Short Contact Time Research Articles

Fast droplet bouncing induced by asymmetric spreading on concave superhydrophobic surfaces

A droplet can bounce in a short contact time after impacting on superhydrophobic surfaces (SHSs), which is of benefit to the applications like anti-icing, anti-frosting and self-cleaning. In this study, we numerically investigate the fast droplet bouncing induced by asymmetric spreading on the concave SHS with a trapezoidal cross-section and focus on the droplet morphology evolution and contact time variation. A preferential transport at the both sides of the droplet from the inclined part to the flat part will occur because of the concave structure feature. The droplet will exhibit asymmetric spreading behavior. Moreover, the effects of structure parameters and impact velocity on the droplet contact time are explored. Within this concave structure, the droplet contact time is less influenced by the impact velocity and more influenced by the structural parameters. The presence of the tangential momentum can enhance the droplet asymmetric spreading, but it is not always beneficial to the droplet contact time reduction. Therefore, there will be an optimal structure to achieve the minimum droplet contact time. A concave SHS structure with the structure width w= 1–1.2r and the inclination angle of 45° is a more desirable choice, which is expected to reduce the droplet contact time by 40~45%.

Reversible Transformation between Azo and Azonium Bond Other than Photoisomerization of Azo Bond in Main-Chain Polyazobenzenes.

Although side-chain polyazobenzenes have been extensively studied, main-chain polyazobenzenes (abbreviated MCPABs) are rarely reported due to the challenges associated with difficulty in synthetic chemistry and photoisomerization of azo bonds in MCPABs. Thus, it is highly demanded to develop new mechanisms other than photoisomerization of azo bonds in MCPABs to extend their applications. In this work, we created a new series of N-linked MCPABs via fast NaBH4-mediated reductive coupling polymerization on N-substituted bis(4-nitrophenyl)amines. The structure of MCPABs has been characterized by comprehensive solid-state NMR experiments such as CPMAS 13C NMR with long and short contact times, cross-polarization polarization-inversion (CPPI), and cross-polarization nonquaternary suppressed (CPNQS). The azo bonds in MCPABs were found to be promising for acid vapor sensing, being acidified to form azonium ion with significant color change from red to green. And the azonium of MCPABs turned from green to red when exposed to base vapor, thus suitable for base vapor sensing.

Antimicrobial Nanofiber Based Filters for High Filtration Efficiency Respirators.

Electrospinning has been used to develop and upscale polyacrylonitrile (PAN) nanofibers as effective aerosol filtration materials for their potential use in respirators. The fibers were deposited onto non-woven spunbond polypropylene (SPP) and the basis weight (grammage, g/m2) was varied to assess the resulting effect on filtration efficiency and breathing resistance of the materials. The results indicated that a basis weight in excess of 0.4 g/m2 of PAN electrospun fibers yielded a filtration efficiency over 97%, with breathing resistance values that increased proportionally with the amount of basis weight added. With the aim of retaining filter efficiency whilst lowering breathing resistance, the basis weight of 0.4 g/m2 and 0.8 g/m2 of PAN electrospun fibers were strategically split up and stacked with SPP in different configurations. The results suggested that a symmetric structure based on SPP/PAN/PAN/SPP was the optimal structure, as it reduces SPP consumption while maintaining an FFP2-type of filtration efficiency, while reducing breathing resistance, specially at high air flow rates, such as those mimicking FFP2 exhalation conditions. The incorporation of zinc oxide (ZnO) nanoparticles within the electrospun nanofibers in the form of nanocomposites, retained the high filtration characteristics of the unfilled filter, while exhibiting a strong bactericidal capacity, even after short contact times. This study demonstrates the potential of using the symmetric splitting of the PAN nanofibers layer as a somewhat more efficient configuration in the design of filters for respirators.

