Spectroscopy and Formation of Lanthanum-Hydrocarbon Radicals Formed by Association and Carbon-Carbon Bond Cleavage of Isoprene

La atom reaction with isoprene is carried out in a laser-vaporization molecular beam source. The reaction yields an adduct as the major product and C—C cleaved and dehydrogenated species as the minor ones. La(C5H8), La(C2H2), and La(C3H4) are characterized with mass-analyzed threshold ionization (MATI) spectroscopy and quantum chemical computations. The MATI spectra of all three species exhibit a strong origin band and several weak vibronic bands corresponding to La-ligand stretch and ligand-based bend excitations. La(C5H8) is a five-membered metallacycle, whereas La(C2H2) and La(C3H4) are three-membered rings. All three metallacycles prefer a doublet ground state with a La 6s1-based valence electron configuration and a singlet ion. The five-membered metallacycle is formed through La addition and isoprene isomerization, whereas the two three-membered rings are produced by La addition and insertion, hydrogen migration, and carbon-carbon bond cleavage

Lanthanum-Mediated Dehydrogenation of Butenes: Spectroscopy and Formation of La(C\u3csub\u3e4\u3c/sub\u3eH\u3csub\u3e6\u3c/sub\u3e) Isomers

La atom reactions with 1-butene, 2-butene, and isobutene are carried out in a laser-vaporization molecular beam source. The three reactions yield the same La-hydrocarbon products from the dehydrogenation and carbon-carbon bond cleavage and coupling of the butenes. The dehydrogenated species La(C4H6) is the major product, which is characterized with mass-analyzed threshold ionization (MATI) spectroscopy and quantum chemical computations. The MATI spectrum of La(C4H6) produced from the La+1-butene reaction exhibits two band systems, whereas the MATI spectra produced from the La+2-butene and isobutene reactions display only a single band system. Each of these spectra shows a strong origin band and several vibrational progressions. The two band systems from the spectrum of the 1-butene reaction are assigned to the ionization of two isomers: La[C(CH2)3] (Iso A) and La(CH2CHCHCH2) (Iso B), and the single band system from the spectra of the 2-butene and isobutene reactions is attributed to Iso B and Iso A, respectively. The ground electronic states are 2A1 (C3v) for Iso A and 2A′ (Cs) for Iso B. The ionization of the doublet state of each isomer removes a La 6s-based electron and leads to the 1A1 ion of Iso A and the 1A′ ion of Iso B. The formation of both isomers consists of La addition to the C=C double bond, La insertion into two C(sp3)—H bonds, and H2 elimination. In addition to these steps, the formation of Iso A from the La+1-butene reaction may involve the isomerization of 1-butene to isobutene prior to the C—H bond activation, whereas the formation of Iso B from the La+trans-2-butene reaction may include the trans- to cis-butene isomerization after the C—H bond activation

Lanthanum-Mediated Dehydrogenation of 1- and 2-Butynes: Spectroscopy and Formation of La(C\u3csub\u3e4\u3c/sub\u3eH\u3csub\u3e4\u3c/sub\u3e) Isomers

La atom reactions with 1-butyne and 2-butyne are carried out in a laser-vaporization molecular beam source. Both reactions yield the same La-hydrocarbon products from the dehydrogenation and carbon-carbon bond cleavage and coupling of the butynes. The dehydrogenated species La(C4H4) is characterized with mass-analyzed threshold ionization (MATI) spectroscopy and quantum chemical computations. The MATI spectra of La(C4H4) produced from the two reactions exhibit two identical transitions, each consisting of a strong origin band and several vibrational intervals. The two transitions are assigned to the ionization of two isomers: La(η4–CH2CCCH2) (Iso A) and La(η4–CH2CHCCH) (Iso B). The ground electronic states are 2A1 (C2v) for Iso A and 2A (C1) for Iso B. The ionization of the doublet state of each isomer removes a La 6s-based electron and results in a 1A1 ion of Iso A and a 1A ion of Iso B. The formation of Iso A from 2-butyne and Iso B from 1-butyne involves the addition of La to the C≡C triple bond, the activation of two C(sp3)–H bonds, and concerted elimination of a H2 molecule. The formation of Iso A from 1-butyne and Iso B from 2-butyne involves the isomerization of the two butynes to 1,2-butadiene in addition to the concerted H2 elimination

