Electric field control of spin-orbit torque in annealed Ta/CoFeB/HfOxheterostructures via interfacial oxidation modulation.

Electric field control of spin-orbit torque (SOT) exhibits promising potential in advanced spintronic devices through interfacial modulation. In this work, we investigate the influence of electric field and interfacial oxidation on SOT efficiency in annealed Ta/CoFeB/HfOxheterostructures. By varying annealing temperatures, the damping-like SOT efficiency reaches its peak at the annealing temperature of 320 °C, with an 80% field-free magnetization switching ratio induced by SOT having been demonstrated. This enhancement is ascribed to the annealing-induced modulation of oxygen ion migration at the CoFeB/HfOxinterface. By applying voltages across the Ta/CoFeB/HfOxheterostructures, which drives the O2‒migration across the interface, a reversible, bipolar, and non-volatile modulation of SOT efficiency was observed. The collective influence of annealing temperature and electric field effects on SOT carried out in this work provides an effective approach into facilitating the optimization and control of SOT in spintronic devices.

Granular Magnetization Switching in Pt/Co/Ti Structure with HfOx Insertion for In-Memory Computing Applications.

Exploring multiple states based on the domain wall (DW) position has garnered increased attention for in-memory computing applications, particularly focusing on the utilization of spin-orbit torque (SOT) to drive DW motion. However, devices relying on the DW position require efficient DW pinning. Here, we achieve granular magnetization switching by incorporating an HfOx insertion layer between the Co/Ti interface. This corresponds to a transition in the switching model from the DW motion to DW nucleation. Compared to the conventional Pt/Co/Ti structure, incorporation of the HfOx layer results in an enhanced SOT efficiency and a lower switching current density. We also realized stable multistate storage and synaptic plasticity by applying pulse current in the Pt/Co/HfOx/Ti device. The simulation of artificial neural networks (ANN) based on the device can perform digital recognition tasks with an accuracy rate of 91%. These results identify that DW nucleation with a Pt/Co/HfOx/Ti based device has potential applications in multistate storage and ANN.

A bi-functional three-terminal memristor applicable as an artificial synapse and neuron.

Due to their significant resemblance to the biological brain, spiking neural networks (SNNs) show promise in handling spatiotemporal information with high time and energy efficiency. Two-terminal memristors have the capability to achieve both synaptic and neuronal functions; however, such memristors face asynchronous programming/reading operation issues. Here, a three-terminal memristor (3TM) based on oxygen ion migration is developed to function as both a synapse and a neuron. We demonstrate short-term plasticity such as pair-pulse facilitation and high-pass dynamic filtering in our devices. Additionally, a 'learning-forgetting-relearning' behavior is successfully mimicked, with lower power required for the relearning process than the first learning. Furthermore, by leveraging the short-term dynamics, the leaky-integrate-and-fire neuronal model is emulated by the 3TM without adopting an external capacitor to obtain the leakage property. The proposed bi-functional 3TM offers more process compatibility for integrating synaptic and neuronal components in the hardware implementation of an SNN.

Strain-induced degradation and recovery of flexible NbOx-based threshold switching device.

We investigate the functionality of NbOx-based selector devices on a flexible substrate. It was observed that the failure mechanism of cyclic tensile strain is from the disruption of atom arrangements, which essentially led to the crack formation of the film. When under cyclic compressive strain, buckling delamination of the film occurs as the compressed films have debonded from their neighboring layers. By implementing an annealing process after the strain-induced degradation, recovery of the device is observed with reduced threshold and hold voltages. The physical mechanism of the device is investigated through Poole-Frenkel mechanism fitting, which provides insights into the switching behavior after mechanical strain and annealing process. The result demonstrates the potential of the NbOx device in flexible electronics applications with a high endurance of up to 105 cycles of cyclic bending strain and the recovery of the device after degradation.

Proton-Assisted Redox-Based Three-Terminal Memristor for Synaptic Device Applications.

