Direct Air Flow Research Articles

Lactoferrin-loaded contact lenses: eye protection against oxidative stress.

Tear fluid contains antioxidative compounds, vitamin C, glutathione, superoxide dismutase, and lactoferrin (LF), which protect the corneal epithelium from the effects of ultraviolet irradiation, direct airflow, and chemical agents. However, these natural defenses against oxidative stress can decrease, favoring the development of anterior eye disorders, such as keratoconus, dry eye, and Sjögren syndrome. LF is an iron-binding glycoprotein, present in mammalian secretions such as tears and milk, endowed with different physiological functions such as antimicrobial, antiviral, and antioxidant activities. In this work, we studied the capability of different soft contact lenses to adsorb and release LF to restore cellular viability in oxidative stress conditions. Three types of contact lenses (filcon V, galyfilcon A, and filcon IB) were loaded with LF and then incubated with TsA or human corneal epithelial primary cells. After oxidative stress induction with 250 μM or 125 μM H2O2, cell viability was evaluated. Data showed that the highest quantity of LF loaded in contact lenses was between 61 μg (for filcon V) and 39 μg (for filcon IB); the release was between 49% and 100% of protein adsorbed. LF released from contact lenses maintained its antioxidant activity at least for 24 hours and was able to protect human epithelial cells from the detrimental effects of oxidative stress. These results demonstrate that LF-loaded contact lenses could represent a new therapeutic approach to treat ocular surface pathologies characterized by high levels of oxidative stress.

Uncinate Preserving Procedures: A Leading Step toward Conservation in Functional Endoscopic Sinus Surgery

ABSTRACT Uncinate process is thought to be having role in controlling airflow dynamics at the osteo meatal complex. Excision of uncinate process during traditional functional endoscopic sinus surgery (FESS) affects these airflow patterns increasing the flow in the sinuses in inspiration and decreasing it during expiration. Conventional way of performing a FESS always includes uncinectomy. However, preservation of uncinate process during surgery leads to the protection of the opened sinuses and avoid the attack of direct airflow to the sinus along with maintaining the normal nasal drainage from the sinus cavities. There is no clear evidence or consensus in the issue and regarding the feasibility of successful access in the ethmoids and sphenoids and beyond by preserving this immensely important land mark. In this study, we have tried to see that whether it is feasible to conserve uncinate as a future eland mark and preserve more normal nasal physiology compared with the resection of uncinate process. How to cite this article Gupta AK, Patro SK. Uncinate Preserving Procedures: A Leading Step toward Conservation in Functional Endoscopic Sinus Surgery. Clin Rhinol An Int J 2015;8(1):12-14.

Survey of Airflow around Multiple Buildings

This survey paper offers a review of past and present studies related to air flow around multiple building configurations to achieve energy savings and thermal comfort in hot climate regions in the presence of increased urbanization. The purpose of this review paper is to provide guidelines based on previous studies for the successful design of group housing in a hot and arid climate such as Egypt to improve air flow around multiple rows of buildings. This study presents several types of courtyard designs inside houses that provide direct air flow at windward sides inside compactly planned buildings. Next, air flow is described around one individual building and two buildings that have a passage between them. Furthermore, air flow around buildings is discussed to include several rows of buildings that range from rectangular linear to square shapes with flat and jack roofs, where the main goal is to achieve appropriate wind velocity at inlet surfaces, especially at the second and the third rows of buildings, and to avoid turbulence zones caused by wind around building. Finally, the effect of topography and urban mass on global wind velocity at the city scale is discussed.

Improvised arrangement of aerosol delivery to the ventilator dependent patient.

