bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural insights on the pamoic acid and the 8 kDa domain of DNA polymerase beta complex: Towards the design of higher-affinity inhibitors
Authors: Hazan Corinne , Boudsocq François , Gervais Virginie , Saurel Olivier , Ciais Marion , Cazaux Christophe , Czaplicki Jerzy , Milon Alain
Published: April 2008

Background

DNA polymerase beta (pol beta), the error-prone DNA polymerase of single-stranded DNA break repair as well as base excision repair pathways, is overexpressed in several tumors and takes part in chemotherapeutic agent resistance, like that of cisplatin, through translesion synthesis. For this reason pol beta has become a therapeutic target. Several inhibitors have been identified, but none of them presents a sufficient affinity and specificity to become a drug. The fragment-based inhibitor design allows an important improvement in affinity of small molecules. The initial and critical step for setting up the fragment-based strategy consists in the identification and structural characterization of the first fragment bound to the target.

Results

We have performed docking studies of pamoic acid, a 9 micromolar pol beta inhibitor, and found that it binds in a single pocket at the surface of the 8 kDa domain of pol beta. However, docking studies provided five possible conformations for pamoic acid in this site. NMR experiments were performed on the complex to select a single conformation among the five retained. Chemical Shift Mapping data confirmed pamoic acid binding site found by docking while NOESY and saturation transfer experiments provided distances between pairs of protons from the pamoic acid and those of the 8 kDa domain that allowed the identification of the correct conformation.

Conclusion

Combining NMR experiments on the complex with docking results allowed us to build a three-dimensional structural model. This model serves as the starting point for further structural studies aimed at improving the affinity of pamoic acid for binding to DNA polymerase beta.
Implementation and evaluation of the SPRINT protocol for tight glycaemic control in critically ill patients: a clinical practice change
Authors: Chase JGeoffrey , Shaw Geoffrey , Le Compte Aaron , Lonergan Timothy , Willacy Michael , Wong Xing-Wei , Lin Jessica , Lotz Thomas , Lee Dominic , Hann Christopher
Published: April 2008

Introduction

Stress-induced hyperglycaemia is prevalent in critical care. Control of blood glucose levels to within a 4.4 to 6.1 mmol/L range or below 7.75 mmol/L can reduce mortality and improve clinical outcomes. The Specialised Relative Insulin Nutrition Tables (SPRINT) protocol is a simple wheel-based system that modulates insulin and nutritional inputs for tight glycaemic control.

Methods

SPRINT was implemented as a clinical practice change in a general intensive care unit (ICU). The objective of this study was to measure the effect of the SPRINT protocol on glycaemic control and mortality compared with previous ICU control methods. Glycaemic control and mortality outcomes for 371 SPRINT patients with a median Acute Physiology And Chronic Health Evaluation (APACHE) II score of 18 (interquartile range [IQR] 15 to 24) are compared with a 413-patient retrospective cohort with a median APACHE II score of 18 (IQR 15 to 23).

Results

Overall, 53.9% of all measurements were in the 4.4 to 6.1 mmol/L band. Blood glucose concentrations were found to be log-normal and thus log-normal statistics are used throughout to describe the data. The average log-normal glycaemia was 6.0 mmol/L (standard deviation 1.5 mmol/L). Only 9.0% of all measurements were below 4.4 mmol/L, with 3.8% below 4 mmol/L and 0.1% of measurements below 2.2 mmol/L. On SPRINT, 80% more measurements were in the 4.4 to 6.1 mmol/L band and standard deviation of blood glucose was 38% lower compared with the retrospective control. The range and peak of blood glucose were not correlated with mortality for SPRINT patients (P >0.30). For ICU length of stay (LoS) of greater than or equal to 3 days, hospital mortality was reduced from 34.1% to 25.4% (-26%) (P = 0.05). For ICU LoS of greater than or equal to 4 days, hospital mortality was reduced from 34.3% to 23.5% (-32%) (P = 0.02). For ICU LoS of greater than or equal to 5 days, hospital mortality was reduced from 31.9% to 20.6% (-35%) (P = 0.02). ICU mortality was also reduced but the P value was less than 0.13 for ICU LoS of greater than or equal to 4 and 5 days.

Conclusion

SPRINT achieved a high level of glycaemic control on a severely ill critical cohort population. Reductions in mortality were observed compared with a retrospective hyperglycaemic cohort. Range and peak blood glucose metrics were no longer correlated with mortality outcome under SPRINT.
Covering random points in a unit disk
Authors: Hansen Jennie C. , Schmutz Eric , Sheng Li
Published: April 2008

Let D be the punctured unit disk. It is easy to see that no pair x, y in D can cover D in the sense that D cannot be contained in the union of the unit disks centred at x and y. With this fact in mind, let Vn = {X1, X2, …, Xn}, where X1, X2, … are random points sampled independently from a uniform distribution on D. We prove that, with asymptotic probability 1, there exist two points in Vn that cover all of Vn.
Decay property of stopped Markovian bulk-arriving queues
Authors: Li Junping , Chen Anyue
Published: April 2008

