Low Contact Time Research Articles

One-pot glycerol oxidehydration to acrylic acid on multifunctional catalysts: Focus on the influence of the reaction parameters in respect to the catalytic performance

We report on a study of the key reaction parameters in glycerol oxidehydration into acrylic acid over W–V–Nb mixed oxides with a hexagonal tungsten bronze structure. This investigation demonstrated that the optimal control of the two consecutive steps of acid-catalysed glycerol dehydration into acrolein and aldehyde oxidation into acrylic acid, and of the parallel reaction of acrolein transformation into by-products (ketals and oligomers), was achieved in the presence of a defined glycerol-to-oxygen inlet ratio. Indeed, oxygen played the fundamental role of accelerating the oxidation of the intermediately formed acrolein into acrylic acid, by allowing a greater concentration of the oxidizing V5+ sites. In fact, an unprecedented higher yield to acrylic acid and acrolein compared to W–V bronzes was registered (maximum acrylic acid yield 50.5%) together with an increase of more than one order of magnitude in productivity, because of both the greater concentration of glycerol used in the inlet feed and the lower contact time needed. Further experiments were carried out by reacting acrolein and methanol in oxidative conditions, the latter as a model molecule for the determination of surface acid and redox properties.

Occurrence and removal of selected micropollutants in a water treatment plant

The levels of 14 micropollutants including nine pharmaceuticals, two pesticides, and three endocrine disruptors were measured in a water treatment plant (WTP) in Seoul, Korea. Among the measured micropollutants, 12 (excluding atrazine and triclocarban) were found in the influent and effluent from the WTP, at levels ranging from 2 to 482ngL−1. The removal efficiencies of the detected micropollutants in the WTP ranged from 6% to 100%. Among them diclofenac, acetaminophen, caffeine, carbamazepine, and 2,4-D were effectively removed (>80%). Metoprolol was unlikely to be removed (6%) in the WTP process. Concentrations of acetaminophen, metoprolol, ibuprofen, and naproxen were higher in winter, while levels of herbicides of 2,4-dichloro-phenoxyacetic acid (2,4-D) were higher in summer. Metoprolol was hardly removed in the water treatment process. Laboratory experiments showed that compounds with logKow>2.5 (especially bisphenol-A, 2,4-D, carbamazepine, triclocarban and 4-nonylphenol) were effectively removed by coagulation process, and adsorption effect increased in proportion with hydrophobicity of micropollutants and the turbidity of water. Sunlight photodegradation also effectively removed sulfamethoxazole, sulfamethazine, caffeine, diclofenac, ibuprofen, and acetaminophen, which are photosensitizes. Chlorination was relatively not effective for the removal of micropollutants due to the lower chlorine dosage (2mgL−1), lower contact time (1h), and already lower levels of micropollutants at the chlorination stage at WTP. Our results imply that micropollutants during coagulation stage at WTP can be removed not only by coagulation itself, but also by adsorption to clay particle especially for high turbidity water, and by sunlight photodegradation in the areas open to the atmosphere.

Removal of textile dyes from aqueous solution by conducting polymer modified clinoptilolite

In this work, clinoptilolite was modified with conducting polyaniline polymer and then the nanocomposite was used as an adsorbent for methyl orange (MO) as a model dye. Cations located in clinoptilolite structure like Na+, K+, Mg2+, Ca2+ were exchanged with anilinium cations and then the polymerization of anilinium cations in and outside of the clinoptilolite channels resulted in the formation of polyaniline/clinoptilolite nanocomposite. The resulted nanocomposite was used for the removal of MO from aqueous solution. The effect of various factors like contact time, concentration of dye as well as the amount of adsorbent on the removal efficiency of dye was investigated. The adsorption isotherms were investigated. It was found that the equilibrium adsorption data were well described by the Langmuir isotherm model. The kinetic studies indicated that the adsorption process was controlled by pseudo-second-order equation. High adsorption capacity and low contact time as well as the low cost of modified clinoptilolite proved that it is an efficient adsorbent for the removal of MO from aqueous solutions.

