Proper Management of Amalgam Powder Embedded in the Alveolus.

The presence of foreign bodies in the mandible is not listed as a risk factor or absolute contraindication for implant rehabilitation. However, possible complications caused by foreign bodies, such as infection and cyst formation, could lead to implant failure. The authors report a case of dental implant placed 4 months after the surgical removal of embedded amalgam in the mandibular alveolus using a trephine bur and bone grafting with mineralized freeze-dried bone allograft. Clinical and radiographic evaluations were performed at each appointment to assess factors such as pain, implant mobility, probing depth, and marginal bone loss around the implant. Within 3 years of implant placement, there were no clinical signs and symptoms and no obvious radiographic marginal bone loss. Dental implant installation appears to be safe following the elimination of foreign materials, so long as anatomic and biological factors and appropriate implant choice, are taken into consideration.

Computational Screening of a Single-Atom Catalyst Supported by Monolayer Nb2S2C for Oxygen Reduction Reaction.

The search for high-performance catalysts to improve the catalytic activity for an oxygen reduction reaction (ORR) is crucial for developing a proton exchange membrane fuel cell. Using the first-principles method, we have performed computational screening on a series of transition metal (TM) atoms embedded in monolayer Nb2S2C to enhance the ORR activity. Through the scaling relationship and volcano plot, our results reveal that the introduction of a single Ni or Rh atom through substitutional doping into monolayer Nb2S2C yields promising ORR catalysts with low overpotentials of 0.52 and 0.42 V, respectively. These doped atoms remain intact on the monolayer Nb2S2C even at elevated temperatures. Importantly, the catalytic activity of the Nb2S2C doped with a TM atom can be effectively correlated with an intrinsic descriptor, which can be computed based on the number of d orbital electrons and the electronegativity of TM and O atoms.

The effect of vacancy defects on the electromechanical properties of monolayer NiTe2 from first principles calculations.

The electromechanical properties of monolayer 1-T NiTe2 under charge actuation were investigated using first-principles density functional theory (DFT) calculations. Monolayer 1-T NiTe2 in its pristine form has a work area density per cycle of up to 5.38 MJ m-3 nm upon charge injection and it can generate a strain and a stress of 1.51% and 0.96 N m-1, respectively. We found that defects in the form of vacancies can be exploited to modulate the electromechanical properties of this material. The presence of Ni-vacancies can further enhance the generated stress by 22.5%. On the other hand, with Te-vacancies, it is possible to improve the work area density per cycle by at least 145% and also to enhance the induced strain from 1.51% to 2.92%. The effect of charge polarity on the contraction and expansion of monolayer 1T-NiTe2 was investigated. Due to its excellent environmental stability and good electromechanical properties, monolayer NiTe2 is considered to be a promising electrode material for electroactive polymer (EAP) based actuators.

Serum vitamin D level correlates with disease activity and health-related quality of life in antineutrophil cytoplasmic antibody-associated vasculitis.

BACKGROUND AND OBJECTIVE: The association between vitamin D levels and disease activity has been established in patients with several autoimmune rheumatic diseases. We aimed to examine the association between vitamin D and disease activity of antineutrophil cytoplasmic antibody-associated vasculitis (AAV). METHODS: Fifty-four AAV patients and 50 age- and sex-matched healthy controls without vitamin D supplements were included. Clinical and laboratory data were evaluated during the assessment of vitamin D levels. Two different forms of vitamin D in the sera-25(OH)D, which is the sum of 25(OH)D2 and 25(OH)D3, and 25(OH)D3, which only includes 25(OH)D in its D3 form-were measured, and the relationship between vitamin D and the obtained data was assessed. Variations in vitamin D levels relative to the season were also evaluated. RESULTS: Patients with AAV demonstrated considerably lower 25(OH)D serum levels than healthy controls (16.0 vs. 20.4 ng/mL, p = 0.016), and the proportion of individuals with vitamin D deficiency was higher in patients with AAV than in healthy controls (68.5% vs. 48.0%, p = 0.035). Both serum 25(OH)D and 25(OH)D3 were positively associated with the 36-item Short-form Health Survey (SF-36) physical component summary and SF-36 mental component summary (MCS) scores. A negative correlation was observed between 25(OH)D and 25(OH)D3 serum levels and Birmingham vasculitis activity score (BVAS), C­reactive protein (CRP), and white blood cell count. Linear regression analysis indicated haemoglobin and 25(OH)D levels to be independently associated with BVAS and CRP and 25(OH)D levels with SF-36 MCS score. No seasonal variations were observed in vitamin D levels. CONCLUSION: The results from this study suggest that vitamin D levels could provide clinically useful information in AAV.

