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The hydrogenolysis of lignin model compounds (MCs) into high-value chemicals has received increasing attention, but their catalytic reaction mechanisms are not yet very clear. Here, we report the reaction mechanisms of the hydrogenolysis of MC into 4-acetylanisole (AAL) and guaiacol (GAL) catalyzed by LRuCl 3 (L = 4'-(4-methoxyphenyl)-2,2':6',2″-terpyridine) with MC, H 2 , and 1-phenylethan-1-ol (PEO) as the H-sources in aqueous solution with the Bro̷nsted base (NaOH), at the M06/def2-TZVP, 6-311++G (d,p) theoretical level, namely, RS-Self, RS-H 2 , and RS-PEO, respectively. After dissociation in NaOH aqueous solution, the LRuCl 3 compound can form a stable complex LRh (OH) 3 as the initial catalytically active species. Their rate-determining steps are related to the cleavage of the -C α O-H bond in both RS-Self-and RS-PEO, whereas it is associated with the heterolysis of the H-H bond in RS-H 2 . From NaOH aqueous solution, the OH - ligand of LRh(OH) 3 promotes the cleavage of the -C α O-H bond with MC and PEO as H-sources, whereas it advances the heterolysis of the H-H bond with H 2 as the H-source, owing to its strong Bro̷nsted basicity. Furthermore, the Rh center of LRh(OH) 3 mediates the cleavage of the -C α -H bond, because of its Lewis acidity. The reaction activity lowers as RS-Self > RS-PEO ≫ RS-H 2 , which is positively dependent on the protonation degree of the departing H atom. Compounds containing both -C α O-H and -C α -H groups can act as effective donors for H-sources. In the meantime, the stronger the electron-withdrawing groups they contain, the more pronounced the protonation of the -C α O-H group and the higher the reaction activity in providing H-sources. The present results provide insights into utilizing lignin's own functional groups as a hydrogen source for high-value conversion.

Ru/NC shows a good catalytic performance in cellobiose-to-sorbitol hydrogenation. However, the molecular origins of the selective orientation of the reaction pathway remain unclear. Here, we rationally designed the Ru 2 /NC catalyst, for which Ru2@N8 V4 is preferred as the model. The hydrogenation mechanisms for the hydrogenation of β-cellobiose to sorbitol employing H 2 as the H-source in aqueous solution have been investigated over Ru2@N8 V4 at the GGA-PBE/DNP level. For the hydrogenation of β-cellobiose to sorbitol, the optimal reaction pathway involves the ring-opening of cellobiose with H 2 O as a promoter and then the hydroreduction of aldehyde group, followed by the β-1,4-glycosidic bond hydrolysis. The selective orientation of the optimal reaction pathway originates from the dissociation of H 2 O on Ru-sites of Ru2@N8 V4 to form Brønsted acid (Ru-H + ) and Brønsted base (Ru-OH - ), which collaboratively promote the ring-opening. The rate-determining steps are relative to the β-1,4-glycosidic bond cleavage, where an applicable π-π interaction between reactant molecule and Ru2@N8 V4 is of critical importance. Kinetically, the β-1,4-glycosidic bond cleavage from cellubitol is more favorable than that from β-cellobiose. For the hydrogenation of β-cellobiose to cellubitol, the first ring-opening with H 2 O as promoter and then hydrogenation are kinetically superior to the direct hydrogenation and ring opening. This derives from its dissociation over Ru-sites to Ru-H and Ru-OH groups. Predictably, protic solvents (HOR) are readily dissociated into Ru-H and Ru-OR at Ru-sites, which can promote the ring-opening of pyran-ring. The present research outcomes should contribute to the theoretical understanding necessary for the development of novel supported noble metal N-doped carbon catalysts for the hydrogenation of cellulose.

Aim: To evaluate the clinical effect of a new surgery technique (covering corneal stromal lenticule, CSL) for macular hole (MH) in pathological myopia., Methods: This was a prospective non-randomized series case study. Fourteen eyes of 14 patients whose axial length were more than 29 mm and suffered from MH and macular hole retinal detachment (MHRD) were included in this study. All cases were treated with 25-gauge pars plana vitrectomy (PPV) with internal limiting membrane (ILM) peeling, covering CSL and C 3 F 8 gas tamponade. These cases were followed for 6mo, and the best-corrected visual acuity (BCVA), healing status of MH, the reattached rate of retinal detachment (RD), and reoperation rate were analyzed., Results: All cases were successfully performed the surgery and the postoperative follow-up was completed. After surgery, MHs were healed in all 14 eyes (100%, 14/14) after assessed by optical coherence tomography. The reattachment of retina was achieved in all 6 eyes (100%, 6/6) with MHRD. BCVA was improved in 12 eyes (85.71%, 12/14), and had no significant change in 2 eyes (14.29%, 2/14). The overall mean BCVA was improved from 1.80±0.77 to 0.82±0.46 logMAR ( F =10.46, P <0.01). No serious complications occurred in all cases., Conclusion: The new surgery technique (covering CSL) has high reattached rate of RD and high healing rate of MH in pathological myopia in the preliminary study. And it can effectively improve the visual function of patients. This new technique offers meaningful new ideas for treating refractory MH in pathological myopia., Competing Interests: Conflicts of Interest: Tang ZY, None; Qiao G, None; Zhang XJ, None; Xie LJ, None; Zou QX, None; He CM, None; Zhao L, None; Yang HQ, None; Quan Y, None; Cao K, None; Jiang H, None; He YK, None., (International Journal of Ophthalmology Press.)

