Low Coupling Ratio Research Articles

Process system simulation of coupled pyrolysis disposal of domestic waste in coal-fired boiler and pilot study on dioxin emission

The disposal of domestic waste has become a critical and costly problem. Incineration for power generation is currently the primary domestic waste treatment method. Due to its small capacity and low parameters, domestic waste incineration is generally uneconomical and associated with significant risks to public health and environmental safety. The coal-fired power plants are generally characterized with huge capacity and high parameters, consequently resulting in much higher power generation efficiency with lower cost emission control. This indicates that co-disposal of domestic waste using existing coal-fired units may significantly reduce its treatment costs associated with the improvement of utilization efficiency and environmental risks. Base on this, a highly-flexible coupling of pyrolysis-pretreated solid waste in pulverized coal furnace is proposed in this paper, and field tests and numerical simulations have been carried out separately according to the process route. The results show that after coupling with pulverized coal boiler, domestic waste pyrolysis pretreatment unit can operate self-sustainably without external energy supply and the process route is feasible. Furthermore, the coupled co-combustion of domestic waste pyrolysis products and pulverized coal was simulated by fluent software. Compared with pure pulverized coal combustion, mixing domestic waste pyrolysis products can promote pulverized coal combustion in the furnace and help the pulverized coal boiler to burn stably at low load. The emission concentrations of NOx at the outlet of the furnace are 530 ppm, 545 ppm and 478 ppm respectively when pulverized coal is burned purely and mixed with 100 t/d and 200 t/d domestic waste. the NOx emissions could be reduced to a certain extent by mixing domestic waste. On the basis of previous research, the field test of coupling disposal of domestic waste by pulverized coal boiler was carried out, and the dioxin concentration in flue gas and fly ash was tested emphatically. The results show that when the amount of waste is less than 4 %, the concentration of dioxin in flue gas is 0.0107 ng TEQ/m3, which meets the latest emission standard of air pollutants in Shanghai coal-fired sludge power plant of 0.02 ng TEQ/m3. Low proportion of domestic waste will not increase the production and emission of dioxins. These studies show that it is feasible and promising to treat municipal solid waste with low coupling ratio by using existing coal-fired units.

Fault Coupling on a Creeping Thrust Fault: Joint Inversion Using Geodetic Data and Repeating Earthquakes

AbstractDue to the lack of recognized creep on dip‐slip faults, the nature of fault creep and its role in the generation of large earthquakes is largely unexplored. The Chihshang fault in Taiwan serves as one of the best examples of a thrust creeping fault in the world, exhibiting a fast creep rate of 2–3 cm/year and the capability of producing magnitude six earthquakes. Land‐based geodetic measurements are less sensitive to fault slip with depth, especially for the deeper portion of the seaward dipping fault. Taking advantage of slip rates inferred from repeating earthquake sequences (RESs) at greater depths (up to 30 km), we present a method that embeds RES‐derived slip rates into the neighboring fault patch for geodetic data inversion. Using the geodetic and seismological data from 2007 to 2011, we achieve a higher resolution of inter‐seismic slip rate distribution below a depth of 10 km. The inferred low coupling ratio establishes an extensive creeping area that coincides with a location of abundant RES and earthquake swarms. The inferred high coupling ratio, on the other hand, delineates a locked area corresponding to the two co‐seismic slip zones of the 2003 Mw 6.8 Chengkung and 2022 Mw 6.7 Yuli earthquakes. The transition zone marking the gradual change from fully locked to shallow creeping areas appears to coincide with the post‐seismic slip area of the 2003 Chengkung event. Using the fault coupling model, the moment rate deficit measured in the two locked areas is capable of generating a Mw 6.8 event every 78 years to the south and a Mw 6.7 event every 28 years to the north. This moment rate deficit is decreased by 10% when the closely located Central Range fault is considered in a two‐fault model, leading to the slightly longer recurrence interval on the Chihshang fault. The two‐fault model potentially contributes to a better understanding of the regional inter‐seismic deformation, which is recommended to be adopted in the future studies of seismic hazard assessment.

