Conduction Mechanism Analysis of Abrupt- and Gradual-Switching InGaZnO Memristors.

In this work, two types of InGaZnO (IGZO) memristors were fabricated to confirm the conduction mechanism and degradation characteristics of memristors with different electrode materials. The IGZO memristor exhibits abrupt switching characteristics with the Pd electrode owing to the formation and destruction of conductive filaments but shows gradual switching characteristics with the p-type Si electrode according to the amount of generated oxygen vacancy. The electrical characteristics and conduction mechanisms of the device are analyzed using an energy band diagram and experimentally verified with random telegraph noise characteristics confirming the trap effects on the device conduction.

Device modeling of two-steps oxygen anneal-based submicron InGaZnO back-end-of-line field-effect transistor enabling short-channel effects suppression.

Amorphous oxide semiconductor (AOS) field-effect transistors (FETs) have been integrated with complementary metal-oxide-semiconductor (CMOS) circuitry in the back end of line (BEOL) CMOS process; they are promising devices creating new and various functionalities. Therefore, it is urgent to understand the physics determining their scalability and establish a physics-based model for a robust device design of AOS BEOL FETs. However, the advantage emphasized to date has been mainly an ultralow leakage current of these devices. A device modeling that comprehensively optimizes the threshold voltage (VT), the short-channel effect (SCE), the subthreshold swing (SS), and the field-effect mobility (µFE) of short-channel AOS FETs has been rarely reported. In this study, the device modeling of two-steps oxygen anneal-based submicron indium-gallium-zinc-oxide (IGZO) BEOL FET enabling short-channel effects suppression is proposed and experimentally demonstrated. Both the process parameters determining the SCE and the device physics related to the SCE are elucidated through our modeling and a technology computer-aided design (TCAD) simulation. In addition, the procedure of extracting the model parameters is concretely supplied. Noticeably, the proposed device model and simulation framework reproduce all of the measured current-voltage (I-V), VT roll-off, and drain-induced barrier lowering (DIBL) characteristics according to the changes in the oxygen (O) partial pressure during the deposition of IGZO film, device structure, and channel length. Moreover, the results of an analysis based on the proposed model and the extracted parameters indicate that the SCE of submicron AOS FETs is effectively suppressed when the locally high oxygen-concentration region is used. Applying the two-step oxygen annealing to the double-gate (DG) FET can form this region, the beneficial effect of which is also proven through experimental results; the immunity to SCE is improved as the O-content controlled according to the partial O pressure during oxygen annealing increases. Furthermore, it is found that the essential factors in the device optimization are the subgap density of states (DOS), the oxygen content-dependent diffusion length of either the oxygen vacancy (VO) or O, and the separation between the top-gate edge and the source-drain contact hole. Our modeling and simulation results make it feasible to comprehensively optimize the device characteristic parameters, such as VT, SCE, SS, and µFE, of the submicron AOS BEOL FETs by independently controlling the lateral profile of the concentrations of VO and O in two-step oxygen anneal process.

Compact SPICE Model of Memristor with Barrier Modulated Considering Short- and Long-Term Memory Characteristics by IGZO Oxygen Content.

This paper introduces a compact SPICE model of a two-terminal memory with a Pd/Ti/IGZO/p+-Si structure. In this paper, short- and long-term components are systematically separated and applied in each model. Such separations are conducted by the applied bias and oxygen flow rate (OFR) during indium gallium zinc oxide (IGZO) deposition. The short- and long-term components in the potentiation and depression curves are modeled by considering the process (OFR of IGZO) and bias conditions. The compact SPICE model with the physical mechanism of SiO2 modulation is introduced, which can be useful for optimizing the specification of memristor devices.

Effect of Post-Annealing on Barrier Modulations in Pd/IGZO/SiO2/p+-Si Memristors.