Emerging technologies, i.e., spintronics, 2D materials, and memristive devices, have been widely investigated as the building block of neuromorphic computing systems. Three-terminal memristor (3TM) is specifically designed to mitigate the challenges encountered by its two-terminal counterpart as it can concurrently execute signal transmission and memory operations. In this work, we present a complementary metal-oxide-semiconductor-compatible 3TM with highly linear weight update characteristics and a dynamic range of ∼15. The switching mechanism is governed by the migration of oxygen ions and protons in and out of the channel under an external gate electric field. The involvement of the protonic defects in the electrochemical reactions is proposed based on the bipolar pulse trains required to initiate the oxidation process and the device electrical characteristics under different humidity levels. For the synaptic operation, an excellent endurance performance with over 256k synaptic weight updates was demonstrated while maintaining a stable dynamic range. Additionally, the synaptic performance of the 3TM is simulated and implemented into a four-layer neural network (NN) model, achieving an accuracy of ∼92% in MNIST handwritten digit recognition. With such desirable conductance modulation characteristics, our proposed 3T-memristor is a promising synaptic device candidate to realize the hardware implementation of the artificial NN.

The impact of oxygen vacancy defect density on the nonlinearity and short-term plasticity of TiO2-based exponential selector.

The readout margin of the one selector-one RRAM crossbar array architecture is strongly dependent on the nonlinearity of the selector device. In this work, we demonstrated that the nonlinearity of Pt/TiO2/Pt exponential selectors increases with decreasing oxygen vacancy defect density. The defect density is controlled by modulating the sputtering pressure in the oxide deposition process. Our results reveal that the dominant conduction mechanisms of the Pt/TiO2/Pt structure transit from Schottky emission to Poole-Frenkel emission with the increase of sputtering pressure. Such transition is attributed to the rise of oxygen vacancy concentration. In addition, the short-term plasticity feature of the Pt/TiO2/Pt selector is shown to be enhanced with a lower defect density. These results suggest that low defect density is necessary for improved exponential selector performances.

Enhancement of temperature-modulated NbO2-based relaxation oscillator via interfacial and bulk treatments.

This work demonstrates oscillation frequency modulation in a NbO2-based relaxation oscillator device, in which the oscillation frequency increases with operating temperature and source voltage, and decreases with load resistance. An annealing-induced oxygen diffusion at 373 K was carried out to optimize the stoichiometry of the bulk NbO2to achieve consistent oscillation frequency shift with device temperature. The device exhibits stable self-sustained oscillation in which the frequency can be modulated between 2 and 33 MHz, and a wider operating voltage range can be obtained. An additional surface treatment step was employed during fabrication to reduce the surface roughness of the bottom electrode and to remove surface contaminants that affect the interfacial properties of the device. The device frequency tunability coupled with high oscillating frequency and high endurance capability of more than 1.5 × 108cycles indicates that the Pt/NbO2/Pt device is particularly suitable for applications in an oscillatory neural network.

Healthcare utilization and health-related quality of life of severe asthma patients in Singapore.

BACKGROUND: Notwithstanding unequivocal consensus on the disproportionate effect of severe asthma (SA) on asthma morbidity, healthcare utilization, quality of life, work impairment and socioeconomic burden, the burden of SA patients in Singapore has not been appraised. OBJECTIVES: To determine the burden of disease and extent of quality of life impairment in SA patients in Singapore. METHODS: A cross-sectional analysis of SA patients seen in Singapore General Hospital (2020-2021) to investigate emergency healthcare utilization, oral corticosteroid (OCS) burden and health-related quality of life (HRQoL) with primary endpoint EuroQoL-5 Dimension three-level (EQ-5D-3L) scores. The empirical measurement properties of the EQ-5D utility index in SA were comprehensively assessed through multivariate regression analyses. RESULTS: A total of 336 SA patients were recruited, 51.2% of SA patients had at least one acute healthcare resource utilization during the previous year, with 25.6% of patients having an emergency healthcare visit to the hospital. Overall mean (SD) EQ-5D-3L and EQ-5D-3L utility scores in SA patients were 6.22 (1.51) and 0.77 (0.30), respectively. EQ-5D utility scores were 0.14 lower in uncontrolled vs controlled asthma and 0.09 lower in the presence of severe exacerbation, whereas barely changed by maintenance OCS dose and airflow limitation. CONCLUSION: SA patients were found to have high disease burden, high healthcare resource utilization and OCS use, low biologics usage, poor HRQoL and utility in comparison with other chronic diseases.

Frequency-Dependent Synapse Weight Tuning in 1S1R with a Short-Term Plasticity TiOx-Based Exponential Selector.

