconductivity, nitrogen and phosphorus, was the lowest in diatom diversity among them. Dominant specieswere Nitzschia palea(17%) and Navicula seminuloides(11%) in Group I, Nitzschia inconspicua(19%) andNavicula perminuta(9%) in Group II, and Nitzschia inconspicua(15%) and Nitzschia palea(14%) in GroupIII, respectively. These taxa were widely distributed in brackish water, and not closely related with specificwater quality, like eutrophic water. However, the groups II and III belonged to RS, had not only little biomass,but bad water quality such as high concentrations of nutrient and chlorophyll-a. Therefore, to determine theeffect of dam construction on the lower water ecosystem, the planktonic algae, which can occur algal bloom inthe estuary, also was considered to be a parallel investigation.

In this paper, we propose encryption method to using complemented MLCA(Maximum Length Cellular Automata) based on NBCA(Null Boundary CA) and 2D CAT (Two-Dimensional Cellular Automata Transform) for efficient image encryption. The encryption method is processed in the following order. First, a transition matrix T is created using the Wolfram Rule matrix. Then, the transition matrix T is multiplied to the original image that is intended to be encrypted, which transfers the pixel values of the original image. Furthermore, the converted original image goes through a XOR operation with complemented vector F to convert into a complemented MLCA applied image. Then, the gateway value is set and 2D CAT basis function is created. Also, the 2D CAT is encrypted by multiplying the created basis function to the complemented MLCA applied image. Lastly, the stability analysis verifies that proposed method holds a high encryption quality status.

To improve the water quality of Shingal Reservoir, a eutrophic lake in South Korea, field tests were performed to assess the influence of water temperature on water quality improvement (WQI) ability of domestic plant-mineral composites (PMCs). Interestingly, Cyanobacterium was found to be dominant even in low-temperature seasons, especially winter leading to more effective for diatom growth. Factors such as phytoplankton, biological oxygen demand (BOD) and phosphorous showed high WQI over 70% at 20 degrees C, but declined to 40% at temperatures above 25 degrees C. WQI for Cyanobacteria decreased with increasing water temperature, whereas for diatoms WQI was 90% regardless of water temperature. Additionally, bacterial density and total nitrogen showed very low WQI without water temperature. Collectively, the results indicate that high water temperature decreased WQI ability of a PMC to control phytoplankton (Microcystis aeruginosa) and increased their ability to control diatoms.

Coblation devices are now widely used in arthroscopic surgery and they show a very low incidence of intraoperative complications. We experienced a case where the tip of the wand separated and migrated into the posterior knee compartment in an arthrofibrotic knee. The free wand tip was identified and then extricated from the popliteal hiatus of the knee with using C-arm fluoroscopic control. To the best of our knowledge, this is the first report of its kind involving coblation wands. We describe this complication to show that the use of coblation devices can lead to unexpected problems and it is imperative to inspect all instruments before and after each surgical use.

We performed laser photocoagulation for extrafoveal feeder vessels in a series of 10 eyes with subfoveal choroidal neovascular membranes (CNVMs) in which feeder vessels could be detected by means of indocyanine green angiography using scanning laser ophthalmoscope. On the follow up indocyanine green angiograms performed within one week after treatment, successful occlusion of the feeder vessels with nonperfusion of the corresponding CNVMs was observed in 8 eyes (80%). Four eyes showed improved visual acuities with resolution of the exudative manifestation. But within 3 months, recanalization of the feeder vessels or further proliferation of the CNVMs developed in 7 eyes. We confirmed the possibility of infarction and regression of the CNVM by feeder vessel photocoagulation, which could improve the visual acuity. But it was rarely possible to maintain them.