Experimental Model For Study Research Articles

Impact of predictive, preventive and precision medicine strategies in epilepsy.

Over the last decade, advances in genetics, neuroimaging and EEG have enabled the aetiology of epilepsy to be identified earlier in the disease course than ever before. At the same time, progress in the study of experimental models of epilepsy has provided a better understanding of the mechanisms underlying the condition and has enabled the identification of therapies that target specific aetiologies. We are now witnessing the impact of these advances in our daily clinical practice. Thus, now is the time for a paradigm shift in epilepsy treatment from a reactive attitude, treating patients after the onset of epilepsy and the initiation of seizures, to a proactive attitude that is more broadly integrated into a 'P4 medicine' approach. This P4 approach, which is personalized, predictive, preventive and participatory, puts patients at the centre of their own care and, ultimately, aims to prevent the onset of epilepsy. This aim will be achieved by adapting epilepsy treatments not only to a given syndrome but also to a given patient and moving from the usual anti-seizure treatments to personalized treatments designed to target specific aetiologies. In this Review, we present the current state of this ongoing revolution, emphasizing the impact on clinical practice.

A comprehensive experimental and kinetic modeling study of 1- and 2-pentene

Abstract 1- and 2-pentene are components in gasoline and are also used as representative alkene components in gasoline surrogate fuels. Most of the available ignition delay time data in the literature for these fuels are limited to low pressures, high temperatures and highly diluted conditions, which limits the kinetic model development and validation potential of these fuels. Therefore, ignition delay time measurements under engine-like conditions are needed to provide target data to understand their low-temperature fuel chemistry and extend their chemical kinetic validation to lower temperatures and higher pressures. In this study, both a high-pressure shock tube and a rapid compression machine have been employed to measure ignition delay times of 1- and 2-pentene over a wide temperature range (600–1300 K) at equivalence ratios of 0.5, 1.0 and 2.0 in ‘air’, and at pressures of 15 and 30 atm. At high-temperatures (> 900 K), the experimental ignition delay times show that the fuel reactivities of 1- and 2-pentene are very similar at all equivalence ratios and pressures. However, at low temperatures, 1-pentene shows negative temperature coefficient behavior and a higher fuel reactivity compared to 2-pentene. Moreover, carbon monoxide time-histories for both 1- and 2-pentene were measured in a high-pressure shock tube for a stoichiometric mixture at 10 atm and at high temperatures. Furthermore, species versus temperature profiles were measured in a jet-stirred reactor at φ = 1.0 and 1 atm over a temperature range of 700–1100 K. All of these experimental data have been used to validate the current chemistry mechanism. Starting from a published pentane mechanism, modifications have been made to the 1- and 2-pentene sub-mechanisms resulting in overall good predictions. Moreover, flux and sensitivity analyses were performed to highlight the important reactions involved in the oxidation process.

Biomass to Syngas: Modified Stoichiometric Thermodynamic Models for Downdraft Biomass Gasification

To help meet the global demand for energy and reduce the use of fossil fuels, alternatives such as the production of syngas from renewable biomass can be considered. This conversion of biomass to syngas is possible through a thermochemical gasification process. To design such gasification systems, model equations can be formulated and solved to predict the quantity and quality of the syngas produced with different operating conditions (temperature, the flow rate of an oxidizing agent, etc.) and with different types of biomass (wood, grass, seeds, food waste, etc.). For the comparison of multiple different types of biomass and optimization to find optimal conditions, simpler models are preferred which can be solved very quickly using modern desktop computers. In this study, a number of different stoichiometric thermodynamic models are compared to determine which are the most appropriate. To correct some of the errors associated with thermodynamic models, correction factors are utilized to modify the equilibrium constants of the methanation and water gas shift reactions, which allows them to better predict the real output composition of the gasification reactors. A number of different models can be obtained using different correction factors, model parameters, and assumptions, and these models are compared and validated against experimental data and modelling studies from the literature.