We consider decay properties including the decay parameter, invariant measures, invariant vectors, and quasistationary distributions of a Markovian bulk-arriving queue that stops immediately after hitting the zero state. Investigating such behavior is crucial in realizing the busy period and some other related properties of Markovian bulk-arriving queues. The exact value of the decay parameter λC is obtained and expressed explicitly. The invariant measures, invariant vectors, and quasistationary distributions are then presented. We show that there exists a family of invariant measures indexed by λ ∈ [0, λC]. We then show that, under some conditions, there exists a family of quasistationary distributions, also indexed by λ ∈ [0, λC]. The generating functions of these invariant measures and quasistationary distributions are presented. We further show that a stopped Markovian bulk-arriving queue is always λC-transient and some deep properties are revealed. The clear geometric interpretation of the decay parameter is explained. A few examples are then provided to illustrate the results obtained in this paper.
Nonexplosion of a class of semilinear equations via branching particle representations
Authors: Chakraborty Santanu , López-Mimbela Jose Alfredo
Published: April 2008

We consider a branching particle system where an individual particle gives birth to a random number of offspring at the place where it dies. The probability distribution of the number of offspring is given by pk, k = 2, 3, …. The corresponding branching process is related to the semilinear partial differential equation for x ∈ ℝd, where A is the infinitesimal generator of a multiplicative semigroup and the pks, k = 2, 3, …, are nonnegative functions such that We obtain sufficient conditions for the existence of global positive solutions to semilinear equations of this form. Our results extend previous work by Nagasawa and Sirao (1969) and others.
Law of Large Numbers for Dynamic Bargaining Markets
Authors: Ferland René , Giroux Gaston
Published: April 2008

We describe the random meeting motion of a finite number of investors in markets with friction as a Markov pure-jump process with interactions. Using a sequence of these, we prove a functional law of large numbers relating the large motions with the finite market of the so-called continuum of agents.
Ordering of Optimal Portfolio Allocations in a Model with a Mixture of Fundamental Risks
Authors: Cheung Ka Chun , Yang Hailiang
Published: April 2008

In this paper we study a single-period optimal portfolio problem in which the aim of the investor is to maximize the expected utility. We assume that the return of every security in the market is a mixture of some common underlying source of risks. A sufficient condition to order the optimal allocations is obtained, and it is shown that several models studied in the literature before are special cases of the proposed model. In the course of the analysis concepts in stochastic orders are employed, and a new characterization of the likelihood ratio order is obtained.
Transient Moments of the TCP Window Size Process
Authors: Löpker Andreas H. , van Leeuwaarden Johan S. H.
Published: April 2008

The TCP window size process can be modeled as a piecewise-deterministic Markov process that increases linearly and experiences downward jumps at Poisson times. We present a transient analysis of this window size process. Our main result is the Laplace transform of the transient moments. Formulae for the integer and fractional moments are derived, as well as an explicit characterization of the speed of convergence to steady state. Central to our approach are the infinitesimal generator and Dynkin's martingale.
The Limit Behavior of Dual Markov Branching Processes
Authors: Li Yangrong , Pakes Anthony G. , Li Jia , Gu Anhui
Published: April 2008

A dual Markov branching process (DMBP) is by definition a Siegmund's predual of some Markov branching process (MBP). Such a process does exist and is uniquely determined by the so-called dual-branching property. Its q-matrix Q is derived and proved to be regular and monotone. Several equivalent definitions for a DMBP are given. The criteria for transience, positive recurrence, strong ergodicity, and the Feller property are established. The invariant distributions are given by a clear formulation with a geometric limit law.
Reduced Branching Processes with Very Heavy Tails
Authors: Lagerås Andreas N. , Sagitov Serik
Published: April 2008

The reduced Markov branching process is a stochastic model for the genealogy of an unstructured biological population. Its limit behavior in the critical case is well studied for the Zolotarev-Slack regularity parameter α ∈ (0, 1]. We turn to the case of very heavy-tailed reproduction distribution α = 0 assuming that Zubkov's regularity condition holds with parameter β ∈ (0, ∞). Our main result gives a new asymptotic pattern for the reduced branching process conditioned on nonextinction during a long time interval.
Weak Local Linear Discretizations for Stochastic Differential Equations with Jumps
Authors: Carbonell F. , Jimenez J. C.
Published: April 2008

Weak local linear approximations have played a prominent role in the construction of effective inference methods and numerical integrators for stochastic differential equations. In this note two weak local linear approximations for stochastic differential equations with jumps are introduced as a generalization of previous ones. Their respective order of convergence is obtained as well.
Beat the Mean: Sequential Selection by Better Than Average Rules
Authors: Krieger Abba M. , Pollak Moshe , Samuel-Cahn Ester
Published: April 2008

We consider a sequential rule, where an item is chosen into the group, such as a university faculty member, only if his/her score is better than the average score of those already belonging to the group. We study four variables: the average score of the members of the group after k items have been selected, the time it takes (in terms of the number of observed items) to assemble a group of k items, the average score of the group after n items have been observed, and the number of items kept after the first n items have been observed. We develop the relationships between these variables, and obtain their asymptotic behavior as k (respectively, n) tends to ∞. The assumption throughout is that the items are independent and identically distributed with a continuous distribution. Though knowledge of this distribution is not needed to implement the selection rule, the asymptotic behavior does depend on the distribution. We study in some detail the exponential, Pareto, and beta distributions. Generalizations of the ‘better than average’ rule to the β better than average rules are also considered. These are rules where an item is admitted to the group only if its score is better than β times the present average of the group, where β > 0.
On the Truncated Long-Range Percolation on Z2
Authors: de Lima Bernardo Nunes Borges , Sapozhnikov Artëm
Published: April 2008