Inactivation of Aspergillus flavus in drinking water after treatment with UV irradiation followed by chlorination

The disinfection process for inactivating microorganisms at drinking water treatment plants is aimed for safety of drinking water for humans from a microorganism, such as bacteria, viruses, algae, fungi by using chlorination, ozonation, UV irradiation, etc. In the present study, a combination of two disinfectants, UV irradiation followed by chlorination, was evaluated for inactivating Aspergillus flavus under low contact time and low dosage of UV irradiation. The results indicated an inverse correlation between the inactivation of A. flavus by using UV irradiation only or chlorination alone. By using UV radiation, the 2 log10 control of A. flavus was achieved after 30s of irradiation, while chlorination was observed to be more effective than UV, where the 2 log was achieved at chlorine concentration of 0.5, 1, 2 and 3mg/l, in contact time of 60, 5, 1 and 1min, respectively. However, combined use (UV irradiation followed by chlorination) was more effective than using either UV or chlorination alone; 5s UV irradiation followed by chlorination produced 4 log10 reduction of A. flavus at chlorine concentrations of 2 and 3mg/l under a contact time of 15min. The results indicated that efficiency of UV irradiation improves when followed by chlorination at low concentrations.

Effects of pH, Sodium Chloride, and Curing Salt on the Infectivity of Toxoplasma gondii Tissue Cysts

Toxoplasma gondii is one of the most common zoonotic parasites in the world. The parasite causes no or mild symptoms in immunocompetent humans. However, a high potential hazard exists for seronegative pregnant women and immunocompromised patients. The consumption of meat containing tissue cysts or oocyst-contaminated vegetables and fruits or the handling of cat feces poses a high risk of infection with T. gondii. It is known that raw minced meat, raw fresh sausages, and locally produced raw meat products are possible causes of T. gondii infection. The infectivity of T. gondii tissue cysts in meat products depends, among other factors, on the pH and the salt concentration. Therefore, the impact of these two factors on the tissue cysts was examined. For this purpose, dissected musculature and brain from experimentally infected mice (donor mice) were placed in a cell culture medium (RPMI 1640). The medium was adjusted to different pH values (pH 5, 6, and 7) with lactic acid and to different salt concentrations (2.0, 2.5, and 3.0%) with sodium chloride (NaCl) or nitrite-enriched curing salt (NCS) for the various tests. After storage at 4°C for different time periods, the materials were fed to bioassay mice. Later, the brains were examined for presence of T. gondii to assess the infectivity. The data show that T. gondii tissue cysts have a high pH tolerance. Cysts were infectious in the muscle for up to 26 days (pH 5). In contrast to their tolerance to pH, cysts were very sensitive to salt. Muscle cysts survived at an NaCl concentration of up to 2.0% only, and for no longer than 8 days. At NaCl concentrations of 2.5 and 3.0%, the cysts lost their infectivity after 1 day. When NCS instead of NaCl was used under the same conditions, T. gondii muscle cysts retained infectivity for only 4 days at 2.0%. Consequently, NCS (NaCl plus 0.5% nitrite) has a stronger effect on T. gondii cysts than does common table salt. Sausages produced with low NaCl concentration and short contact times pose a potential risk for susceptible individuals.

Pilot study of the removal of individual trihalomethanes (THMs) from chlorinated drinking water by GAC adsorption - Galatsi water treatment plant, Athens, Greece

<p>The objective of this pilot study was to evaluate the performance of Powdered Activated Carbon (PAC) for the removal of individual trihalomethanes (THMs) from chlorinated drinking water, Athens, Greece. The pilot treatment facility was located at the Water Treatment Plant of EYDAP (Athens Water Supply and Sewerage Company) in Galatsi, Athens, and consisted of two mixing tanks operating as open batch reactors, which were fed with chlorinated water from the overflow of the sedimentation tanks. Experimental cycles were performed, with different PAC doses ranging from 5 to 50 mg L-1 and with contact times 30 and 60 min for each cycle. Water samples taken at the start of each cycle and after contact with PAC, were analysed for individual THMs and Dissolved Organic Carbon (DOC). Bromide, free residual chlorine, pH and temperature were also measured. From the experimental results, it was shown that all THMs concentrations were decreased after PAC contact, the decrease being higher for higher PAC dose and higher contact time, with few exceptions. This fact probably indicates that adsorption rate plus volatilisation rate of THMs overcame formation rate, in most cases. It was also concluded that volatilisation and possible formation reactions of THMs had probably a more apparent effect to the total removal of most THMs at low PAC doses and low contact time. At higher PAC doses and higher contact time, PAC adsorption probably had an increased contribution to THMs removal, because of the larger carbon surface area and the longer contact time, resulting in higher adsorbed mass according to adsorption theory. By using isotherm results of individual THMs on activated carbon by other researchers, the theoretically adsorbed mass of THMs per g of PAC was roughly estimated and compared with the measured removed mass of THMs per g of PAC at PAC dose 50 mg L-1 and contact time 60 min for most THMs, on the assumption of equilibrium achievement. The removed mass of THMs by PAC appeared much higher than the theoretically adsorbed, especially for the most volatile members. The difference was attributed to volatilisation taking place in the open mixing tanks. In conclusion, the practical results from the application of PAC for the removal of THMs are much better than expected from single adsorption by PAC. Volatility of THMs, especially of chloroform (TCM), substitutes for weak adsorbability and gives increased removal. The influent DOC was almost constant in all experiments. The removal of DOC was generally higher for increased PAC dose and contact time. Although equilibration cannot have happened for DOC, the mass removal of DOC per g of PAC was higher by more than two orders of size than that of the smaller and in lower concentration THMs, as expected.</p>