For the conversion of fructose/methylglucoside (MG) into both methyl formate (MF) and methyl levulinate (MLev), the C-source of formate [HCOO] - remains unclear at the molecular level. Herein, reaction mechanisms catalyzed by [CH 3 OH 2 ] + in a methanol solution were theoretically investigated at the PBE0/6-311++G(d,p) level. For the conversion of fructose into MF and MLev, the formate [HCOO] - comes from the C1-atom of fructose, in which the rate-determining step lies in the reaction of 5-hydroxymethylfurfural (HMF) with CH 3 OH to yield MF and MLev. The reaction of fructose with CH 3 OH kinetically tends to generate HMF intermediates rather than yield (MF + MLev). When MG is dissolved in a methanol solution, its O2, O3, and O4 atoms are closer to the first layer of the solvent than O1, O5, and O6 atoms. For the dehydration of MG with methanol into MF and MLev, the formate [HCOO] - stems from the dominant C1- and secondary C3-atoms of MG. Kinetically, MG is ready to yield (MF + MLev), whereas fructose can induce the reaction to remain at the HMF intermediate, inhibiting the further conversion of HMF with CH 3 OH into MF and MLev. If MG isomerizes into fructose, the reaction will be more preferable for yielding HMF rather than (MF + MLev).

A Ru-containing complex shows good catalytic performance toward the hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) with the assistance of organic base ligands (OBLs) and CO 2 . Herein, we report the competitive mechanisms for the hydrogenation of LA to GVL, 4-oxopentanal (OT), and 2-methyltetrahydro-2,5-furandiol (MFD) with HCOOH or H 2 as the H source catalyzed by RuCl 3 in aqueous solution at the M06/def2-TZVP, 6-311++G(d,p) theoretical level. Kinetically, the hydrodehydration of LA to GVL is predominant, with OT and MFD as side products. With HCOOH as the H source, initially, the OBL (triethylamine, pyridine, or triphenylphosphine) is responsible for capturing H + from HCOOH, leading to HCOO - and [HL] + . Next, the Ru 3+ site is in charge of sieving H - from HCOO - , yielding [RuH] 2+ hydride and CO 2 . Alternatively, with H 2 as the H source, the OBL stimulates the heterolysis of H-H bond with the aid of Ru 3+ active species, producing [RuH] 2+ and [HL] + . Toward the [RuH] 2+ formation, H 2 as the H source exhibits higher activity than HCOOH as the H source in the presence of an OBL. Thereafter, H - in [RuH] 2+ gets transferred to the unsaturated C site of ketone carbonyl in LA. Afterwards, the Ru 3+ active species is capable of cleaving the C-OH bond in 4-hydroxyvaleric acid, yielding [RuOH] 2+ hydroxide and GVL. Subsequently, CO 2 promotes Ru-OH bond cleavage in [RuOH] 2+ , forming HCO 3 - and regenerating the Ru 3+ -active species owing to its Lewis acidity. Lastly, between the resultant HCO 3 - and [HL] + , a neutralization reaction occurs, generating H 2 O, CO 2 , and OBLs. Thus, the present study provides insights into the promotive roles of additives such as CO 2 and OBLs in Ru-catalyzed hydrogenation.

Al-containing catalysts, e.g., Al(OTf) 3 , show good catalytic performance toward the conversion of cellulose to fructose in methanol solution. Here, we report the catalytic isomerization and alcoholysis mechanisms for the conversion of cellobiose to fructose at the PBE0/6-311++G(d,p), aug-cc-pVTZ theoretical level, combining the relevant experimental verifications of electrospray ionization mass spectrometry (ESI-MS), high-performance liquid chromatography (HPLC), and the attenuated total reflection-infrared (ATR-IR) spectra. From the alcoholysis of Al(OTf) 3 in methanol solution, the catalytically active species involves both the [CH 3 OH 2 ] + Brønsted acid and the [Al(CH 3 O)(OTf)(CH 3 OH) 4 ] + Lewis acid. There are two reaction pathways, i.e., one through glucose (glycosidic bond cleavage followed by isomerization, w-G ) and another through cellobiulose (isomerization followed by glycosidic bond cleavage, w-L ). The Lewis acid ([Al(CH 3 O)(OTf)(CH 3 OH) 4 ] + ) is responsible for the aldose-ketose tautomerization, while the Brønsted acid ([CH 3 OH 2 ] + ) is in charge of ring-opening, ring-closure, and glycosidic bond cleavage. For both w-G and w-L , the rate-determining steps are related to the intramolecular [1,2]-H shift between C1-C2 for the aldose-ketose tautomerization catalyzed by the [Al(CH 3 O)(OTf)(CH 3 OH) 4 ] + species. The Lewis acid ([Al(CH 3 O)(OTf)(CH 3 OH) 4 ] + ) exhibits higher catalytic activity toward the aldose-ketose tautomerization of glycosyl-chain-glucose to glycosyl-chain-fructose than that of chain-glucose to chain-fructose. Besides, the Brønsted acid ([CH 3 OH 2 ] + ) shows higher catalytic activity toward the glycosidic bond cleavage of cellobiulose than that of cellobiose. Kinetically, the w-L pathway is predominant, whereas the w-G pathway is minor. The theoretically proposed mechanism has been experimentally testified. These insights may advance on the novel design of the catalytic system toward the conversion of cellulose to fructose.