Operational Experience of Gabion Shore Protection Structures on Mountain Rivers and Some Suggestions for their Improvement

The paper presents the accumulated experience in the construction and operation of gabions. The results of field surveys of gabions, their advantages and disadvantages, which must be taken into account in environmental practice, are presented. Innovative developments of sloping fasteners made of semi-cylindrical gabions and their construction technologies are presented. Variants of flexible retaining walls of semi-cylindrical gabions are proposed, with lower specific pressures on the soil of the base and enhanced bearing capacity on the action of bending moments. Experimental studies of prismatic and cylindrical gabion models have been carried out for a comparative assessment of their work.

Zinc Oxide Nanoparticles Induce an Adverse Effect on Blood Glucose Levels Depending On the Dose and Route of Administration in Healthy and Diabetic Rats.

Different studies in experimental diabetes models suggest that zinc oxide nanoparticles (ZnONPs) are useful as antidiabetic agents. However, this evidence was performed and measured in long-term treatments and with repeated doses of ZnONPs. This work aimed to evaluate the ZnONPs acute effects on glycemia during the next six h after an oral or intraperitoneal administration of the treatment in healthy and diabetic rats. In this study, the streptozotocin-nicotinamide intraperitoneal administration in male Wistar rats were used as a diabetes model. 10 mg/kg ZnONPs did not modify the baseline glucose in any group. Nevertheless, the ZnONPs short-term administration (100 mg/kg) induced a hyperglycemic response in a dose and route-dependent administration in healthy (130 ± 2 and 165 ± 10 mg/dL with oral and intraperitoneal, respectively) and diabetic rats (155 ± 2 and 240 ± 20 mg/dL with oral, and intraperitoneal, respectively). The diabetic rats were 1.5 fold more sensitive to ZnONPs effect by the intraperitoneal route. In conclusion, this study provides new information about the acute response of ZnONPs on fasting glycemia in diabetic and healthy rat models; these data are essential for possible future clinical approaches.

Determination and Correlation of Electrolytes and Trace Elements from Vitreous Humour and Synovial Fluid by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) for Estimation of Post-Mortem Interval (PMI): Experimental Study in an Animal Model

The estimation of post-mortem interval (PMI) procedures seem to subjectivity in assessment and lesssensitivity and specificity. Biochemical determination of trace elements from closed-system samples,such as vitreous humour (VH) and synovial fluid (SF) is an alternative laboratory investigation for PMIestimation. The inductively coupled plasma-mass spectrometry (ICP-MS) provides more rapid, precise andsensitive analysis of elements samples. However, determination of electrolytes and trace elements in VHand SF by ICP-MS, and application for PMI has not been intensively investigated. In this study, VH andSF from twenty adult domesticated pig carcasses were collected at 1, 3, 6, 12, 24, 36, and 48-hour afterdeath. Samples were analysed for total protein concentration, Ca, Cu, Fe, K and, Na using ICP-MS. Theresults showed that the protein concentration in VH was significantly increased in time dependent manner,but not for SF. The level of K and Fe in both VH and SF increased in time dependent manner, with a goodcorrelation between both sample sources. The calcium concentration of both VH and SF increased in timedependent manner, but there was no correlation between both sample sources. Sodium was significantlyreduced at 36-48 h, with a correlation between both sample sources. However, the copper level in VH wasincreased at 36-48 h but reduced in SF. In conclusion, this study showed for the first time that multiple traceelements and electrolytes could be detected, using the ICP-MS, in both of VH and SF simultaneously andadditionally its correlation.

Bone-conduction hyperacusis induced by superior canal dehiscence in human: the underlying mechanism

Our ability to hear through bone conduction (BC) has long been recognized, but the underlying mechanism is poorly understood. Why certain perturbations affect BC hearing is also unclear. An example is BC hyperacusis (hypersensitive BC hearing)—an unnerving symptom experienced by patients with superior canal dehiscence (SCD). We measured BC-evoked sound pressures in scala vestibuli (PSV) and scala tympani (PST) at the basal cochlea in cadaveric human ears, and estimated hearing by the cochlear input drive (PDIFF = PSV – PST) before and after creating an SCD. Consistent with clinical audiograms, SCD increased BC-driven PDIFF below 1 kHz. However, SCD affected the individual scalae pressures in unexpected ways: SCD increased PSV below 1 kHz, but had little effect on PST. These new findings are inconsistent with the inner-ear compression mechanism that some have used to explain BC hyperacusis. We developed a computational BC model based on the inner-ear fluid-inertia mechanism, and the simulated effects of SCD were similar to the experimental findings. This experimental-modeling study suggests that (1) inner-ear fluid inertia is an important mechanism for BC hearing, and (2) SCD facilitates the flow of sound volume velocity through the cochlear partition at low frequencies, resulting in BC hyperacusis.

