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Coordinated contractions across the small and large intestines via the ileocecal junction (ICJ) are critical to healthy gastrointestinal function and are in part governed by myoelectrical activity. In this study, the spatiotemporal characteristics of the bioelectrical conduction across the ICJ and its adjacent regions were quantified in anesthetized rabbits. High-resolution mapping was applied from the terminal ileum (TI) to the sacculus rotundus (SR), across the ICJ and into the beginning of the large intestine at the cecum ampulla coli (AC). Orally propagating slow wave patterns in the SR did not entrain the TI. However, aborally propagating patterns from the TI were able to entrain the SR. Bioelectrical activity was recorded within the ICJ and AC, revealing complex interactions of slow waves, spike bursts, and bioelectrical quiescence. This suggests the involvement of myogenic coordination when regulating motility between the small and large intestines. Mean slow wave frequency between regions did not vary significantly (13.74-17.16 cycles/min). Slow waves in the SR propagated with significantly faster speeds (18.51 ± 1.57 mm/s) compared with the TI (14.05 ± 2.53 mm/s,iP/i= 0.0113) and AC (9.56 ± 1.56 mm/s,iP/i= 0.0001). Significantly higher amplitudes were observed in both the TI (0.28 ± 0.13 mV,iP/i= 0.0167) and SR (0.24 ± 0.08 mV,iP/i= 0.0159) within the small intestine compared with the large intestine AC (0.03 ± 0.01 mV). We hypothesize that orally propagating slow waves facilitate a motor-brake pattern in the SR to limit outflow into the ICJ, similar to those previously observed in other gastrointestinal regions.bNEWamp; NOTEWORTHY/bCompeting slow wave pacemakers were observed in the terminal ileum and sacculus rotundus. Prevalent oral propagation in the sacculus rotundus toward the terminal ileum potentially acts as a brake mechanism limiting outflow. Slow waves and periods of quiescence at the ileocecal junction suggest that activation may depend on the coregulatory flow and distention pathways. Slow waves and spike bursts in the cecum impart a role in the coordination of motility.

A handheld refractometer (HHR) is a versatile instrument in the chemistry lab or in the workplace. It is also inexpensive enough (

Swallowing is a vital function that serves to safely transport food and fluid to the stomach, while simultaneously protecting our airways. Evaluation of swallowing is important for the diagnosis and rehabilitation of individuals with dysphagia, a disorder of swallowing. Flexible high-density surface electromyography (HD sEMG) arrays were designed and fabricated to span the floor of mouth and neck muscles. These arrays were applied on 6 healthy participants over duplicate recording sessions. During each recording session, participants performed three different swallowing motor tasks. The HD sEMG signals were filtered and tasks extracted. For each task, the RMS amplitude was computed, visualized, and compared. Dynamic motor coordination was evident in the filtered signals traces, with different electrode locations showing unique temporal activations. The 2D topographical maps allowed the location of different RMS intensities to be visualized, revealing qualitatively similar patterns across participants and tasks. These motor task trends were also seen within RMS quantifications. The RMS metric across all participants identified significant differences between non-effortful 3 ml and effortful 3 ml swallow tasks ( p=0.006) and there was a minimal variation of 3.1±1.9 μV RMS for repeated recording sessions by each participant. The HD-sEMG array successfully recorded differences in muscle activations during swallowing and was able to discern between two different motor tasks. The arrays offers a spatially detailed non-invasive assessment of the neuromuscular performance of swallowing. Clinical Relevance- The utility of HD-sEMG arrays for evaluation of the muscles involved in swallowing could enable diagnosis and rehabilitation of individuals with dysphagia.

We report a simple means to build a model atomic force microscope (AFM) using 3D printing of thermoplastic materials that are commercially available. The model has many of the key parts of an actual AFM including a z-axis stage, an AFM head with a cantilever assembly, and a laser source that reflects off of the back of the cantilever. Using a magnet attached to the tip of the cantilever and a metal sample, this model AFM enables acquisition of force–distance profiles with characteristic snap-in, pull-off, separate, and contact regions. The model AFM was designed, printed, and used by first- and second-year undergraduate students. Through completion of this project, students learned scientific instrument design and construction via 3D printing and obtained first-hand practice in the measurement of force–distance profiles and the elastic constants of cantilevers. The open design of the model can easily accommodate additional capabilities in which students are interested, e.g., topographical scanning and using cantilevers made from different materials.

