The bevel effect: a prospective, randomized investigation into needle design in dental intraligamentary anesthesia.

OBJECTIVES: This in vivo study aimed to assess the impact of needle bevel design on puncture pain, anesthetic success, and mechanical deformations in intraligamentary injection (ILA) cases, comparing a short triple facet cut (STF) to a triple lancet cut (TL) after single or repetitive use. MATERIALS AND METHODS: In a prospective single-blind trial, 200 ILA needles (STF, n = 100; TL, n = 100) were randomly assigned for dental procedures. Patients received ILA either with STF or TL needles, used once (group A; n = 50 each) or repeatedly (group B; n = 50). Puncture pain was assessed using a numerical rating scale (NRS). Anesthetic success was determined via cold spray (yes/no), and scanning electron microscopy (SEM) analyzed needle tip deformations. RESULTS: Puncture pain did not significantly differ between STF and TL, regardless of needle use or injection area. Success rates were comparable in single use (82% STF vs. 79% TL; p > 0.05). For repetitive use, STF exhibited a significantly higher success rate (80% vs. 69%; p = 0.012). Mechanical deformations were prevalent in 97.5% of needles, with TL showing greater deformations than STF after single and repeated uses. Barbs were more common in TL (90/100) than STF (84/100), with a higher relative risk for barbed-like deformation in TL (RR single use: 1.26; p < 0.001; multiple use: 7.87, p < 0.001). CONCLUSIONS: The short triple facet-designed bevel demonstrated significantly less mechanical deformation, suggesting potential advantages in maintaining needle lumen patency. CLINICAL RELEVANCE: The intraligamentary needle bevel design is linked to mechanical deformation and anesthetic success after repetitive use, but not to puncture pain.

Charge transfers and charged defects in WSe2/graphene-SiC interfaces.

We report on Kelvin probe force microscopy (KPFM) and density functional theory (DFT) investigations of charge transfers in vertical heterojunctions between tungsten diselenide (WSe2) layers and graphene on silicon carbide substrates. The experimental data reveal the existence of an interface dipole, which is shown by DFT to originate from the neutralization of the graphene n-doping by an electron transfer towards the transition metal dichalcogenide (TMD) layer. The relative vacuum level shift probed by KPFM between the TMD and the substrate stays constant when passing from monolayer to bilayer graphene, which confirms that the Schottky-Mott model can be rigorously applied to these interfaces by taking into account the charge transfer from the substrate to the TMD. DFT calculations show that the first TMD layer absorbs almost all the excess charges contained in the graphene, and that the second TMD layer shall not play a significant role in the electrostatics of the system. Negatively charged defect at the TMD edges contribute however to the electrostatic landscape probed by KPFM on both TMD layers.

Influence of needle bevel design on injection pain and needle deformation in dental local infiltration anaesthesia - randomized clinical trial.

The aims of this in vivo study were to evaluate the impact of needle bevel design on patients' pain perception and the mechanical deformation of the needle tip after the injection. In a prospective single-blinded trial, 150 patients received conventional infiltration anaesthesia for dental treatment by one examiner. Patients were randomized for one out of three different needle bevel types (scalpel-designed bevel needle (SB), n=50; triple bevel needle (TB), n=50; regular bevel needle (RB), n=50). Subjects' self-reported injection pain perception was evaluated using a numeric rating scale (NRS). For each needle tip, deformations after single use were measured using SEM. A significant lower injection pain level was found in SB (mean 2.1±1.2) than in TB (mean 3.5±1.6;) and RB (mean 3.4±1.0; all P<0.001). A needle deformation was detected in about 97.3% of all needles (SB 50/50, TB 50/50, and RB: 46/50). A higher number of barbs were found in SB (29/50) versus TB (17/50) and RB (19/50). For dental local infiltration anaesthesia, injection needles with a scalpel-designed bevel demonstrated significantly less injection pain. Needle tip deflections after anaesthetic agent infiltration, especially barbed hooks on the non-cutting edge may result in greater soft tissue trauma.

Evidence for spin-to-charge conversion by Rashba coupling in metallic states at the Fe/Ge(111) interface.

