Enzymatic ligation creates discrete multinanoparticle building blocks for self-assembly

Enzymatic ligation of discrete nanoparticle-DNA conjugates creates nanoparticle dimer and trimer structures in which the nanoparticles are linked by single-stranded DNA, rather than by double-stranded DNA as in previous experiments. Ligation was verified by agarose gel and small-angle X-ray scattering. This capability was utilized in two ways: first, to create a new class of multiparticle building blocks for nanoscale self-assembly and, second, to develop a system that can amplify a population of discrete nanoparticle assemblies.     

P123-assisted hydrothermal synthesis and characterization of rectangular parallelepiped and hexagonal prism single-crystalline mgo with three-dimensional wormholelike mesopores

By adopting the strategy of dissolution-recrystallization under hydrothermal conditions (at 240 degrees C for 72 h) in the presence of a triblock copolymer (Pluronic P123), we fabricated nano- and microparticles of single-crystalline MgO of rectangular parallelepiped and hexagonal prism morphologies. The MgO crystallites display three-dimensional wormholelike mesopores and have a surface area as high as 298 m(2)/g even after calcination at 550 degrees C for 3 h.     

LC-MS/MS biopharmaceutical glycoanalysis: identification of desirable reference material characteristics

Glycosylation, the enzymatic addition of carbohydrates to a protein, is one of the most abundant post-translational modifications found in nature. There is variability in the number, location, and identity of glycans attached. As a result, a glycoprotein consists of a number of glycoforms with different combinations of glycans, potentially resulting in different stability, toxicity, and activity. This is especially important in the biopharmaceutical industry where product consistency and safety are vital. Glycoprotein analysis involves numerous mass spectrometry based techniques, each of which provides various aspects of characterization. The current paper describes two commonly used analytical techniques for glycoprotein characterization. In one experiment, nonspecific proteolysis is combined with a two-tiered mass spectrometry approach (MALDI-TOF and LC-MS/MS) to gain glycosylation site and glycan identity. In a second approach, glycans were enzymatically released, labeled with a fluorescent dye, and analyzed using LC-Fluorescence-MS/MS to give glycan identification and relative quantification. The type and degree of information yielded by each method is assessed in an effort to identify desired reference material characteristics for improving biopharmaceutical glycoanalysis.     

A data mining framework for product and service migration analysis

With new technologies or products invented, customers migrate from a legacy product to a new product from time to time. This paper discusses a time series data mining framework for product and service migration analysis. In order to identify who migrate, how migrations look like, and the relationship between the legacy product and the new product, we first discuss certain characteristics of customer spending data associated with product migration. By exploring interesting patterns and defining a number of features that capture the associations between the spending time series, we develop a co-integration-based classifier to identify customers associated with migration and summarize their time series patterns before, during and after the migration. Customers can then be scored based on the migration index that integrates the statistical significance and business impact of migration customers. We illustrate the research through a case study of internet protocol (IP) migration in telecommunications and compare it with likelihood-ratio-based tests for change point detections.     

Gold nanostructures: engineering their plasmonic properties for biomedical applications

The surface plasmon resonance peaks of gold nanostructures can be tuned from the visible to the near infrared region by controlling the shape and structure (solid vs. hollow). In this tutorial review we highlight this concept by comparing four typical examples: nanospheres, nanorods, nanoshells, and nanocages. A combination of this optical tunability with the inertness of gold makes gold nanostructures well suited for various biomedical applications.     