In a solution of sorbitol (SBT) and Ga(OTf) 3 compounds, the coordination of sorbitol (SBT) to [Ga(OTf) n ] 3- n ( n = 0-3) has been investigated, using both ESI-MS spectra and density functional theory (DFT) calculations at the M06/6-311++g(d,p), aug-cc-pvtz level using a polarized continuum model (PCM-SMD). In sorbitol solution, the most stable conformer of sorbitol includes three intramolecular H-bonds, i.e. , O2H⋯O4, O4H⋯O6, and O5H⋯O3. Through ESI-MS spectra, in a tetrahydrofuran solution of both SBT and Ga(OTf) 3 compounds, five main species are observed, i.e. , [Ga(SBT)] 3+ , [Ga(OTf)] 2+ , [Ga(SBT) 2 ] 3+ , [Ga(OTf)(SBT)] 2+ , and [Ga(OTf)(SBT) 2 ] 2+ . Through DFT calculations, in a solution of sorbitol (SBT) and Ga(OTf) 3 compounds, the Ga 3+ cation tends to form five six-coordination complexes, i.e. , [Ga(η2O,O-OTf) 3 ], [Ga(η3O2-O4-SBT) 2 ] 3+ , [(η2O,O-OTf)Ga(η4O2-O5-SBT)] 2+ , [(η1O-OTf)(η2O2,O4-SBT)Ga(η3O3-O5-SBT)] 2+ , and [(η1O-OTf)(η2O,O-OTf)Ga(η3O3-O5-SBT)] + , which are in good agreement with the experimental observation of the ESI-MS spectra. For both [Ga(OTf) n ] 3- n ( n = 1-3) and [Ga(SBT) m ] 3+ ( m = 1, 2) complexes, the negative charge transfer from ligands to the Ga 3+ -center plays an important role in their stability, because of the strong polarization of the Ga 3+ cation. For [Ga(OTf) n (SBT) m ] 3- n ( n = 1, 2; m = 1, 2) complexes, the negative charge transfer from ligands to the Ga 3+ -center plays an essential role in their stability, accompanied by an electrostatic interaction between the Ga 3+ -center and ligands and/or spatial inclusion of ligands toward the Ga 3+ -center.

Objective: To investigate the clinical effect of NRD assisted Ilizarov technique in the treatment of infected bone and soft tissue defect of tibia., Methods: All 48 patients with infected bone and soft tissue defect of tibia were randomly divided into study group and control group from March 2013 to December 2020. There were 34 males and 14 females, aged from 24 to 55 years old with an average of (40.54±11.64) years old. There were 25 patients in the study group, including 17 males and 8 females, aged from 31 to 55 years old with an average of (41.36±9.69) years old. The study group were treated with NRD assisted with Ilizarov bone transport technique. There were 23 patients in control group, including 17 males and 6 females, aged from 24 to 53 years old with an average of(38.61±8.76) years old. The control group were treated with traditional bone transport technique. The curative rate, recurrence rate, incidence rate of pin track infection, time of using antibiotics, time of wound healing, time of carrying external fixation, time of bone transport, time of bone healing and postoperative function were used to evaluate the therapeutic effect of the two groups., Results: The follow-up period was from 12 to 62 months with an average of (33.0±7.2) months. At the final follow-up, there was no significant difference in the curative rate between the two groups ( P >0.05). The recurrence rate in the study group was lower than that in the control group( P <0.05). The incidence of pin track infection in the study group was lower than that in the control group ( P <0.05). The time of using antibiotics and wound healing in the study group was shorter than that in the control group( P <0.05). There was no significant difference in the time of bone transport and carrying of external fixation between the two groups( P >0.05). There was no significant difference in bone healing and postoperative function between the two groups( P >0.05)., Conclusion: NRD assisted Ilizarov technique can achieve satisfactory results in the treatment of infected bone and soft tissue defect of tibia and shorten the treatment period and the time of using antibiotics. It is worthy of development in clinic.

Chimeric antigen receptor T (CAR-T) cell therapy is an effective treatment for relapsed and refractory acute lymphoblastic leukemia (R/R ALL). However, autologous CAR-T cells derived from patients with B-ALL often show poor amplification ability, exhaustion, and anergy. To overcome these limitations, allogeneic CAR-T cells may be used as effective substitutes; however, which source would be the best substitute is unclear. In this study, we compared the immunophenotype and antitumor efficacy of anti-CD19 CAR-T cells derived from healthy donor cord blood (CB), healthy donor peripheral blood (PB), and PB of B-ALL patients [PB (patient)] in vitro and NOD-Prkdcem26cd52Il2rgem26Cd22/Nju (NCG)-immunodeficient mice, respectively. The results revealed that CAR-T cells derived from healthy donor CB and PB showed a higher proportion of naive T cells and longer tumor suppression in tumor-bearing mice than those of PB (patient). PB (patient) CAR-T cells had a higher proportion of regulatory T cells (Treg cells) and released high levels of interluekin-10 (IL-10), which also suggest a poor prognosis. Thus, CAR-T cells derived from healthy donors have better antitumor efficacy than CAR-T cells derived from PB (patient), and CB may be a good source of allogeneic CAR-T cells., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Liu, Hong, Qiu, Li, Liu, Zhu, Lai, Chen, Yang, Xu and Fang.)

A W 4 C 2 cluster was used to model a W 2 C catalyst with the armchair model of activated carbon support, noted as W 4 C 2 /AC. Over W 4 C 2 /AC, the mechanism for the hydrogenation of both -H 2 OH and -CHO groups in 5-hydroxymethylfurfural (HMF) was theoretically studied in tetrahydrofuran at GGA-PBE/DNP level. 5-Methylfurfural was the major product from only hydrodehydration of the -CH 2 OH group, whereas 2,5-dihydroxymethylfuran was the minor product from the hydrogenation of both -CH 2 OH and -CHO groups. The rate-determining steps were concerned with the -C(H) 2 -H bond formation for the hydrodehydration of -CH 2 OH group, and the -(OH)(H)-H bond formation for the hydrogenation of -CHO group. Kinetically, W-sites promoted the hydrodehydration of -CH 2 OH group and inhibited the hydrogenation of -CHO group. This stemmed from the strong Lewis acidity of W-sites, which easily accepted the lone-pair electrons of the oxygen atom in the -C(OH)(H)- group, making -C(OH)(H)-H bond formation hard, and hampering the hydrogenation of the -CHO group., (© 2022 Wiley-VCH GmbH.)

