Optimization of heat transfer and pressure drop in a tube with loose-fit perforated twisted tapes by Taguchi method and grey relational analysis

Journal of Thermal Analysis and Calorimetry - This work introduces the determination of the optimum values of the design parameters in a tube with loose-fit perforated twisted tapes. The effects of...     

Biological assays and theoretical density functional theory calculations of Rh(I), Ir(III), and Ru(II) complexes of chiral phosphinite ligand

Four metal complexes, IL-OPPh₂-Ru-p-cymene (3) , IL-OPPh₂-Ru-benzene (4) , IL-OPPh₂-Ir-Cp* (5) , IL-OPPh₂-Rh-COD (6) , have been evaluated for in vitro antioxidant activity such as 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and reducing power activity. Maximum scavenging activity (71.43%) was obtained with IL-OPPh₂-Ru-p-cymene, whereas IL-OPPh₂-Rh-COD showed the highest reducing power ability. The complexes were also studied for their antimicrobial activity against three Gram-positive and three Gram-negative bacteria. In addition, DNA binding of the complexes was evaluated using calf thymus DNA. Both Ru(II) complexes exhibited good DNA-binding activity while the other complexes did not have any activity. Furthermore, ab initio quantum calculations of four complexes were also carried out using density functional theory to better understand their chemical behaviors.     

[Hg2(μ‐bpe)(μ‐OAc)2(μ‐SCN)2]n,a New Two‐Dimensional Coordination Polymer Involving Three Simultaneously Bridging Ligands: 1,2‐Bis(4‐pyridyle)ethene,Acetate, and Thiocyanate

A new mercury(II) complex of 1,2‐bis(4‐pyridyle)ethene (bpe) with anionic acetate and thiocyanate ligands has been synthesized and characterized by elemental analysis, IR, ¹H NMR and ¹³C NMR spectroscopy. The single crystal X‐ray analysis shows that the complex is a two‐dimensional polymer with simultaneously bridging 1,2‐bis(4‐pyridyle)ethane, acetate and thiocyanate ligands and basic repeating dimeric [Hg₂(μ‐bpe)(μ‐OAc)₂(μ‐SCN)₂] units. The two‐dimensional system forms a three‐dimensional network by packing via π‐π stacking interactions.     

Two-dimensional supramolecular networks generated from weak AgCpy interactions: Synthesis, structural, thermal and fluorescence studies of silver(I) complexes of 5,5-diethylbarbiturato with pyridine-2-ylmethanol and 2,6-dimethoxypyridine

Two new silver(I) complexes [Ag(barb)(pym)]·H₂O (1) and [Ag(barb)(dmpy)]·1.5H₂O (2) (barb = 5,5-diethylbarbiturate, pym = pyridine-2-ylmethanol and dmpy = 2,6-dimethoxypyridine) have been synthesized and characterized by elemental analysis, IR spectroscopy and single crystal X-ray diffraction. In both complexes, the silver(I) ions are linearly coordinated by the N atoms of a barb anion and a pym or a dmpy ligand, forming mononuclear species. The molecules of 1 and 2 are doubly bridged by N–HO hydrogen bonds involving the barb moieties and these hydrogen-bonded dimers are assembled into two-dimensional layered networks through weak AgC_py (η¹) interactions of ca. 3.3 Å. Additionally, the thermal and fluorescent properties of these complexes are also investigated.     

Detection of Variation in Long-Term Micropropagated Mature Pistachio via DNA-Based Molecular Markers

Determination of genetic stability of in vitro-grown plantlets is needed for safe and large-scale production of mature trees. In this study, genetic variation of long-term micropropagated mature pistachio developed through direct shoot bud regeneration using apical buds (protocol A) and in vitro-derived leaves (protocol B) was assessed via DNA-based molecular markers. Randomly amplified polymorphic DNA (RAPD), inter-simple sequence repeat (ISSR), and amplified fragment length polymorphism (AFLP) were employed, and the obtained PIC values from RAPD (0.226), ISSR (0.220), and AFLP (0.241) showed that micropropagation of pistachio for different periods of time resulted in “reasonable polymorphism” among donor plant and its 18 clones. Mantel’s test showed a consistence polymorphism level between marker systems based on similarity matrices. In conclusion, this is the first study on occurrence of genetic variability in long-term micropropagated mature pistachio plantlets. The obtained results clearly indicated that different marker approaches used in this study are reliable for assessing tissue culture-induced variations in long-term cultured pistachio plantlets.     