Design of a Compliant Vertical Micropositioning Stage Based on Lamina Emergent Mechanisms

This article presents the design and development of a novel compliant vertical micropositioning stage (VMS) with a millimeter stroke and compact profile. The concept design of the stage is inspired by lamina emergent mechanisms. The overall mechanism is fabricated using a plate-like material, which can realize an out-of-plane motion vertical to the mechanism plane. The proposed architectural design guarantees the advantages of the center platform in terms of millimeter stroke, high compactness, and low displacement coupling ratio. Analytical models of the stiffness and resonant frequency of the stage are established by resorting to pseudorigid-body model and Lagrangian equations. They are validated by conducting simulation study with finite element analysis. For performance testing, a prototype stage driven by a voice coil motor is fabricated. Experimental results indicate that the stage (size: 100 mm × 100 mm × 5 mm) delivers a working stroke of 5.58 mm, displacement coupling ratio of 0.31%, and resolution of 0.71 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu$</tex-math></inline-formula> m. It exhibits more geometric advantages over existing piezoelectric-actuated vertical stages. In addition, it has superior vertical compactness, linearity, and simplicity compared to a planar mechanism with vertical input and vertical output. The concept design proposed in this article provides a new solution for the design and development of compliant VMS.

Astrocytic K+ clearance during disease progression in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder in which patients lose motor functions due to progressive loss of motor neurons in the cortex, brainstem, and spinal cord. Whilst the loss of neurons is central to the disease, it is becoming clear that glia, specifically astrocytes, contribute to the onset and progression of neurodegeneration. Astrocytes play an important role in maintaining ion homeostasis in the extracellular milieu and regulate multiple brain functions by altering their extracellular concentrations. In this study, we have investigated the ability of astrocytes to maintain K+ homeostasis in the brain via direct measurement of the astrocytic K+ clearance rate in the motor and somatosensory cortices of an ALS mouse model (SOD1G93A ). Using electrophysiological recordings from acute brain slices, we show region-specific alterations in the K+ clearance rate, which was significantly reduced in the primary motor cortex but not the somatosensory cortex. This decrease was accompanied by significant changes in astrocytic morphology, impaired conductivity via Kir4.1 channels and low coupling ratio in astrocytic networks in the motor cortex, which affected their ability to form the K+ gradient needed to disperse K+ through the astrocytic syncytium. These findings indicate that the supportive function astrocytes typically provide to motoneurons is diminished during disease progression and provides a potential explanation for the increased vulnerability of motoneurons in ALS.

Alignment & stability challenges for FCC-ee

In order to achieve its ultra-low vertical emittance (1 pm) and high luminosity (of up to 230 times 10^{34}text{ cm}^{-2}text{ s}^{-1} per collision point), the e+e− Future Circular Collider (FCC-ee) requires a well-informed alignment strategy, powerful correction methods, and good understanding of the impact of vibrations. The large ring size, high natural chromaticity, small beta ^{*}, and the low coupling ratio make the FCC-ee design susceptible to misalignment and field errors, which if not properly addressed, threaten to increase the horizontal and vertical emittances and adversely affect the luminosity. Tight alignment tolerances around the 100 km ring would be a major cost driver and therefore alignment and stability need to be carefully studied. In this paper we present a status update, in which we apply analytical estimate methods, verified with simulation data, to determine the influence of the alignment of specific magnet types with the result informing the relative alignment tolerances. This is followed by simulations of a correction strategy that includes a large set of magnet misalignments and field errors. Finally, we also consider the tolerances on vibrations of quadrupoles through evaluating three cases: coherent vibration due to external seismic motion, vibrations resonant with the betatron frequency, and non-resonant, incoherent vibration.

Earthquake swarms in Taiwan: A composite declustering method for detection and their spatial characteristics

Earthquake swarms can act as indicators of fluid activity and aseismic transients at depth. As a young and active collisional mountain belt with frequent earthquakes, Taiwan is a natural laboratory for studying the physical mechanisms controlling the characteristics of swarm activity in this complex tectonic environment. Where the earthquake swarms tend to occur and how they reflect the aseismic deformation in this young orogen? In this study, we propose a composite swarm detection method that relies on the correlation of mainshock density rates derived from three distinct declustering algorithms. Using earthquakes in Taiwan from 1990–2019 with magnitudes greater than or equal to three and at depths less than 50 km, 153 swarm sequences were identified as characterized by an event number greater than ten, a time span of less than fifteen days, and a maximum magnitude of 5.79. The swarm sequences were found to be active at locations with a high seismicity rate (>0.2yr−1km−2) but not an anomalous b-value, suggesting that the environment with a high rate of earthquake occurrence is linked with the mechanism for swarm generation. They were found to largely overlap with the repeating earthquakes, as approximately 86% of the 1857 repeating events in Taiwan are closely located to swarm events. Such overlap is found to be largest in the southern Longitudinal Valley where a creeping fault is located and where a low coupling ratio was inferred. Consequently, it is proposed that the active collision boundary experiencing a high creep rate and the areas experiencing episodic aseismic slip are capable of producing active swarm sequences in Taiwan.

