In vitro evaluation of the effects of various additives and polymers on nerve growth factor microspheres

Objective: To evaluate the effects of various additives or polymers on the in vitro characteristics of nerve growth factor (NGF) microspheres.

Materials and methods: NGF microspheres were fabricated using polyethylene glycol (PEG), ovalbumin (OVA), bovine serum albumin (BSA) or glucose as protein protectors, and poly(lactide-co-glycolide) (PLGA) or poly(lactic acid) (PLA)/PLGA blends as encapsulation materials.

Results: Encapsulation efficiencies of the NGF microspheres with various additives or polymers were not more than 30%. A comparative study revealed that OVA was somewhat superior over others, and was thus chosen as the protective additive in subsequent experiments. Polymer analysis showed that NGF release from 1:1 PLA (η?=?0.8):PLGA (75/25, η?=?0.45) microspheres lasted for 90?d with a burst release rate of 12.7%. About 40% of the original bioactivity was retained on the 28th day, while 10% was left on the 90th day.

Discussion and conclusion: The combination of OVA as an additive and the PLA/PLGA blend as the coating matrix is suitable for encapsulation of NGF in microspheres for extended release.     

Comment on the paper by J. Thomas Joseph Prakash, S. Kumararaman, “Growth and characterization of l-asparagine thiourea monohydrate (LATM): A nonlinear optical single crystal”, Materials Letters 62(2008) 4003-4005

It is argued that the conclusion of the authors of the title paper on obtaining of a new crystal l-asparagine thiourea monohydrate is erroneous. The authors actually have obtained well known l-asparagine monohydrate crystal.     

Tauschwirtschaft, Reputationsökonomie, Bürokratie

  Changing Economies. Exchange, Symbolic Capital and Bureaucracy in the Radium Market before the First World War The newly discovered radioactive substance radium was the most important research object in the early years of radioactivity research. It was very promising with regard to medicine and a notable curiosity. Radium, however, was not easy to get hold off - at least not in all times and places. This paper analyses the changing structure of the radium market up to 1914. During the first years, radium could be acquired only through personal relationships to those few researchers who were capable of producing it themselves. When the first chemical companies decided to begin radium production, radium could be bought (almost) like other commodities. This was not to last for long, however, since the Austrian government had already stopped exports of the pertinent raw material by 1904. The mineral was exploited by the Austrian academy of sciences, which distributed the radium obtained from it to those researchers who seemed the most deserving. When Austrian radium production increased, radium became a commodity again, albeit it was traded within highly monopolized structures. Radium’s astronomical price made the importance of a standard and reliable measurement procedures acutely felt and soon transformed the selling and buying of radium into a highly bureaucratized scientific procedure. These drastically changing conditions under which radium had to be obtained make clear that chemical substances, like instruments, have a history of their own.

     

Impact of surfactant selection on the formulation and characterization of microparticles for pulmonary drug delivery

The effect of suspension stabilizers, internal aqueous phase volume and polymer amount were investigated for the production of protein loaded poly(d,l?lactide-co-glycolide) (PLGA) microparticles suitable for pulmonary drug delivery. PLGA microparticles were produced adopting water-in-oil-in-water (W/O/W) solvent evaporation technique and were investigated for surface morphology, particle size, encapsulation efficiency (EE%) and in-vitro release profile. Porous surface morphologies with a narrow size distribution were observed when employing 0.5?ml internal aqueous phase; 23.04?µm (±0.98), 15.05?µm (±0.27) and 22.89?µm (±0.41) for PVA, Tween 80 and oleic acid. Porous microparticles exhibited increased size and reduction in EE% with increasing internal aqueous phase, with non-porous microparticles produced when adopting 2.0?ml internal aqueous phase. The selection of stabilizer influences the size of the pores formed thus offers potential for the aerodynamic properties of the microparticles to be manipulated to achieve suitable aerosolization characteristics for pulmonary delivery of proteins.     

Acceptability and validity of older driver screening with the DrivingHealth Inventory

Research has indicated that technology can be effectively used to identify high-risk older drivers. However, adaptation of such technology has been limited. Researchers debate whether older drivers represent a safety problem as well as whether they should be screened for driving fitness. The present study examined how drivers feel regarding technological screening and mandatory state testing. The validity and acceptability of a new technological screening battery for identifying high-risk drivers, the DrivingHealth Inventory (DHI), was also evaluated. In a sample of 258 Alabama drivers aged 18-87, older drivers performed significantly worse than younger drivers on sensory, cognitive, and physical subtests of the DHI, and older drivers with a crash history performed worse than older drivers without crashes. Regardless of age, 90% of participants supported states requiring screening for older drivers' license renewal. The majority of the participants (72%) supported use of technological screening batteries such as the DHI as a driver screening tool. Considering the acceptability and potential efficacy of the DHI, it may be a useful tool in evaluating driving fitness among older adults.     