Heat transfer, physiological responses, and subjective perceptions during short contact time with wood or other materials

This study investigates the physiological responses and subjective perceptions of touching wood. In particular, it focuses on their respective relationships with the amount of heat transfer across the hand–material interface during contact. The study participants included 55 university students (20 females and 35 males) who gave written informed consent. The participants’ blood pressure, pulse rate, and cerebral blood hemoglobin concentrations were measured continuously for 90 s while they gently held vertical bar-shaped specimens of Japanese cypress (Chamaecyparis obtusa), Japanese oak (Quercus crispula), polyethylene, and aluminum. The specimens also included wood with a surface coating. We measured subjective warmth and comfort as well as the heat flux between the palm and the surface of the material. The wooden materials were rated as significantly warmer compared to aluminum and polyethylene, regardless of the wood species (cypress or oak) or its coating; this result corresponds with smaller heat transfers in the wooden materials. Additionally, the wooden materials were more comfortable to hold as compared to the aluminum bar. Based on the changes in blood pressure, touching Japanese cypress and uncoated Japanese oak were interpreted to induce less physiological stress. Therefore, we can conclude that wood, with lower thermal conductivity, feels warm, and it causes relatively smaller physiological changes compared to other materials with higher thermal conductivity. Thus, they may present less physiological burdens when touched.

Mechanism of pre-ozonation in control of protein fouling of ultrafiltration membranes: Synergistic effect between ozone oxidation and aeration

Pre-ozonation is often used before ultrafiltration (UF) to control membrane fouling, usually by supplying ozone into water or wastewater via aeration. However, the role of aeration in pre-ozonation for mitigation of membrane fouling has not been well elucidated. Hence, in this study, bovine serum albumin (BSA) was used as a protein-type foulant in experiments on the outcomes and underlying mechanisms of pre-ozonation. The change in the membrane fouling behavior, the transformation of BSA, and the fouling-layer properties were investigated after pre-ozonation with and without aeration. The results showed that the membrane fouling notably declined after pre-ozonation, which mainly attributed to the synergistic effect between ozone oxidation and aeration. Ozone oxidation unfolded the BSA molecules and exposed their hydrophobic groups, and these unfolded BSA aggregated and adhered to the surface of the microbubbles produced by aeration. This induced BSA foaming and aggregation in the ozonated suspension. With pre-ozonation for a short contact time of 5 min, small BSA aggregates in water were retained on the UF membrane surface to form a highly porous deposition layer with a low filtration resistance. With pre-ozonation for a contact time of 10 min or longer, BSA foaming led to the formation of large aggregates that were efficiently removed from water in the ozone reactor, which greatly reduced the foulant loading of the water and its subsequent membrane fouling rate. In contrast, when quantitative and quiescent ozonation was performed without aeration, ozone oxidation alone worsened the membrane fouling propensity of the BSA solution.

Development of a simulated lung fluid leaching method to assess the release of potentially toxic elements from volcanic ash

Freshly erupted volcanic ash contains a range of soluble elements, some of which can generate harmful effects in living cells and are considered potentially toxic elements (PTEs). This work investigates the leaching dynamics of ash-associated PTEs in order to optimize a method for volcanic ash respiratory hazard assessment. Using three pristine (unaffected by precipitation) ash samples, we quantify the release of PTEs (Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V, Zn) and major cations typical of ash leachates (Mg, Na, Ca, K) in multiple simulated lung fluid (SLF) preparations and under varying experimental parameters (contact time and solid to liquid ratio). Data are compared to a standard water leach (WL) to ascertain whether the WL can be used as a simple proxy for SLF leaching. The main findings are: PTE concentrations reach steady-state dissolution by 24 h, and a relatively short contact time (10 min) approximates maximum dissolution; PTE dissolution is comparatively stable at low solid to liquid ratios (1:100 to 1:1000); inclusion of commonly used macromolecules has element-specific effects, and addition of a lung surfactant has little impact on extraction efficiency. These observations indicate that a WL can be used to approximate lung bioaccessible PTEs in an eruption response situation. This is a useful step towards standardizing in vitro methods to determine the soluble-element hazard from inhaled ash.

Effects of process factors on the performance of electrochemical disinfection for wastewater in a continuous-flow cell reactor.

