Microwave spectrum of PHD: hyperfine structure

The rotational spectrum of the monodeuterated PH₂ radical was studied using a source-modulated submillimeter-wave spectrometer. The PHD radical was generated in a free space absorption cell by a dc-glow discharge in a gas mixture of PH₃ and D₂. Six a-type and 20 b-type rotational transitions were observed in the frequency region of 170-670 GHz. Hyperfine structure due to the deuterium nucleus was resolved only in the rotational transitions of 1₁₁-0₀₀ and 1₁₀-1₀₁ and in the low F₂ components of N=2-1 transitions. A total of 219 spectral lines were measured of which 145 were analyzed by least-squares methods. These yielded 34 precise molecular constants including the hyperfine coupling constants of phosphorus, hydrogen, and deuterium. The principal axes and principal values of the magnetic dipole coupling tensors of hydrogen in PH₂ and deuterium in PD₂ were derived from the observed values of PHD, PH₂ and PD₂. The principal axis of the hydrogen magnetic dipole coupling tensor in PH₂ makes an angle of 2.29° with the PH bond and its T_σ and T_⊥ principal values are determined to be 12.93 and −18.39 MHz, respectively.     

Low energy SIMS study on multi-built-up layer of cobalt(II) stearate

The surface of multi-built-up layer of cobalt(II) stearate on copper substrate has been studied by means of low energy SIMS. The sampling surfaces were impacted with 700 eV, 8 × 10^?7 Å/cm², Ar⁺ ions. In each group (odd-numbered accumulated and even-numbered accumulated samples), the ⁵⁸Co⁺ intensities at the initial bombardment responded to the number of the accumulation, respectively. The ⁵⁸Co⁺ ion intensities from even-numbered accumulated samples were observed more than the expected values from a proportionality between the accumulation number and ⁵⁸Co⁺ intensities.     

Fourier transform infrared spectroscopic study of water-in-supercritical CO2 microemulsion as a function of water content

Fourier transform infrared (FT-IR) spectrum of water-in-supercritical CO(2) microemulsion was measured at 60 degrees C and 30.0 MPa over a wide range of water/CO(2) ratio from 0.0 to 1.2 wt % to study the distribution of water into CO(2), interfacial area around surfactant headgroup, and core water pool. The microemulsion was stabilized by sodium bis(1H,1H,2H, 2H-heptadecafluorodecyl)-2-sulfosuccinate [8FS(EO)(2)] equimolarly mixed with sodium 1-oxo-1-[4-(tridecafluorohexyl)phenyl]-2-hexanesulfonate [FC6HC4] or with poly(ethylene glycol) 2,6,8-trimethyl-4-nonyl ether [TMN-6]. The signal area of the O-H stretching band of water suggested that the number of water molecules in the microemulsion increases linearly with the water/CO(2) ratio, except for a slow initial increase below 0.4 wt % due to a part of water dissolved in CO(2). The amount of water in CO(2) was evaluated by decomposing the bending band of water into two components, one at lower frequency ascribed to water in CO(2) and the other at higher frequency to water in the microemulsion. The decomposition confirmed that CO(2) is saturated with water at the water content of 0.4 wt %. It was also revealed, from the symmetric SO stretching frequency of the surfactant, that the sulfonate headgroup is completely hydrated at the water/CO(2) ratio of 0.4-0.5 wt %. The results demonstrated that water is introduced preferentially into CO(2) and the interfacial area at small water content, and then is loaded into the micelle core after the saturation of CO(2) with water and the full hydration of the surfactant headgroup.     

Dominating Cycles and Forbidden Pairs Containing $$P_{5}$$

A cycle C in a graph G is dominating if every edge of G is incident with at least one vertex of C. For a set \(\mathcal {H}\) of connected graphs, a graph G is said to be \(\mathcal {H}\)-free if G does not contain any member of \(\mathcal {H}\) as an induced subgraph. When \(|\mathcal {H}| = 2, \mathcal {H}\) is called a forbidden pair. In this paper, we investigate the characterization of the class of the forbidden pairs guaranteeing the existence of a dominating cycle and show the following two results: (i) Every 2-connected \(\{P_{5}, K_{4}^{-}\}\)-free graph contains a longest cycle which is a dominating cycle. (ii) Every 2-connected \(\{P_{5}, W^{*}\}\)-free graph contains a longest cycle which is a dominating cycle. Here \(P_{5}\) is the path of order \(5, K_{4}^{-}\) is the graph obtained from the complete graph of order 4 by removing one edge, and \(W^{*}\) is the graph obtained from two triangles and an edge by identifying one vertex in each.     