We report on the design of subwavelength grating metamaterial waveguides coated with tellurium oxide on a silicon-on-insulator platform. We discuss our design optimization that led to substantial improvements of modal overlap with the optically active cladding., 2021 Photonics North (PN), May 31 - June 2, 2021, Toronto, ON, Canada

Intestinal motility is coordinated by myogenic, neuronal and hormonal factors. Myogenic control of motility via bioelectric slow waves (SW) has been investigated using low-resolution and high-resolution (HR) electrical mapping techniques. Due to the highly conformable and irregular surface of the gut, suboptimal coverage of HR recordings may occur. In this study we designed and developed an inflatable cuff as a platform to apply even pressure across the intestinal surface to achieve consistent and reliable recordings. The inflatable cuff and a HR electrode array were applied in vivo to demonstrate the reliability of SW signal acquisition over a range of inflatable pressures (0 - 5 mm Hg). The frequency, amplitude, percentage of viable signals and signal to noise ratio metrics of the SW signals were computed and compared. Overall, with an increase in inflatable pressure from 0 to 5 mm Hg, the frequency did not change, but the amplitude of the SWs decreased from 0.10 to 0.07 mV. The noise levels were consistent across the range of inflatable pressure levels and the percentage of viable SW recordings improved significantly from 57% to 74% after application of 1 mm Hg of pressure. The inflatable and conformable cuff presented in this study provides a reliable platform for HR mapping of bioelectrical events in the intestines and other conformable organs.Clinical Relevance— This framework improves the quality and reliability of bioelectrical high-resolution recordings obtained from the small intestine. In the future, these recordings will improve our understanding of the pathophysiological mechanisms governing intestinal motility disorders and may provide clinicians with new strategies for diagnosis and treatment.

We report on the design, fabrication and characterization of subwavelength grating metamaterial waveguides coated with tellurium oxide. The structures are first fabricated using a standard CMOS compatible process on a silicon-on-insulator platform. Amorphous tellurium oxide top cladding material is then deposited via post-process RF magnetron sputtering. The photonic bandstructure is controlled by adjustment of the device geometry, opening a wide range of operating regimes, including subwavelength propagation, slow light and the photonic bandgap, for various wavelength bands within the 1550 nm telecommunications window. Propagation loss of 1.0 ± 0.1 dB/mm is reported for the tellurium oxide-cladded device, compared to 1.5 ± 0.1 dB/mm propagation loss reported for the silicon dioxide-cladded reference structure. This is the first time that a high-index (n > 2) oxide cladding has been demonstrated for subwavelength grating metamaterial waveguides, thus introducing a new material platform for on-chip integrated optics.

We report on a novel hybrid deposition technique to dope silicon-based materials with optically active elements in a plasma enhanced chemical vapor deposition (PECVD) process using a magnetron sputtering source. This approach is in contrast to traditional methods of rare-earth doping of PECVD films that utilise a metal organic precursor to introduce the rare earth species into the host matrix. We investigated the influence of the sputtering power applied to the rare earth metal target, in this case terbium, and the argon (Ar) partial pressure on the optical properties and composition of terbium-doped silicon oxide (SiOx:Tb3+) thin films. The film morphology was determined using high-resolution transmission electron microscopy, Rutherford backscattering spectrometry, and elastic recoil detection. We demonstrated that employing this novel technique provides a wider range of control of the doping level, yet delivers a similar rare earth (terbium) content to that which can be achieved using a traditional metal organic process. While the terbium concentration was strongly influenced by the sputtering power, it was only slightly affected by the Ar partial pressure. The refractive index was calculated from variable angle spectroscopic ellipsometry analysis and shows a direct relationship with the sputtering power whereas the film thickness shows an inverse relationship. The optically active Tb3+ ions were successfully excited within the silicon dioxide host matrix and the green Tb3+ emission was visible by the naked eye.

