•Cluster-glass behavior in Ca3Co2O6 and its substituents.•Large relaxation time.•Procedure for detection of softness/hardness of ferromagnetic material whose transition lies at non-zero field.
We ...report the structural and magnetic properties of Ca3-xDyxCo2O6 (x = 0, 0.1, 0.2, and 0.3). We found evidence of Cluster-glass (CG)-like freezing phenomena in these samples. The isothermal magnetization curve depicts step-like change indicative of the first-order transition, which decreases with the increase of substitution. The Brillouin function was used to determine the ‘spins’, participating at this first-order transition J12→J32. Relaxation measurements revealed the existence of short-range Cluster-glass-like behavior. Analyzing the results using Vogel-Fulcher law shows that the Vogel-Fulcher temperature (T0) and the relaxation time is around 10 K and 104 s, respectively.
A calcium-chitosan-triazole nanocomplex (Ca@CS-Tz) was synthesized via the robust copper catalyzed azide-alkyne cycloaddition using calcium carbide (CaC2) as an in-situ source of acetylene. The ...nanocomplex was characterized by various techniques and it was proved to be an efficient drug carrier with satisfactory antimicrobial and antioxidant properties. Quercetin loaded nanocomplex (encapsulation efficiency- 68.2 ± 1.0 %) was studied for targeted drug release and the drug release after 120 h was found to be 80.7 ± 0.8 % and 8.69 ± 0.5 % at pH 5.0 and 7.4 respectively. On biological evaluation, the nanocomplex showed enhanced antimicrobial activity against gram-negative bacteria Escherichia coli (E. coli), gram-positive bacteria Bacillus subtilis (B. subtilis) and a fungi Aspergillus niger (A. niger). Moreover, the synthesized Ca@CS-Tz nanocomplex also exhibited significant antioxidant property. Herein, the novel results corresponding to the antimicrobial effect on A. niger and drug delivery studies performed using our previously synthesized chitosan triazole (CS-triazole) derivative have also been reported. Finally, the results of the present study were compared to the results obtained to our previously reported derivative. The incorporation of calcium ions into CS-triazole can lead to the utilization of this complex in various other biomedical applications e.g. bone tissue engineering.
•Review on modeling aspects of greenhouse models.•Information on working principles with heat and mass balance equations.•Formulation of the generalized procedure for thermal model ...development.•Concluding remarks with suggestions for further studies.
Modeling of greenhouse microclimate is very important to maintain optimum inside environment during different stages of plant growth. To formulate an accurate thermal model, computation of precise solar radiation input and overall heat transfer coefficient is important as these affect the greenhouse energy and mass balance. Initially, we briefly review the modular studies related to solar radiation capture and overall heat transfer coefficient for greenhouse applications. Numerous thermal models have been developed to describe the microclimate of a greenhouse and validated at various locations, climates and crops. We review all these independent thermal models (static as well as dynamic) and discuss in detail the representative ones. In adverse winter climatic conditions, greenhouse has to be coupled with various active or passive heating systems to maintain the inside microclimate according to crop needs. We also review greenhouse thermal models integrated with heating/heat storage systems such as: rock-bed, phase change materials, earth-tube heat exchanger systems, all types of water heating systems (water thermal mass storage, heat-pipe heating system, shallow solar pond heating systems, geothermal based heating systems viz. ground source heat pump system, solar-assisted ground source heat pump system, aquifer coupled heat exchanger system), ground air collector system, north wall and thermal curtain, and soil heat exchanger system. Important aspects of each representative model such as: type, tool/program used for solution/simulation, input data used to run simulations, interactive components, parameters studied, assumption made, important model characteristics and results obtained are discussed at length. Based on the compiled information, a generalized procedure is devised to formulate greenhouse thermal model. Finally, based on the main characteristics and results of the study, some important conclusions are drawn and suggestions made for further studies.
