Frustrated spin ladder with alternating spin-1 and spin-1/2 rungs

We study the impact of the diagonal frustrating couplings on the quantum phase diagram of a two-leg ladder composed of alternating spin-1 and spin-1/2 rungs. As the coupling strength is increased the system successively exhibits two gapped paramagnetic phases (a rung-singlet and a Haldane-like non-degenerate states) and two ferrimagnetic phases with different ferromagnetic moments per rung. The first two states are similar to the phases studied in the frustrated spin-1/2 ladder, whereas the magnetic phases appear as a result of the mixed-spin structure of the model. A detailed characterization of these phases is presented using density-matrix renormalization-group calculations, exact diagonalizations of periodic clusters, and an effective Hamiltonian approach inspired by the analysis of numerical data. The present theoretical study was motivated by the recent synthesis of the quasi-one-dimensional ferrimagnetic material Fe$^{II}$Fe$^{III}$ (trans-1,4-cyclohexanedicarboxylate) exhibiting a similar ladder structure.Comment: 10 pages, 8 figure

Renormalization group study of the Kondo problem at a junction of several Luttinger wires

We study a system consisting of a junction of N quantum wires, where the junction is characterized by a scalar S-matrix, and an impurity spin is coupled to the electrons close to the junction. The wires are modeled as weakly interacting Tomonaga-Luttinger liquids. We derive the renormalization group equations for the Kondo couplings of the spin to the electronic modes on different wires, and analyze the renormalization group flows and fixed points for different values of the initial Kondo couplings and of the junction S-matrix (such as the decoupled S-matrix and the Griffiths S-matrix). We generally find that the Kondo couplings flow towards large and antiferromagnetic values in one of two possible ways. For the Griffiths S-matrix, we study one of the strong coupling flows by a perturbative expansion in the inverse of the Kondo coupling; we find that at large distances, the system approaches the ferromagnetic fixed point of the decoupled S-matrix. For the decoupled S-matrix with antiferromagnetic Kondo couplings and weak inter-electron interactions, the flows are to one of two strong coupling fixed points in which all the channels are strongly coupled to each other through the impurity spin. But strong inter-electron interactions, with K_\rho < N/(N+2), stabilize a multi-channel fixed point in which the coupling between different channels goes to zero. We have also studied the temperature dependence of the conductance at the decoupled and Griffiths S-matrices.Comment: Revtex4, 16 pages including 6 figure

Effect of Molar Concentration on Optical Absorption Spectra of ZnS:Mn Nanoparticles

The present paper reports the synthesis and characterization of luminescent nanocrystals of manganese doped zinc sulphide. Nanocrystals of zinc sulphide were prepared by chemical precipitation method using the solution of zinc chloride, sodium sulphide, manganese chloride and mercaptoethanol was used as the capping agent. It was found that change in the molar concentration changes the particle size. The particle size of such nanocrystals was measured using XRD pattern and it is found to be in between 3 nm – 5 nm. The blue-shift in absorption spectra was found with reducing size of the nanoparticle

Design and Development of Two Wheel Drive Track Spy Robot with Night Vision Camera

The design and development of a 2-wheel drive track spy robot arise from the increasing demand for advanced surveillance systems in various domains such as military operations, security applications, and exploration missions. There is a need for a compact and agile robot that can navigate challenging terrains, gather visual and auditory information discreetly, and transmit data in real-time. The existing surveillance technologies often face limitations in terms of mobility, stealth, and adaptability to diverse environments. The two-wheel drive track spy robot aims to overcome these limitations by leveraging the advantages of a compact, track-based design. This enables enhanced manoeuvrability over rough surfaces, noise reduction, and the ability to traverse obstacles efficiently. By designing and developing a 2-wheel drive track spy robot, it is expected to provide a cost-effective and versatile solution for surveillance and reconnaissance applications. The resulting system will enable improved situational awareness, reduced risks to human operators, and enhanced operational capabilities in both civilian and military scenarios

Localized-magnon states in strongly frustrated quantum spin lattices

Recent developments concerning localized-magnon eigenstates in strongly frustrated spin lattices and their effect on the low-temperature physics of these systems in high magnetic fields are reviewed. After illustrating the construction and the properties of localized-magnon states we describe the plateau and the jump in the magnetization process caused by these states. Considering appropriate lattice deformations fitting to the localized magnons we discuss a spin-Peierls instability in high magnetic fields related to these states. Last but not least we consider the degeneracy of the localized-magnon eigenstates and the related thermodynamics in high magnetic fields. In particular, we discuss the low-temperature maximum in the isothermal entropy versus field curve and the resulting enhanced magnetocaloric effect, which allows efficient magnetic cooling from quite large temperatures down to very low ones.Comment: 21 pages, 10 figures, invited paper for a special issue of "Low Temperature Physics " dedicated to the 70-th anniversary of creation of concept "antiferromagnetism" in physics of magnetis