We consider an independent long-range bond percolation on Z2. Horizontal and vertical bonds of length n are independently open with probability p_n ∈ [0, 1]. Given ∑n=1∞∏i=1n(1 − pi) < ∞, we prove that there exists an infinite cluster of open bonds of length less than or equal to N for some large but finite N. The result gives a partial answer to the truncation problem.
Diagnostic Biopsy of Lymph Nodes of the Neck, Axilla and Groin: Rhyme, Reason or Chance?
Authors: Moor James W , Murray Patrick , Inwood Jane , Gouldesbrough David , Bem Chris
Published: April 2008

INTRODUCTION

Improving patient pathways of care is becoming increasingly important in the delivery of timely, appropriate surgical care. With this aim, we analysed the referral and management pathway of patients undergoing diagnostic superficial lymph node biopsy.

PATIENTS AND METHODS

A retrospective review of case notes of patients undergoing diagnostic superficial lymph node biopsy over 3 years, 1998–2000 at the Bradford Hospitals NHS Trust. Indication for surgical biopsy was based on clinical suspicion following assessment in the out-patient clinic for the majority, and arrangement of investigations as deemed appropriate. There were no clinical algorithms in use during the study period.

RESULTS

There was no evidence for the use of explicit protocols for referral or management. Biopsy was often delayed. Of 268 patients referred from primary care, referral was made to any of 14 hospital departments with 39% (105 of 268) attending more than one outpatient appointment, and 155 (41 of 268) attending more than one department. Eighteen percent (47 of 268) of patients were informed of their diagnosis within 6 weeks of referral and 42% (113 of 268) within 3 months of referral. Nine percent (24 of 268) underwent pre-operative fine needle aspiration cytology. Of patients with enlarged neck nodes, 29% (52/180) had examination of the upper aero-digestive tract.

CONCLUSIONS

The study supports the introduction of co-ordinated problem-based referral and management pathways for the management of patients with enlarged superficial lymph nodes supported by regular audits of practice.
Challenges to Evidence-Based Prescribing in Clinical Practice
Authors: Mamdani Muhammad , Ching Andrew , Golden Brian , Melo Magda , Menzefricke Ulrich
Published: April 2008

Although there appears to be widespread support of evidence-based medicine as a basis for rational prescribing, the challenges to it are signilicant and often justified. A multitude of factors other than evidence drive clinical decision-making, including patient preferences and social circumstances, presence of diseasedrug and drug-drug interactions, clinical experience, competing demands from more pressing clinical conditions, marketing and promotional activity, and systemlevel drug policies.
Intravenous Human Plasma-Derived Augmentation Therapy in α1-Antitrypsin Deficiency: From Pharmacokinetic Analysis to Individualizing Therapy
Authors: Zamora Nuria Padullés , Pla Rafael Vidal , Rio Pilar Gispert Del , Margaleff Rosendo Jardi , Frias Francisco Rodriguez , Ronsano Jose Bruono Montero
Published: April 2008

Background:

Severs forms of α1-antitrypsin (AAT) deficiency require augmentation therapy by intravenous administration of purified preparations of AAT concentrate. Although standard AAT treatment schedules are widely available, pharmacokinetic studies characterizing AAT serum decay are scarce, and data on the variability of individual patients are almost nonexistent.

Objective:

To establish individual AAT pharmacokinetics and develop a predictive model based on simple pharmacokinetic characterization that can be used to optimize Individual AAT dosing regimens.

Methods:

Seven patients with severe hereditary AAT deficiency (PI*ZZ phonotype) with serum AAT levels less than 0.50 g/L Initially received AAT 180 mg/kg every 3 weeks. At 7, 14, and 21 days after AAT administration, serum samples were taken for quantitative AAT analysis and further one-compartment pharmacokinetic analysis. Subsequently, patients were rescheduled (dose and dosing interval) according to their individual responses. The influence of baseline AAT level, age, sex, body weight, and commercial AAT preparation was evaluated.

Results:

The mean ± SD AAT pharmacokinetic profile was: volume of distribution 127.6 ± 31.9 mL/kg, clearance 10.13 ± 1.84 mL/kg/day, and half-life 8.7 ± 1.0 days. Hence, the mean optimized final AAT dose was 123.1 mg/kg every 2 weeks (range 118.5-125.6). AAT concentrations differed by a mean (geometrical) value of 3.9% (range -4.2% to 6.7%) from the minimum desired AAT serum trough of 0.50 g/L. The impact of baseline AAT levels and commercial AAT preparation used was statistically significant (p = 0.033 and p = 0.035, respectively). Differences between estimated and actual values were slightly lower when baseline AAT levels were taken into consideration, with a mean value ot 3.3% (range -4.2% to 6.1%).

Conclusions:

AAT augmentation therapy can be effectively individualized on a pharmacokinetic basis with a simple, easily executed method.
Complexity of Interactions Between Voriconazole and Antiretroviral Agents
Authors: Yakiwchuk Erin M , Foisy Michelle M , Hughes Christine A
Published: April 2008

Objective:

To evaluate and summarize pertinent aspects of the literature on interactions between voriconazole and antiretroviral agents.

