Thermal neutron transmutation doping of GaN semiconductors

High quality Ge doping of GaN is demonstrated using primarily thermal neutrons for the first time. In this study, GaN was doped with Ge to concentrations from 10¹⁶ Ge atoms/cm³ to 10¹⁸ Ge atoms/cm³. The doping concentrations were measured using gamma-ray spectroscopy and confirmed using SIMS analysis. The data from SIMS analysis also show consistent Ge doping concentration throughout the depth of the GaN wafers. After irradiation, the GaN was annealed in a nitrogen environment at 950 °C for 30 min. The neutron doping process turns out to produce spatially uniform doping throughout the whole volume of the GaN substrate.

Universal scaling of adsorption of nonionic surfactants on carbonates using cloud point temperatures

HYPOTHESIS

Nonionic surfactants alter the wettability of oil-wet carbonate surfaces to a water-wet state. The degree of surfactant adsorption is expected to determine the extent of the wettability alteration. Furthermore, the structure of the hydrophobic and hydrophilic units of the surfactant should affect the degree of adsorption and correlate with the wettability alteration.

EXPERIMENTS

The adsorption on Indiana limestone was measured for nonionic surfactants with two different types of hydrophobic units and hydrophilic polyethoxylate units ranging from 15 to 40 mers. Measurements were conducted for several surfactant concentrations and temperatures.

FINDINGS

Adsorption increased with temperature and for surfactants with fewer hydrophilic groups. The adsorption occurs as micelles rather than individual surfactant molecules. An increase in adsorption is observed for the more hydrophobic surfactants at higher temperature and is attributed to the increase in micelle sizes. Adsorption collapses onto a universal curve as a function of the difference between cloud point of the surfactant and system temperature. At the same time wettability alteration was found to have a direct correlation with surfactant adsorption. These findings are critical for judicious selection of nonionic surfactants for analysis and design of wettability alteration for oil reservoirs.

Molecular Dynamics Simulations of Aqueous Nonionic Surfactants on a Carbonate Surface

The interactions and structure of secondary alcohol ethoxylates with 15 and 40 ethoxylate units in water near a calcite surface are studied. It is found that water binds preferentially to the calcite surface. Prediction of the free-energy landscape for surfactant molecules shows that single-surfactant molecules do not adsorb because they cannot get close enough to the surface because of the water layer for attractive ethoxylate-calcite or dispersion interactions to be significant. Micelles can adsorb onto the surface even with the intervening water layer because of the integrative effect of the attractive interactions of all the surfactant molecules. Adsorption is found to increase because of the closer proximity of the micelles to the surface due to a weakened water layer at higher temperatures. The free-energy well and barrier values are used to estimate surface to bulk partition coefficients for different surfactants and temperatures, and qualitative agreement is found with experimental observations. The combined effect of surfactant-water and surfactant-solid interactions is found to be responsible for an increased adsorption for nonionic surfactants as the system approaches the cloud point.

Review of Free Prostate-Specific Antigen Assay Utilization at Danbury Hospital

Introduction

Measuring the concentration of free fraction of prostate-specific antigen (fPSA) present in serum in addition to the total PSA (tPSA) concentration has been shown to enhance specificity over tPSA alone in evaluating male patients with mild-moderate elevations of tPSA in the diagnostic “gray zone” (4.0-10.0 ng/mL) and negative findings on digital rectal exam. The clinical utility of fPSA has not been demonstrated outside the tPSA gray zone, as the probability of prostate cancer is very low at tPSA <4.0 and very high at tPSA >10.0. However, many clinicians order tPSA and fPSA concurrently without first knowing the results of the tPSA. This study was to review orders for fPSA and provide suggestions for improving utilization.

Methods

Paired test results for concurrently ordered tPSA and fPSA tests during the time periods of January to February 2018 and January to February 2019 (before and after laboratory information system upgrade) were extracted for quality assurance purposes. No patient identifiers were included. Data were sorted and the percentage of “appropriate” fPSA orders was calculated for each time period.

