Superconducting Electrometer Based on the Resistively Shunted Bloch Transistor

We have fabricated the Bloch transistor shunted on-chip by a small-sized Cr resistor with Rs about 1 kOhm. The Bloch transistor normally consists of two small Josephson junctions connected in series, which in our case have been replaced by two superconducting interferometer loops, each with two junctions in parallel. A capacitively coupled gate is supplied to control the induced charge of the small intermediate electrode (island) of the transistor. The measured I-V curves show no hysteresis and correspond to the operation of a effective Josephson junction at the high-damping and strong-noise limits. The critical current of the system was found to be close to its nominal value, that is in accordance with the electromagnetic environment theory. The I-V curves were modulated by the gate with a period of e and a maximum swing of about 2 /mu_V. Such rather moderate modulation results from the Josephson-to- charging energies ratio, Ej/Ec about 9, in our sample being far from its optimum value of 0.3 up to 1.Comment: To be published in IEEE Transactions on Applied Superconductivity, June 199

Storage capabilities of a 4-junction single electron trap with an on-chip resistor

We report on the operation of a single electron trap comprising a chain of four Al/AlOx/Al tunnel junctions attached, at one side, to a memory island and, at the other side, to a miniature on-chip Cr resistor R=50 kOhm which served to suppress cotunneling. At appropriate voltage bias the bi-stable states of the trap, with the charges differing by the elementary charge e, were realized. At low temperature, spontaneous switching between these states was found to be infrequent. For instance, at T=70 mK the system was capable of holding an electron for more than 2 hours, this time being limited by the time of the measurement.Comment: 3 pages of text and 2 figure

Ultraviolet cut off and Bosonic Dominance

We rederive the thermodynamical properties of a non interacting gas in the presence of a minimal uncertainty in length. Apart from the phase space measure which is modified due to a change of the Heisenberg uncertainty relations, the presence of an ultraviolet cut-off plays a tremendous role. The theory admits an intrinsic temperature above which the fermion contribution to energy density, pressure and entropy is negligible.Comment: 12 pages in revtex, 2 figures. Some coefficients have been changed in the A_2 model and two references adde

End-joining long nucleic acid polymers

Many experiments involving nucleic acids require the hybridization and ligation of multiple DNA or RNA molecules to form a compound molecule. When one of the constituents is single stranded, however, the efficiency of ligation can be very low and requires significant individually tailored optimization. Also, when the molecules involved are very long (>10 kb), the reaction efficiency typically reduces dramatically. Here, we present a simple procedure to efficiently and specifically end-join two different nucleic acids using the well-known biotin–streptavidin linkage. We introduce a two-step approach, in which we initially bind only one molecule to streptavidin (STV). The second molecule is added only after complete removal of the unbound STV. This primarily forms heterodimers and nearly completely suppresses formation of unwanted homodimers. We demonstrate that the joining efficiency is 50 ± 25% and is insensitive to molecule length (up to at least 20 kb). Furthermore, our method eliminates the requirement for specific complementary overhangs and can therefore be applied to both DNA and RNA. Demonstrated examples of the method include the efficient end-joining of DNA to single-stranded and double-stranded RNA, and the joining of two double-stranded RNA molecules. End-joining of long nucleic acids using this procedure may find applications in bionanotechnology and in single-molecule experiments

Systematic review and meta-analysis on physical barriers to prevent root dentin demineralization.

The present review systematically analyzed in vitro and in situ studies investigating physical diffusion barriers (sealants, desensitizer or adhesives) to prevent the development or the progression of root (dentin) demineralization. Three electronic databases (PubMed-Medline, CENTRAL, Ovid-EMBASE) were screened for studies from 1946 to 2022. Cross-referencing was used to identify further articles. Article selection and data abstraction were done in duplicate. Languages were not restricted. The type of outcome was not restricted, and their mean differences (MD) were calculated using fixed- or random-effects models. Risk of Bias was graded using Risk of Bias 2.0 tool. From 171 eligible studies, 34 were selected for full-text analysis evaluating 69 different materials, and 17 studies-still evaluating 36 different materials-were included (3 in situ and 14 in vitro). Ten studies evaluated desensitizers; 8 adhesives; and 1 infiltration. Meta-analyses were possible for all 17 studies. Meta-analyses revealed that lesion depth after no treatment was significantly higher than after the application of single-step adhesives (MD[95%CI] = - 49.82[- 69.34; - 30.30]) and multi-step adhesives (MD[95%CI]=-60.09 [-92.65, -27.54]). No significant differences in the lesion depth increase between single- and multi-step adhesives could be observed (MD[95%CI]=30.13 [-21.14, 81.39]). Furthermore, compared to no treatment the increase of the lesion depth was significantly hampered using desensitizers (MD[95%CI] = - 38.02[- 51.74; - 24.31]). Furthermore, the included studies presented unclear or high risk. A physical diffusion barrier can significantly hamper the increase of lesion depth under cariogenic conditions. Furthermore, multi-step adhesives seem not to be more effective than single-step adhesives. However, this conclusion is based on only few in vitro and in situ studies

What is the Role of Acid-Acid Interactions in Asymmetric Phosphoric Acid Organocatalysis? A Detailed Mechanistic Study using Interlocked and Non-Interlocked Catalysts

Organocatalysis has revolutionized asymmetric synthesis. However, the supramolecular interactions of organocatalysts in solution are often neglected, although the formation of catalyst aggregates can have a strong impact on the catalytic reaction. For phosphoric acid based organocatalysts, we have now established that catalyst-catalyst interactions can be suppressed by using macrocyclic catalysts, which react predominantly in a monomeric fashion, while they can be favored by integration into a bifunctional catenane, which react mainly as phosphoric acid dimers. For acyclic phosphoric acids, we found a strongly concentration dependent behavior, involving both monomeric and dimeric catalytic pathways. Based on a detailed experimental analysis, DFT-calculations and a direct NMR-based observation of the catalyst aggregates, we could demonstrate that intermolecular acid-acid interactions have a drastic influence on the reaction rate and stereoselectivity of the asymmetric transfer-hydrogenation catalyzed by chiral phosphoric acids