Articles you may be interested inPhotoreflectance and contactless electroreflectance measurements of semiconductor structures by using bright and dark configurations Rev. Sci. Instrum. 80, 096103 (2009); 10.1063/1.3213613 Interference effects in electromodulation spectroscopy applied to GaAs-based structures: A comparison of photoreflectance and contactless electroreflectance Determination of built-in field by applying fast Fourier transform to the photoreflectance of surface-intrinsic n +type doped GaAs Appl. Phys. Lett. 74, 475 (1999); 10.1063/1.123040 Micro-electroreflectance and photoreflectance characterization of the bias dependence of the quantum confined Stark effect in a fabricated 0.98 μm InGaAs/GaAs/InGaP laser Appl.Photoreflectance ͑PR͒ of surface-intrinsic-n ϩ (s-i-n ϩ ) type doped GaAs has been simulated by electroreflectance ͑ER͒. The simulated spectra of the s-i-n ϩ sample have exhibited many Franz-Keldysh oscillations, which enable the electric field ͑F͒ to be determined. It is known that F's determined from PR are subjected to photovoltaic effect and the measured F is close to F bi Ϫ␦F/2 when the modulating field, ␦FӶF bi , where F bi is the built-in field of the sample and ␦F is the modulating field. In this work, we have investigated the relation between the measured F and ␦F not only for the region where ␦FӶF bi holds, but also for a whole range of ␦F. In order to determine the magnitude of ␦F, we have used ER to simulate PR, that is, the measurements of ER under a forward bias, which is set to be equal to ␦F/2.

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This paper describes a new analytical method, using a combination of ammonium pyrrolidine dithiocarbamate/methyl isobutyl ketone (APDC-MIBK) microextraction and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), for the determination of the concentrations of Cd and Pb in aqueous samples. Only 200 µL of organic solvent was used throughout the entire analysis process, with enhancement factors as high as 25. Recoveries from replicate analyses of natural water [NIST 1640(a)] containing mean concentrations of 3.1 mg Cd L -1 and 9.3 mg Pb L -1 were 95 ± 3 and 104 ± 4%, respectively. The corresponding detection limits were 0.6 mg L -1 for Cd and 0.9 mg L -1 for Pb. The main advantage of this approach is its simplicity in terms of sample preparation, as demonstrated by quantifying the levels of Cd and Pd in real samples, including tap water, groundwater, and seawater, using a standard addition method.

Lipid nanoparticles (LNPs) have been commonly used as a vehicle for nucleic acids, such as small interfering RNA (siRNA); the surface modification of LNPs is one of the determinants of their delivery efficiency especially in systemic administration. However, the applications of siRNA‐encapsulated LNPs are limited due to a lack effective systems to deliver to solid tumors. Here, we report a smart surface modification using a charge‐switchable ethylenediamine‐based polycarboxybetaine for enhancing tumor accumulation via interaction with anionic tumorous tissue constituents due to selective switching to cationic charge in response to cancerous acidic pH. Our polycarboxybetaine‐modified LNP could enhance cellular uptake in cancerous pH, resulting in facilitated endosomal escape and gene knockdown efficiency. After systemic administration, the polycarboxybetaine‐modified LNP accomplished high tumor accumulation in SKOV3‐luc and CT 26 subcutaneous tumor models. The siPLK‐1‐encapsulated LNP thereby accomplished significant tumor growth inhibition. This study demonstrates a promising potential of the pH‐responsive polycarboxybetaine as a material for modifying the surface of LNPs for efficient nucleic acid delivery.