Molecular recognition of La@C82 endohedral metallofullerene by an isophthaloyl-bridged porphyrin dimer

La@C₈₂ is recognized by an isophthaloyl-bridged porphyrin dimer forming a stable 1:1 supramolecular complex with an association constant K_assoc = (67.3 ± 3.2) × 10³ M⁻¹.     

“I Actually Learned A Lot from This”: A Field Assignment to Prepare Future Preservice Math Teachers for Culturally Diverse Classrooms

Teacher education programs are cognizant of the need to prepare preservice teachers (PTs) to work effectively with children from diverse cultural backgrounds. Well-constructedfield experiences can help PTs develop awareness and gain understanding of important cultural considerations related to effective teaching and learning ( Sleeter, 2001 ). This paper describes a unique field assignment created for an Elementary Math Methods course in which 61 PTs were trained to conduct a semi-structured interview with a student whose cultural background was different than their own. PTs transcribed their own interviews and completed a guided reflection on their experiences. Reflections were submitted and analyzed for emerging themes. Analyses suggest that the structured interview component of this field assignment provided PTs with increased insight into mathematics instruction and the learning needs of diverse students. We also discuss the value and limitations of this instructional innovation and propose avenues by which to continue to help PTs grow toward becoming culturally relevant pedagogists ( Irvine, 2003 ).     

Losartan Interactions with 2-Hydroxypropyl-β-CD

Losartan potassium salt (LSR) is a well-known antihypertensive drug with proven beneficial effects on human health. Its formulation with the non-toxic 2-hydroxypropyl-β-cyclodextrin (2-HP-β-CD) could improve its pharmacological profile. Thus, its molecular interactions are studied using a combination of Differential Scanning Calorimetry (DSC), Nuclear Magnetic Resonance (NMR) and Molecular Dynamics (MD). First, its complexation is shown through Differential Scanning Calorimetry as lyophilization provided distinct thermal properties in comparison to the mixture. The complexation is further proved by utilizing the chemical shift changes in the complexation and T1 values. Furthermore, the reversible favorable complexation was shown by MD calculations. Such physical chemical properties provide evidence that this formulation must be further explored through biological experiments.     

A Platform Approach to Cleavable Macrocycles for the Controlled Disassembly of Mechanically Caged Molecules

Inspired by interlocked oligonucleotides, peptides and knotted proteins, synthetic systems where a macrocycle cages a bioactive species that is “switched on” by breaking the mechanical bond have been reported. However, to date, each example uses a bespoke chemical design. Here we present a platform approach to mechanically caged structures wherein a single macrocycle precursor is diversified at a late stage to include a range of trigger units that control ring opening in response to enzymatic, chemical, or photochemical stimuli. We also demonstrate that our approach is applicable to other classes of macrocycles suitable for rotaxane and catenane formation.     

cis‐Dichloro(dimethyl sulfoxide‐S)(2‐methoxypyridine‐N)platinum(II)

The title complex, [PtCl₂(C₆H₇NO)(C₂H₆OS)], exhibits square‐planar geometry. The plane of the pyridine ring makes a dihedral angle of 67.2 (3)° with the square plane of the metal center. The S—O bond is nearly aligned with the adjacent Pt—N bond, leaving the methyl groups of the di­methyl sulfoxide ligand to stagger the Pt—Cl bond.     

On-line sorptive preconcentration platform incorporating a readily exchangeable Oasis HLB extraction micro-cartridge for trace cadmium and lead determination by flow injection-flame atomic absorption spectrometry

A simple, sensitive and inexpensive flow injection solid phase extraction (SPE) system was developed for automatic determination of trace level concentrations of metals. The potentials of this novel scheme, coupled to flame atomic absorption spectrometry (FAAS), were demonstrated for trace cadmium and lead determination in environmental water samples. The method was based on on-line chelate complex formation of target species with ammonium diethyldithiophosphate (DDTP), retention onto the surface of reversed-phase poly(divinylbenzene-N-vinylpyrrolidone) co-polymeric beads (Oasis HLB) and elution with methanol prior to atomization. A special PVC adapter was designed for easy and rapid replacement of the commercially available SPE cartridge. All main chemical and hydrodynamic parameters affecting the complex formation, sorption and elution of the analyte were optimized thoroughly. Moreover, the effect of potential interfering species occurring in environmental samples was also explored.For 90 s preconcentration time, enhancement factors of 155 and 180, detection limits (3s) of 0.09 μg L^− 1 and 0.9 μg L^− 1 and relative standard deviations (R.S.D.) of 2.9% (at 4.0 μg L^− 1) and 2.6% (at 20.0 μg L^− 1) were obtained for cadmium and lead, respectively, with a sample throughput of 24 h^− 1. The measurement trueness of the developed method was evaluated by analyzing a certified reference material and spiked environmental water samples. The proposed method is well suited to detect the target elements at concentration levels below the maximum allowed concentrations endorsed by the European Framework Directive (2008/105/EC) in inland and coastal waters.     

Mixed magnesium and nickel nitrate hexahydrates: an unexpected restructuring

Single crystals of the congruently melting equimolar mixture of magnesium nitrate hexahydrate and nickel nitrate hexahydrate have been grown. The compound crystallizes in a structure foreign to both components, namely in the monoclinic cobalt nitrate hexahydrate structure. The cations are located at random on the cation sub-lattice of the latter crystalline structure.     

Solid–liquid phase equilibria in the systems K2SO4–MSO4–H2O (M = Co,Ni, Cu) from ambient to enhanced temperatures

Reviewing the literature solubility isotherms in the ternary systems K₂SO₄–MSO₄–H₂O (M = Co, Ni, Cu, Zn) revealed a lack at ambient temperatures. The solid–liquid phase equilibria have been determined in the systems K₂SO₄–MSO₄–H₂O (M = Co, Ni, Cu) at T = 313 K. With increasing bivalent metal sulfate concentration, the solubility of potassium sulfate rises until the two-salt point is reached. Reciprocally, the solubility of the bivalent metal sulfate hydrates (CoSO₄·7H₂O, α-NiSO₄·6H₂O, CuSO₄·5H₂O) increases with rising potassium sulfate concentration. In all three systems the double salts of Tutton's type K₂SO₄·MSO₄·6H₂O (M = Co, Ni, Cu) are formed.     

Profit loss in differentiated oligopolies

We provide sharp lower and upper bounds on the ratio of decentralized to centralized profits when multiproduct firms offering differentiated products engage in price competition. The bounds depend on the demand sensitivity matrix but are independent of marginal costs.     

Dynamic pricing and inventory control: robust vs. stochastic uncertainty models—a computational study

In this paper, we consider a variety of models for dealing with demand uncertainty for a joint dynamic pricing and inventory control problem in a make-to-stock manufacturing system. We consider a multi-product capacitated, dynamic setting, where demand depends linearly on the price. Our goal is to address demand uncertainty using various robust and stochastic optimization approaches. For each of these approaches, we first introduce closed-loop formulations (adjustable robust and dynamic programming), where decisions for a given time period are made at the beginning of the time period, and uncertainty unfolds as time evolves. We then describe models in an open-loop setting, where decisions for the entire time horizon must be made at time zero. We conclude that the affine adjustable robust approach performs well (when compared to the other approaches such as dynamic programming, stochastic programming and robust open loop approaches) in terms of realized profits and protection against constraint violation while at the same time it is computationally tractable. Furthermore, we compare the complexity of these models and discuss some insights on a numerical example.