Data Sources:

Primary literature was identified through MEDLINE (1950-February 2008), EMBASE (1988-February 2008), and International Pharmaceutical Abstracts (1970-February 2008) using the search terms voriconazole, ritonavir, protease inhibitors, nonnucleoside reverse transcriptase inhibitors, raltegravir, maraviroc, and drug interactions. Additionally, relevant abstracts from infectious diseases and HIV conferences (2004-February 2008), reference citations from relevant publications, and product information monographs were reviewed.

Study Selection And Data Abstraction:

All articles identified from the data sources and published in English were reviewed. Of these, studies and reports addressing voriconazole pharmacokinetics or interactions with antiretroviral agents were evaluated.

Data Synthesis:

The interactions between voriconazole and antiretroviral drugs are complex. Voriconazole and ritonavir exhibit a time- and dose-dependent interaction. Ritonavir initially inhibits voriconazole metabolism, but, with chronic administration, subsequently induces voriconazole metabolism. This interaction is more pronounced with high doses of ritonavir. Coadministration of voriconazole and efavirenz at usual doses is contraindicated because of a 2-way interaction resulting in efavirenz toxicity and decreased therapeutic effect of voriconazole. Dosage adjustments of both drugs are required. Based on pharmacokinetic characteristics, interactions between voriconazole and other protease inhibitors, nonnucleoside reverse transcriptase inhibitors (including etravirine), and maraviroc are likely but have not been well characterized in the literature. Interactions between voriconazole and nucleoside reverse transcriptase inhibitors or raltegravir are not anticipated.

Conclusions:

Interactions between voriconazole and antiretrovirals have the potential for serious consequences. However, because there is limited information available, further studies are warranted to establish these interactions and clarify their appropriate management. Until then, clinicians should be aware of the potential for interactions between voriconazole and antiretroviral agents and how to monitor for these interactions in clinical practice.
Immunologic Benefits of Enfuvirtide in Patients Enrolled in a Drug Assistance Program
Authors: Saberi Parya , Caswell Nikolai H , Gruta Cristina I , Tokumoto Jason N , Dong Betty J
Published: April 2008

Background:

Randomized clinical trials have demonstrated that enfuvirtide plus an optimized background regimen can cause a significant increase in CD4+ cell counts and a reduction in HIV RNA levels.

Objective:

To describe and anaiyze CD4+ cell count and HIV RNA changes in HIV-infected patients receiving enfuvirtide and a prescribed background regimen (PBR) in a primarily clinical setting.

Methods:

A retrospective review from September 1998 through August 2005 of CD4+ cell counts and HIV RNA changes from baseline was conducted in patients receiving enfuvirtide. Data were stratified and analyzed according to baseline CD4+ cell count and HIV RNA.

Results:

A mean CD4+ cell count increase of approximately 102 cells/mm3 was observed, regardless of baseline CD4+ cell count, in 187 patients receiving enfuvirtide during a mean of 19.4 months of follow-up. During 3 years of follow-up, patients initiating enfuvirtide at CD4+ cell counts less than 100 cells/mm3 never achieved absolute CD4+ cell counts comparable to the counts in patients starting enfuvirtide at CD4+ cell counts of 100 cells/mm3 or more. In 38.3% of patients achieving an undetectable HIV RNA level, a mean CD4+ cell count increase of 185 cells/mm3 was observed. An unexpected finding was that a mean CD4+ cell count increase of 76 cells/mm3 occurred in 61.7% of patients not achieving complete viral suppression.

Conclusions:

Immunologic benefits were observed in subjects continuing enfuvirtide plus a PBR irrespective of baseline CD4+ cell count, complete viral suppression, or antiretroviral susceptibility data. Dala suggest that initiation of enfuvirtide at CD4+ cell counts greater than 100 celis/mm3 may be immunologically advantageous and independent of complete virologic response.
Covert Marketing Unmasked: A Legal and Regulatory Guide for Practices that Mask Marketing Messages
Authors: Petty Ross D. , Andrews J. Craig
Published: April 2008

Masked marketing—one form of covert marketing—involves marketing communications that appear to be from independent third parties rather than from product marketers. This article presents a typology of masked marketing practices, illustrating whether they may be deceptive to consumers. To accomplish this, the authors apply the Federal Trade Commission's three-part definition of deception (i.e., misleadingness, reasonable consumer, and materiality) in the evaluation of such practices. The article concludes with policy recommendations including areas for further research.
Status of JAERI Material Performance Database (JMPD) and Its Use for Analyses of Aqueous Environmentally Assisted Cracking Data
Authors: Kaji Y , Tsukada T , Miwa Y , Tsuji H , Nakajima H
Published: April 2008

A material performance database for nuclear applications, which was named the JAERI Material Performance Database (JMPD), has been developed since 1986 with a view to utilizing various kinds of characteristic data of nuclear materials efficiently. The data stored in the JMPD are mainly fatigue crack growth data on low alloy steels, creep data on superalloys, tensile data on aluminum alloys and stress corrosion cracking data (slow strain rate testing (SSRT), crack growth rate, etc.) on austenitic stainless steels.

Irradiation assisted stress corrosion cracking (IASCC) of austenitic stainless steels in high temperature water has been considered as a degradation phenomenon potential not only in the light water reactors (LWRs) but rather common in systems where the materials are exposed simultaneously to radiation and water environments.

