Uncovering the Stoichiometry of Pyrococcus furiosus RNase P,a Multi‐Subunit Catalytic Ribonucleoprotein Complex,by Surface‐Induced Dissociation and Ion Mobility Mass Spectrometry

We demonstrate that surface‐induced dissociation (SID) coupled with ion mobility mass spectrometry (IM‐MS) is a powerful tool for determining the stoichiometry of a multi‐subunit ribonucleoprotein (RNP) complex assembled in a solution containing Mg²⁺. We investigated Pyrococcus furiosus (Pfu) RNase P, an archaeal RNP that catalyzes tRNA 5′ maturation. Previous step‐wise, Mg²⁺‐dependent reconstitutions of Pfu RNase P with its catalytic RNA subunit and two interacting protein cofactor pairs (RPP21⋅RPP29 and POP5⋅RPP30) revealed functional RNP intermediates en route to the RNase P enzyme, but provided no information on subunit stoichiometry. Our native MS studies with the proteins showed RPP21⋅RPP29 and (POP5⋅RPP30)₂ complexes, but indicated a 1:1 composition for all subunits when either one or both protein complexes bind the cognate RNA. These results highlight the utility of SID and IM‐MS in resolving conformational heterogeneity and yielding insights on RNP assembly.     

Synthesis,Structure, Photoluminescence,and Theoretical ­Calculation of an rtl‐type Zinc(II) Compound with Linear Trinuclear [Zn3(COO)4(μ2‐H2O)2] Subunits

The zinc(II) coordination polymer [Zn₃(BPT)₂(μ₂‐H₂O)₂(H₂O)₂]_n · n(DMA) ( 1 ) (H₃BPT = biphenyl‐3,4′,5‐tricarboxylic acid, DMA = N,N′‐dimethylactamide) was obtained by the solvothermal reaction of H₃BPT with Zn(NO₃)₂ in DMA/H₂O mixed solvent. Single crystal X‐ray analysis reveals that compound 1 has a complicated 3D framework containing linear trinuclear [Zn₃(COO)₄(μ₂‐H₂O)₂] clusters as building subunits, which can be simplified into a (3,6)‐connected rtl topological network with the Schläfli symbol {4.6²}₂{4².6¹⁰.8³}. The calculated results of total and partial density of states (DOS) indicate that the luminescence of 1 mainly originates from intraligand charge transfer.     

Palladium‐Catalyzed C(sp3)?H Activation: A Facile Method for the Synthesis of 3,4‐Dihydroquinolinone Derivatives

3,4‐Dihydroquinolinones were synthesized by the palladium‐catalyzed, oxidative‐addition‐initiated activation and arylation of inert C(sp³) H bonds. Pd(OAc)₂ and P(o‐tol)₃ were used as the catalyst and ligand, respectively, to improve the efficiency of the reaction. A further advantage of this reaction is that it could be performed in air. A relatively rare seven‐membered palladacycle was proposed as a key intermediate of the catalytic cycle.     

Recombination analysis of autosomal short tandem repeats in Chinese Han families

Recombination fractions between forensic STRs can be extrapolated from the International HapMap Project, but the concordance between recombination fractions predicated from genetic maps and derived from observation of STR transmissions in families is still ambiguous for autosomal STRs because of limited family studies. Therefore, the main goal of this study is to compare recombination fractions estimated by pedigree analysis with those derived from HapMap phase SNP data. Genotypes of nine autosomal STR pairs (TPOX‐D2S1772, D5S818‐CSF1PO, D7S3048‐D7S820, D8S1132‐D8S1179, TH01‐D11S2368, vWA‐D12S391, D13S325‐D13S317, D18S51‐D18S1364, and D21S11‐PentaD) from 207 two‐generation families with two to five children (the number of families with five, four, three, and two children was 2, 3, 20, and 182, respectively) were used to analyze the recombination. The linkage analysis showed that significant linkage was observed at six STR pairs (D5S818‐CSF1PO, D8S1132‐D8S1179, TH01‐D11S2368, vWA‐D12S391, D13S325‐D13S317, and D18S51‐D18S1364) with genetic distances <36.22 cM in HapMap. Their recombination fractions calculated from family data were very close to those derived from HapMap. However, three STR pairs of TPOX‐D2S1772, D7S3048‐D7S820, and D21S11‐PentaD showed no significant linkage with genetic distances from 43.38 to 91.49 cM. Our results indicate that recombination fractions extrapolated from HapMap can provide a substitute if empirical data are unavailable for the linkage STR pair with a genetic distance spanned <36.22 cM.     

Experimental and computational studies of molecules with close,non-bonded hydrogen–hydrogen contacts: common computational methods grossly overestimate some ‘through-space’ NMR scalar coupling constants

The NMR spin–spin scalar coupling constants (J_HH's) of closely contacting, but non-bonded hydrogen atoms in a series of highly strained molecules (including a new in,in-cyclophane made specifically for this study) have been examined both experimentally and computationally. The experimental J_HH's are invariably quite small (0.1–0.6 Hz), but common DFT methods with modest basis sets nearly always overestimate these values, by factors of 10–30, and even with quite large basis sets (up to cc-pVQZ) the J_HH's of two of the molecules are overestimated by a factor of 10 or more. Possible reasons for these discrepancies are discussed.     

Two novel polycyclic spiro lignans from Gymnotheca involucrata

Two novel lignans, gymnothespirolignans A (1) and B (2), possessing a rare polycyclic spiro skeleton, were isolated from the endemic plant of Gymnotheca involucrata Pei. Their structures were determined by spectroscopic evidences and the absolute configurations were confirmed by single crystal X-ray diffraction analysis. Compounds 1 and 2 showed promising antiviral activities against RSV with an IC₅₀ value of 31.87 and 17.51 μM, respectively.     