Removal of chromium from water effluent by adsorption onto <i>Vetiveria zizanioides</i> and <i>Anabaena</i> species

Bioadsorption phenomenon is more or less like a chemical reaction and several parameters are bound to affect the process. The pH, amount of adsorbent and agitation time influence the biosorptive potentiality. Hence, the present study on adsorption of Cr(VI) by activated Vetivera roots and Blue green algae Anabaena supports that it is an effective low cost adsorbent for the removal of Cr(VI) from plating effluent. Langmuir and Freundlich adsorption isotherm correlate the equilibrium adsorption data. In batch experiments both Vetiveria and Anabaena species were found to be cost effective biosorbent for the efficient removal of Cr(VI) from the effluent and comparatively Anabaena species was found to adsorb maximum Cr(VI) (88.86%) at a low contact time of 60 min. The data obtained from the experiments and modeling would prove useful in designing and fabricating an efficient treatment plant for Cr(VI) rich effluent.

INHIBITORY EFFECT OF BIOCIDES ON ENVIRONMENTAL S. AUREUS STRAINS

The aim of this study was to evaluate the inhibitory effect of biocides on S.aureus strains isolated in dairy environment. After a contact time of 5' all tested molecules showed total growth inhibition of bacteria; for lower contact time results were depending on strains and biocides.

INHIBITORY EFFECT OF BIOCIDES ON ENVIRONMENTAL S. AUREUS STRAINS

The aim of this study was to evaluate the inhibitory effect of biocides on S.aureus strains isolated in dairy environment. After a contact time of 5' all tested molecules showed total growth inhibition of bacteria; for lower contact time results were depending on strains and biocides.

Removal of Acid Orange 7 and Remazol Black 5 reactive dyes from aqueous solutions using a novel biosorbent

This study utilizes canola stalks (CS), an agro-residue, as a biosorbent to remove two different dyes, namely Acid Orange 7 (AO7) and Remozol Black 5 (RB5) from aqueous solutions. The effects of operational parameters on the efficiency of dye removal including pH, adsorbent mass, initial dye concentration and contact time have been investigated. For both tested dyes, the maximum absorption capacity was reached at initial pH 2.5 and 120min contact time. The results showed that the absorption of both dyes depended on the pH of milieu, temperature, dye and CS concentrations. Freundlich and Langmuir models were used to analyze the obtained experimental data. The isotherms are found to be linear over the entire concentration range for both dyes. The highest value of linear correlation coefficients for AO7 (0.9926) and RB5 (0.9882) showed that the Langmuir is the best model to fit the experimental data. Kinetic study of absorption was done applying the pseudo first-order and the pseudo second-order equations. Absorption of both dyes could be well predicted by the pseudo second-order equation. The obtained results are very promising since: (i) high levels of dye removal (>90%) were achieved with low contact times biosorbent/dye (less than 20min contact); and (ii) the whole CS can be successfully used as biosorbent of AO7 and RB5 dyes in aqueous solution without needing any chemical modifications.

Influence of different sanitizers on food contaminant bacteria: effect of exposure temperature, contact time, and product concentration

The efficiency of four Sanitizers - peracetic acid, chlorhexidine, quaternary ammonium, and organic acids - was tested in this work using different bacteria recognized as a problem to meat industry, Salmonella sp., S. aureus, E. coli and L. monocytogenes. The effects of sanitizer concentration (0.2, 0.5, 0.6, 1.0, 1.1 and 1.4%), at different temperatures (10 and 45 °C) and contact time (2, 10, 15, 18 and 25 minutes) were evaluated. Tests in an industrial plant were also carried out considering previously obtained results. In a general way, peracetic acid presented higher efficiencies using low concentration (0.2%) and contact time (2 minutes) at 10 °C. The tests performed in industrial scale showed that peracetic acid presented a good performance in concentration and contact time lower than that suggested by the suppliers. The use of chlorhexidine and quaternary ammonium led to reasonable results at the indicated conditions, and organic acids were ineffective under concentration and contact time higher than those indicated by the suppliers in relation to Staphylococcus aureus. The results, in general, show that the choice for the most adequate sanitizer depends on the microorganism contaminant, the time available for sanitizer application, and also on the process cost.

