合成二氧化氯的催化剂和方法及该催化剂的制备

使用一种失活速率降低的催化剂用亚氯酸钠的水溶液合成二氧化氮。催化剂最好为钯,钯与其它钯系金属的混合物（如Ｐｂ＋Ｐｔ）或者是钯与第１副族金属的混合物（Ｐｂ＋Ａｕ）,所用的载体为可用第１主族金属的硕酸盐如（Ｋ２ＣＯ３）、第２主族金属的碳酸盐（如ＣａＣＯ３）或者是可转化成ＭｇＯ的镁盐改性的物质,载体还可以是第１主族金属的碳酸盐（如Ｋ２ＣＯ３）或者是可转化成ＭｇＯ的镁盐改性的物质,载体还可以是第１主族金属     

SOLAR FIBER-OPTIC MINI-DISHES: A NEW APPROACH TO THE EFFICIENT COLLECTION OF SUNLIGHT

A new concept for efficient solar energy concentration and power delivery is proposed — one that offers substantial advantages in efficiency, compactness, reduced mechanical loads, and ease of fabrication and installation relative to conventional solar designs. The design exploits the availability of low-attenuation optical fibers, as well as the practical advantages of mass producing highly accurate very small parabolic dishes. The system's building block is a miniature (e.g. 0.2 m diameter) solar dish which concentrates sunlight into a single optical fiber. The fiber transports power to a remote receiver. A second-stage concentrator can boost flux levels to those approaching the thermodynamic limit and can be performed either in each individual dish or collectively in one or more larger devices at the entrance to the remote receiver. Collector modules, close-packed with mini-dishes, are mounted on individual trackers close to the ground. Systems are modular and can be employed in central power generation ranging from a few kilowatts to tens of megawatts. Designs for maximum efficiency attaining collection efficiencies as high as 80%, and maximum-concentration designs realizing flux levels of 30 000 suns, are achievable.     

Next generation of aircraft coatings systems

The current generation of aircraft coatings had its basis in the polymer technologies of the 1970s and the use of chromate-based metal pretreatments and primers. There have been some incremental improvements in the epoxy and polyamide oligomers used in the primers as well as the isocyanates and flexible polyols used in topcoats, plus increases in the volume solids of the coatings to continue minimally meeting environmental requirements, but no truly new technologies have been developed and applied to aircraft coatings since that time. However, because of increasing economic and environmental pressures, this situation will soon change. Also, the U.S. Air Force is seeking a coating system that will have an ultimate lifetime of 30 years for maintenance cost control and fleet sustainability. The first change in the present coatings system will be in the pretreatments plus primers that currently constitute the metal protection system for the high strength Al alloys used for aircraft. For military aircraft, these alloys will continue to be Al 2024 T-3 and Al 7075-T6, heat-treated metals that have phase-separated regions rich in reactive metals such as Cu, Mg, and Zn. There are several new technologies now under consideration for such metal protection including conductive polymers as primers without Cr-based metal pretreatments, sol-gel based pretreatments and primers, plasma polymer metal pretreatments, and organo-modified aluminum oxide particles. Each of these technologies has shown some promise for Cr replacement, but each presently has a weakness that needs to be corrected for immediate usage. For the topcoat system, fluorinated polyols and improved use of UV-absorbers and light stabilizers will probably be the first changes implemented, with ceramer and other new crosslinking systems the most likely next polymer matrix candidates. The target for the entire coatings system is to have drastically improved wet-adhesion due to a covalently bonded system that has a gradient in composition that goes continuously from metal to metal oxide to mixed metal oxide/organic polymer to high-performance UV-stable organic polymer. The materials cost for such a system may be quite high, but the maintenance cost savings will much more than offset these costs. Presented at the 25th FATIPEC Congress, Sept. 19–22, 2000, in Turin, Italy. Department of Polymers & Coatings, Fargo, ND 58105.     

Uniform flux heat transfer in concentric laminar flow of two immiscible liquids

The energy equation was solved exactly for fully developed steady laminar flow in a circular pipe of two immncible Newton liquids with a concentric cylindrical interface between them, assuming invariant physical properties of the liquids, uniform heat flux at the wall and fully developed temperature profiles. It is shown that, even if the viscosity of the annular liquid is orders of magnitude smaller than that of the core liquid, the improvement in heat transfer to the core liquid by infection of the annular liquid cannot exceed a factor of 1 8     

Fully Coupled 3-D Conjugate Heat Transfer Algorithm for Borehole Heat Exchanger Performance Prediction

Quantitative three-dimensional prediction of the thermal performance of a vertical borehole heat exchanger (BHE) in a ground-source heat pump installation is sought. As BHE installation exhibits exceptionally disparate characteristic length scales, an alternative formation-fluid-thermal fully coupled algorithm is derived to quickly predict the 3-D temperature distributions. The time scale of the steady prediction is of order minutes. This simulation capability can be readily coupled to long-time (order months) unsteady simulation of an entire wellbore field. Algorithm prediction is validated by comparison with data from an instrumented commercial installation for a unique BHE conduit design, followed by illustrative design optimization or variation assessments.     

