Gain Measurements Research Articles

The corrosion behaviours of plasma-sprayed Fe-based amorphous coatings

ABSTRACTFe-based amorphous coatings are increasingly recognised as promising candidates for the protection of coal-fired boilers against corrosion. The present study prepared Fe-based amorphous coatings on a T91 substrate by plasma spraying technology. The corrosion behaviour of the coating in hot Na2SO4 + K2SO4 salts at 700°C was investigated, and measurements of the mean mass gain were performed after each cycle to establish the hot corrosion kinetics of the coatings using the thermogravimetric technique. The coated specimens, especially specimens with 380-μm-thick coatings, exhibited lower mean gain rates at all operating cycles as compared to the uncoated T91 samples. The highest hot corrosion resistance was a result of the amorphous composite microstructure and high Cr and Ni elemental contents, which contributed to the formation of the protective oxides of chromium and nickel such as Cr2O3, NiO and NiCr2O4.

Growth performance and rumen development in Malabari kids reared under different production systems.

In order to investigate the effect of rearing systems on growth and rumen development in Malabari male kids, 14 pre-weaned Malabari male kids of uniform morphological characters were randomly divided into two equal groups as T1 and T2. Both the groups were reared intensively for 12weeks whereby kids under T1 group were allowed to suckle their dams and provided green grass ad libitum. The kids under T2 were weaned at the age of 7days and provided formulated semi-solid broiler goat concentrate diet through the feeding bottle and were not offered any grass/roughage. Parameters like live weight gain, daily weight gain and body measurements were studied to evaluate the growth performance. However, gastrointestinal tract morphometric studies and qualitative morphological analysis of rumen papillae were undertaken to measure the rumen development. The daily weight gain of kids under T2 was significantly (P ≤ 0.01) higher than the daily weight gain of kids under T1. Also, the body measurements like height at withers, heart girth and body length were significantly (P ≤ 0.01) higher in T2 than in T1. The rumen and abomasum were comparatively more developed in T2 than in T1. The morphology of rumen papillae in both groups was different in size, shape and colour. The length, width, density and surface area of rumen papillae among kids in T2 were significantly (P ≤ 0.01) higher than those kids in T1. The results of the present study indicated that the feeding of semi-solid broiler goat concentrate diet improved growth performance and early rumen development in kids.

Breath-holding as a means to estimate the loop gain contribution to obstructive sleep apnoea.

A hypersensitive ventilatory control system or elevated "loop gain" during sleep is a primary phenotypic trait causing obstructive sleep apnoea (OSA). Despite the multitude of methods available to assess the anatomical contributions to OSA during wakefulness in the clinical setting (e.g. neck circumference, pharyngometry, Mallampati score), it is currently not possible to recognize elevated loop gain in patients in this context. Loop gain during sleep can now be recognized using simplified testing during wakefulness, specifically in the form of a reduced maximal breath-hold duration, or a larger ventilatory response to voluntary 20-second breath-holds. We consider that easy breath-holding manoeuvres will enable daytime recognition of a high loop gain in OSA for more personalized intervention. Increased "loop gain" of the ventilatory control system promotes obstructive sleep apnoea (OSA) in some patients and offers an avenue for more personalized treatment, yet diagnostic tools for directly measuring loop gain in the clinical setting are lacking. Here we test the hypothesis that elevated loop gain during sleep can be recognized using voluntary breath-hold manoeuvres during wakefulness. Twenty individuals (10 OSA, 10 controls) participated in a single overnight study with voluntary breath-holding manoeuvres performed during wakefulness. We assessed (1) maximal breath-hold duration, and (2) the ventilatory response to 20s breath-holds. For comparison, gold standard loop gain values were obtained during non-rapid eye movement (non-REM) sleep using the ventilatory response to 20s pulses of hypoxic-hypercapnic gas (6% CO2 -14% O2 , mimicking apnoea). Continuous positive airway pressure (CPAP) was used to maintain airway patency during sleep. Additional measurements included gold standard loop gain measurement during wakefulness and steady-state loop gain measurement during sleep using CPAP dial-ups. Higher loop gain during sleep was associated with (1) a shorter maximal breath-hold duration (r2 =0.49, P<0.001), and (2) a larger ventilatory response to 20s breath-holds during wakefulness (second breath; r2 =0.50, P<0.001); together these factors combine to predict high loop gain (receiver operating characteristic area-under-curve: 92%). Gold standard loop gain values were remarkably similar during wake and non-REM sleep. The results show that elevated loop gain during sleep can be identified using simple breath-holding manoeuvres performed during wakefulness. This may have implications for personalizing OSA treatment.

