9,879 research outputs found
Applications of Biological Flocculants (BFs) for Coagulation Treatment in Water Purification: Turbidity Elimination
In this study, coagulation performance by using biological flocculants (BFs; produced from strain Bacillus sp. F6) for turbidity removal was investigated. The results demonstrated that BFs were able to eliminate turbidity from kaolin clay solution over a wide dosage range (γDR = 6-20 mg L-1). The removal efficiency with BFs reached 86 % on average, lower than 95 % with Al2(SO4)3 (γAl = 6.5 mg L-1) and 96 % with Fe2(SO4)3 (γFe = 10 mg L-1), respectively. For bioflocculants, bridging flocculation other than charge neutralization should be responsible for turbidity removal. The combined applications of BFs with Al2(SO4)3 (ζAl/BF = 0.33) and Fe2(SO4)3 (ζFe/BF = 0.05) increased overall turbidity removal up to 97 %. It was also shown that combination of BFs and Fe2(SO4)3 was effective for removing turbidity from raw water. This study provides a proof-in-concept demonstration of BFs for water purification, which can in part reduce operational costs in coagulation treatment, as well, effectively reduce the concentration of residual metallic elements (e.g. aluminum) in coagulated solution
Applications of Biological Flocculants (BFs) for Coagulation Treatment in Water Purification: Turbidity Elimination
In this study, coagulation performance by using biological flocculants (BFs; produced from strain Bacillus sp. F6) for turbidity removal was investigated. The results demonstrated that BFs were able to eliminate turbidity from kaolin clay solution over a wide dosage range (γDR = 6-20 mg L-1). The removal efficiency with BFs reached 86 % on average, lower than 95 % with Al2(SO4)3 (γAl = 6.5 mg L-1) and 96 % with Fe2(SO4)3 (γFe = 10 mg L-1), respectively. For bioflocculants, bridging flocculation other than charge neutralization should be responsible for turbidity removal. The combined applications of BFs with Al2(SO4)3 (ζAl/BF = 0.33) and Fe2(SO4)3 (ζFe/BF = 0.05) increased overall turbidity removal up to 97 %. It was also shown that combination of BFs and Fe2(SO4)3 was effective for removing turbidity from raw water. This study provides a proof-in-concept demonstration of BFs for water purification, which can in part reduce operational costs in coagulation treatment, as well, effectively reduce the concentration of residual metallic elements (e.g. aluminum) in coagulated solution
Screening of patients with tuberculosis for diabetes mellitus in China.
Objectiveâ There is a high burden of both diabetes (DM) and tuberculosis (TB) in China, and this study aimed to assess feasibility and results of screening patients with TB for DM within the routine healthcare setting of six health facilities. Methodâ Agreement on how to screen, monitor and record was reached in May 2011 at a stakeholders' meeting, and training was carried out for staff in the six facilities in July 2011. Implementation started in September 2011, and we report on 7âmonths of activities up to 31 March 2012. Resultsâ There were 8886 registered patients with TB. They were first asked whether they had DM. If the answer was no, they were screened with a random blood glucose (RBG) followed by fasting blood glucose (FBG) in those with RBGââ„â6.1âmm (one facility) or with an initial FBG (five facilities). Those with FBGââ„â7.0âmm were referred to DM clinics for diagnostic confirmation with a second FBG. Altogether, 1090 (12.4%) patients with DM were identified, of whom 863 (9.7%) had a known diagnosis of DM. Of 8023 patients who needed screening for DM, 7947 (99%) were screened. This resulted in a new diagnosis of DM in 227 patients (2.9% of screened patients), and of these, 226 were enrolled to DM care. In addition, 575 (7.8%) persons had impaired fasting glucose (FBG 6.1 to <7.0âmm). Prevalence of DM was significantly higher in patients in health facilities serving urban populations (14.0%) than rural populations (10.6%) and higher in hospital patients (13.5%) than those attending TB clinics (8.5%). Conclusionâ This pilot project shows that it is feasible to screen patients with TB for DM in the routine setting, resulting in a high yield of patients with known and newly diagnosed disease. Free blood tests for glucose measurement and integration of TB and DM services may improve the diagnosis and management of dually affected patients
Waves of intermediate length through an array of vertical cylinders
We report a semi-analytical theory of wave propagation through a vegetated water. Our aim is to construct a mathematical model for waves propagating through a lattice-like array of vertical cylinders, where the macro-scale variation of waves is derived from the dynamics in the micro-scale cells. Assuming infinitesimal waves, periodic lattice configuration, and strong contrast between the lattice spacing and the typical wavelength, the perturbation theory of homogenization (multiple scales) is used to derive the effective equations governing the macro-scale wave dynamics. The constitutive coefficients are computed from the solution of micro-scale boundary-value problem for a finite number of unit cells. Eddy viscosity in a unit cell is determined by balancing the time-averaged rate of dissipation and the rate of work done by wave force on the forest at a finite number of macro stations. While the spirit is similar to RANS scheme, less computational effort is needed. Using one fitting parameter, the theory is used to simulate three existing experiments with encouraging results. Limitations of the present theory are also pointed out.Cornell University (Mary Upson visiting professorship