Distinctive arsenic(V) trapping modes by magnetite nanoparticles induced by different sorption processes

Arsenic sorption onto iron oxide spinels such as magnetite may contribute to arsenic immobilization at redox fronts in soils, sediments, and aquifers, as well as in putative remediation and water treatment technologies. We have investigated As(V) speciation resulting from different sorption processes on magnetite nanoparticles, including both adsorption and precipitation, using X-ray absorption fine structure (XAFS) spectroscopy and transmission electron microscopy (TEM). XAFS results suggest that AsO(4) tetrahedra form predominantly inner-sphere bidentate corner-sharing ((2)C) complexes and outer-sphere complexes on magnetite in the adsorption experiments. In the precipitation experiments, an increasing fraction of AsO(4) tetrahedra appears to be incorporated in clusters having a magnetite-like local structure with increasing As loading, the remaining fraction of As being adsorbed at the surface of magnetite particles. In the sample with the highest As loading (15.7 μmol/m(2)) XAFS data indicate that As(V) is fully incorporated in such clusters. Such processes help to explain the significantly higher arsenic uptake in precipitation samples compared to those generated in adsorption experiments. In addition, for the precipitation samples, TEM observations indicate the formation of amorphous coatings and small (~3 nm) nanoparticles associated with larger (~20-40 nm) magnetite nanoparticles, which are absent in the adsorption samples. These results suggest that As(V) could form complexes at the surfaces of the small nanoparticles and could be progressively incorporated in their structure with increasing As loading. These results provide some of the fundamental knowledge about As(V)-magnetite interactions that is essential for developing effective water treatment technologies for arsenic.     

Use of hypertonic (3%) saline/acetate infusion in the treatment of cerebral edema: Effect on intracranial pressure and lateral displacement of the brain

OBJECTIVE: To determine the effect of continuous hypertonic (3%) saline/acetate infusion on intracranial pressure (ICP) and lateral displacement of the brain in patients with cerebral edema. DESIGN: Retrospective chart review. SETTINGS: Neurocritical care unit of a university hospital. PATIENTS: Twenty-seven consecutive patients with cerebral edema (30 episodes), including patients with head trauma (n = 8), postoperative edema (n = 5), nontraumatic intracranial hemorrhage (n = 8), and cerebral infarction (n = 6). INTERVENTION: Intravenous infusion of 3% saline/acetate to increase serum sodium concentrations to 145 to 155 mmol/L. MEASUREMENTS AND MAIN RESULTS: A reduction in mean ICP within the first 12 hrs correlating with an increase in the serum sodium concentration was observed in patients with head trauma (r2 = .91, p = .03), and postoperative edema (r2 = .82, p = .06), but not in patients with nontraumatic intracranial hemorrhage or cerebral infarction. In patients with head trauma, the beneficial effect of hypertonic saline on ICP was short-lasting, and after 72 hrs of infusion, four patients required intravenous pentobarbital due to poor ICP control. Among the 21 patients who had a repeat computed tomographic scan within 72 hrs of initiating hypertonic saline, lateral displacement of the brain was reduced in patients with head trauma (2.8 +/- 1.4 to 1.1 +/- 0.9 [SEM]) and in patients with postoperative edema (3.1 +/- 1.6 to 1.1 +/- 0.7). This effect was not observed in patients with nontraumatic intracranial bleeding or cerebral infarction. The treatment was terminated in three patients due to the development of pulmonary edema, and was terminated in another three patients due to development of diabetes insipidus. CONCLUSIONS: Hypertonic saline administration as a 3% infusion appears to be a promising therapy for cerebral edema in patients with head trauma or postoperative edema. Further studies are required to determine the optimal duration of benefit and the specific patient population that is most likely to benefit from this treatment.     

Comparing the effectiveness of process-experiential with cognitive-behavioral psychotherapy in the treatment of depression.

This study compared process-experiential and cognitive-behavioral psychotherapy in the treatment of major depression in a researcher allegiance-balanced randomized clinical trial. Sixty-six clients participated in weekly sessions of psychotherapy for 16 weeks. Clients' level of depression, self-esteem, general symptom distress, and dysfunctional attitudes significantly improved in both therapy groups. Clients in both groups showed significantly lower levels of reactive and suppressive coping strategies and higher reflective coping at the end of treatment. Although outcomes were generally equivalent for the 2 treatments, there was a significantly greater decrease in clients' self-reports of their interpersonal problems in process-experiential than cognitive-behavioral therapy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Advanced Spectroscopy and APBS Modeling for Determination of the Role of His190 and Trp103 in Mouse Thymidylate Synthase Interaction with Selected dUMP Analogues

A homo-dimeric enzyme, thymidylate synthase (TS), has been a long-standing molecular target in chemotherapy. To further elucidate properties and interactions with ligands of wild-type mouse thymidylate synthase (mTS) and its two single mutants, H190A and W103G, spectroscopic and theoretical investigations have been employed. In these mutants, histidine at position 190 and tryptophan at position 103 are substituted with alanine and glycine, respectively. Several emission-based spectroscopy methods used in the paper demonstrate an especially important role for Trp 103 in TS ligands binding. In addition, the Advanced Poisson–Boltzmann Solver (APBS) results show considerable differences in the distribution of electrostatic potential around Trp 103, as compared to distributions observed for all remaining Trp residues in the mTS family of structures. Together, spectroscopic and APBS results reveal a possible interplay between Trp 103 and His190, which contributes to a reduction in enzymatic activity in the case of H190A mutation. Comparison of electrostatic potential for mTS complexes, and their mutants, with the substrate, dUMP, and inhibitors, FdUMP and N4-OH-dCMP, suggests its weaker influence on the enzyme–ligand interactions in N4OH-dCMP-mTS compared to dUMP-mTS and FdUMP-mTS complexes. This difference may be crucial for the explanation of the ”abortive reaction” inhibitory mechanism of N4OH-dCMP towards TS. In addition, based on structural analyses and the H190A mutant capacity to form a denaturation-resistant complex with N4-OH-dCMP in the mTHF-dependent reaction, His190 is apparently responsible for a strong preference of the enzyme active center for the anti rotamer of the imino inhibitor form.