Facile, one-step controlled synthesis of Se nanocrystals in the presence of l-tyrosine

Se with different morphologies was synthesized using l-tyrosine as reducing agent and soft template by means of hydrothermal method. The method was simple and convenient to handle. The reaction process was monitored using ultraviolet-visible spectroscopy (UV-vis) and Fourier-transform infrared spectroscopy (FTIR). The morphology and crystalline phase were determined by transmission electron microscopy (TEM), scanning electronic microscopy (SEM) and X-ray diffraction (XRD) pattern. The results show that the morphologies and the crystalline phases of Se can be easily controlled. By varying the concentration ratio of l-tyrosine to selenious acid, the morphologies and crystalline phases of Se were not changed, but the diameter of Se was different. Se nano-rods are obtained in the lower temperature, and there is a transformation of microspheres into nanorods of Se with the increase of reaction time or reaction temperature. In addition, we discuss the possible mechanism of the reduction of SeO₃²⁻ ions by l-tyrosine. The eco-friendly, biogenic synthesis strategy could be widely used for preparing inorganic/organic biocomposites.     

Prekäre Stoffe

  Precarious Matters. The Radium Economy, Episteme of Risk and the Emergence of Tracer Technique in National Socialism Following the traces of radioactive material is – as scholars have recently shown – a valuable historical approach in order to evaluate the material ’factor’ of science in action. Even though the origins of materials like radium and artificial isotopes are quite different, their circulation is interconnected. A material pathway can be drawn from the radium industry to the scientific rise of artificial isotopes as indicator substances in the 1930s, continuing to the building of networks by German scientists working for the war efforts. Also, this pathway reveals the role of radiation protection in establishing that material culture. Finally, the dynamics of material traces and institutional linkages is shown by the tracer work of biophysicists and radiation biologists working at the Genetic Department of the Kaiser Wilhelm Institute for Brain Research in Berlin and at the Institut de Chimie Nucléaire at Paris, which at that time was occupied by German troops.      

L-Aspartic acid/L-cysteine/gold nanoparticle modified microelectrode for simultaneous detection of copper and lead

This paper presents an electrochemical microsensor for simultaneous detection of copper (II) and lead (II) using an l-aspartic acid/l-cysteine/gold nanoparticle modified microelectrode. The microelectrode was fabricated by Micro Electro-Mechanical System technique. The complex of gold nanoparticles (AuNPs) and amino acid with carboxyl group was used as the selective ligand for metal ions. The microelectrode was firstly modified with AuNPs to increase the sensitive area of the working electrode. Subsequently, the AuNPs/gold electrode was modified with l-cysteine and then covalently linked with a monolayer of l-aspartic acid using glutaraldehyde. Electrochemical analysis of metal ions was achieved by using square wave voltammetry without stirring. The microsensor exhibited an excellent linear range from 5 μg L^− 1 to 2000 μg L^− 1 with the limit of detection of 1 μg L^− 1. This metal ion detection method based on l-aspartic acid/l-cysteine/gold nanoparticle modified microelectrode is simple, sensitive and it could be used for electrochemical analysis of copper (II) and lead (II).     

A Multi-Criteria Decision Analysis Technique for Stochastic Task Criticality in Project Management

Inherent in project management is the risk that a project fails to meet planned completion deadlines due to delays experienced in individual tasks. As such, certain critical tasks may be candidates for risk management (e.g., the allocation of additional resources such as labor, materials, and equipment) to prevent delays. A common means to identify such critical tasks is with the critical path method (CPM), which identifies a path of tasks in a project network that, when delayed, result in project delays. This work offers a complementary, stochastic approach to CPM that ranks tasks according to their effect on the project completion time distribution, when the distributions of task completion time are delayed. The new hybrid approach is based on the use of a Monte Carlo simulation and a multi-criteria decision analysis technique. Monte Carlo simulation allows for approximating the cumulative distribution function of the total duration of the project, while the multi-criteria decision analysis technique is used to compare and rank the tasks across percentiles of the resulting project completion time distributions. Doing so allows for different percentile weighting schemes to represent decision maker risk preferences. The suggested approach is applied to two project network examples. The examples illustrate that the proposed approach highlights some tasks as risky, which may not always lie on the critical path as identified by CPM. This is valuable for practicing managers as it allows them to properly consider their risk preferences when determining task criticality based on the distribution of project completion time (e.g., emphasizing median vs. upper tail completion time).     

Performance of the radphi detector and trigger in a high rate tagged photon beam

We describe the design and operation of a detector system for measuring all-photon decays of mesons photoproduced in a tagged photon beam with energies between 4.3 and 5.4 GeV and a flux of 5×10⁷ tagged photons per second. Photons from meson decays were detected with a lead-glass calorimeter with an energy resolution of 11% at 1 GeV. Various veto and trigger components were also present. Final states with as many as six photons were successfully detected and reconstructed.     