Cassini Synthetic Aperture Radar (SAR) images of Titan’s surface revealed river networks strikingly similar to those on Earth. However, Cassini SAR has low spatial resolution and image quality compared to data used to map channels on Earth, so traditional methods for characterizing river networks might not yield accurate results on Titan. We mapped terrestrial analog networks with varying resolutions and image qualities to determine which geomorphologic metrics were invariant with scale or resolution. We found that branching angle and drainage density varied significantly with image resolution, and we therefore expect the actual drainage density of Titan’s channel networks to be significantly higher than the values calculated from Cassini data. Calculated network geometry did not change predictably with resolution and would therefore not be an ideal metric for interpreting Titan’s channel networks. The measured channel width, basin length and width, and drainage area all behaved predictably as resolution varied, leading us to conclude that these metrics could be applied to Cassini data. We then mapped all observable fluvial features on Titan—excluding those in the highly incised labyrinth terrains—visible in the Cassini data set. In our new maps, we observe differences in basin shapes between Titan’s polar and equatorial regions and dichotomies in the relative channel density between the northern and southern midlatitudes and poles of Titan: channels are concentrated at the poles and southern midlatitudes. These patterns may reflect differences in bedrock material and/or different climate histories.

We report on low-temperature and low-pressure deposition conditions of 140 °C and 1.5 mTorr, respectively, to achieve high-optical quality silicon nitride thin films. We deposit the silicon nitride films using an electron cyclotron resonance plasma-enhanced chemical vapour deposition (ECR-PECVD) chamber with Ar-diluted SiH4, and N2 gas. Variable-angle spectroscopic ellipsometry was used to determine the thickness and refractive index of the silicon nitride films, which ranged from 300 to 650 nm and 1.8 to 2.1 at 638 nm, respectively. We used Rutherford backscattering spectrometry to determine the chemical composition of the films, including oxygen contamination, and elastic recoil detection to characterize the removal of hydrogen after annealing. The as-deposited films are found to have variable relative silicon and nitrogen compositions with significant oxygen content and hydrogen incorporation of 10–20 and 17–21%, respectively. Atomic force microscopy measurements show a decrease in root mean square roughness after annealing for a variety of films. Prism coupling measurements show losses as low as 1.3, 0.3 and 1.5 ± 0.1 dB/cm at 638, 980 and 1550 nm, respectively, without the need for post-process annealing. Based on this study, we find that the as-deposited ECR-PECVD SiOxNy:Hz films have a suitable thickness, refractive index and optical loss for their use in visible and near-infrared integrated photonic devices.

Coordinated contractions and motility patterns unique to each gastrointestinal organ facilitate the digestive process. These motor activities are coordinated by bioelectrical events, sensory and motor nerves, and hormones. The motility problems in the gastrointestinal tract known as functional gastrointestinal disorders (FGIDs) are generally caused by impaired neuromuscular activity and are highly prevalent. Their diagnosis is challenging as symptoms are often vague and difficult to localize. Therefore, the underlying pathophysiological factors remain unknown. However, there is an increasing level of research and clinical evidence suggesting a link between FGIDs and altered bioelectrical activity. In addition, electroceuticals (bioelectrical therapies to treat diseases) have recently gained significant interest. This paper gives an overview of bioelectrical signatures of gastrointestinal organs with normal and/or impaired motility patterns and bioelectrical therapies that have been developed for treating FGIDs. The existing research evidence suggests that bioelectrical activities could potentially help to identify the diverse etiologies of FGIDs and overcome the drawbacks of the current clinically adapted methods. Moreover, electroceuticals could potentially be effective in the treatment of FGIDs and replace the limited existing conventional therapies which often attempt to treat the symptoms rather than the underlying condition.

This work presents a lecture and lab series that focuses on teaching the concept of nanophytotoxicity to undergraduate students in a relatively simple experiment. In this experiment, students evaluated the phytotoxicity of engineered nanomaterials (ENMs) using mung beans (i.e., Vigna radiata) and industrially relevant, commercially available ENMs, silicon dioxide (SiO2) and zinc oxide (ZnO) nanoparticles (NPs). In comparison to the control system using solutions of Nanopure water, the growth of mung beans in solutions of ZnO NPs with a concentration of 20 mg/L was severely stunted, showing clear evidence of a high level of nanophytotoxicity. The growth of mung beans in solutions of SiO2 NPs with the same concentration was intermediate to, though statistically separate from, the aforementioned solutions, showing clear evidence of a lower level of nanophytotoxicity than for the ZnO NPs. The simplicity of the experiment and the clear phytotoxic results should make this experiment of interest to many types of...

