Triangular Dot Research Articles

595. The Effect of Herpes Zoster Vaccination on New Diagnoses of Dementia: A Quasi-randomized Study in Australia

Abstract Background We have recently provided evidence from a quasi-randomized study in Wales that herpes zoster (HZ) vaccination reduced the incidence of new dementia diagnoses. This study used a similar quasi-randomization in Australia to determine the effect of HZ vaccination on new dementia diagnoses over 7.5 years.Figure 1:Eligibility for a free herpes zoster (HZ) vaccine reduces dementia diagnosesIn panel (a), a regression discontinuity is plotted, where the forcing variable is the number of weeks from the cutoff (November 2, 1936) and the outcome is dementia diagnoses (in percentages). The triangular dots indicate dementia diagnoses for the comparison group, scaled up by the intercept for the main cohort. Panel (b) describes this effect for different follow-up periods, and panel (c) shows the effect for different grace periods. Methods In Australia, starting on November 1 2016, live-attenuated HZ vaccination was provided for free to individuals aged 70 to 79 years of age. Thus, those whose 80th birthday was just a few days prior to November 1 2016 never became eligible, whereas those whose 80th birthday was a few days later were eligible for one year. There is no reason to expect that these population groups who differ in their age by only a minute degree should differ in any of their dementia-related characteristics. We used detailed primary healthcare records (provided by PenCS) with week-of-birth information from 65 general practices across Australia. We analyzed our data using a comparative regression discontinuity design, with dementia diagnoses from older birth cohorts serving as a comparison group. Results Of 108,670 patients in our data, 15,297 were born between November 2 1928 and November 2 1944. At baseline, patients were well-balanced across the date-of-birth eligibility threshold (November 2 1936) for HZ vaccination in their preventive health services uptake and chronic disease diagnoses. There was an abrupt increase of 13.2 (95% CI: [8.7, 17.6], p = 0.001) percentage points in the probability of ever receiving HZ vaccination between patients born shortly before versus shortly after the eligibility threshold. Eligibility for a free HZ vaccination caused a 3.9 percentage point (95% CI: [1.7, 6.1], p = 0.001) decrease in the probability of receiving a new dementia diagnosis over 7.5 years. Being eligible for HZ vaccination did not affect the probability of taking up other preventive health services (including other vaccinations) nor do we find consistent evidence that it affected the probability of receiving any of the twenty most common disease diagnoses in our data. Conclusion In conjunction with our findings from Wales, these results from Australia constitute robust evidence that live-attenuated HZ vaccination may delay or prevent dementia. Disclosures All Authors: No reported disclosures

Room Temperature Synthesis of Hydrogen Permeation Barrier for Storage and Transportation Application

Distribution of hydrogen in future hydrogen-based economy requires a dense pipeline network for its safe delivery. Natural take is to consider the existing networks of natural gas (NG) infrastructure. However, the main issue is that hydrogen-embrittlement on NG pipes’ steels significantly reduces their fracture toughness and threatens their structural integrity1. Besides developing a new grade of steels less susceptible to the embrittlement, effective hydrogen permeation barriers (HPBs) remain important solution for re-purposing of the existing NG infrastructure for hydrogen transport. Besides a few specific metals, candidates are some oxides,carbides, and nitrides. These coatings require extreme conditions for their synthesis, which renders their application impractical.We employed strategy for HPB synthesis based on electroless Cu-deposition process2. We have employ solution chemistries exploring a wide range of reducing agents. These include formaldehyde, glyoxylic acid, Na2HPO2 ... and others. Variety of complexing agents were considered as well; EDTA, sodium citrate, sodium potassium tartarate and others. Our optimum solution design favored a large driving force for Cu reduction providing high nucleation rates and films with fewer defects and dense grain boundaries. The comparative analysis between hydrogen permeation rates through bare steel samples and steel samples coated with Cu HPB films is performed using Devanathan - Stachurski permeation technique3. The Cu-HPB thickness varied from experiment to experiment. More than 30 samples have been evaluated. An integral example of these measurements is shown in Figure 1. Permeation reduction factor (PRF) for Cu-HPB as a function of the ratio between steel and Cu-HPB thickness is shown against theoretical calculations. Our results exceed theoretical predictions by factor of 2-5. Figure 1: Calculations for PRF of Cu/(AISI 4340 steel) as a function of ds/df ratio. Square, circular, and triangular dots represent PRF measurements for Cu-HPB/(ASTM A36 steel) samples produced from tartaric acid (TA) and EDTA solutions. Insets show optical images of steel and Cu/steel samples (left) and SEM of Cu surface morphology (right).

