442 research outputs found
Synthesis and Characterization of Ordered and Disordered Mesoporous Alumina as High-Performance Molybdenum-99 Adsorbents
Molybdenum-99 (99Mo) is the parent radioisotope of technetium-99m (99mTc),an essential medical radioisotope for diagnostic agents in nuclear medicine.In 99Mo/99mTc generator, a chromatography column system with 99Mo adsorbent as afiller is usually used to produce 99mTc in hospitals. However, it is still challenging to find high-performance adsorbentsfor Mo adsorption.We have synthesized both ordered and disordered mesoporous alumina and compared their performance as 99Mo adsorbents. These materials were prepared via a soft-templated method using a triblock copolymer as the template, followed by air calcination at 400°C.The amount of nitric acid (HNO3) and the drying time were adjusted systematically to synthesize the ordered mesoporous alumina. The obtained ordered and disordered mesoporous alumina were characterized by low-and wide-angle X-ray diffractions (XRD), nitrogen adsorption-desorption, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The 99Mo adsorption capacities of these materials were evaluated by using the batch method. The experimental results show that the ordered mesoporous alumina hasa higher 99Mo adsorption capacity of 72.06 mg(Mo)g-1 than the disordered mesoporous alumina (50.12 mg(Mo)g-1). The results indicate the excellent potential of ordered mesoporous alumina as an adsorbent for the 99Mo/99mTc generator column
Modeling of a New Structure of Precision Air Conditioning System Using Secondary Condenser for Rh Regulation
A dynamic mathematical model for a new structure of precision air conditioning (PAC) has been developed. The proposed PAC uses an additional secondary condenser for relative humidity regulation compared to a basic refrigeration system. The work mechanism for this system and a vapour-compression cycle process of the system are illustrated using psychrometric chart and pressure-enthalpy diagram. A non-linear system model is derived based on the conservation of mass and energy balance principles and then linearized at steady state operating point for developing a 8th-order state space model suited for multivariable controller design. The quality of linearized model is analyzed in terms of transient response, controllability, observability, and interaction between input-output variables. The developed model is verified through simulation showing its ability for imitating the nonlinear behavior and the interaction of input-output variables
Diet Composition and Niche Breadth of Mullet Chelon Subviridis (Valenciennes, 1836) and Moolgarda Engeli (Bleeker, 1858) in Pabean Bay, Indramayu Subdistrict, West Java Province
Penelitian ini bertujuan untuk mengidentifikasi jenis dan komposisi serta luas dan tumpang tindih relung makanan ikan belanak di Teluk Pabean. Pengambilan contoh ikan dilakukan pada Juli hingga Desember 2016 dengan menggu-nakan alat tangkap sero dan jaring insang. Analisis data meliputi indeks bagian terbesar serta luas dan tumpang tindih relung makanan. Dua jenis ikan belanak, Chelon subviridis dan Moolgarda engeli, merupakan spesies yang banyak ditemukan di Teluk Pabean. Ukuran panjang tubuh C. subviridis yang diamati berkisar 73,34-185,72 mm dengan bobot 8,23-115,50 g dan panjang tubuh M. engeli berkisar 67,51-160,00 mm dengan bobot 6,91-96,70 g. Menu ma-kanan ikan belanak terdiri atas tiga kelompok besar, yaitu perifiton, larva organisme, dan detritus. Perifiton dari kelas Bacillariophyceae menjadi kelompok makanan yang banyak dimanfaatkan, khususnya Pleurosigma (35,81) oleh C. subviridis dan Nitzschia (27,89) oleh M. engeli. Perubahan komposisi jenis makanan terjadi pada setiap kelompok ukuran ikan. C. subviridis dan M. engeli memiliki relung makanan yang luas dengan nilai luas relung berturut-turut 5,995 dan 5,780. Luas relung makanan pada setiap kelompok ukuran ikan berbeda. Informasi mengenai luas relung makanan dapat menunjukkan adaptasi ikan belanak terhadap ketersediaan makanan di perairan