Spectroscopy and Formation of Lanthanum-Hydrocarbon Radicals Formed by C—H and C—C Bond Activation of 1-Pentene and 2-Pentene

La atom reactions with 1-pentene and 2-pentene are carried out in a laser-vaporization molecular beam source. The two reactions yield the same metal-hydrocarbon products from the dehydrogenation and carbon–carbon bond cleavage of the pentene molecules. The dehydrogenated species La(C5H8) is the major product, whereas the carbon–carbon bond cleaved species La(C2H2) and La(C3H4) are the minor ones. La(C10H18) is also observed and is presumably formed by La(C5H8) addition to a second pentene molecule. La(C5H8) and La(C2H2) are characterized with mass-analyzed threshold ionization (MATI) spectroscopy and quantum chemical computations. The MATI spectra of each species from the two reactions exhibit the same transitions. Adiabatic ionization energies and metal-ligand stretching frequencies are determined for the two species, and additional methyl bending and torsional frequencies are measured for the larger one. Five possible isomers are considered for La(C5H8), and a C1 metallacyclopentene (Iso A) is identified as the most possible isomer. La(C2H2) is confirmed to be a C2v metallacyclopropene. The ground electronic state of each species is a doublet with a La 6s1-based electron configuration, and ionization yields a singlet state. The formation of the lanthanacyclopentene includes La addition to the C=C double bond, La insertion into two C(sp3)—H bonds, and concerted dehydrogenation. For the 2-pentene reaction, the formation of the five-membered ring may also involve 2-pentene to 1-pentene isomerization. In addition to the metal addition and insertion, the formation of the three-membered metallacycle from 1-pentene includes C(sp3)—C(sp3) bond breakage and hydrogen migration from La to C(sp3), whereas its formation from 2-pentene may involve the ligand isomerization

Model-free adaptive nonlinear control of the absorption refrigeration system

This work is supported by the National Natural Science Foundation of China (Grant Nos. 61773282, 61873181, and 61922062).Peer reviewedPostprin

Effect and safety of shengxuening (extract from excrement of bombyxin) for renal anemia: a systematic review

OBJECTIVETo assess the effect and safety of Shengxuening (SXN), extract from excrement of bombyxin, in the treatment of renal anemia, compared to ferrous succinate and ferrous sulfate.METHODSAccording to the participant, intervention, comparison, outcomes, study design (PICOS) principles, we searched the Chinese Biomedical Literature Database, China National Knowledge Infrastructure Database, Chinese Evidence-Based Medicine Database, Wanfang Database (From establishment to December 2014). Two reviewers selected articles independently according to the inclusion and exclusion criteria. The quality of included studies was assessed by using the Cochrane Handbook. All statistical analyses were conducted by using Revman (vision 5.2) software.RESULTSA total of 14 randomized controlled trials (RCTs) were enrolled in the review. The results revealed that, when compared with blank group, SXN significantly improved the hemoglobin (HB) levels [MD = 6.29, 95% CI (1.65–10.94), P < 0.0008] and albumin (ALB) [MD = 10.98, 95% CI (6.97–14.99), P < 0.00001]. In addition, SXN could significantly increase the HB levels [MD = 10.98, 95% CI (6.97, 14.99), P < 0.00001]. Compared with other oral medicine SXN could improve the HB levels effectively [MD = 8.49, 95% CI (2.40, 14.58), P = 0.006]. And the subgroups analysis shown that compared with ferrous-sulfate there were significant differences [MD = 17.4, 95% CI (15.06, 19.73), P < 0.000 01] and the result of ferrous-succinate had significant differences [MD = 5.34, 95% CI (2.12, 8.56), P = 0.001] too. Compared with Intravenous iron groups, there were statistical differences [MD = −5.04, 95% CI (−9.59, −0.50), P = 0.03]. In the safety analysis, the rate of adverse reactions in SXN groups and control groups were 19.3% and 3.7%, respectively (P < 0.000 01). Due to our studies were of poor methodological quality, and the sample size were small, the results were influenced by bias.CONCLUSIONSOur findings suggest that the SXN had better effect and was safer in the treatment of RA than ferrous succinate and ferrous sulfate