Fluorescence immunoassay using triangular carbon dots for detection of the cardiac marker Troponin T in acute myocardial infarction

A cardiac immunosensor was developed to detect heart attacks (myocardial infarctions) at an early stage. This technique, utilizing carboxylic functionalized triangular carbon dots (caf-TCDs) combined with an antibody anti-cardiac Troponin T (anti-cTnT), proved to be a quick and sensitive method for detecting cardiac troponin T (cTnT) in both buffer solutions and biological fluids such as serum. The antibody for cardiac Troponin T (cTnT) was chemically linked to amphiphilic caf-TCDs using a carbodiimide coupling reaction. Exfoliated graphene oxide (GO) sheets effectively bind to anti-cTnT labeled caf-TCDs on their surface, resulting in a non-radiative energy transfer process where the fluorescence is suppressed. This interaction between caf-TCDs and GO follows a nonlinear and increasing Stern-Volmer relationship, indicating a combination of static and dynamic quenching. When antigen (cTnT) is present, the interaction between antibodies (anti-cTnT) and the cTnT molecules hinders the energy transfer process. This interaction also affects the positioning of the nano-couple and causes the detachment of CDs from the GO surface. As a result, the energy transfer process is impeded, leading to the restoration of fluorescence intensity. The sensor exhibits high specificity and low sensitivity to non-specific antigens. It shows a linear reaction to cTnT in the range of 0.05–50 ng mL-1, with a detection limit of 0.046 ng mL-1. Therefore, the anti-cTnT-caf-TCD/GO sensor offers a potential platform for detecting cTnT with increased sensitivity.

Distributed visual positioning for surgical instrument tracking.

In clinical operations, it is crucial for surgeons to know the location of the surgical instrument. Traditional positioning systems have difficulty dealing with camera occlusion, marker occlusion, and environmental interference. To address these issues, we propose a distributed visual positioning system for surgical instrument tracking in surgery. First, we design the marker pattern with a black and white triangular grid and dot that can be adapted to various instrument surfaces and improve the marker location accuracy of the feature. The cross-points in the marker are the features that each feature has a unique ID. Furthermore, we proposed detection and identification for the position-sensing marker to realize the accurate location and identification of features. Second, we introduce multi Perspective-n-Point (mPnP) method, which fuses feature coordinates from all cameras to deduce the final result directly by the intrinsic and extrinsic parameters. This method provides a reliable initial value for the Bundle Adjustment algorithms. During instrument tracking, we assess the motion state of the instrument and select either dynamic or static Kalman filtering to mitigate any jitter in the instrument's movement. The core algorithms comparison experiment indicates our positioning algorithm has a lower reprojection error comparison to the mainstream algorithms. A series of quantitative experiments showed that the proposed system positioning error is below 0.207mm, and the run time is below 118.842ms. The results demonstrate the tremendous clinical application potential of our system providing accurate positioning of instruments promoting the efficiency and safety of clinical surgery.

