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461.
The aim of this study is twofold: firstly, to characterize the biochars resulting from the hydrothermal carbonization (HTC) of different types of wetland biomass and, secondly, to assess their potential for ammonia removal in aqueous solutions. The chars produced were carbon rich. The adsorption experiments indicated that hydrothermal treatment improved the ammonia removal efficiency rate, and loaded adsorbents were regenerable. Using an HTC char of reed as adsorbent has several advantages: it has the highest adsorption performance, the highest char yield, and the greatest affinity for regeneration.  相似文献   
462.
Musculoskeletal infection is one of the most common complications associated with surgical fixation of bones fractured during trauma. These infections usually involve bacterial colonisation and biofilm formation on the fracture fixation device itself, as well as infection of the surrounding tissues. Antibiotic prophylaxis, wound debridement and postsurgical care can reduce the incidence of, but do not prevent, these infections. Much research and development has been focussed on ways to further reduce the incidence of infection and in the following short review we describe our experiences investigating the contribution of the basic design of fracture fixation devices on the susceptibility to infection. It has been shown in animal studies that device size, shape, mode of action and material and topography play an interrelated role in the susceptibility to infection. Although direct extrapolation from animal studies to the clinical setting is difficult, close consideration of the design factors that can reduce the incidence of infection in animal models is expected to help minimise the incidence of infection associated with any clinically implemented fracture fixation device.  相似文献   
463.
Proximal spinal muscular atrophy (SMA) is an autosomal recessive neurodegenerative disorder characterized by motor neuron loss and subsequent atrophy of skeletal muscle. SMA is caused by deficiency of the essential survival motor neuron (SMN) protein, canonically responsible for the assembly of the spliceosomal small nuclear ribonucleoproteins (snRNPs). Therapeutics aimed at increasing SMN protein levels are efficacious in treating SMA. However, it remains unknown how deficiency of SMN results in motor neuron loss, resulting in many reported cellular functions of SMN and pathways affected in SMA. Herein is a perspective detailing what genetics and biochemistry have told us about SMA and SMN, from identifying the SMA determinant region of the genome, to the development of therapeutics. Furthermore, we will discuss how genetics and biochemistry have been used to understand SMN function and how we can determine which of these are critical to SMA moving forward.  相似文献   
464.
465.
This study examines the timing using computer-enriched instruction (CEI), before or after a traditional lecture to determine cross-over effect, period effect, and learning effect arising from sequencing of instruction. A 2 × 2 cross-over design was used with CEI to teach central limit theorem (CLT). Two sequences of graduate students in nursing participated in this study. Sequence A was given the CEI and handout first, followed by a traditional lecture and handout. Sequence B was given a lecture and handout first, followed by the CEI and handout. A pre-test and posttests (posttest1 after the first presentation and posttest2 after the second presentation) were given to measure instructional outcomes. All tests were 10 multiple choice questions with four options and only one option was the correct answer.  相似文献   
466.
Cost pressure and rising throughput requirements are important drivers for assay miniaturization. Typical examples for the trend “smaller is better” are found in BioChip applications and in High Throughput Screening (HTS), which is evolving from the 96-well standard to high-density microplates with 384, 864, 1536 or more wells. These applications require the automated pipetting of liquids in the submicroliter volume range, a difficult task for traditional automated liquid handling systems based on syringe pumps. Tecan developed a new device for the accurate pipetting of volumes in the nanoliter range. Based on ink-jet printer technology, this device allows the exact control of the volume of the ejected droplets via a set of parameters. The integration of this new technology into Tecan's flexible xyz-platforms allows an easy use of this powerful technology for several applications. Results such as volume range, accuracy and precision are discussed.  相似文献   
467.
A normative sample of 880 children was contrasted with a sample of 276 sexually abused children on the Child Sexual Behavior Inventory (CSBI), a 35-item behavior checklist assessing sexual behavior in children 2–12 yrs old. The CSBI total score differed significantly between the 2 groups after controlling for age, sex, maternal education, and family income, with sexually abused children showing a greater frequency of sexual behaviors than did the normative sample. Test–retest reliability, interitem correlations, cross-validation, and correlations with abuse characteristics were also reported. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
468.
