Parametric optimization and performance analysis of a waste heat recovery system based on Organic Rankine Cycle, using R-12, R-123 and R-134a as working fluids for power generation have been studied. ...The cycles are compared with heat source as waste heat of flue gas at 140 °C and 312 Kg/s/unit mass flow rate at the exhaust of ID fans for 4 × 210 MW, NTPC Ltd. Kahalgaon, India. Optimization of turbine inlet pressure for maximum work and efficiencies of the system along the saturated vapour line and isobaric superheating at different pressures has been carried out for the selected fluids. The results show that R-123 has the maximum work output and efficiencies among all the selected fluids. The Carnot efficiency for R-123 at corrected pressure evaluated under similar conditions is close to the actual efficiency. It can generate 19.09 MW with a mass flow rate of 341.16 Kg/s having a pinch point of 5 °C, First law efficiency of 25.30% and the Second law efficiency of 64.40%. Hence selection of an Organic Rankine Cycle with R-123 as working fluid appears to be a choice system for utilizing low-grade heat sources for power generation.
The removal of Bisphenol-A (BPA) from contaminated water using advanced oxidation methods such as UV-C assisted oxidation by hydrogen peroxide (H2O2) and sodium persulfate (SPS) has been reported by ...the authors earlier (Sharma et al., 2015a). In the present study, the authors report the removal of BPA from aqueous solution by the above two methods and its degradation mechanism. UV-C light (254 nm wavelength, 40 W power) was applied to BPA contaminated water at natural pH (pHN) under room temperature conditions. Experiments were carried out with the initial BPA concentration in the range of 0.04 mM–0.31 mM and the oxidant/BPA molar ratio in the range of 294:1–38:1 for UV-C/H2O2 and 31.5–4.06:1 for UV-C/SPS systems. The removal of BPA enhanced with decreasing BPA concentration. The total organic carbon also decreased with the UV-C irradiation time under optimum conditions (H2O20 = 11.76 mM; SPS0 = 1.26 mM; temperature (29 ± 3 °C). Competition of BPA for reaction with HO or SO4·− radicals at its higher concentrations results in a decrease in the removal of BPA. The intermediates with smaller and higher molecular weights than that of BPA were found in the treated water. Based on GC-MS and FTIR spectra of the reaction mixture, the formation of hydroxylated by-products testified the HO mediated oxidation pathway in the BPA degradation, while the formation of quinones and phenoxy phenols pointed to the SO4·− dominating pathway through the formation of hydroxycyclohexadienyl (HCHD) and BPA phenoxyl radicals. The main route of BPA degradation is the hydroxylation followed by dehydration, coupling and ring opening reactions.
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•Sulfate radicals (SO4·−) are more efficient in Bisphenol A (BPA) oxidation.•Quinones via SO4·− and hydroxylated byproducts are found via HO radicals attack.•Intermediates detected have lower and higher molecular weights than BPA.•Hydroxylation, oxidation, ring-opening, coupling reactions form the possible pathways.•Brown solid particles indicate the formation of coupling products in UV-C/SPS system.
► Analysis of ORC using R-12, R-123, R-134a and R-717 with isobaric superheating. ► Examined performances under fixed and variable heat source temperature conditions. ► For variable heat source, the ...temperature of heat source is kept 15
K above TIT. ► Compared efficiencies, irreversibility, work output etc. with increase in TIT. ► R-123 produces the maximum efficiencies with minimum irreversibility.
This paper presents an analysis of non-regenerative Organic Rankine Cycle (ORC), based on the parametric optimization, using R-12, R-123, R-134a and R-717 as working fluids superheated at constant pressure. A computer programme has been developed to parametrically optimize and compare the system and second law efficiency, irreversibility of the system, availability ratio, work output, mass flow rate with increase in turbine inlet temperature (TIT) under different heat source temperature conditions. The calculated results reveal that R-123 produces the maximum efficiencies and turbine work output with minimum irreversibility for employed constant as well as variable heat source temperature conditions. Hence, selection of a non-regenerative ORC during superheating using R-123 as working fluid appears to be a choice system for converting low-grade heat to power.
Emission properties of compact astrophysical objects such as Neutron stars (NSs) are associated with crucial astronomical observables. In the current work, we obtain the mass, pressure profiles of ...the non-rotating NSs using the modified Tolman Oppenheimer Volkoff (TOV) system of equations in the presence of intense magnetic field. We obtain the profiles by using a specific distance-dependent magnetic field in the modified TOV equations. We employ three different equations of states (EoS) to solve the TOV equations by assuming the core of NSs comprises a hadronic matter. Employing the above profiles, we determine the cooling rates of spherically symmetric NSs as a function of time with and without including the magnetic field using the NSCool code. We have also determined the cooling rates as a function of radius for three different NSs. Furthermore, we determine the luminosity of neutrinos, axions, and photons emitting from the NSs in the presence and absence of a magnetic field for an axion mass 16 meV and three different EoS. Our comparative study indicates that the cooling rate and luminosities of neutrinos, axions, and photons change significantly due to the impact of the strong magnetic field. We also find that due to the magnetic field, the axion mass bound increases slightly compared to without a magnetic field.