백제 사비기 왕궁과 사원의 기와 수급 방식과 와공의 동향

The purpose of this study is to shed light on the differences in the production and distribution of ceramic roof tiles used in the construction of the royal palaces and Buddhist temples of Baekje in the Sabi period (538-660) and the changes that occurred in the activities of the tile makers.The discussion in Chapter 2 is focused on the differing ways in which ceramic roof tiles were used in the construction of royal palaces and temples during the Sabi Baekje period. The convex roof-end tiles excavated at the sites of Baekje’s royal palaces, including those at Busosanseong Fortress, Archaeological Site in Gwanbuk-ri, Gua-ri and Ssangbuk-ri Buyeo, shared similar decorative motifs such as circular and triangular dots and waves for a long period of time. Conversely, the convex roof-end tiles discovered at temple sites dating back to the Sabi Baekje period, such as Temple Sites in Neungsa-ri and Gunsu-ri, and Wangheungsa Temple Sie in Buyeo, and Jeseoksa and Mireuksa Temples in Iksan, show that more than two new motifs were introduced at that time. The difference can be explained by the fact that new buildings continued to be added to the royal palaces, making necessary stricter management and control of the tile manufacturing facilities and equipment.In Chapter 3, the discussion deals with the ways in which roof tiles were produced and distributed for the construction of royal palaces and temples and the tendencies of tile makers. The roof tiles of new Buddhist temples built during the Sabi period were supplied by both state-run kilns and private kilns specializing in the production of roof tiles for Buddhist temples. The construction of palace buildings in the Sabi period led to continuous growth inthe size and number of tile kilns, as can be seen in the kiln sites at Geumdeok-ri, Jeongam-ri, Jeongdong-ri, Wangjin-ri and Hyeonbuk-ri. The discoveries made at the Yeondong-ri kiln site in Iksan suggest that the tile makers hired by the government-run workshops in Buyeo produced the roof tiles required for construction projects in the Iksan area. The excavation of the Wangheungsa Temple kiln site has revealed that the operator of the kiln organized temporary teams of tile makers from among workers at other kilns, suggesting a turning point in the history of tile production in Baekje. Analysis of the archaeological features has also revealed that the tile kilns of Wangjin-ri, Gwanhyeon- ri and Bonui-ri in Cheongyang were created by tile makers who had previously worked at the larger, government-financed kilns in Jangam-ri and Geumdeok-ri in Seocheon. The appearance of the convex roof-end tiles discovered at the kiln sites in Sinsan-ri of Seosan, Bunhyang-ri of Cheongyang, Sudeoksa Temple in Yesan, and Cheonho-ri of Nonsan suggests that they were produced by tile makers sent from the government-run kilns in the capital of Baekje for short-term local projects. Such changes in Baekje’s tile production system resulted from the effort to meet the need for a new system to ensure the mass production of roof tiles, effectively meeting the rapidly growing demand related with the construction of the fortified capital of Sabi in the late sixth century.

Edge spin wave transmission through a vertex domain wall in triangular dots

Spin waves (SWs), being usually reflected by domain walls (DWs), could also be channeled along them. Edge SWs yield the interesting, and potentially applicable to real devices property of broadband spin wave confinement to the edges of the structure. Here, we investigate through numerical simulations the propagation of quasi one-dimensional spin waves in triangle-shaped amorphous YIG (Y3Fe5O12) micron sized ferromagnets as a function of the angle aperture. The edge spin waves (ESWs) have been propagated over the corner in triangles of 2 microns side with a fixed thickness of 85 nm. Parameters such as superior vertex angle (in the range of 40^circ –75^circ ) and applied magnetic field have been optimized in order to obtain a higher transmission coefficient of the ESWs over the triangle vertex. We observed that for a certain aperture angle for which dominated ESW frequency coincides with one of the localized DW modes, the transmission is maximized near one and the phase shift drops to pi /2 indicating resonant transmission of ESWs through the upper corner. We compare the obtained results with existing theoretical models. These results could contribute to the development of novel basic elements for spin wave computing.

Quantum simulator of extended bipartite Hubbard model with broken sublattice symmetry: Magnetism, correlations, and phase transitions

We describe here a quantum simulator of extended bipartite Hubbard model with broken sublattice symmetry. The simulator consists of a structured lateral gate confining two dimensional electrons in a quantum well into artificial minima arranged in a hexagonal lattice. The sublattice symmetry breaking is generated by forming an artificial triangular graphene quantum dot (ATGQD) with zigzag edges. The resulting extended Hubbard model generates tunable ratio of tunneling strength to electron-electron interactions and of sublattice symmetry with control over shape. The validity of the simulator is confirmed for small systems using mean-field and exact diagonalization many-body approaches which show that the ground state changes from a metallic to an antiferromagnetic (AF) phase by varying the distance between sites or depth of the confining potential. The one-electron spectrum of these triangular dots contains a macroscopically degenerate shell at the Fermi level. The shell persists at the mean-field level for weak interactions (metallic phase) but disappears for strong interactions, in the AF phase. We determine the effects of electron-electron interactions on the ground state, the total spin, and the excitation spectrum as a function of filling of the ATGQD. We find that the half-filled charge neutral shell leads to a partially spin polarized state in both metallic and AF regimes in accordance with Liebs theorem. In both regimes a relatively large gap separates the spin polarized ground state to the first excited many-body state at half filling of the degenerate shell. By adding or removing an electron, this gap drops dramatically, and alternate total spin states emerge with energies nearly degenerate to a spin polarized ground state.