Sir, The patients supported by invasive mechanical ventilation (IMV) often require aerosol therapy for bronchodilators and inhaled corticosteroids. Mucolytics, antibiotics and other medications can also be given by this method.[1] Aerosol therapy is indicated in these patients for management of asthma, bronchospasm, increased airway resistance, intrinsic positive end-expiratory pressure, difficult to wean, and ventilator dependent patients. Aerosol therapy helps in reducing work of breathing by decreasing pulmonary dynamic hyperinflation and resistance of the respiratory system.[2] Effective delivery of aerosol to the lungs depends on formulation of drug, aerosol generator, and technique of administration. Various devices are used to generate aerosol, but pressurized metered-dose inhaler (pMDI) and nebulizers are the most commonly used in patients supported by IMV. The commonly used nebulizers are the jet and the ultrasonic devices. Vibrating mesh nebulizers and intratracheal nebulizing catheters are newer aerosol generating devices. These devices are connected to the inspiratory limb of the ventilator circuit by specific adaptors attached to the artificial airway. Several ventilator parameters also affect the effective delivery of aerosol to the patient. pMDI require a specific adaptor, a spacer and synchronization with ventilator for effective delivery of aerosol. If properly administered pMDI and nebulizers are equally effective in delivery of aerosol therapy to the mechanically ventilated patients although using nebulizers is the common practice. Jet nebulizers use a jet of compressed air or oxygen, while ultrasonic nebulizers use piezo-electric crystals vibrations to produce aerosol. New vibrating mesh nebulizers use a vibrating mesh or plate with multiple apertures to generate aerosol. Jet nebulizers are cost-effective and easy to use and adding a reservoir between jet nebulizer and endotracheal tube increases aerosol delivery. Some new generation ventilators have an in-built mechanism for supporting the jet or ultrasonic nebulizers. These ventilators synchronize inspiratory flow and volume to activate the jet nebulizer intermittently during inspiration.[3] Over a period of time, these compatible jet nebulizers tend to be damaged or lost. Many ventilators are not compatible with jet nebulizers or newer aerosol therapy devices. In these situations, often a jet nebulizer operated by compressed oxygen from wall system or cylinder, is attached to the inspiratory limb of breathing circuit. A minimum flow of 6-8 L is required to generate the aerosol. The volume added by this method can affect ventilator parameters and can be very harmful, especially to the pediatric patients who have small lung volumes. Self-inflating manual resuscitator is a breathing system that uses nonrebreathing unidirectional valves. A pressure limiting device is present near inspiratory valve to prevent barotrauma in all infant/child and some adult manual resuscitators. There is a connection port to attach a reservoir bag at the bag inlet.[4] In this improvized arrangement, a T-adaptor with jet nebulizer assembly is attached to the above mentioned connection port [Figure 1]. A one-way valve [Direction, Figure 1] is attached to the free end of the T-adaptor to prevent aerosol loss and direct airflow to the bag inlet when it is re-expanding. Presence of resuscitation bag next to the jet nebulizer and addition of 3-4 mL of normal saline to the drug can help in effective delivery of aerosol. The tidal and minute volumes can be controlled manually to deliver aerosol safely to the ventilator dependent patients where compatible aerosol device is not available. Figure 1 Improvized arrangement

D122 排熱利用直接接触型空気吹出式融雪システムの実証試験(OS-11:凝固・融解を伴う伝熱現象とその応用(1))

We report on a direct contact airflow type snowmelt system using exhaust heat, which flows air quasi-uniformly from the surface of the water-and-air permeable concrete block or surface. Two different types of the system have been verified as a reliable snowmelt system through experimental study. One is unit block type, and the other is construction site deposit type. The unit block type has hollow plastic cubic structure under the water-and-air permeable concrete block. The heat source is residential exhausted heat and delivered to the snowmelt site by electric fan. The construction site deposit type has perforated tube under the water-and-air permeable concrete surface. The heat source is taken from sewer manhole inflow which hot spring waste water comes in. Both of the system showed capable performances as snowmelt system at the test site installed in Hokkaido district.