Aim: To evaluate the therapeutic effect of amniotic membrane (AM) for covering high myopic macular hole associated with retinal detachment following failed primary surgery., Methods: Seventeen eyes of 17 patients whose axial length was more than 29 mm suffered from macular hole (MH) or MH associated with retinal detachment (RD), and had previously surgery of pars plana vitrectomy (PPV) with internal limiting membrane (ILM) peeling and silicone oil (SO) tamponade. Half a year after the surgery, optical coherence tomography (OCT) showed that MH did not heal in all 17 eyes and RD was still maintained in 13 eyes of these 17 eyes. We performed SO removal combined with AM covering on macular area and C 3 F 8 tamponade, and phacoemulsification combined with intraocular lens implantation simultaneously cataract eyes. We followed up these patients for one year., Results: In all 17 eyes, SO was removed successfully, MHs were healed and RDs were reattached. One eye (5.89%, 1/17) had AM shifted half a month after surgery and underwent a second surgery to adjust the position of the AM and supplement C 3 F 8 . After surgery, the visual acuity (VA) improved in 15 eyes (88.24%, 15/17), no change in two eyes (11.76%, 2/17). No serious complications occurred in all eyes., Conclusion: AM covering is helpful to rescue the previous failure surgery of high myopic MH., (International Journal of Ophthalmology Press.)

Vanadium-containing catalysts exhibit good catalytic activity toward the aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformyfuran (DFF). The aerobic oxidation mechanism of HMF to DFF catalyzed by VO 2 + with counterpart anion in N , N -dimethylacetamide (DMA) solution have been theoretically investigated. In DMA solution, the stable VO 2 + -containing complex is the four-coordinated [V(O) 2 (DMA) 2 ] + species. For the gross reaction of 2HMF + O 2 → 2DFF + 2H 2 O, there are three main reaction stages, i.e. , the oxidation of the first HMF to DFF with the reduction of [V(O) 2 (DMA) 2 ] + to [V(OH) 2 (DMA)] + , the aerobic oxidation of [V(OH) 2 (DMA)] + to the peroxide [V(O) 3 (DMA)] + , and the oxidation of the second HMF to DFF with the reduction of [V(O) 3 (DMA)] + to [V(O) 2 (DMA) 2 ] + . The rate-determining reaction step is associated with the C-H bond cleavage of -CH 2 group of the first HMF molecule. The peroxide [V(O) 3 (DMA)] + species exhibits better oxidative activity than the initial [V(O) 2 (DMA) 2 ] + species, which originates from its narrower HOMO-LUMO gap. The counteranion Cl - exerts promotive effect on the aerobic oxidation of HMF to DFF catalyzed by [V(O) 2 (DMA) 2 ] + species., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The fundamental understanding of the cooperativity of a Brønsted acid together with its anion for cellulose conversion in an aqueous solution is limited at present, in which cellobiose has usually been regarded as a bridge that connects monosaccharides and cellulose. The mechanism of β-cellobiose conversion to 5-hydroxymethylfurfural (HMF) catalyzed by a Brønsted acid (H 3 O + ) accompanied by counteranions in an aqueous solution has been studied using quantum chemical calculations at the M06-2X/6-311++G(d,p) level under a polarized continuum model (PCM-SMD). For the formation of the first HMF from cellobiose, there are three reaction pathways, i.e., through cellobiulose and glycosyl-HMF (C/H), through cellobiulose and fructose (C/F/H), and through glucose (C/G/H). For these three reaction pathways, the rate-determining steps are associated with the intramolecular [1,2]-H shift in the aldose-ketose tautomerization. C/H is the thermodynamically predominant pathway, while C/G/H is the kinetically dominant pathway. From cellobiose, the origin of the first HMF results kinetically from a small proportion of both C/H and C/F/H and from a large proportion of C/G/H. For the role of the counteranion in the catalytic activity of H 3 O + , the halide anions (Cl - and Br - ) act as promoters, whereas both NO 3 - anions and carboxylate-containing anions behave as inhibitors. The roles of these anions in β-cellobiose conversion to HMF can be correlated with their electrostatic potential and atomic number, which may cause a decrease in the relative enthalpy energy and the value of entropy on interacting with the cation moiety. These insights may advance the novel design of sustainable conversion systems for cellulose conversion into HMF.

The selective removal of oxygen from 5-hydroxymethylfurfural (HMF) is challenging for the effective utilization of biomass. The catalytic mechanisms of palladium acetate toward the conversion of HMF to furfuryl alcohol (FFA), 5-methylfurfural (5-MF) and 2,5-dihydroxymethyl furan (DHMF) have been theoretically investigated. The decarbonylation of HMF to FFA includes (i) migratory extrusion, (ii) metal-acetate-co-assisted deprotonation, (iii) decarbonylation, (iv) metal-assisted deprotonation, and (v) migratory extrusion and catalyst regeneration. Both hydrogenation and deoxidation of HMF with HCOOH as the H-source involve (i) migratory extrusion, (ii) oxidative addition, (iii) reductive elimination, (iv) metal-assisted deprotonation, and (v) migratory extrusion and catalyst regeneration. The C-H bond cleavage is the crucial reaction step, in which the metal-acetate-co-assisted deprotonation is kinetically more preferable than the oxidative addition. Both FFA and DHMF are kinetically superior to 5-MF. In terms of selectivity, increasing the temperature is beneficial to decarbonylation and decreasing the temperature is advantageous to hydrogenation. The present finding provides molecular-level insight into the functions of both the metal-center and coordinated-ligand in the Pd(OAc)2 catalyst, which may drive the novel design of catalytic systems toward both decarbonylation and hydrogenation reactions.