Impact of arsenic species on self-assembly of triangular and hexagonal tensile-strained GaAs(111)A quantum dots

We use dimeric arsenic (As2) or tetrameric arsenic (As4) during molecular beam epitaxy to manipulate the structural and optical properties of GaAs(111)A tensile-strained quantum dots (TSQDs). Choice of arsenic species affects nucleation and growth behavior during TSQD self-assembly. Previously, epitaxial GaAs(111)A TSQDs have been grown with As4, producing TSQDs with a triangular base, and ‘A-step’ edges perpendicular to the three directions. We demonstrate that using As2 at low substrate temperature also results in triangular GaAs(111)A TSQDs, but with ‘B-step’ edges perpendicular to the three directions. We can therefore invert the crystallographic orientation of these triangular nanostructures, simply by switching between As4 and As2. At higher substrate temperatures, GaAs(111)A TSQDs grown under As2 develop with a hexagonal base. Compared with triangular dots, the higher symmetry of hexagonal TSQDs may reduce fine-structure splitting on this (111) surface, a requirement for robust photon entanglement. Regardless of shape, GaAs(111)A TSQDs grown under As2 exhibit superior optical quality.

Standing spin waves in perpendicularly magnetized triangular dots

Standing spin waves in triangular dots (truncated pyramids) were investigated both experimentally and theoretically. Arrays of nickel triangular pyramids with the base side of 270 nm and height of 70 nm were deposited on Si (111) substrate. The spectra of ferromagnetic resonance were obtained at room temperature with an external saturating magnetic field directed perpendicular to the array plane. The theoretical approach, which allows to describe standing spin wave modes both in perpendicular magnetized regular prisms and in close to prisms truncated pyramids, was developed. Theoretically calculated resonance fields for the observed modes are in a good correlation with the experiment.

Suppression of Leakage for a Charge Qubit in Triangular Triple Quantum Dots

AbstractThis paper presents a simple yet effective strategy to suppress the leakage in a three‐quantum‐dot charge qubit system by having the dots in a triangle as opposed to the linear geometry commonly conceived. It is found that the tunnel coupling between the two outmost dots is amplified in triangular triple dots, which consequently reduces leakage by separating the leaked state and qubit states. It has been found that the leakage can be suppressed by as much as five orders of magnitude when the dots form an equilateral triangle, with further improvement of control fidelities possible if composite pulses are applied.

Single-particle energy – and optical absorption – spectra of multilayer graphene quantum dots

The energy spectra of quantum dots formed by stacked disks of graphene are calculated as a function of the disk shape and size, the number of disk layers and the edge type (zigzag /armchair) within a tight-binding approach in the single-particle picture. Stacks formed by up to seven disks of hexagonal, rhombic and triangular shape are considered. For both edge types, we find a monotonously decreasing energy gap as the number of stacked disks or the disk size is increased, with the exception of triangular dots with zigzag edges, which have a metallic character. In some cases, simple scaling relations for the energy gaps can be formulated. Furthermore, the optical absorption spectra within the dipole approximation are calculated. The results are interpreted with the help of selected HOMO wave functions that form inside the stacks. • The densities of states of multilayer graphene quantum dots of different shapes (GQDs) are calculated. • Graphene quantum dots with up to seven layers are considered. • The corresponding optical absorption spectra are computed. • Zigzag and armchair multilayer dots show strong differences in the energy gaps. • The limit of infinitely many layers is computed for both types of edges.

Engineering Zero-Dimensional Quantum Confinement in Transition-Metal Dichalcogenide Heterostructures.

Achieving robust, localized quantum states in two-dimensional (2D) materials like graphene is desirable for optoelectronics and quantum information yet challenging due to the difficulties in confining Dirac fermions. Traditional colloidal nanoparticle and epitaxially grown quantum dots are also impractical for solid-state devices, due to either complex surface chemistry, unreliable spatial positioning, or lack of electrical and optical access. In this work, we design and optimize nanoscale monolayer transition-metal dichalcogenide (TMD) heterostructures to natively host massive Dirac fermion bound states. We develop an integrated multiscale approach to translate first-principles electronic structure to higher length scales, where we apply a continuum model to consider arbitrary 2D quantum dot geometries and sizes. Focusing on a model system of an MoS2 quantum dot in a WS2 matrix (MoS2/WS2), we find discrete bound states in triangular dots with side lengths up to 20 nm. We propose figures of merit that, when optimized for, result in heterostructure configurations engineered for maximally isolated bound states at room temperature. These design principles apply to the entire family of semiconducting TMD materials, and we predict 6.5 nm MoS2/WS2 (quantum dot/matrix) triangular dots and 4.5 nm MoSe2/WSe2 triangular dots as ideal systems for confining massive Dirac fermions.