The spin-orbit coupling relating the electron spin and momentum allows for spin generation, detection and manipulation. It thus fulfils the three basic functions of the spin field-effect transistor. However, the spin Hall effect in bulk germanium is too weak to produce spin currents, whereas large Rashba effect at Ge(111) surfaces covered with heavy metals could generate spin-polarized currents. The Rashba spin splitting can actually be as large as hundreds of meV. Here we show a giant spin-to-charge conversion in metallic states at the Fe/Ge(111) interface due to the Rashba coupling. We generate very large charge currents by direct spin pumping into the interface states from 20 K to room temperature. The presence of these metallic states at the Fe/Ge(111) interface is demonstrated by first-principles electronic structure calculations. By this, we demonstrate how to take advantage of the spin-orbit coupling for the development of the spin field-effect transistor.

Switchable stereocontrolled divergent synthesis induced by aza-Michael addition of deactivated primary amines under acid catalysis.

Switchable tandem intramolecular aza-Michael/Michael and double aza-Michael reactions allow the oriented synthesis of highly functionalised cyclic skeletons. Conjugate addition of deactivated anilines triggers chemo- and stereo-divergent ring-closure reaction pathways with a striking selectivity depending on reaction conditions.

A short synthesis of antimalarial peroxides.

A concise and efficient synthesis of two simplified diastereomeric analogues of a natural peroxide is presented. Both compounds could be isolated in high purity and fully identified. They exhibited moderate antimalarial activity.

New cyclohexadienone derivatives: preparation and chiral discrimination in high-pressure Diels-Alder cycloadditions.

A wide range of cyclohexadienones has been synthesised in order to study their reactivity and their regio- and stereoselectivity with the enantiopure diene 1 under high-pressure conditions. Computational investigations were used to point out some parameters which affect the reactivity in this high chiral discrimination process. In addition, the resulting [4+2] cycloadducts allowed the preparation of new polyfunctional cyclohexenone derivatives.

Total synthesis and conformational studies of hapalosin, N-desmethylhapalosin and 8-deoxyhapalosin.

Hapalosin (2), a 12-membered cyclic depsipeptide possessing MDR-reversing activity, and analogues (3) and (4) have been synthesized using macrolactamization as an important ring-forming step. Three building blocks: (2S,3R)-3-(tert-butyldimethylsilyloxy)-2-methyl-decanoic acid (13), benzyl (S)-2-hydroxy-3-methylbutanate (14), and (4S,3R)-4-(benzyloxycarbonyl-methylamino)-3-methoxymethoxy-5-pheny l-pentanoic acid (28) were prepared from Evans's chiral imide (9), L-valine, and L-N-Boc phenylalanine (17), respectively, and were assembled together by applying twice Yamaguchi's coupling methodology. A new and efficient selective N-methylation of gamma-hydroxy-beta-amino ester taking advantage of the vicinal amino alcohol function was uncovered in the course of this study. Thus, treatment of compound 19 with HCHO in the presence of catalytic amount of pTsOH followed by reduction (NaBH3CN, TFA, CH2Cl2) of the so-formed oxazolidine 24 gave the N-methylated product 25. Furthermore, a dual role of oxazolidine as protecting group of vicinal amino alcohol and latent N-methyl function was established which allowed synthesizing both hapalosin (2) and N-desmethylhapalosin (3) from the same linear precursor 32 in a step-efficient and atom economic way. In contrast to hapalosin (2) and N-desmethyl analogue (3), the amide bond of 8-deoxy hapalosin (4) exists at room temperature (CDCl3) exclusively in s-cis conformation as evidenced by NOE studies. This observation has been explained on the basis of computational studies. No significant MDR reversing activity of 8-deoxy hapalosin (4) was observed in K562 R and S/Adriblastine against human erythroleucemic cell lines indicating thus the important contribution of hydroxy group to the bioactivity of hapalosin.

Lack of clinical relevance in routine final subcultures of radiometrically negative BACTEC blood culture vials.

During a 38-month period, 10,106 blood specimens were received in the laboratory for culture. These were inoculated into 26,424 vials and processed using the BACTEC radiometric detection system. Of these vials, 1,914 were eventually found to be microbiologically positive. Isolates from 836 vials were judged to be contaminants. In the remaining 1,078 vials, growth was first detected visually or radiometrically in 1,062 and by final subculture in 16. Growth from these sixteen bottles represented 12 clinically significant bacteremic episodes in as many patients. In nine of these episodes, other culture vials from the same patient were positive radiometrically. Therefore, 358 of 361 (99.2%) bacteremic episodes were detected without the benefit of routine final subcultures. The three patients whose bacteremia was missed were diagnosed clinically and placed on appropriate therapy prior to the detection of the bacteremias by final subculture.