Molecules for converting sunlight into electricity     

Ravi Mosurkal 《Resonance》2001,6(10):76-86

The dream of generating electricity from sunlight in large scale at low cost may not be that far from reality in this century. Rapidly emerging solar energy technology using low cost dye sensitized photovoltaic cells on plastics would be a real boost for the third world countries. Though the conventional silicon solar cells are efficient in converting solar energy into electricity until now, the non conventional solar cells based on molecular photosensitization by colored materials in wide band gap semiconductors is a fast growing field of basic scientific and industrial research. Present state-of-the-art cells using molecular dyes shows energy conversion efficiencies of 10–11%. In this article, we present the concept of dye-sensitized photovoltaic (DSPV) cell and the progress in current research. The important contributions of molecular dyes that are used as photosensitizers in these photovoltaic or solar cells are also described.  相似文献   

Prostate specific antigen in patients of benign prostate hypertrophy and carcinoma prostate     

T. Malati  G. Rajani Kumari  P. V. L. N. Murthy  Ch. Ram Reddy  B. Surya Prakash 《Indian journal of clinical biochemistry : IJCB》2006,21(1):34-40

Prostate Specific Antigen (PSA) has emerged as the most applicable and important tumor marker for carcinoma prostate. In the present study PSA was determined in serum of healthy subjects, patients of benign prostate hypertrophy (BPH) and Carcinoma Prostate (Ca−P) to evaluate its diagnostic efficiency in day to day management of prostate cancer patients and in differentiating patients of early prostate cancer from those with BPH. Receiver operating characteristic curve (ROC) revealed 2 ng/ml and 10 ng/ml cut off serum PSA level for BPH and untreated carcinoma prostate patients (Ca−P). An extremely significant increase (P<0.0001) was observed in mean PSA concentration in BPH patients and adenocarcinoma prostate patients when compared to healthy males. Clinical relevance of PSA was highlighted by a case study of cancer patient prior to any therapy till death.  相似文献   

Revisiting Zhang’s scale of transactional distance: refinement and validation using structural equation modeling     

Ravi C. Paul  William Swart  Aixiu Monica Zhang  Kenneth R. MacLeod 《Distance Education》2015,36(3):364-382

Transactional distance has been defined as barriers to students’ engagement with learning in the online environment. This research updates Zhang’s (2003) scale of transactional distance, which quantified the extent of the barriers, in light of the massive changes in today’s web-based learning environment. The resulting revised scale of transactional distance (RSTD) is a parsimonious version with 12 elements (compared to 31 original) that measure the transactional distance between student and teacher, student and student, and student and content. The RSTD has excellent factorial validity and reliability, yields better fit statistics, and is easier and less time-consuming to apply. The transactional distance values are unique predictors of student satisfaction, which is correlated to learning and persistence (a major concern with massive open online courses). This information can form the basis for a systematic approach to improving the design of today’s contemporary open, flexible, distance education courses and thus serve as a valuable tool for researchers and educators alike.  相似文献   

Cortical network for reading linear words in an alphasyllabary     

Tanusree Das  Raju S. Bapi  Prakash Padakannaya  Nandini C. Singh 《Reading and writing》2011,24(6):697-707

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The forgotten promise of e-government maturity: Assessing responsiveness in the digital public sector     

Kim Normann Andersen  Rony Medaglia  Ravi Vatrapu  Helle Zinner Henriksen  Robin GauldAuthor vitae 《Government Information Quarterly》2011,28(4):439-445

Assessing e-government responsiveness is one of the major gaps in the currently dominant e-government maturity models. While we have a relatively large pool of models focusing on technological and organizational integration from a supply side perspective, measures of responsiveness of e-government systems from a user perspective are still lacking. Replicating a study from New Zealand and Australia, this study explores the response time and quality of e-mail response in Danish local and central governments (N = 175). Despite that Denmark is high ranking in international benchmark studies, we find that one third of central government agencies did not respond at all, and close to 80% of the ministries provided none or incomplete answers. Local government responds faster and provides answers that are more complete and accurate than those provided by central government. Implications for e-government are discussed.  相似文献   

Serum total PSA and free PSA in breast tumors     

Dash P  Pati S  Mangaraj M  Sahu PK  Mohapatra PC 《Indian journal of clinical biochemistry : IJCB》2011,26(2):182-186

Now a days measurement of molecular forms of PSA has gained importance in clinical practice. Several studies have demonstrated the production of PSA in female tissues, such as breast. The present piece of work has been undertaken with an objective to estimate the relative proportion of the molecular forms of PSA in serum along with serum testosterone in benign and malignant breast tumor cases and to analyze their association with the severity of the disease process 34 malignant and 26 benign breast disease cases along with 33 healthy controls of same age group were enrolled in this study for evaluation. Serum testosterone was measured by ELISA, whereas serum total PSA (TPSA) and free PSA (FPSA) were estimated by electrochemiluminescence immunoassay. A significant rise of fasting plasma glucose along with prominent dyslipidemia was observed in breast tumor cases. Marked rise in serum testosterone as well as TPSA and FPSA was documented in both benign and malignant breast tumor cases. Serum testosterone revealed a significant positive association with both TPSA and FPSA pointing towards an etiological association between them. However, surgical removal of tumor mass resulted in a marked decline of presurgical value of both TPSA and FPSA with a non-significant fall in serum testosterone revealing tumor tissue as the source of FPSA and TPSA. Thus, estimation of PSA provides prognostic information that may assist in future treatment.  相似文献   