A first-principles study of two-dimensional NbSe2H/g-ZnO van der Waals heterostructures as a water splitting photocatalyst.

Based on first-principles calculations, we propose a new two-dimensional (2D) van der Waals (vdW) heterostructure that can be used as a photocatalyst for water splitting. The heterostructure consists of vertically stacked 2D NbSe2H and graphene-like ZnO (g-ZnO). Depending on the stacking orders, we identified two configurations that have high binding energies with an energy band gap of >2.6 eV. These 2D systems form a type-II heterostructure which enables the separation of photoexcited electrons and holes. The presence of a strong electrostatic potential difference across the 2D NbSe2H and g-ZnO interface is expected to suppress the electron-hole recombination leading to an enhancement in the efficiency of the photocatalytic activity. Our study also shows that the 2D NbSe2H/g-ZnO vdW heterostructure has good thermodynamic properties for water splitting. Furthermore, the optical absorption of the 2D NbSe2H/g-ZnO vdW heterostructure extends into the visible light region. Our results suggest that the 2D NbSe2H/g-ZnO vdW heterostructure is a promising photocatalytic material for water splitting.

Histopathological predictor of the progression from actinic keratosis to squamous cell carcinoma: quantitative computer-aided image analysis.

BACKGROUND: The current histopathological classifications for actinic keratosis (AK) are subjective, and histopathological factors predicting the progression into invasive squamous cell carcinoma (SCC) remain unclear. OBJECTIVES: To quantitatively assess the histopathological findings of AK and to investigate the predisposing factors for malignant transformation of AK. METHODS: A total of 502 AK specimens were retrospectively reviewed. The AK lesions were divided into the atrophic, intermediate, hypertrophic and bowenoid types. Histopathological features were quantitatively analysed using computer-aided image analysis. RESULTS: The epidermal thickness excluding the horny layer increased with statistical significance (P < 0.001) in order of atrophic, intermediate, hypertrophic and bowenoid type. The proportion of keratinocytic atypia was not significantly different among subtypes, except for the bowenoid type. Five of 498 cases were confirmed to develop into SCC. Bowenoid type, epidermal thickening and higher proportion of keratinocytic atypia were significantly associated with progression to invasive SCC in univariate analysis (OR = 12.571, 95% CI: 1.392-113.57; OR = 1.004, 95% CI: 1.001-1.007; OR = 1.069, 95% CI: 1.011-1.130, respectively). In multivariate analysis, only the proportion of keratinocytic atypia was an independent predisposing factor for progression to invasive SCC (OR = 1.069; 95% CI: 1.011-1.130). CONCLUSIONS: Histopathological subtypes based on the essential change of the epidermis well correlated with the actual epidermal thickness excluding the horny layer. The overall severity of keratinocytic atypia might be an independent risk factor for malignant transformation of AK.

Realization of Harmonic Oscillator Arrays with Graded Semiconductor Quantum Wells.

The harmonic oscillator is a foundational concept in both theoretical and experimental quantum mechanics. Here, we demonstrate harmonic oscillators in a semiconductor platform by faithfully implementing continuously graded alloy semiconductor quantum wells. Unlike current technology, this technique avoids interfaces that can hamper the system and allows for the production of multiwell stacks several micrometers thick. The experimentally measured system oscillations are at 3 THz for two structures containing 18 and 54 parabolic quantum wells. Absorption at room temperature is achieved: this is as expected from a parabolic potential and is unlike square quantum wells that require cryogenic operation. Linewidths below 11% of the central frequency are obtained up to 150 K, with a 5.6% linewidth obtained at 10 K. Furthermore, we show that the system correctly displays an absence of nonlinearity despite electron-electron interactions-analogous to the Kohn theorem. These high-quality structures already open up several new experimental vistas.

