Reversed-phase high-performance liquid chromatography (RP-HPLC) is the most popular chromatographic mode, accounting for more than 90% of all separations. HPLC itself owes its immense popularity to ...it being relatively simple and inexpensive, with the equipment being reliable and easy to operate. Due to extensive automation, it can be run virtually unattended with multiple samples at various separation conditions, even by relatively low-skilled personnel. Currently, there are >600 RP-HPLC columns available to end users for purchase, some of which exhibit very large differences in selectivity and production quality. Often, two similar RP-HPLC columns are not equally suitable for the requisite separation, and to date, there is no universal RP-HPLC column covering a variety of analytes. This forces analytical laboratories to keep a multitude of diverse columns. Therefore, column selection is a crucial segment of RP-HPLC method development, especially since sample complexity is constantly increasing. Rationally choosing an appropriate column is complicated. In addition to the differences in the primary intermolecular interactions with analytes of the dispersive (London) type, individual columns can also exhibit a unique character owing to specific polar, hydrogen bond, and electron pair donor–acceptor interactions. They can also vary depending on the type of packing, amount and type of residual silanols, “end-capping”, bonding density of ligands, and pore size, among others. Consequently, the chromatographic performance of RP-HPLC systems is often considerably altered depending on the selected column. Although a wide spectrum of knowledge is available on this important subject, there is still a lack of a comprehensive review for an objective comparison and/or selection of chromatographic columns. We aim for this review to be a comprehensive, authoritative, critical, and easily readable monograph of the most relevant publications regarding column selection and characterization in RP-HPLC covering the past four decades. Future perspectives, which involve the integration of state-of-the-art molecular simulations (molecular dynamics or Monte Carlo) with minimal experiments, aimed at nearly “experiment-free” column selection methodology, are proposed.
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IJS, KILJ, NUK, PNG, UL, UM
Realizing quantum speedup for practically relevant, computationally hard problems is a central challenge in quantum information science. Using Rydberg atom arrays with up to 289 qubits in two spatial ...dimensions, we experimentally investigate quantum algorithms for solving the Maximum Independent Set problem. We use a hardware-efficient encoding associated with Rydberg blockade, realize closed-loop optimization to test several variational algorithms, and subsequently apply them to systematically explore a class of graphs with programmable connectivity. We find the problem hardness is controlled by the solution degeneracy and number of local minima, and experimentally benchmark the quantum algorithm's performance against classical simulated annealing. On the hardest graphs, we observe a superlinear quantum speedup in finding exact solutions in the deep circuit regime and analyze its origins.
With the aid of 3D acoustic emission (AE) monitoring system, the cracking process of granite under compressive stress condition and its effect on the hydro-mechanical properties is experimentally ...studied. The granite is taken from Beishan area, a preferable region for high-level radioactive waste (HLW) disposal in China. The experiment results suggest that the rock failure and degradation of mechanical properties are essentially related to the propagation and coalescence of induced cracks. Using an anisotropic damage tensor proposed by Shao et al., the damage evolution during the whole loading process is studied according to the experimental data. It is revealed that the damage evolution is mainly initiated with the appearance of nonlinear mechanical behaviour, and accelerated close to the failure point and in post-peak region. The estimated damage variable in lateral direction is found be globally higher than the value in vertical direction. The recorded AE events indicate that cracking process of granite could be accelerated due to the existence of hydraulic pressure. As a result, much lower compressive strength is obtained under same effective confining pressure in hydro-mechanical coupling tests. A similar tendency of damage and permeability is noticed, and the permeability variation in granite is found to be negligible before the coalescence of microcracks. Finally, an empirical relation is proposed to describe the influence of damage evolution and confining pressure on permeability variation.
•The damage evolution of granite is characterized from both macro and micro point of view.•The microcracking process in compression test is studied based on the recorded AE events.•Similar variation tendency of damage and permeability during loading process is noticed.•Damage impact on permeability is found to be limited before the coalescence of microcracks.•An equation is proposed to represent the impact of damage and stress condition on permeability.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Face-centered cubic (fcc) HEAs, particularly the typical FeCoNiCrMn HEA, are promising for cryogenic applications but generally exhibit relatively low strength at ambient temperature, which limits ...their widespread uses. In this work, we present a systematic study of enhancing simultaneously the strength and ductility of FeCoNiCrMn HEAs via tailoring the phase stability and stacking fault energy (SFE). It was found that in Fe20CoxNi40-xCr20Mn20 (x = 20–30 at.%) HEAs, with the increase of Co, the SFE was gradually decreased and another hcp (hexagonal close-packed) phase was eventually formed in the alloy containing 28 at.% Co. As a result, the deformation mode changes from dislocation glide to mechanical twinning, then to γfcc → εhcp martensitic transformation. Our analysis indicates that the small critical shear stress for twinning resulted from the reduced SFE provides a steady strain hardening rate in a wide strain regime and postpones the plastic instability, eventually leading to the concurrent enhancement in the tensile strength and ductility. Our results not only shed lights on understanding of the effects of SFE on the mechanical properties, but also have important implications on the development of HEAs with a unique combination of high strength and large ductility.
•Increase of the Co content decreases the SFE and phase stability of FeCoNiCrMn alloy.•TRIP effects were achieved with the increase of Co content.•Increase of Co enhances the strength and ductility simultaneously.•Effects of the SFE on deformation mechanism were explored.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Dapsone is an important medication for the treatment of leprosy, but a life-threatening drug hypersensitivity syndrome develops in some patients. In this report from China, an
HLA-B
locus is ...identified as a strong genetic risk factor for the syndrome.