Mass-Analyzed Threshold Ionization Spectroscopy of Lanthanum-Hydrocarbon Radicals Formed by C—H Bond Activation of Propene

La(C3H4) and La(C3H6) are observed from the reaction of laser-vaporized La atoms with propene by photoionization time-of-flight mass spectrometry and characterized by mass-analyzed threshold ionization spectroscopy. Two isomers of La(C3H4) are identified as methyl-lanthanacyclopropene [La(CHCCH3)] (Cs) and lanthanacyclobutene [La(CHCHCH2)] (C1); La(C3H6) is determined to be H—La(η3-allyl) (Cs), a C—H bond inserted species. All three metal-hydrocarbon radicals prefer a doublet ground state with a La 6s-based electron configuration. Ionization of the neutral doublet state of each of these radicals produces a singlet ion state by removing the La-based 6s electron. The threshold ionization allows accurate measurements of the adiabatic ionization energy of the neutral doublet state and metal-ligand and ligand-based vibrational frequencies of the neutral and ionic states. The formation of the three radicals is investigated by density functional theory computations. The inserted species is formed by La inserting into an allylic C—H bond and lanthanacyclopropene by concerted vinylic H2 elimination, whereas lanthanacyclobutene involves both allylic and vinylic dehydrogenations. The inserted species is identified as an intermediate for the formation of lanthanacyclobutene

Analysis and prediction of marine heatwaves in the Western North Pacific and Chinese coastal region

Over the past decade, marine heatwaves (MHWs) research has been conducted in almost all of the world’s oceans, and their catastrophic effects on the marine environment have gradually been recognized. Using the second version of the Optimal Interpolated Sea Surface Temperature analysis data (OISSTV2) from 1982 to 2014, this study analyzes six MHWs characteristics in the Western North Pacific and Chinese Coastal region (WNPCC, 100°E ∼ 180°E, 0° ∼ 65°N). MHWs occur in most WNPCC areas, with an average frequency, duration, days, cumulative intensity, maximum intensity, and mean intensity of 1.95 ± 0.21 times/year, 11.38 ± 1.97 days, 22.06 ± 3.84 days, 18.06 ± 7.67 °Cdays, 1.84 ± 0.50°C, and 1.49 ± 0.42 °C, respectively, in the historical period (1982 ~ 2014). Comparing the historical simulation results of 19 models of the Coupled Model Intercomparison Project Phase 6 (CMIP6) with the OISSTV2 observations, five best-performing models (GFDL-CM4, GFDL-ESM4, AWI-CM-1-1-MR, EC-Earth3-Veg, and EC-Earth3) are selected for MHWs projection (2015 ~ 2100). The MHWs characteristics projections from these five models are analyzed in detail under the Shared Socio-economic Pathway (SSP) 1-2.6, 2-4.5 and 5-8.5 scenarios. The projected MHWs characteristics under SSP5-8.5 are more considerable than those under SSP1-2.6 and 2-4.5, except for the MHWs frequency. The MHWs cumulative intensity is 96.36 ± 56.30, 175.44 ± 92.62, and 385.22 ± 168.00 °Cdays under SSP1-2.6, 2-4.5 and 5-8.5 scenarios, respectively. This suggests that different emission scenarios have a crucial impact on MHW variations. Each MHWs characteristic has an obvious increasing trend except for the annual occurrences. The increase rate of MHWs cumulative intensity for these three scenarios is 1.02 ± 0.83, 3.83 ± 1.43, and 6.70 ± 2.61 °Cdays/year, respectively. The MHWs occurrence area in summer is slightly smaller than in winter, but the MHWs average intensity is stronger in summer than in winter