A density functional study on beryllium-doped carbon dianion clusters CnBe2- (n = 4-14)

Making use of the software of molecular graphics, we designed numerous models of C(n)()Be(2-) (n = 4-14). We carried out geometry optimization and calculation on vibration frequency by means of the B3LYP density functional method. After comparison of structure stability, we found that the ground-state isomers of C(n)()Be(2-) (n = 4-14) are linear with the beryllium atom located inside the C(n)() chain. When a side carbon chain is with an even number of carbon atoms, it is polyacetylene-like, whereas when a side chain is with an odd number of carbon atoms, it is cumulene-like. The C(n)Be(2-) (n = 4-14) clusters with an even number of carbon atoms are more stable than that with an odd number of carbon atoms, matching the peak pattern observed in accelerator mass spectrometry (AMS) and Coulomb Explosion Imaging (CEI) investigations of C(n)()Be(2-) (n = 4-14). The trend of such odd/even alternation is explained based on concepts of bonding characteristics, electronic configuration, electron detachment, and incremental binding energy.     

Modified lithium borohydrides for reversible hydrogen storage (2)

This paper reports the results of the effort to destabilize lithium borohydride for reversible hydrogen storage. Various metals, metal hydrides, and metal chlorides were selected and evaluated as destabilization agents for reducing dehydriding temperatures and improving dehydriding/rehydriding reversibility. The most effective material was LiBH4 + 0.2MgCl2 + 0.1TiCl3 which starts desorbing 5 wt % of hydrogen at 60 degrees C and can be rehydrogenated to 4.5 wt % at 600 degrees C and 70 bar. X-ray diffraction and Raman spectroscopic analysis show the interaction of LiBH4 with additives and the unusual change of B-H stretching.     

Peculiarities of Electrochemical Bismuth Film Formation in the Presence of Bromide and Heavy Metal Ions

Bi films were deposited on glassy carbon electrode from solutions with and without KBr. The morphology of both types of the films was characterized by scanning electron microscopy (SEM), and their electrochemical behavior was studied by square wave (SWV) and cyclic voltammetry (CV). Bi films were also co‐deposited with common analyte‐heavy‐metals in the presence of KBr and these films also were characterized by SEM, SWV and CV in order to understand the formation of the mixed metal films. All films studied had a different morphology. Bromide addition made the Bi films more compact and uniform, whereas Pb catalyzed Bi film deposition.     

Dolphin biosonar signals measured at extreme off-axis angles: Insights to sound propagation in the head

Biosonar signals radiated along the beam axis of an Atlantic bottlenose dolphin resemble short transient oscillations. As the azimuth of the measuring hydrophones in the horizontal plane progressively increases with respect to the beam axis the signals become progressively distorted. At approximately ±45°, the signals begin to divide into two components with the time difference between the components increasing with increasing angles. At ±90° or normal to the longitudinal axis of the animal, the time difference between the two pulses measured by the hydrophone on the right side of the dolphin's head is, on average, ～11.9?μs larger than the time differences observed by the hydrophone on the left side of the dolphin's head. The center frequency of the first pulse is generally lower, by 33-47?kHz, than the center frequency of the second pulse. When considering the relative locations of the two phonic lips, the data suggest that the signals are being produced by one of the phonic lips and the second pulse resulting from a reflection within the head of the animal. The generation of biosonar signals is a complex process and the propagation pathways through the dolphin's head are not well understood.     

Highly Twisted Thermally Activated Delayed Fluorescence (TADF) Molecules and Their Applications in Organic Light-Emitting Diodes (OLEDs)

Thermally activated delayed fluorescence (TADF) materials have attracted great potential in the field of organic light-emitting diodes (OLEDs). Among thousands of TADF materials, highly twisted TADF emitters have become a hotspot in recent years. Compared with traditional TADF materials, highly twisted TADF emitters tend to show multi-channel charge-transfer characters and form rigid molecular structures. This is advantageous for TADF materials, as non-radiative decay processes can be suppressed to facilitate efficient exciton utilization. Accordingly, OLEDs with excellent device performances have also been reported. In this Review, we have summarized recent progress in highly twisted TADF materials and related devices, and give an overview of the molecular design strategies, photophysical studies, and the performances of OLED devices. In addition, the challenges and perspectives of highly twisted TADF molecules and the related OLEDs are also discussed.