Unravelling social constructionism
Social constructionist research is an area of rapidly expanding influence that has brought together theorists from a range of different disciplines. At the same time, however, it has fuelled the development of a new set of divisions. There would appear to be an increasing uneasiness about the implications of a thoroughgoing constructionism, with some regarding it as both theoretically parasitic and politically paralysing. In this paper I review these debates and clarify some of the issues involved. My main argument is that social constructionism is not best understood as a unitary paradigm and that one very important difference is between what Edwards (1997) calls its ontological and epistemic forms. I argue that an appreciation of this distinction not only exhausts many of the disputes that currently divide the constructionist community, but also takes away from the apparent radicalism of much of this work
Abundance of Phytoplankton and its Role as Fish Food Sources in Pabean Bay, West Java
Pabean Bay is an estuary that has the potential of natural resources for fisheries. One of the organisms that has an important role here is phytoplankton. This study aims to analyze spatially and temporally the composition of phytoplankton abundance as fish food sources in Pabean Bay waters, West Java. Phytoplankton and physics-chemical parameters were taken monthly samples (June 2016-March 2017). Data analysis included the composition and abundance of phytoplankton, one-way variance analysis based on time and zone, the relation of physics-chemical parameters of aquatic to phytoplankton abundance, and phytoplankton used by fish as food. The abundance of phytoplankton differs on a monthly basis, but is not different in each zone. The phytoplankton found in the Pabean Bay is dominated by the Bacillariophyceae class. The dominant type of phytoplankton feeds from some of the captured fishes is Nitzschia and Pleurosigma from the Bacillariophyceae class.Teluk Pabean merupakan perairan estuari yang memiliki sumber daya alam potensial bagi perikanan. Salah satu organisme yang memiliki peran penting dalam teluk tersebut adalah fitoplankton. Penelitian ini bertujuan untuk menganalisis kelimpahan fitoplankton secara spasial dan temporal sebagai sumber makanan ikan di perairan Teluk Pabean, Jawa Barat. Pengambilan contoh fitoplankton dan pengukuran beberapa parameter fisik-kimiawi perairan dilakukan satu kali pada setiap bulan (Juni 2016-Maret 2017). Analisis data yang dilakukan meliputi komposisi dan kelimpahan fitoplankton, analisis ragam satu arah berdasarkan waktu dan zona pengamatan, kaitan parameter fisik-kimiawi perairan terhadap kelimpahan fitoplankton di Teluk Pabean, serta fitoplankton yang dimanfaatkan oleh ikan sebagai makanannya di Teluk Pabean, Jawa Barat. Kelimpahan fitoplankton tidak berbeda pada setiap zona pengamatan, tetapi kelimpahan fitoplankton berbeda antarwaktu pengamatan. Fitoplankton yang ditemukan di Teluk Pabean didominasi oleh fitoplankton kelas Bacillariophyceae. Jenis fitoplankton yang dominan menjadi makanan beberapa ikan di Teluk Pabean Jawa Barat yaitu Nitzschia dan Pleurosigma dari kelas Bacillariophyceae
Predictors of Intraspinal Pressure and Optimal Cord Perfusion Pressure After Traumatic Spinal Cord Injury.