Antiferromagnetic sawtooth chain with spin-½ and spin-1 sites

We study the low-energy properties of a sawtooth chain with spin-1's at the bases of the triangles and spin-½'s at the vertices of the triangles. The spins have Heisenberg antiferromagnetic interactions between nearest neighbors, with a coupling J2 between a spin-1 and a spin-½, and a coupling J1=1 between two spin-1's. Analysis of the exact diagonalization data for periodic chains containing up to N=12 unit cells shows that the ground state is a singlet for exchange couplings up to approximately J2=3.8, whereas for larger J2 the system exhibits a ferrimagnetic ground state characterized by a net ferromagnetic moment per unit cell of ½. In the region of small interactions J2, the mixed spin sawtooth chain maps on to an effective isotropic spin model representing two weakly interacting and frustrated spin-½ Heisenberg chains composed of spin-½ sites at odd and even vertices, respectively. Finally, we study the phenomenon of a macroscopic magnetization jump which occurs if a magnetic field is applied with a value close to the saturation field for J2=2

Strategies Towards the Synthesis of Staurosporine Indolocarbazole Alkaloid and Its Analogues

In this Chapter we revisit the main strategies used for years in synthesizing staurosporine indolocarbazole alkaloid and its analogues, which are promising compounds for treating cancer. In addition to describing the details of the synthesis strategies, including the key challenges that had to be faced, we offer a historical perspective of the development in the field

An Efficient Breast Cancer Detection Using Machine Learning Classification Models

Breast cancer is still a dangerous and common disease that affects women all over the world, which highlights how crucial early identification is to better patient outcomes. In recent years, utilizing machine learning (ML) algorithms has improved accuracy and efficiency dramatically in a variety of applications, showing promising outcomes. This article provides a novel machine-learning approach to increase the accuracy of breast cancer detection. To improve diagnostic efficiency and accuracy, our suggested methodology combines sophisticated feature selection strategies, reliable classification algorithms, and enhanced model training methodologies. We investigated several ML classifiers, and after thorough hyperparameter tuning, the models were. Random forest and gradient boosting have achieved the highest performance with an accuracy of 97.90% and an ROC score of 0.99. This research highlights the effectiveness of ML, particularly the random forest algorithm, in breast cancer diagnosis and prognosis. Future work may explore deep learning techniques for determining the disorder’s severity

Analgesic and anti-inflammatory properties of the aqueous extract leaves of Murraya koenigii linn in small animal models

Background: The present study was carried out to evaluate the analgesic activity of aqueous extract leaves of Murraya koenigii linn in Albino rats using tail flick method, Eddy’s hot plate methods and anti-inflammatory activity in Carrageenan induced paw edema in rats.Methods: The analgesic activity was evaluated using Eddy’s hot plate induced hyperalgesia and tail flick method, which served as thermal induced pain, where the animal were placed on the hot plate and the reaction time to (lick the paw/jump out) from the hot plate was observed, 0, 30, 60, 90 mins. Murraya 300 mg, 600 mg/kg/body weight (BW) and ibuprofen (5 mg/kg BW) was administered per oral. The anti-inflammatory activity was measured by Carrageenan induced paw edema volumes at 0, 1, 2, 3 and 4 hrs using mercury plethysmometer, which served as chemical induced pain models.Results:  The mean reaction time in Murraya at a dose of 600 mg/kg at 0 min 5.45±0.72, at 30 mins 6.52±1.03, at 60 mins 7.6±0.81, at 90 mins 8.8±0.63 respectively. The mean reaction time increased significantly with Murraya at dose of 600 mg/kg when compared with control.In the ibuprofen group, the mean reaction time at 0 hr was 0.28±0.04, at 1 hr 0.34±0.05, at 2 hrs 0.46±0.03, at 3 hrs 0.61±0.05, at 4 hrs 0.76±0.05. The mean reaction time Murraya in group 600 mg/kg at 0 hr 0.27±0.04, at 1 hrs 0.39±0.03, at 2 hrs 0.48±0.06, at 3 hrs 0.68±0.05, at 6 hrs 0.80±0.03, respectively.Conclusions: The results indicate that the aqueous extract of Murraya (leaf) extract revealed significant analgesic and anti-inflammatory in thermal and chemical induced pain models