铜陵、南陵地区古铜矿冶遗址炉渣的科技研究

安徽铜陵、南陵地区铜矿资源丰富，古代矿冶遗址数量众多，最早可追溯至二里头文化时期。各遗址遍地分布的炉渣、炉壁等矿冶遗物，为研究中国早期的铜矿冶炼技术提供了大量的实物资料。本工作采用X射线衍射分析（XRD）、X射线荧光分析（XRF）和扫描电镜能谱分析（SEM-EDS）等多种技术手段，对安徽铜陵、南陵地区古铜矿冶遗址的炉渣样品进行检测分析，以了解该地区早期的铜矿冶炼技术。XRD分析结果显示，所检测炉渣样品的物相以铁橄榄石、辉石、钙铁辉石为主，伴有石英、方石英、磁铁矿等矿物，符合炼铜渣的物相特征。根据炉渣的SiO₂，CaO和Fe₂O₃的含量，可将51个炉渣样品分为三大类：Ⅰ类炉渣、Ⅱ类炉渣和Ⅲ类炉渣。其中，Ⅰ类炉渣钙、硅、铁含量较高，其CaO含量远高于Ⅱ类和Ⅲ类炉渣，为铁硅钙系。相较而言，Ⅱ类炉渣为高铁系，其Fe₂O₃含量明显高于Ⅰ类和Ⅲ类炉渣；Ⅲ类炉渣为高硅系，其SiO₂含量较高，钙、铁含量较低。所有炉渣样品的铁含量均高于普通熔炼渣，结合其物相分析结果，可推测全部炉渣为冶炼渣。Ⅰ类、Ⅱ类炉渣的Ca和Fe含量呈现很强的负相关性，且波动范围很大，显示二者的含量并非人工调控，更可能是来自矿石中的天然成分。据此可以推测，本地区的早期工匠可能尚未认识到含钙和含铁助熔剂的作用，没有掌握不同类型铜矿石的配矿技术。SEM-EDS的分析结果表明，炉渣中的金属颗粒夹杂以冰铜、红铜和砷铜为主，表明该地区同时存在红铜和砷铜的冶炼活动。不同品位的冰铜颗粒大多来自不同遗址，尚没有在同一遗址发现较多品位依次升高的冰铜颗粒，因而难以确认冰铜熔炼环节的存在，不能证明上述遗址是否已采用了“硫化铜矿-冰铜-铜”的冶炼技术。所发现的冰铜颗粒，可能是采用硫化铜矿死焙烧工艺或混合矿原料冶炼的结果。铜陵夏家墩遗址炉渣中砷铜颗粒的存在，表明该地区早至西周时期，很可能已掌握了采用共熔还原法冶炼砷铜的技术。相关研究结果，对探讨砷铜技术的起源和传播，以及中国早期冶金技术的发展和生产组织状况均具有重要意义。     

Sites of Protonation and Unimolecular Fragmenta tion of Protonated N-Hydroxyphthalimide in the Gas Phase

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神舟3号飞船中分辨率成像光谱仪场地替代定标新方法研究

神舟3号飞船(SZ-3)搭载的中分辨率成像光谱仪(CMODIS)是我国下一代对地环境卫星遥感器的试验仪器,能获取地气系统30个可见光-近红外通道观测数据,这些高光谱数据应用,特别是定量遥感产品反演受到辐射定标的严重制约。文章在传统的在轨遥感器场地辐射校正基础上,提出了星地准同步观测场地辐射校正新方法,在缺少足够地面同步观测数据情况下,实现了CMODIS场地辐射校正,并达到了预期辐射校正精度要求。同时基于敦煌场地反射率光谱光滑的特点,利用EOS/MODIS大气订正后的通道反射比进行光谱内插,开展一种新的交叉定标方法试验。文章针对SZ-3/CMODIS数据,用此两种方法独立进行场地替代定标,试验结果能够相互验证,表明这两种定标方法切实可行,定标精度可靠,为我国下一代环境气象卫星传感器在轨辐射定标提供了新的定标方法和技术。     

Modulating Skeletons of Covalent Organic Framework for High-Efficiency Gold Recovery