Dissecting the low catalytic capability of flavin-dependent halogenases

Although flavin-dependent halogenases (FDHs) are attractive biocatalysts, their practical applications are limited because of their low catalytic efficiency. Here, we investigated the reaction mechanisms and structures of tryptophan 6-halogenase (Thal) from Streptomyces albogriseolus using stopped-flow, rapid-quench flow, quantum/mechanics molecular mechanics calculations, crystallography, and detection of intermediate (hypohalous acid [HOX]) liberation. We found that the key flavin intermediate, C4a-hydroperoxyflavin (C4aOOH-FAD), formed by Thal and other FDHs (tryptophan 7-halogenase [PrnA] and tryptophan 5-halogenase [PyrH]), can react with I−, Br−, and Cl− but not F− to form C4a-hydroxyflavin and HOX. Our experiments revealed that I− reacts with C4aOOH-FAD the fastest with the lowest energy barrier and have shown for the first time that a significant amount of the HOX formed leaks out as free HOX. This leakage is probably a major cause of low product coupling ratios in all FDHs. Site-saturation mutagenesis of Lys79 showed that changing Lys79 to any other amino acid resulted in an inactive enzyme. However, the levels of liberated HOX of these variants are all similar, implying that Lys79 probably does not form a chloramine or bromamine intermediate as previously proposed. Computational calculations revealed that Lys79 has an abnormally lower pKa compared with other Lys residues, implying that the catalytic Lys may act as a proton donor in catalysis. Analysis of new X-ray structures of Thal also explains why premixing of FDHs with reduced flavin adenine dinucleotide generally results in abolishment of C4aOOH-FAD formation. These findings reveal the hidden factors restricting FDHs capability which should be useful for future development of FDHs applications.

Proposal of an Equal-Stiffness and Equal-Stroke 2D Micro-Positioning Platform Driven by Piezoelectric Actuators

Micro-positioning platform plays an important role in the field of precision positioning such as microelectronics, robotics and biomedicine. This paper proposes an equal-stiffness and equal-stroke 2D micro-positioning platform, which is driven by piezoelectric actuators. The overall structure of the 2D micro-positioning platform adopts a nested structure and the displacement magnification mechanism adopts two hourglass displacement magnification mechanisms. The displacement magnification ratio of the hourglass displacement magnification mechanism was studied, and its structural parameters were optimized. Static stiffness analysis and simulation analysis of the micro-positioning platform were carried out. The simulation stiffness of the micro-positioning platform in the XY direction is 46873 N/m and 46832 N/m respectively. The experimental prototype of the micro-positioning platform was built. Through the measurement experiment with the prototype, the maximum stroke of the micro-positioning platform in the XY direction is 489 μm and 493 μm respectively; the maximum coupling ratio in the XY direction is 2.38% and 2.70% respectively. The research indicates that the micro-positioning platform had the characteristics of small size, equal long stroke, equal stiffness and low coupling ratio in the XY direction.

The sarcoplasmic reticulum and SERCA: a nexus for muscular adaptive thermogenesis.

We are currently facing an "obesity epidemic" worldwide. Promoting inefficient metabolism in muscle represents a potential treatment for obesity and its complications. Sarco(endo)plasmic reticulum (SR) Ca2+-ATPase (SERCA) pumps in muscle are responsible for maintaining low cytosolic Ca2+ concentration through the ATP-dependent pumping of Ca2+ from the cytosol into the SR lumen. SERCA activity has the potential to be a critical regulator of body mass and adiposity given that it is estimated to contribute upwards of 20% of daily energy expenditure. More interestingly, this fraction can be modified physiologically in the face of stressors, such as ambient temperature and diet, through its physical interaction with several regulators known to inhibit Ca2+ uptake and muscle function. In this review, we discuss advances in our understanding of Ca2+-cycling thermogenesis within skeletal muscle, focusing on SERCA and its protein regulators, which were thought previously to only modulate muscular contractility. Novelty ATP consumption by SERCA pumps comprises a large proportion of resting energy expenditure in muscle and is dynamically regulated through interactions with small SERCA regulatory proteins. SERCA efficiency correlates significantly with resting metabolism, such that individuals with a higher resting metabolic rate have less energetically efficient SERCA Ca2+ pumping in muscle (i.e., lower coupling ratio). Futile Ca2+ cycling is a versatile heat generating mechanism utilized by both skeletal muscle and beige fat.