MEASURING THE LUNG FUNCTION CONTINUOUSLY AND UNOBTRUSIVELY

Background and Aims: The conventional pulmonary function tests (PFTs) require respiratory maneuvers like forced maximal expiration, and only give snap shot information of the lung function. Our aim is to devise methodology for continuous unobtrusive assessment of the lung function using a wearable impedance pneumography (IP) system. Methods: IP is based on the knowledge that the electrical impedance of the thorax is proportional to the lung volume. Thus, variation in the lung volume can be assessed by placing two or more measurement electrodes on the surface of the body to measure the impedance variations. Furthermore, the obtained signal can be used to produce diagnostic tidal breathing flowvolume loops. The shape of these loops change in a characteristic way when an airway obstruction occurs or is relieved (Beydon et al. 2011). Results: We have conducted multiple measurements on healthy subjects and patients with obstructive airway diseases, assessing the agreement between the IP and a direct mouth airflow measurement. Thanks to our research on electrode locations and signal processing techniques, we have been able to produce highly accurate pulmonary flow-volume loops regardless of the subject body posture or presence of an obstructive airway disease. We also have produced a wearable cell phone size 24h IP recording device. Conclusions: IP is accurate enough to produce diagnostic pulmonary flow-volume loops. It does not require any direct connection with the airways nor any proactivity from the measurement subject, unlike the conventional PFTs. This potentially enables continuous, long-term estimation of changes in lung function due to external agents and obstructive diseases like asthma. In combination with personal exposure monitors, IP could be used to assess the immediate real-time effects of air pollution on the lung function. This would be especially beneficial for preschool children and infants with whom the conventional PFTs cannot be used at all.

Experimental study of a novel piezoelectric proton exchange membrane fuel cell with nozzle and diffuser

The newly designed proton exchange membrane fuel cell with a piezoelectric actuation structure, called a PZT-PEMFC, can force air into an air-breathing PEMFC system. Previous studies indicated the PZT-PEMFC may solve the water-flooding problem and improve cell performance. In this experimental study, a PZT-PEMFC with nozzle and diffuser, PZT-PEMFC-ND, is built to verify the previous theoretical study. This innovative design may direct air flow into the cathode channel through the diffuser and prevent air backflow without valves. The performance test includes an analysis of PZT vibration frequencies, cell operation temperatures, gravity effect, and designs of the nozzle and diffuser. The optimal operating temperature for the PZT-PEMFC-ND is 323 K to avoid the risk of higher temperatures drying out the membrane electrode assembly (MEA). The optimal vibration frequency of the PZT-PEMFC-ND is 180 Hz, which may pump in enough air and solve the water-flooding problem in the cathode channel. This study also concludes that the innovative design of the PZT-PEMFC-ND, may reach the performance of an open cathode stack configuration, 0.18 W cm −2, without an external air supply device.

An electromagnetic energy scavenger from direct airflow

This paper presents two types of electromagnetic power generators exploiting direct conversion of airflow into mechanical vibration: (1) a windbelt-based vibratory linear energy scavenger targeting strong airflows and (2) a Helmholtz-resonator-based generator capable of scavenging energy from weaker airflows, i.e. environmental airflows. Both devices consist of two tightly coupled parts: a mechanical resonator, which produces high-frequency mechanical oscillation from quasi-constant airflow, and a permanent magnet/coil system, which generates electrical power from the resonator's motion. The proposed energy scavengers obviate the typically required matching of the resonant frequencies of the scavenger and the ambient energy sources it taps. This enables a device that is simpler, smaller and higher-frequency than the previously reported resonant power generator. The windbelt-based energy scavenger demonstrated a peak-to-peak output voltage of 81 mV at 0.53 kHz, from an input pressure of 50 kPa. The Helmholtz-resonator-based energy scavenger achieved a peak-to-peak output voltage of 4 mV at 1.4 kHz, from an input pressure of 0.2 kPa, which is equivalent to 5 m s−1 (10 mph) of wind velocity.