This paper describes the present status of the JMPD, which is available through the Internet partially. Furthermore, some trials of utilization of the system focused on the issues relating to IASCC are mentioned as follows: the effect of alloy composition, dissolved oxygen and neutron fluence on IASCC susceptibilities and SCC growth rate could be drawn.
Improvement of IASCC Resistance for Austenitic Stainless Steels in PWR Environment
Authors: Yonezawa T , Fujimoto K , Iwamura T , Nishida S
Published: April 2008

In recent years, irradiation-assisted stress-corrosion cracking (IASCC) of austenitic stainless steels for core internal component materials became a subject of concern for in light water reactors (LWRs). Intergranular cracking of baffle former bolts has been found in pressurized water reactors (PWRs) after long operating periods. Therefore, the authors investigated the possibility of IASCC in austenitic stainless steels used for core internal materials of PWRs in order to estimate the degradation of PWR plants up to the end of their lifetime. In this study, in order to verify the hypothesis that the IASCC in PWRs can be caused by the primary water stress-corrosion cracking (PWSCC) as a result of radiation-induced segregation (RIS) at grain boundaries, the authors melted materials whose bulk compositions simulated the grain boundary compositions of irradiated austenitic stainless steels. The effects of chromium, nickel and silicon content on PWSCC susceptibility was studied by slow strain-rate tensile (SSRT) tests. In order to improve the IASCC resistance of austenitic stainless steels for PWRs, authors developed modified 316CW(cold worked) and high chromium stainless steels. The former steel has high chromium content and ultra low impurity elements within the specification of chemical composition for ASTM A193 B8M Type 316 stainless steel. The latter steel has high chromium content of up to 30% chromium and ultra low impurity elements. Both materials are aged after solution annealing, in order to precipitate the M23C6 carbides coherent with the austenitic matrices along the grain boundaries and to recover the sensitization.
Environmentally Assisted Cracking in the Chemical Process Industry. Stress Corrosion Cracking of Iron, Nickel, and Cobalt Based Alloys in Chloride and Wet HF Services
Authors: Rebak RB
Published: April 2008

Many different alloys are used in the fabrication equipment for the chemical process industry (CPI) and the most common of these alloys are iron base (stainless steels). During service, the primary cause of failure of engineering alloys is stress corrosion cracking (SCC). Although the occurrence of environmentally induced cracking might be prevented by reducing the level of tensile stresses on components, this approach is seldom practiced. In some cases, failure can be avoided through a proper alloy selection based on results from laboratory testing. The aim of this paper is to assess the predictive capabilities of laboratory testing for cases of SCC in the CPI. Instances of chloride cracking and wet hydrofluoric acid (HF) cracking in the field are analyzed based on results from laboratory testing.
Chlorophyll Fluorescence as a Bioindicator of Photosynthesis Inhibition from Solar Ultraviolet Radiation in Plants and Algae
Authors: Marwood CA , Dobson E , Smith REH , Solomon KR , Greenberg BM
Published: April 2008

Chlorophyll fluorescence is a simple, rapid technique for measuring photosynthetic efficiency in plants and algae. Pulse-amplitude modulated chlorophyll fluorescence was examined in aquatic plants and natural assemblages of Lake Erie phytoplankton exposed to solar ultraviolet (UV) radiation. UV-exclusion studies were performed in which plastic films were used to screen sunlight to remove ultraviolet-B radiation (295–320 ran), or UVB plus ultraviolet-A radiation (320–400 nm) in outdoor aquatic microcosms and ship exposure chambers. UV had negligible impacts on photosynthesis and growth in the aquatic macrophyte Myriophyllum spicatum in microcosms. However, photosynthetic electron transport in natural assemblages of Lake Erie phytoplankton was substantially diminished by short exposures to full sunlight. Phytoplankton exposed to full sunlight for 30 min lost 90 % of maximum photosystem II efficiency (Fv/Fm) and 75 % of the effective yield of photosystem II photochemistry (ΔF/Fm). Diminished photosynthetic electron transport was primarily due to UVB wavelengths in sunlight. UVA and visible wavelengths also diminished photosynthetic electron transport to a lesser extent. Thus, this assay represents a general bioindicator of effects from environmental stress in freshwater plants and algae that is able to detect impacts due to current and increasing levels of UVB.
Estero Salado / Guayaquil Ship Channel Contaminant Assessment
Authors: Arhelger ME , Parker FR , Jensen PA , Boyd CE
Published: April 2008

Testing of maintenance material from the Estero Salado and some side bays off the Bay of Guayaquil was conducted, including chemical and bacteriological analyses of sediment and suspended particulate phase (SPP) bioassays, using both the Pacific white shrimp, Penaeus vannamei, in Guayaquil, Ecuador and the “opossum shrimp”, Mysidopsis bahia in Houston, Texas. The SPP was prepared from channel or bay sediments and shrimp farm intake water. The work was designed to determine the potential environmental short-term (acute) impact of the proposed openbay disposal of maintenance material to be dredged from the Estero Salado.

The chemical analyses demonstrated no cause for concern relative to usual estuary sediments but demonstrated metals concentrations well above those normally found in sediments from shrimp ponds near Guayaquil. The bioassays with P. vannamei showed almost no acute toxicity but, did show some sublethal effects, including counts of Vibrio bacteria, a bacteria of concern to shrimp farmers worldwide. The mysid bioassays demonstrated both lethal and sublethal effects from the 100% SPP of several channel stations.

