Critical role of next-nearest-neighbor interlayer interaction in magnetic behavior of magnetic/nonmagnetic multilayers

We report magnetoresistance data in magnetic semiconductor multilayers, which exhibit a clear step-wise behavior as a function of external field. We attribute this highly non-trivial step-wise behavior to next-nearest-neighbor interlayer exchange coupling. Our microscopic calculation suggests that this next-nearest-neighbor coupling can be as large as 24% of the nearest-neighbor coupling. It is argued that such unusually long-range interaction is made possible by the quasi-one-dimensional nature of the system and by the long Fermi wavelength characteristic of magnetic semiconductors

A Two-Dimensional Manipulation Method for a Magnetic Microrobot with a Large Region of Interest Using a Triad of Electromagnetic Coils

This paper proposes an effective method to manipulate the 2D motions of a magnetic small-scale robot (microrobot) within a relatively large working area using a triad of electromagnetic coils (TEC). The TEC is a combination of three identical circular coils placed at the vertices of an equilateral triangle. Since it is geometrically compact and requires only three control variables (input currents), the TEC can be effectively used to generate various magnetic fields that can be used to maneuver various functional microrobots. In this paper, we established several equations to calculate the input currents of the TEC required to move a microrobot along a designated pathway effectively and precisely. We also constructed an experimental setup to demonstrate and validate the controlled motions of the microrobot using the proposed method. The results showed that the proposed method can effectively improve the TEC’s practical working area (region of interest) for manipulating the microrobot, which can possibly be applied to biomedical and biological applications, including minimally invasive surgery, targeted drug and cargo delivery, microfluidic control, etc

A Two-Dimensional Manipulation Method for a Magnetic Microrobot with a Large Region of Interest Using a Triad of Electromagnetic Coils

This paper proposes an effective method to manipulate the 2D motions of a magnetic small-scale robot (microrobot) within a relatively large working area using a triad of electromagnetic coils (TEC). The TEC is a combination of three identical circular coils placed at the vertices of an equilateral triangle. Since it is geometrically compact and requires only three control variables (input currents), the TEC can be effectively used to generate various magnetic fields that can be used to maneuver various functional microrobots. In this paper, we established several equations to calculate the input currents of the TEC required to move a microrobot along a designated pathway effectively and precisely. We also constructed an experimental setup to demonstrate and validate the controlled motions of the microrobot using the proposed method. The results showed that the proposed method can effectively improve the TEC’s practical working area (region of interest) for manipulating the microrobot, which can possibly be applied to biomedical and biological applications, including minimally invasive surgery, targeted drug and cargo delivery, microfluidic control, etc

Cynanchum wilfordii Ameliorates Testosterone-Induced Benign Prostatic Hyperplasia by Regulating 5α-Reductase and Androgen Receptor Activities in a Rat Model

Benign prostatic hyperplasia (BPH) is characterized by uncontrolled proliferation of the prostate gland. Cynanchum wilfordii has been reported to improve sexual behavior in male rats. In this study, we investigated the protective effect of an aqueous extract of C. wilfordii (CWW) against BPH development in a testosterone-induced BPH rat model. The rats were divided into the following six groups: sham/vehicle; BPH/vehicle; BPH/finasteride; and three CWW doses (50, 100, and 200 mg/kg). After a 4-week treatment with CWW, the rats were euthanized at scheduled times, and their prostates were weighed, followed by a histopathological examination. Prostate growth inhibition rates in rats administered CWW 50, 100, and 200 mg/kg were 54.5%, 51.8%, and 50.1%, respectively. The BPH/CWW group showed decreased serum testosterone and dihydrotestosterone (DHT) levels compared to the BPH/vehicle group. Furthermore, the BPH/CWW group showed reduced prostate testosterone and DHT levels compared to the BPH/vehicle group. Mechanistically, the reverse transcription-polymerase chain reaction revealed downregulated mRNA expression levels of the androgen receptor, 5α-reductase, and B-cell lymphoma-2 (Bcl-2) in the BPH/CWW200 group compared with those in the testosterone-induced groups. In conclusion, these findings show the effectiveness of CWW in slowing the progression of testosterone-induced BPH in rats

Magnetic anisotropy of crystalline Fe films grown on (001) GaAs substrates using Ge buffer layers

Magnetic anisotropy of Fe films grown on (001) GaAs substrates using Ge buffer layers were investigated by planar Hall effect measurements. In addition to phenomena arising from dominant cubic symmetry of the Fe specimen, the study of angular dependence of magnetization reversal revealed breaking of this symmetry in the form of systematic asymmetric shifts of magnetic hysteresis loops around the <110 > crystallographic directions. We ascribe such symmetry breaking to an admixture of uniaxial anisotropy associated with the [100] direction in the Fe film. To determine the parameters associated with this uniaxial anisotropy, we quantitatively analyze the asymmetric shifts of the hysteresis loop centers from the <110 > directions. Even though the value of these parameters turns out to be relatively small compared to that of the cubic anisotropy (by about two orders of magnitude), they survive up to room temperature

Molecular Discrimination of Cynanchum wilfordii and Cynanchum auriculatum by InDel Markers of Chloroplast DNA

The tuber of Cynanchum wilfordii (Baekshuoh Radix in Korean) is an important medicinal herb in Korea and China; however, it is difficult to differentiate C. wilfordii from a related medicinal herb, C. auriculatum (Baishouwu Radix in Chinese). We sought to develop a molecular method that could be used to distinguish between the tubers of C. wilfordii and C. auriculatum. We aligned the chloroplast genome sequences (available in the NCBI database) of the two species and identified three species-specific insertion and deletion (InDel) sites in the trnQ-psbK, rps2-rpoC2, and psaJ-rpl33 intergenic spacer (IGS) regions. To confirm the presence of these three InDels and validate their use as markers, we designed three primer pairs to amplify the trnQ-psbK, rps2-rpoC2, and psaJ-rpl33 IGS regions. Polymerase chain reaction (PCR) amplification of the trnQ-psbK IGS region yielded a 249 bp fragment for C. wilfordii, and 419 bp fragment for C. auriculatum, whereas the rps2-rpoC2 IGS primers produced a 629 bp fragment from C. wilfordii and a 282 bp fragment from C. auriculatum. In the psaJ-rpl33 IGS region, allele fragments of 342 and 360 bp in length were amplified from C. wilfordii, whereas 249 and 250 bp fragment were amplified from C. auriculatum. We propose these three InDel markers as a valuable, simple, and efficient tool for identifying these medicinal herbs and will thus reduce adulteration of these herbal materials in commercial markets