Although electrochemical disinfection has been shown to be an effective approach to inactivate bacteria in saline water, the effects of process parameters and reactor designfor its application in low-salinity water have not been well understood. In this study, factorial experiments were performed to investigate the direct and confounded effects of applied current (5-20 mA), contact time (2.5-20 min), anode surface area (185-370 cm2), and chloride concentration (50-400 mg L-1) on thedisinfection efficiency in fresh water andthe secondary effluent of municipal wastewater. An electrochemical disinfection reactor cell with an internal volume of 75 cm3 was designed and fabricated. Residence time distribution analysis showed thatthe internal mixing of the reactor is similar to that of adispersedplug-flow reactor. All studied process parameters showed significant effect on the kill efficiency, with the applied current and contact time having the most dominant effect. Although theeffect of chloride concentration, which isresponsible for electrochemical production of free chlorine in water, isstatistically significant, it isnot as prominent as those reported for high salinity water. A synergistic effect between chloride concentration and anode surface area was identified, leading to high kill efficiency (99.9%, 3 log kill) at low current density (0.0135 mA cm-2). Response surface modeling results suggested that a scaled-up disinfection reactor can be designed using large anode surface area with long contact time for high chloride water (400 mg L-1) or high current density with short contact time for low chloride water (50 mg L-1). The power requirement of a portable system treating 37.85 m3 day-1 (10,000 gpd) of municipal wastewater was estimated to be 1.9 to 8.3 kWto achieve a 3 log kill, depending on the reactor design.

Grape seed extract against Aichi virus infectivity in model foods and contact surfaces

Aichi virus (AiV) is an enteric virus that affects humans and is prevalent in sewage waters. Effective strategies to control its spread need to be explored. This study evaluated grape seed extract (GSE) for: a) antiviral potential towards AiV infectivity at 37 °C and room temperature (RT); b) antiviral behavior in model foods (apple juice (AJ) and 2% fat milk) and also simulated gastric environments; and c) potential application as a wash solution on stainless steel surfaces. GSE at 0.5 mg/mL decreased AiV suspensions containing ~4.75 log PFU/mL to titer levels that were not detected after 30 s at both 37 °C and RT. Infectious AiV titers were not detected after 5 min treatment with 1 mg/mL GSE at 37 °C in AJ. GSE at 2 mg/mL and 4 mg/mL in 2% fat milk decreased AiV after 24 h by 1.18 and 1.57 log PFU/mL (4.75 log PFU/mL to 2.86 and 3.25 log PFU/mL), respectively. As a surface wash, GSE at 1 mg/mL after 30 s decreased AiV to undetectable levels under clean conditions. With organic load (mimicking unclean conditions), 2 and 4 mg/mL GSE reduced AiV after 5 min by 1.13 and 1.71 log PFU/mL, respectively. Overall, GSE seems to be a promising antiviral agent against AiV at low concentrations and short contact times.

Performance of downpipe treatment system for removal of dissolved metals from roof runoff

Abstract Untreated metal roof runoff can contribute elevated zinc and copper to receiving waterways, with associated ecotoxic impacts on the aquatic ecosystem. The majority of the metals in roof runoff are in dissolved form, which can be difficult to remove with conventional stormwater treatment systems. Treatment materials such as limestone and zeolite are capable of removing dissolved metals, but most research to date has only assessed the performance of such materials using synthetic runoff and long contact times. This study assessed the performance of limestone, zeolite and waste mussel shells in a vertical downpipe configuration with short contact time using actual metal roof runoff. Metal removal was compared under flowrates of 1 L/min and 3 L/min, material compaction level (less/more), and material depth (1 m and 0.5 m). A 93%–99% reduction was achieved in dissolved zinc by all treatment materials for all flowrates, compaction levels and depths. Higher variance in dissolved Cu removal rates were observed, with material depth found to have the greatest influence on performance: 84%–99% removal rates were achieved by the three materials at 1 m depth, but for 0.5 m depths, 44%–99%, 34%–92%, and 47%–93% removal were achieved by zeolite, limestone, and waste mussel shells respectively. The mussel shell removal performance was comparable to zeolite and limestone, yet it provides the added benefit of using a waste resource that would otherwise be disposed of to landfill. While this study demonstrates the potential of waste mussel shells for dissolved metal treatment, long term field trials and experimental analysis of the removal mechanisms of waste mussel shells would enable optimization of this treatment technology.