It is unclear at the molecular level why HY (HY = RSH, or ROH, or RNH2) with HPPh2 additives kinetically affects the reaction pathway to the formation of different monomers (Ph2P-SeCd-Y or Ph2P-SeCdSe-Y) in the systhesis of semiconductor nanocrystals. In the present work, it was found that in a [Cd(OA)2 + Se[double bond, length as m-dash]P(C8H17)3 + HPPh2 + HY] mixture, HY behaves as a mediator for the formation of the initial kind of monomer, besides as a hydrogen/proton donor in the release of oleic acid and as an accelerant in the Se-P bond cleavage, which follows the mechanism of hydrogen-shift/nucleophilic-attack. The capability of the HY additive to provide a H-source decreases in the order SePPh2H > RSH > HPPh2 > ROH > RNH2, while the performance of HY to accelerate Se-P bond cleavage decreases in the order HPPh2 > RSH > RNH2 > ROH. The capacity of HY to promote the formation of the Ph2P-SeCd-Y monomer decreases in the order RSH > HPPh2 > ROH > RNH2, while the effect of HY to drive the formation of the Ph2P-SeCdSe-Y monomer decreases in the order HPPh2 > RSH > RNH2 > ROH. The activation strain energy plays a key role in both the Se-P and H-Y bond cleavage, which correlates negatively to the size of the coordinated atom radius. When only HPPh2 is present without other HY species (HY = RNH2, or RSH, or ROH), Ph2P-SeCdSe-PPh2 is preferentially formed. Alternatively, when both HY (HY = RNH2, or RSH, or ROH) and HPPh2 are present, Ph2P-SeCd-Y is favorably formed. For the formation of Ph2P-SeCd-Y (Y = -PPh2, -SR, -OR, and -NHR), SePPh2H embodies the catalytic performance, while HPPh2 serves as the catalyst for the formation of Ph2P-SeCdSe-Y (Y = -NHR or -OR). Our study brings a molecular-level insight into the relationship between the CdSe monomer and the phosphorous-containing side-product, which may advance the rational design and synthesis of quantum dots.

Little is known about the detailed structural information at the interface of Pt n cluster and γ-Al 2 O 3 (001) surface, which plays an important role in the dehydrogenation and cracking of hydrocarbons. Here, the nucleation and growth of Pt n ( n = 1-8, 13) clusters on a γ-Al 2 O 3 (001) surface have been examined using density functional theory. For the most stable configuration Pt n /γ-Al 2 O 3 (001) ( n = 1-8, 13), Pt n clusters bond to the γ-Al 2 O 3 (001) surface through Pt-O and Pt-Al bonds at the expense of electron density of the Pt n cluster. With the increase in the Pt n cluster size, both the metal-support interaction and the nucleation energies exhibit an odd-even oscillation pattern, which are lower for an even Pt n cluster size than those for its adjacent odd ones. Both the metal-surface and metal-metal interactions are competitive, which control the nanoparticle morphology transition from two-dimension (2D) to three-dimension (3D). On the γ-Al 2 O 3 (001) surface, when the metal-support interaction governs, smaller clusters such as Pt 1 , Pt 2 , Pt 3 , and Pt 4 prefer a planar 2D nature. Alternatively, when the metal-metal interaction dominates, larger clusters such as Pt 5 , Pt 6 , Pt 7 , Pt 8 , and Pt 13 exhibit a two-layer structure with one or more Pt atoms on the top layer not interacting directly with the support. Herein, the Pt 4 cluster is the most stable 2D structure; Pt 5 and Pt 6 clusters are the transition from the 2D to the 3D structure; and the Pt 7 cluster is the smallest 3D structure., Competing Interests: The authors declare no competing financial interest.

The formation mechanism of CdSe monomers from the reaction of cadmium oleate (Cd(OA)2) and SePPh2H in the presence of HPPh2 and RNH2 was studied systematically at the M06//B3LYP/6-31++G(d,p),SDD level in 1-octadecene solution. Herein, SePPh2H, HPPh2, and RNH2 act as hydrogen/proton donors with a decreased capacity, leading to the release of oleic acid (RCOOH). The longer the radius of the coordinated atom is, the larger the size of the cyclic transition state is, which lowers the activation strain and the Gibbs free energy of activation for the release of RCOOH. From the resulting RCOOCdSe-PPh2, for the formation of Ph2P-CdSe-PPh2 (G), SePPh2H acts as a catalyst, in which the turnover frequency determining transition state (TDTS) is characteristic of the Se-P bond cleavage. For the formation of RHN-CdSe-PPh2 (H), SePPh2H also serves as a catalyst, in which the TDTS is representative of the N-H bond cleavage. For the formation of Ph2PSe-CdSe-NHR (I), HPPh2 behaves as a catalyst, in which the TDTS is typical of the Se-P and N-H bond cleavage. The rate constants increase as kI < kH < kG, which is in good agreement with our previous experimental observations reported. The present study brings insight into the use of additives such as HPPh2 and RNH2 to synthesize colloidal quantum dots.

The catalytic mechanism of 2NO + 2CO → N2 + 2CO2 on Rh4 cluster has been systematically investigated on the ground and first excited states at the B3LYP/6-311+G(2d),SDD level. For the overall reaction of 2NO + 2CO → N2 + 2CO2, the main reaction pathways take place on the facet site rather than the edge site of the Rh4 cluster. The turnover frequency (TOF) determining transition states are characteristic of the second N-O bond cleavage with rate constant k4 = 1.403 × 10(11) exp (-181 203/RT) and the N-N bond formation for the intermediate N2O formation with rate constant k2 = 3.762 × 10(12) exp (-207 817/RT). The TOF-determining intermediates of (3)N(b)Rh4NO and (3)N(b)Rh4O(b)(NO) are associated with the nitrogen-atom molecular complex, which is in agreement with the experimental observation of surface nitrogen. On the facet site of Rh4 cluster, the formation of CO2 stems solely from the recombination of CO and O atom, while N2 originates partly from the recombination of two N atoms and partly from the decomposition of N2O. For the N-O bond cleavage or the synchronous N-O bond cleavage and C-O bond formation, the neutral Rh4 cluster exhibits better catalytic performance than the cationic Rh4(+) cluster. Alternatively, for N-N bond formation, the cationic Rh4(+) cluster possesses better catalytic performance than the neutral Rh4 cluster.