Design and wide-bandwidth control of large aperture fast steering mirror with integrated-sensing unit

Abstract This paper reports the design and wide-bandwidth control of a large aperture fast steering mirror (FSM) with integrated-sensing units. The developed FSM is driven by electromagnetic actuators and guided by a flexible support to achieve kinematic decoupling and large angle. Four flexible beams are used as sensing units for feedback control. A theoretical analysis of rotational stiffness was conducted to evaluate the mirror’s output angle. The dynamic characteristics were also modeled to investigate the relationship between the input voltage and the output angle of the entire system. To improve the bandwidth, a modified proportional-integral-derivative (PID) control strategy combined with feedforward compensation was employed. The prototype of the structure was fabricated and evaluated experimentally to investigate its kinematic and dynamic performance. The experimental results revealed that the angle travelled for more than 60 mrad, for both axes, with a low coupling ratio of less than 0.24%. Finally, the effectiveness of the designed controller was verified. The tracking experiment was also conducted to investigate the tracking performance of the proposed FSM.

An up-to-date crustal deformation map of Iran using integrated campaign-mode and permanent GPS velocities

We present the most extensive and up-to-date unified GPS velocity field for Iran. We processed the data collected during 10 yr (2006–2015) from the Iranian Permanent GNSS Network (IPGN) and combined them with previously published velocity solutions from the GPS survey measurements during 1997–2013. We analysed this velocity field using a continuum approach to compute a new strain-rate map for this region and we designed a block model based on the main geological, morphological and seismic structures. Comparison between both approaches suggests similar results and allows us to present the first comprehensive first-order fault-slip-rate estimates for the whole of Iran. Our results confirm most of the results from previous geodetic studies. However, we also show a trade-off between the coupling ratio of the Iranian Makran subduction interface and the kinematics of the faults north of the Makran in the Jazmurian depression. Indeed, although too scarce to accurately estimate a coupling ratio, we show that coupling higher than 0.4 on the plate interface down to a depth of 25 km will induce extension on the E–W faults in the Jazmurian region. However, the sites close to the shoreline suggest a low coupling ratio; hence, the coupling on this plate interface is probably more complicated than previously described and the Iranian Makran subduction interface mechanical behaviour might be similar to that on the Hellenic subduction zone.

Two-degrees-of-freedom piezo-driven fast steering mirror with cross-axis decoupling capability.

Because mechanical cross coupling between its axes would lead to degradation of the scanning precision of a piezo-driven fast steering mirror (PFSM), a two-degrees-of-freedom (2-DoF) PFSM with a cross-axis decoupling capability, in which 2-DoF flexure hinges are used, is proposed in this work. The overall structure of the proposed PFSM is first introduced and then both static and dynamic models are established analytically; in addition, the decoupling mechanism is described in detail and the low dynamic cross coupling ratios that occur between the two DoFs are shown. Because of the decoupling property of the PFSM, the 2-DoF motion is treated as a combination of two independent one-degree-of-freedom (1-DoF) motions and two independent proportional-integral-derivative controllers are thus used separately in the control of the two DoFs. Based on this control strategy, experiments involving both 1-DoF trajectory tracking and 2-DoF trajectory tracking are implemented. The test results show that the proposed PFSM can achieve the tilt range of ±7 mrad for both axes with the low coupling ratios that are less than 2% (-34 dB), and the bandwidths of both axes are higher than 810 Hz; in addition, the maximal tracking full scale range errors for 1-DoF trajectory tracking and 2-DoF trajectory tracking are less than 0.2% and 1%, respectively, where the larger error of 2-DoF trajectory tracking is mainly caused by the remaining cross coupling between axes.

Isolation of native plasma membrane H+-ATPase (Pma1p) in both the active and basal activation states.

The yeast plasma membrane H+‐ATPase Pma1p is a P‐type ATPase that energizes the yeast plasma membrane. Pma1p exists in two activation states: an autoinhibited basal state and an activated state. Here we show that functional and stable Pma1p can be purified in native form and reconstituted in artificial liposomes without altering its activation state. Acetylated tubulin has previously been reported to maintain Pma1p in the basal state but, as this protein was absent from the purified preparations, it cannot be an essential component of the autoinhibitory mechanism. Purification of and reconstitution of native Pma1p in both activation states opens up for a direct comparison of the transport properties of these states, which allowed us to confirm that the basal state has a low coupling ratio between ATP hydrolysis and protons pumped, whereas the activated state has a high coupling ratio. The ability to prepare native Pma1p in both activation states will facilitate further structural and biochemical studies examining the mechanism by which plasma membrane H+‐ATPases are autoinhibited.

