Reliable Ultra Trace Analysis of Cd, U and Zn Concentrations in Greenland Snow and Ice by Using Ultraclean Methods for Contamination Control.

This study presents ultraclean procedures used in the challenging task of determining trace elements at or below the pg/g concentration level encountered in Greenland snow and ice. In order to validate these ultraclean procedures, recent snowfall and Holocene ice from northwest Greenland were analyzed for Cd, U, and Zn concentrations. The total procedural blanks brought through the entire measurement procedure proved to be negligible, compared to trace element concentrations, measured in snow and ice samples. This validates the overall practicality of the proposed ultraclean procedures, thereby ensuring the reliable measurements of ultra-trace analysis. A comparison between our study and published data shows that improper procedures employed throughout all stages, from field sampling to analysis to elevate the concentrations by several orders of magnitude, relative to the reliable concentration ranges. The risk of contamination exposure for selected trace elements appears to increase in the order of U < As ≤ Pb < Cd < Zn. Reliable measurements of Cd, U, and Zn concentrations in snow and ice allowed us to interpret the data in terms of seasonal variations in the inputs of crustal and anthropogenic sources to Greenland ice sheet.

A Reliable TTP-Based Infrastructure with Low Sensor Resource Consumption for the Smart Home Multi-Platform.

With the ICT technology making great progress in the smart home environment, the ubiquitous environment is rapidly emerging all over the world, but problems are also increasing proportionally to the rapid growth of the smart home market such as multiplatform heterogeneity and new security threats. In addition, the smart home sensors have so low computing resources that they cannot process complicated computation tasks, which is required to create a proper security environment. A service provider also faces overhead in processing data from a rapidly increasing number of sensors. This paper aimed to propose a scheme to build infrastructure in which communication entities can securely authenticate and design security channel with physically unclonable PUFs and the TTP that smart home communication entities can rely on. In addition, we analyze and evaluate the proposed scheme for security and performance and prove that it can build secure channels with low resources. Finally, we expect that the proposed scheme can be helpful for secure communication with low resources in future smart home multiplatforms.

Occurrence of Legacy and New Persistent Organic Pollutants in Avian Tissues from King George Island, Antarctica.

Legacy and new persistent organic pollutants (POPs), including polychlorinated naphthalenes (PCNs), Dechlorane Plus (DPs) and related compounds (Dechloranes), hexabromocyclododecanes (HBCDs), polychlorinated biphenyls (PCBs), and organochlorine pesticides (OCPs), were analyzed in avian tissue samples from King George Island, Antarctica. The avian species consisted of the Gentoo penguin (Pygoscelis papua), the Adelie penguin (Pygoscelis adeliae), the South polar skua (Stercorarius maccormicki), and the Brown skua (Stercorarius antarcticus). HBCDs were detected in all samples and ranged from 1.67-713 pg/g-lipid. In the penguin samples, the concentrations of PCNs ranged from 0.69-2.07 ng/g-lipid, whereas those in the skua samples ranged from 7.41-175 ng/g-lipid. The levels of Dechloranes ranged from 0.60-1.30 ng/g-lipid in the penguin samples and from 6.57-47.4 ng/g-lipid in the skua samples. The concentrations and congener distributions of OCPs and PCBs were similar to the results of previous reports. The three new POPs were detected in all samples, and this study was one of the first reports on the occurrence of these pollutants in the Antarctic biota. Because Antarctica is one of the most pristine places on Earth, the detection of new POPs in the Antarctic birds, especially penguins, is direct evidence of the long-range transport of pollutants. Furthermore, the concentration ratios of the penguin to the skua samples (BMFs-p) were greater than 1 in most legacy and new POPs, and the BMFs-p values of the new POPs were comparable to those of some OCPs, suggesting a possibility of biomagnification. Despite the small sample size, the results of this study identified POP contamination of the Antarctic avian species and long-range transport and biomagnification of HBCDs, Dechloranes, and PCNs.