The coordination of cyclic β-D-glucose (CDG) to both [Al(OH)(aq)](2+) and [Al(OH)2(aq)](1+) ions has been theoretically investigated, using quantum chemical calculations at the PBE0/6-311++G(d,p), aug-cc-pvtz level under polarizable continuum model IEF-PCM, and molecular dynamics simulations. [Al(OH)(aq)](2+) ion prefers to form both six- and five-coordination complexes, and [Al(OH)2(aq)](+) ion to form four-coordination complex. The two kinds of oxygen atoms (on hydroxyl and ring) of CDG can coordinate to both [Al(OH)(aq)](2+) and [Al(OH)2(aq)](+) ions through single-O-ligand and double-O-ligand coordination, wherein there exists some negative charge transfer from the lone pair electron on 2p orbital of the coordinated oxygen atom to the empty 3s orbital of aluminum atom. The charge transfer from both the polarization and H-bond effects stabilizes the coordinated complex. When the CDG coordinates to both [Al(OH)(H2O)4](2+) and [Al(OH)2(H2O)2](1+) ions, the exchange of water with CDG would take place. The six-coordination complex [(ηO4,O6(2)-CDG)Al(OH)(H2O)3](2+) and the five-coordination complex [(ηO4,O6(2)-CDG)Al(OH)2(H2O)](1+) are predicted to be the thermodynamically most preferable, in which the polarization effect plays a crucial role. The molecular dynamics simulations testify the exchange of water with CDG, and then support a five-coordination complex [(ηO4,O6(2)-CDG)Al(OH)2(H2O)](1+) as the predominant form of the CDG coordination to [Al(OH)2(aq)](1+) ion.

The peroxo dizinc Zn(2)O(2) complex Q coordinated by imidazole and carboxylate groups for each Zn center has been designed to model the hydroxylase component of methane monooxygenase (MMO) enzyme, on the basis of the experimentally available structure information of enzyme with divalent zinc ion and the MMO with Fe(2)O(2) core. The reaction mechanism for the hydroxylation of methane and its derivatives catalyzed by Q has been investigated at the B3LYP*/cc-pVTZ, Lanl2tz level in protein solution environment. These hydroxylation reactions proceed via a radical-rebound mechanism, with the rate-determining step of the C-H bond cleavage. This radical-rebound reaction mechanism is analogous to the experimentally available MMOs with diamond Fe(2)O(2) core accompanied by a coordinate number of six for the hydroxylation of methane. The rate constants for the hydroxylation of substrates catalyzed by Q increase along CH(4) < CH(3)F < CH(3)CN ≈ CH(3)NO(2) < CH(3)CH(3). Both the activation strain ΔE(≠)(strain) and the stabilizing interaction ΔE(≠)(int) jointly affect the activation energy ΔE(≠). For the C-H cleavage of substrate CH(3)X, with the decrease of steric shielding for the substituted CH(3)X (X = F > H > CH(3) > NO(2) > CN) attacking the O center in Q, the activation strain ΔE(≠)(strain) decreases, whereas the stabilizing interaction ΔE(≠)(int) increases. It is predicted that the MMO with peroxo dizinc Zn(2)O(2) core should be a promising catalyst for the hydroxylation of methane and its derivatives.

Objective: To assess the effect of puerarin, a natural flavonoid found in Chinese Pueraria Lobata (Wild.) Ohwi, on promotion of new bone formation., Methods: Osteoblasts isolated from calvarial of newborn rats were cultured in vitro in the presence of puerarin at various concentrations. The viability of osteoblasts and alkaline phosphotase activity and mineral node formation were determined. In addition, osteoblasts seeded in the β-tricaclium phosphate scalfolds as bone substitute were implanted in rat dorsal muscles. Half -of the recipient rats received intramuscular injection of puerarin at 10 mg/(kg·d) for 7 days. Osteogenesis was analyzed by examining the histology after 4 weeks of implantation., Results: The viability of osteoblasts treated with puerarin at either 40 or 80 μmol/L was significantly higher than that of the control (P<0.05 and P<0.01, respectively). Alkaline phosphatase and mineral modules were significantly increased in osteoblasts cultured with puerarin at 40 or 80 mol/L when compared with that of the untreated cells. The puerarin-treated rats had a higher rate of bone formation in the osteoblast implants than the control rats (6.35% vs. 1.32%, respectively, P<0.05)., Conclusion: Puerarin was able to affect osteoblast proliferation and differentiation, and promote the new bone formation in osteoblast implants.

The reaction mechanism of the gas-phase Pt atom with C(3)H(8) has been systematically investigated on the singlet and triplet potential energy surfaces at CCSD(T)//BPW91/6-311++G(d, p), Lanl2dz level. Pt atom prefers the attack of primary over secondary C-H bonds in propane. For the Pt + C(3)H(8) reaction, the major and minor reaction channels lead to PtC(3)H(6) + H(2) and PtCH(2) + C(2)H(6), respectively, whereas the possibility to form products PtC(2)H(4) + CH(4) is so small that it can be neglected. The minimal energy reaction pathway for the formation of PtC(3)H(6) + H(2), involving one spin inversion, prefers to start at the triplet state and afterward proceed along the singlet state. The optimal C-C bond cleavages are assigned to C-H bond activation as the first step, followed by cleavage of a C-C bond. The C-H insertion intermediates are kinetically favored over the C-C insertion intermediates. From C-C to C-H oxidative insertion, the lowering of activation barrier is mainly caused by the more stabilizing transition state interaction ΔE(≠) (int), which is the actual interaction energy between the deformed reactants in the transition state.