Spectroscopy and Formation of Lanthanum-Hydrocarbon Radicals Formed by C—C Bond Cleavage and Coupling of Propene

La reaction with propene is carried out in a laser-vaporization molecular beam source. Three La-hydrocarbon radicals are characterized by mass-analyzed threshold ionization (MATI) spectroscopy. One of these radicals is methylenelanthanum [La(CH2)] (Cs), a Schrock-type metal carbene. The other two are a five-membered 1-lanthanacyclopent-3-en [La(CH2CHCHCH2)] (Cs) and a tetrahedron-like trimethylenemethanelanthanum [La(C(CH2)3)] (C3v). Adiabatic ionization energies and metal-ligand stretching and hydrocarbon-based bending frequencies of these species are measured from the MATI spectra, preferred structures and electronic states are identified by comparing the experimental measurements and spectral simulations, and reaction pathways for the formation of the metal-hydrocarbon radicals are investigated with density functional theory calculations. All three radicals prefer doublet ground electronic states with La 6s1-based valence electron configurations, and singly charged cations favor singlet states generated by the removal of the La 6s1 electron. The metal-carbene radical is formed via multi-step carbon-carbon cleavage involving metallacyclization, β-hydrogen migration, and metal insertion. The metal-carbene radical formed in the primary reaction reacts with a second propene molecule to form the five-membered-ring and tetrahedron-like isomers through distinct carbon-carbon coupling paths

Remodeling of the periodontal ligament and alveolar bone during axial tooth movement in mice with type 1 diabetes

ObjectivesTo observe the elongation of the axial tooth movement in the unopposed rodent molar model with type 1 diabetes mellitus and explore the pathological changes of periodontal ligament and alveolar bone, and their correlation with tooth axial movement.MethodsThe 80 C57BL/6J mice were randomly divided into the streptozotocin(STZ)-injected group (n = 50) and the control group (n = 30). Mice in the streptozotocin(STZ)-injected group were injected intraperitoneal with streptozotocin (STZ), and mice in the control group were given intraperitoneal injection of equal doses of sodium citrate buffer. Thirty mice were randomly selected from the successful models as the T1DM group. The right maxillary molar teeth of mice were extracted under anesthesia, and allowed mandibular molars to super-erupt. Mice were sacrificed at 0, 3, 6,9, and 12 days. Tooth elongation and bone mineral density (BMD) were evaluated by micro-CT analysis(0,and 12 days mice). Conventional HE staining, Masson staining and TRAP staining were used to observe the changes in periodontal tissue(0, 3, 6, 9, and 12 days mice). The expression differences of SPARC, FGF9, BMP4, NOGGIN, and type I collagen were analyzed by RT-qPCR.ResultsAfter 12 days of tooth extraction, our data showed significant super-eruption of mandibular mouse molars of the two groups. The amount of molar super-eruption in the T1DM group was 0.055mm( ± 0.014mm), and in the control group was 0.157( ± 0.017mm). The elongation of the T1DM mice was less than that of the control mice(P&lt;0.001). It was observed that the osteoclasts and BMD increased gradually in both groups over time. Compared with the control group, the collagen arrangement was more disordered, the number of osteoclasts was higher (P&lt;0.05), and the increase of bone mineral density was lower(2.180 ± 0.007g/cm3 vs. 2.204 ± 0.006g/cm3, P&lt;0.001) in the T1DM group. The relative expression of SPARC, FGF9, BMP4, and type I collagen in the two groups increased with the extension of tooth extraction time while NOGGIN decreased. The relative expression of all of SPARC, FGF9, BMP4, and type I collagen in the T1DM group were significantly lower, and the expression of NOGGIN was higher than that in the control group (P&lt;0.05).ConclusionThe axial tooth movement was inhibited in type 1 diabetic mice. The result may be associated with the changes of periodontal ligament osteoclastogenic effects and alveolar bone remodeling regulated by the extracellular matrix and osteogenesis-related factors