Conspectus A clear correlation between electronic structure and CO2 selectivity for steam reforming of methanol (SRM) was obtained with PdZn, PtZn, NiZn, and PdCd intermetallics on the basis of ...experiments and calculations. In order to rule out the effects of oxide supports, the intermetallic powders were simply prepared by alloying in an arc furnace followed by crushing in a mortar. PdZn and PdCd exhibit valence electronic densities of states similar to that of Cu and significant chemical shifts (larger than 1 eV) of Pd 3d states with respect to pure Pd, as verified by high-resolution hard X-ray photoelectron spectroscopy (HXPS) measurements and density functional theory (DFT) calculations. Consequently, they show the similar high selectivity of CO2 for the SRM reaction. However, this is not the case for PtZn and NiZn because of the slight differences in their valence electronic structures from that of PdZn. The interval between the Fermi level and the top of the d band is closely related to the selectivity of CO2 for the SRM: the larger the interval is, the higher is the selectivity of CO2. According to DFT calculations for bulk PdZn performed by Chen et al. ( Phys. Rev. B 2003, 68, 075417 ), the (111) and (100) surfaces exposing Zn and Pd in an equimolar ratio are more stable than the (001) or (110) surfaces terminated by alternative Zn or Pd layers. First-principles slab calculations for PdZn, PtZn, and NiZn show that bond breaking on the surface leads to a reduction in the d bandwidth but that the d band for stable (111) or (100) surfaces remains essentially unchanged from that of the bulk. It is intriguing that PdZn and PdCd do not contain Cu but show similar valence electronic structure and catalytic selectivity, and hence, a concept is proposed where PdZn and PdCd are regarded as pseudoelements of Cu. The basis of this concept is like electronic structure, like catalysis, which has been demonstrated by experiments and calculations. This is a logical way to enable us to look for new catalysts in which precious metals are partially or completely replaced by base metals. We do not expect that this concept can be applied to all catalytic reactions, but this approach is one of most promising ways to derive a better understanding of the origin of catalytic mechanisms and eventually allow us to design useful catalysts intentionally in the future. This Account reviews the authors’ published works on this topic.
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•CO2/CO selectivity of methanol steam reforming process is investigated.•Using DFT catalytic reactions on NiZn, PdZn and PtZn surfaces are studied.•Atomistic scenarios for reactions ...determining selectivity are constructed.•Decisive factors for selectivity of the catalysts are identified.•Possibilities how to improve CO2 selectivity are presented.
This work is focused on better understanding of the origin of CO2/CO selectivity of methanol steam reforming (MSR) catalyzed by three isostructural (L10-type) intermetallic compounds NiZn, PdZn, and PtZn. Following earlier suggestions we assume that the selectivity of MSR arises from the competition between two possible transformations of the reaction intermediate formaldehyde: the reaction of formaldehyde with hydroxyl leading ultimately to the formation of CO2, and the direct dehydrogenation of formaldehyde leading to the production of CO. We have investigated whether the differences in the activation energies for these steps explain the experimentally observed trends in selectivity. Using density-functional theory detailed atomistic scenarios for both reactions have been developed. As in vacuum the reaction of formaldehyde with hydroxyl is non-activated, it does not need the support of a catalyst to proceed. There is a clear correlation between high CO2 selectivities and weak adsorption energies of formaldehyde. On the L10(111) surfaces we have to consider the existence of four inequivalent adsorption sites, caused by the monoclinic shift of subsurface atomic planes resulting from tetragonal deformation of the L10 structure. At PtZn(111) this shift could explain the observed mixed CO2/CO selectivity of the PtZn catalyst. The proposed mechanism of selectivity can qualitatively explain the experimentally observed selectivities of the investigated intermetallic compounds. Our results can contribute also to understanding the influence of the ZnO support and the Zn-enriched PdZn surface on the selectivity of the MSR process. The possibilities how to improve the CO2 selectivity of the catalyst are also presented.
Objective
To validate a revision of the Mini Nutritional Assessment short-form (MNA®-SF) against the full MNA, a standard tool for nutritional evaluation.
Methods
A literature search identified ...studies that used the MNA for nutritional screening in geriatric patients. The contacted authors submitted original datasets that were merged into a single database. Various combinations of the questions on the current MNA-SF were tested using this database through combination analysis and ROC based derivation of classification thresholds.
Results
Twenty-seven datasets (n=6257 participants) were initially processed from which twelve were used in the current analysis on a sample of 2032 study participants (mean age 82.3y) with complete information on all MNA items. The original MNA-SF was a combination of six questions from the full MNA. A revised MNA-SF included calf circumference (CC) substituted for BMI performed equally well. A revised three-category scoring classification for this revised MNA-SF, using BMI and/or CC, had good sensitivity compared to the full MNA.
Conclusion
The newly revised MNA-SF is a valid nutritional screening tool applicable to geriatric health care professionals with the option of using CC when BMI cannot be calculated. This revised MNA-SF increases the applicability of this rapid screening tool in clinical practice through the inclusion of a “malnourished” category.