Study of composite-based natural fibers and renewable polymers, using bacteria to ameliorate the fiber/matrix interface

In this paper, bacteria belonging to the species Acetobacter xylinum were used to modify the surface of natural fibers by depositing nanosized bacterial cellulose around natural fibers which enhances their adhesion to renewable polymers. Single fiber tensile test was used in order to determine their mechanical properties and surface. The practical adhesion between the modified fibers and the renewable polymers cellulose acetate butyrate is quantified using the single fiber pullout test. Simple weight gain measurements before and after the modification show that about 4 and 6% bacterial cellulose adheres to the fibers as a result of the bacterial modification procedure. Scanning electron microscopy micrographs confirm the presence of attached bacterial cellulose on the surfaces of natural fibers.

Single Stage C-Band Erbium-Doped Fiber Amplifier (EDFA) Development and Performance Evaluation

In this work, a single-stage C-band erbium-doped fiber amplifier (EDFA) has been constructed and characterized. Gain (G) and noise figure (NF) measurements collected for the C-band EDFA as a function of wavelength (1528.8 to 1562.3 nm) and laser pump powers are discussed. Further, the EDFA conversion efficiency (CE) as a function of laser pump powers is presented. Simplified mathematical expressions for the EDFA gain, NF, and CE are provided. The C-band EDFA signal gain remained flat in the spectral region 1539 to 1562 nm. Moreover, the C-band EDFA NF increased with wavelength and decreased with the 1480 nm laser pump powers. Additionally, the C-band EDFA maximum achieved conversion efficiency and signal gain is 22.64% at P1=19.49 mW and 22.6 dB at 1531.1 nm, respectively.

EFFECT OF HEMODIALYSIS PATIENTSˊ KNOWLEDGE RELATED TO TYPES OF FOOD RICH FLUID ON INTERDIALYTIC WEIGHT GAIN AMONG HEMODIALYSIS PATIENTS

Despite recent advances in knowledge and improvements in the technology of the hemodialysis, the prognosis of patients receiving hemodialysis (HD) remains poor due to in insufficient knowledge about nutrition which result in interdialytic weight gain. Education enables hemodialysis patients overcome interdialytic weight gain, correct the nutritional habit, improve knowledge, and awareness. Aim of the study: to evaluate effect of hemodialysis patientsˊ knowledge related to types of food rich fluid on interdialytic weight gain among hemodialysis patients. Method: quasi experimental study design was used. Setting: New General Mansoura Hospital. Purposive sample of this study composed of 70 adult hemodialysis patients who met inclusion criteria included in this study. Tools: two tools used in this study, hemodialysis patients’ knowledge questionnaire about types of food rich fluid & interdialytic weight gain measurement. Results: the result revealed significant improvement in hemodialysis patients’ knowledge related to types of foods rich fluid which was poor (mean ± SD = 2.17± 2.25) during pre test, and good (mean ± SD = 6.78± 2.24) during poet test. There was significant reduction of interdialytic weight gain. Conclusion: increase hemodialysis patients knowledge about types of foods rich fluid has a positive effect on reduction interdialytic weight gain.

Pregnancy Weight Gain Before Diagnosis and Risk of Preeclampsia: A Population-Based Cohort Study in Nulliparous Women.