Short-term plasticity (STP) is an important synaptic characteristic in the hardware implementation of artificial neural networks (ANN), as it enables the temporal information processing (TIP) capability. However, the STP feature is rather challenging to reproduce from a single nonvolatile resistive random-access memory (RRAM) element, as it requires a certain degree of volatility. In this work, a Pt/TiOx/Pt exponential selector is introduced not only to suppress the sneak current but also to enable the TIP feature in a one selector-one RRAM (1S1R) synaptic device. Our measurements reveal that the exponential selector exhibits the STP characteristic, while a Pt/HfOx/Ti RRAM enables the long-term memory capability of the synapse. Thereafter, we experimentally demonstrated pulse frequency-dependent multilevel switching in the 1S1R device, exhibiting the TIP capability of the developed 1S1R synapse. The observed STP of the selector is strongly influenced by the bottom metal-oxide interface, in which Ar plasma treatment on the bottom Pt electrode resulted in the annihilation of the STP feature in the selector. A mechanism is thus proposed to explain the observed STP, using the local electric field enhancement induced at the metal-oxide interface coupled with the drift-diffusion model of mobile O2- and Ti3+ ions. This work therefore provides a reliable means of producing the STP feature in a 1S1R device, which demonstrates the TIP capability sought after in hardware-based ANN.

Spin Reflection-Induced Field-Free Magnetization Switching in Perpendicularly Magnetized MgO/Pt/Co Heterostructures.

Field-free magnetization switching is critical towards practical, integrated spin-orbit torque (SOT)-driven magnetic random-access memory with perpendicular magnetic anisotropy. Our work proposes a technique to modulate the spin reflection and spin density of states within a heavy-metal Pt through interfacing with a dielectric MgO layer. We demonstrate tunability of the effective out-of-plane spin torque acting on the ferromagnetic Co layer, enabling current-induced SOT magnetization switching without the assistance of an external magnetic field. The influence of the MgO layer thickness on effective SOT efficiency shows saturation at 4 nm, while up to 80% of field-free magnetization switching ratio is achieved with the MgO between 5 and 8 nm. We analyze and attribute the complex interaction to spin reflection at the dielectric/heavy metal interface and spin scattering within the dielectric medium due to interfacial electric fields. Further, through substituting the dielectric with Ti or Pt, we confirm that the MgO layer is indeed responsible for the observed field-free magnetization switching mechanism.

Magnetic Soft Millirobots 3D Printed by Circulating Vat Photopolymerization to Manipulate Droplets Containing Hazardous Agents for In Vitro Diagnostics.

3D printing via vat photopolymerization (VP) is a highly promising approach for fabricating magnetic soft millirobots (MSMRs) with accurate miniature 3D structures; however, magnetic filler materials added to resin either strongly interfere with the photon energy source or sediment too fast, resulting in the nonuniformity of the filler distribution or failed prints, which limits the application of VP. To this end, a circulating vat photopolymerization (CVP) platform that can print MSMRs with high uniformity, high particle loading, and strong magnetic response is presented. After extensive characterization of materials and 3D printed parts, it is found that SrFe12 O19 is an ideal magnetic filler for CVP and can be printed with 30% particle loading and high uniformity. By using CVP, various tethered and untethered MSMRs are 3D printed monolithically and demonstrate the capability of reversible 3D-to-3D transformation and liquid droplet manipulation in 3D, an important task for in vitro diagnostics that are not shown with conventional MSMRs. A fully automated liquid droplet handling platform that manipulates droplets with MSMR is presented for detecting carbapenem antibiotic resistance in hazardous biosamples as a proof of concept, and the results agree with the benchmark.

Dependence of spin-orbit torque effective fields on magnetization uniformity in Ta/Co/Pt structure.

The spin-orbit torque (SOT) effective fields, namely field-like and damping-like terms, depend on the thicknesses of heavy metal (HM) and ferromagnetic metal (FM) layers, in a stack comprising of HM/FM/HM or oxide. In this work, we report on the dependence of the SOT effective fields on the magnetization uniformity in the wires comprising of Ta/Co/Pt layer structure. SOT dependence on magnetization uniformity dependence was investigated by concurrent variation of the magnetization uniformity in Co layer and characterization of the SOT effective fields in each wire which excludes the layer thickness dependence influences. Our experimental results reveal that the field-like term decreases while the damping-like term increases with increasing Co magnetization uniformity. The magnetization uniformity influence on the effective fields is attributed to the spin Hall effect, which contributes to the SOT.

Financial Toxicity After Cancer in a Setting With Universal Health Coverage: A Call for Urgent Action.