The sigma-1 receptor (Sig-1R) chaperone at the endoplasmic reticulum (ER) plays important roles in cellular regulation. Here we found a new function of Sig-1R, in that it translocates from the ER to ...the nuclear envelope (NE) to recruit chromatin-remodeling molecules and regulate the gene transcription thereof. Sig-1Rs mainly reside at the ER-mitochondrion interface. However, on stimulation by agonists such as cocaine, Sig-1Rs translocate from ER to the NE, where Sig-1Rs bind NE protein emerin and recruit chromatin-remodeling molecules, including lamin A/C, barrier-to-autointegration factor (BAF), and histone deacetylase (HDAC), to form a complex with the gene repressor specific protein 3 (Sp3). Knockdown of Sig-1Rs attenuates the complex formation. Cocaine was found to suppress the gene expression of monoamine oxidase B (MAOB) in the brain of wild-type but not Sig-1R knockout mouse. A single dose of cocaine (20 mg/kg) in rats suppresses the level of MAOB at nuclear accumbens without affecting the level of dopamine transporter. Daily injections of cocaine in rats caused behavioral sensitization. Withdrawal from cocaine in cocaine-sensitized rats induced an apparent time-dependent rebound of the MAOB protein level to about 200% over control on day 14 after withdrawal. Treatment of cocaine-withdrawn rats with the MAOB inhibitor deprenyl completely alleviated the behavioral sensitization to cocaine. Our results demonstrate a role of Sig-1R in transcriptional regulation and suggest cocaine may work through this newly discovered genomic action to achieve its addictive action. Results also suggest the MAOB inhibitor deprenyl as a therapeutic agent to block certain actions of cocaine during withdrawal.
To estimate per-person and aggregate direct medical costs of overweight and obesity and to examine the effect of study design factors. PubMed (1968-2009), EconLit (1969-2009) and Business Source ...Premier (1995-2009) were searched for original studies. Results were standardized to compute the incremental cost per overweight person and per obese person, and to compute the national aggregate cost. A total of 33 US studies met review criteria. Among the four highest-quality studies, the 2008 per-person direct medical cost of overweight was $266 and of obesity was $1723. The aggregate national cost of overweight and obesity combined was $113.9 billion. Study design factors that affected cost estimates included use of national samples vs. more selected populations, age groups examined, inclusion of all medical costs vs. obesity-related costs only, and body mass index cut-offs for defining overweight and obesity. Depending on the source of total national healthcare expenditures used, the direct medical cost of overweight and obesity combined is approximately 5.0% to 10% of US healthcare spending. Future studies should include nationally representative samples, evaluate adults of all ages, report all medical costs and use standard body mass index cut-offs.
Abstract Understanding how galaxies quench their star formation is crucial for studies of galaxy evolution. Quenching is related to a decrease of cold gas. In the first paper we showed that the dust ...removal timescale in early-type galaxies (ETGs) is about 2.5 Gyr. Here we present carbon monoxide and 21 cm hydrogen line observations of these galaxies and measure the timescale of removal of the cold interstellar medium (ISM). We find that all the cold ISM components (dust and molecular and atomic gas) decline at similar rates. This allows us to rule out a wide range of potential ISM-removal mechanisms (including starburst-driven outflows, astration, or a decline in the number of asymptotic giant branch stars), and artificial effects like the stellar mass–age correlation, environmental influence, mergers, and selection bias, leaving ionization by evolved low-mass stars and ionization/outflows by Type Ia supernovae or active galactic nuclei as viable mechanisms. We also provide evidence for an internal origin of the detected ISMs. Moreover, we find that the quenching of star formation in these galaxies cannot be explained by a reduction in the gas amount alone, because the star formation rates (SFRs) decrease faster (on a timescale of about 1.8 Gyr) than the amount of cold gas. Furthermore, the star formation efficiency (SFE) of the ETGs ( SFE ≡ SFR / M H 2 ) is lower than that of star-forming galaxies, whereas their gas mass fractions ( f H 2 ≡ M H 2 / M * ) are normal. This may be explained by the stabilization of gas against fragmentation, for example due to morphological quenching, turbulence, or magnetic fields.
Background
The long‐term survival benefits of neoadjuvant chemotherapy (NAC) and chemoradiotherapy (NACR) for oesophageal carcinoma are well established. Both are burdened, however, by toxicity that ...could contribute to perioperative morbidity and mortality.
Methods
MEDLINE, the Cochrane Library and Embase were searched to capture the incidence of any postoperative complications, cardiac complications, respiratory complications, anastomotic leakage, postoperative 30‐day mortality, total postoperative mortality and treatment‐related mortality in randomized clinical trials comparing NAC or NACR with surgery alone, or NAC versus NACR. Meta‐analyses comparing NAC and NACR were conducted by using adjusted indirect comparison.
Results
Twenty‐three relevant studies were identified. Comparing NAC or NACR with surgery alone, there was no increase in morbidity or mortality attributable to neoadjuvant therapy. Subgroup analysis of NACR for squamous cell carcinoma (SCC) suggested an increased risk of total postoperative mortality and treatment‐related mortality compared with surgery alone: risk ratio 1·95 (95 per cent confidence interval 1·06 to 3·60; P = 0·032) and 1·97 (1·07 to 3·64; P = 0·030) respectively. A combination of direct comparison and adjusted indirect comparison showed no difference between NACR and NAC regarding morbidity or mortality.