The Results of Two-stage Revision for Methicillin-resistant Periprosthetic Joint Infection (PJI) of the Hip.

INTRODUCTION: Periprosthetic joint infection (PJI) of the hip due to methicillin-resistant bacteria is difficult to treat and remain a challenge for arthroplasty surgeon. MATERIAL AND METHODS: Retrospective review was done to the patients who received two-stage revisions with an antibiotic loaded cement-spacer for PJI of the hip between January 2010 to May 2015. We found 65 patients (65 hips) with positive culture findings. Eight patients were lost to follow-up and excluded from the study. Among the rest of the 57 patients, methicillin-resistant infection (MR Group) was found in 28 cases. We also evaluate the 29 other cases that caused by the other pathogen as control group. We compared all of the relevant medical records and the treatment outcomes between the two groups. RESULTS: The mean of follow-up period was 33.7 months in the methicillin-resistant group and 28.4 months in the control group (p = 0.27). The causal pathogens in the methicillin-resistant group were: Methicillin-resistant Staphylococcus aureus (MRSA) in 10 cases, Methicillin-resistant Staphylococcus epidermidis (MRSE) in 16 cases and Methicillin-resistant coagulase-negative Staphylococcus (MRCNS) in two cases. The reimplantation rate was 92.8% and 89.6% in the methicillin-resistant and control group, respectively (p= 0.66). The rates of recurrent infection after reimplantation were 23.1% (6/26) in the methicillin-resistant group and 7.6% (2/26) in the control group (p= 0.12). The overall infection control rate was 71.4% (20/28) and 89.6% (26/29) in the methicillin-resistant and control group, respectively (p = 0.08). Both groups showed comparable baseline data on mean age, BMI, gender distribution, preoperative ESR/CRP/WBC and comorbidities. CONCLUSIONS: Two-stage revision procedure resulted in low infection control rate and high infection recurrency rate for the treatment of methicillin-resistant periprosthetic joint infection (PJI) of the hip. Development of the treatment strategy is needed to improve the outcome of methicillin-resistant periprosthetic joint infection (PJI) of the hip.

Surgical treatment of nasolabial cysts in a single institute.

OBJECTIVES: To analyse the results of treatment for nasolabial cysts according to whether an intraoral sublabial or endoscopic transnasal approach was used, and to determine the recent surgical trend in our hospital. METHODS: Twenty-four patients with a histopathologically and radiologically confirmed nasolabial cyst between January 2010 and December 2017 were enrolled in this study. RESULTS: Nasolabial cysts were predominant in females (91.7 per cent) and on the left side (54.2 per cent). Treatment involved an intraoral sublabial approach in 12 cases (48.0 per cent) and a transnasal endoscopic approach in 13 cases (52.0 per cent). In 13 cases (52.0 per cent) surgery was performed under local anaesthesia, while in 12 cases (48.0 per cent) it was conducted under general anaesthesia. The most common post-operative complications were numbness of the upper lip or teeth (n = 9, 36.0 per cent). Only one patient (4.0 per cent), who underwent a transnasal endoscopic approach, experienced a reoccurrence. CONCLUSION: Surgical resection through an intraoral sublabial or transnasal endoscopic approach is the best treatment for a nasolabial cyst, showing very good results and a low recurrence rate. The recent surgical trend in our hospital is to treat nasolabial cysts using a transnasal endoscopic approach under local anaesthesia.

Outcomes of treatment of mammary analogue secretory carcinoma of the parotid gland.