Could rice be used as an anticaking agent in table salt?

The aim of the study was to examine whether powdered rice could be used as an anticaking agent in table salt. Salts free from anticaking food additives were selected and powdered rice was added at different concentrations (0%, 1%, 2%, 5%, 10% and 20%). The samples were placed away from direct light and airflow, and left exposed in the laboratory at room temperature and below 30% humidity. The weight of the samples was measured using an electronic laboratory balance and recorded daily for 4 days. At the end of the experiment, all the samples were dried at 105°C in order to determine exact dryness. All the salt samples containing powdered rice lost weight (0.56±0.08%), while the other salt samples free of powdered rice gained weight (10.31±0.63%) (P<0.001). A statistically significant difference was found between the first two (1% and 2%) and last three concentrations (5%, 10% and 20%) (P<0.001). Adding powdered rice to salt as an anticaking agent during salt manufacturing at a concentration of 1% could take the place of other anticaking food additives used in table salt production.

The structure of vocal sounds produced with the mouth closed or with the mouth open in treefrogs

Frogs and toads mostly call with their mouths shut, unlike many other vertebrates. Sound is generated when air crosses the larynx, but there is no direct airflow to the external environment and radiation occurs at the skin. This study directly compares the acoustic output obtained from euthanized frogs with the mouth open against the output obtained with the mouth closed during activation of the larynx by airflow. With the mouth closed, the vocal sac was inflated and the acoustic energy was concentrated in the same harmonics as in the advertisement call, whereas with the mouth open, energy was spread in a wide range of harmonics. The acoustic output at the dominant frequency was more intense with the mouth closed than with the mouth open. More sound was radiated through the vocal sac and head than through the rest of the body. The spectral differences between open and closed mouth treatments matched the differences observed between natural advertisement calls, produced with the mouth closed, and distress calls, produced with the mouth open. By calling with the mouth closed, treefrogs can potentially produce advertisement calls with the energy concentrated in a narrower frequency range than with the mouth open.

Measuring Ventilation Rates in Dairy Buildings

Knowledge of ventilation rates in dairy buildings is essential for determining indoorair quality and for estimating green house gases and particle emissions. Two new methods for estimating ventilation rates are introduced for situations where air velocities atventilation inlets and outlets are tedious or impossible to measure. The first method is applicable to buildings whose ventilation can be stopped or closed totally. The second method is useful in naturally ventilated buildings with large openings and high ventilation rates where spatial gas concentrations are heterogeneously distributed. In addition, traditional heat balance, moisture balance, carbon dioxide balance and direct airflow measurements for ventilation estimation are used. Confirmation experiments were performed to evaluate the different methods. Good agreement was found between heat, moisture and carbon dioxide balances. Direct velocity measurement for ventilation rate estimation was found to be impractical for naturally ventilated buildings. The two introduced methods were found to be simple and adaptable for estimating ventilation rates in dairy buildings.

The Determination of Changes in Body Heat Content during Exercise Using Calorimetry and Thermometry

Following the onset of exercise there is a sudden increase in metabolic heat production that cannot be initially offset by the body's heat loss mechanisms. During this thermal imbalance a change in body heat content (ΔHb) occurs. The only way the value for ΔHb can be truly determined is by performing simultaneous direct measurements of the rates of heat production and heat loss. There are several calorimetric methods that can be used to quantify these values. The most accurate and simple method for measuring the rate of heat production is by separately calculating the energy released from the oxidation of fats and carbohydrates using indirect calorimetry, while direct air flow calorimetry provides the most accurate and responsive measurement of total body heat loss. Thermometry is often used as a surrogate for calorimetry by estimating mean body temperature and subsequently deriving a value for ΔHb. The most common thermometry approach, the 2-compartment model of “core” and “shell” temperature, has been demonstrated to greatly underestimate ΔHb. The inclusion of a third compartment representing the thermal influences of muscle tissue has been demonstrated to provide a better thermometric estimation of ΔHb; however this requires the invasive measurement of intramuscular temperature. A modified 2-compartment thermometry model incorporating an “adjustment factor” correcting for the underestimation of the traditional model for ΔHb appears to be the most practical alternative. Further research is required to develop thermometry model for the better estimation of ΔHb under various conditions.