In this article, we study the post-annealing effect on the synaptic characteristics in Pd/IGZO/SiO2/p+-Si memristor devices. The O-H bond in IGZO films affects the switching characteristics that can be controlled by the annealing process. We propose a switching model based on using a native oxide as the Schottky barrier. The barrier height is extracted by the conduction mechanism of thermionic emission in samples with different annealing temperatures. Additionally, the change in conductance is explained by an energy band diagram including trap models. The activation energy is obtained by the depression curve of the samples with different annealing temperatures to better understand the switching mechanism. Moreover, our results reveal that the annealing temperature and retention can affect the linearity of potentiation and depression. Finally, we investigate the effect of the annealing temperature on the recognition rate of MNIST in the proposed neural network.

High-Resolution Ultrasound-Assisted Assessment of Preliminary Short-term Safety Outcomes of an Implant-Based Augmentation Mammaplasty Using a Bioengineered, Cell-Friendly, Smooth-Surface Device in Korean Females.

BACKGROUND: The Motiva Ergonomix Round SilkSurface (Establishment Labs Holdings Inc., Alajuela, Costa Rica) is one of the representative brands of the fifth generation of a silicone gel-filled breast implant with a microtextured surface. OBJECTIVES: In this study, the authors describe preliminary short-term safety outcomes of an implant-based augmentation mammaplasty using the Motiva Ergonomix Round SilkSurface in Korean females. METHODS: The authors performed a retrospective analysis of medical records in a total of 69 females (n = 69) receiving an implant-based augmentation mammaplasty using the Motiva Ergonomix Round SilkSurface between September 26, 2017, and December 31, 2020. The authors analyzed incidences of postoperative complications. RESULTS: A total of 6 cases (8.7%) of postoperative complications occurred; these include 2 cases (2.9%) of early seroma, 1 case (1.4%) of capsular contracture, 2 cases (2.9%) of alterations in the shape, and 1 case (1.4%) of foreign body sensation. Time-to-events were estimated at 266.81 ± 273.17 days. CONCLUSIONS: The authors describe our preliminary short-term safety outcomes of an implant-based augmentation mammaplasty using the Motiva Ergonomix Round SilkSurface in Korean females. But this deserves further large-scale studies with long periods of follow-up.

Short-term treatment outcomes and safety of two representative brands of the fifth-generation silicone gel-filled breast implants in Korea.

It is allegedly reported that the BellaGel® SmoothFine (HansBiomed Co. Ltd., Seoul, Korea) and Motiva ErgonomixTM (Establishment Labs Holdings Inc., Alajuela, Costa Rica) are representative brands of a microtextured breast implant in Korea. We compared short-term safety outcomes between them. We evaluated the patients who received breast augmentation using the BellaGel® SmoothFine (n = 264) or the Motiva Ergonomix™ (n = 76) for aesthetic purposes and those with available medical records. They were followed up during a mean period of 122.11 ± 95.37 (4-477) and 126.80 ± 116.29 (13-534) days in the corresponding order. Early seroma occurred at an incidence of 1.89 and 5.26% following breast augmentation using the BellaGel® SmoothFine and the Motiva ErgonomixTM, respectively. This difference reached statistical significance (p < 0.05). Of note, CC occurred at an incidence of 2.27 and 0.00% in the corresponding order. Cumulative incidences of postoperative complications depending on the type of breast implants showed no significant difference; statistical significance was analyzed using the log-rank test (χ2 = 1.71, df = 1, p = 0.19). Cumulative survival of the breast implant is shown in Table 3; the Motiva Ergonomix™ showed a longer survival as compared with the BellaGel® SmoothFine (130.13 ± 13.70 vs. 120.45 ± 5.76 days). In conclusion, we describe short-term treatment outcomes and safety of an implant-based breast augmentation using two representative brands of the fifth-generation silicone gel-filled breast implants in Korean women.

Short-term Safety of Augmentation Mammaplasty Using the BellaGel Implants in Korean Women.

