Enantioselective assembly of multi-layer 3D chirality     

Guanzhao Wu  Yangxue Liu  Zhen Yang  Tao Jiang  Nandakumar Katakam  Hossein Rouh  Liulei Ma  Yao Tang  Sultan Ahmed  Anis U Rahman  Hongen Huang  Daniel Unruh  Guigen Li 《国家科学评论(英文版)》2020,7(3):588

The first enantioselective assembly of sandwich-shaped organo molecules has been achieved by conducting dual asymmetric Suzuki-Miyaura couplings and nine other reactions. This work also presents the first fully C-C anchored multi-layer 3D chirality with optically pure enantiomers. As confirmed by X-ray diffraction analysis that this chiral framework is featured by a unique C₂-symmetry in which a nearly parallel fashion consisting of three layers: top, middle and bottom aromatic rings. Unlike the documented planar or axial chirality, the present chirality shows its top and bottom layers restrict each other from free rotation, i.e., this multi-layer 3D chirality would not exist if either top or bottom layer is removed. Nearly all multi-layered compounds showed strong luminescence of different colors under UV irradiation, and several randomly selected samples displayed aggregation-induced emission (AIE) properties. This work is believed to have broad impacts on chemical, medicinal and material sciences including optoelectronic materials in future.  相似文献   

Local and Global Processing in Blind and Sighted Children in a Naming and Drawing Task     

Ira Puspitawati  Ahmed Jebrane  Annie Vinter 《Child development》2014,85(3):1077-1090

This study investigated the spatial analysis of tactile hierarchical patterns in 110 early‐blind children aged 6–8 to 16–18 years, as compared to 90 blindfolded sighted children, in a naming and haptic drawing task. The results revealed that regardless of visual status, young children predominantly produced local responses in both tasks, whereas the production of integrated responses emerged later. Development of local and global processing seems to proceed similarly in the two populations, but local processing continued to occur at high levels over a larger age range in the blind. The possibility of visual mediation is pointed out, as totally blind children tended to process information locally more often than blind children with minimal light perception.  相似文献   

Using peer assessment of fieldwork to enhance students’ practical training     

Ahmed El-Mowafy 《Assessment & Evaluation in Higher Education》2014,39(2):223-241

Fieldwork training is a key component of several practical disciplines. In this study, students’ peer assessment of fieldwork is explored as a method to improve their practical training. Peer assessment theories are first discussed. A framework for peer assessment of fieldwork is proposed, and the steps taken for preparation of students for this task are discussed. A developed marking, feedback and moderation tool of assessment are presented. Application of peer assessment in the field was investigated over a period of two years in one undergraduate unit in the geospatial discipline as an example. Reliability of peer assessment was estimated by measuring the difference between assessments carried out by groups of peer assessors, and its validity was measured by comparing students’ marks with those given by tutors. Results show that students have gained from the peer assessment process, mainly as a formative form of assessment, by better understanding and endeavouring to achieve the objectives of field tasks. Tutors use differences among assessments made by groups of students compared to tutors’ assessments to identify field components that need better explanation of their content and assessment criteria.  相似文献   

Information Skills of Librarians Working at Public Universities in Bangladesh: A Task-Based Analysis of Pre- and Post-Training Performance Scores     

S. M. Zabed Ahmed  Shamima Yesmin 《International Information and Library Review》2013,45(3):239-246

Abstract

The main aim of this paper is to empirically examine the information skills of public university librarians and whether attending a short training on navigation to e-resources results in improvements in their knowledge base. A group of 33 librarians working at different public university libraries participated in this study. They were participants in a 90-min long training program on navigation to e-resources conducted at University Grants Commission of Bangladesh. The survey questionnaire, consisted of 12 information tasks, was distributed and answered before the training. The same tasks were repeated at the end of the training session to see the improvement of information skills. It was found that librarians did not have adequate knowledge of information skills; in fact, a major proportion of university librarians demonstrated inappropriate and insufficient knowledge before the training. The training helped improve their performance score significantly in six out of 12 tasks. The study concluded that the provision of systematic and regular training will improve the skills of librarians and it will positively affect their service outcomes.  相似文献   

Stabilization of positive Takagi–Sugeno fuzzy discrete-time systems with multiple delays and bounded controls     

Abdellah Benzaouia  Rkia Oubah  Ahmed El Hajjaji 《Journal of The Franklin Institute》2014

This paper deals with the problem of stabilization by state feedback control of Takagi–Sugeno (T–S) fuzzy discrete-time systems with multiple fixed delays while imposing positivity in closed-loop. The obtained results are presented under linear programming (LP) form. In particular, the synthesis of state feedback controllers is first solved in terms of Linear programming for the unbounded controls case. This result is then extended to the stabilization problem by nonnegative controls, and stabilization by bounded controls. The stabilization conditions are derived using the single Lyapunov–Krasovskii functional (LKF). An example of a real plant is studied to show the advantages of the design procedure. A comparison between linear programming and LMI approaches is presented.  相似文献   

Evaluation of Apoptotic Marker Bcl2, CD4+, Human Hepatocyte Growth Factor and Metalloproteinase-9 as Tumor Markers for Patients with Hepatocellular Carcinoma     

Eman R. Youness  Mohamed El Nemr  F. S. Oraby  Nadia M. Ahmed  Mohamed A. Moghni  Hanan F. Aly  Hanaa H. Ahmed 《Indian journal of clinical biochemistry : IJCB》2014,29(3):351-356