Short contact time CH4 partial oxidation over Ni based catalyst at 1.5 MPa

Gas-to-liquid technologies to produce Fischer–Tropsch fuels are economically sustainable at very large scales— 30 000bbld−1. To achieve a viable process at a scale less than 100bbld−1 requires a compact design, like a short contact time reactor and mass manufacturing to reduce capital cost. We tested the activity of 2.25%Ni/0.1%Ru/CeO2 supported on FeCrAl gauze (Ni2510) to partially oxide methane at a contact time less than 0.050s. Besides, the very short contact time, an additional feature of this work is that the catalyst activated on-stream without a hydrogen pretreatment step. The reactor operated at 1.5MPa, 800°C to 950°C, and a CH4/O2 ratio varying from 1.6 to 1.8 v/v. Methane partially oxidized carbon monoxide (direct mechanism) rather than combusting to CO2 followed by steam reforming to CO (indirect mechanism). The following phenomena support the direct mechanism hypothesis: (i) the selectivity improved when reducing residence time, (ii) the mass spectrometer detected both O2 and CO at the effluent (simultaneously), (iii) metallic Ni clusters on the Ni2510 were absent under reaction conditions based on in situ X-ray absorption spectroscopy. Loading Ni/Al2O3 powder downstream of the Ni2510 increased syngas yield, as this catalyst promoted steam and dry reforming. Soot forms upstream of the Ni2510 catalyst via a retro-propagation mechanism in which methyl radicals produced on the catalyst surface react with the incoming feed gas.

CO2 introduced the coagulation-flocculation of oil acidized wastewater: pollutant removal and cost analysis.

It is difficult to adjust the pH of oil acidized wastewater rich in Ca2+, thus hindering the polyacrylamide (PAM) flocculation. This study aims at accelerating the flocculation process by introducing CO2 into the water to induce the formation of CaCO3 nuclei. The order in which CO2 and NaOH were added affected the floc structures. Compared with CO2-NaOH-PAM, the flocs of NaOH-CO2-PAM were more compact and more CaCO3 crystals were formed. The aqueous Ca2+ involved in the reaction reached 20%, and CO2 utilization was enhanced. The settling time was shortened by half (from 20 to 3 min), and NaOH consumption was reduced by one-tenth (from 0.03 to 0.003 mol), hence significantly reducing the costs. Due to the higher settling rate and shorter contact time, the NaOH-CO2-PAM flocs adsorbed less so that the residual oil was 124 mg·L-1, while in the case of CO2-NaOH-PAM it was 88 mg·L-1. As a promising coagulation aid, CO2 can also be used to mineralize pollutants in wastewater.

Pseudoviruses for the assessment of coronavirus disinfection by ozone.

The COVID-19 pandemic has severely impacted public health worldwide. Evidence of SARS-CoV-2 transmission via aerosols and surfaces has highlighted the need for efficient indoor disinfection methods. For instance, the use of ozone gas as a safe and potent disinfectant against SARS-CoV-2 virus is of particular interest. Here we tested the use of pseudoviruses as a model for evaluating ozone disinfection of the coronavirus at ozone concentrations of 30, 100, and 1000 ppmv. Results show that ozone disinfection rate of pseudoviruses was similar to that of coronavirus 229E (HuCoV-229E) at short contact times, below 30 min. Viral infection decreased by 95% following ozone exposure for 20 min at 1000 ppmv, 30 min at 100 ppmv and about 40 min at 30 ppmv. This findings mean that ozone is a powerful disinfectant toward the enveloped pseudovirus even at low ozone exposure. We also showed that viral disinfection occurs on various contaminated surfaces, with a positive association between disinfection and surface hydrophilicity. Infected surfaces made of aluminum alloy, for example, were better disinfected with ozone as compared to brass, copper, and nickel surfaces. Lastly, we demonstrate the advantage of ozone over liquid disinfectants by showing similar viral disinfection on top, side, bottom, and interior surfaces. Overall, our study demonstrates the potential use of ozone gas disinfection to combat the COVID-19 outbreak.Electronic supplementary materialThe online version of this article (10.1007/s10311-020-01160-0) contains supplementary material, which is available to authorized users.

A non-premixed reactive volatilization reactor for catalytic partial oxidation of low volatility fuels at a short contact time

This work presents a novel non-premixed opposed-flow reactive volatilization reactor that simultaneously vaporizes and partially oxidizes low volatility liquid hydrocarbons at a short contact time (<12 ms).