The study reveals the comparison of Nd0.9Pr0.1CrO3 and Nd0.9Eu0.1CrO3 samples where the A-site is doped by Pr3+ having the larger ionic radius (1.126 A°) corresponding to less chemical pressure and ...Eu3+ (1.066 A°) having the smaller ionic radius corresponding to enhanced chemical pressure exerted on the NdCrO3, with the help of X-ray diffraction, Raman spetroscopy, UV-visible spectroscopy, and dc magnetization measurements. The different spin configuration Pr3+ (J = 4) and Eu3+ (J = 0) altering the strong coupling between Nd3+ (J = 9/2) and Cr3+ (S = 3/2) spins result in the variation of the optical band gap, fermi energy and exchange bias.
The direct random phase approximation (dRPA) combined with Kohn–Sham reference orbitals is among the most promising tools in computational chemistry and applicable in many areas of chemistry and ...physics. The reason for this is that it scales as N 4 with the system size, which is a considerable advantage over the accurate ab initio wave function methods like standard coupled-cluster. dRPA also yields a considerably more accurate description of thermodynamic and electronic properties than standard density-functional theory methods. It is also able to describe strong static electron correlation effects even in large systems with a small or vanishing band gap missed by common single-reference methods. However, dRPA has several flaws due to its self-correlation error. In order to obtain accurate and precise reaction energies, barriers and noncovalent intra- and intermolecular interactions, we construct a new dual-hybrid dRPA (hybridization of exact and semilocal exchange in both the energy and the orbitals) and test the performance of this new functional on isogyric, isodesmic, hypohomodesmotic, homodesmotic, and hyperhomodesmotic reaction classes. We also use a test set of 14 Diels–Alder reactions, six atomization energies (AE6), 38 hydrocarbon atomization energies, and 100 reaction barrier heights (DBH24, HT-BH38, and NHT-BH38). For noncovalent complexes, we use the NCCE31 and S22 test sets. To test the intramolecular interactions, we use a set of alkane, cysteine, phenylalanine-glycine-glycine tripeptide, and monosaccharide conformers. We also discuss the delocalization and static correlation errors. We show that a universally accurate description of chemical properties can be provided by a large, 75% exact exchange mixing both in the calculation of the reference orbitals and the final energy.
Herein, the biopolymer chitosan has been modified via click chemistry using the robust copper catalyzed azide-alkyne cycloaddition (CuAAC) reaction. CuAAC reaction on chitosan skeleton is an ...interesting way for its modification and chitosan is prone to be modified at C-2, C-3 and C-6 positions where free amino and hydroxyl groups are present. Initially,
N
-azidated chitosan was prepared and then CuAAC click reaction was carried out to synthesize chitosan-1,2,3-triazole derivative (CS-triazole derivative) by a novel facile method starting from CaC
2
. The synthesized polymer derivative has been well characterized by FT-IR,
1
H NMR and
13
C NMR spectroscopic analyses. FT-IR spectra of
N
-azidated chitosan shows a peak at 2115 cm
−1
which confirms the presence of azide functionality whereas the peak at 1560 cm
−1
confirms the presence of unsaturation in the triazole moiety of final product. Proton NMR signal at 8.28 ppm and carbon NMR signal at 130 ppm and 144 ppm confirm the presence of = C-H protons and unsaturation in the triazole ring respectively for the synthesized derivative. On biological evaluation, CS-triazole derivative showed antibacterial activity against gram-negative (
E. coli
) and gram-positive (
B. subtilis
) bacteria (using the agar diffusion method). The antibacterial results were interpreted in terms of zone of inhibition (ZOI) which depicted that chitosan triazole derivative showed better ZOI than pristine chitosan and
N
-azidated chitosan. Also, ZOI for gram-negative bacteria was better than that of gram-positive bacteria. Moreover, synthesized chitosan triazole derivative also exhibited significant antioxidant property (tested using DPPH assay method).