The gas-phase reaction mechanism between palladium monoxide and methane has been theoretically investigated on the singlet and triplet state potential energy surfaces (PESs) at the CCSD(T)/AVTZ//B3LYP/6-311+G(2d, 2p), SDD level. The major reaction channel leads to the products PdCH(2) + H(2)O, whereas the minor channel results in the products Pd + CH(3)OH, CH(2)OPd + H(2), and PdOH + CH(3). The minimum energy reaction pathway for the formation of main products (PdCH(2) + H(2)O), involving one spin inversion, prefers to start at the triplet state PES and afterward proceed along the singlet state PES, where both CH(3)PdOH and CH(3)Pd(O)H are the critical intermediates. Furthermore, the rate-determining step is RS-CH(3) PdOH → RS-2-TS1cb → RS-CH(2)Pd(H)OH with the rate constant of k = 1.48 × 10(12) exp(-93,930/RT). For the first C-H bond cleavage, both the activation strain ΔE(≠)(strain) and the stabilizing interaction ΔE(≠)(int) affect the activation energy ΔE(≠), with ΔE(≠)(int) in favor of the direct oxidative insertion. On the other hand, in the PdCH(2) + H(2) O reaction, the main products are Pd + CH(3)OH, and CH(3)PdOH is the energetically preferred intermediate. In the CH(2)OPd + H(2) reaction, the main products are Pd + CH(3)OH with the energetically preferred intermediate H(2)PdOCH(2). In the Pd + CH(3)OH reaction, the main products are CH(2)OPd + H(2), and H(2)PdOCH(2) is the energetically predominant intermediate. The intermediates, PdCH(2), H(2) PdCO, and t-HPdCHO are energetically preferred in the PdC + H(2), PdCO + H(2), and H(2)Pd + CO reactions, respectively. Besides, PdO toward methane activation exhibits higher reaction efficiency than the atom Pd and its first-row congener NiO., (Copyright © 2011 Wiley Periodicals, Inc.)

Objective: To investigate the effects and possible mechanism of Panax Notoginseng saponins (PNS) on oxidative stress-induced damage and apoptosis in bone marrow stromal cells (BMSCs)., Methods: BMSCs were isolated and cultured from 2-month-old New Zealand rabbits by the density gradient centrifugation combined with adherent method. The third passage cells were used for subsequent experiments. Oxidative stress was induced in cultured BMSCs by H(2)O(2) (0.1 mmol/L). BMSCs were pretreated with 25-200 μg/mL PNS for 4 h before H(2)O(2) treatment. Proliferation of BMSCs was observed using MTT assay. Alkaline phosphatase (ALP) activity, as an index of early osteoblastic differentiation, was determined with an ALP assay kit. Flow cytometry was used to observe the apoptosis of BMSCs by staining with annexinV-FITC/propidium iodide. Oxidative stress level was examined by reactive oxygen species (ROS) assay. The protein expressions of Bax, Bcl-2 and Caspase-3 in BMSCs were analyzed by Western blotting., Results: PNS had different concentration-dependent effects on proliferation and osteoblast differentiation of BMSCs induced by H(2)O(2). A PNS concentration of 100 μg/mL was determined as the optimal effective concentration. PNS markedly attenuated H(2)O(2)-induced apoptosis rate from 41.91% to 14.67% (P<0.01). PNS significantly decreased ROS level induced by H(2)O(2) (P<0.01). Furthermore, pretreatment with PNS significantly reversed H(2)O(2)-induced inhibition of Bcl-2 expression and augmentation of Bax and Caspase-3 expression (P<0.01)., Conclusion: PNS had a protective effect on oxidative stress-induced damage and apoptosis in cultured rabbit BMSCs through scavenging ROS and regulating the Bcl-2/Bax pathway.

The stable tetrahedral derivative Ni(PF(3))(4) is reported to generate binuclear Ni(2)(PF(3))(n) ions in its mass spectrum emerging from ion-molecule reactions. Theoretical studies on such binuclear complexes indicate Ni(2)(PF(3))(7) to be energetically unfavorable with respect to decomposition into Ni(PF(3))(4) + Ni(PF(3))(3). However, viable rather unsymmetrical structures with two PF(3) bridges for Ni(2)(PF(3))(n) (n = 6, 5, 4) are reported here as well as a triply semibridged Ni(2)(PF(3))(5) structure. The nickel-nickel distances in these Ni(2)(PF(3))(n) derivatives suggest a formal double bond (2.51 A), a formal triple bond (2.26 A), and a formal double bond (2.34 A) for n = 6, 5, and 4, respectively. The mononuclear Ni(PF(3))(n) derivatives are predicted to have tetrahedral, trigonal planar, and bent (139 degrees ) structures for n = 4, 3, and 2, respectively.

The gas-phase reaction mechanism between methane and rhodium monoxide for the formation of methanol, syngas, formaldehyde, water, and methyl radical have been studied in detail on the doublet and quartet state potential energy surfaces at the CCSD(T)/6-311+G(2d, 2p), SDD//B3LYP/6-311+G(2d, 2p), SDD level. Over the 300-1100 K temperature range, the branching ratio for the Rh((4)F) + CH(3)OH channel is 97.5-100%, whereas the branching ratio for the D-CH(2)ORh + H(2) channel is 0.0-2.5%, and the branching ratio for the D-CH(2)ORh + H(2) channel is so small to be ruled out. The minimum energy reaction pathway for the main product methanol formation involving two spin inversions prefers to both start and terminate on the ground quartet state, where the ground doublet intermediate CH(3)RhOH is energetically preferred, and its formation rate constant over the 300-1100 K temperature range is fitted by k(CH3RhOH) = 7.03 x 10(6) exp(-69.484/RT) dm(3) mol(-1) s(-1). On the other hand, the main products shall be Rh + CH(3)OH in the reactions of RhO + CH(4), CH(2)ORh + H(2), Rh + CO +2H(2), and RhCH(2) + H(2)O, whereas the main products shall be CH(2)ORh + H(2) in the reaction of Rh + CH(3)OH. Meanwhile, the doublet intermediates H(2)RhOCH(2) and CH(3)RhOH are predicted to be energetically favored in the reactions of Rh + CH(3)OH and CH(2)ORh + H(2) and in the reaction of RhCH(2) + H(2)O, respectively., (2009 Wiley Periodicals, Inc.)

