Giant piezoelectricity on Si for hyperactive MEMS   总被引：1，自引：0，他引：1  

Baek SH  Park J  Kim DM  Aksyuk VA  Das RR  Bu SD  Felker DA  Lettieri J  Vaithyanathan V  Bharadwaja SS  Bassiri-Gharb N  Chen YB  Sun HP  Folkman CM  Jang HW  Kreft DJ  Streiffer SK  Ramesh R  Pan XQ  Trolier-McKinstry S  Schlom DG  Rzchowski MS  Blick RH  Eom CB 《Science (New York, N.Y.)》2011,334(6058):958-961

Microelectromechanical systems (MEMS) incorporating active piezoelectric layers offer integrated actuation, sensing, and transduction. The broad implementation of such active MEMS has long been constrained by the inability to integrate materials with giant piezoelectric response, such as Pb(Mg(1/3)Nb(2/3))O(3)-PbTiO(3) (PMN-PT). We synthesized high-quality PMN-PT epitaxial thin films on vicinal (001) Si wafers with the use of an epitaxial (001) SrTiO(3) template layer with superior piezoelectric coefficients (e(31,f) = -27 ± 3 coulombs per square meter) and figures of merit for piezoelectric energy-harvesting systems. We have incorporated these heterostructures into microcantilevers that are actuated with extremely low drive voltage due to thin-film piezoelectric properties that rival bulk PMN-PT single crystals. These epitaxial heterostructures exhibit very large electromechanical coupling for ultrasound medical imaging, microfluidic control, mechanical sensing, and energy harvesting.  相似文献   

Theaflavins depolymerize microtubule network through tubulin binding and cause apoptosis of cervical carcinoma HeLa cells     

Chakrabarty S  Das A  Bhattacharya A  Chakrabarti G 《Journal of agricultural and food chemistry》2011,59(5):2040-2048

Here we studied the antiproliferative activity of theaflavins in cervical carcinoma HeLa cells by investigating their effects on cellular microtubules and purified goat brain tubulin. Theaflavins inhibited proliferation of HeLa cells with IC(50) value of 110 ± 2.1 μg/mL (p = < 0.01), caused cell cycle arrest at G(2)/M phase and induced apoptosis with alteration of expression of pro- and antiapoptotic proteins. Along with these antiproliferative activities, theaflavins act as microtubule depolymerizers. Theaflavins disrupted the microtubule network accompanied by alteration of cellular morphology and also decreased the polymeric tubulin mass of the cells. The polymerization of cold treated depolymerized microtubules in HeLa cells was prevented in the presence of theaflavins. In vitro polymerization of purified tubulin into microtubules was also inhibited by theaflavins with an IC(50) value of 78 ± 2.43 μg/mL (P < 0.01). Thus, disruption of cellular microtubule network of HeLa cells through microtubule depolymerization may be one of the possible mechanisms of antiproliferative activity of theaflavins.  相似文献   

Studies on bacteriological quality of nainital lake water in different seasons     

Jyotsna Pande  S. M. Das  D. S. Misra 《Water, air, and soil pollution》1983,19(2):149-154

The total coliform and E. coli load of Nainital lake water in different seasons has been studied. The variation of these organisms with season, rainfall and human activities in the catchment area were observed.  相似文献   

Prioritisation of conservation areas in the Western Ghats, India     

Arundhati Das  Jagdish Krishnaswamy  Kamaljit S. Bawa  M.C. Kiran  N. Samba Kumar 《Biological conservation》2006,133(1):16-31

Areas of high conservation value were identified in the Western Ghats using a systematic conservation planning approach. Surrogates were chosen and assessed for effectiveness on the basis of spatial congruence using Pearson’s correlations and Mantel’s tests. The surrogates were, threatened and endemic plant and vertebrate species, unfragmented forest areas, dry forests, sub-regionally rare vegetation types, and a remotely sensed surrogate for unique evergreen ecosystems. At the scale of this analysis, amphibian richness was most highly correlated with overall threatened and endemic species richness, whereas mammals, especially wide-ranging species, were better at capturing overall animal and habitat diversity. There was a significant relationship between a remote sensing based habitat surrogate and endemic tree diversity and composition. None of the taxa or habitats served as a complete surrogate for the others. Sites were prioritised on the basis of their irreplaceability value using all five surrogates. Two alternative reserve networks are presented, one with minimal representation of surrogates, and the second with 3 occurrences of each species and 25% of each habitat type. These networks cover 8% and 29% of the region respectively. Seventy percent of the completely irreplaceable sites are outside the current protected area network. While the existing protected area network meets the minimal representation target for 88% of the species chosen in this study and all of the habitat surrogates, it is not representative with regard to amphibians, endemic tree species and small mammals. Much of the prioritised unprotected area is under reserve forests and can thus be incorporated into a wider network of conservation areas.  相似文献   

Insecticidal activity of Arum maculatum tuber lectin and its binding to the glycosylated insect gut receptors     

Majumder P  Mondal HA  Das S 《Journal of agricultural and food chemistry》2005,53(17):6725-6729