Effects of nanodots shape and lattice constants on the spin wave dynamics of patterned permalloy dots

Micromagnetic simulations studies on Permalloy (Ni80Fe20) nanodots with different shapes and edge-to-edge separations (s) down to 25nm arranged in square lattice are reported. We observe the significant variation of spin-wave (SW) dynamics of nanodots of different shapes (triangular, diamond and hexagon) and of fixed dot diameter 100nm with varying s. Modes for single dot are transformed in an array into multiple quantized, edge and centre modes for different shapes and edge-to-edge separations, with different spin wave frequencies and peak intensities. Specifically, in the triangular dot sample, a broad range of mode frequencies is observed with highest SW frequency 14.7 GHz. For separation less than 100nm, the SW frequencies undergoes significant modification due to the varying nature of the magnetostatic and dipolar interaction in the array while for separations above 100nm, the SW frequency mostly remain constant. The power profiles confirm the nature of the observed modes. The spatial profiles of magnetostatic field are determined by a combination of internal magnetic-field profiles within the nanodots and the magnetostatic fields within the lattice. The inter-dots interaction of magnetostatic field shows dipolar and quadrupole contributions for all the shapes. Interestingly, vortex states with shifted core and polarity are observed in the array for all the shapes at Hbias = 0. Our results provide important understanding about the tunability of SW spectra in the array of triangular, diamond and hexagon shaped nanoelements.

Energy spectrums of bilayer triangular phosphorene quantum dots and antidots

We theoretically investigate the confined states of the bilayer triangular phosphorene dots and antidots by means of the tight-binding approach. The dependence of the energy levels on the size, the type of the boundary edges, and the orientation of the dots and antidots, and the influences of the electric and magnetic fields on the energy levels, are all completely analyzed. It is found that the energy level numbers of the bilayer dots and antidots are determined by the energy levels in two layers. The external electric field can effectively tune the energy levels of the edge states in both layers to move in opposite directions. With the increase of the magnetic field, the magnetic energy levels can approach the Landau levels of the phosphorene monolayer, the phosphorene bilayer, or both, depending on the specific geometry of the monolayer-bilayer hybrid phosphorene quantum dots. This research should be helpful for the overall understanding of the electronic properties of the multilayer hybrid phosphorene nanostructures and designing the corresponding phosphorene devices.

Strongly Correlated Effects in a Triangular Dot System Induced by Inter-Dot Hopping and Coulomb Repulsion

We study the transport property and the phase transition for a triple quantum dot system in a triangular geometry with one centered dot and two side dots by adopting the Wilson’s numerical renormalization group method. When three dots are decoupled with no coupling, the Kondo peak turns to reach the unitary limit, and the spin-1/2 Kondo effect is found. When the hopping between the centered dot and two side dots increases, two side dots form a local spin triplet due to the Ruderman–Kittel–Kasuya–Yosida interaction mediated by the centered dot, and the Kondo peak is suppressed. As the hopping between two side dots increases, a first order quantum phase transition occurs. In this case, two side dots form a spin singlet and the Kondo peak is recovered. When the inter-dot Coulomb repulsion between two side dots is taken into account and the hopping between two side dots is small, the charge on each side dot drops to 0.5 through a first-order quantum phase transition. As a result, one of the side dots is singly occupied, while the other one is empty. The linear conductance is suppressed due to the strong coupling between the centered dot and the singly occupied side dot. When the hopping between two side dots is large enough, the charge on each side dot decreases to 0.5 continuously and a crossover is found, for in this case the symmetry of spin configurations within two side dots is broken.

Patterning of Nanoparticle Arrays by Self-assembly Lithography

Nanoparticle arrays have been patterned using sub-micron sphere self-assembly lithography technique. 2D crystal self-assembled closed-packed monolayer of polystyrene spheres were formed and used as deposition masks. Nanoparticle arrays of hexagonal lattice of triangular dots were created by sputtering metal thin films through the sub-micron sphere mask. The mask was lifted off by sonication with tetrahydrofuran (THF). The metal thin films deposited through the interstitial areas forms the arrays of triangular elements. Structural characteristic including size and shape was performed by scanning electron microscope (SEM). The effect of sputtering power and polystyrene sphere sizes on the nanoparticle arrays was explored.