Interseismic deformation and moment deficit along the Manila subduction zone and the Philippine Fault system

AbstractWe examine interseismic coupling of the Manila subduction zone and fault activity in the Luzon area using a block model constrained by GPS data collected from 1998 to 2015. Estimated long‐term slip rates along the Manila subduction zone show a gradual southward decrease from 90–100 mm/yr at the northwest tip of Luzon to 65–80 mm/yr at the southern portion of the Manila Trench. We provide two block models (models A and B) to illustrate possible realizations of coupling along the Manila Trench, which may be used to infer future earthquake rupture scenarios. Model A shows a low coupling ratio of 0.34 offshore western Luzon and continuous creeping on the plate interface at latitudes 18–19°N. Model B includes the North Luzon Trough Fault and shows prevalent coupling on the plate interface with a coupling ratio of 0.48. Both models fit GPS velocities well, although they have significantly different tectonic implications. The accumulated strain along the Manila subduction zone at latitudes 15–19°N could be balanced by earthquakes with composite magnitudes of Mw 8.8–9.2, assuming recurrence intervals of 500–1000 years. GPS observations are consistent with full locking of the majority of active faults in Luzon to a depth of 20 km. Inferred moments of large inland earthquakes in Luzon fall in the range of Mw 6.9–7.6 assuming a recurrence interval of 100 years.

Abstract 15031: Defining a Coupling Ratio: Tissue Doppler Velocities in Systole and Diastole Predict Greater Diastolic Than Systolic Impairment in Hypertrophic Cardiomyopathy

Introduction: Mitral annular velocities, E’ and S’, (cm/s) measured by Tissue Doppler Imaging, are used in clinical cardiology and in research as important descriptors of systolic and diastolic function. We hypothesized that the relationship between these velocities in normal individuals would be linear, and would define a ventricular systolic/diastolic coupling ratio. We further hypothesized that departure from this normal coupling ratio might provide insight into certain disease states. Methods: We reviewed consecutive ECHOs performed at our institution to define the coupling ratio in normal individuals (n=57) and in 2 disease states dilated cardiomyopathy (DCM) (n=20), and hypertrophic cardiomyopathy (HCM) (n=19). The average of peak septal and lateral velocities, obtained in systole and diastole were compared (ANOVA). Results: Baseline characters as depicted in the table. In normals, there is a linear relationship between S’ and E’. While the S’ and E’ velocities are lower in absolute terms in DCM, the coupling ratio is similar to that seen in Normals. HCM, by contrast shows a relatively lower coupling ratio than Normals or DCM (Figure attached). Conclusion: We have defined a simple coupling ratio of systolic and diastolic velocities in normal and cardiomyopathy. The greater relative impairment on diastolic velocities in HCM appears to reflect a greater relative impairment in diastolic filling than in systolic shortening. In other words, for a given degree of systolic fiber shortening, fiber lengthening/stretch and perhaps utilization of the Frank Starling mechanism would be disproportionately impaired.

An experimental investigation on decoupling performance for a lateral axis micromachined gyroscope with varying environmental parameters

This paper carries out an experiment study of decoupling performance for a novel lateral axis micromachined gyroscope with varying environmental parameters. The non-ideal mathematical model for the coupling mechanism of the gyroscope is established through the gyro dynamic response matrix. The coupling components varying with ambient pressure and temperature induced by stiffness coupling, damping coupling and electrostatic force coupling are semi-analytically discussed. The overall coupling ratio is evaluated via experiments in the custom-built installation. The testing results show that the decoupling performance of the gyroscope is sensitive to the environmental parameters and all the non-ideal errors are determined as a function of ambient pressure and temperature. The coupling error varies from 0.05% to 0.25% within the pressure range of 100 Pa–100 kPa. The characteristics of coupling with temperature are measured from 20°C to 100°C with a variation from 0.35% to 0.41%. The results also indicate that within the range of measured ambient pressure and temperature, the minimum coupling ratio occurs at 100 Pa and room temperature. The overall performance of the gyroscope is tested under the pressure of about 2000 Pa and room temperature to achieve a relatively low coupling ratio. The scale factor is measured to be 7.8 mV (°) 1 s 1 with nonlinearity about 0.45% in the full-scale range of 600 (°) s 1 . The short-term bias stability is approximately 0.06 (°) s 1 (1  ) for 20 min with noise equivalent angular rate evaluated to be 0.077 (°) s 1 Hz 1/2 .