A balanced homodyne detector for high-rate Gaussian-modulated coherent-state quantum key distribution
We discuss excess noise contributions of a practical balanced homodyne
detector in Gaussian-modulated coherent-state (GMCS) quantum key distribution
(QKD). We point out the key generated from the original realistic model of GMCS
QKD may not be secure. In our refined realistic model, we take into account
excess noise due to the finite bandwidth of the homodyne detector and the
fluctuation of the local oscillator. A high speed balanced homodyne detector
suitable for GMCS QKD in the telecommunication wavelength region is built and
experimentally tested. The 3dB bandwidth of the balanced homodyne detector is
found to be 104MHz and its electronic noise level is 13dB below the shot noise
at a local oscillator level of 8.5*10^8 photon per pulse. The secure key rate
of a GMCS QKD experiment with this homodyne detector is expected to reach
Mbits/s over a few kilometers.Comment: 22 pages, 11 figure
Morphology Effectively Controls Singlet-Triplet Exciton Relaxation and Charge Transport in Organic Semiconductors
We present a comparative study of ultrafast photo-conversion dynamics in
tetracene (Tc) and pentacene (Pc) single crystals and Pc films using optical
pump-probe spectroscopy. Photo-induced absorption in Tc and Pc crystals is
activated and temperature-independent respectively, demonstrating dominant
singlet-triplet exciton fission. In Pc films (as well as C-doped films)
this decay channel is suppressed by electron trapping. These results
demonstrate the central role of crystallinity and purity in photogeneration
processes and will constrain the design of future photovoltaic devices.Comment:
Type II spiral ganglion afferent neurons drive medial olivocochlear reflex suppression of the cochlear amplifier.
The dynamic adjustment of hearing sensitivity and frequency selectivity is mediated by the medial olivocochlear efferent reflex, which suppresses the gain of the 'cochlear amplifier' in each ear. Such efferent feedback is important for promoting discrimination of sounds in background noise, sound localization and protecting the cochleae from acoustic overstimulation. However, the sensory driver for the olivocochlear reflex is unknown. Here, we resolve this longstanding question using a mouse model null for the gene encoding the type III intermediate filament peripherin (Prph). Prph((-/-)) mice lacked type II spiral ganglion neuron innervation of the outer hair cells, whereas innervation of the inner hair cells by type I spiral ganglion neurons was normal. Compared with Prph((+/+)) controls, both contralateral and ipsilateral olivocochlear efferent-mediated suppression of the cochlear amplifier were absent in Prph((-/-)) mice, demonstrating that outer hair cells and their type II afferents constitute the sensory drive for the olivocochlear efferent reflex
The Case for Dynamic Models of Learners' Ontologies in Physics
In a series of well-known papers, Chi and Slotta (Chi, 1992; Chi & Slotta,
1993; Chi, Slotta & de Leeuw, 1994; Slotta, Chi & Joram, 1995; Chi, 2005;
Slotta & Chi, 2006) have contended that a reason for students' difficulties in
learning physics is that they think about concepts as things rather than as
processes, and that there is a significant barrier between these two
ontological categories. We contest this view, arguing that expert and novice
reasoning often and productively traverses ontological categories. We cite
examples from everyday, classroom, and professional contexts to illustrate
this. We agree with Chi and Slotta that instruction should attend to learners'
ontologies; but we find these ontologies are better understood as dynamic and
context-dependent, rather than as static constraints. To promote one
ontological description in physics instruction, as suggested by Slotta and Chi,
could undermine novices' access to productive cognitive resources they bring to
their studies and inhibit their transition to the dynamic ontological
flexibility required of experts.Comment: The Journal of the Learning Sciences (In Press
How Volatile is ENSO for Global Greenhouse Gas Emissions and the Global Economy?
This paper analyzes two indexes in order to capture the volatility inherent in El Niños Southern Oscillations (ENSO), develops the relationship between the strength of ENSO and greenhouse gas emissions, which increase as the economy grows, with carbon dioxide being the major greenhouse gas, and examines how these gases affect the frequency and strength of El Niño on the global economy. The empirical results show that both the ARMA(1,1)-GARCH(1,1) and ARMA(3,2)-GJR(1,1) models are suitable for modelling ENSO volatility accurately, and that 1998 is a turning point, which indicates that the ENSO strength has increased since 1998. Moreover, the increasing ENSO strength is due to the increase in greenhouse gas emissions. The ENSO strengths for Sea Surface Temperature (SST) are predicted for the year 2030 to increase from 29.62% to 81.5% if global CO2 emissions increase by 40% to 110%, respectively. This indicates that we will be faced with even stronger El Nino or La Nina effects in the future if global greenhouse gas emissions continue to increase unabated
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