EARTHQUAKE PROTECTION METHODS AND INSULATION OF EXISTING HOUSES WITH LOCAL MATERIALS

The article presents the results of experimental studies of models of houses with load-bearing walls made of local materials and methods of strengthening based on design solutions of houses, as well as recommendations.

A combined theoretical and experimental study of wear model of brush seal

In this paper, a differential equation for wear volume of brush seal has been established and the theoretical model of wear volume has been obtained. Wear volume of a brush seal was a function of interference, pressure drop, rotating speed, gas temperature, inner diameter of brush seal, diameter of a bristle, lay angle of the bristle, and thickness of the bristle pack. Besides, abrasive resistance and mechanical property of bristle and coating materials could also influence significantly. Testing has been conducted to determine the correction factor in the model and verify the model, and the theoretical results were in good agreement with the experimental results.

Experimental and kinetic modeling study of tetralin: A naphtheno-aromatic fuel for gasoline, jet and diesel surrogates

Distillate fuels contain significant proportions of naphtheno-aromatic components and tetralin is a suitable surrogate component to represent this molecular moiety. The presence of aromatic and naphthyl rings makes kinetic modeling of tetralin very challenging. Primary radicals formed during the oxidation of tetralin can be aryl, benzylic or paraffinic in nature. Using available information on reaction paths and rate constants of naphthenes and alkyl-aromatics, a kinetic model of tetralin has been developed in the current study with emphasis on low-temperature chemistry and high-pressure conditions. Due to the lack of high-level quantum chemical calculations on reaction pathways of tetralin, analogous rates from ab-initio studies on benzylic and paraffinic radicals have been adopted here. Some modifications to the reaction rate rules are incorporated to account for the unique characteristics of tetralin's molecular structure. Important reaction channels have been identified using reaction path and brute force sensitivity analyses. In order to investigate the model performance at low temperatures, new experiments are carried out in a rapid compression machine on blends of tetralin and 3-methylpentane. Blending of low-reactivity tetralin with a high-reactivity alkane allowed the investigation of tetralin ignition at very low temperatures (665 – 856 K). The kinetic model developed in the current study is found to predict the current experiments and literature data adequately. The new model will aid in high-fidelity surrogate predictions at engine-relevant conditions.

PET in the diagnostic management of infectious/inflammatory pulmonary pathologies: a revisit in the era of COVID-19.

PET in the diagnostic management of infectious/inflammatory pulmonary pathologies: a revisit in the era of COVID-19.

Experimental and Kinetic Modeling Studies of Methanol Transformation to Hydrocarbons Using Zeolite-Based Catalysts: A Review

As the need for petroleum products is increasing, it has led to increased crude oil prices. For an alternative approach, much research has been done in the field of catalytic conversion of methanol...

Does the Inion OTPSTM absorbable plating system induce higher foreign-body reaction than titanium implants? An experimental randomized comparative study in rabbits

