Residence Time Research Articles

Atrial fibrillation increases thrombogenicity of LVAD therapy.

This study investigates the hypothesis that presence of atrial fibrillation (AF) in LVAD patients increases thrombogenicity in the left ventricle (LV) and exacerbates stroke risk. Using an anatomical LV model implanted with an LVAD inflow cannula, we analyze thrombogenic risk and blood flow patterns in either AF or sinus rhythm (SR) using unsteady computational fluid dynamics (CFD). To analyze platelet activation and thrombogenesis in the LV, hundreds of thousands of platelets are individually tracked to quantify platelet residence time (RT) and shear stress accumulation history (SH). The irregular and chaotic mitral inflow associated with AF results in markedly different intraventricular flow patterns, with profoundly negative impact on blood flow-induced stimuli experienced by platelets as they traverse the LV. Twice as many platelets accumulated very high SH in the LVAD + AF case, resulting in a 36% increase in thrombogenic potential score, relative to the LVAD + SR case. This supports the hypothesis that AF results in unfavorable blood flow patterns in the LV adding to an increased stroke risk for LVAD + AF patients. Quantification of thrombogenic risk associated with AF for LVAD patients may help guide clinical decision-making on interventions to mitigate the increased risk of thromboembolic events.

Single-molecule imaging reveals a direct role of CTCF's zinc fingers in SA interaction and cluster-dependent RNA recruitment.

CTCF is a zinc finger protein associated with transcription regulation that also acts as a barrier factor for topologically associated domains (TADs) generated by cohesin via loop extrusion. These processes require different properties of CTCF-DNA interaction, and it is still unclear how CTCF's structural features may modulate its diverse roles. Here, we employ single-molecule imaging to study both full-length CTCF and truncation mutants. We show that CTCF enriches at CTCF binding sites (CBSs), displaying a longer lifetime than observed previously. We demonstrate that the zinc finger domains mediate CTCF clustering and that clustering enables RNA recruitment, possibly creating a scaffold for interaction with RNA-binding proteins like cohesin's subunit SA. We further reveal a direct recruitment and an increase of SA residence time by CTCF bound at CBSs, suggesting that CTCF-SA interactions are crucial for cohesin stability on chromatin at TAD borders. Furthermore, we establish a single-molecule T7 transcription assay and show that although a transcribing polymerase can remove CTCF from CBSs, transcription is impaired. Our study shows that context-dependent nucleic acid binding determines the multifaceted CTCF roles in genome organization and transcription regulation.

The Effect of Residence Time and Stream Restrictions on the Precursors’ Structure and Coke Morphology

AbstractIn this work, the precursors and intermediates of catalytic dehydrogenation of toluene, ethylbenzene, and styrene (TES) stream were detected, quantified, and classified at 750–800 °C. The classification approach for tracing the structural changes of the produced precursors was designed based on different residence times of intermediates, leading to the presentation of a morphology prediction model for precipitated coke according to the restriction of stream pass. The results revealed that the coke structure of encapsulating is formed by heavier precursors produced at a restricted direction of flow. On the other hand, the filamentous coke made from lighter precursors is formed at smooth streams with no restricted areas.

Naturally derived organic biochar as an alternative to commercially activated carbon in the oxygen removal of seafood processing wastewater