Results

The number of concurrent total and fPSA tests ordered was 174 for January-February 2018 and 232 for January-February 2019. The number of tPSA within the 4.0 to 10.0 ng/mL range was 78 for January-February 2018 and 148 for January-February 2019. The percentage of “appropriate” fPSA test orders (tPSA 4.0-10.0 ng/mL) was 44.8% for January-February 2018 and 63.8% for January-February 2019.

Conclusion

A high percentage of inappropriate fPSA orders was found during both time periods. Inappropriate fPSA testing is not only unnecessary and wasteful but can lead to diagnostic errors. Options for driving improved utilization include automatic canceling of fPSA orders when tPSA is not within the diagnostic gray zone and offering fPSA as a “reflex” test that is performed only when tPSA is within the diagnostic gray zone.

Reconstruction and evaluation of changes in hydrologic conditions over a transboundary region by a regional climate model coupled with a physically-based hydrology model: Application to Thao river watershed

The differences among countries in terms of physical features, governmental policies, priorities in short- and long-term water resources management may lead to conflicts in managing and sharing of water resources over the transboundary regions. Due to no formal data sharing agreement between countries, there has been usually no data availability at transboundary regions. In this study, a methodology, in which a physically-based hydrology model was coupled with a regional climate model, is proposed to reconstruct and evaluate hydrologic conditions over transboundary regions. For the case study, Thao river watershed (TRW), within Vietnam and China, was selected. The Watershed Environmental Hydrology (WEHY) model was implemented based on topography, soil, and land use/cover information which was retrieved from global satellite data resources. The watershed model-WEHY was first validated over the TRW, and then was used to reconstruct historical hydrologic conditions during 1950-2007. The results of this study suggest no significant trend in the annual streamflow over the target watershed. In addition, there is a time shift in the wet season between the upstream sector in China and the downstream sector in Vietnam over the TRW. The annual flow contribution from the upstream sector in China to the outlet of TRW is estimated to be around 66%, and the remaining 34% contribution comes from the downstream sector in Vietnam territory. Last but not the least, the annual flow as a function of return period varies not only with the return period but also as a function of the time window, reflecting the effect of the changing regime on the streamflows at the TRW. The evolution of the flow frequency through time is an evidence of the ongoing non-stationarity in the hydrologic conditions over TRW.

Candidaemia and a risk predictive model for overall mortality: a prospective multicentre study

Background

Candidaemia is associated with high mortality. Variables associated with mortality have been published previously, but not developed into a risk predictive model for mortality. We sought to describe the current epidemiology of candidaemia in Australia, analyse predictors of 30-day all-cause mortality, and develop and validate a mortality risk predictive model.

Methods

Adults with candidaemia were studied prospectively over 12 months at eight institutions. Clinical and laboratory variables at time of blood culture-positivity were subject to multivariate analysis for association with 30-day all-cause mortality. A predictive score for mortality was examined by area under receiver operator characteristic curves and a historical data set was used for validation.

Results

The median age of 133 patients with candidaemia was 62 years; 76 (57%) were male and 57 (43%) were female. Co-morbidities included underlying haematologic malignancy (n = 20; 15%), and solid organ malignancy in (n = 25; 19%); 55 (41%) were in an intensive care unit (ICU). Non-albicans Candida spp. accounted for 61% of cases (81/133). All-cause 30-day mortality was 31%. A gastrointestinal or unknown source was associated with higher overall mortality than an intravascular or urologic source (p < 0.01). A risk predictive score based on age > 65 years, ICU admission, chronic organ dysfunction, preceding surgery within 30 days, haematological malignancy, source of candidaemia and antibiotic therapy for ≥10 days stratified patients into < 20% or ≥ 20% predicted mortality. The model retained accuracy when validated against a historical dataset (n = 741).

Conclusions

Mortality in patients with candidaemia remains high. A simple mortality risk predictive score stratifying patients with candidaemia into < 20% and ≥ 20% 30-day mortality is presented. This model uses information available at time of candidaemia diagnosis is easy to incorporate into decision support systems. Further validation of this model is warranted.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-4065-5) contains supplementary material, which is available to authorized users.

