Reduction by monovalent zinc, cadmium, and nickel cations

Understanding of chemical properties of monovalent transition metal cations in aqueous solutions was obtained by a study of kinetics of reduction of different inorganic substrates by zinc, cadmium, and nickel

New Perspective in the Formulation and Characterization of Didodecyldimethylammonium Bromide (DMAB) Stabilized Poly(Lactic-co-Glycolic Acid) (PLGA) Nanoparticles

Over the last few decades the establishment of nanoparticles as suitable drug carriers with the transport of drugs across biological barriers such as the gastrointestinal barrier moved into the focus of many research groups. Besides drug transport such carrier systems are well suited for the protection of drugs against enzymatic and chemical degradation. The preparation of biocompatible and biodegradable nanoparticles based on poly(lactic-co-glycolic acid) (PLGA) is intensively described in literature, while especially nanoparticles with cationic properties show a promising increased cellular uptake. This is due to the electrostatic interaction between the cationic surface and the negatively charged lipid membrane of the cells. Even though several studies achieved the successful preparation of nanoparticles stabilized with the cationic surfactants such as didodecyldimethylammonium bromide (DMAB), in most cases insufficient attention was paid to a precise analytical characterization of the nanoparticle system. The aim of the present work was to overcome this deficit by presenting a new perspective in the formulation and characterization of DMAB-stabilized PLGA nanoparticles. Therefore these nanoparticles were carefully examined with regard to particle diameter, zeta potential, the effect of variation in stabilizer concentration, residual DMAB content, and electrolyte stability. Without any steric stabilization, the DMAB-modified nanoparticles were sensitive to typical electrolyte concentrations of biological environments due to compression of the electrical double layer in conjunction with a decrease in zeta potential. To handle this problem, the present study proposed two modifications to enable electrolyte stability. Both polyvinyl alcohol (PVA) and polyethylene glycol (PEG) modified DMAB-PLGA-nanoparticles were stable during electrolyte addition. Furthermore, in contrast to unmodified DMAB-PLGA-nanoparticles and free DMAB, such modifications led to a lower cytotoxic activity against Caco-2 cells. In conclusion this study offers a closer and critical point of view on preparation, in vitro and analytical evaluation of DMAB-stabilized PLGA nanoparticles for the physiological use

Preparation of Des-alanine-B30-insulin via the Tryptic Hydrolysis of Porcine Insulin Modified at the Arginyl Residue by Cyclohexane-1,2-dione

The feasibility of the selective modification of the argimyl residue in insulin by the method of Patthy and Smith (J. Biol. Chem. 250 (1975) 557-564; ibid. 565-569), involving the reversible reaction of cyclohexane-1,2-dicme wiith the guanidrinio function of arginine in a borate buffer, was studied. It was found that cyclohexane-1,2- -di,one reacts specifically and completely Wli.th the arginyl residue of porcine insulin in 0.2 M borate buffer at pH = 9.0 to form a single addition product ([DHCH-Arg-B22]-insulin complex I) which, upon treatment with 0.5 M hydroxylamine at pH = 7.0, regenerated insulin of unchanged biological activity. Incubation of I with trypsin led to specific cleavage at the Lys-B29 residue to give des- Ala-B30-[DHCH-Arg-B22]-insulin complex II, which, upon hydroxylamine treatment afforded des-Ala-B30-insulin (III) in high yield

The Synthesis of Fully Boe-Protected Insulin Derivatives by Use of Boc-Azide - 1,1,3,3-Tetramethylguanidine - 1,2,4-Triazole as an Effective Acylating System. - A Simple and Sensitive Fluorescence Test for Determining the Degree of N-Substitution

Acylation of desoctapeptide-(1323-3°) -insulin pentamethyl ester (II), insulin arid insulin \u27hexamethyl ester was carried out with Boc-azide in dimethylformamide in the presence of 1,1,3,3-tetramethylguanidine as a base and 1,2,4-triazole as an activator to give very homogeneous di-Boc-desoctapeptide-(B23- 30)-insulin p~ntamethyl ester (III), tri-Boc-insulin (IV) and tri-Boc-insulin hexamethyl ester (V), respectively, in high yield (> 900/o). The degree of substitution of the products was assayed by a simple and sensitive test, based on the fluorescence reaction with primary amines, and expressed as the fluorescence intensity relative to that produced by an equimolar amount of free insulin. A comparison of the fluorescence intensities of III and IV prepared under various conditions indicates that (a) the Boc-azide - 1,1,3,3-tetramethylguanidine - 1,2,4-triazole combination is more effectiv.e than the Boc-azide - imidazole and Boc-azide - triethylamine acylating systems, and (b) the presence of 1,2,4-triazole is·essential for the acylating efficiency of the system employed