We report low optical loss germanium oxide (GeO2) thin films which have been deposited by low pressure ion-assisted alternating current dual magnetron sputtering of germanium targets in an oxygen plasma environment. The germanium oxide films ranging from 0.7- to 1.0-µm-thick were fabricated at low temperature and high deposition rates of 6–38 nm/min on silicon and thermally oxidized silicon substrates. The refractive index of the films was determined through variable angle spectroscopic ellipsometry and found to be 1.6051 on average at a wavelength of 638 nm. The films were shown to be near stoichiometric through Rutherford backscattering spectroscopy analysis and displayed sub-nanometer roughness when measured with atomic force microscopy. High peak-to-valley uniformity on a 3-inch substrate with relative deviation of 0.8% was achieved. We characterized the attenuation of the GeO2 thin films from visible to near-infrared wavelengths and observed it to be as low as 0.1 dB/cm at 638 nm for deposition rates of 8 nm/min. This deposition technique provides complementary metal-oxide-semiconductor compatible GeO2 thin films suitable for integrated photonics applications and is promising for the fabrication of other dielectric waveguide materials.

Human cortical activity has been intensively examined at frequencies ranging from 0.5 Hz to several hundred Hz. Recent studies have, however, reported also infraslow fluctuations in neuronal population activity, magnitude of electroencephalographic oscillations, discrete sleep events, as well as in the occurrence of interictal events. Here we use direct current electroencephalography to demonstrate large-scale infraslow oscillations in the human cortex at frequencies ranging from 0.02 to 0.2 Hz. These oscillations, which are not detectable in conventional electroencephalography because of its limited recording bandwidth (typical lower limit 0.5 Hz), were observed in widespread cortical regions. Notably, the infraslow oscillations were strongly synchronized with faster activities, as well as with the interictal epileptic events and K complexes. Our findings suggest that the infraslow oscillations represent a slow, cyclic modulation of cortical gross excitability, providing also a putative mechanism for the as yet enigmatic aggravation of epileptic activity during sleep.

Purpose: EEG studies based on adult populations report interictal epileptiform discharges (EDS) favour the left hemisphere. It is not clear when favouring becomes apparent as similar paediatric studies have not been performed. Methods: The authors reviewed 1579 paediatric EEG interpretations for evidence of hemispheric favouring of focal epileptiform discharges. Analysis focused on first-time EEG results. Results: Right hemispheric favouring of interictal epileptiform discharges occurs in childhood, it remits around 5 years of age whereupon left-sided favouring occurs more frequently ( P =0.004, Fisher's Exact). Conclusion: Hemispheric vulnerabilities to interictal focal epileptiform activity may display discrete age-related favouring. These findings are discussed in context of normal hemispheric maturation.

A differential optical absorption spectrometer for measurements of low-level sulfur dioxide (SO2) emissions from vehicles in real time was developed and employed. With a time resolution of 3 s and an optical path length of 19.6 m, a minimum detection limit of 75 ppbv SO2 (three times the standard deviation) was achieved. The wavelength region covered, UVB, was chosen to include the major SO2 absorption feature at 300 nm, while avoiding wavelength regions in which other components of vehicle exhaust are known to absorb. However, formaldehyde was found to be present in vehicle exhaust in high enough concentrations to be a major interferent. The analysis software was modified to account for the formaldehyde interferent using a two-dimensional fitting routine. The application of the instrument to real vehicle exhaust demonstrated that it was capable of measuring the contribution to SO2 emissions from lubricant oil sulfur over the range of current and future oil sulfur levels.

Background: This study tested the idea that very slow EEG responses (direct current [DC] potential shifts) could be detected noninvasively during temporal lobe (TL) seizures, and that these shifts give lateralizing information consistent with that obtained by other methods. Methods: Seven patients with TL epilepsy (TLE) were recorded with scalp DC-EEG technique at bedside. All recordings were performed simultaneously with conventional EEG (scalp in five, and intracranially in two; two patients with scalp recordings were recorded intracranially later). Seizures in five patients originated in the mesial TL. Ictal DC shifts were evaluated by comparing them to the temporal evolution of ictal discharges, and by comparing the laterality of these shifts to the side of seizure onset defined by routine EEG and other presurgical diagnostic tests. Results: All seizures (35/35) were associated with negative DC shifts at temporal derivations (30 to 150 μV relative to vertex), beginning at the electrical seizure onset, and lasting for the whole seizure. In eight seizures (five patients) with documented mesial TL onset, the polarity of the DC shift was initially positive followed by a negative one after lateral spread of seizure activity. In all cases, the side of the EEG shift agreed with other diagnostic tests, and, at times, was more clearly lateralized than the conventional scalp EEG. Conclusions: DC-EEG recordings are practical and achievable at the bedside. Ictal DC shifts are consistently observed in scalp recordings in TL seizures, and reliably lateralize them. This method may hold promise in reducing the need for invasive monitoring in patients with TLE where other noninvasive tests are equivocal.