Catalyst and doping methods for arc graphene.

Nitrogen-doped graphene synthesis with ∼g scale has been accomplished using the arc discharge method. The defects formed in the synthesis process were reduced by adding various metal catalysts, among which Bi2O3 was found to be the most effective. Adding dopants to the starting materials increased the electrical conductivity of the graphene product, and the doping concentration in graphene was tuned by adjusting the amount of nitrogen dopants. A step-wise technique to fabricate graphene thin films was developed, including dispersion, separation, and filtering processes. The arc graphene can also find its potential application in supercapacitors, taking advantage of its large surface area and improved conductivity by doping.

A Lightweight authentication scheme for IoT against Rogue Base Station Attacks.

Internet of Things (IoT) devices supporting intelligent cloud applications such as healthcare for hospitals rely on connecting with local base stations and access points to provide rich data analysis and real-time services to users. Devices authenticate with local base stations and perform handover operations to connect with access points with higher signal strength. Attackers disguise as valid base stations and access points using publicly accessible SSID information connect with local IoT devices during the handover process and give rise to data integrity and privacy concerns. This paper proposes a lightweight authentication scheme for private blockchain-based networks for securing devices from rogue base stations during the handover process. An authentication certificate is designed for base stations and machines in local clusters using SHA256 and modulo operations for enabling quick handover operations. The keys assigned to each device and base station joining the network are hashed, and their sizes are reduced using modulo operations. Furthermore, the compressed key size forms a certificate, which is used by the machines and the base stations to authenticate mutually. In comparison with existing studies, the performance analysis of the proposed scheme is based on the transmission of three messages required for completing the authentication process. Evaluation based on the Communication Overhead demonstrates a minimum improvement of 99.30% fewer bytes exchanged during the handover process and 89.58% reduced Storage Overhead compared with existing studies.

Record of North American boreal forest fires in northwest Greenland snow.

We present boreal forest fire proxies in a northwest Greenland snowpit spanning a period of six years, from spring 2003 to summer 2009. Levoglucosan (C6H10O5) is a specific organic molecular marker of biomass burning caused by boreal forest fires. In this study, levoglucosan was determined via liquid chromatography/negative ion electrospray ionization-tandem mass spectrometry, wherein isotope-dilution and multiple reaction monitoring methods are employed. Ammonium (NH4+) and oxalate (C2O42-), traditional biomass burning proxies, were determined using two-channel ion chromatography. In the northwest Greenland snowpit, peaks in levoglucosan, ammonium, and oxalate were observed in snow layers corresponding to the summer-fall seasons of 2004 and 2005. Considered together, these spikes are a marker for large boreal forest fires. The levoglucosan deposited in the Greenland snow was strongly dependent on long-range atmospheric transportation. A 10-day backward air mass trajectory analysis supports that the major contributors were air masses from North America. In addition, satellite-derived carbon monoxide (CO) and ammonia (NH3) concentrations suggest that chemicals from North American boreal forest fires during the summer-fall of 2004 and 2005 were transported to Greenland. However, large boreal fires in Siberia in 2003 and 2008 were not recorded in the snowpit. The sub-annual resolution measurements of levoglucosan and ammonium can distinguish between the contributions of past boreal forest fires and soil emissions from anthropogenic activity to Greenland snow and ice.

Occurrence, distribution, and bioaccumulation of new and legacy persistent organic pollutants in an ecosystem on King George Island, maritime Antarctica.