Oxidation of Aryl Alkyl Ketones To α-Acyloxy, α-(Camphorsulfonyloxy), or α-Hydroxy Derivatives Using Manganese(III) Acetate in Combination with Carboxylic Acids or (1S)-(+)-10-Camphorsulfonic Acid

The α-oxidation of aryl alkyl ketones using manganese(III) acetate in the presence of various carboxylic acids and (1S)-(+)-10-camphorsulfonic acid provided a convenient synthesis of α-acyloxy, α-(10-camphorsulfonyloxy), and α-hydroxy derivatives in good yield.     

Bis(2‐pyridyl­methanol)­bis­(saccharinato)­zinc(II) and ‐cadmium(II) at 120 K: three‐dimensional structures containing both N‐and O‐coordinated ambi­dentate saccharinate ligands

The title complexes [M(sac)₂(mpy)₂] [sac is saccharinate (C₇H₄NO₃S) and mpy is 2‐pyridyl­methanol (C₆H₇NO)], with M = Zn^II and Cd^II, are isostructural and consist of neutral mol­ecules. The Zn^II or Cd^II cations are octahedrally coordinated by the two neutral mpy and two anionic sac ligands. The mpy ligand acts as a bidentate donor through the amine N and hydroxyl O atoms. The sac ligands exhibit an ambidentate coordination behaviour; one is N‐coordinated and the other is O‐coordinated within the same coordination octahedron. The crystal packing is determined by C—H?O‐type hydrogen bonding, as well as by weak py–py and sac–sac aromatic π–π‐stacking interactions.     

A numerical algorithm for the solution of nonlinear fractional differential equations via beta‐derivatives

In this paper, the sinc‐collocation method (SCM) is investigated to obtain the solution of the nonlinear fractional order differential equations based on the relatively new defined fractional derivative, beta‐derivative. For this purpose, a theorem is proved for the approximate solution obtained from the SCM. Moreover, convergence analysis of the SCM is presented. To show the efficiency and the simplicity of the proposed method, some examples are solved, and the results are compared with the exact solutions of the considered equations.     

trans‐Bis­(diethano­lamine)­bis­(iso­thio­cyanato)­nickel(II)

In the neutral title complex, trans‐bis(2,2′‐imino­di­ethanol‐N,O)­bis­(iso­thio­cyanato)­nickel(II), [Ni(NCS)₂(C₄H₁₁NO₂)₂], the iso­thio­cyanate ions and the di­ethanol­amine mol­ecules act as mono­dentate and bi­dentate ligands, respectively. The Ni^II ion exhibits a distorted octahedral configuration with crystallographically imposed inversion symmetry and N_NCS—Ni—N_amine and N_NCS—Ni—O_amine bond angles of 88.78 (10) and 89.44 (10)°, respectively. The Ni—N bond distances are in the range 2.069 (3)–2.096 (2) Å. The mol­ecules are linked by hydrogen bonds to form a three‐dimensional infinite lattice.     

Pediatric abdominal masses: diagnostic accuracy of diffusion weighted MRI

Purpose

To retrospectively identify apparent diffusion coefficient (ADC) values of pediatric abdominal mass lesions, to determine whether measured ADC of the lesions and signal intensity on diffusion-weighted (DW) images allow discrimination between benign and malignant mass lesions.

Materials and Methods

Approval for this retrospective study was obtained from the institutional review board. Children with abdominal mass lesions, who were examined by DW magnetic resonance imaging (MRI) were included in this study. DW MR images were obtained in the axial plane by using a non breath-hold single-shot spin-echo sequence on a 1.5-T MR scanner. ADCs were calculated for each lesion. ADC values were compared with Mann–Whitney U test. Receiver operating characteristic curve analysis was performed to determine cut-off values for ADC. The results of visual assessment on b800 images and ADC map images were compared with chi-square test.

Results

Thirty-one abdominal mass lesions (16 benign, 15 malignant) in 26 patients (15 girls, 11 boys, ranging from 2 days to 17 years with 6.9 years mean) underwent MRI. Benign lesions had significantly higher ADC values than malignant ones (P<.001). The mean ADCs of malignant lesions were 0.84±1.7×10⁻³ mm²/s, while the mean ADCs of the benign ones were 2.28±1.00×10⁻³ mm²/s. With respect to cutoff values of ADC: 1.11×10⁻³ mm²/s, sensitivity and negative predictive values were 100%, specificity was 78.6% and positive predictive value was 83.3%. For b800 and ADC map images, there were statistically significant differences on visual assessment. All malignant lesions had variable degrees of high signal intensity whereas eight of the 16 benign ones had low signal intensities on b800 images (P<.001). On ADC map images, all malignant lesions were hypointense and most of the benign ones (n=11, 68.7%) were hyperintense (P<.001).

Conclusion

DW imaging can be used for reliable discrimination of benign and malignant pediatric abdominal mass lesions based on considerable differences in the ADC values and signal intensity changes.