Hydrogen production through catalytic low-temperature bio-ethanol steam reforming

As a provider of our energy requirements, hydrogen seems to be one of most promising fuels, in particular when used to feed PEM fuel cells. When produced from a renewable source, it has got the potential to reduce the dependence on non-renewable fossil fuels and lower the amount of harmful emissions. Ethanol steam-reforming (ESR) reaction is an interesting option to obtain a H2- and CH4-rich stream with a low content of CO, combining the deep knowledge of the technology with the advantage of the biomass-derived feedstock. Thermodynamic analysis has indicated that the most interesting operating range to enhance the H2 production and minimize CO and coke formation requires low pressure, high temperature, and high water-to-ethanol molar ratio. On the other hand, despite its endothermic nature, ESR could be carried out at low temperature, to increase overall thermal efficiency, even if at these conditions the catalyst's deactivation, due to coking and sintering phenomena, is not negligible. The main objective of this study is to investigate on the activity, stability, and durability of bimetallic Pt–Ni and Pt–Co catalysts supported on CeO2 for low-temperature bio-ESR reaction. The catalysts have been prepared through different methods and with an optimized metal's content. They have also been characterized with various physico-chemical characterization tests, and the catalytic studies have been carried out in a lab-scale apparatus. While evaluating the effects on the catalysts' performances of preparation method, reaction temperature, space time, and water-to-ethanol molar ratio, the selected catalysts were found effective for the production of H2 by steam reforming at low temperature. In particular, the Pt/Ni/CeO2 catalyst shows a perfect agreement with equilibrium calculations yet at low contact times, although some carbon deposition occurs. Also the cobalt-based catalysts appear attractive. The relative rates of carbon growth versus gasification have been studied, and ascending water contents were used to study the effect of steam addition in the feed stream. An in-depth investigation of the reaction mechanism and the evaluation of the kinetic parameters will be crucial to complete the study of the proposed process.

Microfluidic diffusion measurements: The optimal H-cell

This article reports the optimal design and measurement conditions for microfluidic diffusion experiments. For this purpose, we conducted and experimentally validated the model-based Optimal Experimental Design (OED) of a pressure-driven H-cell microchannel for diffusion measurements in liquids. While earlier work employed low Fourier numbers (i.e., low contact times), our results show the existence of an optimal finite Fourier number for which the measurement sensitivity increases drastically. For the optimal contact times (Fo=0.30…0.39), the accuracy of diffusion measurements is improved by orders of magnitude compared to the previously used sub-optimal low Fourier region (Fo<0.01). A general design rule for optimal H-cell diffusion experiments is derived. To demonstrate the utility of the optimized microfluidic method, diffusion coefficients are measured for a variety of binary mixtures. We show that H-cell measurements designed and operated according to the identified principles lead to a fast, efficient and cheap method for high-throughput diffusion analysis.

Sujeitos com Síndrome da Dor Patelofemoral apresentam fraqueza muscular e menores cargas plantares - Relato de Caso

Introdução: A Síndrome da Dor Patelofemoral (SDPF) caracteriza-se como dor difusa na região anterior do joelho. Objetivo: Avaliar a distribuição da pressão plantar durante duas atividades funcionais, subir e descer escadas, bem como torque e trabalho dos flexores e extensores do joelho em um sujeito com e um sem SDPF. Método: Realizou-se avaliação da distribuição da pressão plantar durante duas atividades funcionais, subir e descer escadas, e avaliação isocinética dos flexores e extensores do joelho, além verificar a intensidade da dor antes e após cada atividade em um indivíduo com e um sem SDPF. Resultados: O sujeito com SDPF apresentou menor tempo de contato e menores valores para a integral pressão-tempo, bem como menor pico de torque e trabalho dos flexores e extensores do joelho. Conclusão: A SDPF levou a redução da carga no membro comprometido ao subir e descer escadas e a fraqueza dos flexores e extensores do joelho.

