cssi/SciSciGPT-SciSciNet huggingface dataset:
Routing Apps May Cause Oscillatory Congestions in Traffic Networks

This paper studies the stability of traffic networks when the travelers follow congestion-dependent routing recommendations provided by routing apps. Despite the widespread use of app-based navigation systems, which allow drivers to react in real-time to fluctuations in traffic congestion, a thorough characterization of the benefits and impact of these devices on general and capacitated traffic systems has remained elusive until now. We first propose a dynamical routing model to describe the instantaneous route-update mechanism that is at the core of navigation apps, and then we leverage the theory of passivity for nonlinear dynamical systems to provide a theoretical framework for the analysis of traffic stability. We provide a formal proof of existence of oscillatory trajectories due to the general adoption of routing apps, which demonstrate how drivers continuously switch between highways in the attempt of minimizing their travel time to destination. These findings are used to explain oscillatory behaviors observed in the highway system in Southern California, and inform the design of novel app-based congestion control strategies. Empirical data and illustrative examples demonstrate our theoretical findings.
Fantasy sports participation and the (de)humanization of professional athletes

The dehumanization of professional athletes by sports fans has become a talking point for mainstream media, and fantasy sports participation is in the crosshairs. The social competition and romanti...
Renal Vascular Hypertension

In 1934, Goldblatt and his colleagues placed a band around a single renal artery of a dog and produced hypertension. Of perhaps equal importance was their observation that the hypertension could be reversed by removing the band.1 Four years later, Leadbetter and Burkland performed a nephrectomy on a patient with a small kidney.2 This also led to reversal of the hypertension. Over the past half century, much has been learned concerning the etiology, frequency, and pathophysiology of renal vascular hypertension and several diagnostic and therapeutic modalities have been developed. The purpose of this chapter is to review the more recent advances in this area including our understanding of pathogenesis; our approach as to diagnosis, including the potential utility of digital subtraction angiography and angiotensin competitive antagonists; and the preferred therapy—medical therapy, including converting enzyme inhibitors, surgery, and angioplasty.
Game theory for systems engineering: a survey

Game theory is a useful modelling approach to analyse complex systems with multiple stakeholders, describe their decision-making process, and the impact these decisions have on the overall system performance. In this paper, we review the use of game theory models in the systems engineering domain. Our approach was to conduct an extensive literature review in systems engineering related journals on game theory and systems engineering content. We have identified major application areas of game theory within systems engineering, such as electricity markets, security systems, and supply chain; which we discuss in detail. This paper aggregates notable research to date to provide an overview of the models that have been used to analyse different systems engineering problems. The paper also provides an extensive description of different game properties. This work aims to highlight the potential contribution game theory brings to solving systems engineering problems and its potential for the future.
Targeting Glioblastoma Tumor Microenvironment

Glioblastoma, also referred to as glioblastoma multiforme (GBM), is an aggressive type of brain cancer. The prognosis for GBM is poor with an average medium survival rate of 12–15 months. GBM is highly challenging to treat due to neural stem cells phenotypic variations. These variations are determined by the tumor microenvironment (TME), which refers to all the molecules, cells, and structures that encompass and support other cells and tissues. Along with these, other vital components of the TME are fibroblasts, immune and inflammatory cells, blood and lymphatic vascular networks, extracellular matrix, and signaling molecules. This chapter provides an in-depth review of the vital components that form the TME and methods currently under development attempting to target each key area.
Comparison of quantitative cytomegalovirus antigenemia assay with culture methods and correlation with clinical disease.

Blood samples, obtained predominantly from human immunodeficiency virus-infected patients and solid-organ and bone marrow transplant recipients, were submitted to the clinical laboratory for detection of cytomegalovirus (CMV) and were processed by three methods: conventional culture, centrifugation culture, and CMV antigenemia assay with monoclonal antibodies (Clonab CMV; Biotest Diagnostic Corporation, Denville, N.J.) to CMV antigens. Of 496 blood samples tested, 107 were positive by one or more methods: 56 were positive by conventional culture, 27 were positive by centrifugation culture, and 97 were positive for CMV antigen (Ag) by the antigenemia assay. Forty-seven samples were positive by the CMV antigenemia assay only; in these samples, a mean of 12 Ag-positive cells was detected per 200,000 polymorphonuclear leukocytes examined. In contrast, samples positive by the CMV antigenemia assay and both culture methods had a mean of 193 Ag-positive cells, and samples positive by the CMV antigenemia assay and conventional culture alone had a mean of 157 Ag-positive cells. In the antigenemia assay, paraformaldehyde fixation resulted in superior cell morphology when compared with acetone fixation. Use of immunofluorescence staining reduced sample processing time and the complexity of reagent preparation in comparison with immunoperoxidase staining. Differences in the sensitivities between the immunofluorescence and immunoperoxidase staining techniques for detection of antigenemia were minor, with discrepant samples showing only one or two Ag-positive cells. Clinical disease was generally associated with high-level antigenemia, but exceptions were noted. The CMV antigenemia test is a rapid, quantitative assay that greatly facilitated the rapid diagnosis of CMV infection. However, quantitation of antigenemia is labor-intensive, requires processing of samples soon after collection, and does not always correlate with clinical disease in the individual patient.
Macular oedema in central retinal vein occlusion treated with intravitreal triamcinolone.