Covalent organic frameworks (COFs) have attracted considerable attention as adsorbents for capturing and separating gold from electronic wastes. To enhance the binding capture efficiency, constructing hydrogen-bond nanotraps along the pore walls was one of the most widely adopted approaches. However, the development of absorbing skeletons was ignored due to the weak binding ability of the gold salts (Au). Herein, we demonstrated skeleton engineering to construct highly efficiently absorbs for Au capture. The strong electronic donating feature of diarylamine units enhanced the electronic density of binding sites (imine-linkage) and thus resulted in high capacities over 1750 mg g⁻¹ for all three COFs. Moreover, the absorbing performance was further improved via the ionization of diarylamine units. The ionic COF achieved 90 % of the maximal adsorption capacity, 1.63 times of that from the charge-neutral COF within ten minutes, and showed remarkable uptakes of 1834 mg g⁻¹, exceptional selectivity (97.45 %) and cycling stability. The theoretical calculation revealed the binding sites altering from imine bonds to ionic amine sites after ionization of the frameworks, which enabled to bind the AuCl₄⁻ via coulomb force and contributed to enhanced absorbing kinetics. This work inspires us to design molecular/ionic capture based on COFs.     

Parity alternation of interstellar molecules cyanopolyynes HCnN (n = 1–17)

In this paper, we report the design of models for interstellar molecules HC_nN (n = 1–17) by means of the B3LYP density functional method. We performed geometry optimization and calculation on vibrational frequency. We find that the ground-state (G-S) isomers of HC_nN (n = 1–17) are with the N atom located at one end and the H atom at the other end of a C_n chain; they are all linear except for HC₂N which is bent. When n is odd, the C_n chain is polyacetylene-like whereas when n is even, the C_n chain displays a structure that is cumulenic-like in the middle of the C_n chain. It is found that the G-S isomers of odd-n HC_nN (n = 1–17) are more stable than those of even-n ones. The finding is in accord with the relative intensities of HC_nN recorded in laboratory investigations, and in consistent with the results of objects observed in interstellar media. We provide explanations for such a trend of even/odd alternation based on concepts of the highest vibrational frequency, bonding character, electronic configuration, incremental binding energy, nucleus-independent chemical shift, and dissociation channels.     

Laser excitation spectrum of C3 in the region 26 000-30 700 cm

The vibrational structure of the electronic state of C₃ in the region 26 000-30 775 cm⁻¹ has been re-examined, using laser excitation spectra of jet-cooled molecules. Rotational constants and vibrational energies have been determined for over 60 previously-unreported vibronic levels; a number of other levels have been re-assigned. The vibrational structure is complicated by interactions between levels of the upper and lower Born-Oppenheimer components of the state, and by the effects of the double minimum potential in the Q₃ coordinate, recognized by Izuha and Yamanouchi [16]. The present work shows that there is also strong anharmonic resonance between the overtones of the ν₁ and ν₃ vibrations. For instance, the levels 2 1⁺ 1 and 0 1 ⁺ 3 are nearly degenerate in zero order, but as a result of the resonance they give rise to two levels 139 cm⁻¹ apart, centered about the expected position of the 2 1⁺ 1 level. With these irregularities recognized, every observed vibrational level up to 30 000 cm⁻¹ (a vibrational energy of over 5000 cm⁻¹) can now be assigned. A vibronic level at 30181.4 cm⁻¹, which has a much lower B′ rotational constant than nearby levels of the state, possibly represents the onset of vibronic perturbations by the electronic state; this state is so far unknown, but is predicted by the ab initio calculations of Ahmed et al. [36].     

“Expanded” local mode approach for XY2 (C2v) molecules

For XY₂ (C_2v symmetry) molecules, the local mode method is modified on the basis of a careful analysis of the transformation coefficients l_Nαλ and the properties of the intramolecular potential function, and an expanded local mode approach is derived. It is shown that relationships between known spectroscopic parameters, found in the spectroscopic literature, can be improved. New relationships between the centrifugal distortion coefficients are obtained. It is shown that knowledge of the centrifugal distortion coefficients of the ground vibrational state allows the possibility of predicting values of both the band centres and the spectroscopic parameters of deformational bands, even under conditions of a total absence of initial information on these deformational bands. The prediction possibility of the derived expanded local mode approach is analyzed.     