Rigid polyurethane foams were formed on rough zinc phosphate treated steel substrates. The interface between the two materials was investigated using knife peeling, immersion in a solvent which removes amorphous material predominantly, stud pull tests to observe bond failure, and X-ray scattering studies. There were three regions at the interface: an unbonded bare zinc phosphated surface, solid polyurethane areas where foaming did not occur, and foamed regions. These various interfacial regions result from temperature gradients during polymerization and foaming, and poor wetting of the substrate by the polymer. After immersion in a solvent, the solid polyurethane layer bonded to the substrate was completely removed, implying that this area only weakly adheres to the steel substrate. By contrast, the removal of the foamed area exhibited a well-ordered crystalline phase underneath polymer residues. In grazing angle X-ray scattering from the foamed region, a sharp peak from polyurethane crystallites was foun...

Hippocampal deafferentation has been proposed as a pathogenetic mechanism for neurofibrillary tangle (NFT) formation in human mesolimbocortical dementia. We previously developed a rodent model of hippocampal deafferentation involving bilateral destructive lesions of the ventrotegmental area (VTA), septum of the medial forebrain and entorhinal cortex combined with pharmacological inhibition of serotonin 5-HT2 and dopamine D1 receptors. Unexpectedly, we observed an alteration in phosphorylated neurofilament protein immunoreactivity and argyrophilia in magnocellular neurones of the red nucleus. Here, we determined the neuroanatomical, pharmacological and temporal requirements for this effect on red nucleus neurones. We found that abnormal phosphorylation and argyrophilia were critically dependent on bilateral destruction of the VTA and antagonism of 5-HT2 receptors. Although extensive neurofilament hyperphosphorylation and argyrophilia were observed in red nucleus magnocellular neurones within nine days of treatment, no NFTs were formed and these effects were transitory. Resolution of these cytoskeletal abnormalities was accompanied by increased expression of the calcium binding protein, parvalbumin, suggesting that alterations in intraneuronal calcium levels may modify the deafferentation response.

We read with concern the position statement1 and editorial2 on generic substitution of antiepileptic drugs (AEDs). The American Epilepsy Society and the Epilepsy Foundation are also studying generic substitution and legislation restricting generic prescription is being considered throughout the United States. These efforts are surprising since there is scant published evidence of problems with current generic AED formulations, and generic versions of many newer AEDs have yet to be released. While problems have been noted with older generic formulations of poorly water-soluble AEDs such as phenytoin, generic versions of newer, highly soluble AEDs such as gabapentin, zonisamide, lamotrigine, topiramate, and levetiracetam are unlikely to have similar problems.3 Nonetheless, hard evidence is absent. We feel that prospective, blinded, randomized trials—not anecdotal opinion surveys—are required to address a highly concrete, quantifiable subject: whether generic AEDs achieve significantly different serum levels than brand versions. Despite the paucity of data, legislation has been proposed in Washington State (HB 2123)4 among others, which would impede prescription of generic AEDs by requiring providers and patients to separately consent to their dispensing. This will diminish the use of generics by allowing patients to opt out of generic substitution when the prescription is filled, and by confronting providers with additional paperwork. These barriers to generic competition will only increase prescription drug costs, both for the patient who pays out of pocket and for third-party and government health care payers. This is not in the patient’s best interest. We also need to acknowledge the significant financial forces that may influence the debate. Brand name AEDs each generate hundreds of millions of dollars annually in revenue for the manufacturer, and this revenue typically drops by 80 to 90% in the first year after generic versions are introduced. Thus, the pharmaceutical industry has a vested interest in …

Wildland fires are expected to increase as a consequence of climate change forces and more data were needed to help facility managers carry out prescribed burns, especially for the burning of southwestern and southeastern wild land fuels. As a consequence, RC-1648 and RC-1649 projects were funded to provide new information on the properties of the fuels in the field and models for the burning rates using both field and laboratory data. The combined projects collected and analyzed the most comprehensive data for gaseous and particulate matter emissions from these sources. Further the use of continuous instruments allowed the direct measurement of the emission factors for gases and particulate matter as the burns transitioned from flaming to smoldering regimes. Included in the final report and about 20 published journal articles are new and improved emission factors for criteria pollutants, selected hazardous air pollutants and elemental factors in EPA's AP-42 format for wildfire for DoD facilities with southeastern and southwestern fuels. A key finding in the RC -1648 project was the discovery that the percentage of graphic carbon is related to the fire intensity and the emissions rates of black and brown carbon. The complicated EPA CMAQ model was compared to the BlueSky framework. The later appears to be more useful to local land managers in developing estimated smoke emissions from prescribed burns.