The occurrence and bioaccumulation of new and legacy persistent organic pollutants (POPs), organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), polychlorinated naphthalenes (PCNs), hexabromocyclododecanes (HBCDs), and Dechlorane Plus (DPs) and their related compounds (Dechloranes) in an ecosystem on King George Island, Antarctica are investigated. The new and legacy POPs were widely detected in the animal samples collected from Antarctica, which included Limpet, Antarctic cod, Amphipods, Antarctic icefish, Gentoo and Chinstrap penguins, Kelp gull, and South polar skua. The trophic magnification factors indicated that the levels of PCNs and HBCDs, as well as the legacy POPs, were magnified through the food web, whereas DPs might be diluted through the trophic levels contradicting the classification of Dechloranes as POPs. This is one of the first extensive surveys on PCNs, HBCDs, and Dechloranes, which provides unique information on the distribution and trophic biomagnification potential of the new and legacy POPs in the Antarctic region.

Low-dose persistent organic pollutants increased telomere length in peripheral leukocytes of healthy Koreans.

Although shortened telomeres have been found in many cancers, elongated telomere length has been observed as an early response after low-dose treatment with various chemical carcinogens in vitro and animal experiments, suggesting low-dose exposure to carcinogenic chemicals may function as a tumour promoter at the very early stage of carcinogenesis in humans. This cross-sectional study was performed to examine whether low-dose exposure to persistent organic pollutants (POPs), lipophilic xenobiotics that mainly bioaccumulate in adipose tissue, is associated with telomere length of peripheral blood leukocytes in apparently healthy persons. Telomere length was measured using quantitative polymerase chain reaction method in 84 apparently healthy Koreans. Among various POPs, serum concentrations of organochlorine (OC) pesticides, polychlorinated biphenyls (PCBs) and polybrominated diphenylethers were measured. Most OC pesticides and PCBs were positively and significantly associated with telomere length with correlation coefficients from about +0.25 to +0.35. The strongest associations were observed with p,p'-dichlorodiphenyldichloroethylene, PCB99, PCB153, PCB180, PCB183 and PCB187. When we examined adjusted means of telomere length by quintiles of POPs, the steeper increases of telomere length tended to be observed within relatively lower ranges of POPs. Besides serum concentrations of POPs, none of the other variables studied, including age, were associated with telomere length in this study. We found that telomere length was increasing across low doses of exposure to POPs in which the majority of study subjects were found, suggesting that low-dose POPs may act as a tumour promoter in carcinogenesis in humans.

Role of EUS and MDCT in the diagnosis of gastric submucosal tumors according to the revised pathologic concept of gastrointestinal stromal tumors.

Gastric submucosal tumors (SMTs) consist of various lesions arising from the deep layers of the stomach. Gastrointestinal stromal tumors (GISTs) are undoubtedly the commonest malignant SMTs of the stomach, and therefore the attitude towards the general diagnostic approach for GISTs defines the extended diagnostic plan for SMTs. Two recent consensus meetings were assembled concerning the classification and therapeutic plans for GISTs. These meetings shed light upon the need for the modification of the current role of imaging modalities, including endoscopic ultrasound (EUS) and computed tomography (CT). According to the revised concepts of GISTs, the most important and plausible current role of imaging for the diagnostic approach of gastric SMTs is to differentiate GISTs from other gastric SMTs. This review discusses the newly established diagnostic role of radiology according to the revised classification of GISTs and provides the differential diagnoses based on EUS and CT findings.

Graphite epoxide.

Oxidation of graphite may be carried out by reaction with meta-chloroperoxybenzoic acid to yield graphite epoxide. Scanning tunneling microscopy (STM) showed that the functionalization occurs at the edges rather than on the basal plane of the graphite. Quantification of the epoxide content is possible through the deepoxidation reaction using MeReO3/PPh3.

Suppressing effect of goethite on PCDD/F and HCB emissions from plastic materials incineration.