Weight gain in early pregnancy may influence a woman's risk of developing preeclampsia. However, the consequences of weight gain throughout pregnancy up to the diagnosis of preeclampsia are unknown. The aim of this study was to determine whether pregnancy weight gain before the diagnosis of preeclampsia is associated with increased risks of preeclampsia (overall and by preeclampsia subtype). The study population included nulliparous pregnant women in the Swedish counties of Gotland and Stockholm, 2008 to 2013, stratified by early pregnancy body mass index category. Electronic medical records were linked with population inpatient and outpatient records to establish date of preeclampsia diagnosis (classified as any, early preterm <34 weeks, late preterm 34-36 weeks, or term ≥37 weeks). Antenatal weight gain measurements were standardized into gestational age-specific z scores. Among 62 705 nulliparous women, 2770 (4.4%) developed preeclampsia. Odds of preeclampsia increased by ≈60% with every 1 z score increase in pregnancy weight gain among normal weight and overweight women and by 20% among obese women. High pregnancy weight gain was more strongly associated with term preeclampsia than early preterm preeclampsia (eg, 64% versus 43% increased odds per 1 z score difference in weight gain in normal weight women, and 30% versus 0% in obese women, respectively). By 25 weeks, the weight gain of women who subsequently developed preeclampsia was significantly higher than women who did not (eg, 0.43 kg in normal weight women). In conclusion, high pregnancy weight gain before diagnosis increases the risk of preeclampsia in nulliparous women and is more strongly associated with later-onset preeclampsia than early-onset preeclampsia.

A simpler reference antenna gain measurement method

AbstractA simpler reference antenna gain measurement method, involving only 2 antennas—the test antenna and a reference antenna—is considered in this communication. It is shown that using this method, which can facilitate quick measurements, the gain of the test antenna can be measured nearly as accurately as through conventional measurement methods, including the 2‐antenna method. Careful gain measurements are done to this end by performing the Vector Network Analyzer's full 2 port calibration between the antenna under test and transmit end cables. The measured gain values using the proposed method are compared with the established gain measurement methods to prove the methodology. Though this possibility appears to be known to some antenna engineers, a demonstration has not yet been reported to the best of the authors’ knowledge. This communication presents such a demonstration.

Oxidation resistance of uncoated & detonation -gun sprayed WC-12Co and Ni-20Cr coatings on T-22 boiler steel at 900°C

Oxidation is the major degradation problem in aircraft, marine, coal fired boilers, factories, and sand-bar gas turbines. It is due to the usage of variety of fuels coupled with elevated working temperatures, which dominances to the degradation in all the applications. In the present investigation oxidation behavior of uncoated and detonation Gun sprayed WC-12Co and Ni-20Cr coatings on T-22 boiler steel has been investigated at 900°C in Silicon wire tube furnace for total duration of 50 cycles under cyclic condition, each cycle consisted of keeping the samples for 60 minutes at 900°C temperature followed by 20 minutes cooling at room temperature. Oxidation kinetics of uncoated and coated sample has been established with the help of weight gain measurements. The exposed samples were characterized by scanning electron microscopy/energy dispersive spectroscopy (SEM&EDS).The Ni-20Cr coating, with morphological observations was found to be more protective than uncoated and WC-12Co coated on T-22 boiler steel.

Miniaturized and high-performance RF packages with ultra-thin glass substrates

Advanced RF packages are demonstrate with active (low-noise amplifier, RF switch) and passive integration in ultra-thin 3D glass packages with miniaturization and enhanced performance. The novelty of this RF packages is three-fold: 1) Ultra-thin 100 μm glass, 2) Double-side thinfilm RF circuits interconnected with Through-Package Vias (TPVs), and 3) Direct assembly of the glass-core package to the board with Land Grid Array (LGA) connections. An innovative double-via process, starting from prefabricated vias in bare glass, polymer filling and via drilling, is utilized for a robust and high-yield substrate fabrication process. Scalable and low-cost panel laminate processes are utilized to form the RF circuits on the build-up layers. The performance benefits are demonstrated through interconnect loss, impedance match, electrical gain and noise figure measurements. Compared to existing RF substrates, the glass substrates show 2.5X miniaturization in substrate thickness with extensibility to thinner substrates.

Cochlear amplification and tuning depend on the cellular arrangement within the organ of Corti

The field of cochlear mechanics has been undergoing a revolution due to recent findings made possible by advancements in measurement techniques. While it has long been assumed that basilar-membrane (BM) motion is the most important determinant of sound transduction by the inner hair cells (IHCs), it turns out that other parts of the sensory epithelium closer to the IHCs, such as the reticular lamina (RL), move with significantly greater amplitude for weaker sounds. It has not been established how these findings are related to the complex cytoarchitecture of the organ of Corti between the BM and RL, which is composed of a lattice of asymmetric Y-shaped elements, each consisting of a basally slanted outer hair cell (OHC), an apically slanted phalangeal process (PhP), and a supporting Deiters' cell (DC). Here, a computational model of the mouse cochlea supports the hypothesis that the OHC micromotors require this Y-shaped geometry for their contribution to the exquisite sensitivity and frequency selectivity of the mammalian cochlea. By varying only the OHC gain parameter, the model can reproduce measurements of BM and RL gain and tuning for a variety of input sound levels. Malformations such as reversing the orientations of the OHCs and PhPs or removing the PhPs altogether greatly reduce the effectiveness of the OHC motors. These results imply that the DCs and PhPs must be properly accounted for in emerging OHC regeneration therapies.