An analysis of the material to be dredged suggests that the plume from the proposed discharge can generate a significant and easily detectable increase over background turbidity near the discharge.The area affected by the increase in suspended sediment could encompass many of the shrimp farm intakes, which could provide an environmental stress to shrimp in the farms. All of this leads to the conclusion that the open bay discharge of material from the Estero Salado may cause problems to the shrimp farms that fringe Guayaquil Bay. Measures to reduce the amount of additional turbidity that would be generated during disposal were suggested.
Terrestrial Toxicity Testing with Volatile Substances
Authors: Stephenson GL , Princz JI , Koper N , Miasek PG
Published: April 2008

The toxicity of volatile hydrocarbons to terrestrial organisms is currently being investigated. It was found that toxicity test methods required procedural modification during test soil preparation to minimize the loss of the test substance due to volatilization. A series of tests was initiated with an artificial and field-collected reference soil to investigate alternative test-soil, preparation, methodologies for evaluating motor gasoline (mogas) as it predominantly contains highly volatile low-end carbon components (⩽C5–C13). The proposed approaches to minimize volatilization losses included the application of mogas at concentrations sufficiently high to accommodate the percentage lost during test soil preparation; the modification of test soil preparation methods; and the modification of the nature of test units. The analyses of benzene, toluene, ethylbenzene, xylene (BTEX) compounds, total purgeable hydrocarbons (TPuH), total extractable hydrocarbons (TEH), and total petroleum hydrocarbons (TPH) from soil samples quantified the losses of these mogas constituents at each stage of preparation. The constituents of the mogas were found to volatilize at different rates and the losses were to some extent, concentration dependent. Amending test soils at higher concentrations than required for an adverse effect compensated for the rate of the losses due to volatilization. Significant amounts of the mogas were lost regardless of the methods used to prepare the test soils. Alternative “closed” (minimized air exchange) test units were considered useful and acceptable, as they optimized exposure of the test organism to mogas and did not compromise their survival. The test methods developed to assess the toxicity of mogas in terrestrial organisms may be equally applicable to the toxicity testing of other highly volatile substances.
Workplace TRIG and Air-Purifying Respiratory Protection
Authors: Poovey HG , Rando RJ
Published: April 2008

Paired total and respirable particulate samples were collected in the breathing zone of 186 painters at five Air Force bases. Using the composition of the starting material to estimate total reactive isocyanate group (TRIG), exposure levels were 0.87 mg/M3 (geometric mean) in the total fraction and 0.12 mg/M3 in the respirable fraction with geometric standard deviations of 2.7 and 3.3, respectively. Dichotomous samplers specific for TRIG were used during the painting of a military vehicle and indicated 0.39 ± 0.15 mg/M3 TRIG. This was 20 times the Health and Safety Executive's recommended time weighted average for TRIG. The TRIG levels seen in these studies indicate the need for personal protective equipment or additional engineering controls. Breakthrough studies with 1,6 hexamethylene diisocyanate (HDI) and HDI-biuret were conducted on a series of negative pressure air purifying respirator (APR) cartridges. Initial penetration of TRIG through the APR cartridges ranged from greater than 70% to less than 3% giving apparent protection factors of >1.5 and >33. These samples also showed that HDI was present in the aerosol fraction at levels significantly below its saturated vapor pressure.
Modeling of Phosphorus Accumulation on Grain Boundaries in Iron Alloys under Irradiation
Authors: Pechenkin VA , Stepanov IA , Konobeev YV
Published: April 2008

Kinetics of phosphorus accumulation on grain boundaries (GB) in iron-based alloys is treated theoretically, taking into account both the radiation-induced segregation (RIS) in the matrix and the Gibbsian adsorption (GA) at GB. For steady-state conditions analytical expressions are derived for component profiles near GB and component concentrations on GB. Modeling of phosphorus accumulation at GB in iron alloys is carried out using two different models: 1) the McLean's model generalized to take into account the radiation-enhanced phosphorus diffusion via vacancy and interstitial mechanisms as well as RIS near GB, 2) a model of RIS in a ternary Fe-P-Ni alloy accounting for the binding energy of phosphorus atoms with interstitials as well as a possibility of high phosphorus content near GB at high irradiation doses. Predictions of modeling are analyzed regarding the dependence on temperature, dose and Fe and P diffusion parameters available for iron alloys. It is shown that the GB phosphorus concentration calculated as a function of temperature reveals one or two maxima depending on dose and the choice of material parameters.
Investigation of Temper Embrittlement in Reactor Pressure Vessel Steels Following Thermal Aging, Irradiation, and Thermal Annealing
Authors: Nanstad RK , McCabe DE , Sokolov MA , English CA , Ortner SR
Published: April 2008