Mannose binding approximately 50 kDa homotetrameric lectin, purified from edible Arum maculatum tuber, was analyzed through SDS-PAGE and studied for its agglutination property using rabbit erythrocytes. Cross reactivity of the purified lectin was verified through western blot using Colocasia esculantum(Family, Araceae) tuber lectin antibody. The insecticidal activity of Arum maculatum tuber lectin (ATL) was tested against two economically important sucking pests, Lipaphis erysimi and Aphis craccivora, in an artificial diet. The LC(50) values for L. erysimi and A. craccivora were determined to be 21 microg/mL and 16 microg/mL, respectively. Addition of alpha-d-mannose in ATL-supplemented diet reduced the aphid mortality. Two major receptor proteins of ATL (approximately 40 kDa and approximately 35 kDa) were detected from the brush border membrane vesicle (BBMV) protein of L. erysimi and A. craccivora guts, respectively, using ligand-binding assay. Alpha-d-Mannose was found to be a deterrent to such binding of ATL to the BBMV receptors.  相似文献   

Stage Sensitivity of Mungbean (Vigna radiata L. Wilczek) to an Elevated Level of Carbon Dioxide     

M. Das  P. H. Zaidi  M. Pal  & U. K. Sengupta 《Journal of Agronomy and Crop Science》2002,188(4):219-224

An experiment was undertaken using open‐top chambers to study the effect of CO₂ enrichment on crop growth and to assess the variation related to the time of CO₂ exposure. In general, enriched CO₂ conditions (600 ± 50 p.p.m.) in the chamber positively affected the growth and development of mungbean (Vigna radiata), a short‐duration (60–65 days) summer pulse crop. However, there was significant variability in the effect of the crop stage/time of CO₂ exposure. It was observed that high CO₂ exposure at an early growth stage [0–20 days after germination (DAG)] had a larger effect than that at a later growth stage (21–40 DAG). The experiment also provided a means of assessing the short‐ and long‐term effects of elevated CO₂ on the carbon exchange rate at both stages of exposure. The study revealed that the sensitivity of plants to high CO₂ was more pronounced with respect to net photosynthetic rate. The overall photosynthetic activity gave greater growth and development of plants under high CO₂.  相似文献   

Inheritance of congenital cataracts and microphthalmia in the Miniature Schnauzer   总被引：1，自引：0，他引：1  

K N Gelatt  D A Samuelson  J E Bauer  N D Das  E D Wolf  K P Barrie  T L Andresen 《American journal of veterinary research》1983,44(6):1130-1132

Congenital cataracts and microphthalmia in the Miniature Schnauzer were inherited as an autosomal recessive trait. Eighteen matings of affected X affected Miniature Schnauzers resulted in 87 offspring with congenital cataracts and microphthalmia (49 males/38 females). Two matings of congenital cataractous and microphthalmic Miniature Schnauzers (2 females) X a normal Miniature Schnauzer (1 male) yielded 11 clinically normal Miniature Schnauzers (7 males/4 females). Eighteen matings of congenital cataractous and microphthalmic Miniature Schnauzers (6 males) X carrier Miniature Schnauzers (9 females) produced 81 offspring; 39 exhibited congenital cataracts and microphthalmia (20 males/19 females) and 42 had clinically normal eyes (17 males/25 females).  相似文献   

International society for horticultural science calendar of events 1979     

S. Rath  G.C. Das 《Scientia Horticulturae》1979,11(1):101-106

A study was made to induce flowering in an “off-year” in the strictly irregularly-bearing mango cultivar ‘Langra’. Cycocel 3000 mg/l on ringed shoots produced the largest number of flower panicles (62.3%), whereas the control recorded the lowest number (8%). MH-1500 mg/l with ringing reduced the length of the shoot, increased the diameter of the shoots, and greatly reduced the vegetative growth. All the treatments produced quite good percentages of flower buds in comparison to the control, and enhanced the flowering-time. With CEPA 400 mg/l the flowering-time was enhanced by 16 days.  相似文献   

Available Moisture in Relation to Water-stable Aggregates of Two Forest Soils     

A. Das  S. K. Gupta 《Journal of Agronomy and Crop Science》1987,159(1):66-70

Available moisture release characteristics for two well aggregated clayey forest soils of West Bengal (INDIA) were determined with respect to different-sized water-stable aggregates. In situ determination of higher range of available moisture differed appreciably from classic 1/3 bar moisture retention, for the soils. Release of moisture at lower tensions (0.33 > bar) were mainly governed by the inter-aggregate pore size distribution while that at higher tension chiefly attributed to the texture of aggregates i.e. the intra-aggregate pore size distribution. The difference in moisture releasing capacity particularly in the range 0.33—15.0 bar amongst different sized aggregates, was due mainly to varying amount of clay and organic carbon in different-sized aggregates.  相似文献   

Structure—activity relationships for some organotin molluscicides     

Peter J. Smith  Alan J. Crowe  V. G. Kumar Das  John Duncan 《Pest management science》1979,10(5):419-422

Bioassay data are reported for 12 organotin compounds, R₃SnX, against the adult snail, Biomphalaria glabrata, an intermediate host of schistosomiasis. The relationship between the molluscicidal activity and the nature of the R and X groups in the organotin compounds is discussed, as well as the possible mode of toxic action of these compounds.  相似文献