Preparation, structure, and properties of an AlCrMoNbZr high-entropy alloy coating for accident-tolerant fuel cladding

A nearly equal molar ratio AlCrMoNbZr high-entropy alloy (HEA) coating was deposited on N36 zirconium alloy substrates using magnetron co-sputtering technology to enhance the corrosion resistance of light water reactor (LWR) fuel cladding. The microstructure, mechanical properties, surface wettability and corrosion resistance of the AlCrMoNbZr coating were systematically investigated. The X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses showed that the AlCrMoNbZr HEA coating contained a composite of amorphous and bcc-structured nanocrystals. A nanoindentation test revealed that the coating had a high hardness of 11.8 GPa, and a scratch test indicated that the coating well adhered to the N36 substrate. The contact angle test showed that the static contact angle was 109°, which indicated the good hydrophobic property of the coating. The corrosion measurement showed that the AlCrMoNbZr coating remained effective after it was immersed in static pure water at 360 °C and 18.7 MPa for 30 days, and no N36 substrate oxides formed, which indicated a superior corrosion resistance. Furthermore, the corrosion behaviour of the coating was discussed. The weight gain measurement (8.8 mg/dm2 weight gain) proved that the coating experienced an oxidation process, and during the process, protective Nb2Zr6O17, ZrO2 and Cr2O3 formed on the surface of the coating. Hence, the AlCrMoNbZr HEA coating is a potential candidate material for accident-tolerant fuel (ATF) coatings.

Ventilatory control sensitivity in patients with obstructive sleep apnea is sleep stage dependent.

The severity of obstructive sleep apnea (OSA) is known to vary according to sleep stage; however, the pathophysiology responsible for this robust observation is incompletely understood. The objective of the present work was to examine how ventilatory control system sensitivity (i.e. loop gain) varies during sleep in patients with OSA. Loop gain was estimated using signals collected from standard diagnostic polysomnographic recordings performed in 44 patients with OSA. Loop gain measurements associated with nonrapid eye movement (NREM) stage 2 (N2), stage 3 (N3), and REM sleep were calculated and compared. The sleep period was also split into three equal duration tertiles to investigate how loop gain changes over the course of sleep. Loop gain was significantly lower (i.e. ventilatory control more stable) in REM (Mean ± SEM: 0.51 ± 0.04) compared with N2 sleep (0.63 ± 0.04; p = 0.001). Differences in loop gain between REM and N3 (p = 0.095), and N2 and N3 (p = 0.247) sleep were not significant. Furthermore, N2 loop gain was significantly lower in the first third (0.57 ± 0.03) of the sleep period compared with later second (0.64 ± 0.03, p = 0.012) and third (0.64 ± 0.03, p = 0.015) tertiles. REM loop gain also tended to increase across the night; however, this trend was not statistically significant [F(2, 12) = 3.49, p = 0.09]. These data suggest that loop gain varies between REM and NREM sleep and modestly increases over the course of sleep. Lower loop gain in REM is unlikely to contribute to the worsened OSA severity typically observed in REM sleep, but may explain the reduced propensity for central sleep apnea in this sleep stage.

