Numerical investigation of effects of addition of ethanol to gasoline on Laminar Flame Speed (LFS), autoignition, and wall quenching

Since the advent of automobiles, alcohol has been considered a possible engine fuel1,2. With the recent increased concern about the high price of crude oil due to fluctuating supply and demand and environmental issues, interest in alcohol based fuels has increased2,3. However, using pure alcohols or blends with conventional fuels in high percentages requires changes to the engine and fuel system design2. This leads to the need for a simple and accurate conventional fuels-alcohol blends combustion models that can be used in developing parametric burn rate and knock combustion models for designing more efficient Spark Ignited (SI) engines. To contribute to this understanding, numerical simulations were performed to obtain detailed characteristics of Gasoline-Ethanol blends with respect to Laminar Flame Speed (LFS), autoignition and Flame-Wall interactions. The one-dimensional premixed flame code CHEMKIN® was applied to simulate the burning velocity and autoignition characteristics using the freely propagating model and closed homogeneous reactor model respectively. Computational Fluid Dynamics (CFD) was used to obtain detailed flow, temperature, and species fields for Flame-wall interactions. A semi-detailed validated chemical kinetic model for a gasoline surrogate fuel developed by Andrae and Head4 was used for the study of LFS and Autoignition. For the quenching study, a skeletal chemical kinetic mechanism of gasoline surrogate, having 50 species and 174 reactions was used. The surrogate fuel was defined as a mixture of pure n-heptane, isooctane, and toluene. For LFS study, the ethanol volume fraction was varied from 0 to 85%, initial pressure from 4 to 8 bar, initial temperature from 300 to 900K, and dilution from 0 to 32%. Whereas for Autoignition study, the ethanol volume fraction was varied between 0 to 85%, initial pressure was varied between 20 to 60 bar, initial temperature was varied between 800 to 1200K, and the dilution was varied between 0 to 32% at equivalence ratios of 0.5, 1.0 and 1.5 to represent the in-cylinder conditions of a SI engine. For quenching study three Ethanol blends, namely E0, E25 and E85 are described in detail at an initial pressure of 8 atm and 17 atm. Initial wall temperature was taken to be 400 K. Quenching thicknesses and heat fluxes to the wall were computed. The laminar flame speed was found to increase with ethanol concentration and temperature but decrease with pressure and dilution. The autoignition time was found to increase with ethanol concentration at lower temperatures but was found to decrease marginally at higher temperatures. The autoignition time was also found to decrease with pressure and equivalence ratio but increase with dilution. The average quenching thickness was found to decrease with an increase in Ethanol concentration in the blend. Heat flux to the wall increased with increase in ethanol percentage in the blend and at higher initial pressures. Whereas the wall heat flux decreased with an increase in dilution. Unburned Hydrocarbon (UHC) and CO % was also found to decrease with ethanol concentration in the blend.

Modulation of parvalbumin expression in the motor cortex of parkinsonian rats

Dopamine deficiency in Parkinson's disease leads to numerous molecular changes in basal ganglia. However, the consequences of these changes on the motor cortex remain unclear. Here we show that the immunoreactivity of parvalbumin, which is expressed in GABAergic interneurons, increases in the primary motor cortex of parkinsonian rats. This increase can be reversed by a subsequent lesion of the subthalamic nucleus. These results suggest that dopamine deficiency induces reversible changes in GABAergic cortical cells, which might be linked with parkinsonian symptoms.

Modulation of nociceptive withdrawal reflexes evoked by single and repeated nociceptive stimuli in conscious dogs by low-dose acepromazine

OBJECTIVES: To investigate the modulation of the nociceptive withdrawal reflex (NWR) and temporal summation (TS) by low-dose acepromazine (ACP) in conscious dogs. To assess the short- and long-term stability of the reflex thresholds. STUDY DESIGN: Randomized, blinded, placebo-controlled cross-over experimental study. ANIMALS: Eight adult male Beagles. METHODS: The NWR was elicited using single transcutaneous electrical stimulation of the ulnar nerve. Repeated stimuli (10 pulses, 5 Hz) were applied to evoke TS. The responses of the deltoideus muscle were recorded and quantified by surface electromyography and the behavioural reactions were scored. Each dog received 0.01 mg kg(-1) ACP or an equal volume saline intravenously (IV) at 1 week intervals. Measurements were performed before (baseline) and 20, 60 and 100 minutes after drug administration. Sedation was scored before drug administration and then at 10 minutes intervals. Data were analyzed with Friedman repeated measures analysis of variance on ranks and Wilcoxon signed rank tests. RESULTS: Acepromazine resulted in a mild tranquilization becoming obvious at 20 minutes and peaking 30 minutes after injection. Single (I(t)) and repeated stimuli (TS(t)) threshold intensities, NWR and TS characteristics and behavioural responses were not affected by the ACP at any time point. Both I(t) and TS(t) were stable over time. CONCLUSIONS AND CLINICAL RELEVANCE: In dogs, 0.01 mg kg(-1) ACP IV had no modulatory action on the NWR evoked by single or repeated stimuli, suggesting no antinociceptive activity on phasic nociceptive stimuli. The evidence of the stability of the NWR thresholds supports the use of the model as an objective tool to investigate nociception in conscious dogs. A low dose of ACP administered as the sole drug, can be used to facilitate the recordings in anxious subjects without altering the validity of this model.