INVESTIGATION OF CATALYTIC CONVERSION OF FISCHER-TROPSCH WAX ON Pt/AlSBA-15 AND Pt/BETA ZEOLITE CATALYSTS

Because of the more serious problems with the environment (e.g. greenhouse effect) and the crude oil supply (e.g. import dependence) the use of fuels and lubricants produced from renewable feedstocks have come to the front nowadays. The Fischer-Tropsch wax (60–80% of the Fischer-Tropsch products) which is produced on synthesis gas from different sources (biological or waste), is a mixture of high molecular weight (C20-C60) n-paraffins, which are in solid state (high pour point) at normal conditions. The products (fuels and base oils) which can be produced from this paraffin mixture have high quality and have fewer negative effects on the environment (practically zero sulphur- and nitrogen content, low aromatic content, excellent application properties) thus theydo not demand changes in the fuel supply infrastructure and in the engine constructions. The isomerization of high molecular weight n-paraffins can be effectively carried out on bifunctional catalysts. There are only a few indications about the application of metal catalysts on mesoporous carrier in the literature. Consequently our objective was to investigate some Pt/AlSBA-15 (SBA: Santa Barbara Amorphous) catalysts which have not been investigated in detail in this reaction system yet, and compare its properties with a Pt/beta zeolite catalyst which has been recommended for this reaction earlier. The applicability and catalytic activity of Pt/AlSBA-15 and Pt/beta zeolite catalysts of 0.5% platinum content for the selective isomerization of Fischer-Tropsch wax was investigated in the present experiment. The experiments werecarried out in a high-pressure microreactor system in continuous operation and on a catalyst with steady-state activity. The main properties of the feedstock which was a mixture of paraffin produced by Fischer-Tropsch synthesis (the synthesis gas was produced from biomass) were: n-paraffin content (C18-C57): 97.4%, sulphur content: 5 mg/kg, pour point: 72 °C. In the experiment the following process parameters were applied: T=275–375 °C, P=40–80 bar, LHSV=1.0–3.0 h-1, H2/hydrocarbon ratio: 400–800 Nm3/m3. The composition of the products was determined by gas chromatography. From the catalysts with different support the best results were gained on the catalysts with AlSBA-15 support, and with increasing temperature the yield of liquid products (C5+) decreased, but until 325 °C this value was above 93% in every case. Incase of the beta zeolite high amount of cracking took place. Increasing the pressure shifted back the hydrocracking reactions(with the increasing number of moles) so it had a decreasing effect on the volume of the gas products and the lower contact time (higher liquid hour space velocity) had the same effect. In the gas products mainly branched isobutane was identified, which indicated that the cracking enacted partly after the isomerization reactions. The isoparaffin contents of the liquid products in the function of process parameters increased with increasing temperature and decreased with increasing pressure and LHSV in every case while other parameters were kept constant. Based on the isoparaffin contents of the different fractions it can be concluded that on Pt/AlSBA-15 catalyst at advantageous process parameter combinations (T=300–325 °C (C11-C20)/ 275–300 °C (C21-C30), P=40–80 bar, LHSV=1.0–2.0 h-1) the catalyst was applicable to produce C11-C20 and C21-C30 fractions with high isoparaffin content (63.5–85.6% and 34.1–58.7%) with adequate yields (29.9–36.6% and 46.2–58.8%). We experienced that the gas oil fractions having the lowest pour point were obtained in the case of high concentrations of 5-methyl isomers. The C21-C30 fraction is a high viscosity index (VI ≥125) base oil. The selectivity of the target product fractions was high, and based on these facts the selective isomerization of the Fischer-Tropsch wax can be a new application area of the Pt/AlSBA-15 catalyst.

ARSENIC REMEDIATION USING SURFACE FUNCTIONALIZED ULTRAFINE NANOPARTICLES

Ultrafine nanoparticles owing to their increased surface to volume ratio, coupled with the ability to tune their surface properties through molecular modification have made them ideal for their detection and remediation of broad range of environmental contaminants. Arsenic contamination has become a worldwide epidemic and remediation of this problem needs the development of technology with improved materials and systems with high efficiency. In the present study, we have demonstrated a simple and efficient method using surface functionalized ultrafine iron oxide nanoparticles for absolute removal of arsenic from arsenic treated water with low contact time period and low adsorbent dose. The efficiency of arsenic removal has been drastically improved by considering nanoparticles of size 10 nm and subsequent surface engineering of the nanoparticles resulting more adsorption sites being exposed to arsenic. The mechanism for adsorption was identified through electron microscopic and spectroscopic studies. The adsorption equilibrium data were well fitted to Freundlich isotherm.