A Monte Carlo code to get response spectrum of ions for Neutron Depth Profiling

This paper presents a Monte Carlo code to get response spectrum of ions for the Neutron Depth Profiling (NDP) technique called Monte Carlo NDP (MC-NDP) that simulates the behavior of ions transmitted through a sample matrix and generates the energy spectrum for a specified detector. The MC-NDP model is based on the Ziegler–Biersack–Littmark Model, but incorporates the advantages of TRIM and CORTEO. The Impulse Approximation method is used to determine the flight length with the indexical interpolation method rather than the Magic algorithm for the scattering angle between ions and nucleus. This makes MC-NDP more efficient and convenient to simulate entire ion histories by a Monte Carlo approach. MC-NDP’s results agree well with both TRIM results and the experimental data.     

Adsorption of uranium ions from aqueous solution by amine-group functionalized magnetic Fe3O4 nanoparticle

The magnetic Fe₃O₄ nanoparticle was functionalized by covalently grafting amine group with (3-aminopropyl) trimethoxy silane, and the Fe₃O₄–NH₂ nanoparticle and the Fe₃O₄ nanoparticle were characterized by Fourier transform infrared, and X-ray diffraction. And the results indicated the amine-group was immobilized successfully on the surface of Fe₃O₄. The adsorption behavior of uranium from aqueous solution by the Fe₃O₄ nanoparticle and the Fe₃O₄–NH₂ nanoparticle was investigated using batch experiments. The pH of initial aqueous solution at 5.0 and 6.0 were in favour of adsorption of uranium, and the adsorption percentage of uranium by the Fe₃O₄ nanoparticle and the Fe₃O₄–NH₂ nanoparticle were 81.2 and 95.6 %, respectively. In addition, the adsorption of uranium ions could be well-described by the Langmuir, Freundlich isotherms and pseudo-second kinetic models. The monolayer adsorption maximum capacity of the Fe₃O₄ nanoparticle and the Fe₃O₄–NH₂ nanoparticle were 85.35 and 268.49 mg/g at 298.15 K, respectively, which indicate the adsorption capacity the Fe₃O₄ nanoparticle was improved by amine functionalization.     

Extraction kinetics of Uranium(VI) and Thorium(IV) with Tri-iso-amyl phosphate from nitric acid using a Lewis Cell

The extraction kinetics of uranium(VI) and thorium(IV) with Tri-iso-amyl phosphate (TiAP) from nitric acid medium has been investigated using a Lewis Cell. Especially, dependences of the extraction rate on stirring speed, temperature, interfacial area were firstly measured to elucidate the extraction kinetics regimes. The experimental results demonstrated that extraction kinetic of U(VI) is governed by chemical reactions at interface with an activation energy, E_a, of 43.41 kJ/mol, while the rate of Th(IV) extraction is proved to be intermediate controlled, of which the E_a is 23.20 kJ/mol. Reaction orders with respect to the influencing parameters of the extraction rate are determined, and the rate equations of U(VI) and Th(IV) at 293 K have been proposed as $$ {\text{r}} = - {\text{dcUO}}_{ 2} \left( {{\text{NO}}_{ 3} } \right)_{ 2} /{\text{dt}} = 1. 80 \times 10^{ - 3} \left[ {{\text{UO}}_{ 2} \left( {{\text{NO}}_{ 3} } \right)_{ 2} } \right]^{ 1.0 1} \left[ {\text{TiAP}} \right]^{0. 5 5} , $$ $$ {\text{r}} = - {\text{dcTh }}\left( {{\text{NO}}_{ 3} } \right)_{ 4} /{\text{dt}} = 1. 8 8\times 10^{ - 3} \left[ {{\text{Th }}\left( {{\text{NO}}_{ 3} } \right)_{ 4} } \right]^{ 1.0 4} \left[ {\text{TiAP}} \right]^{ 1. 7 7} \left[ {{\text{HNO}}_{ 3} } \right]^{0. 3 8} , $$ respectively.     

The sequestration of U(VI) on functional β-cyclodextrin-attapulgite nanorods

Eight elastomeric composites (NRU, GR1–GR4, NRBG08–NRBG24) containing mixtures of different proportions of heavy metal additives (Bi, W, Gd and Sb) have been synthesized and examined as protective shields. The NRU sample was a pure rubber matrix and served as a reference sample for heavy metal modified composites. Experimental procedure used for evaluation of the composite shields and their attenuation properties was based on the utilization of HPGe spectrometry and analysis of X-ray fluorescence radiation intensity of the heavy metal additives in the following energy ranges for: Sb (20–35 keV), Gd (35–55 keV), W (55–70 keV) and Bi (70–90 keV). The main contributor to the induced X-ray fluorescence radiation within the shield is Bi additive and the intensity of the X-ray radiation generated within the energy range of 70–90 keV strongly depends on its concentration. It was found that decreasing concentration of the Bi fraction from 0.35 (GR samples) to 0.15 (NRBG samples) results in significant lowering Bi X-ray fluorescence radiation within the 70–90 keV energy range. Secondary effect of decreasing Bi concentration was efficient diminishing excitation processes for lower Z heavy metal additives (W, Gd and Sb, GR vs. NRBG samples). As the final quality parameter of the shielding properties for the examined elastomers, dose reduction factor (DRF) coefficients were calculated for each shield. It was found, that the best shielding properties are observed for composites with lower Bi concentration (0.15 vs. 0.35 Bi mass fraction) with only slight further improvement of their parameters (DRF) with increasing of Gd concentration (Gd mass fraction 0.08, 0.16 and 0.24). The most efficient dose reduction composite was found to be NRBG24 elastomer with DRF value 0.47 (53 % dose reduction) for ca. 2 mm and 0.44 g/cm² layer thickness.