Exploring the Condensation Reaction between Aromatic Nitriles and Amino Thiols To Optimize In Situ Nanoparticle Formation for the Imaging of Proteases and Glycosidases in Cells

The condensation reaction between 6-hydroxy-2-cyanobenzothiazole (CBT) and cysteine has been shown for various applications such as site-specific protein labelling and in vivo cancer imaging. This report further expands the substrate scope of this reaction by varying the substituents on aromatic nitriles and amino thiols and testing their reactivity and ability to form nanoparticles for cell imaging. The structure–activity relationship study leads to the identification of the minimum structural requirement for the macrocyclization and assembly process in forming nanoparticles. One of the scaffolds made of 2-pyrimidinecarbonitrile and cysteine joined by a benzyl linker was applied to design fluorescent probes for imaging caspase-3/7 and β-galactosidase activity in live cells. These results demonstrate the generality of this system for imaging hydrolytic enzymes.     

Electronic state of sulfide-based lithium ion conducting glasses

Electronic states of the sulfide-based lithium ion conducting glasses were calculated by the DV-Xα cluster method. The cluster models were constructed by the coordination number reported by experimental methods and the bond length estimated from the ionic radii of each ion. The movement of the Li ion was simulated by several model clusters with different positions of the moving ion. The relationship between ionic conductivity and the differential total bond overlap population (DBOP) was discussed for the sulfide-based glasses in the systems Li₂S–SiS₂–Al₂S₃ and Li₂S–SiS₂–P₂S₅. In these glasses, the DBOP with the movement of the lithium ion had good negative correlations with the ionic conductivities and positive correlations with the activation energies obtained by the experimental measurements. In any cases, the smaller change of the total bond overlap population of the moving cations played an important role for the fast ion movement in the superionic conducting glasses. This bonding state of the moving cations is one of the characteristics of the electronic state in the sulfide-based lithium ion conducting glasses.     

Electronic state and photosensitivity of metal alkoxides chemically modified with β-diketones

Electronic state and optical absorption spectra of metal alkoxides stabilized with β-diketones (with a variety of substituents) were calculated using first-principle molecular orbital methods. The characteristics of the optical absorption and the mechanism of the photodissociation of alkoxides with irradiation of light are discussed. The position of the first peak observed in the near UV region in the theoretical spectra corresponded to that observed in the experimental spectra with a 25 nm shift toward shorter wavelengths. The first absorption peak observed in the visible range originated from electronic transitions to molecular orbitals, including the antibonding components of the C–O bonding in the chelate ring. The results suggested that the bonding of the chelate rings should be important in controlling the photosensitivity of chemically modified titanium alkoxides.     

Large deviations of Markovian polling models with applications to admission control

In this paper we consider large deviations and admission control problems for a discrete-time Markovian polling system. The system consists of two-parallel queues and multiple heterogeneous servers. The arrival process of each queue is a superposition of mutually independent Markovian on/off processes, and the multiple servers serve independently the two queues according to the so called Bernoulli service schedule. Using the large deviations techniques, we derive upper and lower bounds of the overflow probabilities, and then we present an admission control criterion by which different Quality of Service (QoS) requirements for the two queues are guaranteed.     

Analysis of a system with minimal repair and its application to replacement policy

The periodic replacement with minimal repair at failures is studied by many authors, however, there is not a clear definition for minimal repair. This paper defines a minimal repair in the term of the failure rate and devices some probability quantities and reliability properties. As an application of these results, the replacement model where a system is replaced at time T or at nth failure are considered and the optimum policies are discussed.     

A queueing model of a production system with two machines,one operator and priorities

This paper studies a priority queueing model of a production system in which one operator serves two types of units with overlapping service times. The two types of units arrive in independent Poisson processes. There are two machines in the system. Units of type 1 receive two consecutive types of services at machine #1: the handwork performed by the operator and the automatic machining without the operator. Units of type 2 receive only the handwork performed by the operator at machine #2. The operator attends the two machines according to a strict-priority discipline which always gives units of type 2 higher priority than units of type 1. At each machine the handwork times have a general distribution, and at machine #1 the machining times have an exponential distribution. The Laplace-Stieltjes transform of the queue-size distributions and the waiting time distributions for a stationary process are obtained.     