BACKGROUND/OBJECTIVES: We recently developed techniques to monitor intraspinal pressure (ISP) and spinal cord perfusion pressure (SCPP) from the injury site to compute the optimum SCPP (SCPPopt) in patients with acute traumatic spinal cord injury (TSCI). We hypothesized that ISP and SCPPopt can be predicted using clinical factors instead of ISP monitoring. METHODS: Sixty-four TSCI patients, grades A-C (American spinal injuries association Impairment Scale, AIS), were analyzed. For 24Â h after surgery, we monitored ISP and SCPP and computed SCPPopt (SCPP that optimizes pressure reactivity). We studied how well 28 factors correlate with mean ISP or SCPPopt including 7 patient-related, 3 injury-related, 6 management-related, and 12 preoperative MRI-related factors. RESULTS: All patients underwent surgery to restore normal spinal alignment within 72Â h of injury. Fifty-one percentage had U-shaped sPRx versus SCPP curves, thus allowing SCPPopt to be computed. Thirteen percentage, all AIS grade A or B, had no U-shaped sPRx versus SCPP curves. Thirty-six percentage (22/64) had U-shaped sPRx versus SCPP curves, but the SCPP did not reach the minimum of the curve, and thus, an exact SCPPopt could not be calculated. In total 5/28 factors were associated with lower ISP: older age, excess alcohol consumption, nonconus medullaris injury, expansion duroplasty, and less intraoperative bleeding. In a multivariate logistic regression model, these 5 factors predicted ISP as normal or high with 73% accuracy. Only 2/28 factors correlated with lower SCPPopt: higher mean ISP and conus medullaris injury. In an ordinal multivariate logistic regression model, these 2 factors predicted SCPPopt as low, medium-low, medium-high, or high with only 42% accuracy. No MRI factors correlated with ISP or SCPPopt. CONCLUSIONS: Elevated ISP can be predicted by clinical factors. Modifiable factors that may lower ISP are: reducing surgical bleeding and performing expansion duroplasty. No factors accurately predict SCPPopt; thus, invasive monitoring remains the only way to estimate SCPPopt
Oh Comrade, What Times those Were! History, Capital Punishment and the Urban Square.
From the perspective of traditional Western histories of the urban realm, public squares have been seen to represent a privileged site of urban containment expressive of a community's highest values of individual freedom, social inclusion and cultural refinement. But such views can be misleading. For what is omitted from the scope of these conventional historical visions and their ideal and conforming subjects of public spatial discourse, is an entire array of other and darker narratives that equally speak of personal choice, collective participation and cultural value. Capital punishment reflects such an example, a practice that once comprised an integral part of the political, social and cultural landscape of a Western city's squares and streets. Drawing from Michel Foucault's Discipline and Punish and its implications on how we might begin to re-read the history of the urban square, the following seeks to explore those practices and modes of rationality that underpinned the once public spectacle of executions and torture as a vital condition of urban life. In particular, this discussion will question the assumptions of an historical tradition that continues to reduce our understanding of the city and its open spaces of public appearance and action to an idealistic and illusory reality of the urban realm and its narrow framing of collective conduct, necessity and significance
Gender differences in conversation topics, 1922–1990
Gender differences in conversation topics were first systematically studied in 1922 by Henry Moore, who theorized that the gender differences in topic choice he observed in a field observation study would persist over time, as they were manifestations of men's and women's “original natures.” In this paper, I report a 1990 replication of Moore's study, in which similar but smaller gender differences in topic choice are found. In order to explore further the apparent trend toward smaller gender differences, reports of quantitative observation studies conducted between 1922 and 1990 are examined. Other explanations besides change over time—such as variations in conversation setting and audience, target populations, and researcher's intentions—may account for the decline in gender differences in topic choice. Social influences are seen more clearly in the discourse about gender differences in conversation than in gender differences in conversation topics themselves.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45599/1/11199_2004_Article_BF00289744.pd
Musculoskeletal symptoms of the upper extremities and the neck: A cross-sectional study on prevalence and symptom-predicting factors at visual display terminal (VDT) workstations
<p>Abstract</p> <p>Background</p> <p>The aim of this study was to determine the prevalence and the predictors of musculoskeletal symptoms in the upper extremities and neck at visual display terminal (VDT) workstations.</p> <p>Methods</p> <p>In a cross-sectional study 1,065 employees working at VDT > 1 h/d completed a standardised questionnaire. Workstation conditions were documented in a standardised checklist, and a subgroup of 82 employees underwent a physical examination.</p> <p>Results</p> <p>Using the Nordic Questionnaire, the 12-month prevalence of symptoms of the neck, shoulder region, hand/wrist, or elbow/lower arm was 55%, 38%, 21%, and 15% respectively. The duration of VDT work had a significant impact on the frequency of neck symptoms in employees performing such work > 6 h/d.</p> <p>Conclusion</p> <p>With regard to musculoskeletal symptoms of the upper extremities, preventive measures at VDT workstations should be focused on neck and shoulder symptoms (e.g. ergonomic measures, breaks to avoid sitting over long periods).</p
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