A novel rare variant in SCN1Bb linked to Brugada syndrome and SIDS by combined modulation of Na(v)1.5 and K(v)4.3 channel currents.

BACKGROUND Cardiac sodium channel β-subunit mutations have been associated with several inherited cardiac arrhythmia syndromes. OBJECTIVE To identify and characterize variations in SCN1Bb associated with Brugada syndrome (BrS) and sudden infant death syndrome (SIDS). METHODS All known exons and intron borders of the BrS-susceptibility genes were amplified and sequenced in both directions. Wild type (WT) and mutant genes were expressed in TSA201 cells and studied using co-immunoprecipitation and whole-cell patch-clamp techniques. RESULTS Patient 1 was a 44-year-old man with an ajmaline-induced type 1 ST-segment elevation in V1 and V2 supporting the diagnosis of BrS. Patient 2 was a 62-year-old woman displaying a coved-type BrS electrocardiogram who developed cardiac arrest during fever. Patient 3 was a 4-month-old female SIDS case. A R214Q variant was detected in exon 3A of SCN1Bb (Na(v)1B) in all three probands, but not in any other gene previously associated with BrS or SIDS. R214Q was identified in 4 of 807 ethnically-matched healthy controls (0.50%). Co-expression of SCN5A/WT + SCN1Bb/R214Q resulted in peak sodium channel current (I(Na)) 56.5% smaller compared to SCN5A/WT + SCN1Bb/WT (n = 11-12, P<0.05). Co-expression of KCND3/WT + SCN1Bb/R214Q induced a Kv4.3 current (transient outward potassium current, I(to)) 70.6% greater compared with KCND3/WT + SCN1Bb/WT (n = 10-11, P<0.01). Co-immunoprecipitation indicated structural association between Na(v)β1B and Na(v)1.5 and K(v)4.3. CONCLUSION Our results suggest that R214Q variation in SCN1Bb is a functional polymorphism that may serve as a modifier of the substrate responsible for BrS or SIDS phenotypes via a combined loss of function of sodium channel current and gain of function of transient outward potassium current.

Spatial modulation of primate inferotemporal responses by eye position.

BACKGROUND: A key aspect of representations for object recognition and scene analysis in the ventral visual stream is the spatial frame of reference, be it a viewer-centered, object-centered, or scene-based coordinate system. Coordinate transforms from retinocentric space to other reference frames involve combining neural visual responses with extraretinal postural information. METHODOLOGY/PRINCIPAL FINDINGS: We examined whether such spatial information is available to anterior inferotemporal (AIT) neurons in the macaque monkey by measuring the effect of eye position on responses to a set of simple 2D shapes. We report, for the first time, a significant eye position effect in over 40% of recorded neurons with small gaze angle shifts from central fixation. Although eye position modulates responses, it does not change shape selectivity. CONCLUSIONS/SIGNIFICANCE: These data demonstrate that spatial information is available in AIT for the representation of objects and scenes within a non-retinocentric frame of reference. More generally, the availability of spatial information in AIT calls into questions the classic dichotomy in visual processing that associates object shape processing with ventral structures such as AIT but places spatial processing in a separate anatomical stream projecting to dorsal structures.

Dopaminergic modulation of the reward system in schizophrenia: A placebo-controlled dopamine depletion fMRI study

Background The brain reward circuitry innervated by dopamine is critically disturbed in schizophrenia. This study aims to investigate the role of dopamine-related brain activity during prediction of monetary reward and loss in first episode schizophrenia patients. Methods We measured blood–oxygen-level dependent (BOLD) activity in 10 patients with schizophrenia (SCH) and 12 healthy controls during dopamine depletion with α-methylparatyrosine (AMPT) and during a placebo condition (PLA). Results AMPT reduced the activation of striatal and cortical brain regions in SCH. In SCH vs. controls reduced activation was found in the AMPT condition in several regions during anticipation of reward and loss, including areas of the striatum and frontal cortex. In SCH vs. controls reduced activation of the superior temporal gyrus and posterior cingulate was observed in PLA during anticipation of rewarding stimuli. PLA patients had reduced activation in the ventral striatum, frontal and cingulate cortex in anticipation of loss. The findings of reduced dopamine-related brain activity during AMPT were verified by reduced levels of dopamine in urine, homovanillic-acid in plasma and increased prolactin levels. Conclusions Our results indicate that dopamine depletion affects functioning of the cortico-striatal reward circuitry in SCH. The findings also suggest that neuronal functions associated with dopamine neurotransmission and attribution of salience to reward predicting stimuli are altered in schizophrenia.