AbstractBACKGROUNDThe seafood processing industries are tremendously increasing in numbers which eventually discharge a large quantity of wastewater with a high range of biochemical oxygen demand (BOD) and chemical oxygen demand (COD), directly into the aquatic environment. A high level of BOD and COD in wastewater pertains to a higher level of pollution which must be reduced to prevent hazardous impacts on ecosystems. The main objective of the research aimed to develop cost‐effective biochar and to remove BOD and COD from processing wastewater using two natural biomasses: water hyacinth and sugarcane bagasse.RESULTSNaOH‐treated and non‐treated biochar for both water hyacinth as well as sugarcane bagasse were prepared through the process of pyrolysis carried out at 600 °C with three different residence times of 30, 45 and 60 min. The wastewater was initially analyzed for BOD and COD levels. The results showed that among all the groups of biochars, the water hyacinth NaOH‐treated biochar pyrolyzed at 600 °C for 60 min exhibited significantly (P < 0.05) higher levels of reduction in BOD (86.6 ± 0.03%) and COD (94.3 ± 0.05%) at a residence time of 60 min in D2 (0.5 g (250 mL)−1). The maximum removal efficiency was observed for water hyacinth NaOH‐treated biochar pyrolyzed at 600 °C for 60 min.CONCLUSIONThe removal efficiencies of organic load revealed that the treated biochars exhibited a better reduction of nutrients. The biochar efficiencies when compared with those of activated carbon exhibited a higher removal level. The present research can be used to reduce BOD and COD levels in wastewater treatments. © 2024 Society of Chemical Industry (SCI).

How important is carbon sequestration in phytoliths within the soil?

Abstract Background and aims An overlooked fraction of the terrestrial carbon (C) pool is that associated with biogenic silica deposited in plants (phytoliths), so-called PhytOC. This fraction is small compared with the main C pools, but is of interest because it could be a long-term C sink as phytoliths may protect organic C from mineralization. However, the topic is hotly contested and unclear due to both methodological and theoretical limitations. Scope We aim to review this topic, with specific emphasis on: (i) the range of C concentrations associated with phytoliths; (ii) soil phytolith preservation and subsequent organic C mineralization; and (iii) global estimates of C sequestration within PhytOC. Conclusions Recent work has suggested that [PhytOC] could be much greater than currently acknowledged, but also highly variable and dependent on cell silicification types. A short case study using cryo‐Scanning Electron Microscopy (cryo-SEM), X‐ray microanalysis (EDX), plus Focused Ion Beam (FIB) and Scanning Transmission Electron Microscopy (STEM) on the culms of a sedge (Schoenus caespititius) confirmed this thinking. Understanding of both phytolith and PhytOC fates in soil is poor. We suggest that phytolith residence time should be seen as a gradient. Such a continuum is explained by different phytolith sizes, types and chemistry, which will also have contrasting PhytOC. Our estimation of C sequestration as PhytOC each year (11–190 Tg C yr−1) represents between < 1% and 13% of the C that could be sequestered globally in soils (estimated at 1400 Tg C yr−1). We conclude that (1) more research is needed to improve our understanding of the formation and fate of PhytOC in terrestrial ecosystems and (2) it would be unwise to put our faith in PhytOC sequestration or other related methodologies to “solve” the climate crisis.

Advancements in Nanosystems for Ocular Drug Delivery: A Focus on Pediatric Retinoblastoma

The eye’s complex anatomical structures present formidable barriers to effective drug delivery across a range of ocular diseases, from anterior to posterior segment pathologies. Emerging as a promising solution to these challenges, nanotechnology-based platforms—including but not limited to liposomes, dendrimers, and micelles—have shown the potential to revolutionize ophthalmic therapeutics. These nanocarriers enhance drug bioavailability, increase residence time in targeted ocular tissues, and offer precise, localized delivery, minimizing systemic side effects. Focusing on pediatric ophthalmology, particularly on retinoblastoma, this review delves into the recent advancements in functionalized nanosystems for drug delivery. Covering the literature from 2017 to 2023, it comprehensively examines these nanocarriers’ potential impact on transforming the treatment landscape for retinoblastoma. The review highlights the critical role of these platforms in overcoming the unique pediatric eye barriers, thus enhancing treatment efficacy. It underscores the necessity for ongoing research to realize the full clinical potential of these innovative drug delivery systems in pediatric ophthalmology.

Characterization of the Bottlenecks and Pathways for Inhibitor Dissociation from [NiFe] Hydrogenase.