Asian women are stereotypically characterized by a slim body, smaller breasts and areolae, and larger nipples when compared with White women. They would therefore be vulnerable to displacement of a breast implant if they receive larger implants. They are also prone to hypertrophic and prolonged hyperemic scars. Surgeons should therefore be aware of Asian women's breast anatomy, healing tendency, and preferences. We conducted this multicenter, retrospective study to assess the short-term safety of the BellaGel implants in Korean women. METHODS: We evaluated a total of 637 women (n = 637; 1,274 breasts) for incidences of postoperative complications and the cumulative Kaplan-Meier complication-free survival. RESULTS: Overall, there were 12 cases (1.9%) of postoperative complications; these include 6 cases (0.9%) of hematoma, 2 cases (0.3%) of infection, and 4 cases (0.6%) of seroma. Moreover, there was no significant difference in the cumulative complication-free survival at 120 weeks between the 4 types of the BellaGel implants (χ2 = 2.289, P = 0.513). CONCLUSION: In conclusion, we describe the short-term safety of augmentation mammaplasty using the BellaGel implants in Korean women. But further prospective, large-scale, multicenter studies with a long period of follow-up are warranted to establish our results.

Real-time tracking of single-molecule collagenase on native collagen and partially structured collagen-mimic substrates.

The dynamic interactions of an individual matrix metalloproteinase-1 were imaged and monitored in the presence of either triple-helical or non-triple-helical, partially structured collagen-mimic substrates. The enzyme exhibited ten-fold increased catalytic turnover rates with the structurally modified substrate by skipping the triple-helix unwinding step during the catalytic pathway.

Analysis of bacterial FAMEs using gas chromatography - vacuum ultraviolet spectroscopy for the identification and discrimination of bacteria.

The identification of microorganisms is very important in different fields and alternative methods are necessary for a rapid and simple identification. The use of fatty acids for bacterial identification is gaining attention as phenotypic characteristics are reflective of the genotype and are more easily analyzed. In this work, gas chromatography-vacuum ultraviolet spectroscopy (GC-VUV) was used to determine bacteria fatty acid methyl esters (FAMEs), to identify and discriminate different environmental bacteria based on their fatty acid profile. Microorganisms were grown in agar and their fatty acids extracted, saponified, and esterified before analysis. Unique FAME profiles were obtained for each microorganism mainly composed of branched, cyclopropane, hydroxy, saturated, and unsaturated fatty acid methyl esters. S. maltophilia showed a higher diversity of fatty acids while Bacillus species showed higher complexity in terms of branched-chain FAMEs, with several iso and anteiso forms. 12 different bacteria genera and 15 species were successfully differentiated based on their fatty acid profiles after performing PCA and cluster analysis. Some difficult to differentiate species, such as Bacillus sp., which are genetically very similar, were differentiated with the developed method.

Suppression of Mammary Carcinogenesis Through Early Exposure to Dietary Lipotropes Occurs Primarily In Utero.

The study determined whether feeding during lactation affects the suppressive effect of maternal dietary lipotropes (i.e., methionine, choline, folate, and vitamin B12) on mammary carcinogenesis. Pregnant Sprague-Dawley rats were randomly allocated to the control diet during pregnancy and lactation (CC), lipotropes-fortified diet during pregnancy (LC), lipotropes-fortified diet during pregnancy plus lactation (LL), or lipotropes-fortified diet during lactation (CL). Randomly selected female offspring from each group were injected intraperitoneally with 50 mg/kg body weight of N-nitroso-N-methylurea at 50 days of age to induce mammary tumors. The LC and LL diets significantly increased tumor latency and survival (P < 0.05). Tumor volumes were significantly suppressed in LC and LL offspring as compared with the CC and CL pups (3759.1 ± 563.0 and 3603.7 ± 526.1 vs. 7465.0 ± 941.1 and 5219.3 ± 759.8 mm(3), respectively; P < 0.05). Both LC and LL lowered tumor multiplicity as compared with CC and CL (P < 0.05). The LC and LL diets repressed transcription of histone deacetylase (HDAC) 1 as well as total HDAC enzyme activity as compared with CC and CL diets (P < 0.05). Data suggest that the tumor suppressive effect of maternal dietary lipotropes is primarily in utero and may be linked to regulation of proteins involved in chromatin remodeling.