Evaluation of NLO susceptibilities for l-threonine amino acid single crystals using anharmonic oscillator model

Three dimensional semi-classical anharmonic oscillator model proposed by Akitt has been used to evaluate the second order and electro-optic susceptibilities of l-threonine. As the ionic contribution to the optical non-linearity for the frequency range under study was negligible, the NLO parameters were calculated by taking the contribution of electronic polarization alone. The data presented here are in reasonable agreement with the experimental ones and the results have been discussed in detail.     

Formulation and characterization of ethylcellulose microparticles containing .l-alanyl- l-glutamine peptide

Context: The l-alanyl-l-glutamine peptide (AGP) has been effective to promote acute glycemia recovery during long-term insulin-induced hypoglycemia (IIH), and the oral administration of AGP is suggested to prevent prolonged hypoglycemia, such as nocturnal hypoglycemia.

Objective: Considering the ability of AGP on glycemia recovery and AGP’s fast metabolism, the aim of current study was to obtain and characterize ethylcellulose microparticles to deliver the drug for a prolonged time.

Materials and Methods: Microparticles were prepared by simple and double emulsification/hardening method and characterized by scanning electron microscopy, thermogravimetry (TG), differential scanning calorimetry (DSC), Fourier transform infra-red (FTIR) and FT-Raman spectroscopy and in vitro release.

Results and Discussion: Spherical structures with a mean diameter between 9.30?µm and 13.19?µm were formed. TG analysis showed that the thermal stability of AGP was even more increased by encapsulation with ethylcellulose. In addition, TG, DSC, FTIR and FT-Raman analyses proved that AGP was encapsulated in a molecular way. Higher values of encapsulation efficiency were observed for the microparticles prepared by double emulsification (57.83–83.67%) than for those prepared by simple emulsification (18.37%). However, the last ones could release the peptide in a quicker and more extensive manner than those prepared by double emulsification.

Conclusion: For the first time, microparticles containing AGP were developed and exhibited prolonged in vitro release as well as protection to the drug, and it could be considered as a dosage form for patients who suffer from insulin-induced hypoglycemia and/or nocturnal hypoglycemia.     

“If there is nothing beyond the organic...”

  “If there is nothing beyond the organic...” Vererbung und Kultur an den Grenzen der Anthropologie bei Alfred L. Kroeber Als Alfred L. Kroeber Anfang des 20. Jahrhunderts daran arbeitete, die Anthropologie als akademische Disziplin zu etablieren, definierte er Kultur, aufbauend auf das bereits von seinem Lehrer Franz Boas Geleistete, als ein Ph?nomen sui generis. Damit wollte er nicht zuletzt die aufstrebende Genetik seiner Zeit für eine Koalition gegen den damals in Nordamerika vorherrschenden Hereditarianismus gewinnen. Das Ziel war, für die Anthropologie einen klar umschriebenen Raum innerhalb der akademischen Arbeitsteilung zu schaffen. Um die Grenzlinien dieser Arbeitsteilung zu festigen, überschritt Kroeber sie jedoch in Richtung Biologie: Er entwickelte seinen Begriff der Kultur in enger Anlehnung an den Begriff der Vererbung – als unabh?ngig von Vererbung (Kultur als superorganisch) und gleichzeitig als analog zu Vererbung (Kultur als neue Art der Vererbung). Im Beitrag werden die prek?ren Grenzlinien der Anthropologie zu Beginn des 20. Jahrhunderts kurz zusammengefasst, um dann Kroebers Ideen zum Kulturkonzept zu pr?sentieren, wobei der Fokus auf den Einfluss gelegt wird, den die ver?nderte Landschaft um den Begriff der Vererbung auf seinen Kulturbegriff hatte. Auf der Grundlage des historischen Fallbeispiels werden zwei allgemeine Schlussfolgerungen gezogen: erstens, dass der Begriff der Kultur verschiedene Rollen in Erkl?rungen der menschlichen Existenzweise spielen kann, und zweitens, dass der Weismann’sche Begriff der harten Vererbung keine eindeutig einseitige historische Wirkung auf das Erstarken des Hereditarianismus zu Beginn des 20. Jahrhunderts in Nordamerika hatte, sondern auch einen Kroeber’schen Kulturbegriff zu etablieren half. Kultur konnte damit unabh?ngig von Vererbung gedacht werden.

     

Joint interval reliability for Markov systems with an application in transmission line reliability

We consider Markov reliability models whose finite state space is partitioned into the set of up states and the set of down states . Given a collection of k disjoint time intervals I_ℓ=[t_ℓ,t_ℓ+x_ℓ], ℓ=1,…,k, the joint interval reliability is defined as the probability of the system being in for all time instances in I₁I_k. A closed form expression is derived here for the joint interval reliability for this class of models. The result is applied to power transmission lines in a two-state fluctuating environment. We use the Linux versions of the free packages Maxima and Scilab in our implementation for symbolic and numerical work, respectively.     