. Purpose: To investigate the efficacy of intravitreal triamcinolone as treatment for macular oedema in central retinal vein occlusion (CRVO). Methods: We conducted a retrospective comparative case series of nine patients with macular oedema associated with CRVO (six non-ischaemic and three ischaemic) treated with an intravitreal injection of 4 mg triamcinolone acetonide, compared with 10 control (observation) patients (six non-ischaemic and four ischaemic). Examination included visual acuity (VA) tests and complete ophthalmic examinations at baseline, 1, 2 and 6 months postoperatively. Results: The mean baseline VA was 20/161 for CRVO treatment group patients and 20/75 for observation group patients (p = 0.15). No significant difference in VA between CRVO treatment group patients (20/99) and controls (20/282) was observed at the final 6-month visit (p = 0.33). Subgroup analysis of the non-ischaemic CRVO treatment patients compared with the non-ischaemic controls also showed no significant difference at the 6-month visit (20/59 and 20/100, respectively; p = 0.20). At 6 months, five of the six non-ischaemic treated patients had VA ≥ 20/100, compared with five of the six non-ischaemic control patients. All patients tolerated the procedure well, but there was a significant increase in intraocular pressure by the 2-month visit (p = 0.015). Conclusions: Intravitreal injection of triamcinolone may not be effective for treatment of macular oedema in all CRVO patients or all non-ischaemic CRVO patients. A trend towards VA improvement was noted but was not statistically significant. Although our treatment was not hindered by severe complications, there was a significant increase in IOP in the 2 months following treatment.
Vertex Splines and Their Applications to Interpolation of Discrete Data

It is well known that B-splines in one variable play a central role in the theory of spline functions. However, although there are various generalizations of the notion of B-splines to the multi-variable setting in the literature, very little is known at this writing on the structure and theory of all compactly supported smooth piecewise polynomial functions on a preassigned grid partition Δ in ℝ s , s > 1, unless Δ is perfectly regular. While we don’t have much to offer to the general theory, we will be satisfied with the study of those compactly supported ones with each support containing at least one common vertex and with the interior of the support containing at most one vertex of Δ. These functions are called vertex splines. The objective of this presentation is to give a brief description of the notion of vertex splines and to discuss their applications to interpolation of discrete data with or without constraints.
Photoelectric Measurements of Doublet Intensity Ratios in Cesium

The effects of the spin-orbit perturbation on the alkali fine-structure doublets have a number of manifestations that have been reviewed recently by zu Putlitz.1 These include the non-zero minimum, as a function of energy, of the photoionization cross sections, polarization of the photoelectrons obtained near this cross-section minimum, and the departure, in the discrete spectrum, from the value 2 of the doublet intensity ratio. The value 2 is expected simply on the basis of the ratio of the statistical weights of the excited 2P3/2 and 2P1/2 states. The interest in these phenomena was renewed after the theoretical prediction by Fano,2 based on the perturbation effects by the spin-orbit interaction, that circularly-polarized light could orient the spins of electrons ejected in the photoionization process in cesium. The potential application of the phenomenon to make polarized electron sources was to be exploited soon thereafter.3,4 The two experimental efforts that were thus made to produce polarized electrons, and to measure the degree of polarization, relied on related, but different, techniques. The photoionization results, extrapolated into the discrete spectrum, made different predictions for the behavior of the resonance-line doublet intensity ratios: in one case3 the ratio would pass through a maximum, as the principal quantum number, n, of the excited P states increases toward infinity; in the other4 the ratio would continue to increase as the ionization potential is approached.
3d Hcch-Cosy-Tocsy experiment for the assignment of ribose and amino acid side chains in 13C labeled RNA and protein