Mammary analogue secretory carcinoma (MASC) of the salivary gland is a newly-described, rare, malignant tumour. Few patients present with MASC of the parotid gland, so the exact characteristics, outcomes of treatment, and prognosis are unknown. The aim of this study was to analyse the clinical features and outcomes of treatment of MASC of the parotid gland in patients being treated at a single hospital. Five patients with histopathologically-confirmed MASC of the parotid gland between January 2015 and August 2018 were retrospectively enrolled. In all cases preoperative fine-needle aspiration cytology had failed to provide an accurate diagnosis. All patients underwent a macroscopically complete oncological resection. Two patients had postoperative radiotherapy (RT). On immunohistochemical examination all tumours stained for S-100 and mammaglobin but not for DOG1. There were no regional recurrences or distant metastases in any of the patients at their last follow-up. We obtained good results for patients with MASC of the parotid gland with surgical treatment and postoperative RT.

Dental implant and fungus ball in the ethmoid sinus.

Dental migration into the ethmoid sinus is extremely rare. Furthermore, it is very unusual that a displaced dental implant is associated with a concomitant fungus ball in the ethmoid sinus. Herein, we report an unusual case of the coexistence of a dental implant and fungus ball in the ethmoid sinus. It appears that this condition has not been reported previously.

Prognosis of patients with gastric variceal bleeding after endoscopic variceal obturation according to the type of varices.

BACKGROUND AND AIMS: This study was performed to evaluate the treatment efficacy of endoscopic variceal obturation (EVO) in patients with gastric variceal bleeding (GVB) according to the type of varices. PATIENTS AND METHODS: All patients who were treated with EVO for bleeding from gastric varices (GVs) were included. Patients with a previous history of endoscopic treatment for GVB and those with accompanying portal vein invasion by hepatocellular carcinoma or other malignancy were excluded. RESULTS: Ninety-one patients with GVB were included. Mean age was 59.4±12.4 years and 72 (79.1%) patients were men. The types of varices were gastroesophageal varices (GOV) type 1 (GOV1), GOV2, and isolated gastric varices type 1 (IGV1) in 30 (33.3%), 35 (38.5%), and 26 (28.6%) patients, respectively. Hemostasis and GV obliteration were achieved in 88 (96.7%) and 81 (89.0%) patients, respectively. Among 81 patients with GV obliteration, GV recurred in 26 (32.1%) patients. The GV recurrence rate was significantly lower in patients with GOV1 than in those with GOV2 (P=0.007), while it was comparable between patients with GOV1 and IGV1 (P=0.111) and between patients with GOV2 and IGV1 (P=0.278). Variceal rebleeding occurred in 11 (13.6%) patients. GVB recurrence rate was significantly higher in patients with GOV2 than in those with GOV1 (P=0.034) and IGV1 (P=0.018), while it was comparable between patients with GOV1 and IGV1 (P=0.623). Mortality rate was comparable among the three groups. CONCLUSIONS: EVO was very effective in patients with GVB. GV recurrence and GV rebleeding were significantly lower in patients with GOV1 than in those with GOV2.

Minimally Invasive Total Hip Arthroplasty in a Patient with Hereditary Multiple Exostoses: A Case Report.

Hip geometry abnormalities found in patients with hereditary multiple exostoses (HME) could promote premature hip joint degeneration which needs treatment. We report the case of a 45-year old male with right hip arthrosis who underwent two-incision minimally invasive (MIS-2) total hip arthroplasty (THA), with satisfactory outcome. This technique could be an alternative approach for performing THA in patients with hereditary multiple exostoses.

Atomic clock performance enabling geodesy below the centimetre level.

The passage of time is tracked by counting oscillations of a frequency reference, such as Earth's revolutions or swings of a pendulum. By referencing atomic transitions, frequency (and thus time) can be measured more precisely than any other physical quantity, with the current generation of optical atomic clocks reporting fractional performance below the 10-17 level1-5. However, the theory of relativity prescribes that the passage of time is not absolute, but is affected by an observer's reference frame. Consequently, clock measurements exhibit sensitivity to relative velocity, acceleration and gravity potential. Here we demonstrate local optical clock measurements that surpass the current ability to account for the gravitational distortion of space-time across the surface of Earth. In two independent ytterbium optical lattice clocks, we demonstrate unprecedented values of three fundamental benchmarks of clock performance. In units of the clock frequency, we report systematic uncertainty of 1.4 × 10-18, measurement instability of 3.2 × 10-19 and reproducibility characterized by ten blinded frequency comparisons, yielding a frequency difference of [-7 ± (5)stat ± (8)sys] × 10-19, where 'stat' and 'sys' indicate statistical and systematic uncertainty, respectively. Although sensitivity to differences in gravity potential could degrade the performance of the clocks as terrestrial standards of time, this same sensitivity can be used as a very sensitive probe of geopotential5-9. Near the surface of Earth, clock comparisons at the 1 × 10-18 level provide a resolution of one centimetre along the direction of gravity, so the performance of these clocks should enable geodesy beyond the state-of-the-art level. These optical clocks could further be used to explore geophysical phenomena10, detect gravitational waves11, test general relativity12 and search for dark matter13-17.