The Heavy-Section Steel Irradiation Program at Oak Ridge National Laboratory includes a task to investigate the propensity for temper embrittlement in coarse grain regions of heat-affected zones in prototypic reactor pressure vessel (RPV) steel weldments as a consequence of irradiation and thermal annealing. For the present studies, five prototypic RPV steels with specifications of A302 grade B, A302 grade B (modified), A533 grade B class 1, and A508 class 2 were given two different austenitization treatments and various thermal aging treatments. Thermal aging treatments were conducted at 399, 425, 454 and 490°C for times of 168 and 2000 h. Charpy V-notch impact toughness vs temperature curves were developed for each condition with ductile-brittle transition temperatures used as the basis for comparing the effects of the various heat treatments. Very high austenitization heat treatment produced extremely large grains which exhibited a very high propensity for temper embrittlement following thermal aging. Intergranular fracture was the predominant mode of failure in many of the materials and Auger analysis confirmed significant segregation of phosphorus at the grain boundaries. Lower temperature austenitization treatment performed in a super Gleeble to simulate prototypic coarse grain microstructures in submerged-arc weldments produced the expected grain size with varying propensity for temper embrittlement dependent on the material as well as on the thermal aging temperature and time. Although the lower temperature treatment resulted in decreased propensity for temper embrittlement, the results did provide motivation for the investigation of the potential for phosphorus segregation as a consequence of neutron irradiation and post-irradiation thermal annealing at 454°C. One of the A 302 grade B (modified) steels was given the Gleeble treatment, irradiated at 288°C to about 0.8 × 1019n/cm (>1 MeV) and given a thermal annealing treatment at 454°C for 168 h. Charpy impact testing was conducted on the material in both the irradiated and irradiated/annealed conditions, as well as in the as-received condition. The results show that, although the material exhibited a relatively small Charpy impact 41-J temperature shift, the heat-affected zone-simulated material did exhibit significant intergranular fracture in the post-irradiation annealed condition.
Tensile Properties of 12% Cold-Worked Type 316 Stainless Steel Irradiated in EBR-II Under Lower-Dose-Rate Conditions to High Fluence
Authors: Yoshitake T , Donomae T , Mizuta S , Tsai H , Strain RV , Allen TR , Cole JI
Published: April 2008

The effects of lower-dose-rate irradiation on the tensile properties of 12% cold-worked type 316 stainless steel hexagonal ducts which were irradiated in the outer rows of EBR-II were investigated. Tension tests were conducted on a total of seventeen irradiation conditions. Fractographic examinations were performed on four irradiation conditions which were selected based on the results of tension tests. The results of the tension tests and fractographic examinations showed that the 316 stainless steel hexagonal ducts exhibited irradiation hardening typical to 316 stainless steels irradiated at similar temperatures and retained respectable ductility after the irradiation. There was no significant effect of dose rate on tensile properties for the range of irradiation conditions of this study.
Examination of 304L Stainless Steel to 6061-T6 Aluminum Inertia Welded Transition Joints after Irradiation in a Spallation Neutron Spectrum
Authors: Dunn KA , Louthan MR , Mickalonis JI , Maloy S , James MR
Published: April 2008

Tritium target/blanket assemblies were irradiated for six months at the Los Alamos Neutron Science Center (LANSCE). Stainless steel to aluminum inertia weld transition joints were welded to the target/blanket assemblies to simulate expected transition joints in the Accelerator Production of Tritium (APT) where as many as a thousand SS/Al weld transition joints will be used. No leaking at the inertia-welded interface was observed following irradiation. The galvanic interaction at the 6061 Al to 304L stainless steel inertia-welded interface did not present significant degradation as a result of the irradiation or the cooling water chemistry. General corrosion was evident along the entire length of the aluminum piping and pitting corrosion was present along the aluminum piping and is attributed to the conductivity of and the copper deposits in the cooling water. The reduction or elimination of impurities in the cooling water will aid in corrosion control of the aluminum piping.
Sulfosulfuron Efficacy Is Affected by Surfactants, pH of Spray Mixture, and Salts
Authors: Woznica Z , Nalewaja JD , Messersmith CG
Published: April 2008

Sulfosulfuron {1-(4,6-dimethoxypyrimidin-2-yl)-3-[(2-ethanesulfonyl-imidazo[1,2-a]pyridine-3-yl)]sulfonylurea} must be applied with an adjuvant for effective postemergent weed control. Experiments were conducted to determine sulfosulfuron phytotoxicity to green foxtail (Setaria viridis L.) as influenced by surfactant chemistry, surfactant hydrophilic/lipophilic balance (HLB), spray mixture pH, and common nitrogen fertilizers. Regardless of accompanying surfactant chemistry, surfactant HLB, and nitrogen fertilizers, sulfosulfuron efficacy to green foxtail was greatly enhanced when applied in alkaline spray mixture (pH 7.4–8.2) compared to pH 4.0–5.7 unbuffered spray mixture. Secondary alcohol ethoxylate surfactants increased sulfosulfuron efficacy as HLB of these surfactants increased from 8.3 to 17.4 in unbuffered and buffered spray mixtures. The optimum HLB of various block copolymer surfactants for sulfosulfuron was from 9.0 to 13.0. In unbuffered spray mixture, ammonium nitrate at 0.25% w/v had no effect or antagonized sulfosulfuron phytotoxicity, especially when applied with block copolymer surfactants. However, urea fertilizer at 0.25% w/v enhanced herbicide efficacy, regardless of surfactants. Commercial 28% N liquid fertilizer (urea/ammonium nitrate solution) also increased sulfosulfuron efficacy with most surfactants, especially in unbuffered spray mixtures. In spray mixtures buffered above pH 7, the effects of surfactant HLB and nitrogen fertilizers on sulfosulfuron efficacy were less evident. Spray droplet spread and droplet drying time did not relate to sulfosulfuron efficacy.