As the use of web-based homework delivery and checking systems expands, we have greater need to evaluate how students engage with these systems and how changes in the systems influence student behavior. Reported here is the assessment of WeBWorK, an open-source web-based homework program used largely in postsecondary math and science courses, with recent extension to high school courses. WeBWorK draws from a large library of problems to generate individual assignments and provides immediate feedback about correctness of students’ answers. WeBWorK allows entries in multiple choice, formula and numerical formats. The entries recorded by the system create an extensive database of student interactions with the system.In our two-part study, we (1) review 2387 student surveys about WeBWorK in three semesters across a range of mathematics courses and (2) test a model designed to classify student responses to system feedback, permitting a fine-grained analysis of the system’s records at the keystroke level for a cohort of 96 Calculus I students.Based on this data, our goals are, first, to understand how students use the system and respond to its feedback; second, to analyze the impact of upgrades to the system interface on student users, and third, to evaluate the efficiency of training raters to classify student records.We find that the introduction of new features to the WeBWorK interface (improvements generated by our initial assessment) were welcomed by most students and reduced the overall number of submitted errors by half by the third year of the study. Importantly, the interface improvements reduced the number of errors that were not pedagogically useful. We also find that our error classification model, called here the Student Response Model, was a good fit for our student sample, as reflected by inter-rater reliability of three raters who coded the student records. In sum, our error classification model appears to be useful for analyzing formula entries. To make this assessment model widely available, we designed a system of exercises to train raters to classify student response files for WeBWorK and similar web-based systems.  相似文献   
469.
This paper presents an evaluation of different keyboard display coding schemes for the operation of a speech synthesizer by children with cerebral palsy. The synthesizer uses 128 function keys to access 393 words and 45 phonemes. Most keys activate four different words or phrases, requiring the user to search for the desired word and to select the correct positional level prior to pressing the key. This process was quite slow with the existing machine due to the design of the keyboard display. A study was conducted in which five cerebral palsied subjects operated the device using four additional keyboard overlays representing different combinations of colour coding and lettering case. The time was measured for subjects to key in 10-word sequences. It was determined that one overlay using a colour and position redundant coding scheme with upper-case lettering resulted in a saving of more than 20 s/word compared with the original display.  相似文献   
470.
Development of megakaryocyte (MK) from CD34+ cord blood (CB) cells in both plasma clot culture and liquid culture was significantly inhibited by human platelet factor 4 (PF4) and human transforming growth factor beta 1 (TGF beta 1). Inhibition of cell growth by PF4 was reversible judging from the fact that the CD34+ cells preincubated with PF4 could regenerate colonies after washing and replating into the cultures. By contrast, TGF beta 1-pretreated CD34+ cells gave rise to few colonies following replating. Moreover, incubation of CD34+ cells with PF4 in liquid culture caused an increase in the number of both stem cell factor (SCF)-binding cells and CD34 antigen-bearing cells, and exhibited greater capacity to form MK colonies than control after the treatment of 5-FU. In vivo in mice, twice injections of PF4 at 40 micrograms/kg resulted in a significant increase in the number of colony-forming cells with high proliferative potential (HPP-CFC) and colony-forming unit-megakaryocyte (CFU-MK) in bone marrow. In exponentially growing human erythroleukemia cells (HEL), the addition of PF4 prolonged cell cycle progression and therefore resulted in an increased cell population in S phase, as determined by flow cytometric analysis. Different from PF4, TGF beta 1 blocked more cells in G1 phase. These results demonstrate that PF4 and TGF beta 1 inhibit MK development from CD34+ CB cells by different mechanisms and suggest that PF4, unlike TGF beta 1, exerts its inhibitory effect on cell growth in a reversible and S phase-specific manner by which it protects stem cells and MK progenitor cells from 5-FU cytotoxicity.  相似文献   
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