In Situ Compensation Method for Precise Integral SQUID Magnetometry of Miniscule Biological, Chemical, and Pow-der Specimens Requiring the Use of Capsules

Steadily growing interest in magnetic characterization of organic compounds for therapeutic purposes or of other irregularly shaped specimens calls for refinements of experimental methodology to satisfy experimental challenges. Encapsulation in capsules remains the method of choice, but its applicability in precise magnetometry is limited. This is particularly true for minute specimens in the single milligram range as they are outweighed by the capsules and are subject to large alignment errors. We present here a completely new experimental methodology that permits 30-fold in situ reduction of the signal of capsules by substantially restoring the symmetry of the sample holder that is otherwise broken by the presence of the capsule. In practical terms it means that the standard 30 mg capsule is seen by the magnetometer as approximately a 1 mg object, effectively opening the window for precise magnetometry of single milligram specimens. The method is shown to work down to 1.8 K and in the whole range of the magnetic fields. The method is demonstrated and validated using the reciprocal space option of MPMS-SQUID magnetometers; however, it can be easily incorporated in any magnetometer that can accommodate straw sample holders (i.e., the VSM-SQUID). Importantly, the improved sensitivity is accomplished relying only on the standard accessories and data reduction method provided by the SQUID manufacturer, eliminating the need for elaborate raw data manipulations.

In Situ Compensation Method for Precise Integral SQUID Magnetometry of Miniscule Biological, Chemical, and Powder Specimens Requiring the Use of Capsules

Steadily growing interest in magnetic characterization of organic compounds for therapeutic purposes or of other irregularly shaped specimens calls for refinements of experimental methodology to satisfy experimental challenges. Encapsulation in capsules remains the method of choice, but its applicability in precise magnetometry is limited. This is particularly true for minute specimens in the single milligram range as they are outweighed by the capsules and are subject to large alignment errors. We present here a completely new experimental methodology that permits 30-fold in situ reduction of the signal of capsules by substantially restoring the symmetry of the sample holder that is otherwise broken by the presence of the capsule. In practical terms it means that the standard 30 mg capsule is seen by the magnetometer as approximately a 1 mg object, effectively opening the window for precise magnetometry of single milligram specimens. The method is shown to work down to 1.8 K and in the whole range of the magnetic fields. The method is demonstrated and validated using the reciprocal space option of MPMS-SQUID magnetometers; however, it can be easily incorporated in any magnetometer that can accommodate straw sample holders (i.e., the VSM-SQUID). Importantly, the improved sensitivity is accomplished relying only on the standard accessories and data reduction method provided by the SQUID manufacturer, eliminating the need for elaborate raw data manipulations.

In Situ Compensation Method for Precise Integral SQUID Magnetometry of Miniscule Biological, Chemical, and Pow-der Specimens Requiring the Use of Capsules

Steadily growing interest in magnetic characterization of organic compounds aiming at therapeutic purposes, or of other irregular-shaped specimens calls for refinements of experimental methodology to satisfy experimental challenges. Encapsulation in capsules remains the method of choice, but its applicability in precise magnetometry is limited. This is particularly true for minute specimens in single mg range since they are outweighed by the capsules and due to large alignment errors. We present here a complete new experimental methodology which permits 30-fold in situ reduction of the signal of capsules. In practical terms it means that the standard 30 mg capsule is seen by the magnetometer as about 1 mg object, effectively opening the window for precise magnetometry of single mg specimens. The method is shown to work down to 1.8 K and in the whole range of the magnetic fields. The method is demonstrated and validated using the reciprocal space option of MPMS-SQUID magnetometers, however it can be easily incorporated in any magnetometer which can accommodate straw sample holders (i.e. the VSM-SQUID). Importantly, the improved sensitivity is accomplished relying only on the standard accessories and data reduction method provided by the SQUID manufacturer, eliminating needs for an elaborate raw data manipulations.

In Situ Reduction of Silver Nanoparticles on the Plasma-Induced Chitosan Grafted Polylactic Acid Nonwoven Fabrics for Improvement of Antibacterial Activity

An eco-friendly approach for improvement of antibacterial properties of polylactic acid (PLA) nonwoven fabrics was obtained by in situ reduction of silver nanoparticles (Ag NPs) on dielectric barrier discharge (DBD) plasma-induced chitosan grafted (DBD-CS-Ag NPs) PLA nonwoven fabrics. The surface morphology, surface element composition and the chemical state of silver of the PLA surfaces after the treatment were evaluated through scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), respectively. The antibacterial activity of DBD-CS-Ag NPs treated PLA against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was tested. The uniform dispersion of silver nanoparticles on the DBD-CS-Ag NPs treated PLA surface were confirmed by SEM images. The results of XPS and XRD showed that the concentration of silver element on the surface of PLA nonwoven fabrics was significantly improved after DBD-CS-Ag NPs treatment. The DBD-CS-Ag NPs treated PLA nonwoven fabrics also exhibited excellent antibacterial properties.