Dapsone (4-4′-sulfonyldianiline), which was first synthesized in 1908,
1
is both an antibiotic and an antiinflammatory agent. Dapsone alone or in combination with other drugs has been used for the prevention and treatment of infectious diseases (e.g., leprosy, malaria, and actinomycetoma, as well as
Pneumocystis jirovecii
pneumonia in persons with human immunodeficiency virus HIV infection) and chronic inflammatory diseases characterized by the infiltration of neutrophils or eosinophils (e.g., dermatitis herpetiformis, linear IgA dermatosis, subcorneal pustular dermatosis, and erythema elevatum diutinum).
2
,
3
About 0.5 to 3.6% of persons treated with dapsone have a drug hypersensitivity syndrome,
3
–
5
which was first described by . . .
Multiferroics, defined for those multifunctional materials in which two or more kinds of fundamental ferroicities coexist, have become one of the hottest topics of condensed matter physics and ...materials science in recent years. The coexistence of several order parameters in multiferroics brings out novel physical phenomena and offers possibilities for new device functions. The revival of research activities on multiferroics is evidenced by some novel discoveries and concepts, both experimentally and theoretically. In this review, we outline some of the progressive milestones in this stimulating field, especially for those single-phase multiferroics where magnetism and ferroelectricity coexist. First, we highlight the physical concepts of multiferroicity and the current challenges to integrate the magnetism and ferroelectricity into a single-phase system. Subsequently, we summarize various strategies used to combine the two types of order. Special attention is paid to three novel mechanisms for multiferroicity generation: (1) the ferroelectricity induced by the spin orders such as spiral and E-phase antiferromagnetic spin orders, which break the spatial inversion symmetry; (2) the ferroelectricity originating from the charge-ordered states; and (3) the ferrotoroidic system. Then, we address the elementary excitations such as electromagnons, and the application potentials of multiferroics. Finally, open questions and future research opportunities are proposed.
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BFBNIB, GIS, IJS, KISLJ, NUK, PNG, UL, UM, UPUK
Abstract
Understanding the sources of lunar water is crucial for studying the history of lunar evolution, as well as the interaction of solar wind with the Moon and other airless bodies. Recent ...orbital spectral observations revealed that the solar wind is a significant exogenous driver of lunar surficial hydration. However, the solar wind is shielded over a period of 3–5 days per month as the Moon passes through the Earth’s magnetosphere, during which a significant loss of hydration is expected. Here we report the temporal and spatial distribution of polar surficial OH/H
2
O abundance, using Chandrayaan-1 Moon Mineralogy Mapper (
M
3
) data, which covers the regions inside/outside the Earth’s magnetosphere. The data shows that polar surficial OH/H
2
O abundance increases with latitude, and that the probability of polar surficial OH/H
2
O abundance remains at the same level when in the solar wind and in the magnetosphere by controlling latitude, composition, and lunar local time. This indicates that the OH/H
2
O abundance in the polar regions may be saturated, or supplemented from other possible sources, such as Earth wind (particles from the magnetosphere, distinct from the solar wind), which may compensate for thermal diffusion losses while the Moon lies within the Earth’s magnetosphere. This work provides some clues for studies of planet–moon systems, whereby the planetary wind serves as a bridge connecting the planet with its moons.
Emission from field burning of crop residue, a common practice in many parts of the world today, has potential effects on air quality, atmosphere and climate. This study provides a comprehensive size ...and compositional characterization of particulate matter (PM) emission from rice straw (RS) burning using both
in situ experiments (11 spread field burning) and laboratory hood experiments (3 pile and 6 spread burning) that were conducted during 2003-2006 in Thailand. The carbon balance and emission ratio method was used to determine PM emission factors (EF) in the field experiments. The obtained EF varied from field to hood experiments reflecting multiple factors affecting combustion and emission. In the hood experiments, EF were found to be depending on the burning types (spread or pile), moisture content and the combustion efficiency. In addition, in the field experiments, burning rate and EF were also influenced by weather conditions, i.e. wind. Hood pile burning produced significantly higher EF (20
±
8
g
kg
−1 RS) than hood spread burning (4.7
±
2.2
g
kg
−1 RS). The majority of PM emitted from the field burning was PM
2.5 with EF of 5.1
±
0.7
g
m
−2 or 8.3
±
2.7
g
kg
−1 RS burned. The coarse PM fraction (PM
10–2.5) was mainly generated by fire attention activities and was relatively small, hence the resulting EF of PM
10 (9.4
±
3.5
g
kg
−1 RS) was not significantly higher than PM
2.5. PM size distribution was measured across 8 size ranges (from <0.4
μm to >9.0
μm). The largest fractions of PM, EC and OC were associated with PM
1.1. The most significant components in PM
2.5 and PM
10 include OC, water soluble ions and levoglucosan. Relative abundance of some methoxyphenols (e.g., acetylsyringone), PAHs (e.g., fluoranthene and pyrene), organochlorine pesticides and PCBs may also serve as additional signatures for the PM emission. Presence of these toxic compounds in PM of burning smoke increases the potential toxic effects of the emission. For illustration, an estimation of the annual RS field burning in Thailand was made using the obtained
in situ field burning EF and preliminary burning activity data.
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