A new 3D HCCH-COSY-TOCSY experiment is presented for the assignment of RNA sugar and protein side chains. The experiment, which combines COSY and TOCSY units, is more powerful than the sum of individual HCCH-COSY and HCCH-TOCSY pulse sequences. The experiment was applied to a 13C, 15N-labeled 26 mer RNA complexed with the antibiotic tobramycin, and a 12 kDa 13C, 15N-labeled FKBP12 protein sample. The power of HCCH-COSY-TOCSY is demonstrated through complete spin system assignments of sugars in the 26 mer RNA sample, which could not be assigned using a combination of HCCH-COSY, HCCH-TOCSY and 13C-edited NOESY experiments.
Insect GPCRs and TRP Channels: Putative Targets for Insect Repellents

Many insects such as mosquitoes cause life-threatening diseases such as malaria, yellow fever and West Nile virus. Malaria alone infects 500 million people annually and causes 1-3 million death per year. Volatile insect repellents, which are detected through the sense of smell, have long been used to protect humans against insect pests. Antifeedants are non-volatile aversive compounds that are detected through the sense of taste and prevent insects from feeding on plants. The molecular targets and signaling pathways required for sensing insect repellents and antifeedants are poorly understood.
Ultracentrifuge studies with absorption optics. II. Incorporation of a monochromator and its application to the study of proteins and interacting systems.

Abstract The adaptation of the ultracentrifuge for the incorporation of a monochromator into the absorption optical system is described. This involved raising the ultracentrifuge onto new, higher supports which also provide an adaptable, rigid mount for the monochromator. Remote control knobs and an illuminated panel facilitate the adjustment of the slit width and the wavelength of the light used in the photoelectric scanning absorption system. Procedures for aligning and focusing absorption optical systems are given and different tests are illustrated. These include techniques for determining the correct vertical height of the light source so as to give parallel light through the ultracentrifuge cell, the correct horizontal position of the light source in terms of the optic axis, the appropriate adjustment of the 45 ° mirror of the optical system, and the correct position of the camera lens for focusing on the midplane of the cell. Some of the spurious reflections which plague the absorption system are discussed along with appropriate remedies. The combined monochromator-scanning system is used for determining concentrations, sedimentation coefficients, and spectral properties of proteins. Finally, the optical system is used in both sedimentation velocity and sedimentation equilibrium experiments for the analysis of interactions between colorless macromolecules and small, colored ions and molecules. A sedimentation equilibrium technique of considerable promise for such studies is described and illustrated for a mixture of bovine plasma albumin and methyl orange.
Caregiver characteristics are associated with neuropsychiatric symptoms of dementia.

OBJECTIVES: To determine whether caregiver characteristics are independently associated with neuropsychiatric symptoms of dementia (NPS) after accounting for patient characteristics. DESIGN: Cross-sectional analysis of data from the Medicare Alzheimer's Disease Demonstration and Evaluation study. SETTING: Community-dwelling residents in eight U.S. cities. PARTICIPANTS: Five thousand seven hundred eighty-eight patients with dementia and their caregivers. MEASUREMENTS: Caregivers were asked about the presence of 12 NPS in patients with dementia. Caregiver predictors included age, sex, education, income, marital status, relationship to the patient, whether they lived with patient, number of hours per week spent caregiving, self-reported health, dependency in activities of daily living (ADLs) and instrumental activities of daily living (IADLs), depression, and burden. Multivariate linear regression was used to determine which caregiver characteristics were independently associated with reports of more NPS in patients after controlling for the patient's age, sex, dementia severity, level of ADL dependency, and dementia type. RESULTS: Caregivers were on average 64 years old, 72% female, and 49% were the spouse of the patient (32% wives, 17% husbands). The mean burden score of caregivers was 15 (range 0–32, with higher scores indicating more burden), and 32% had significant depressive symptoms. Patients were on average 79 years old, 60% were female, and most had moderate to severe dementia. The mean number of NPS±standard deviation was 4.8±2.8. After adjusting for patient characteristics, caregivers who were younger, less educated, more depressed, more burdened, or spent more hours per week giving care reported more NPS in care recipients (all P≤.005). CONCLUSION: Certain caregiver characteristics are associated with NPS, independent of patient characteristics, including dementia severity. Clinicians should consider the dynamics between patients and caregivers when managing NPS. Understanding how different caregiver characteristics influence NPS may help tailor caregiver education and interventions.
The Development of “Overconstancy” in Space Perception