These data demonstrate a potential for optimizing sulfosulfuron efficacy by carefully selecting surfactant chemistry, surfactant HLB, addition of proper nitrogen fertilizer, and by regulating the pH of the spray mixture.
Adjuvant Effects on Spray Characteristics and Drift Potential
Authors: Miller PCH , Hewitt AJ , Bagley WE
Published: April 2008

This paper describes studies that were conducted to investigate the effects of different surfactant and emulsion adjuvant chemistries and formulations on spray characteristics and drift potential of a commercial herbicide. Previous research has shown that surfactant, emulsion, and polymer adjuvants can affect the formation of sprays and liquid distribution patterns when atomized through flat fan nozzles. The present research involved the application of various different tank mix-adjuvant combinations through flat fan, disc-core, and air induction nozzles. The sprays were characterized using spark photography, droplet size analysis, liquid patternation, and driftability measurements in a wind tunnel. Atomization was related to the physical properties of the tank mixes and sheet breakup mechanisms. The results will help in the development of ASTM test guidelines for spray characterization and drift research, and provide valuable information for applicators to consider when selecting tank mix-nozzle combinations for the application of agricultural chemicals.
Spray Deposition Effect on Abscission Efficacy of CMN-Pyrazole in Harvesting Oranges
Authors: Salyani M , BenSalem E , Whitney JD
Published: April 2008

The objective of this research was to determine the relationship between spray deposition and abscission efficacy of (CMN-Pyrazole), in mechanical harvesting of the ‘Hamlin’ orange. Two tests were conducted on 1/6/00 and 2/11/00 using an air-blast tower sprayer. The sprayer was equipped with an axial-flow fan and hydraulic nozzles. The trees were sprayed at three nozzle arrangements so that 3/4, 1/2, or 1/4 of the total discharge was directed to the upper half of the tree canopy and the rest to the lower half. Spray mixtures, containing CMN-Pyrazole (Release®), adjuvant Kinetic, and a fluorescent tracer, were applied at 2.6 km/h, 3,750 L/ha and 4.0 km/h, 2,450 L/ha, in the first and second tests, respectively. Leaf samples were collected from different canopy locations and spray deposition was quantified by fluorometry. Four to five days after the applications, fruit detachment force (FDF) was measured, dropped fruit was counted, the trees were shaken with a trunk shaker, and percentage of fruit removal was determined.

Mean canopy deposition was similar for all treatments. Deposition at different canopy heights was not proportional to the amount of spray directed to that height. The situation was improved in the second experiment, probably due to the lower application rate and reduced runoff. There was no difference in deposition between two sides of the canopy. Outside canopy deposition was higher than inner canopy deposition in most locations. In general, spray applications were effective in reducing FDF. There was stronger correlation between spray deposition and FDF in the second test. FDF was higher in the upper canopy compared to lower locations in the unsprayed control trees. Fruit removal efficiencies of sprayed trees were significantly higher than those of the unsprayed control in the second test.
Low Dose Urea-Surfactant Adjuvant for Sulfonylurea Herbicides
Authors: Hartmann FDJ , Green JM
Published: April 2008

Urea adducts (urea clathrates) of high molecular weight ethoxylated linear fatty alcohols at low doses are very effective enhancers of sulfonylurea herbicide biological activity. Greenhouse and field trials have identified the preferred alkyl chain length and the degree of ethoxylation for maximum biological efficacy with a broad range of sulfonylurea herbicides at low adjuvant doses. Based on experimental data, the optimum fatty alcohol surfactants include a C16–18 hydrophobe with 25 moles of ethoxylation or a C24 hydrophobe with 13 moles of ethoxylation. However, the latter alcohol ethoxylate is not readily soluble in water while the former dissolves slowly and forms gel phases when mixed into cold water. These characteristics make them generally unsuitable for use as unformulated materials. One readily cold water soluble and commercially available form of this surfactant type which presents very similar performance is based on a C18 linear alcohol ethoxylate with 20 moles of ethoxylation, BRIJ® 78. This ethoxylated linear fatty alcohol remains effective after admixture with related nonionic surfactants and transformation into a readily soluble solid form identified as the urea clathrate of the surfactant.

Urea clathrates can contain between 40–60% of nonionic surfactant by weight while remaining free flowing with melting points above 80 °C. As a result, they can be used as tank-mix or combined with the dry sulfonylurea herbicide formulation. Because of the high activity at low doses, a concentrated dry sulfonylurea herbicide formulation can be achieved with a specific urea clathrate ATPLUS® UCL 1007. Such a combination potentially offers the user more convenience, lower chemical volumes, and reduced costs.
Fretting in Steel Ropes and Cables — A Review
Authors: Waterhouse RB
Published: April 2008

The numerous inter-wire contacts in ropes and cables are potential sites for nucleation of fatigue cracks by fretting. At larger amplitudes of movement excessive wear can occur leading to decreased cross-section of a wire and increased stress, or if debris accumulates, forcing apart of the wires. In locked coil ropes this can cause local stiffness and ingress of corrodants. The wires themselves have an asymmetric residual stress distribution circumferentially resulting from the drawing process. The position of an inter-wire contact relative to this greatly influences the fretting fatigue strength. Hot dip galvanising reduces these stresses as well as giving cathodic protection. Local friction is reduced by incorporating a lubricant in locked coil ropes. Conventional grease-based lubricants with high shear strength are most effective in reducing friction but recent experiments with a lower viscosity oil containing graphite show promise