A generalized likelihood ratio test is developed for classification in two populations when one needs to control one of the probabilities of misclassification. The proposed classification procedure is constructed by applying the parametric bootstrap to the generalized likelihood ratio. There are known methods for controlling this misclassification probability for the case where normal distributions with the same covariance matrix are assumed. Our approach, however, can be applied to not only this case but to the case of normal distributions with different covariance matrices and the case of a mixture of discrete and continuous variables. The results given here do not depend on normality but can, in fact, be applied to any distribution for which the maximum likelihood estimates exist. We do, however, restrict our simulation of these results to the normal distribution if the variates are all continuous. Three cases are simulated: normal distributions with equal covariance matrix, normal distributions with unequal covariance matrices, and mixture of categorical and normal variables. An application to classifying seismic events is presented.

The prevalence of atypical (right, bilateral) speech lateralization is unknown in normal populations. The authors investigated this by studying people with normal developmental histories but a later, specific adult neurologic event leading to intractable epilepsy. Fifty of 836 people receiving intracarotid amobarbital procedures (IAPs) met criteria of normal neurologic histories through age 15 years, with later head trauma or cerebral infection as probable cause of subsequent epilepsy. All 50 patients had left hemispheric speech on IAP. Atypical speech lateralization is rare unless there is also a positive neurologic history.

The anionic polymerization of isoprene with n-butyl lithium and polar modifier such as TMEDA and tripiperdinophosphine oxide were studied and kinetic and reactor models are proposed for these systems. Reactor conversion, molecular weight distribution and polymer glass transition temperature had been calculated from the model and compared favorably to the actual data for various combinations of reactor systems and operating conditions. Simulations of the model can be used to design reactor systems and predict polymer properties of large-scale operations from results of small scale batch reactor runs.

In a closed basin, where runoff is not allowed to discharge outside the watershed, a systematic design of storm water routing with retention facility is necessary to manage the runoff. This article presents a successful design to route the excess runoff generated due to the change in land-cover from an 11.4 acre site in Tallahassee, Florida, USA. The site development involved conversion of a wooded area to an aquatics complex with pools, buildings, parking lots, and driveway access etc. creating 2.4 acre impervious area. A pond with adequate storage capacity was not feasible to construct within the site due to site constraints and high-cost. The runoff generated from the new impervious area was designed to route through the newly designed small onsite dry-detention pond and discharged to an existing offsite pond, located within a closed basin. The analysis showed successful design of an onsite pond that retains as much water as possible within the site and safely releasing excess volume downstream to the offsite pond. The results confirmed that the offsite pond in the closed basin can retain all runoff without any discharge and the two ponds in series can handle any extreme storm in an integrated manner.

The mechanism of action of zeolite A (ZA) on eggshell quality could be related either to its ion-exchange properties or to individual ZA elements (Al or Si). Two experiments were conducted to determine 1) whether any ZA passes through the digestive system in its original form; and 2) whether any Al and Si absorption occurs. In Experiment 1, unfed hens were intubated with either 0 or 5 g ZA at oviposition. In Experiment 2, fed and unfed hens were intubated at oviposition with 0, 1, or 2 g ZA. At the subsequent oviposition, liver and kidney tissues, excreta, urine, bile, and plasma were collected and analyzed for Al, Si, Na, K, and P. The results indicated that approximately 7% of the intubated ZA passed through the digestive system in its original form (Experiment 1). As the intubated level of ZA increased, excreta Al and Si (P < .0001), urine Si (P < .005), and urine Al (P < .07) also increased (Experiment 2). Aluminum recovery from excreta ranged from 75 to 93% of the quantity intubated in all treatments. Corresponding values of Si from excreta of unfed and fed hens ranged from 76 to 81% and 58 to 60%, respectively. The P content of excreta was not influenced by ZA. However, excreta P was greater (P < .0001) in unfed than in fed hens. Neither plasma electrolytes (Na, K, and P) nor Al or Si levels in either liver or kidney were influenced by ZA.(ABSTRACT TRUNCATED AT 250 WORDS)