Hardware removal after complete fracture healing is a laborious and traumatic procedure that bears the risks of refracture, infection, and soft tissue damage. Absorbable materials for fracture fixation have the advantage of eliminating the need for removal; however, they may stimulate a considerable inflammatory response. For that reason, we compared in a prospective randomized experimental animal model study the incidence of foreign-body reactions between Inion OTPSTM absorbable plate implants, consisting of carbon trimethylene, L-polylactic acid, and D, L-polylactic acid, and conventional titanium plates. Seventy rabbits were equally divided into two groups. Titanium (Group A) or absorbable (Group B) plates and screws were implanted in the femoral shaft of the rabbits. Wound reaction and laboratory tests including white blood cell count (WBC), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) values were measured and compared at different time points. Radiographs and histological analysis of tissue samples from all animals were also used to identify potential foreign-body reactions. WBC showed normal values in both groups. In Group A, ESR levels were higher at all time points but CRP values were normalized at 3 weeks postoperatively. In Group B, ESR and CRP levels reached a peak at 3 weeks and were above normal values throughout the whole experiment (p < 0.001). Radiologic examination revealed periosteal thickening and surrounding sclerosis in 23 out of 35 animals of Group B (66%). All Group A animals had normal radiographic findings. Histopathology showed a typical non-specific foreign-body reaction in all animals in Group B (100%) but none in Group A. However, only four of them (11.8%) developed non-infected wound complications and showed significantly elevated CRP and ESR values (p = 0.054). Although Inion OTPSTM Biodegradable Plating System stimulates a foreign-body reaction, only a small but not negligible percentage of almost 12% may lead to wound problems. However, this difference compared to titanium plates was of borderline not statistically significant. Future studies should focus on the development of absorbable implants with improved biocompatibility aiming to further decrease the potential of foreign-body reaction and eliminate the need for additional reoperative procedures.

Bioprosthetic aortic valve diameter and thickness are directly related to leaflet fluttering: Results from a combined experimental and computational modeling study

ObjectiveBioprosthetic heart valves (BHVs) are commonly used in surgical and percutaneous valve replacement. The durability of percutaneous valve replacement is unknown, but surgical valves have been shown to require reintervention after 10 to 15 years. Further, smaller-diameter surgical BHVs generally experience higher rates of prosthesis–patient mismatch, which leads to higher rates of failure. Bioprosthetic aortic valves can flutter in systole, and fluttering is associated with fatigue and failure in flexible structures. The determinants of flutter in BHVs have not been well characterized, despite their potential to influence durability. MethodsWe use an experimental pulse duplicator and a computational fluid-structure interaction model of this system to study the role of device geometry on BHV dynamics. The experimental system mimics physiological conditions, and the computational model enables precise control of leaflet biomechanics and flow conditions to isolate the effects of variations in BHV geometry on leaflet dynamics. ResultsBoth experimental and computational models demonstrate that smaller-diameter BHVs yield markedly higher leaflet fluttering frequencies across a range of conditions. The computational model also predicts that fluttering frequency is directly related to leaflet thickness. A scaling model is introduced that rationalizes these findings. ConclusionsWe systematically characterize the influence of BHV diameter and leaflet thickness on fluttering dynamics. Although this study does not determine how flutter influences device durability, increased flutter in smaller-diameter BHVs may explain how prosthesis–patient mismatch could induce BHV leaflet fatigue and failure. Ultimately, understanding the effects of device geometry on leaflet kinematics may lead to more durable valve replacements.

Effect of vascularized periosteum on revitalization of massive bone isografts: An experimental study in a rabbit model.