[NiFe] hydrogenases can act as efficient catalysts for hydrogen oxidation and biofuel production. However, some [NiFe] hydrogenases are inhibited by gas molecules present in the environment, such as O2 and CO. One strategy to engineer [NiFe] hydrogenases and achieve O2- and CO-tolerant enzymes is by introducing point mutations to block the access of inhibitors to the catalytic site. In this work, we characterized the unbinding pathways of CO in the complex with the wild-type and 10 different mutants of [NiFe] hydrogenase from Desulfovibrio fructosovorans using τ-random accelerated molecular dynamics (τRAMD) to enhance the sampling of unbinding events. The ranking provided by the relative residence times computed with τRAMD is in agreement with experiments. Extensive data analysis of the simulations revealed that from the two bottlenecks proposed in previous studies for the transit of gas molecules (residues 74 and 122 and residues 74 and 476), only one of them (residues 74 and 122) effectively modulates diffusion and residence times for CO. We also computed pathway probabilities for the unbinding of CO, O2, and H2 from the wild-type [NiFe] hydrogenase, and we observed that while the most probable pathways are the same, the secondary pathways are different. We propose that introducing mutations to block the most probable paths, in combination with mutations to open the main secondary path used by H2, can be a feasible strategy to achieve CO and O2 resistance in the [NiFe] hydrogenase from Desulfovibrio fructosovorans.

Residents underestimate their robotic performance: evaluating resident robotic console participation time

Lack of formal national robotic curriculum results in a void of knowledge regarding appropriate progression of autonomy in robotic general surgery training. One midwestern academic surgical training program has demonstrated that residents expect to independently operate more on the robotic console than they perceive themselves to do. As such, our study sought to evaluate expectations of residents and faculty regarding resident participation versus actual console participation time (CPT) at a community general surgery training program. We surveyed residents and faculty in two phases. Initially, participants were asked to reflect on their perceptions and expectations from the previous six months. The second phase included surveys (collected over six months) after individual cases with subjective estimation of participation versus CPT calculated by the Intuitive Surgical, Inc. MyIntuitive application. Using Mann–Whitney U-Test, we compared resident perceptions of CPT to actual CPT by case complexity and post-graduate year (PGY). Faculty (n = 7) estimated they allowed residents to complete a median of 26–50% of simple and 0–25% of complex cases in the six months prior to the study. They expected senior residents (PGY-4 and PGY-5) to complete more: 51–75% of simple and 26–50% of complex cases. Residents (n = 13), PGY-2–PGY-5, estimated they completed less than faculty perceived (0–25% of simple and 0–25% of complex cases). Sixty-six post-case (after partial colectomy, abdominoperoneal resection, low anterior resection, cholecystectomy, inguinal/ventral hernia repair, and others) surveys were completed. Residents estimated after any case that they had completed 26–50% of the case. However, once examining their MyIntuitive report, they actually completed 51–75% of the case (median). Residents, especially PGY-4 and 5, completed a higher percentage than estimated of robotic cases. Our study confirms that residents can and should complete more of (and increasingly complex) robotic cases throughout training, like the transition of autonomy in open and laparoscopic surgery.

Skin pharmacokinetics of miltefosine in the treatment of post-kala-azar dermal leishmaniasis in South Asia.

Post-kala-azar dermal leishmaniasis (PKDL) arises as a dermal complication following a visceral leishmaniasis (VL) infection. Current treatment options for PKDL are unsatisfactory, and there is a knowledge gap regarding the distribution of antileishmanial compounds within human skin. The present study investigated the skin distribution of miltefosine in PKDL patients, with the aim to improve the understanding of the pharmacokinetics at the skin target site in PKDL. Fifty-two PKDL patients underwent treatment with liposomal amphotericin B (20 mg/kg) plus miltefosine (allometric dosing) for 21 days. Plasma concentrations of miltefosine were measured on study days 8, 15, 22 and 30, while a punch skin biopsy was taken on day 22. A physiologically based pharmacokinetic (PBPK) model was developed to evaluate the distribution of miltefosine into the skin. Following the allometric weight-based dosing regimen, median miltefosine concentrations on day 22 were 43.73 µg/g (IQR: 21.94-60.65 µg/g) in skin and 33.29 µg/mL (IQR: 25.9-42.58 µg/mL) in plasma. The median individual concentration ratio of skin to plasma was 1.19 (IQR: 0.79-1.9). In 87% (45/52) of patients, skin exposure was above the suggested EC90 PK target of 10.6 mg/L associated with in vitro susceptibility. Simulations indicated that the residence time of miltefosine in the skin would be more than 2-fold longer than in plasma, estimated by a mean residence time of 604 versus 266 hours, respectively. This study provides the first accurate measurements of miltefosine penetration into the skin, demonstrating substantial exposure and prolonged retention of miltefosine within the skin. These findings support the use of miltefosine in cutaneous manifestations of leishmaniasis. In combination with parasitological and clinical data, these results are critical for the future optimization of combination therapies with miltefosine in the treatment of PKDL.