Conclusion
Neither NAC nor NACR for oesophageal carcinoma increases the risk of postoperative morbidity or perioperative mortality compared with surgery alone. There was no clear difference between NAC and NACR. Care should be taken with NACR in oesophageal SCC, where an increased risk of postoperative mortality and treatment‐related mortality was apparent.
Neither approach increases surgical risk
Background/Aims: Herbal materials derived from Juniperus communis (JCo) possess anticancer activity. In this study, we evaluated the efficacy of a JCo berry extract in suppressing glioblastoma ...growth. Methods: The effects of JCo extract on the viability of normal and glioma cell lines was analyzed using a modified 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The synergistic therapeutic effect of JCo extract and temozolomide (TMZ) on glioma cells was examined by MTT analysis. Flow cytometry analysis, the terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) test, and western blotting were performed to identify the apoptotic pathway. To determine the in vivo efficacy of the JCo extract, rats were injected with 5 × 104 rat glioma RG2 cells in the back skin and brain hemisphere and then received a subcutaneous injection in the back skin that contained either JCo extract or vehicle. Finally, blood and histologic examinations were performed to evaluate JCo toxicity. Results: The IC50 values of JCo extract were 57–69 µg/mL and 49–67 µg/mL in the glioblastoma cell lines after 24 and 48 h, respectively. However, in non-tumor cell lines, the respective IC50 values of JCo extract were 76–105 µg/mL and 77–108 µg/mL. The JCo extract had a stronger cytotoxicity and a larger range of IC50 values in glioma than in normal cells as compared to those effects caused by temozolomide (TMZ). In addition, the results of flow cytometry analysis, TUNEL test, and western blotting revealed that the JCo extract induced glioma cell cycle arrest through intrinsic and extrinsic apoptotic pathways. In the in vivo studies, a significant reduction of tumor size in JCo-treated rats, as measured by animal MRI, demonstrated that the JCo extract effectively inhibited glioma cell growth and successfully penetrated the blood-brain barrier. The immunohistochemical (IHC) staining detected positive signals of PCNA, VEGFR-1, and VEGFR -2 in 44.49%, 5.88%, and 5.85% of JCo-treated glioma cells, respectively. However, positive signals of PCNA, VEGFR-1, and VEGFR-2 were detected in 73.08%, 9.67%, and 11.70% of vehicle-treated glioma cells, respectively. The IHC examination of PCNA and VEGFR-1 and -2 indicated that JCo extract significantly decreased the degree of neovascularization. However, no significant differences in serum levels of blood cell count and hepatic enzymes, renal function index, and the histologic appearance of vital organs were detected between the JCo and vehicle-treated rats. Conclusion: The JCo extract penetrated the blood-brain barrier and significantly induced glioma cell apoptosis by reducing neovascularization via suppression of the PI3K/AKT/mTOR pathway. Furthermore, JCo extract was less cytotoxic to non-neoplastic vital organs than TMZ.
When a low-viscosity fluid penetrates a fluid of higher viscosity confined by parallel plates, finger-like patterns propagate at the interface between the two fluids. Al-housseiny et al now show that ...tapering the fluid cell can suppress this instability--providing interfacial control via a simple change in geometry.
Context.
An important aspect of quenching star formation is the removal of the cold interstellar medium (ISM; non-ionised gas and dust) from a galaxy. In addition, dust grains can be destroyed in a ...hot or turbulent medium. The adopted timescale of dust removal usually relies on uncertain theoretical estimates. It is tricky to track dust removal because the dust is constantly being replenished by consecutive generations of stars.
Aims.
Our objective is to carry out an observational measurement of the timescale of dust removal.
Methods.
We explored an approach to select galaxies that demonstrate detectable amounts of dust and cold ISM coupled with a low current dust production rate. Any decrease of the dust and gas content as a function of the age of such galaxies must, therefore, be attributed to processes governing ISM removal. We used a sample of the galaxies detected by
Herschel
in the far-infrared with visually assigned early-type morphology or spirals with red colours. We also obtained JCMT/SCUBA-2 observations for five of these galaxies.
Results.
We discovered an exponential decline of the dust-to-stellar mass ratio with age, which we interpret as an evolutionary trend for the dust removal of these galaxies. For the first time, we have directly measured the dust removal timescale for such galaxies, with a result of
τ
= (2.5 ± 0.4) Gyr (the corresponding half-life time is (1.75 ± 0.25) Gyr). This quantity may be applied to models in which it must be assumed a priori and cannot be derived.
Conclusions.
Any process which removes dust in these galaxies, such as dust grain destruction, cannot happen on shorter timescales. The timescale is comparable to the quenching timescales found in simulations for galaxies with similar stellar masses. The dust is likely of internal, not external origin. It was either formed in the past directly by supernovae (SNe) or from seeds produced by SNe, and with grain growth in the ISM contributing substantially to the dust mass accumulation.
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