Development of Ultra-high Purity (UHP) Fe-Based Alloys with High Creep and Oxidation Resistance for A-USC Technology

The design of ultra-high purity (UHP) Fe-based model alloys for advanced ultra-supercritical (A-USC) technology is attempted in this work. Creep testing has been performed in air at 700 °C and a stress level of 150 MPa. Analysis of the fracture surface and cross section of the crept specimen was performed. To evaluate the oxidation resistance in A-USC conditions, oxidation testing was performed in supercritical water (SCW) at 700 °C and 25 MPa. Weight gain (WG) measurements and meticulous characterization of the oxide scale were carried out. Based on thermodynamics and density functional theory calculations, some reactive elements in the Fe-Cr-Ni system were designated to promote precipitation strengthening and to improve the hydrogen-accelerated oxidation resistance. The addition of a 2 wt pct Mo into Fe-22Cr-22Ni-0.6Nb wt pct-based matrix did not significantly improve the creep resistance. The addition of 0.26 wt pct Zr coupled with cold working was effective for improving creep properties. The Mo-modified model alloy showed almost the same WG value as SUS310, while the Zr-modified alloy showed a higher WG value. Meanwhile, a Cr-enriched continuous oxide layer was formed at the oxidation front of the Zr-modified alloy and SUS310S after exposure to SCW conditions.

Thin $\text{Al}_{\mathbf{1{-}}{\boldsymbol x}}$ Ga$_{\boldsymbol{x}}$As $_{\mathbf{0.56}}$Sb $_{\mathbf{0.44}}$ Diodes With Low Excess Noise

Thin avalanche layers have been adopted to achieve low excess noise and high-gain bandwidth products in InP and InAlAs avalanche photodiodes. In this paper, we report the excess noise characterization in a series of $\text{Al}_{\mathbf{1{-}}{\boldsymbol x}}$ Ga $_{\boldsymbol{x}}$ As $_{\mathbf{0.56}}$ Sb $_{\mathbf{0.44}}$ ( $x\,= \,0,\,0.05$ , 0.1, 0.15) diodes with avalanche layer thickness of 110–116 nm. These alloys, lattice matched to InP, showed lower excess noise than InP and InAlAs. Dark current, most probably originating from surface leakage, was observed to be lower in composition with higher Ga concentration. Avalanche gain and excess noise measurements using lasers of 543 and 633 nm wavelengths indicated that at a given electric field, the electron ionization coefficient is larger than the hole ionization coefficient. Using the 543 nm laser, low excess noise data corresponding to an effective ionization coefficient ratio of $k\,= \,0.1$ in the conventional excess noise theory was measured in $\text{Al}_{\mathbf{1{-}}{\boldsymbol x}}$ Ga $_{\boldsymbol{x}}$ As $_{\mathbf{0.56}}$ Sb $_{\mathbf{0.44}}$ ( $x\,= \,0.05$ , 0.1, 0.15), although pure electron injection was not achieved. Our results demonstrated the potential of using $\text{Al}_{\mathbf{1{-}}{\boldsymbol x}}$ Ga $_{\boldsymbol{x}}$ As $_{\mathbf{0.56}}$ Sb $_{\mathbf{0.44}}$ ( $x\,= \,0.05$ , 0.1, 0.15) as replacement for InP and InAlAs for high speed and low excess noise avalanche photodiodes. The data reported in this paper is available from the ORDA digital repository ( https://doi.org/10.15131/shef.data.5155822 ).

Corrosion performance of Cr3C2-NiCr+0.2%Zr coated super alloys under actual medical waste incinerator environment

Incineration techniques are widely used to dispose of various types of waste which lead to formation of very corrosive environment. Such corrosive environment leads to the degradation of the alloys used in these areas. To obviate this problem, zirconium modified Cr3C2-(NiCr) coating powder has been deposited on three superalloys namely Superni 718, Superni 600 and Superco 605 using Detonation gun technique. Corrosion test was conducted in actual medical waste incinerator environment. The samples were hung inside the secondary chamber operated at 1050°C for 1000h under cyclic condition. Corrosion kinetics was monitored using the weight gain measurements and thickness loss. Corrosion products were characterized using scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction technique. It was observed that coating is found to be successful in impeding the corrosion problem in superalloys.