Testing the hypothesis that solvent exchange limits the rates of calcite growth and dissolution.

It is established that the rates of solvent exchange at interfaces correlate with the rates of a number of mineral reactions, including growth, dissolution and ion sorption. To test if solvent exchange is limiting these rates, quasi-elastic neutron scattering (QENS) is used here to benchmark classical molecular dynamics (CMD) simulations of water bound to nanoparticulate calcite. Four distributions of solvent exchanges are found with residence times of 8.9 ps for water bound to calcium sites, 14 ps for that bound to carbonate sites and 16.7 and 85.1 ps for two bound waters in a shared calcium-carbonate conformation. By comparing rates and activation energies, it is found that solvent exchange limits reaction rates neither for growth nor dissolution, likely due to the necessity to form intermediate states during ion sorption. However, solvent exchange forms the ceiling for reaction rates and yields insight into more complex reaction pathways.

Settling velocity of atmospheric particles in seawater: Based on hydrostatic sedimentation method using video imaging techniques

When atmospheric particles deposit to the ocean, their settling velocities and residence times associated are critical for their effects on oceanic ecosystems. We developed a hydrostatic sedimentation method using video imaging techniques to track particles of 5–20 μm in diameter falling into seawater and determine the particle settling velocities in relation to their diameter, shape, organic matter contained, and seawater salinity. The measured settling velocities varied from 0.025 to 0.41 mm/s. Irregular particle shape and organic matter contained in particles also, however, reduced the values. The settling velocities were decelerated by the dissolution process of particle in seawater. Combined with the experimental results, a formula for calculating the settling velocity formulae for atmospheric particles was estimated. Using this equation, the residence time of particles is estimated to be less than one month in continental shelf sea and more than 100 days in the oceans.

Quantification of water exchange across the blood-brain barrier using noncontrast MR fingerprinting.

A method is proposed to quantify cerebral blood volume ( ) and intravascular water residence time ( ) using MR fingerprinting (MRF), applied using a spoiled gradient echo sequence without the need for contrast agent. An in silico study optimized an acquisition protocol to maximize the sensitivity of the measurement to and changes. Its accuracy in the presence of variations in , , and was evaluated. The optimized protocol (scan time of 19 min) was then tested in a exploratory healthy volunteer study (10 volunteers, mean age 24 3, six males) at 3 T with a repeat scan taken after repositioning to allow estimation of repeatability. Simulations show that assuming literature values for and , no variation in , while fitting only and , leads to large errors in quantification of and , regardless of noise levels. However, simulations also show that matching , , , and , simultaneously is feasible at clinically achievable noise levels. Across the healthy volunteers, all parameter quantifications fell within the expected literature range. In addition, the maps show good agreement between hemispheres suggesting physiologically relevant information is being extracted. Expected differences between white and gray matter (p < 0.0001) and (p < 0.0001) are observed, and show no significant differences, p = 0.4 and p = 0.6, respectively. Moderate to excellent repeatability was seen between repeat scans: mean intra-class correlation coefficient of , , , and . We demonstrate that regional simultaneous quantification of , , , and using MRF is feasible in vivo.