Theoretical studies of hydrogen storage in binary Ti-Ni,Ti-Cu,and Ti-Fe alloys

Theoretical studies have been carried out to examine hydrogen storage in some binary transition metal alloys which include titanium as one of the alloying elements. Quantum mechanical calculations at the Extended Hückel level of approximation have been performed on numerous clusters of compositions Ti₁₈Ni₁₈, Ti₁₈Ni₁₈H, Ti₁₈Ni₁₈H₁₂, Ti₂₄Ni₁₂, Ti₂₄Ni₁₂H, Ti₂₄Ni₁₂Hi₁₂, Ti₁₆Cu₁₆, Ti₁₆Cu₁₆H, Ti₂₄Cu₂, Ti₁₆Fe₁₆, Ti₁₆Fe₁₆H₉, and Ti₁₆Fe₁₆H₃₂, to yield information on energetics, densities of states, charge distributions, and the effects of hydrogenation on these properties. In addition, ab initio calculations at the split valence level of approximation have been performed on several smaller clusters. The hydrogens have been shown to acquire a partially anionic character in all cases. Another conclusion is that the preference of H for certain types of sites (for example the tetrahedral Ti₄ sites in crystalline TiCu) is more likely to be related not to the intrinsically greater stability of a hydrogen atom located in such a site, but to more general topological and electronic considerations. Qualitative concepts related to the classification, spatial distribution, and sizes and shapes of hole sites which could become occupied by hydrogen atoms, have been shown to correlate with hydrogen storage capacity for crystalline materials. These qualitative concepts have been extended to amorphous materials and corroborate the observations that under optimized conditions amorphous alloys can be found with better reversible hydrogen storage properties than the crystalline or microcrystalline systems. Distorted tetrahedral and octahedral holes have been examined in detail, and parameters (volume, area, tetrahedrality, and octahedrality) have been introduced to describe their sizes and shapes. An algorithmic surveying technique has been introduced, and shown to provide useful information about the limiting amounts of hydrogen uptake.Camille and Henry Dreyfus teacher-scholar     

Spectroscopic Signatures of Internal Hydrogen Bonds of Brønsted-Acid Sites in the Zeolite H-MFI

The location of Brønsted-acid sites (bridging OH groups, b-OH) at different crystallographic positions of zeolite catalysts influences their reactivity due to varying confinement. Selecting the most stable b-OH conformers at each of the 12 T-sites (T=Si/Al) of H-MFI, a representative set of 26 conformers is obtained which includes free b-OH groups pointing into the empty pore space and b-OH groups forming H-bonds across five- or six-membered rings of TO₄ tetrahedra. Chemically accurate coupled-cluster-quality calculations for periodic models show that the strength of internal H-bonds and, hence, the OH bond length vary substantially with the framework position. For 11 of the 19 H-bonded b-OH groups examined, our predictions fall into the full width at half maximum range of the experimental signals at 3250±175 cm⁻¹ and 7.0±1.4 ppm which supports previously debated assignments of these signals to H-bonded b-OH sites.     

Atomically Dispersed Cobalt/Copper Dual-Metal Catalysts for Synergistically Boosting Hydrogen Generation from Formic Acid

The development of practical materials for (de)hydrogenation reactions is a prerequisite for the launch of a sustainable hydrogen economy. Herein, we present the design and construction of an atomically dispersed dual-metal site Co/Cu−N−C catalyst allowing significantly improved dehydrogenation of formic acid, which is available from carbon dioxide and green hydrogen. The active catalyst centers consist of specific CoCuN₆ moieties with double-N-bridged adjacent metal-N₄ clusters decorated on a nitrogen-doped carbon support. At optimal conditions the dehydrogenation performance of the nanostructured material (mass activity 77.7 L ⋅ g_metal⁻¹ ⋅ h⁻¹) is up to 40 times higher compared to commercial 5 % Pd/C. In situ spectroscopic and kinetic isotope effect experiments indicate that Co/Cu−N−C promoted formic acid dehydrogenation follows the so-called formate pathway with the C−H dissociation of HCOO* as the rate-determining step. Theoretical calculations reveal that Cu in the CoCuN₆ moiety synergistically contributes to the adsorption of intermediate HCOO* and raises the d-band center of Co to favor HCOO* activation and thereby lower the reaction energy barrier.