To examine the possible involvement of human B cell leukemia/lymphoma 2 (Bcl-2), CD4+ cells, hepatocyte growth factor (HGF), and metalloproteinase-9 (MMP-9), as biomarkers in early diagnosis of hepatocellular carcinoma (HCC), activities of these biomarkers in serum were demonstrated by the method of Enzyme Linked Immunosorbant Assay. Two groups of subjects (60 for each), were examined in this study; healthy controls and patients with HCC. The present results declare that, significant decrease in Bcl-2 (p ≤ 0.0001), and CD 4+ (p ≤ 0.001), while significant increase in HGF and MMP-9 (p ≤ 0.05). These findings imply an influence of these biomarkers by the existence of hepatic carcinoma that might reflect the progression of disease and a distinction between the pathological mechanisms involved in hepatic carcinoma. Since, the serum MMP-9 activity was significantly varied between each stage of HCC. An individual profile of the present investigated parameters was detected that might serve as an easy accessing serum marker to monitor the progression of hepatic cell disorders.  相似文献   

Review and redesign of the curriculum of a Masters programme in telecommunications engineering – Towards an outcome-based approach     

Khaled Gharaibeh  Bassam Harb  Haythem Bany Salameh  Asem Zoubi  Ahmed Shamali  Noel Murphy 《European Journal of Engineering Education》2013,38(2):194-210

This article presents the methodology and results of the curriculum review of the Masters of Science programme in Wireless Communications offered by the Telecommunications Engineering Department at Yarmouk University in Jordan. The review is based on expert opinion collected through questionnaires and meetings about the programme and focuses on two main aspects: the first is relevance of the programme to the needs of local and regional telecommunications industry and the second is comparability to similar programmes in the EU.

Through an extensive analysis of the collected data, a set of recommendations for improvement of the existing curriculum was developed. These recommendations were then used to redesign the curriculum with regard to contents, teaching methodology and assessment.  相似文献   

The Saudi Arabian international student experience: from a gender-segregated society to studying in a mixed-gender environment     

Ahmed Alhazmi  Berenice Nyland 《Compare》2013,43(3):346-365

In Saudi Arabia gender segregation is a cultural practice that occurs across all public and private domains. This segregation has shaped the lives of Saudi citizens and is driven socially through cultural and religious discourses and politically through regulation and policy. For Saudi students undertaking their education in western countries, the transitioning experience can be challenging. This paper draws on research conducted in Australia that has attempted to explore and understand this transitioning experience. The aim of the study was to highlight the dialectical relationship between participants’ cultural identity and the acculturation experience of cross-cultural contact. The findings indicate that Saudi students’ cultural identity has a significant influence on the experience of being in a mixed-gender environment. Findings also suggest a relationship between current experience and cultural identity. Drawing on in-depth interviews, the paper provides context to help understand the transitioning experience of Saudi students.  相似文献   

Elderly African Immigrants in Minnesota: A Case Study of Needs Assessment in Eight Cities     

Kebba Darboe  Lul S. Ahmed 《Educational gerontology》2013,39(10):855-866

Needs assessment is the process of identifying the gap between a target population's needs and its services. If a gap exists, a program can be designed to effectively respond to those needs. This aticle explores the needs of elderly African immigrants in Minnesota through the use of qualitative interviews. A convenience sampling was used to collect data from 200 available elderly people in eight cities in Minnesota. Data analyses revealed that 90% of them want appropriate nutrition and better delivery of services. Recommendations include support for informal caregivers like family members becuase these efforts can keep older people at home.  相似文献   

Quantitative changes of nitrergic neurons during postnatal development of chicken myenteric plexus     

Ping Yang  Jameel Ahmed Gandahi  Qian Zhang  Lin-li Zhang  Xun-guang Bian  Li Wu  Yi Liu  Qiu-sheng Chen 《Journal of Zhejiang University. Science. B》2013,14(10):886-895

Objective

Information regarding the development of the enteric nervous system (ENS) is important for understanding the functional abnormalities of the gut. Because fertilized chicken eggs provide easy access to embryos, chicken models have been widely used to study embryonic development of myenteric plexus; however, no study has been focused on the postnatal period. The aim of this study was to perform a qualitative and quantitative analysis of the nitrergic neurons in the myenteric plexus of developing chickens in the postnatal period.

Methods

Whole-mount preparations of the myenteric plexus were made in 7-d, 15-d, and 40-d old (adult) chickens of either sex (n=15). The myenteric plexus was studied after nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) histochemistry using light microscopy, digital photography, and Image-Pro Plus 6.0 software. The numbers of positively stained neurons and ganglia were counted in the duodenum, jejunum, ileum, caecum, and colon in the different age groups. Data were expressed as mean±standard deviation (SD), and statistical analysis was performed using a one-way analysis of variance (ANOVA) test.

Results

The positively stained neurons showed various morphologies and staining intensities, and formed bead-shaped and U-shaped arrangements in the myenteric plexus. The densities of neurons and ganglia increased with age. However, the number of positive neurons per ganglion increased. The number of NADPH-d-positive neurons was highest in the colon, followed by the ileum, the jejunum, the duodenum, and the caeca in all age groups.

Conclusions

Developmental changes in the myenteric plexus of chickens continue in the postnatal period, indicating that the maturation process of the gastrointestinal function is gradual. In addition, no significant difference is happening among different intestinal segments during postnatal development, suggesting that the function of different intestinal segments had been determined after birth.  相似文献