Zircon trace element fingerprint of changing tectonic regimes in Permian rhyolites from the Central European Lowlands

AbstractThe late Carboniferous/early Permian post-collisional rhyolites (305–285 Ma) that formed in Central Europe have generally similar whole rock compositions to that of older Late-Variscan rhyolites (330–310 Ma). However, data compilation combining zircon age with the chemical composition of rhyolites from 20 units shows a trend of increasing zircon saturation temperature with decreasing age. This trend is particularly well identified in rhyolites from the Central European Lowlands (CEL)—consisting of the NE German and NW Polish Basin—and also correlates their location with the zircon saturation temperature increasing from SE to NW from 750°C to 850°C. We infer that these higher temperatures of zircon saturation reflect a contemporaneous change in the tectonic setting from collisional to divergent, reflecting the onset of the Central European continental rifting. This interpretation is further corroborated by the trace element compositions of the CEL zircons, which resembles zircon crystallized in a divergent setting. Interestingly, the zircon formed globally in this type of setting is chemically diverse, especially considering uranium concentration. For example, zircon from locations dominated by mafic magma fractionation, such as rhyolites from Iceland, have low U concentrations and low U/Yb ratios. On the other hand, zircon formed in rhyolites in rifted margins, like western North America, tends to have much higher U and U/Yb ratios. Such high concentrations are not observed in zircon from the CEL, suggesting that the mantle input could be higher and residence times within continental crust shorter than those for rhyolites from the Cenozoic western USA. This may, in turn, suggest that the region might have been affected by a hot spot, similar to that responsible for rhyolite formation of the Snake River Plain. Graphical abstract

Dual-ROS-scavenging and dual-lingering nanozyme-based eye drops alleviate dry eye disease

Efficiently removing excess reactive oxygen species (ROS) generated by various factors on the ocular surface is a promising strategy for preventing the development of dry eye disease (DED). The currently available eye drops for DED treatment are palliative, short-lived and frequently administered due to the short precorneal residence time. Here, we developed nanozyme-based eye drops for DED by exploiting borate-mediated dynamic covalent complexation between n-FeZIF-8 nanozymes (n-Z(Fe)) and poly(vinyl alcohol) (PVA) to overcome these problems. The resultant formulation (PBnZ), which has dual-ROS scavenging abilities and prolonged corneal retention can effectively reduce oxidative stress, thereby providing an excellent preventive effect to alleviate DED. In vitro and in vivo experiments revealed that PBnZ could eliminate excess ROS through both its multienzyme-like activity and the ROS-scavenging activity of borate bonds. The positively charged nanozyme-based eye drops displayed a longer precorneal residence time due to physical adhesion and the dynamic borate bonds between phenyboronic acid and PVA or o-diol with mucin. The in vivo results showed that eye drops could effectively alleviate DED. These dual-function PBnZ nanozyme-based eye drops can provide insights into the development of novel treatment strategies for DED and other ROS-mediated inflammatory diseases and a rationale for the application of nanomaterials in clinical settings.Graphical

Pharmacokinetics of famotidine in goats after intravenous administration.

There is currently limited pharmacokinetic data for the use of famotidine in goats for treatment and prevention of abomasal ulceration. The objective of this study was to determine the pharmacokinetic parameters after a single intravenous administration of famotidine (0.6 mg/kg). Famotidine was administered to six healthy goats and plasma samples were collected over a 24-h period. The famotidine concentration was measured using reverse phase high-performance liquid chromatography (HPLC). Non-compartmental analysis was then used to determine the pharmacokinetic parameters. The maximum plasma concentration was estimated at 5476.68 ± 1530.51 ng/mL and elimination half-life was estimated at 18.455 ± 13.26 min. The mean residence time was determined to be 19.85 ± 12.14 min with the apparent volume of distribution being estimated at 321.924 ± 221.667. The area under the curve was determined to be 54230.08 ± 24947.6 min*ng/mL. Total exposure and elimination half-life were less than what has been reported in cattle and horses. Future research evaluating the pharmacokinetics of subcutaneous administration and looking at the pharmacodynamics of famotidine in goats is needed to determine the effectiveness of famotidine on raising pH levels of the abomasum.

