10,245 research outputs found
Comparison of calculated and experimental cascade performance for controlled-diffusion compressor stator blading
The mid-span section of a previously reported controlled-diffusion compressor stator has been experimentally evaluated in cascade. Measurements are taken over a range of incidence angles for blade chord Reynolds numbers from 470,000 to 690,000. Blade chord length is 12.7 cm, aspect ratio is 2.0, and solidity is 1.67. Measurements include conventional cascade performance parameters as well as blade surface pressures. Computations are made for the inviscid flow field, surface boundary layers, and loss for several of the blade inlet angle conditions, are compared against corresponding data
Static performance of a 13.97 cm (5.5 inch) diameter model VTOL lift fan
A tip-turbine-driven fan of the type currently being used in wind tunnel tests of VTOL lift fan models was tested. Values of thrust, weight flow, exit total and static pressure, exit swirl angle, and turbine temperature drop were measured as a function of fan speed for several inlet and exit configurations. A standard fan performance map was also obtained
Electrokinetic measurements of membrane capacitance and conductance for pancreatic -cells
Characterization of rat gastric myogenic contractions and modulation by oxytocin and arginine-vasopressin.
BACKGROUND: and purpose: Interstitial cells of Cajal generate slow wave gastric electrical activity, initiating spontaneous muscle contractions. This becomes dysrhythmic during nausea when [Arg8]-vasopressin (AVP) is also released. In human stomach AVP increased spontaneous contraction activity and muscle tone, not neuronally-mediated contractions. Rodents cannot vomit, releasing the related hormone, oxytocin (OT) instead. We hypothesised that rat stomach would behave differently. EXPERIMENTAL APPROACH: Spontaneous and electrically-evoked (EFS) contractions were measured in rat forestomach and antrum circular muscle. Custom software defined spontaneous contractions by analysing eight motility parameters. RESULTS: The forestomach was quiescent. Irregular antrum contractions became regular adjacent to the pylorus (1.7 ± 0.4 mN; 1.2 ± 0.1 contractions/min, n = 12). These were unaffected by tetrodotoxin (10-6 M), atropine (10-6 M) and L-NAME (3 × 10-4 M). In both regions, AVP (pEC50∼9.0) and OT (∼0.5 log10-unit less potent) caused contraction (greater in antrum), competitively antagonized by, respectively, SR49059 (pKB∼9.5) and L371257 (pKB∼9.0), reduced by tetrodotoxin but unaffected by atropine. In the antrum, AVP and OT (∼2 log10-units less potent/efficacious) regularized and increased spontaneous contraction amplitude, frequency, rates of contraction/decay. In both regions, EFS-evoked contractions, abolished by atropine/tetrodotoxin, were reduced by AVP and OT, with AVP more potent and efficacious, particularly in forestomach. CONCLUSION: Irregular spontaneous contractions of gastric antrum suggest variable ICC-muscle coupling. AVP and less potently, OT, enhanced frequency and force of contractions via V1A and OT receptors. Compared with human, differences in contraction regularity, potency and ability of AVP/OT to affect neuronal function suggests caution when using rat stomach to model ICC functions and nauseagenic stimuli
Development and application of a self-referencing glucose microsensor for the measurement of glucose consumption by pancreatic ?-cells
Glucose gradients generated by an artificial source and ?-cells were measured using an enzyme-based glucose microsensor, 8-?m tip diameter, as a self-referencing electrode. The technique is based on a difference measurement between two locations in a gradient and thus allows us to obtain real-time flux values with minimal impact of sensor drift or noise. Flux values were derived by incorporation of the measured differential current into Fick's first equation. In an artificial glucose gradient, a flux detection limit of 8.2 ± 0.4 pmol·cm-2·s-1 (mean ± SEM, n = 7) with a sensor sensitivity of 7.0 ± 0.4 pA/mM (mean ± SEM, n = 16) was demonstrated. Under biological conditions, the glucose sensor showed no oxygen dependence with 5 mM glucose in the bulk medium. The addition of catalase to the bulk medium was shown to ameliorate surface-dependent flux distortion close to specimens, suggesting an underlying local accumulation of hydrogen peroxide. Glucose flux from ?-cell clusters, measured in the presence of 5 mM glucose, was 61.7 ± 9.5 fmol·nL-1·s-1 (mean ± SEM, n = 9) and could be pharmacologically modulated. Glucose consumption in response to FCCP (1 ?M) transiently increased, subsequently decreasing to below basal by 93 ± 16 and 56 ± 6%, respectively (mean ± SEM, n = 5). Consumption was decreased after the application of 10 ?M rotenone by 74 ± 5% (mean ± SEM, n = 4). These results demonstrate that an enzyme-based amperometric microsensor can be applied in the self-referencing mode. Further, in obtaining glucose flux measurements from small clusters of cells, these are the first recordings of the real-time dynamic of glucose movements in a biological microenvironment. <br/
Design and performance of a fixed, nonaccelerating, guide vane cascade that operates over an inlet flow angle range of 60 deg
A unique set of wind tunnel guide vanes are designed with an inverse design code and analyzed with a panel method and an integral boundary layer code developed at the NASA Lewis Research Center. The fixed guide vanes, 80 feet long with 6-foot chord length, were designed for the NASA Ames 40 x 80/80 x 120 ft Wind Tunnel. Low subsonic flow is accepted over a 60 deg range of inlet angle from either the 40 x 80 leg or the 80 x 120 leg of the wind tunnel, and directed axially into the main leg of the tunnel where drive fans are located. Experimental tests of 1/10-scale models were conducted to verify design calculations
PENGEMBANGAN PRODUKSI MINUMAN RUMPUT LAUT Euchema cottonii DI KELURAHAN MALALAYANG DUA KECAMATAN MALALAYANG, KOTA MANADO
Sasaran program ini berlokasi di Kelurahan Malalayang Dua Kecamatan Malalayang Kota Manado, yang secara geografis sangat strategis untuk dikembangkan industri pengolahan minuman rumput laut. Kelurahan ini merupakan daerah wisata kuliner, dimana terdapat banyak pengusaha makanan dan minuman. Sulawesi Utara, merupakan penghasil rumput laut yang besar, dengan demikian ketersediaan bahan baku mudah diperoleh dan memadai untuk pengolahan secara industri. Pengolahan minuman rumput laut yang terdiri dari sirup, sari dan serbuk instan, sangat mudah serta pemasarannya tidak sukar, dapat dijangkau oleh masyarakat kelas ekonomi atas maupun bawah. Tujuan program ini yaitu pengembangan lapangan usaha baru untuk meningkatkan ekonomi masyarakat serta meningkatkan nilai jual dan ekonomi rumput laut. Target khusus program IbM ini yaitu 1. Memproduksi minuman rumput laut memenuhi syarat sanitasi dan higienis, dikemas dan dilabel dengan baik/menarik; 2. Mengembangkan usaha industri minuman sirup rumput laut. Adapun metode pelaksanaan yang disepakati dengan mitra yaitu: 1. Masalah produksi minuman sirup rumput laut, pemasaran produk dan keuangan; 2. Metode untuk menyelesaikan masalah dengan penyuluhan, pelatihan, pendampingan dan evaluasi; 3. Prosedur kerja untuk menyelesaikan masalah melalui survei, penyuluhan, pelatihan, pendampingan, evaluasi, pelaporan dan jurnal
- …