Optical properties of geometrically optimized graphene quantum dots

We derive effective tight-binding model for geometrically optimized graphene quantum dots and based on it we investigate corresponding changes in their optical properties in comparison to ideal structures. We consider hexagonal and triangular dots with zigzag and armchair edges. Using density functional theory methods we show that displacement of lattice sites leads to changes in atomic distances and in consequence modifies their energy spectrum. We derive appropriate model within tight-binding method with edge-modified hopping integrals. Using group theoretical analysis, we determine allowed optical transitions and investigate oscillatory strength between bulk–bulk, bulk–edge and edge–edge transitions. We compare optical joint density of states for ideal and geometry optimized structures. We also investigate an enhanced effect of sites displacement which can be designed in artificial graphene-like nanostructures. A shift of absorption peaks is found for small structures, vanishing with increasing system size.

Highly Sensitive Homogeneous Immunoassays Based on Construction of Silver Triangular Nanoplates-Quantum Dots FRET System.

With growing concerns about health issues worldwide, elegant sensors with high sensitivity and specificity for virus/antigens (Ag) detection are urgent to be developed. Homogeneous immunoassays (HIA) are an important technique with the advantages of small sample volumes requirement and pretreatment-free process. HIA are becoming more favorable for the medical diagnosis and disease surveillance than heterogeneous immunoassays. An important subset of HIA relies on the effect of fluorescence resonance energy transfer (FRET) via a donor-acceptor (D–A) platform, e.g., quantum dots (QDs) donor based FRET system. Being an excellent plasmonic material, silver triangular nanoplates (STNPs) have unique advantages in displaying surface plasmon resonance in the visible to near infrared spectral region, which make them a better acceptor for pairing with QDs in a FRET-based sensing system. However, the reported STNPs generally exhibited broad size distributions, which would greatly restrict their application as HIA acceptor for high detection sensitivity and specificity purpose. In this work, uniform STNPs and red-emitting QDs are firstly applied to construct FRET nanoplatform in the advanced HIA and further be exploited for analyzing virus Ag. The uniform STNPs/QDs nanoplatform based medical sensor provides a straightforward and highly sensitive method for Ag analysis in homogeneous form.

Direct observation of magnetic vortex behavior in an ordered La0.7Sr0.3MnO3 dot arrays.

Directly observing the magnetic domain behavior in patterned nanostructures is crucial to the investigation into advanced spin-based devices. Herein, we show that the magnetic vortex behavior can be deterministically observed and controlled in highly spin polarized La0.7Sr0.3MnO3 (LSMO) triangular dots by successive in-field magnetic force microscopy (MFM). Imaging the magnetic domains with MFM shows that most of the LSMO dots exhibit magnetic vortex states with a clockwise or anticlockwise "pinwheel" structure for decreasing the demagnetization energy. Probing the vortex chirality using in-field MFM indicates that the selective spin circulation of the triangular dots depends on the magnetic orientation of the bias nanomagnet with specially designed geometries. Comparison between measurement and simulation reveals that the vortex behavior should be governed by an interface involved pinning strength at the boundaries, as well as a geometrically induced shape anisotropy of the triangular dot, both of which result in shape-dominated magnetic domain reversals.

Phase diagram and low temperature scenario for a triangular triple dot system

We present a triangular triple quantum dot (TTQD) system with two dots connected parallelly to one conduction lead, and investigate the phase diagram, the electric transport, and the temperature-dependent magnetic moment at half filling. When the hopping between two connected dots t12 = 0, and those between the connected dots and the side dot are symmetric t13 = t23, two connected dots form a spin triplet due to the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction mediated by the dot-lead coupling and/or the hopping t13 (t23). For t13 = 0, the triplet is partially screened by the conduction leads at low temperature. Both the connected dots and the side dot contribute to the magnetic moment of the system. For any definite t13, the triplet is totally screened by the conduction leads and the side dot, and the two-stage Kondo effect occurs. When t12 increases beyond a critical t12c, two connected dots form a spin singlet and decouple from the side dot. In this case, the Kondo peak is strongly suppressed, indicating zero conductance, and only the localized side dot contribute to the magnetic moment at low temperature. When t13 ≠ t23, we find a crossover as t12 increases, contrast to the first order transition of the symmetric case. Numerical renormalization group technique and physical arguments are used to obtain a detailed understanding of these problems.