Magnetic Anomalies on the Tree Trunks

Magnetic measurements of soil and tree bark adjacent to a busy highway revealed a significant variation in the concentration of magnetic particles with distance from the highway. Further more, forest-facing tree-bark contains significantly more magnetic particles than road-facing tree-bark. Magnetic particles were detected both on the bark of the maple trees and in the first centimeter of the soil cover (O/A horizon). Stability of saturation isothermal magnetization (SIRM) and hysteresis parameters of the soil indicates the presence of single domain (SD/PSD) magnetic carriers. Measurements of the tree bark hysteresis parameters and SIRM detect a significant lower coercivity component that we interpret to be an indication of more abundant pseudo-single domain (PSD) type magnetic grains. Magnetic measurements around the perimeters of eight tree trunks reveal magnetic carriers whose distribution is antipodal to the source direction (highway). We interpret our observation by adopting an air circulation model, where suspended PSD/SD particles are carried in the air stream. The air stream from the heavy traffic lowers the amount of moisture on the tree trunk surfaces facing the highway and thus reduces an adhesive potential on this side. Therefore, more particles can stay on the moist side of the trunk protected from the direct airflow.

Investigation of two mercury vapor collection techniques

Objectives: The purpose of this investigation was to develop and test two in vitro mercury vapor collection techniques: a closed bottle technique (CB) and an intraoral flow (IOF) technique. Methods: Amalgam samples were prepared in acrylic first molars (#30) with standardized Class I preparations. In the CB technique, samples were placed in either a 25, 100 or 500 ml bottle (n=5). Vapor was analyzed with the Jerome M-411 using a syringe method over a 7 day period. In the IOF technique an impression of the lower right quadrant of a Typodont was taken with PVS impression material leaving a 5 mm space over #30. Samples were analyzed with the Jerome M-411 connected to the impression tray via tygon tubing at the buccal surface. Average mercury vapor release rates and standard deviations were calculated for each method. Data were analyzed by two-way ANOVA followed by Tukey HSD pairwise analysis for significant findings (α=0.05). Results: Both techniques indicated mercury vapor release was dependent on volume. The largest bottle, 500 ml, yielded a significantly greater (p≤0.00) amount of mercury vapor within the CB systems. In the IOF technique, the addition of air flow over the restoration demonstrated a significant increase (p≤0.05) in mercury vapor released compared to the sealed IOF technique. Significance: A method for mercury vapor analysis was developed for possible intraoral application. The IOF method with direct air flow removes possible saturation effects found in a CB system, while limiting external variables, which may contribute to errors associated with in vivo measurements.

An actively cold wind

The air-conditioning of buildings consumes vast amounts of power. Why not use wind for the purpose, not to power a generator but directly? The design concerned involves buildings with subtle shapes to direct air flow, and banks of internal heat pipes for 'regenerative cooling'.

Water Regulated Air Flow Controller for Permeability Measurements

Stored agricultural commodities can often be characterised as porous media. Transport processes in the pile are largely influenced by the air flow in the pores. This research is concerned with the design of a water regulated air flow controller and testing of its operation under conditions of laminar and nearly laminar flows. Using this controller and a pressure difference sensor one can measure air permeability. Moist wheat straw was used as the test sample. Forchheimer's relation explained very well our measured pressure differences (r2=0.994-0.999). Also the comparison with measurements using a direct air flow controller gave good results.