Inbuilt age, residence time, and inherited age from radiocarbon dates of modern fires and late Holocene deposits, Western Transverse Ranges, California

AbstractRadiocarbon dates from alluvial sections provide maximum deposit ages because of the time lag between formation of the dated material and deposition at the sample site, potentially producing decade‐ to century‐long biases in the dates of historic events, paleoclimatic change, fire histories, and paleoearthquakes. This bias, called the inherited age, combines the inbuilt age distribution, which reflects the age composition of the vegetation of the source area, and the residence time distribution, which includes transport and interim storage prior to final deposition. We tackle inherited age and its components by comparing charcoal dates from two modern fires in southern California, the 2020 Bobcat Fire and the 2013 Grand Fire, with a well‐dated late Holocene terrace deposit in the Pallett Creek watershed. Fifty‐six radiocarbon dates from the modern fires provide an inbuilt age distribution with a median of 25 years pre‐fire (320‐year 95% range). An inherited age distribution calculated from 175 terrace deposit dates is older, with a median age of ~90 years (850‐year 95% range). Comparing inherited ages calculated from organic‐rich versus clastic terrace deposits reveals a slight facies dependence suggesting longer residence times in clastic deposits. We develop a modeled inherited age that incorporates larger calibration uncertainties in pre‐1950s samples by combining the modern fire sample distribution with the pre‐bomb portion of the calibration curve. The modeled inherited age is younger than the terrace deposit inherited age by only 21 years, indicating inbuilt age, not long residence times, dominates inherited age in this setting. The results imply that paleoearthquakes and climatic event age estimates in the Western Transverse Ranges are up to a century too old. More broadly, dating charcoal from modern fires can constrain inherited age and the resulting distributions can improve the accuracy of dates of past environmental and tectonic events.

Extrusion-controlled lipid retention and distribution of wheat germ and its application combining exogenous starch

Wheat germ is an agricultural but low-economic by-product for animal feed or waste due to its susceptibility of hydrolytic/oxidative rancidities. Here, we use controllable extrusion to treat wheat germ, and with assistance of exogenous starch as lipid protective factor at different ratios (0:10 2:8, 3:7, 4:6). Oxidation of optimized germ extrudate was slowed down during storage, with total lipid retention rate reach up to ∼88.3%. Extrusion dynamic analysis showed that relatively high screw speed (100–150 rpm) significantly shortened mean residence time, increased axial diffusion velocity and reduced the loss of free and bound lipid. Type Ⅱ starch-lipid complex was changed to type Ⅰ during extrusion, with thermal transition peak declined. Wheat germ lipid was most evenly distributed under 100 rpm extrusion. The hydrogen bonding interaction between exogenous starch and lipids in wheat germ was strengthened, with significant modification in water absorption, water solubility, expansion and textual indexes.

Loaded layer-cake model for cosmic ray interaction around exploding super-giant stars making black holes