Natural Rubber-Based Pressure-Sensitive Adhesives: A Review

The purpose of this review is to describe the various aspects of pressure-sensitive adhesives prepared from natural rubber. Pressure-sensitive adhesives (PSAs) adhere instantaneously to a variety of surfaces upon application of slight pressure and can be obtained using different technologies. PSAs are materials that develop tack for low pressures and short contact times. There are number of factors affecting the adhesion property of natural rubber based pressure-sensitive adhesives. In this review, factors affecting adhesion property such as tack, peel and shear are examined in light of their relevance to adhesion in addition to measurement methods of each of the three major adhesion properties. This review paper covers the work being carried out from the last 20 years in the field of natural rubber based pressure sensitive adhesives.

Changes in Running Kinematics, Kinetics, and Spring-Mass Behavior over a 24-h Run

This study investigated the changes in running mechanics and spring-mass behavior over a 24-h treadmill run (24TR). Kinematics, kinetics, and spring-mass characteristics of the running step were assessed in 10 experienced ultralong-distance runners before, every 2 h, and after a 24TR using an instrumented treadmill dynamometer. These measurements were performed at 10 km·h, and mechanical parameters were sampled at 1000 Hz for 10 consecutive steps. Contact and aerial times were determined from ground reaction force (GRF) signals and used to compute step frequency. Maximal GRF, loading rate, downward displacement of the center of mass, and leg length change during the support phase were determined and used to compute both vertical and leg stiffness. Subjects' running pattern and spring-mass behavior significantly changed over the 24TR with a 4.9% higher step frequency on average (because of a significantly 4.5% shorter contact time), a lower maximal GRF (by 4.4% on average), a 13.0% lower leg length change during contact, and an increase in both leg and vertical stiffness (+9.9% and +8.6% on average, respectively). Most of these changes were significant from the early phase of the 24TR (fourth to sixth hour of running) and could be speculated as contributing to an overall limitation of the potentially harmful consequences of such a long-duration run on subjects' musculoskeletal system. During a 24TR, the changes in running mechanics and spring-mass behavior show a clear shift toward a higher oscillating frequency and stiffness, along with lower GRF and leg length change (hence a reduced overall eccentric load) during the support phase of running.

Removal of As(III) from Aqueous Solution Using Functionalized Ultrafine Iron Oxide Nanoparticles

Arsenic toxicity has become a major concern worldwide. Remediation of this problem needs the development of technology with improved materials and systems with high efficiency. We have demonstrated a simple and efficient method for the absolute removal of As(III) from high concentration As(III) treated water with a low contact time period. The process of As(III) adsorption follows pseudo-second-order kinetic model. The mechanism for high-adsorption efficiency is attributed to fatty acid binding domain-mediated surface conjugation of ultrafine Fe2O3 nanoparticles with As(III). We have also ensured the simultaneous separation of arsenic sorbed nanoparticles by entrapping them in hydrophilic calcium alginate beads and thereby a pure arsenic free solution has been obtained.

Locomotion in Simulated and Real Microgravity: Horizontal Suspension vs. Parabolic Flight

The effect of reducing gravity on locomotion has been studied using microgravity analogues. However, there is no known literature comparing locomotion in actual microgravity (AM) to locomotion in simulated microgravity (SM). Five subjects were tested while walking at 1.34 m x s(-1) and running at 3.13 m x s(-1) on a treadmill during parabolic flight and on a microgravity simulator. The external load (EL) in AM and SM was provided by elastomer bungees at approximately 55% (low) and 90% (high) of the subjects' bodyweight (BW). Lower body joint kinematics and ground reaction forces were measured during each condition. Effect size and its 95% confidence interval were computed between gravitational conditions for each outcome variable. In AM, subjects attained approximately 15-21 degrees greater hip flexion during walking and 19-25 degrees greater hip flexion during running. Hip range of motion was greater in AM during running by approximately 12-17 degrees. Trunk motion was 4 degrees less in SM than AM during walking. Peak impact force was greater in SM than in AM during walking with a low EL (SM = 0.95 +/- 0.04 BW; AM = 0.76 +/- 0.04 BW) and contact times were greater in SM. Subtle differences exist in locomotion patterns, temporal kinematics, and peak impact ground reaction forces between AM and SM. The differences suggest possible adaptations in the motor coordination required between gravitational condition, and potential differences in adaptations that are dependent upon if training occurs in actual or simulated microgravity.