MON-388 To Cut Or Not To Cut? Cystic Adrenal Lymphangioma Mimicking Pheochromocytoma

Background:Lymphangiomas are rare benign vascular tumors. Adrenal gland lymphangiomas are an even less common occurrence. Although usually non-functional, these tumors may mimic pheochromocytomas [1]. We present a case of a patient with a cystic adrenal lymphangioma with elevated catecholamines in the setting of acute appendicitis. Case presentation:A 30 year-old-man with a history of intermittent anxiety presented with abdominal pain. An abdominal computer tomography (CT) scan, physical examination, and laboratory findings were consistent with acute appendicitis. The patient was incidentally found to have a well-demarcated 3.9x4.6 cm right adrenal mass measuring 10 HU. A prior CT scan of the abdomen performed four years earlier showed a 2.5x3.2 cm right adrenal mass. Hormonal evaluation had not been conducted at that time.Further evaluation during the hospitalization revealed normal electrolytes, dehydroepiandrosterone, overnight dexamethasone suppression test, aldosterone/renin ratio and plasma catecholamines. However, 24-hour urine catecholamines and metanephrines were elevated: epinephrine - 63 mcg/24hr (n<21), norepinephrine - 106 mcg/24hr (n 15-80) and dopamine - 540 mcg/24hr (n 65-400). Due to the size of the lesion (>4 cm), surgical resection was recommended. Due to concern that abnormal urinary values could indicate pheochromocytoma, the surgery was preceded by 14 days of alpha-adrenergic blockade. The patient underwent a successful laparoscopic right adrenalectomy with concomitant interval appendectomy. Final pathology results revealed a cystic lymphangioma of the right adrenal gland with positive D2-40 and CD-31 immunohistochemical stains supporting this diagnosis. During follow-up evaluation, the patient reported interval resolution of intermittent anxiety and urine catecholamines/metanephrines gradually normalized. While not confirmatory of a catecholamine secreting adrenal lymphangioma, interval resolution of the anxiety disorder could suggest this diagnosis as a possibility to consider. Conclusion:The rare nature of adrenal lymphangiomas has led to a paucity of information regarding their detection and management [2]. Although typically considered benign, there are no methods at our disposal to confirm this diagnosis without surgical removal. Adrenal lymphangiomas mimicking other adrenal masses, including pheochromocytoma, have been reported [2]. Increasing the awareness regarding these rare tumors may enable providers to be on the lookout for adrenal lymphangiomas when evaluating patients for large unilateral adrenal lesions. References:1. Hodish I, Schmidt L, Moraitis AG. Adrenal Lymphangioma Masquerading as a Catecholamine Producing Tumor. Case Rep Endocrinol. 2015;2015:380151.2. Michalopoulos N, Laskou S, Karayannopoulou G, et al. Adrenal Gland Lymphangiomas. Indian J Surg. 2015; 77:S1334-S1342.

Reduced sensitivity of multiparametric MRI for clinically significant prostate cancer in men under the age of 50

Introduction

Three percent of all new diagnosed prostate cancer (PC) patients are under the age of 50. Multiparametric MRI (mpMRI) is considered as increasingly powerful tool for decision-making in diagnosis of PC and in some active surveillance protocols. Since prostate architecture changes with age, we evaluated the sensitivity of mpMRI to detect clinically significant PC in patients under the age of 50 compared to pair-matched older patients.

Methods

Data from a prospective collected and ethics approved database were retrospectively analyzed. We reviewed 1,395 records of PC patients from the years 2012–2017, identifying those under the age of 50 who had radical prostatectomy as primary treatment, a pre-operative mpMRI, a full clinical data set and who had clinically significant cancer (N=51). Tumor size and International Society of Urological Pathology (ISUP) score pair-matching was performed for patients older than 55 years. Clinically significant cancer was defined as ISUP >2 or ISUP 2 with >5% Gleason 4. The sensitivity to detect clinically significant cancer with mpMRI was calculated using pre-operative Prostate Imaging Reporting and Data System (PI-RADS) score and whole-gland final pathology.