Effects of roller burnishing process parameters on surface roughness of A356/5%SIC composite using response surface methodology     

Shashi Prakash Dwivedi Satpal Sharma Raghvendra Kumar Mishra 《上海大学学报(英文版)》2014,(4):303-317

In this study, a simple roller burnishing tool was made to operate burnishing processes on A356/5%SIC metal matrix composite fabricated by electromagnetic stir casting under different parameters. The effects of burnishing speed, burnishing force and number of burnishing passes on the surface roughness and tribological properties were measured. Scanning electron microscopy （SEM） graphs of the machined surface with PCD （insert-10） tool and roller burnished surface with tungsten carbide （WC） roller were taken into consider- ation to observe the surface finish of metal matrix composites. The mechanical properties （tensile strength, hardness, duc- tility） of A356/5%SIC metal matrix composites were studied for both unburnished samples and burnished samples. The results revealed that the roller burnished samples of A356/ 5%SIC led to the improvement in tensile strength, hardness and ductility. In order to find out the effects of roller bur- nishing process parameters on the surface roughness of A356/ 5%SIC metal matrix composite, response surface methodol- ogy （RSM） （Box-Behnken design） was used and a prediction model was developed relevant to average surface roughness using experimental data. In the range of process parameters, the result shows that roller burnishing speed increases, and surface roughness decreases, but on the other hand roller burnishing force and number of passes increase, and surface roughness increases. Optimum values of burnishing speed （1.5 m/s）, burnishing force （50 N） and number of passes （2） during roller burnishing of A356/5%SIC metal matrix com- posite to minimize the surface roughness （predicted 1.232 μm） have been found out. There was only 5.03% error in the experimental and modeled results of surface roughness.  相似文献   

End-user satisfaction of technology-enabled assessment in higher education: A coping theory perspective     

Pillai  K. R.  Upadhyaya  Pallavi  Prakash  Ashish Viswanath  Ramaprasad  Badrinarayan Srirangam  Mukesh  H. V.  Pai  Yogesh 《Education and Information Technologies》2021,26(4):3677-3698

Education and Information Technologies - The current study examines students’ coping process of a forced technological intervention in academic outcome assessment in a higher education...  相似文献   

Comparative account of serum lipids,lipoproteins and apolipoprotein-B in patients of coronary artery disease     

Ritu Sharma  Mridula Mahajan  Ravi Kant 《Indian journal of clinical biochemistry : IJCB》2004,19(1):10-13

Serum total lipids (cholesterol and triglyceride), lipoproteins (VLDL, LDL and HDL) and Apolipoprotein-B levels of normal healthy individuals (n=25) and coronary artery disease patients (n=25) were estimated. The objective of the present study was to ascertain the role of apo-B in causation and inheritance of coronary artery disease. It was observed that on an average serum total cholesterol and triglyceride more than 200 mg/dl bring the individuals to a risk of coronary artery disease (CAD) irrespective of the age. CAD patients achieved this value at an early age (35–45 years). Similarly VLDL and LDL levels were found to be significantly raised in CAD patients when compared to that of age matched normal individuals, with patients achieving risk values at an early age. HDL levels were found to be significantly lower in CAD patients as compared to normal individuals. Serum apo-B levels were significantly raised in CAD patients as compared to age matched normal individuals. Patients with positive family history of CAD had raised serum apo-B levels than those having negative family history. A positive coefficient of correlation was observed between serum apo-B and LDL levels suggesting that more the number of Apo-B particles, more will be the synthesis of atherogenic particle (LDL). Patients with negative family history had serum apo-B levels closer to those of normal individuals and in these individuals HDL levels were found to be significantly lowered, suggesting that loss of scavenger role of HDL could be the risk factor responsible for the causation of CAD in these patients, with negative family history of coronary artery disease.  相似文献   

Nature watch     

Ishwar Prakash 《Resonance》1997,2(10):54-61

Gerbils are rodents with a long hairy tail terminating in a tassel of hair.Gerbillus, Tatera andMeriones are the genera found in India. These rodent genera of Sahara-Tharian region differ from each other in their origin and dispersal. Since a large number of species of the genusGerbillus are found in the African continent, it is conjectured that Africa was the centre of their differentiation. However,Tatera is found only south of Sahara.Meriones of Asiatic origin which crossed over to northern Africa across the Sinai desert is now found in Egypt, Libya, Algeria, Tunisia, Morocco and several parts of Asia.  相似文献