Self-assembly of silver nanoparticles into dendritic flowers from aqueous solution

Similar to folding of proteins into three-dimensional (3D) structure, self-assembly of metallic nanoparticles (NPs) into dendritic or other supramolecular structures is of greater interest, yet less understood. We observed spontaneous, template-free organisation of silver NPs into 3D, dendritic, elegant, flower-like structures from an aqueous solution containing AgNO₃ and L-cysteine (Cys). The resultant NPs and dendritic structures were characterised using UV–Vis spectroscopy and scanning and transmission electron microscopy. The process initiated most likely by diffusion-limited aggregation in the liquid phase, which were further grown into elegant, dendritic flowers probably by evaporation of residual wetting layer of larger NPs. Electrostatic attraction between –COO^? and –NH₃ ⁺ groups of L-Cys on the surface of silver NPs may also have a role in their growth.     

Facile and controllable one-step fabrication of selenium nanoparticles assisted by l-cysteine

A simple and solution-phase approach for large-scale synthesis of selenium nanoparticles (Nano-Se) by reducing sodium selenite (Na₂SeO₃) with l-cysteine has been demonstrated in this study. l-cysteine was used as both the reducing agent and surface modifier to control the formation of Nano-Se. The effects of reactant concentrations and ratios, and reaction time on the size and stability of Nano-Se were also investigated. The morphology and chemical composition of Nano-Se were characterized using various spectroscopic and microscopic methods. The results showed that varying the concentration ratio of l-cysteine to Na₂SeO₃ could control the diameter and morphology of Nano-Se, but not affecting their crystalline phases and chemical compositions. Monodisperse and homogeneous spherical Nano-Se with an average diameter of about 100 nm could be synthesized with the concentration ratio of l-cysteine to Na₂SeO₃ at 4:1. A striking feature of the as-synthesized Nano-Se was their good stability when dispersed in the reaction solutions, which indicates their potential in medical applications.     

Techniken der Vermittlung

  Techniques of Mediation. Chemistry as a Combination of Work, Teaching and Research: the Case of J. F. A. G?ttling A typical career of a chemist in Germany around 1800 consisted of being trained as an apothecary, followed by an occupation as a professor at a university or another institution of higher education. These conditions deeply influenced the concept and the practice of chemistry as a science. Johann Friedrich August G?ttling is an intriguing example for merging education and daily duties of teaching with the self-image of a scientific chemist. He linked chemical teaching, work, and research by using different hybrid media, such as the Almanach oder Taschenbuch für Scheidekünstler und Apotheker, a stove specifically designed for the narrow student’s room, portable laboratories, a pharmaceutical boarding school and textbooks. This allowed him to practice three different forms of chemistry as a science. A “socio-epistemological diagram” of German chemistry around 1800 shows that these forms neatly corresponded to the then predominant three-level epistemology. In particular, the concept of a chemical fact served to link pharmaceutical practice with teaching practice, while granting only the chemistry done by professors the status of a science.

     

Intermolecular Interaction of [60]Fullerene with Tröger's Base Analogues

Tröger's base (TB, 1) and its analogues were synthesized and were subject to the titration experiments to evaluate their ability of supramolecular complexation with C₆₀. Results demonstrate clearly that the fluorene-based TB analogue (2) and the bioctylfluorene-based TB analogue (3) show 1:1 binding with C₆₀ to form the corresponding complexes while TB 1 does not. Titration experiments exhibited that the association constant (K_ass) of 3/C₆₀ (48.1 ± 7.9 M ^?1) was larger than that of 2/C₆₀ (13.7 ± 1.4 M ^?1)_. The formation of the 1:1 binding complexes 2/C₆₀ and 3/C₆₀ was also confirmed by MALDI-TOF mass spectrometry. Theoretical calculations suggest that 2 and 3 have appropriate cavities to embrace C₆₀. These findings indicate that not only the π/π interaction between the fluorene moieties and the C₆₀ surface but also the CH/π interaction between the octyl groups and the C₆₀ surface serve efficiently in the supramolecular complexation with C₆₀.     

Inherent safety concepts in nuclear power reactors

Different inherent safety concepts being considered in fast and thermal reactors are presented after outlining the basic goals of nuclear reactor safety, the ‘defence in depth’ philosophy to achieve these goals and the characteristics affecting the safety of liquid metal fast breeder and light water reactors. The inherent safety potential of fast reactors with respect to different sizes and types of fuel is also discussed. Finally, the approach proposed for the Indian Prototype Fast Breeder Reactor (Pfbr), which is in the detailed design stage, is also presented.