Impaired consciousness in temporal lobe seizures has a major negative impact on quality of life. The prevailing view holds that this disorder impairs consciousness by seizure spread to the bilateral ...temporal lobes. We propose instead that seizures invade subcortical regions and depress arousal, causing impairment through decreases rather than through increases in activity. Using functional magnetic resonance imaging in a rodent model, we found increased activity in regions known to depress cortical function, including lateral septum and anterior hypothalamus. Importantly, we found suppression of intralaminar thalamic and brainstem arousal systems and suppression of the cortex. At a cellular level, we found reduced firing of identified cholinergic neurons in the brainstem pedunculopontine tegmental nucleus and basal forebrain. Finally, we used enzyme-based amperometry to demonstrate reduced cholinergic neurotransmission in both cortex and thalamus. Decreased subcortical arousal is a critical mechanism for loss of consciousness in focal temporal lobe seizures.
•Subcortical arousal nuclei show decreased fMRI signals in focal seizures•Seizures suppress cholinergic neurons in the brainstem and basal forebrain•Amperometry reveals decreased acetylcholine in the cortex and thalamus•Mechanism of loss of consciousness in focal seizures resembles slow-wave sleep
Intense increased firing of neurons is commonly thought to disrupt brain function in epilepsy. Motelow et al. demonstrate instead that decreased activity in subcortical arousal systems leads to depressed cortical function and impaired consciousness in focal seizures.
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Pediatric population is a sensitive sector of the healthcare and pharmaceutical field with additional needs compared to the adult population. Extemporaneous formulations for children ...are generally prepared by manipulating adult formulations, but medication errors can result in suboptimal efficacy and with significant safety concerns. The aim of proposed project was to explore a 3D printing technology for the development of customized minicaplets of baclofen for the pediatric population. Based on results of 3-point bend test, polyvinyl alcohol (PVA) with sorbitol (10% w/w) were selected for preparation of baclofen loaded filaments using hot melt extrusion (HME). Effect of dimension, infill percentage and infill pattern on dose, disintegration time and release profile were investigated. Characteristic crystalline peaks of baclofen were absent in DSC thermograms and XRD pattern of filament and minicaplets. Minicaplets printed in diamond (fast) infill pattern with 100% infill showed higher disintegration time (38 mins) compared to linear, sharkfill and hexagonal pattern. 32 full factorial orthogonal design suggested that baclofen release (D50 and D85) was marginally affected by infill percentage but significantly affected by caplet dimension (p < 0.05). Thus, low cost FDM 3D printing technique can be a promising alternative for preparation of dose and release customized pediatric dosage forms.
Present study deals with the adsorption of phenol on carbon rich bagasse fly ash (BFA) and activated carbon-commercial grade (ACC) and laboratory grade (ACL). BFA is a solid waste obtained from the ...particulate collection equipment attached to the flue gas line of the bagasse-fired boilers of cane sugar mills. Batch studies were performed to evaluate the influences of various experimental parameters like initial pH (pH
0), contact time, adsorbent dose and initial concentration (
C
0) on the removal of phenol.
C
0 varied from 75 to 300
mg/l for the adsorption isotherm studies and the effect of temperature on adsorption. Optimum conditions for phenol removal were found to be pH
0
≈
6.5, adsorbent dose ≈10
g/l of solution and equilibrium time ≈5
h. Adsorption of phenol followed pseudo-second order kinetics with the initial sorption rate for adsorption on ACL being the highest followed by those on BFA and ACC. The effective diffusion coefficient of phenol is of the order of 10
−10
m
2/s. Equilibrium isotherms for the adsorption of phenol on BFA, ACC and ACL were analysed by Freundlich, Langmuir, Temkin, Redlich–Peterson, Radke–Prausnitz and Toth isotherm models using non-linear regression technique. Redlich–Peterson isotherm was found to best represent the data for phenol adsorption on all the adsorbents. The change in entropy (Δ
S°) and heat of adsorption (Δ
H°) for phenol adsorption on BFA were estimated as 1.8
MJ/kg
K and 0.5
MJ/kg, respectively. The high negative value of change in Gibbs free energy (Δ
G°) indicates the feasible and spontaneous adsorption of phenol on BFA. The values of isosteric heat of adsorption varied with the surface loading of phenol.
Key points
Pairing motor cortex stimulation and spinal cord epidural stimulation produced large augmentation in motor cortex evoked potentials if they were timed to converge in the spinal cord.
The ...modulation of cortical evoked potentials by spinal cord stimulation was largest when the spinal electrodes were placed over the dorsal root entry zone.
Repeated pairing of motor cortex and spinal cord stimulation caused lasting increases in evoked potentials from both sites, but only if the time between the stimuli was optimal.