Progenitor cells as remote "bioreactors": Neuroprotection via modulation of the systemic inflammatory response.

Acute central nervous system (CNS) injuries such as spinal cord injury, traumatic brain injury, autoimmune encephalomyelitis, and ischemic stroke are associated with significant morbidity, mortality, and health care costs worldwide. Preliminary research has shown potential neuroprotection associated with adult tissue derived stem/progenitor cell based therapies. While initial research indicated that engraftment and transdifferentiation into neural cells could explain the observed benefit, the exact mechanism remains controversial. A second hypothesis details localized stem/progenitor cell engraftment with alteration of the loco-regional milieu; however, the limited rate of cell engraftment makes this theory less likely. There is a growing amount of preclinical data supporting the idea that, after intravenous injection, stem/progenitor cells interact with immunologic cells located in organ systems distant to the CNS, thereby altering the systemic immunologic/inflammatory response. Such distant cell "bioreactors" could modulate the observed post-injury pro-inflammatory environment and lead to neuroprotection. In this review, we discuss the current literature detailing the above mechanisms of action for adult stem/progenitor cell based therapies in the CNS.

Dietary factors in the modulation of inflammatory bowel disease activity.

CONTEXT: As patients look to complementary therapies for management of their diseases, it is important that the physician know the effectiveness and/or lack of effectiveness of a variety of dietary approaches/interventions. Although the pathogenesis of the inflammatory bowel diseases (ulcerative colitis and Crohn's disease) is not fully understood, many suspect that diet and various dietary factors may play a modulating role in the disease process. EVIDENCE ACQUISITION: The purpose of this article is to present some of what is known about various dietary/nutritional factors in inflammatory bowel disease, with inclusion of evidence from various studies regarding their putative effect. MedLINE was searched (1965-present) using combinations of the following search terms: diet, inflammatory bowel disease, Crohn's disease, and ulcerative colitis. Additionally, references of the articles obtained were searched to identify further potential sources of information. EVIDENCE SYNTHESIS: While much information is available regarding various dietary interventions/supplements in regard to inflammatory bowel disease, the lack of controlled trials limits broad applicability. Probiotics are one of the few interventions with promising results and controlled trials. CONCLUSION: While there are many potential and promising dietary factors that may play a role in the modulation of inflammatory bowel disease, it is prudent to await further controlled studies before broad application/physician recommendation in the noted patient population.

IMMUNE MODULATION OF THE MYCOBACTERIUM TUBERCULOSIS GRANULOMATOUS RESPONSE

Tuberculosis (TB) remains a major public health burden. The immunocompetant host responds to Mycobacterium tuberculosis (MTB) infection by the formation of granulomas, which initially prevent uncontrolled bacterial proliferation and dissemination. However, increasing evidence suggests that granuloma formation promotes persistence of the organism by physically separating infected cells from effector lymphocytes and by inducing a state of non-replicating persistence in the bacilli, making them resistant to the action of antibiotics. Additionally, immune-mediated tissue destruction likely facilitates disease transmission. The granulomatous response is in part due to mycobacterial glycolipid antigens. Therefore, studies were first undertaken to determine the innate mechanisms of mycobacterial cord factor trehalose-6’6-dimycolate (TDM) on granuloma formation. Investigations using knock-out mice suggest that TNF-a is involved in the initiation of the granulomatous response, complement factor C5a generates granuloma cohesiveness, and IL-6 is necessary for maintenance of an established granulomatous responses. Studies were next performed to determine the ability of lactoferrin to modulate the immune response and pathology to mycobacterial cord factor. Lactoferrin is an iron-binding glycoprotein with immunomodulatory properties that decrease tissue damage and promote Th1 responses. Mice challenged with TDM and treated with lactoferrin had decreased size and numbers of granulomas at the peak of the granulomatous response, accompanied by increased IL-10 and TGF-b production. Finally, the ability of lactoferrin to serve as a novel therapeutic for the treatment of TB was performed by aerosol challenging mice with MTB and treating them with lactoferrin added to the drinking water. Mice given tap water had lung log10 CFUs of 7.5 ± 0.3 at week 3 post-infection. Lung CFUs were significantly decreased in mice given lactoferrin starting the day of infection (6.4 ± 0.7) and mice started therapeutically on lactoferrin at day 7 after established infection (6.5 ± 0.4). Total lung inflammation in lactoferrin treated mice was significantly decreased, with fewer areas of macrophages, increased total lymphocytes, and increased numbers of CD4+ and CD8+ cells. The lungs of lactoferrin treated mice had increased CD4+ IFN-g+ cells and IL-17 producing cells on ELISpot analysis. It is hypothesized that lactoferrin decreases bacterial burden during MTB infection by early induction of Th1 responses.