In the last years, limb salvage has become the gold standard treatment over amputation. Today, 90% of extremity osteogenic sarcomas can be treated with limb salvage surgery. However, these reconstructions are not exempt from complications. Massive allografts have been associated to high risk of nonunion (12-57%), fracture (7-30%) and infection (5-21%). Association of vascularized periosteum flap to a massive bone allograft (MBA) has shown to halve the average time of allograft union in clinical series, even compared to vascularized fibular flap. Creeping substitution process has been reported in massive allograft when periosteum flap was associated. However, we have little data about whether it results into allograft revitalization. We hypothesize that the association of a periosteum flap to a bone isograft promotes isograft revitalization, defined as the colonization of the devitalized bone by new-form vessels and viable osteocytes, turning it vital. Forty-four New Zealand white male rabbits underwent a 10 mm segmental radial bone defect. In 24 rabbits the bone excision included the periosteum (controls); in 20 rabbits (periosteum group) bone excision was performed carefully detaching periosteum in order to preserve it. Cryopreserved bone isograft from another rabbit was trimmed and placed to the defect gap and was fixed with a retrograde intramedullar 0.6 mm Kirschner wire. Rabbits were randomized and distributed in 3 subgroups depending on the follow-up (control group: 5 rabbits in 5-week follow up group, 8 rabbits in 10-week follow-up group, 7 rabbits in 20-week follow-up group; periosteum group: 5 rabbits in 5-week follow up group, 7 rabbits in 10-week follow-up group, 7 rabbits in 20-week follow-up group). Fluoroscopic images of rabbit forelimb were taken after sacrifice to address union. Each specimen was blindly evaluated in optical microscope (magnification, ×4) after hematoxylin and eosin staining to qualitative record: presence of new vessels and osteocytes in bone graft lacunae (yes/no) to address revitalization, presence of callus (yes/no) and woven bone and cartilage tissue area (mm2 ) to address remodeling (osteoclast resorption of old bone and substitution by osteoblastic new bone formation). No isograft revitalization occurred in any group, but it was observed bone graft resorption and substitution by new-formed bone in periosteum group. This phenomenon was accelerated in 5-week periosteum group (control group: 49.5 ± 9.6 mm2 vs. periosteum group: 34.9 ± 10.4 mm2 ; p = .07). Remodeled lamellar bone was observed in both 20-week groups (control group: 6.1 ± 6.3 mm2 vs. periosteum group: 5.8 ± 3.0 mm2 , p = .67). Periosteum group showed complete integration and graft substitution, whereas devitalized osteons were still observed in 20-week controls. All periosteum group samples showed radiographic union through a bone callus, whereas controls showed nonunion in eight specimens (Union rate: control group 60% vs. periosteum group 100%, p = .003). Association of vascularized periosteum to a massive bone isograft has shown to accelerate bone graft substitution into a newly formed bone, thus, no bone graft revitalization occurs.

Experimental and kinetic modeling study of oxidation of acetonitrile

Oxidation of acetonitrile has been studied in a flow reactor in the absence and presence of nitric oxide. The experiments were conducted at atmospheric pressure in the temperature range 1150–1450 K, varying the excess air ratio from slightly fuel-lean to very lean. Oxidation of CH3CN was slow below 1300 K. Nitric oxide, hydrogen cyanide and nitrous oxide were detected as important products. A detailed chemical kinetic model for oxidation of acetonitrile was developed, based on a critical evaluation of data from literature. The rate coefficients for the reactions of CH3CN and CH2CN with O2 were calculated from ab initio theory. Modeling predictions were in satisfactory agreement with experiments. Calculations were sensitive to thermal dissociation of CH3CN and to the branching fraction for CH3CN + OH to CH2CN + H2O and HOCN + CH3, respectively. More work is desirable for these steps, as well as for reactions of CH2CN and HCCN.

Ammonia–methane interaction in jet-stirred and flow reactors: An experimental and kinetic modeling study

The influence of the addition of ammonia on the oxidation of methane was investigated both experimentally and numerically. Experiments were carried out at atmospheric pressure, using a fused silica jet-stirred reactor, and a recrystallized alumina tubular reactor designed on purpose to reach temperatures as high as ∼2000 K. A temperature range of 600–1200 K was investigated in the jet-stirred reactor at a residence time of 1.5 s, while experiments in the flow reactor were carried out between 1200 and 2000 K, for a fixed residence time of about 25 ms in the reactive zone. A methane/ammonia mixture, diluted in helium, was used in both reactors with equivalence ratios varied between 0.5 and 2 in the first reactor, while stoichiometric conditions were investigated in the second one. The measurements indicate that CH4 reactivity was promoted by NH3 addition below 1200 K, but not so much influenced above. These results were interpreted and explained using a comprehensive kinetic model, previously validated over a wider range of operating conditions. The mechanism allowed to shed light on the underlying causes of the anticipated methane reactivity at low temperature, and of the major role played by NOx in it. This effect was shown to become less significant at higher temperatures, where the reactivity is mainly governed by H-abstractions on both fuels.