Results

The median patient age in the young and older groups was 47 and 62, respectively. Both cohorts matched significantly regarding tumor volume (P =0.91) and ISUP score (P =1.0). The median PI-RADS score for the young group was 3, and 4 for the older group. The sensitivity for mpMRI, for PI-RADS 3,4 and 5 was 80.3% (95% CI 66.8%–90.1%) in the young group and 84.3% in the older group (95% CI 71.4%–92.9%), demonstrating no statistically significant difference (P=0.603). Sensitivity of mpMRI for PI-RADS 4,5 was 49.0% (95% CI 34.7%–63.4%) for the young group and 72.5% (95% CI 58.2%–84.1%) for the older group, which differ significantly (P=0.014).

Conclusions

mpMRI may have a reduced sensitivity for detecting clinically significant PC in patients under the age of 50 for PI-RADS score 4,5 lesions. Many significant PC lesions were reported as PI-RADS 3 under the age of 50. We recommend that increased significance is placed on PI-RADS 3 lesions found in patients under the age of 50.

Wettability Alteration of Calcite by Nonionic Surfactants

The process of selecting an effective surfactant for wettability alteration is dependent on a number of factors, including mineral type, temperature, salinity, and nature of adsorbed oil and ultimately how the molecular structure of the surfactant interacts with all of these. Here, we present an experimental study of the effectiveness of nonionic surfactants with different hydrophobic groups and different lengths of hydrophilic ethylene oxide oligomers. The surfactants selected alter the wettability of the rock primarily by acting on the water-rock and oil-rock interfaces. The dynamics of wettability alteration is measured by the evolution of contact angles of oil drops on initially oil-wet surfaces at three different temperatures. Wettability alteration is found to be enhanced by surfactants with shorter hydrophilic units and increased temperatures. Experimental observations are efficiently summarized by a few thermodynamic and kinetic parameters. Qualitative experiments are performed to study surfactant-induced dewetting of oil films. Finally, a model involving "coating" and "sweeping" mechanisms is proposed to explain the mechanism of surfactant action.

Association of the Platelet Glycoprotein IIIa PIA1/A2 Gene Polymorphism to Coronary Artery Disease but not to Nonfatal Myocardial Infarction in Low Risk Patients

Background. The platelet membrane glycoprotein IIb/IIIa functions as a receptor for fibrinogen and von Willebrand factor during platelet aggregation. In a small case-control study, evidence has been presented that the PlA2 allele of the platelet glycoprotein GPIIIa PlA1/A2 gene polymorphism might be an independent risk factor for acute myocardial infarction (MI). Methods and Results. We explored the association of the PlA1A2 to the severity of coronary artery disease (CAD), as assessed angiographically in 2252 male individuals, and to myocardial infarction (MI). The severity of coronary heart disease (CHD) was also estimated by calculating a CHD score according to Gensini. The PlA genotype was determined by allele specific restriction digestion. Relation of the PlA2 allele to CAD: In the total population, the frequency of the PlA2 allele was not associated to the presence or to the extent of CAD. Also the CHD scores of PlA1/PlA2 genotypes were essentially the same. However, after exclusion of individuals with high BMI (≥26.9 kg/m2) and/or low apoAI (<1.43 g/l) PlA2PlA2 carriers had clearly higher CHD scores than PlA1PlA1 genotypes; PlA1PlA2 heterozygotes had intermediate values (p <0.05). After division of the study population into one group of individuals without any angiographic signs of CAD (CHD score = 0) and into another group of patients with severe CAD (CHD score (≥120), a strong association of the PlA2 allele with severe CAD was also found in the same low risk groups; e.g. exclusion of persons with high BMI and low apoAI resulted in an Odds ratio of 5.37 (1.46-19.7) (p <0.02). Relation of the PlA2 allele to MI: No association was found between PlA1/PlA2 genotypes and risk of MI neither in the total population nor in low risk subgroups.

