CHARACTERIZATION OF PETROLEUM RESIDUA THROUGH REDUCTIVE CHEMISTRY

ABSTRACT

Distillation residua from petroleum, containing 26 — 32% aromatic carbon (f_a), are reduced by K⁰ in tetrahydrofuran to form anions which are then alkylated by alkyl iodides. Consumption of potassium in 24 hours at room temperature is in the range 4 to 5 mmol K per gram resid, of which 19—23% goes to the formation of “K₂S” from the removal of sulfur from the resid. The anions of the resid are characterized by alkylation of the resid with ¹³C enriched methyl iodide followed by examination by heteronuclear correlated two—dimensional nuclear magnetic resonance of ¹H and ¹³C spins. Analysis of proton and carbon shifts of individual methyls demonstrates that attachment of methyls to carbon atoms of the resid is the principal chemistry of the reductive methylation.     

Application of the Water Poverty Index at Different Scales: A Cautionary Tale

Abstract

The Water Poverty Index is an integrated tool developed on the basis of extensive consultation with a range of scientists, practitioners and policymakers. It is primarily designed for use at the community level to enable more holistic water-resource assessments on a site-specific basis. It can however be applied at different scales to suit different needs. One of the motivations to design such a tool was an attempt to move away from the conventional, purely deterministic, approaches to water assessment, relying primarily on models and large-scale data. In today's world such an approach is inappropriate, ill representing the complexities of modern water-allocation decisions where economic, political and social issues all have a powerful role to play. This paper highlights some applications of the Water Poverty Index at different spatial scales and discusses the implications of applying indicators at these different scales.     

Hypolimnetic redox and phosphorus cycling in hypereutrophic Lake Sebasticook, Maine

The vertical distribution of reduced species and phosphate was monitored throughout a summer stagnation period in hypereutrophic Lake Sebasticook, Maine. The oxygen demand of reduced species released from hypolimnetic sediments was dominated by methane, followed by ammonium, and included minor contributions from Fe²⁺, Mn²⁺ and sulfide. Release of iron and manganese from the sediments was apparently controlled by dissolution of siderite and rhodochrosite, with the requisite acidity for the dissolution provided by methanogenesis. Redox recycling of these two metals occurs in two vertically displaced “wheels”, which enhance oxidant delivery to the hypolimnion beyond that provided by oxygen diffusion alone. Phosphorus is tightly coupled to the “ferrous wheel”, in the absence of wind events, and is scavenged with a stoichiometry consistent with Tessenow's (Tessenow U., Arch. Hydrobiol.Suppl. 47, 1–79, 1974) laboratory studies.     

Luteinization of porcine preovulatory follicles leads to systematic changes in follicular gene expression

The LH surge initiates the luteinization of preovulatory follicles and causes hormonal and structural changes that ultimately lead to ovulation and the formation of corpora lutea. The objective of the study was to examine gene expression in ovarian follicles (n = 11) collected from pigs (Sus scrofa domestica) approaching estrus (estrogenic preovulatory follicle; n = 6 follicles from two sows) and in ovarian follicles collected from pigs on the second day of estrus (preovulatory follicles that were luteinized but had not ovulated; n = 5 follicles from two sows). The follicular status within each follicle was confirmed by follicular fluid analyses of estradiol and progesterone ratios. Microarrays were made from expressed sequence tags that were isolated from cDNA libraries of porcine ovary. Gene expression was measured by hybridization of fluorescently labeled cDNA (preovulatory estrogenic or -luteinized) to the microarray. Microarray analyses detected 107 and 43 genes whose expression was decreased or increased (respectively) during the transition from preovulatory estrogenic to -luteinized (P<0.01). Cells within preovulatory estrogenic follicles had a gene-expression profile of proliferative and metabolically active cells that were responding to oxidative stress. Cells within preovulatory luteinized follicles had a gene-expression profile of nonproliferative and migratory cells with angiogenic properties. Approximately, 40% of the discovered genes had unknown function.     