The effects of intravenous and local tranexamic acid on bone healing: An experimental study in the rat tibia fracture model

BackgroundTranexamic acid (TXA) is an antifibrinolytic agent. It has long been used to reduce the need for perioperative blood loss in various surgeries. Few studies have investigated the effects of local and intravenous administration of TXA on fracture healing. Thus, we aimed to evaluate if TXA influences hematoma volume and fracture healing in the rat tibia fracture model. Materials and methodsA tibia fracture with intramedullary Kirschner wire fixation was created in all animals. Rats were randomly divided into three groups as local TXA, intravenous TXA, and control. A dose of 50 mg/kg local and intravenous TXA was administered to the study groups. Hematoma volume was measured on the first and third days of the study. The animals were sacrificed on the 14th and 21st days for radiological and histopathological examinations. ResultsThere was no significant difference between the groups in terms of hematoma volume measured on Day 1 and the mean decrease of hematoma volume from Day 1 to Day 3 (p = 0.158 and p = 0.239, respectively). The total radiological scores of Day 14 and Day 21 were similar in all groups (p > 0.05 for all). There was also no significant difference between the histological staging of the fracture repair on Day 14 and Day 21 for all groups (p > 0.05 for all). ConclusionOur findings suggest that TXA's local and intravenous application makes no significant difference in fracture healing.

An experimental and kinetic modeling study of a four-component surrogate fuel for RP-3 kerosene

Detailed high-fidelity kinetic models of fuels are of great significance by providing guidance for the improvement of the combustion performance in engines and promising the reduction of design cycle of new concept combustors. However, the kinetic modeling works on Chinese RP-3 kerosene, the most widely used civil aviation fuel in China, are meager to date. In this study, a kinetic model, including a surrogate fuel and its combustion kinetic mechanism, were developed to describe the combustion of RP-3. Firstly, a surrogate comprised of components n-dodecane, 2,2,4,6,6-pentamethylheptane (PMH), n-butylcyclohexane and n-butylbenzene (22.82/31.30/19.19/26.69 mol%) was proposed based on the combustion property target matching method. These components are all within the typical molecular size (C10-C14) of jet fuels and thereby can potentially improve the ability of the surrogate in emulating the properties that depend on molecular size. Experiments were then carried out in a heated rapid compression machine and a heated shock tube to evaluate the performance of the surrogate in reproducing the combustion behavior of the target fuel over wide conditions. It is found that the surrogate can reproduce the autoignition characteristics of RP-3 very well. A chemical kinetic mechanism was developed to describe the oxidation of this surrogate. This mechanism was assembled using a published n-butylbenzene sub-mechanism and our previous sub-mechanisms for the other pure components, and was assessed against the present experimental data. The results showed that the simulations agreed well with the experimental data under the investigated conditions, demonstrating that the composition of the surrogate and its mechanism are appropriate to describe the combustion of RP-3. The first-stage ignition negative temperature coefficient behavior and the evolution of key radicals were investigated using the kinetic model.

An experimental and kinetic modeling study on nitric oxide formation in premixed C3 alcohols flames

This study provides new quantitative NO concentrations measurements in n-propanol + air and i-propanol + air flames together with a new combustion kinetic model. The heat flux method was employed to stabilize propyl alcohols flames and the initial gas conditions were set to 323 K, 1 atm, and Φ=0.7–1.4. Saturated laser-induced fluorescence was employed to measure NO concentration in the post-combustion region. The presented and literature models, namely the POLIMI and Bohon et al. (2018) kinetic mechanisms, were assessed against new experimental data. Experimental results showed a higher NO formation in the thermal zone for n-propanol flames, whereas i-propanol flames indicate a higher amount of NO formed at fuel-rich conditions. Overall among the tested models, the present mechanism exhibited the best agreement in emulating NO experimental profiles; conversely, numerical simulations from the POLIMI model showed significant inconsistencies at fuel-rich conditions and the Bohon et al. (2018) model was unable to reproduce the measured data, notably underpredicting experimental values at all investigated conditions. However, the present model manifested some uncertainties in reproducing NO formation in the prompt region; therefore, in connection with this important aspect, the new experimental data obtained in this work will provide a valid support to further develop more reliable kinetic models.