Preparing A University Hospital Neonatal Intensive Care Unit for Covid-19 Pandemic and Country Lockdown

Jordan is one of the earliest countries that took a very strict approach to contain COVID-19 pandemic by declaring a country lock down. Our neonatal intensive care unit is a level three 30 beds unit. The shortage of neonatal nurses, doctors, and of respiratory support devices are the major existing challenges. During COVID-19 pandemic, those two issues were magnified. This paper will shortly discuss the measures taken as a preparedness for COVID-19 Pandemic in our unit. Team development and work schedule: The medical knowledge about COVID-19 was foggy, however; teamwork is the only ev-ident thing. Our team included, the neonatologists, pediatric intensivist, pediatric pul-monologists, in addition to the infectious disease specialist. The team also included three of our senior residents, and the neonatal unit head nurse. To enhance communication, we created a WhatsApp group (Peds COVID -19). Among this group, unidentified Patients’ information, in addition to recent publications and sci-entific opinions, were shared. Meeting with the obstetric department was done to famil-iarize both teams with the measures taken on both sides. The neonatal care is provided by two neonatologists. The in-house care providers are the pediatric residents. Senior residents are well-trained on neonatal resuscitation, endotra-cheal intubation, and umbilical venous catheterization. During COVID-19 lock down, residents were split into separate teams. Neonatal team, the pediatric floor team, and the emergency room team, each team had their sleeping room and lounges. The consultants did rounds daily, the in-house team consisted of two senior residents, and a junior resident. they did a 24-hour shift every four days and are off duty for the next three days. Regarding the nursing staff schedule, their work schedule changed from an 8- hour shift to a 12- hour shifts schedule. The aim was to promote staff well-being, minimize the number of staff who could potentially be exposed to a COVID-19 case, and therefore will need to be quarantined. Visitation policy: Mothers could come at any time, but fathers could visit briefly. Parents were requested to wear gowns and face masks. We continued to encourage breast feeding, and we continued to receive expressed breast milk from mothers at home. Neonatal isolation area: A separate area was designated for isolating asymptomatic infants born to COVID-19 positive or suspected mothers, another area was designated for sick newborns, both areas were outside the current NICU. A separate nursing staff were assigned to take care of the isolated newborns. Infection control measures: The unit medical and nursing staff were instructed to stay home if feeling unwell, with fever or respiratory illness. They were also instructed to declare any contact with sick individuals. Wearing face mask and maintaining social distancing whenever possible, is a policy we adopted very early. When providing medical care to suspected cases, the staff were instructed to follow the hospital protocol. Management plan: After reviewing the available literature of COVID-19 infection a management flow chart was constructed to standardize the care. It contains the main steps and principles of management. It was circulated to all residents, the hospital administration, and to the hospital infection control unit (Table1). This chart is designed to help with the initiation of the care. The management process might vary according to the patient situation, in addition to the change of the current COVID-19 knowledge that will mandate a change in the implemented guidelines. Neonatal units should have an in-house policy that will guarantee standardization of care, better communication with different disciplines, and most importantly policies that could decrease the transmission risk of the corona virus among the staff and neonatal patients. Infection control measures, minimum staff on duty, and shorter contact time, are the most important items in such policies.

Improving Biological Treatment of Real Bilge Wastewater With Zero Valent Iron and Activated Charcoal Addition.

From the ships engine rooms a recalcitrant wastewater is produced called “bilge” which contains oil, metal working fluids, surfactants, and salinity. This study investigated the treatment of real bilge wastewater in short experiments using the following processes: (i) anaerobic digestion with granular sludge and ZVI addition for enhancement of methane production, (ii) activated charcoal addition to biological treatment (aerobic and anaerobic) for Chemical Oxygen Demand (COD) significant reduction and (iii) combination of ZVI and anaerobic charcoal addition for high performance treatment. The addition of ZVI in anaerobic sludge resulted in higher performance mostly in cumulative CH4 production. The microbial profile of anaerobic granular sludge exposed to ZVI was determined and Acetobacterium and Arcobacter were the most dominant bacteria genera. Activated charcoal achieved higher COD removal, compared to biological degradation (aerobic and anaerobic). The combination of the two mechanisms, activated charcoal and biomass, had higher COD removal only for aerobic biomass. The combination of ZVI and activated charcoal to anaerobic digestion resulted in higher CH4 production and significant COD removal in short contact time.