Objective: To study the treatment and therapeutic effects in the shearing-type and comminuted talar body fractures., Methods: From October 1988 to September 2005,34 patients with shearing-type or comminuted talar body fractures were followed up. There were 19 males and 15 females ranged from 13 to 55 years (averaged 28.8 years). The disease course ranged from 3 to 14 days (averaged 6.0 days). Ten patients with a displacement of no more than 3 mm were treated with plastic cast. Eighteen patients were treated with open reduction and internal fixation, 6 patients were treated with joint fusion. The assessment of clinical efforts depend on patients' ache, active range of the joint and limp., Results: The mean follow up was 5.04 years (ranged from 3 to 19 years). All the patients were healed. The clinical outcomes were evaluated according to Hawkins evaluation score in which ache, active range of the joint and limp was respectively acssessed. There were 6 patients reached an excellent result, 9 good, 11 fair and 8 poor. Fifteen patients had osteonecrosis, 18 patients had traumatic arthritis of ankle joint, and 14 patients had traumatic arthritis of subtalar joint., Conclusion: Patients whose displacement of fracture is not more than 3 mm should be treated with plastic cast. Operation and internal fixation should be performed in patients whose displacement of fracture is more than 3 mm after close reduction. Joint fusion should be performed in patients whose talar body fracture is comminuted severely and the surface of joint can not be repaired. The patients of talar body scissored fracture or comminuted fracture has bad prognosis.

The comprehensive mechanism survey on the gas-phase reaction between nickel monoxide and methane for the formation of syngas, formaldehyde, methanol, water, and methyl radical has been investigated on the triplet and singlet state potential energy surfaces at the B3LYP/6-311++G(3df, 3pd)//B3LYP/6-311+G(2d, 2p) levels. The computation reveals that the singlet intermediate HNiOCH(3) is crucial for the syngas formation, whereas two kinds of important reaction intermediates, CH(3)NiOH and HNiOCH(3), locate on the deep well, while CH(3)NiOH is more energetically favorable than HNiOCH(3) on both the triplet and singlet states. The main products shall be syngas once HNiOCH(3) is created on the singlet state, whereas the main products shall be methyl radical if CH(3)NiOH is formed on both singlet and triplet states. For the formation of syngas, the minimal energy reaction pathway (MERP) is more energetically preferable to start on the lowest excited singlet state other than on the ground triplet state. Among the MERP for the formation of syngas, the rate-determining step (RDS) is the reaction step for the singlet intermediate HNiOCH(3) formation involving an oxidative addition of NiO molecule into the C-H bond of methane, with an energy barrier of 120.3 kJ mol(-1). The syngas formation would be more effective under higher temperature and photolysis reaction condition., ((c) 2009 Wiley Periodicals, Inc.)

Objective: To explore the effects of different doses of puerarin on proliferation of cultured vascular endothelial cells in vitro., Methods: The hearts of three new-born SD rats 5 days old were mechanically minced and enzymatically digested with collagenase and trypsin, then vascular endothelial cells were counted, washed and resuspended in Dulbecco's minimum essential medium (DMEM) added with 20% heat inactivated fetal calf serum, then inoculated in 2% gelatin-coated tissue culture flasks. Vascular endothelial cells at passage 3 were used in the experiment. Except for the normal control group, the vascular endothelial cells were cultured with puerarin in various concentrations (0.01, 0.1, 1, 10 and 100 micromol/L) for 24 hours, and the morphology and the number of the cultured endothelial cells were observed. Methyl thiazolyl tetrazolium (MTT) colorimetry was used to determine the proliferation of the cultured vascular endothelial cells. Flow cytometry (FCM) were used to detect the proliferation index (PI) of the vascular endothelial cells and the expression of proliferating cell nuclear antigen (PCNA) was detected by immunohistochemical method., Results: The cell morphology was normal under the inverted microscope in each group. The number and proliferation activities of vascular endothelial cells were significantly increased by 1, 10 and 100 micromol/L puerarin compared with those of the blank control group, especially the 100 micromol/L puerarin group, and there were no remarkable changes in with 0.1 micromol/L and 0.01 micromol/L puerarin groups. The same results were seen in the positive rate of PCNA expression and PI., Conclusion: Puerarin has dose-dependent effects on the proliferation activity of vascular endothelial cells.

Objective: To study the clinical effect of tractive reduction with external fixator and arthroscopically assisted treatment for tibial plateau fractures., Methods: From February 2003 to January 2005, a total of 26 cases with tibial plateau fractures were reviewed. There were 4 cases of type I fracture, 5 type II, 4 type III, 6 type IV, 5 type V and 2 type VI based on Schatzker criteria. Before operation, X-ray examination and CT scanning were done. During operation, the dissociative fragments were reconstructed by tractive reduction with external fixator arthroscopically and fixated with screws or plates., Results: All the fractures were healed within 1.5 - 4 months, with no severe complications such as poor wound healing, infection or osteofascial compartment syndrome. All patients that were followed up for 7 - 21 months (mean, 16 months) showed no traumatic osteoarthritis, inversion or eversion of the knee. According to the Rasmussen scoring system, the outcome was excellent in 11 cases, good in 13 and fair in 2, with total score of 27 +/- 2., Conclusions: As for Schatzker type I - VI tibial plateau fractures, tractive reduction with external fixator and arthroscopically assisted treatment is characterized by minimal invasion, fast fracture healing. It broadens operative interspace of articular cavity, improves accuracy of reduction, is beneficial for knee joint function to recover.