There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

THE large-scale use of photovoltaic devices for electricity generation is prohibitively expensive at present: generation from existing commercial devices costs about ten times more than conventional methods1. Here we describe a photovoltaic cell, created from low-to medium-purity materials through low-cost processes, which exhibits a commercially realistic energy-conversion efficiency. The device is based on a 10-µm-thick, optically transparent film of titanium dioxide particles a few nanometres in size, coated with a monolayer of a charge-transfer dye to sensitize the film for light harvesting. Because of the high surface area of the semiconductor film and the ideal spectral characteristics of the dye, the device harvests a high proportion of the incident solar energy flux (46%) and shows exceptionally high efficiencies for the conversion of incident photons to electrical current (more than 80%). The overall light-to-electric energy conversion yield is 7.1-7.9% in simulated solar light and 12% in diffuse daylight. The large current densities (greater than 12 mA cm-2) and exceptional stability (sustaining at least five million turnovers without decomposition), as well as the low cost, make practical applications feasible.

A low-cost, high-efficiency solar cell based on dye-sensitized colloidal TiO2 films

抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Titanium Dioxide Nanomaterials: Synthesis, Properties, Modifications, and Applications

This critical review shows the basis of photocatalytic water splitting and experimental points, and surveys heterogeneous photocatalyst materials for water splitting into H2 and O2, and H2 or O2 evolution from an aqueous solution containing a sacrificial reagent Many oxides consisting of metal cations with d0 and d10 configurations, metal (oxy)sulfide and metal (oxy)nitride photocatalysts have been reported, especially during the latest decade The fruitful photocatalyst library gives important information on factors affecting photocatalytic performances and design of new materials Photocatalytic water splitting and H2 evolution using abundant compounds as electron donors are expected to contribute to construction of a clean and simple system for solar hydrogen production, and a solution of global energy and environmental issues in the future (361 references)

Heterogeneous photocatalyst materials for water splitting

Principles and Applications of Semiconductor Photoelectrochemistry.

Provided are sensors, sensor arrays, and systems for detecting an analyte. A sensor provided by the disclosure comprises an amine-containing material. Such sensors are useful to detect carboxylic-containing analytes such as fatty acids.

Use of basic polymers in carbon black composite vapor detectors to obtain enhanced sensitivity and classification performance for volatile fatty acids

Ammonia (NH₃) is essential for food production and is commercially synthesized from nitrogen (N₂) and hydrogen (H₂) using the Haber–Bosch process. Enormous amounts of ammonia are made every year in a reaction that requires high temperatures and pressures, with the Haber–Bosch accounting for ∼1.6% of total annual global energy consumption. Electrocatalysts are also being explored to convert in an environmentally friendly manner N₂ to NH₃ at ambient temperature and pressure.

https://pubs.acs.org/doi/pdf/10.1021/acsenergylett.0c00496

Isotopically Selective Quantification by UPLC-MS of Aqueous Ammonia at Submicromolar Concentrations Using Dansyl Chloride Derivatization

The effects of compositionally induced changes on the semiconducting properties, optical response, chemical stability, and overall performance of KTaO_3 photoanodes in photoelectrochemical (PEC) cells have been investigated. Single crystals of n-type Ca- and Ba-doped KTaO_3 with carrier concentrations ranging from 0.45 to 11.5×10^(19) cm^(−3) were grown and characterized as photoanodes in basic aqueous electrolyte PEC cells. The PEC properties of the crystals, including the photocurrent, photovoltage, and flatband potential in contact with 8.5 M NaOH(aq) were relatively independent of whether Ca or Ba was used to produce the semiconducting form of KTaO_3. All of the Ca- or Ba-doped KTaO_3 single-crystal photoanodes were chemically stable in the electrolyte and, based on the open-circuit potential and the band-edge positions, were capable of unassisted photochemical H_2 and O_2 evolution from H_2O. The minority-carrier diffusion lengths values were small and comparable to the depletion region width. Photoanodic currents were only observed for photoanode illumination with light above the bandgap (i.e., λ<340 nm). The maximum external quantum yield occurred at λ=255 nm (4.85 eV), and the depletion width plus the minority-carrier diffusion length ranged from 20 to 65 nm for the various KTaO_3-based photoanode materials.

Growth, Characterization, and Electrochemical Properties of Doped n-Type KTaO3 Photoanodes

Transconductance measurements have been used to characterize the space-charge regions of various n-Si/liquid contacts. To perform these measurements, Si electrodes were photolithographically processed to introduce p^+-contact areas into the surface of an n-type Si electrode. The electrical conductance between these p^+ regions was then used to probe the minority carrier concentration in the near-surface region of the n-type Si. Unlike conventional differential capacitance or current-voltage measurements, these transconductance measurements can be performed under near-equilibrium conditions and can be performed in the presence of gaseous ambients or when the sample is in contact with ionically conducting electrolyte solutions. In contact with the electrolyte solutions, faradaic and solid-state conduction pathways were distinguished using ac impedance measurements. The impedance spectra provided clear evidence that contact with Me_2Fc (1,1'-dimethylferrocene)^(+/0) and Fc^(+/0) redox couples in CH_3OH(l)-1.0 M LiClO_4 formed an inversion layer in the n-Si, but that CH_3OH(l)-1.0 M LiClO_4-Me_(10)Fc^(+/0) solutions did not yield an inversion layer. These observations are consistent with prior current-voltage measurements on these junctions. The barrier heights of the n-Si/CH_3OH-Me_2Fc^(+/0) and n-Si/CH_3OH-Fc^(+/0) junctions were determined to be 1.01 and 1.02 V, respectively. These measurements provide new insight into the photoelectrochemical behavior of SI/CH_3OH contacts and provide an alternate method for characterizing the energetics of semiconductor/liquid contacts.

Measurement of barrier heights of semiconductor/liquid junctions using a transconductance method: Evidence for inversion at n-Si/CH3OH-1,1′-dimethylferrocene+/0 junctions

Nathan S. Lewis

Papers

Principles and Applications of Semiconductor Photoelectrochemistry.

Use of basic polymers in carbon black composite vapor detectors to obtain enhanced sensitivity and classification performance for volatile fatty acids

Isotopically Selective Quantification by UPLC-MS of Aqueous Ammonia at Submicromolar Concentrations Using Dansyl Chloride Derivatization

Growth, Characterization, and Electrochemical Properties of Doped n-Type KTaO3 Photoanodes

Measurement of barrier heights of semiconductor/liquid junctions using a transconductance method: Evidence for inversion at n-Si/CH3OH-1,1′-dimethylferrocene+/0 junctions