Polyethylene (PE) and polyvinyl chloride (PVC) are the leading plastics in total production in the world. The incineration of plastic-based materials forms many chlorinated compounds, such as polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs). In this study the addition of goethite (alpha-FeOOH) was investigated to determine its suppressing effect on the emission of PCDD/Fs and hexachlorobenzene (HCB) during the combustion of wastes containing PE and PVC. Goethite was being considered since it acts as a dioxin-suppressing catalyst during incineration. Results showed that incorporation of goethite greatly reduced the generation of PCDD/Fs and HCB in the exhaust gas and fly ash. The concentration of PCDD/Fs in flue gas decreased by 45% for lab-scale and 52% for small incinerator combustion experiments, where the goethite ratios in feed samples were 0.54% and 0.34%, respectively. Under the same conditions, the concentration of HCB in flue gas decreased by 88% and 62%, respectively. The present study showed a possible mechanism of the suppressing effect of the goethite for PCDD/F formation. It is likely that iron chlorides react with particulate carbon to form organo-chlorine compounds and promote PCDD/F formation in the gas phase. XRD analysis of combustion ash revealed that the goethite was partially dehydrated and converted to alpha-Fe(2)O(3) and Fe(3)O(4) but no iron chlorides formation. Therefore the goethite impregnated plastics can contribute the reduction of PCDD/Fs and HCB in the exhaust gas during incineration of MSW.

Levels of polybrominated diphenyl ethers in the Korean metropolitan population are declining: A trend from 2001 to 2013.

Polybrominated diphenyl ethers (PBDEs) have been banned or voluntarily withdrawn from commerce worldwide. Declining levels of PBDEs in humans have been reported elsewhere, but not in Korea. We monitored 7 individual PBDE congeners (BDE-28, BDE-47, BDE-99, BDE-100, BDE-153, BDE-154, and BDE-183) in 103 human serum samples collected in 2006. The arithmetic mean and median values for the sum of the 7 PBDEs (∑PBDEs) were 7.13 and 6.70 ng/g lipid, respectively. In addition, 6 pooled human serum samples collected in 2006, 2007, 2009, 2011, 2012, and 2013 were analyzed. A decrease in PBDE levels was observed, as reflected by the median value of ∑PBDEs from 5.98 in 2006 to 2.98 ng/g lipid in 2013 as well as in the pooled samples. The levels of individual congeners also decreased but at different declining rates. Based on these results and previously reported data, a definite decline in PBDE levels in the Korean metropolitan population could be observed from 2001 to 2013, providing the first evidence in Korea of the same decline observed elsewhere in the world. Environ Toxicol Chem 2018;37:2323-2330. © 2018 SETAC.

Determinants of serum organochlorine pesticide and polychlorinated biphenyl levels in middle-aged Korean adults.

The serum levels of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were measured in a middle-aged Korean population and investigated associations with age, gender, body mass index (BMI), metabolic syndrome (MS), type 2 diabetes mellitus (T2DM), and dietary habits. The median concentrations of 22 OCPs and 34 PCBs in the serum samples were 483 and 216 ng g-1 lipid, respectively. The most abundant compound was p,p'-DDE, followed by PCB 153, ß-HCH, PCB 118, and PCB 180. The results of multiple linear regression and other statistical analyses revealed that serum OCP and PCB levels were higher in women and were positively correlated with age. BMI was positively associated with serum OCP and PCB levels, reflecting the influence of food intake and the preserving effect of body fat. MS and T2DM were significantly associated with serum OCP and PCB levels. The intake of animal foods had positive associations with serum OCP and PCB levels, whereas the intake of phytogenic foods showed negative associations, presumably because of contamination levels in food items and food matrices that governs absorption and excretion of OCPs and PCBs in the body. The relationship between dietary habits and serum OCP and PCB levels were different in participants with MS compared to healthy participants, suggesting MS may alter the influence of food intake on serum OCP and PCB levels.

Congener-specific approach to human PCB concentrations by serum analysis.