Recently, we have constructed a dual-hybrid direct random phase approximation method, called dRPA75, and demonstrated its good performance on reaction energies, barrier heights, and noncovalent ...interactions of main-group elements. However, this method has also shown significant but quite systematic errors in the computed atomization energies. In this paper, we suggest a constrained spin-component scaling formalism for the dRPA75 method (SCS-dRPA75) in order to overcome the large error in the computed atomization energies, preserving the good performance of this method on spin-unpolarized systems at the same time. The SCS-dRPA75 method with the aug-cc-pVTZ basis set results in an average error lower than 1.5 kcal mol–1 for the entire n-homodesmotic hierarchy of hydrocarbon reactions (RC0–RC5 test sets). The overall performance of this method is better than the related direct random phase approximation-based double-hybrid PWRB95 method on open-shell systems of main-group elements (from the GMTKN30 database) and comparable to the best O(N 4)-scaling opposite-spin second-order perturbation theory-based double-hybrid methods like PWPB95-D3 and to the O(N 5)-scaling RPAX2@PBEx method, which also includes exchange interactions. Furthermore, it gives well-balanced performance on many types of barrier heights similarly to the best O(N 5)-scaling second-order perturbation theory-based or spin-component scaled second-order perturbation theory-based double-hybrid methods such as XYG3 or DSD-PBEhB95. Finally, we show that the SCS-dRPA75 method has reduced self-interaction and delocalization errors compared to the parent dRPA75 method and a slightly smaller static correlation error than the related PWRB95 method.
We showed that the ferromagnetic correlation extended far into what was thought to be the paramagnetic phase for pristine Ca3Co2O6 in our Bi-substituted compound and found a correlation between ...magnetic and dielectric anomaly in this region. We have observed enhancement of dielectric property (dielectric constant 200 with a loss factor 0.01 at 1 MHz), which is attributed to the high ionic polarizability of Bi. The dielectric response curve indicates two stages in the relaxation process, which is confirmed by the two peaks in the loss tangent (tanδ) plot. Higher relaxation time (8.9 × 10−10 s) obtained from analyzing the dielectric response curve using Arrhenius law suggested a collective dielectric relaxation process in this system.
Little is known about biological significance of effects of dietary Boron (B) and Calcium (Ca) interaction on health and production of farm animals. This is a preliminary investigation to evaluate ...the effects of B supplementation in lambs fed diets with (normal) or without adequate (low) levels of Ca. Twenty-four crossbred ram lambs were randomly distributed into four groups with six animals each in a 2x2 factorial design namely, normal-Ca diet (NCa) and low-Ca diet (LCa) fed without or with 40 ppm B (NCaB-40 and LCaB-40). The lambs were fed paddy straw and hybrid napier hay-based total mixed ration (60 roughage: 40 concentrate) during 180 days experimental period. Compared to control, the LCa diet lowered (P<0.01) average daily gain of lambs, but B-supplementation (LCaB-40) of the same nullified the effect. The lowered (P<0.05) total antioxidant activity and humoral immune response in lambs fed LCa diet were restored (P>0.05) to become at par with the control (NCa) upon supplementation of B (LCaB-40). The mRNA expression of SOD1 was lowered (P<0.05) due to LCa diet feeding which too was normalized on B-supplementation to become at par (P>0.05) with the control (NCa). Further, B-supplementation restored lowered (P<0.05) SOD1 gene expression on LCa diet, but enhanced (P<0.05) that in NCaB-40 group, when compared to the control (NCa) diet fed animals. However, these variations were not reflected in the SOD activity in the erythrocytes. The cell-mediated immune response was higher (P<0.05) in lambs fed LCa and LCaB-40 groups and there was no significant interaction between the levels of either Ca or B in diets with the period of immune response measurement. B- supplementation of LCa diet ameliorated tissue degenerative changes in liver and kidney. It was concluded that feeding LCa diet to lambs resulted in reduced growth rate, total antioxidant activity, humoral immune response along with degenerative changes in liver and kidney tissues, but B-supplementation of such diet restored most of these changes and ameliorated histopathological alterations.
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