Publisher Summary This chapter describes a phenomenon observed in the perceptual functioning of adults—overconstancy. Tracing the developmental history of the formation of this phenomenon should be of relevance for the study of perceptual development generally and for certain theoretical issues arising in this area of behavioral development in particular. Constancy, in visual perception, refers to the tendency for the perceived sizes, shapes, and colors of objects to remain relatively invariant, regardless of changes in the sizes, shapes, or colors of their retinal images—a tendency described as a regression to the real object. On occasions, however, this regression may overshoot the mark, thereby going beyond the real object; the observer may show a bias to perceive an object as distorted in a direction opposite to the one conforming to the retinal image. Such a bias is referred to as overconstancy. It can best be illustrated with reference to the perception of size-at-a-distance, where this phenomenon has been observed most consistently and where it manifests itself through errors of an overestimation of the sizes of objects located far from the observer, relative to the sizes of near objects.
Effect of Dietary α-Linolenic Acid on Growth, Metastasis, Fatty Acid Profile and Prostaglandin Production of Two Murine Mammary Adenocarcinomas

The purpose of this study was to determine whether dietary (n-3) fatty acids would affect mammary tumor growth and metastasis. Weanling female BALB/c mice were fed diets that contained 10% corn oil (CO), linseed oil (LO) or a fish oil-corn oil mix (FO) for 3-8 wk prior to receiving subcutaneous injections of one of two syngeneic mammary tumor cell types (410 and 410.4). Tumor growth was assessed by monitoring mean tumor diameter and tumor weight upon removal. Feeding LO, but not FO, reduced the growth (p less than 0.05) of 410.4 mammary tumors compared with growth in those fed CO. Metastasis data paralleled the tumor growth rate. Feeding LO and FO enhanced (p less than 0.005) incorporation of (n-3) fatty acids into tumors. Tumor prostaglandin E (PGE) production was reduced (p less than 0.005) by LO and FO, compared with CO. FO feeding reduced 410.4 tumor PGE synthesis more (p less than 0.05) than LO feeding, yet tumor growth was only inhibited by LO. These data suggest an inhibitory effect of dietary linolenic acid [i.e., 18:3 (n-3)] on mammary tumor growth and metastasis. However, this effect did not directly correlate with diet-induced changes in PGE synthesis.
Biotinylation of K12 in Histone H4 Decreases in Response to DNA Double-Strand Breaks in Human JAr Choriocarcinoma Cells

We tested the hypothesis that biotinylation of K12 in histone H4 plays a role in the cellular response to double-strand breaks (DSB) of DNA in human cells. DSB were caused by treating choriocarcinoma JAr cells with etoposide. Biotinylation of K12 in histone H4 decreased by 50% as early as 10-20 min after initiation of treatment with etoposide. Biotinylation returned to initial levels 30-40 min after the addition of etoposide to the medium. Temporal patterns of K12-biotinylation were similar for human lymphoma cells. Phosphorylation of S14 of histone H2B and poly(ADP-ribosylation) of glutamate residues on histone H2A are known markers of DSB in DNA; these modifications increased 10-40 min after alterations in K12-biotinylation occurred. Decreased biotinylation of K12 of histone H4 was specific for DSB but was not detectable in response to single-strand breaks or the formation of thymine dimers. Biotin-deficient choriocarcinoma cells exhibited a 40% decrease in rates of survival in response to etoposide compared with biotin-sufficient controls. These studies suggest that the lack of biotinylation of K12 in histone H4 is an early signaling event in response to DSB.
Adaptive modulation of inverters for adjustable speed drives

This paper describes a high performance, high switching frequency modulation method for power inverter applications. The method, adaptive decision tree modulation, is a generalized method of inverter modulation that uses an inductive inference program to create decision tree modulators which emulate modulation strategies that are optimal with respect to a given performance measure. Adaptive decision tree modulation offers a general design approach because an analytical solution of the specified performance measure is not required by the method. Existing inverter modulation methods do not offer the high performance or generality provided by the method. Adaptive decision tree modulators have been demonstrated in simulation and provide performance that is superior to existing discrete pulse modulation methods. >
The nucleation of calcium phosphate from solution

Abstract Dicalcium phosphate was precipitated from homogeneous solution in the pH range 5–6 by using the hydrolysis of cyanate to control the precipitation process. Turbidimetric determination of the onset of precipitation enabled the critical supersaturation to be determined. In this region the average critical supersaturation ratio was found to be 2.3.
NF-κB1 contributes to T cell-mediated control of Toxoplasma gondii in the CNS