Pubertal supplementation of lipotropes in female rats reduces mammary cancer risk by suppressing histone deacetylase 1.

PURPOSE: The time from puberty to the first pregnancy is known to be important for a woman's life-time breast cancer risk. Recent studies suggest that epigenetic mechanisms may involve pubertal maturation processes, which can affect the risk of breast cancer in later life. Epigenetic alterations are related to lipotropes (methionine, choline, folate, and vitamin B12), which are methyl donors and cofactors. However, the effects of pubertal supplementation of lipotropes in breast cancer remain largely unknown. METHODS: Twenty female Sprague-Dawley rats, aged 6 weeks, were divided into two groups and fed a normal control diet or a lipotrope-fortified diet formulated to provide five times basal levels of lipotropes during puberty. All rats were injected intraperitoneally with N-nitroso-N-methylurea at 50 days of age to induce mammary tumors. RESULTS: Tumor multiplicity and tumor volume decreased significantly as a result of lipotrope supplementation. Interestingly, quantitative RT-PCR revealed significantly decreased expression of histone deacetylase 1 (Hdac1) and DNA methyltransferase 1 (Dnmt1) genes in tumor tissues of the rats supplemented with lipotrope-fortified diet, suggesting that reduced risk of breast cancer can be attributed, at least in part, to decreased expression of these two genes. CONCLUSIONS: This study demonstrates that supplementation of lipotrope-fortified diet during puberty suppresses tumor growth, potentially through down-regulating Hdac1 and Dnmt1 gene expression. Our findings suggest that pubertal methyl diet plays an important role in the etiology of breast cancer, and further studies are warranted to develop preventative strategies against breast cancer.

Clinical significance of morphologic characteristics in triple negative breast cancer.

PURPOSE: No clinically useful target molecule has been identified for triple-negative (TN) breast cancer, i.e., estrogen receptor-negative, progesterone receptor-negative, human epidermal growth factor receptor-2-negative phenotype, and its prognosis is poor. The aim of this study is to clarify the clinical and pathologic characteristics of triple negative breast cancer (TNBC). METHODS: The study subjects, 87 women with TNBC, were a subset of patients operated at Kosin University Gospel Hospital from January 2000 to December 2005. We examined pathologic characteristics such as tumor necrosis, infiltrating border, lymphocytic infiltration, prominent nucleoli in TNBC. And we studied the correlation between TNBC and several factors related to pathologic morphology. Chi-squared tests were used for statistical analysis. Kaplan-Meier estimates are presented for the survival function, and differences in survival were analyzed using the log rank test. RESULTS: Tumor necrosis was found in 51 patients (58.3%) in TNBC. And infiltrating border was found in 71 patients (81.0%). Also continuous lymphocytic distribution and prominent nucleoli was found in 31 patients (35.7%), 52 patients (59.7%), respectively. No association was detected between pathologic characteristics and other biological markers. Patients with tumor necrosis positive for TNBC didn't show shorter disease-free survival (P = 0.4490) or overall survival (P = 0.979) than patients without tumor necrosis. CONCLUSION: These findings suggest that pathologic characteristics cannot be used to classify triple-negative breast cancer into only two subtypes with differing prognoses. But because our study is small size study, more abundant patients' dates will be needed to evaluate the morphologic characteristics' predictive role.

Highly spherical and deformable chitosan microspheres for arterial embolization.

The aim of this study was to fabricate deformable chitosan (CS) microspheres for arterial embolization. CS microspheres containing poly(ethylene glycol) (PEG) were prepared by ionotropic gelation; PEG was then removed from the CS microspheres to produce the highly porous structure to allow deformability. The porosity was controlled by blending ratios of CS/PEG polymers (CS/PEG=from 100/0 to 15/85) and the effect of porosity on microcatheter delivery was examined. The size range of porous microspheres was 500-600 mum with sphericity between 1.012-1.041. Scanning electron microscope observation confirmed that microporous networks were effectively obtained by PEG extraction proportional to the initial amount of PEG. Water retention capacities, indicative of internal porosities of microspheres, increased with increasing initial amounts of blended PEG. CS microspheres with water retention values of greater than 28% exhibited noticeable deformation and smooth passage through the microcatheter tip. Novel deformable microspheres are, therefore, expected to be clinically applicable for arterial embolization.