Chemical bonding and lithium ion conductions in Li3N

Electronic states of Li ions during the ionic jumps in the Li₃N crystal was discussed on the basis of the first principle molecular orbital calculations. The movements of the Li ions were simulated by several model clusters with different positions of the moving cation. The net charge of the moving Li ion and the total bond overlap population between the moving Li ion and the other ions were used for discussion of chemical bonding of the moving Li ion. Furthermore we have estimated the local cluster energy (LCE) to compare the energy change in the different moving path of the Li ion. The total bond overlap population of the moving Li ion along the conduction path changed smaller than those of the other paths. On the other hand, the changes of the net charges of the moving Li ions were similar in any paths. The change of the LCE in the model cluster of the conduction path was much smaller than that in another model cluster. As the results, the smaller change of the total bond overlap population of the moving Li ions played an important role for the fast ion movement in the Li ion conductors, rather than the change of the net charge of the moving Li ions. This bonding state of the moving Li ions is one of the characteristics of the electronic state in Li ion conductors.     

Exploring the Condensation Reaction between Aromatic Nitriles and Amino Thiols To Optimize In Situ Nanoparticle Formation for the Imaging of Proteases and Glycosidases in Cells

The condensation reaction between 6‐hydroxy‐2‐cyanobenzothiazole (CBT) and cysteine has been shown for various applications such as site‐specific protein labelling and in vivo cancer imaging. This report further expands the substrate scope of this reaction by varying the substituents on aromatic nitriles and amino thiols and testing their reactivity and ability to form nanoparticles for cell imaging. The structure–activity relationship study leads to the identification of the minimum structural requirement for the macrocyclization and assembly process in forming nanoparticles. One of the scaffolds made of 2‐pyrimidinecarbonitrile and cysteine joined by a benzyl linker was applied to design fluorescent probes for imaging caspase‐3/7 and β‐galactosidase activity in live cells. These results demonstrate the generality of this system for imaging hydrolytic enzymes.     

Raman spectra of rapidly quenched glasses and melts containing large amounts of Li2O

Raman spectra were measured of rapidly quenched glasses and the corresponding liquids in binary and ternary (pseudobinary) systems composed of Li₂O and several glass-forming oxides such as B₂O₃, P₂O₅, and/or SiO₂. The fractions of the various structural units present were determined from the deconvoluted Raman peaks. Glasses with large amounts of Li₂O were composed of discrete structural units such as ortho-oxoanions and pyro-oxoanions. Based on these data the structural units in the glasses and the corresponding liquids were identical, although in some cases those in the corresponding crystals were different. In the pseudobinary systems combining pyro-oxosalts of lithium borate, phosphate and silicate, non-bridging oxygens were preferentially formed at the phosphate structural units rather than at the borate or silicate structural units. This order of preference was consistent with that of the acidity of the glass-forming oxides in the liquids.     

Application of the DV-Xα cluster method to calculations of the electronic structure of silicate and phosphate glasses

The electronic structure of simple silicate and phosphate clusters, which are assumed to exist in rapidly quenched Li₂O---SiO₂ and Li₂O---P₂O₅ glasses, has been calculated by the discrete variational (DV)-Xα molecular orbital method. The calculations have been carried out for several sizes of clusters, namely, tetrahedral units (SiO₄⁴⁻ and PO₄³⁻), dimers (Si₂O₇⁶⁻ and P₂O₇⁴⁻), and trimers (Si₃O₉⁶⁻ and P₃O₉³⁻). For both systems the valence electronic state is characterized by an occupied valence band, with O 2p components, and an unoccupied band of Si or P orbitals, separated by an energy gap. The energy gap between the highest occupied molecular orbital (HOMO) and the loest unoccupied molecular orbital (LUMO) decreases with increasing cluster size. A mulliken population analysis show that the negative effective charge on the non-bridging oxygens is decreased with decreasing energy gap. The bond order of the Si---O and P---O bonds, and thus the strength of these bonds, is increased with increasing cluster size.