In this study, the role of NF-kappaB1 was examined during toxoplasmosis. While wildtype BALB/c mice generated protective responses, NF-kappaB1(-/-) mice developed Toxoplasmic encephalitis, characterized by increased parasite burden and necrosis in the brain. Susceptibility was primarily associated with a local decrease in the number of CD8(+) T cells and IFN-gamma production, while accessory cell function appeared intact in NF-kappaB1(-/-) mice. Consistent with these findings, T cell transfer studies revealed that NF-kappaB1(-/-) T cells provided SCID mice less protection than wildtype T cells. These results demonstrate an intrinsic role for NF-kappaB1 in T cell-mediated immunity to Toxoplasmagondii.
Ge-on-Si Integrated Photonics

We present the latest progress in epitaxial Ge-on-Si lasers, electroabsorption modulators, and photodetectors for integrated photonics. We also discuss an emerging monolithic 3D photonic integration scheme based on high crystallinity GeSn directly grown on SiO2.
Assessment of asbestos burden in the placenta and tissue digests of stillborn infants in South Texas.

The primary aim of this prospective study was to examine the tissues and placentas of autopsied stillborn infants for presence of asbestos fibers. Asbestos burden of lung, liver, skeletal muscle, and placenta digests of 82 stillborn infants was determined using standard bleach digestion technique. The digests were examined by electron microscopy, and the types of fibers determined using energy dispersive x-ray analysis and selected area diffraction analysis. Digests of 45 placentas collected from deliveries of liveborn healthy infants were processed and examined similarly as controls. Asbestos fibers were detected in 50% of the fetal digests and 23% of the placental digests of stillborn infants. Of the fibers present, 88% were chrysotile, 10% were tremolite, and 2% were actinolite and anthophyllite. Fibers measured 0.5–16.73 μm in length (mean 1.55 μm), and 0.03–0.8 μm in width (mean 0.098 μm). Lungs were most frequently positive for fibers (50%), followed by muscle (37%), placenta (23%), and liver (23%). Mean fiber counts were highest in the liver (58,736 f/g), followed by placenta (52,894 f/g), lungs (39,341 f/g), and skeletal muscle (31,733 f/g). Digests of 15% of the control placentas also showed asbestos fibers, although in very small numbers. The mean fiber count of the stillborn placentas (52,894 f/g) was significantly higher than the mean fiber count of the control placentas (mean 19 f/g) (p = 0.001). A highly significant association was found between fiber presence in stillborns and a maternal history of previous abortions (p = 0.007). A significant association was also found between fiber presence and placental diseases (p = 0.041). An association was suggested between working mothers and fiber presence (p = 0.19), although it did not reach statistical significance. The study documents the presence of small and thin asbestos fibers in stillborn fetal tissues and placenta. Significantly higher number of fibers were found in stillborn tissues compared to controls (liveborn placenta). The absence of a maternal history of asbestos-related occupations suggests that the fibers may have been acquired through environmental exposure.
IMPROVED YIELDS OF BOVINE BLASTOCYSTS FROM IN VITRO-PRODUCED OOCYTES. I: SELECTION OF OOCYTES AND ZYGOTES

Abstract Three experiments were conducted with 7,901 oocytes (6,152 cleaved zygotes) to identify methods to increase the proportion of oocytes aspirated from ovaries of slaughtered cows that would develop to expanded blastocysts by 9 d after exposure to spermatozoa. In the first experiment, oocytes were matured for 24 h in TCM-199, fertilized, and presumptive zygotes were co-cultured in TCM-199 and granulosa cells. Cleaved zygotes from oocytes classified as good on the basis of quality of investments and cytoplasm developed to expanded blastocysts more frequently than did zygotes from intermediate-marginal oocytes (29% vs 24%; P=0.035). In the second experiment, marginal oocytes were subdivided into those with partially expanded cumulus, coarsely granulated cytoplasm or minimal cumulus (not more than 3 layers of cumulus cells, or zona pellucida partly exposed), matured in Ham's F-10, and co-cultured in Menezo's B2 with buffalo rat liver (BRL) cells. Cleaved zygotes from oocytes with partially expanded cumulus and/or coarsely granulated cytoplasm developed to expanded blastocysts as frequently (47%) as did good/intermediate oocytes (40%), but zygotes from oocytes with minimal cumulus developed less frequently (23%; P
Covariant space-time operators, infinite-component wavefunctions, and proper-time Schrödinger equations