Both immediate and lasting effects of paired stimulation are likely mediated by convergence of descending motor circuits and large diameter afferents onto common interneurons in the cervical spinal cord.
Convergent activity in neural circuits can generate changes at their intersection. The rules of paired electrical stimulation are best understood for protocols that stimulate input circuits and their targets. We took a different approach by targeting the interaction of descending motor pathways and large diameter afferents in the spinal cord. We hypothesized that pairing stimulation of motor cortex and cervical spinal cord would strengthen motor responses through their convergence. We placed epidural electrodes over motor cortex and the dorsal cervical spinal cord in rats; motor evoked potentials (MEPs) were measured from biceps. MEPs evoked from motor cortex were robustly augmented with spinal epidural stimulation delivered at an intensity below the threshold for provoking an MEP. Augmentation was critically dependent on the timing and position of spinal stimulation. When the spinal stimulation was timed to coincide with the descending volley from motor cortex stimulation, MEPs were more than doubled. We then tested the effect of repeated pairing of motor cortex and spinal stimulation. Repetitive pairing caused strong augmentation of cortical MEPs and spinal excitability that lasted up to an hour after just 5 min of pairing. Additional physiology experiments support the hypothesis that paired stimulation is mediated by convergence of descending motor circuits and large diameter afferents in the spinal cord. The large effect size of this protocol and the conservation of the circuits being manipulated between rats and humans makes it worth pursuing for recovery of sensorimotor function after injury to the central nervous system.
Key points
Pairing motor cortex stimulation and spinal cord epidural stimulation produced large augmentation in motor cortex evoked potentials if they were timed to converge in the spinal cord.
The modulation of cortical evoked potentials by spinal cord stimulation was largest when the spinal electrodes were placed over the dorsal root entry zone.
Repeated pairing of motor cortex and spinal cord stimulation caused lasting increases in evoked potentials from both sites, but only if the time between the stimuli was optimal.
Both immediate and lasting effects of paired stimulation are likely mediated by convergence of descending motor circuits and large diameter afferents onto common interneurons in the cervical spinal cord.
Treatment related lymphopenia is a known toxicity for glioblastoma (GBM) patients and several single-institution studies have linked lymphopenia with poor survival outcomes. We performed a systematic ...review and pooled analysis to evaluate the association between lymphopenia and overall survival (OS) for GBM patients undergoing chemotherapy and radiation therapy (RT).
Following PRISMA guidelines, a systematic literature review of the MEDLINE database and abstracts from ASTRO, ASCO, and SNO annual meetings was conducted. A pooled analysis was performed using inverse variance-weighted random effects to generate a pooled estimate of the hazard ratio of association between lymphopenia and OS.
Ten of 104 identified studies met inclusion criteria, representing 1,718 patients. The lymphopenia cutoff value varied (400-1100 cells/uL) and as well as the timing of its onset. Studies were grouped as time-point (i.e., lymphopenia at approximately 2-months post-RT) or time-range (any lymphopenia occurrence from treatment-start to approximately 2-months post-RT. The mean overall pooled incidence of lymphopenia for all studies was 31.8%, and 11.8% vs. 39.9% for time-point vs. time-range studies, respectively. Lymphopenia was associated with increased risk of death, with a pooled HR of 1.78 (95% CI 1.46-2.17, P < 0.00001) for the time-point studies, and a pooled HR of 1.38 (95% CI 1.24-1.55, P < 0.00001) for the time-point studies. There was no significant heterogeneity between studies.
These results strengthen observations from previous individual single-institution studies and better defines the magnitude of the association between lymphopenia with OS in GBM patients, highlighting lymphopenia as a poor prognostic factor.
Large-amplitude ion acoustic solitons (IASs) in an ultra-relativistic degenerate quantum plasma consisting of non-degenerate warm light nuclei, stationary heavy nuclei and relativistically degenerate ...electrons are investigated. The Sagdeev’s pseudo-potential approach is adopted to obtain the energy integral equation for the study large-amplitude IASs. The Mach number domain
M
l
≤
M
≤
M
h
is determined numerically in term of various parameters. Our numerical investigation shows that only compressive solitary waves can propagate in present plasma systems. The effect of different plasma parameters, such as the number density (
μ
e
), degenerate electron density (
k
), relativistic factor (
γ
), temperature ratio (
σ
) and Mach number (
M
), on the characteristic properties of solitary waves are reported. The corresponding phase trajectory is also drawn for the existing domain. The present theoretical study recovers the results from a previously published article (Sultana and Schlickeiser, Phys. Plasmas 25: 022110, 2018) for a cold multi-ion quantum plasma. Our result may be helpful to understand the basic characteristic of nonlinear solitary waves propagating in a quantum plasma, in which the non-degenerate warm light nuclei, stationary heavy ions and relativistic degenerate electrons are present. Plasmas with the given composition are found in astrophysical object such as white dwarfs, neutrons stars, etc.
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