Multivariate statistical analysis for selecting optimal descriptors in the toxicity modeling of nanomaterials.

The present study is based on the application of a multivariate statistical analysis approach for the selection of optimal descriptors of nanomaterials with the objective of robust qualitative modeling of their toxicity. A novel data mining protocol has been developed for the selection of an optimal subset of descriptors of nanomaterials by using the well-known multivariate method principal component analysis (PCA). The selected subsets of descriptors were validated for qualitative modeling of the toxicity of nanomaterials in the PC space. The analysis and validation of the proposed schemes were based on five decisive nanomaterial toxicity data sets available in the published literature. Optimal descriptors were selected on the basis of the maximum loading criteria and using a threshold value of cumulative variance ≤90% on PC directions. A maximum inter-class separation(B) and the minimum intra-classes separation(A) were obtained for toxic vs. nontoxic nanomaterials in the PC space with the selected subsets of optimal descriptors compared to their other combinations for each of the datasets.

Synchronous pleomorphic adenoma and oncocytic carcinoma in the ipsilateral parotid gland.

Synchronous benign and malignant tumours in the ipsilateral parotid gland are rare. We present a case of pleomorphic adenoma and oncocytic carcinoma in the same parotid gland. Clinicians should be aware of the possibility of such synchronous multiple tumours, and that careful dissection and palpation during operation are important to diagnose them.

Faraday-Shielded dc Stark-Shift-Free Optical Lattice Clock.

We demonstrate the absence of a dc Stark shift in an ytterbium optical lattice clock. Stray electric fields are suppressed through the introduction of an in-vacuum Faraday shield. Still, the effectiveness of the shielding must be experimentally assessed. Such diagnostics are accomplished by applying high voltage to six electrodes, which are grounded in normal operation to form part of the Faraday shield. Our measurements place a constraint on the dc Stark shift at the 10^{-20} level, in units of the clock frequency. Moreover, we discuss a potential source of error in strategies to precisely measure or cancel nonzero dc Stark shifts, attributed to field gradients coupled with the finite spatial extent of the lattice-trapped atoms. With this consideration, we find that Faraday shielding, complemented with experimental validation, provides both a practically appealing and effective solution to the problem of dc Stark shifts in optical lattice clocks.

Association between ambient air pollution and pregnancy rate in women who underwent IVF.