Abstract A covariant form for the classical Poisson bracket formulation for the motion of a charged particle in an electromagnetic field is introduced by using proper time instead of real time and using the mass as a dynamical variable which takes the place of the Hamiltonian. In this form the time is a dynamical variable at the same level as the coordinates. The theory is then quantized by replacing Poisson brackets by commutators in the usual way. All Hermitian realizations of the set of dynamical variables are found, the set consisting of the space-time dynamical variables, the four-momentum, and the relativistic angular momentum tensor. The wavefunction is either a scalar wavefunction or it has an infinite number of components. Thus treating time as an operator leads to infinite-component wavefunctions. It is then shown how the wavefunctions of these realizations can be reduced to an integral over modes which transform under irreducible unitary representations of the Poincare group which involve imaginary mass components as well as real mass components. Finally, it is shown how a proper time Schrodinger equation is obtained from the unquantized covariant theory by treating the mass as an operator.
Early Postoperative Outcomes and Blood Product Utilization in Adult Cardiac Surgery The Post-Aprotinin Era

Background— Aprotinin was a commonly used pharmacological agent for homeostasis in cardiac surgery but was discontinued, resulting in the extensive use of lysine analogues. This study tested the hypothesis that early postoperative adverse events and blood product utilization would affected in this post-aprotinin era. Methods and Results— Adult patients (n=781) undergoing coronary artery bypass, valve replacement, or both from November 1, 2005, to October 31, 2008, at a single institution were included. Multiple logistic regression modeling and propensity scoring were performed on 29 preoperative and intraoperative variables in patients receiving aprotinin (n=325) or lysine analogues (n=456). The propensity-adjusted relative risk (RR) for the intraoperative use of packed red blood cells (RR, 0.75; 95% confidence interval [CI], 0.57 to 0.99), fresh frozen plasma (RR, 0.37; 95% CI, 0.21 to 0.64), and cryoprecipitate (RR:0.06; 95% CI, 0.02 to 0.22) were lower in the aprotinin versus lysine analog group (all P <0.05). The risk for mortality (RR, 0.53; 95% CI, 0.16 to 1.79) and neurological events (RR, 0.87; 95% CI, 0.35 to 2.18) remained similar between groups, whereas a trend for reduced risk for renal dysfunction was observed in the aprotinin group. Conclusions— In the post-aprotinin era, with the exclusive use of lysine analogues, the relative risk of early postoperative outcomes such as mortality and renal dysfunction have not improved, but the risk for the intraoperative use of blood products has increased. Thus, improvements in early postoperative outcomes have not been realized with the discontinued use of aprotinin, but rather increased blood product use has occurred with the attendant costs and risks inherent with this strategy.
Cloud droplet nucleation by crude oil smoke and coagulated crude oil/wood smoke particles

Abstract Cloud condensation nuclei (CCN) measurements are reported, taken on smoke aerosol particle samples generated from the combustion of small quantities of high- and low-sulfur crude oils. The smoke samples were stored in 6 m3 aging bags, and were analyzed over aging times of more than 50 h. Up to 58% of the high-sulfur crude oil smoke particles were found to be active as CCN at water supersaturation of 1% or less, while 20% were active in the low-sulfur case. Ion chromatography data show the presence of small quantities of inorganic and organic compounds which may be the cause of the CCN activity. The low-sulfur crude oil smoke particles were mixed with wood smoke particles, to see if the resulting aggregates are active as CCN.
Determination of aromatic hydrocarbon fraction in oil shale by 13C n.m.r. with magic-angle spinning

Abstract A method for estimation of aromatic content in oil shales is demonstrated. Magic-angle spinning at 2 kHz is shown to remove chemical shift anisotropy to a sufficient degree to resolve aromatic and aliphatic 13 C n.m.r. spectral regions for a lithic oil shale specimen. The proton and carbon n.m.r. relaxation parameters are such as to allow room-temperature use of this proton-enhanced 13 C n.m.r. technique as a quantitative analytical tool. Cross polarization times of a millisecond or less and experiment repetition periods of 0.5 s or less are optimum. The specimen examined is represented by an aromatic carbon fraction 0.264 ± 0.007; this determination is quite insensitive to the proton-carbon cross polarization time. Spectra for kerogen, shale oil, and dawsonite are also presented. Dawsonite may interfere in the determination of the aromatic fraction.