Solubilized formulation of olmesartan medoxomil for enhancing oral bioavailability.

Olmesartan medoxomil (OLM) is an antihypertensive angiotensin II receptor blocker. OLM has a low bioavailability (BA), approximately 26% in humans, due to its low water solubility and efflux by drug resistance pumps in the gastrointestinal tract. Self-microemulsifying drug delivery system (SMEDDS), which is easily emulsified in aqueous media under gentle agitation and digestive motility, was formulated to increase the oral BA of OLM. Among the surfactants and oils studied, Capryol 90, Tween 20, and Tetraglycol were chosen and combined at a volume ratio of 1:6:3 on the basis of equilibrium solubility and phase diagram experiments. The mean droplet size of SMEDDS was 15 nm. In an oral absorption study in rats, SMEDDS formulation brought faster absorption compared to suspension, showing a T(max) value of 0.2 hr. The C(max) and AUC values of SMEDDS formulation were significantly higher than those of suspension, revealing a relative BA of about 170%. Our study demonstrated the potential usefulness of SMEDDS for the oral delivery of poorly absorbable compounds, including OLM.

Genetic organization of the putative salbostatin biosynthetic gene cluster including the 2-epi-5-epi-valiolone synthase gene in Streptomyces albus ATCC 21838.

The cyclization of sedoheptulose 7-phosphate to 2-epi-5-epi-valiolone, catalyzed by the 2-epi-5-epi-valiolone synthases, is the first committed step in the biosynthesis of C( 7 )N-aminocyclitol-containing natural products, such as validamycin and acarbose. These natural products contain in their structures a valienamine unit, which is important for their biological activity. The same core unit is also found in salbostatin, a related pseudodisaccharide that has strong trehalase inhibitory activity. In silico analysis of the putative biosynthetic gene cluster of salbostatin from Streptomyces albus ATCC 21838 revealed 20 open reading frames, including an acbC homolog gene (salQ), which is believed to be involved in the biosynthesis of salbostatin. The salQ gene was overexpressed in Escherichia coli and the catalytic function of the recombinant protein was confirmed to be a 2-epi-5-epi-valiolone synthase. In addition, SalF, SalL, SalM, SalN, SalO, and SalR were found to be homologous to AcbR, AcbM, AcbL, AcbN, AcbO, and AcbP from the acarbose pathway, respectively, which suggests that the biosynthesis of C(7)N-aminocyclitol moiety of salbostatin may be very similar to that of acarbose.

Factors affecting the apparent solubility of ursodeoxycholic acid in the grinding process.

Ursodeoxycholic acid (UDCA) was ground by a vibrating mill. Apparent solubility of the ground sample was determined by Coulter counter method. The samples were characterized by pore size distribution measurement, powder X-ray diffraction (PXRD) measurement, near infra-red (NIR) spectroscopy and contact angle measurement. The dispersive and polar components of surface free energy were calculated from the contact angle data determined by a contact angle analyzer. Surface polarity was calculated from the surface free energy components. The apparent solubility of UDCA was increased by the grinding with vibrating mill, however, the particle size of ground sample was not decreased. An amorphization was observed in the PXRD pattern of the ground sample, and the crystallinity of sample was decreased with increasing the grinding time. During the initial grinding, the dispersive component of surface free energy was decreased, whereas the polar part of surface free energy was increased. The surface polarity of the sample was increased in the same manner. Relationship between the solubility and the factors changing in the grinding process was evaluated. There was a significant correlation between the apparent solubility and the surface polarity and crystallinity of the sample. The NIR spectra confirmed the appearance of [bond]OH group on the sample surface. The apparent solubility increase of the ground sample was closely related to the improvement of the surface polarity and the destruction of crystalline structure.