Efficient Generation of Microdroplets Using Tail Breakup Induced with Multi-Branch Channels

In recent years, research on the application of microdroplets in the fields of biotechnology and chemistry has made remarkable progress, but the technology for the stable generation of single-micrometer-scale microdroplets has not yet been established. In this paper, we developed an efficient and stable single-micrometer-scale droplet generation device based on the fragmentation of droplet tails, called “tail thread mode”, that appears under moderate flow conditions. This method can efficiently encapsulate microbeads that mimic cells and chemical products in passively generated single-micrometer-scale microdroplets. The device has a simple 2D structure; a T-junction is used for droplet generation; and in the downstream, multi-branch channels are designed for droplet deformation into the tail. Several 1–2 µm droplets were successfully produced by the tail’s fragmentation; this continuous splitting was induced by the branch channels. We examined a wide range of experimental conditions and found the optimal flow rate condition can be reduced to one-tenth compared to the conventional tip-streaming method. A mold was fabricated by simple soft lithography, and a polydimethylsiloxane (PDMS) device was fabricated using the mold. Based on the 15 patterns of experimental conditions and the results, the key factors for the generation of microdroplets in this device were examined. In the most efficient condition, 61.1% of the total droplets generated were smaller than 2 μm.     

Suffruyabiosides A and B, two new monoterpene diglycosides from moutan cortex

Two new monoterpene diglycosides, suffruyabiosides A and B, and seven known compounds 3-9 were isolated from Moutan Cortex (root cortex of Paeonia suffruticosa Andrews). The structures were elucidated on the basis of 2D NMR spectral data. Suffruyabiosides A and B are rare monoterpene diglycosides, including a cellobiose in the molecules. Salicylpaeoniflorin (4) had a antiproliferation effect similar to paeoniflorin (3) on human lung adenocarcinoma epitherial A549 cells. Galloylpaeoniflorin (8) and salicylpaeoniflorin (4) revealed a more pronounced radical scavenging effect than a-tocopherol (positive control). An increase in the number of phenolic hydroxyl groups produced a more effective radical scavenging effect [8 > mudanpioside E (6) > oxypaeoniflorin (5)]. Comparison of the effects of 4 and 5 showed that o-substitution with a phenolic hydroxyl group was more effective than p-substitution. The results suggest that salicylpaeoniflorin (4) may be useful as a cytotoxic and a radical scavenging agent.     

The first total synthesis and reassignment of the relative stereochemistry of 16-hydroxy-16,22-dihydroapparicine

We report the first total synthesis and reassignment of the relative stereochemistry of naturally occurring 16-hydroxy-16,22-dihydroapparicine. Our novel route proceeds by a cascade reaction to efficiently construct a 1-azabicyclo[4.2.2]decane core, along with two stereocenters (C-15 and C-16). The C-16 quaternary carbon was constructed through stereospecific 1,2-addition using an indole nucleophile to an aldehyde or a methylketone. The stereospecific synthesis of two diastereomers of the target product has revealed the true relative stereochemistry of the natural compound.     

Upper Bounds on the Paired Domination Subdivision Number of a Graph

A paired dominating set of a graph G with no isolated vertex is a dominating set S of vertices such that the subgraph induced by S in G has a perfect matching. The paired domination number of G, denoted by γ _pr(G), is the minimum cardinality of a paired dominating set of G. The paired domination subdivision number ${{\rm sd}_{\gamma _{\rm pr}}(G)}$ is the minimum number of edges to be subdivided (each edge of G can be subdivided at most once) in order to increase the paired domination number. In this paper, we show that if G is a connected graph of order at least 4, then ${{\rm sd}_{\gamma _{\rm pr}}(G)\leq 2|V(G)|-5}$ . We also characterize trees T such that ${{\rm sd}_{\gamma _{\rm pr}}(T) \geq |V(T)| /2}$ .