Conclusions. Whereas no difference in the distribution of allele and genotype frequencies between controls and survivors of MI could be detected, the PlA2 allele is associated with CHD in low risk patients.

Patterns of failure on Ga PSMA (GaPSMA) and F18 FDG (FDG) PET CT in a prospective phase 2 trial of 177Lu DKFZ PSMA 617 (LuPSMA) in men with castrate resistant metastatic prostate cancer (mCRPC)

2562

Background: LuPSMA is emerging as an effective therapy in mCRPC, with retrospective series reporting high PSA response rates in men undergoing treatment (tx). However, not all men have prolonged tx responses. We report the prospective imaging (GaPSMA/FDG) and PSA response of men who progress biochemically during LuPSMA tx to gain information on characteristics of failure patterns, to determine optimal future tx strategies. Methods: Men with mCRPC, who had failed androgen blockade, failed/ ineligible/refused chemotherapy, with GaPSMA positive disease were enrolled in a prospective phase 2 trial. All men underwent LuPSMA therapy 6-8Gbq, 4 doses at 6 weekly intervals. Imaging with FDG, GaPSMA, bone scan and CT scans was at screening, at subsequent PSA rise, or 3 months post completion of 4 cycles of therapy. Results: 14 men met eligibility criteria and enrolled. 4/14 (28%) men had progressive disease (no PSA response). 10/14 (72%) PSA reduced by a mean 56% .Overall 9/14 (64%) men had >30% decline in PSA, and 5/15(36%) >50% reduction in PSA. 7/15 men were reimaged with GaPSMA, FDG at biochemical failure or 3/12 post tx completion. Imaging revealed 4 distinct patterns (P) of progression. Conclusions: PSMA acts as both target for radionuclide therapy and biomarker for effective tx response. PSMA and FDG imaging at PSA failure following or during LU PSMA therapy identifies phenotypic patterns of failure that have implications for determining next best tx options in men with mCRPC. [Table: see text]

Select men benefit from androgen deprivation therapy delivered with salvage radiation therapy after prostatectomy

BACKGROUND

Which men benefit most from adding androgen deprivation therapy (ADT) to salvage radiation therapy (SRT) after prostatectomy has not clearly been defined; therefore, we evaluated the impact of ADT to SRT on failure-free survival (FFS) in men with a rising or persistent PSA after prostatectomy.

METHODS

We identified 332 men who received SRT after prostatectomy from 1987 to 2010. Recursive partitioning analysis (RPA) identified favorable, intermediate and unfavorable groups based on the risk of failure after SRT alone. Kaplan-Meier and log-rank tests compared FFS with and without ADT.

RESULTS

Forty-three percent received SRT alone and 57% received SRT with ADT (median 6.6 months (interquartile range (IQR) 5.8-18.1) ADT). Median SRT dose was 70 Gy (IQR 70-70), and median follow-up after SRT was 6.7 years (IQR 4.5-10.8). On Cox's proportional hazard regression, ADT improved FFS (adjusted hazard ratio 0.60, 95% confidence interval: 0.42-0.86; P=0.006). RPA classified unfavorable disease as negative surgical margins (SMs) and preradiation PSA of ⩾0.5 ng ml^-1. Favorable disease had neither adverse factor, and intermediate disease had one adverse factor. The addition of ADT to SRT improved 5-year FFS for men with unfavorable disease (70.3% vs 23.4%; P<0.001) and intermediate disease (69.8% vs 48.0%; P=0.003), but not for men with favorable disease (81.2% vs 78.0%; P=0.971).

CONCLUSIONS

The addition of ADT to SRT appears to improve FFS for men with a preradiation PSA of ⩾0.5 ng ml^-1 or with negative SM at prostatectomy. Men with involved surgical margins and PSA <0.5 ng ml^-1 appear to be at a lower risk of failure after SRT alone and may not derive as much benefit from the administration of ADT with SRT. These results are hypothesis-generating only, and further prospective data are required to see if ADT can safely be omitted in this select group of men.