Gas generation from Hanford grout samples

In an extension of our work on the radiolytic processes that occur in the waste tanks at the Hanford site, we studied the gas generation from grout samples that contained nuclear waste simulants. Grout is one option for the long-term storage of low-level nuclear waste solutions but the radiolytic effects on grout have not been thoroughly defined. In particular, the generation of potentially flammable and hazardous gases required quantification. A research team at Argonne examined this issue and found that the total amount of gases generated radiolytically from the WHC samples was an order of magnitude higher than predicted. This implies that novel pathways fro charge migration from the solid grout to the associated water are responsible for gas evolution. The grout samples produced hydrogen, nitrous oxide, and carbon monoxide as well as nitrogen and oxygen. Yields of each of these substances were determined for doses that are equivalent to about 80 years storage of the grout. Carbon monoxide, which was produced in 2% yield, is of particular importance because even small amounts may adversely affect catalytic conversion instrumentation that has been planned for installation in the storage vaults

Robotic Lunar Landers for Science and Exploration

NASA Marshall Space Flight Center (MSFC) and The Johns Hopkins University Applied Physics Laboratory (APL) have been conducting mission studies and performing risk reduction activities for NASA s robotic lunar lander flight projects. This paper describes some of the lunar lander concepts derived from these studies conducted by the MSFC/APL Robotic Lunar Lander Development Project team. In addition, the results to date of the lunar lander development risk reduction efforts including high pressure propulsion system testing, structure and mechanism development and testing, long cycle time battery testing and combined GN&C and avionics testing will be addressed. The most visible elements of the risk reduction program are two autonomous lander flight test vehicles: a compressed air system with limited flight durations and a second version using hydrogen peroxide propellant to achieve significantly longer flight times and the ability to more fully exercise flight sensors and algorithms

Expression of PRB, FKBP52 and HB-EGF Relating with Ultrasonic Evaluation of Endometrial Receptivity

Background: To explore the molecular basis of the different ultrasonic patterns of the human endometrium, and the molecular marker basis of local injury. Methodology/Principal Findings: The mRNA and protein expression of FKBP52, progesterone receptor A (PRA), progesterone receptor B (PRB), and HB-EGF were detected in different patterns of the endometrium by real-time RTPCR and immunohistochemistry. There were differences in the mRNA and protein expression of FKBP52, PRB, and HB-EGF in the triple line (Pattern A) and homogeneous (Pattern C) endometrium in the window of implantation. No difference was detected in PRA expression. After local injury, the mRNA expression of HB-EGF significantly increased. In contrast, there was no difference in the mRNA expression of FKBP52, PRB, or PRA. The protein expression of FKBP52, PRB, and HB-EGF increased after local injury. There was no difference in the PRA expression after local injury. Conclusions: PRB, FKBP52, and HB-EGF may be the molecular basis for the classification of the ultrasonic patterns. HB-EGF may be the molecular basis of local injury. Ultrasonic evaluation on the day of ovulation can be effective in predicting the outcome of implantation

NASA's Robotic Lunar Lander Development Program

NASA Marshall Space Flight Center and the Johns Hopkins University Applied Physics Laboratory have developed several mission concepts to place scientific and exploration payloads ranging from 10 kg to more than 200 kg on the surface of the moon. The mission concepts all use a small versatile lander that is capable of precision landing. The results to date of the lunar lander development risk reduction activities including high pressure propulsion system testing, structure and mechanism development and testing, and long cycle time battery testing will be addressed. The most visible elements of the risk reduction program are two fully autonomous lander flight test vehicles. The first utilized a high pressure cold gas system (Cold Gas Test Article) with limited flight durations while the subsequent test vehicle, known as the Warm Gas Test Article, utilizes hydrogen peroxide propellant resulting in significantly longer flight times and the ability to more fully exercise flight sensors and algorithms. The development of the Warm Gas Test Article is a system demonstration and was designed with similarity to an actual lunar lander including energy absorbing landing legs, pulsing thrusters, and flight-like software implementation. A set of outdoor flight tests to demonstrate the initial objectives of the WGTA program was completed in Nov. 2011, and will be discussed