The objective of this study was to evaluate all congeners of polychlorinated biphenyls (PCBs) in human serum samples. Concentrations of all PCB congeners in the serum of 87 volunteers were determined by high-resolution gas chromatography/high-resolution mass spectrometry (HRGC/HRMS). The participants consisted of 47 males and 40 females, including 25 men working at municipal solid waste incinerators (MSWIs). The mean concentrations of total PCBs and dioxin-like PCBs were 242.77ng/g lipid (median: 180.17ng/g lipid) and 18.57ng/g lipid (median: 15.34ng/g lipid), respectively. Penta-, hexa-, and heptachlorinated biphenyls contributed more than 80% of the total PCBs detected in human serum. Congener-specific analysis indicated that PCB153, PCB138, PCB180, PCB187, and PCB118 contributed 57.3% of the total PCBs detected in human serum samples. A statistical analysis was performed to determine whether there were significant correlations between PCB concentrations and specific variables such as age, gender, smoking habits, occupation, and body mass index (BMI). However, serum PCB concentrations correlated only with age. In addition, we found that total PCBs and dioxin-like PCBs highly correlated with PCB153 (correlation coefficient r=0.93, p<0.01) and PCB118 (correlation coefficient r=0.98, p<0.01), respectively. Thus these two congeners could be satisfactory indicators for total PCBs and dioxin-like PCBs in human serum.

Pb concentrations and isotopic record preserved in northwest Greenland snow.

We present high-resolution lead (Pb) concentrations and isotopic ratios from a northwest Greenland snow pit covering a six-year period between 2003 and 2009. Pb concentrations ranged widely from 2.7 pg g-1 to 97.3 pg g-1, with a mean concentration of 21.6 pg g-1. These values are higher than those recorded for the pre-industrial period. Pb concentrations exhibit seasonal spikes in winter-spring layers. Crustal Pb enrichment factors (EF) suggest that the northwest Greenland snow pit is highly enriched with Pb of predominantly anthropogenic origin. The 206Pb/207Pb ratios ranged from 1.144 to 1.169 with a mean value of 1.156, which fall between less radiogenic Eurasian-type and more radiogenic Canadian-type signatures. This result suggests that several potential source areas of Pb impact on northwest Greenland. Abrupt changes in Pb concentrations and Pb isotope ratios were observed and related to seasonal shifts in source regions of aerosol transport. The 206Pb/207Pb isotope ratio increased gradually between 2003 and 2009. The similarity of the three-isotope plot (206Pb/207Pb versus 208Pb/207Pb) between some of our samples and Chinese urban aerosols suggests a steadily increasing contribution of Chinese Pb to northwest Greenland snow.

Chest wall metastasis from unknown primary site of hepatocellular carcinoma.

Previous reports of a solitary metastatic hepatocellular carcinoma have been rare. Because this tumor has a different treatment modality and prognosis, an accurate differential diagnosis is essential. Here we report a rare case of a solitary chest wall metastasis from unknown primary site of hepatocellular carcinoma. It involves a 51-year-old man who was admitted to our hospital because of a palpable left upper chest wall mass. The mass was resected and pathologic examination confirmed a diagnosis of metastatic hepatocellular carcinoma. Despite our investigation, no evidence was found that indicated the primary origin of the hepatocellular carcinoma. Four months later, the patient was admitted again because of spinal cord compression at the third and fourth thoracic vertebrae. Emergent decompressive laminectomy was performed and microscopic features revealed the same pathology as the initial chest wall mass resected 4 months earlier. After one year, a follow-up abdominal computed tomography (CT) still revealed no evidence of primary hepatocellular carcinoma.

Determination of lead isotopes in a new Greenland deep ice core at the sub-picogram per gram level by thermal ionization mass spectrometry using an improved decontamination method.