A meta-analysis of metal biosorption by suspended bacteria from three phyla

Biosorption of heavy metals by bacterial biomass has been the subject of significant research interest in last decades due to its efficiency, relatively low cost and minimal negative effects for the surrounding environment. In this meta-analysis, the biosorption efficiencies of different bacterial strains for Cu(II), Cd(II), Zn(II), Cr(III), Mn(II), Pb(II) and Ni(II) were evaluated. Optimum conditions for the biosorption process such as initial metal concentration, temperature, pH, contact time, metal type, biomass dosage and bacterial phyla, were evaluated for each heavy metal. According to the results, the efficiencies of bacterial biomass for removal of heavy metal were as follows: Cd(II) > Cr(III) > Pb(II) > Zn(II) > Cu(II) > Ni(II) > Mn(II). Firmicute phyla showed the highest overall (living and dead) biosorption efficiency for heavy metals. Living biomass of Proteobacteria had the best biosorption performance. Living bacterial biomass was significantly more efficient in biosorption of Cu(II), Zn(II) and Pb(II) than dead biomass. The maximum biosorption efficiency of bacterial strains for Cd(II), Pb(II) and Zn(II) was achieved at pH values between 6 and 7.5. High temperatures (>35 °C) reduced the removal efficiencies for Cu(II) and Zn(II) and increased the efficiencies for Cd(II) and Cr(III) ions. The maximum biosorption efficiency of non-essential heavy metals occurred with short contact times (<2 h). Essential metals such as Zn and Cu were more efficiently removed with long biosorption durations (>24 h). The mean biosorption capacity of bacterial biomass was between 71.26 and 125.88 mg g−1. No publication bias existed according to Egger’s and Begg’s test results.

Sono-assisted adsorption of acid violet 7 and basic violet 10 dyes from aqueous solutions: Evaluation of isotherm and kinetic parameters

In this study, the removal of acid violet 7 (AV7) and basic violet 10 (BV10) synthetic dyes was investigated using fly ash alone, ultrasound (40 kHz) alone, and combined ultrasound/fly ash with various experimental parameters such as fly ash dose, contact time, and initial concentration of dye. The adsorption capacity of the ultrasound/fly ash process increased from 5.10 to 7.43 mg g-1 for AV7, and increased from 5.16 to 7.51 mg g-1 for BV10 compared with using fly ash alone. The sono–assisted adsorption process was successful in improving the dye uptake capacity with cavitation bubbles and acoustic waves, and thus AV7 and BV10 were removed with a shorter contact time and lower fly ash dose. Obtained regeneration and reuse experiment results showed that the fly ash could be reused for four consecutive cycles of the sono–assisted adsorption process, while fly ash could be reused for two consecutive cycles of the adsorption process. The adsorption kinetics for AV7 and BV10 onto fly ash fitted Lagergren’s first–order adsorption kinetic model well. The Langmuir isotherm best described the adsorption with fly ash alone and ultrasound/fly ash process for AV7 and BV10.

Behaviors of Adsorption and Elution on Amidoxime Resin for Gallium, Vanadium, and Aluminium Ions in Alkaline Aqueous Solution

ABSTRACT For recovery of gallium from Bayer liquor, adsorption, and elution on amidoxime resin for gallium (Ga), vanadium (V), and aluminum (Al) ions in alkaline solution were systematically investigated by batch and column experiment. Amidoxime resin did not adsorb Al. The adsorption separation efficiency of Ga and V increased with increasing NaOH concentration and decreasing temperature and contact time. The adsorption kinetics of Ga and V are fit by a pseudo-second-order model. The adsorption isotherms of Ga and V could be fit well by the Langmuir model. Gallium was easily eluted using low concentration acid (1~2 mol/L H+), but it was difficult to elute V. Although high concentration acid could elute 70% of V, this treatment would destroy resin. With high NaOH concentration and a long eluting time, more than 50% of V could be eluted at temperatures greater than 50°C, and NaOH did no damage to the resin. The optimum condition of Ga separation from V and Al is at low temperature with short contact time and high NaOH concentration. After adsorption and desorption, a high-purity Ga is obtained, from which V can be recovered V by elution with a strong NaOH concentration at 50°C. FT-IR spectra and XPS showed that the adsorption mechanism of Ga was only related to interaction with oxygen atoms of amidoxime groups (C = NOH). Furthermore, the adsorption mechanism of V was related to both nitrogen and oxygen atoms of amidoxime groups that caused the difficulty of desorbing V from resin.