Active Vibration Control in Microgravity Environment

The low gravity environment of the Space Station is suitable for experiments or manufacturing processes which require near zero-g. Such experiments are packaged to fit into rack-mounted modules approximately 106.7 cm (42 in.) wide × 190.5 cm (75 in.) high × 76.2 cm (30 in.) deep. The mean acceleration level of the Space Station is expected to be on the order of 10−6 g (9.81 × 10−6 m/s2). This steady state acceleration is a superposition of aerodynamic drag, centripetal forces, and the gravitational attraction of the earth and of the moon. Excitations such as crew activity or rotating unbalance of nearby equipment can cause momentary disturbances to the vibration-sensitive payload which degrade the microgravity environment and compromise the validity of the experiment or process. Isolation of the vibration-sensitive payload from structure-borne excitation is achieved by allowing the payload to float freely within an enclosed space. Displacement-sensitive transducers indicate relative drift between the payload and the surrounding structure. Small air jets fixed to the structure direct air flow to impinge on the payload. This thrust force keeps the payload centered within the enclosed space. The mass flow rate of the air jets is controlled such that the resultant acceleration of the payload is less than a criterion of 10−5 g. It is expected that any power or fluid lines that connect the experiment to the Space Station structure can be designed such that their transmitted vibration levels are within the criterion. An experiment has been fabricated to test the validity of the active control process and to verify the flow and control parameters identified in a theoretical model. Zero-g is approximated in the horizontal plane using a low-friction air-bearing table. An analog control system has been designed to activate calibrated air jets when displacement of the test mass is sensed. The experiment demonstrates that the air jet control system introduces an effective damping factor to control oscillatory response. The amount of damping as well as the flow parameters, such as pressure drop across the valve and flow rate of air, are verified by the analytical model.

Pressure and temperature equalization at 200-km altitude

Atmospheric pressure at 200 km must be nearly constant over the entire earth as a result of large-scale air motions which can occur in the ionosphere. In the lower atmosphere, adjacent areas of high and low pressure can exist without annihilation by pressure equalization; direct air flow from high to low pressure does not occur, because balanced circulations develop in which inertial forces (centrifugal and Coriolis) balance the pressure forces and prevent equalization. At altitudes near 200 km, viscous forces prevent the balanced circulations from occurring, so pressure equalization can proceed rapidly. The heat transport associated with the air motion is large and tends to bring about temperature equalization also. At still higher altitudes, the heat content and the pressure forces are smaller but the viscous forces for a given velocity shear remain unchanged, making possible the existence of pronounced high-pressure areas in regions of local heating. The conclusion reached in this study does not permit one to accept the frequently held concept that the polar or auroral zone ionosphere is much warmer than the equatorial ionosphere with pressures at 200 km several times larger in the polar regions (e.g., at Churchill, Canada) than at temperate and low altitudes (e.g., at White Sands, New Mexico).

Engineering Features of the Union Oil-Shale Retort

Abstract The retorting of shale requires an operation combining very good heat and fuel economy with low capital investment. In order to meet these demands the Union Oil Company developed its novel underfeed retorting method, which was publicly demonstrated in 1950 in a 50-ton per day unit. The retorting unit employs countercurrent flow of shale and air in a kiln utilizing bottom feed of solids. Ash and clinkers are removed overhead, and the oil drained from the bottom of the unit is cooled by countercurrent heat exchange with the incoming shale. No water is required for process operation. Movement of the shale through this unit is effected by a hydraulically operated underfeed mechanism. The shale kiln employs an external retorting section with cowling to direct air flow over the fins and to control shell temperature. Unlike conventional retorts, fusion of ash is not considered a problem in the operation of the Union retort since specially designed sodium-filled plows carry out a scraping action in the plastic ash-fusion zone, maintaining uniform bed porosity and size range of the discharged ash. It has been estimated that a typical commercial shale mine can produce approximately 20,000 tons per day of shale. The shale-retorting plant designed to handle this production would employ a battery of retorts, each having a capacity of 1000 tons per day, and centralized gas-handling and hydraulic power-supply systems.