A tale of two Great Lakes conferences: Urging global collaboration on our largest freshwater resources

Scientific meetings and conferences are a part of the scientific process, and can facilitate collaboration, idea-sharing, and harmonization of research and management. The success of a conference can be measured using many criteria, including consistency and reoccurrence of the meetings, credibility by participation of reputable professionals, and attendance by a diverse community. In the interest of increasing the success of large-lake, freshwater science, policy, and management, this comment focuses on two recent conferences attended by the authors: the 60th annual meeting of the International Association for Great Lakes Research, in Detroit, U.S.A., and the African Great Lakes Conference, in Entebbe, Uganda. By our measures of success, we suggest that to make a larger impact on research, policy, and management of global, large, freshwater lakes that each conference can improve, either through greater diversity of experts from the global freshwater research community, or by consistently reoccurring on a regular basis.     

Agriculture and food quality and safety certification agencies in four Chinese cities

Investigations of certification agencies were conducted in four Chinese cities: Guangzhou, Shenzhen, Hangzhou and Qingdao. Based on an analysis of the data and information obtained, the status and character of agro-food certification in China were assessed. The main obstacle for development of agro-food certification was identified as the lack of market acceptance for it. In conclusion, the paper provides some suggestions for improving agro-food certification in China.     

Effect of initial joint position on nerve-cuff recordings of muscleafferents in rabbits

The objective was to characterize nerve-cuff recordings of muscle afferents to joint rotation over a large part of the physiological joint range. This information is needed to develop control strategies for functional electrical stimulation (FES) systems using muscle afferent signals for sensory feedback. Five acute rabbit experiments were performed. Tripolar cuff electrodes were implanted around the tibial and peroneal divisions of the sciatic nerve in the rabbit's left leg. The electroneurograms (ENG) were recorded during passive ankle rotation, using a ramp-and-hold profile starting at seven different joint positions (excursion=5°, velocity=10°/s, initial positions 60°, 70°, 80°, 90°, 100°, 110°, and 120°). The amplitude of the afferent activity was dependent on the initial joint position. The steady-state sensitivity of both nerve responses increased with increasing joint flexion, whereas the dynamic sensitivity increased initially but then decreased. The results indicate that recordings of the muscle afferents may provide reliable information over only a part of the physiological joint range, Despite this limitation, muscle afferent activity may be useful for motion feedback if the movement to be controlled is within a narrow joint range such as postural sway     

Issues in defining and assessing features of attachment figures: Reply to Kobak (2009).

This reply to Kobak’s (see record 2009-12106-002) comments on my article (see record 2009-12106-001) on dogs as attachment figures addresses three issues in defining and assessing features of attachment figures. These include whether some features are more critical than other features, different ways of assessing safe haven as a critical feature of an attachment figure, and whether attachment hierarchies are necessary to identify figures who fulfill the feature of safe haven. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Improving the Accuracy and Reliability of Remote System-Calibration-Free Eye-Gaze Tracking

Remote eye-gaze tracking provides a means for nonintrusive tracking of the point-of-gaze (POG) of a user. For application as a user interface for the disabled, a remote system that is noncontact, reliable, and permits head motion is very desirable. The system-calibration-free pupil-corneal reflection (P-CR) vector technique for POG estimation is a popular method due to its simplicity, however, accuracy has been shown to be degraded with head displacement. Model-based POG-estimation methods were developed, which improve system accuracy during head displacement, however, these methods require complex system calibration in addition to user calibration. In this paper, the use of multiple corneal reflections and point-pattern matching allows for a scaling correction of the P-CR vector for head displacements as well as an improvement in system robustness to corneal reflection distortion, leading to improved POG-estimation accuracy. To demonstrate the improvement in performance, the enhanced multiple corneal reflection P-CR method is compared to the monocular and binocular accuracy of the traditional single corneal reflection P-CR method, and a model-based method of POG estimation for various head displacements.