An improved decontamination method and ultraclean analytical procedures have been developed to minimize Pb contamination of processed glacial ice cores and to achieve reliable determination of Pb isotopes in North Greenland Eemian Ice Drilling (NEEM) deep ice core sections with concentrations at the sub-picogram per gram level. A PL-7 (Fuso Chemical) silica-gel activator has replaced the previously used colloidal silica activator produced by Merck and has been shown to provide sufficiently enhanced ion beam intensity for Pb isotope analysis for a few tens of picograms of Pb. Considering the quantities of Pb contained in the NEEM Greenland ice core and a sample weight of 10 g used for the analysis, the blank contribution from the sample treatment was observed to be negligible. The decontamination and analysis of the artificial ice cores and selected NEEM Greenland ice core sections confirmed the cleanliness and effectiveness of the overall analytical process.

Dose-related effect of extracorporeal shock wave therapy for plantar fasciitis.

OBJECTIVE: To examine the dose-related effect of extracorporeal shock wave therapy (ESWT) for plantar fasciitis. METHODS: Sixty patients with plantar fasciitis despite conservative treatment were enrolled. The patients were divided into a low-energy group (group L: n=30, 1,000 shocks/session, energy flux density [EFD] per shock 0.08 mJ/mm(2)) and a medium-energy group (group M: n=30, 1,000 shocks/session, EFD 0.16 mJ/mm(2)). The main outcome measures were visual analogue scale (VAS), Roles and Maudsley (RM) score, and thickness of plantar fascia (PF). To compare the effects between each group, follow-up was carried out 1 week after 3 and 6 sessions, and 1 and 3 months after ESWT. RESULTS: Significant VAS and RM score improvement, and PF thickness reduction were observed in both groups (p<0.01). After 3 sessions of ESWT, group M showed significant improvement in the VAS and RM score than group L, whereas after 3 additional sessions applied in group L, the main outcomes were no longer significantly different in both groups (p>0.05). CONCLUSION: Therapeutic effect might disclose a dose-related relationship; therefore, EFD and the times of the session are considerable factors when treating with ESWT.

Assessment of polybrominated diphenyl ethers (PBDEs) in serum from the Korean general population.

In 2009 and 2010, 720 serum samples were collected from non-occupationally exposed study participants at four Korean locations and monitored for the presence of 27 polybrominated diphenyl ether (PBDE) congeners. The median concentrations of Σ(27)PBDEs (the sum of 27 congeners) and Σ(3-7)PBDEs (the sum of tri- to hepta-BDE congeners) were 6.04 and 4.97 ng/g lipid, respectively. The most abundant congener detected in serum samples was BDE-153, followed by BDE-47 and BDE-99. The median value of Σ(3-7)PBDEs was similar to the median values observed in Asia and Europe, but much lower than that observed in North America. Some significant differences, based on geographic region and sex, were observed. We also observed a positive increase of BDE-153 with regard to age. In addition, we estimated the daily exposure to PBDEs from previously published reports of PBDE concentrations in food and dust, and determined the individual contributions of a variety of sources.

The effect of the forward head posture on postural balance in long time computer based worker.

OBJECTIVE: To estimate the effects of a relatively protruded head and neck posture on postural balance, in computer based worker. METHOD: Thirty participants, who work with computers for over 6 hrs per day (Group I), and thirty participants, who rarely work with computers (Group II), were enrolled. The head and neck posture was measured by estimating angles A and B. A being the angle between the tragus of the ear, the lateral canthus of the eye, and horizontal line and B the angle between the C7 spinous process, the tragus of the ear, and the horizontal line. The severity of head protrusion with neck extension was assessed by the subtraction of angle A from angle B. We also measured the center of gravity (COG) and postural balance by using computerized dynamic posturography to determine the effect of computer-based work on postural balance. RESULTS: Results indicated that group I had a relatively more protruded head with extensive neck posture (angle B-A of group I and group II, 28.2±8.3, 32.9±6.0; p<.05). The COG of group I tended more toward the anterior than that of group II. Postural imbalance and impaired ability to regulate movement in forward and backward direction were also found. CONCLUSION: The results of this study suggest that forward head postures during computer-based work may contribute to some disturbance in the balance of healthy adults. These results could be applied to education programs regarding correct postures when working at a computer for extended periods of time.