Dependence of hydrogen-absorption and -desorption characteristics on density of lithium–zirconium oxides exposed in air at room temperature

The dependence of the hydrogen (H)-absorption and -desorption characteristics of air-exposed Li2ZrO3 samples at room temperature on Li2ZrO3 densities of 2.53–3.78 g/cm3, related to the surface area, and the most stable trapping sites of H were investigated using weight gain measurement (WGM), elastic recoil detection (ERD), Fourier-transform infrared (FT-IR) spectroscopy, thermal desorption spectroscopy (TDS), gas chromatography (GC), and first-principles calculations. The WGM, ERD, and FT-IR spectra revealed that the H concentration in Li2ZrO3 increased with increasing air exposure time and relative humidity and decreasing density by splitting water (H2O). The TDS and GC analyses revealed that hydrogen molecules (H2), as well as H2O, were released from the air-exposed Li2ZrO3 at annealing temperatures less than 323 K. In addition, it was found by using a density functional theory (DFT) code that H atoms dissociated from H2O preferred to occupy oxygen (O) substitutional sites in Li2ZrO3.

Enhancement of mass transport in fuel cells using three-dimensional graphene foam as flow field

Graphene foam is a three-dimensional graphene-based material with interconnected macropores and it combines the advantage of graphene and structural characteristics of metal foam. Various kinds of metal foam have been developed as flow fields because their high porosity distributes reactants in an entire area and removes generated water. However, metal foam is highly susceptible to corrosion under the operating conditions of polymer-electrolyte-membrane fuel cells. In this work, we proposed using graphene foam as a flow field to investigate its effect on enhancing mass transport of reactants and products. Single-cell tests of the graphene-foam flow field showed the enhancement of mass transport, which led to increased performance at high current densities. Measurements of the oxygen gain (i.e., the difference in voltage under O2 and air atmospheres), electrochemical impedance spectra, and simulation results also revealed that the graphene-foam membrane-electrode assembly (MEA) exhibited lower mass-transport resistance than a conventional MEA because graphene foam is advantageous for the mass transport of reactants and water.

Study on growth traits at weaning and yearling stages of indigenous and F1 crossbred buffalo in Bangladesh

This study was planned to clarify the variation of body weight and average daily gain traits in both indigenous and F1 crossbreed (Local×Mediterranean) buffalo at weaning (sixth month) and yearling stages (twelfth month). Data were collected from 33 indigenous and 35 F1 crossbred buffalo progeny during the period of 2011 to 2014 with intensive management system at Research and Development farm of Lal Teer Livestock Limited in Bangladesh. The gathered data were analyzed using general linear model (GLM) and independent sample t test. The effect of parity, sex, season and breeding year on body weight and average daily gain were observed where significant values found in breeding period (p &lt;0.01) of crossbred buffalo for body weight. It might be the reason of crossbreeding to indigenous buffalo cows using imported semen with better genetic merit. The parity (p &lt;0.05), season (p &lt;0.05) and breeding period (p &lt;0.01) were also significant for average daily gain measurement which suggesting environmental adaptability beside additive genetic effects. Body weights were measured at weaning and yearling stages for both local (113 to 195 kg) and F1 crossbred (144 to 220 kg) buffalo progeny to screen the elite offspring for the Genetic Farm and Bull station. Similarly, average daily gain observed 469 to 457 g and 600 to 506 g at the previously mentioned two stages for both local and F1 buffalos, respectively. It was observed that studied traits were comparatively better in F1 buffalo progeny than indigenous. The comparison of average daily weight gains between indigenous and F1 buffalos at weaning and yearling periods showed significant differences for body weight (p &lt;0.001) and average daily gain (p &lt;0.05), respectively. It is concluded that genetic gain might be possible in local buffalo population by grading up process which could switch the traditional buffalo rearing to commercial level as well as meeting the nutritional demand of country people.Asian J. Med. Biol. Res. December 2017, 3(4): 499-503

EDFA Wavelength Dependent Gain Spectrum Measurement Using Weak Optical Probe Sampling

Wavelength dependent gain is a critical parameter in erbium-doped fiber amplifiers and is the primary determinant of the channel power divergence and excursions in optical transmission systems, each of which varies with channel loading in wavelength-division-multiplexed (WDM) systems. In an optical transmission system, measurements of the wavelength dependent gain between two locations can be used to obtain estimates of optical power excursions that occur in optical circuit switching. Non-intrusive sampling of just 10% of the WDM channel positions using weak probe signals achieves less than 0.15 dB error for the gain spectrum estimation of the amplifier with 5 dB tilt. In a two-span node-to-node network with a 3 dB peak-to-peak channel power difference, the weak probe approach further shows to provide less than 0.2 dB error in optical channel power excursion prediction for changes in channel loading.