F1-ATPase: a highly coupled reversible rotary motor

F1 (F1-ATPase) is a highly coupled rotary molecular motor and hydrolyses three ATP molecules per turn (3 ATP/turn). Recently, we have developed femtolitre reaction chamber arrays for highly sensitive measurement of biological reactions. By combining this technique with the rotating magnetic tweezers, the coupling ratio of the reverse reaction, ATP synthesis catalysed by single F1 molecules, has been investigated. The low coupling ratio of 10% (0.3 ATP/turn), catalysed by the alpha3beta3gamma subcomplex of F1, was significantly improved to 77% (2.3 ATP/turn) after reconstitution of the epsilon subunit. This result revealed the novel function of the epsilon subunit as a coupling factor of ATP synthesis catalysed by F1. The possible mechanism for highly coupled ATP synthesis supported by the epsilon subunit is discussed.

An analytical model for optimization of programming efficiency and uniformity of split gate source-side injection superflash memory

An analytical model for evaluating the programming efficiency and uniformity of SST SuperFlash cells is developed for the first time. Starting with a two-dimensional electric field analysis, this model calculates the effective hot electron injection-induced gate current during programming. Based on a full transient simulation of the calculated gate current, the time to program is then developed and used as a figure of merit to evaluate SST cells programming. The time-to-program model predicts the nonlinear transformation from control-floating gate coupling ratios to the programming speed and the programming distribution broadening correlates with coupling ratios. The model also suggests that higher bias voltage of (V/sub d/-V/sub cg/) and a lower coupling ratio should result in better programming efficiency and uniformity.

Characteristics of renal Na(+)-D-glucose cotransport in the skate (Raja erinacea) and shark (Squalus acanthias).

We have investigated the properties of the skate (Raja erinacea) and shark (Squalus acanthias) kidney Na(+)-D-glucose cotransporters (SGLT) in uptake studies of radiolabeled substrates into isolated renal brush-border membrane vesicles (BBMV). Scatchard plot analysis of the substrate dependence revealed that the Na(+)-D-glucose cotransporter population is homogenous within each species. Skate BBMV showed a relatively high affinity for D-glucose [Michaelis constant (K(m)) = 0.12 mM] with an apparent coupling ratio of approximately 2 Na+ to 1 D-glucose, whereas the shark transporter was much lower in affinity (K(m) = 1.90 mM) and had a lower coupling ratio, more like 1 Na+ to 1 D-glucose. These characteristics resemble the properties of SGLT1 and SGLT2, which are known to coexist in the mammalian kidney. Inhibitor studies using sugar analogs and glucosides suggested structural differences of the D-glucose binding site among these transporters, whereas the hydrophobic transporter domains in the vicinity of the D-glucose binding site appeared to be similar. In the high-affinity skate system, D-glucose was recognized by hydrogen bonds to the hydroxy groups at C-2, C-3, and C-4 and by hydrophobic interaction with the C-6 methylene group. In contrast, the low-affinity shark system seemed to lack the hydrophobic recognition motif for the C-6 methylene group of D-glucose.

Enhancement of the antibody response to protein antigens by specific IgG under different experimental conditions.

Specific stimulation of the antibody response to protein antigens by IgG antibodies was studied in vivo. The response to TNP-coupled keyhole limpet haemocyanin (KLH-TNP) was enhanced by a TNP-specific IgG monoclonal antibody, 7B4, as measured both in ELISA (enzyme-linked immunosorbent assay) and by ELISPOT (enzyme-linked immunospot) method. Enhancement was seen when using both high and low doses of antigen and antibody. The antibody response to TNP-coupled bovine serum albumin (BSA-TNP), but not to TNP-coupled ovalbumin (OA-TNP), tetanus toxoid (TT-TNP) or diphtheria toxoid (DT-TNP), was also efficiently augmented by 7B4. Enhancement was seen when using both high and low coupling ratio of TNP to KLH. The fact that IgG-mediated enhancement is seen under many different experimental conditions suggests that it is a physiologically relevant phenomenon. In order to enhance the response to KLH-TNP and BSA-TNP, 7B4 had to be injected while antigen was circulating in blood. This supports that IgG-mediated stimulation acts by concentrating circulating antigen into lymphoid centres.