STUDY QUESTION: Are the concentrations of five criteria air pollutants associated with probabilities of biochemical pregnancy loss and intrauterine pregnancy in women? SUMMARY ANSWER: Increased concentrations of ambient particulate matter (PM10), nitrogen dioxide (NO2), carbon monoxide (CO) during controlled ovarian stimulation (COS) and after embryo transfer were associated with a decreased probability of intrauterine pregnancy. WHAT IS KNOWN ALREADY: Exposure to high ambient air pollution was suggested to be associated with low fertility and high early pregnancy loss in women. STUDY DESIGN, SIZE, DURATION: Using a retrospective cohort study design, we analysed 6621 cycles of 4581 patients who underwent one or more fresh IVF cycles at a fertility centre from January 2006 to December 2014, and lived in Seoul at the time of IVF treatment. PARTICIPANTS/MATERIALS, SETTING, METHODS: To estimate patients' individual exposure to air pollution, we computed averages of hourly concentrations of five air pollutants including PM10, NO2, CO, sulphur dioxide (SO2) and ozone (O3) measured at 40 regulatory monitoring sites in Seoul for each of the four exposure periods: period 1 (start of COS to oocyte retrieval), period 2 (oocyte retrieval to embryo transfer), period 3 (embryo transfer to hCG test), and period 4 (start of COS to hCG test). Hazard ratios (HRs) from the time-varying Cox-proportional hazards model were used to estimate probabilities of biochemical pregnancy loss and intrauterine pregnancy for an interquartile range (IQR) increase in each air pollutant concentration during each period, after adjusting for individual characteristics. We tested the robustness of the result using generalised linear mixed model, accounting for within-woman correlation. MAIN RESULTS AND THE ROLE OF CHANCE: Mean age of the women was 35 years. Average BMI was 20.9 kg/m2 and the study population underwent 1.4 IVF cycles on average. Cumulative pregnancy rate in multiple IVF cycles was 51.3% per person. Survival analysis showed that air pollution during periods 1 and 3 was generally associated with IVF outcomes. Increased NO2 (adjusted HR = 0.93, 95% CI: 0.87, 0.99) and CO (0.94, 95% CI: 0.89, 1.00) during period 1 were associated with decreased probability of intrauterine pregnancy. PM10 (0.92, 95% CI: 0.85, 0.99), NO2 (0.93, 95% CI = 0.86, 1.00) and CO (0.93, 95% CI: 0.87, 1.00) levels during period 3 were also inversely associated with intrauterine pregnancy. Both PM10 (1.17, 95% CI: 1.04 1.33) and NO2 (1.18, 95% CI: 1.03, 1.34) during period 3 showed positive associations with biochemical pregnancy loss. LIMITATIONS, REASONS FOR CAUTION: The district-specific ambient air pollution treated as an individual exposure may not represent the actual level of each woman's exposure to air pollution. Smoking, working status, parity or gravidity of women, and semen analysis data were not included in the analysis. WIDER IMPLICATIONS OF THE FINDINGS: This study provided evidence of an association between increased ambient concentrations of PM10, NO2 and CO and reduced probabilities for achieving intrauterine pregnancy using multiple IVF cycle data. Specifically, our results indicated that lower intrauterine pregnancy rates in IVF cycles may be linked to ambient air pollution during COS and the post-transfer period. STUDY FUNDING/COMPETING INTEREST(S): This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2013 R1A6A3A04059017, 2016 R1D1A1B03933410 and 2018 R1A2B6004608) and the National Cancer Center of Korea (NCC-1810220-01). The authors report no conflicts of interest. TRIAL REGISTRATION NUMBER: N/A.

Template-free synthesis of monolithic carbon xerogels with hierarchical porosity from resorcinol and formaldehyde via hydrothermal reaction.

Monolithic carbon xerogels with hierarchical porosity were prepared from resorcinol (R) and formaldehyde (F) via a base-catalysed hydrothermal polycondensation reaction, without a template and supercritical drying. First, an aqueous solution of resorcinol, formaldehyde and sodium carbonate was prepared by varying R/W (25-45) and R/C (1-10k) ratios to produce monolithic RF gels. The reaction was carried out in a pressurized Teflon mould at 100 °C for 6 h to give a co-continuous pore structure via spinodal decomposition and a tenacious gel to avoid supercritical drying. Next, the RF gels were dried for 42 h at 60 °C and another 6 h at 100 °C to produce RF xerogels without cracks, followed by pyrolysis in a tube furnace at 900 °C for 2 h under N2 flow, and then activation at 1000 °C for 2, 4 or 6 h under CO2 flow. Finally, the carbon xerogels were characterized by SEM and N2 adsorption-desorption measurements. Monolithic RF gels were obtained from all combinations of R/W and R/C, but the gels from R/W = 45 exhibited a co-continuous large-pore structure, providing a specific surface area (SSA) of ∼650 m2 g-1, which increased to 3311 m2 g-1 (for R/C = 10k) at 6 h of CO2 activation without exhibiting cracks. N2 isotherms demonstrated that micro- and meso-pores were introduced via activation, forming hierarchical porosity in combination with large pores from spinodal decomposition without using a template.