The experiment AMS on the International Space-Station has produced accurate cosmic ray spectra for many chemical elements, both primaries like He, C, O, Fe, other cosmic ray (CR) primaries like Ne, Mg, and Si, secondaries like Li, Be, B, and of mixed provenance, like N, Na, and Al. The AMS spectra demonstrate that interaction is seriously diminishing fluxes up to a rigidity of about 100 GV, and so the existing models for CR interaction have to be re-examined. Based on earlier well-established ideas a model is proposed here that focusses on the cosmic ray interaction first in the wind shock shell of super giant stars, when the supernova driven shock races through, and second in the OB-Superbubble surrounding the SN: These stars include both red super-giant stars and blue super-giant stars; both produce black holes in their explosion, and drive winds and jets with electric currents. Variability of these winds or jets gives rise to temporary electric fields, as has recently been demonstrated, and discharge (so lightning) acceleration gives steep spectra, with synchrotron losses to p−5 in momentum p; these spectra are typically observed in both Galactic and some extragalactic radio filaments. Analogous hadron spectra p−4 excite a flat spectrum of magnetic irregularities in the bubble zone, which in turn yields a steep dependence of residence time versus energy, with power −5/3. This spectrum is indicated by the AMS data and appears to be required to explain the CR spectra below 100 GV. The emphasis in this paper is to work out the interaction of the freshly accelerated cosmic ray particles. In the model presented here the interaction is derived as a function of time, and then integrated, or developed to long times. The model gives a rigidity dependence of the secondary/primary ratio of slope −1/3 as well as the strong reduction of the primary fluxes below a rigidity of about 100 GV, relative to a power-law injection spectrum, with slope +2. The two key aspects based on blue super-giant stars and a magnetic irregularity spectrum in the bubble zone given by lightning are (i) a much larger column of interaction, allowed because of heavy element enrichment of the interaction zone, and (ii) even He, C, and O may have a small secondary contribution, as the difference to the Fe spectrum suggests; this small secondary component is visible in the 3He/4He ratio. The model may also explain the spectrum of CR anti-protons, the gamma-ray spectra of the Galaxy and the high energy neutrino spectrum of our Galaxy, including also red super-giant stars as sources. ISM-SNe, i.e. SN Ia and neutron-star SNe, contribute to CR protons and CR He nuclei.

Biofiltration of toluene in the presence of ethyl acetate or n-hexane: Performance and microbial community.

This study describes the operation of two independent parallel laboratory-scale biotrickling filters (BTFs) to degrade different types of binary volatile organic compound (VOC) mixtures. Comparison experiments were conducted to evaluate the effects of two typical VOCs, i.e., ethyl acetate (a hydrophilic VOC) and n-hexane (a hydrophobic VOC) on the removal performance of toluene (a moderately hydrophobic VOC) in BTFs ''A" and ''B", respectively. Experiments were carried out by stabilizing the toluene concentration at 1.64 g m-3 and varying the concentrations of gas-phase ethyl acetate (0.85-2.8 g m-3) and n-hexane (0.85-2.8 g m-3) at an empty bed residence time (EBRT) of 30 s. In the presence of ethyl acetate (850 ± 55 mg m-3), toluene exhibited the highest removal efficiency (95.4 ± 2.2%) in BTF "A". However, the removal rate of toluene varied from 48.1 ± 6.9% to 70.1 ± 6.8% when 850 ± 123 mg m-3 to 2800 ± 136 mg m-3 of n-hexane was introduced into BTF "B". The high-throughput sequencing data revealed that the genera Pseudomonas and Comamonadaceae_unclassified are the core microorganisms responsible for the degradation of toluene. The intensity of the inhibitory or synergistic effects on toluene removal was influenced by the type and concentration of the introduced VOC, as well as the number and activity of the genera Pseudomonas and Comamonadaceae_unclassified. It provides insights into the interaction between binary VOCs during biofiltration from a microscopic perspective.

Prolongation of the gastric residence time of caffeine after administration in fed state: Comparison of effervescent granules with an extended release tablet

The aim of the present study was to investigate the gastroretentive capacity of different formulation principles. This was indirectly determined by the absorption behavior of caffeine from the dosage forms. A slow and continuous appearance of caffeine in the saliva of healthy volunteers was used as a parameter for a prolonged gastric retention time. For this purpose, a four-way study was conducted with twelve healthy volunteers using the following test procedures: (1) Effervescent granules with 240 mL of still water administered in fed state, (2) effervescent granules with 20 mL of still water in fed state, (3) extended release (ER) tablet with 240 mL of still water in fed state, and (4) effervescent granules with 240 mL of still water in fasted state. The initial rise of the caffeine concentrations was more pronounced after the intake of the effervescent granules in the fed state compared to that of the ER tablets. However, tmax tended to be shorter in the fed study arms following administration of the ER tablet compared to the granules. Overall, the application of active pharmaceutical ingredients formulated as effervescent granules seems to be a promising approach to increase their gastric residence time after intake in fed state.