The Hydrodeoxygenation of Glycerol over NiMoSx: Catalyst Stability and Activity at Hydropyrolysis Conditions

AbstractCatalytic activity tests were run to elucidate the chemistry and catalyst stability for the hydrodeoxygenation of glycerol and other aliphatic oxygenates over a NiMoSx/Al2O3 catalyst at different pretreatments at hydropyrolysis conditions in a continuous flow reactor. Reactivity metrics were developed to quantify and compare the reactivity of NiMo for deoxygenation, hydrogenation, and C−C cleavage. Activity experiments showed sulfided NiMo and reduced NiMo catalysts had similar deoxygenation and hydrogenation activity for glycerol HDO at 400 °C and 270 psig H2 with the NiMoSx catalyst showing higher C−C cleavage activity. Without a sulfur co‐feed, both the NiMoSx and NiMoOx catalysts lost &gt;40 % deoxygenation activity over 30 h time on stream. With a 2100 ppm H2S co‐feed the NiMoSx catalyst showed a 12 times decrease in the deactivation rate for deoxygenation and 6 time decrease in the deactivation rate for hydrogenation. The main products at high conversion were propylene, propane, ethylene, methane, CO, methanol, ethanol, and 1‐propanol. At low conversion, the major products were unsaturated allyl alcohol, acrolein, hydroxyacetone, and acetaldehyde. With no H2S co‐feed at short contact times, there was a significant amount of carbon loss possibly due to condensation reactions, while at 2100 ppm H2S in the feed, the carbon balance was 102.4 %. Temperature programmed oxidation of the spent NiMoSx catalysts after 30 h of glycerol HDO without an H2S co‐feed showed that one of the causes of deactivation was coking.

Leg Stiffness and Vertical Stiffness of Habitual Forefoot and Rearfoot Strikers during Running.

Foot strike patterns influence the running efficiency and may be an injury risk. However, differences in the leg stiffness between runners with habitual forefoot (hFFS) and habitual rearfoot (hRFS) strike patterns remain unclear. This study aimed at determining the differences in the stiffness, associated loading rate, and kinematic performance between runners with hFFS and hRFS during running. Kinematic and kinetic data were collected amongst 39 runners with hFFS and 39 runners with hRFS running at speed of 3.3 m/s, leg stiffness (Kleg), and vertical stiffness (Kvert), and impact loads were calculated. Results found that runners with hFFS had greater Kleg (P = 0.010, Cohen′s d = 0.60), greater peak vertical ground reaction force (vGRF) (P = 0.040, Cohen′s d = 0.47), shorter contact time(tc) (P < 0.001, Cohen′s d = 0.85), and smaller maximum leg compression (ΔL ) (P = 0.002, Cohen′s d = 0.72) compared with their hRFS counterparts. Runners with hFFS had lower impact peak (IP) (P < 0.001, Cohen′s d = 1.65), vertical average loading rate (VALR) (P < 0.001, Cohen′s d = 1.20), and vertical instantaneous loading rate (VILR) (P < 0.001, Cohen′s d = 1.14) compared with runners with hRFS. Runners with hFFS landed with a plantar flexed ankle, whereas runners with hRFS landed with a dorsiflexed ankle (P < 0.001, Cohen′s d = 3.35). Runners with hFFS also exhibited more flexed hip (P = 0.020, Cohen′s d = 0.61) and knee (P < 0.001, Cohen′s d = 1.15) than runners with hRFS at initial contact. These results might indicate that runners with hFFS were associated with better running economy through the transmission of elastic energy.