BACKGROUND: Financial toxicity negatively affects the well-being of cancer survivors. We examined the incidence, cost drivers, and factors associated with financial toxicity after cancer in an upper-middle-income country with universal health coverage. METHODS: Through the Association of Southeast Asian Nations Costs in Oncology study, 1,294 newly diagnosed patients with cancer (Ministry of Health [MOH] hospitals [n = 577], a public university hospital [n = 642], private hospitals [n = 75]) were observed in Malaysia. Cost diaries and questionnaires were used to measure incidence of financial toxicity, encompassing financial catastrophe (FC; out-of-pocket costs ≥ 30% of annual household income), medical impoverishment (decrease in household income from above the national poverty line to below that line after subtraction of cancer-related costs), and economic hardship (inability to make necessary household payments). Predictors of financial toxicity were determined using multivariable analyses. RESULTS: One fifth of patients had private health insurance. Incidence of FC at 1 year was 51% (MOH hospitals, 33%; public university hospital, 65%; private hospitals, 72%). Thirty-three percent of households were impoverished at 1 year. Economic hardship was reported by 47% of families. Risk of FC attributed to conventional medical care alone was 18% (MOH hospitals, 5%; public university hospital, 24%; private hospitals, 67%). Inclusion of expenditures on nonmedical goods and services inflated the risk of financial toxicity in public hospitals. Low-income status, type of hospital, and lack of health insurance were strong predictors of FC. CONCLUSION: Patients with cancer may not be fully protected against financial hardships, even in settings with universal health coverage. Nonmedical costs also contribute as important drivers of financial toxicity in these settings.

Health-related quality of life and psychological distress among cancer survivors in a middle-income country.

OBJECTIVES: Quality of life and psychological well-being are important patient-centered outcomes, which are useful in evaluation of cancer care delivery. However, evidence from low-income and middle-income countries remains scarce. We assessed health-related quality of life (HRQoL) and prevalence of psychological distress (anxiety or depression), as well as their predictors, among cancer survivors in a middle-income setting. METHODS: Through the Association of Southeast Asian Nations Costs in Oncology study, 1490 newly diagnosed cancer patients were followed-up in Malaysia for 1 year. Health-related quality of life was assessed by using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core 30 (EORTC QLQ-C30) and EuroQol-5 (EQ-5D) dimension questionnaires at baseline, 3 and 12 months. Psychological distress was assessed by using Hospital Anxiety and Depression Scale. Data were modeled by using general linear and logistic regressions analyses. RESULTS: One year after diagnosis, the mean EORTC QLQ-C30 Global Health score of the cancer survivors remained low at 53.0 over 100 (SD 21.4). Fifty-four percent of survivors reported at least moderate levels of anxiety, while 27% had at least moderate levels of depression. Late stage at diagnosis was the strongest predictor of low HRQoL. Increasing age, being married, high-income status, hospital type, presence of comorbidities, and chemotherapy administration were also associated with worse HRQoL. The significant predictors of psychological distress were cancer stage and hospital type. CONCLUSION: Cancer survivors in this middle-income setting have persistently impaired HRQoL and high levels of psychological distress. Development of a holistic cancer survivorship program addressing wider aspects of well-being is urgently needed in our settings.

Radiotherapy utilization in developing countries: An IAEA study.

BACKGROUND: The planning of national radiotherapy (RT) services requires a thorough knowledge of the country's cancer epidemiology profile, the radiotherapy utilization (RTU) rates and a future projection of these data. Previous studies have established RTU rates in high-income countries. METHODS: Optimal RTU (oRTU) rates were determined for nine middle-income countries, following the epidemiological evidence-based method. The actual RTU (aRTU) rates were calculated dividing the total number of new notifiable cancer patients treated with radiotherapy in 2012 by the total number of cancer patients diagnosed in the same year in each country. An analysis of the characteristics of patients and treatments in a series of 300 consecutive radiotherapy patients shed light on the particular patient and treatments profile in the participating countries. RESULTS: The median oRTU rate for the group of nine countries was 52% (47-56%). The median aRTU rate for the nine countries was 28% (9-46%). These results show that the real proportion of cancer patients receiving RT is lower than the optimal RTU with a rate difference between 10-42.7%. The median percent-unmet need was 47% (18-82.3%). CONCLUSIONS: The optimal RTU rate in middle-income countries did not differ significantly from that previously found in high-income countries. The actual RTU rates were consistently lower than the optimal, in particular in countries with limited resources and a large population.

Optimal radiotherapy utilisation rate in developing countries: An IAEA study.

Optimal radiotherapy utilisation rate (RTU) is the proportion of all cancer cases that should receive radiotherapy. Optimal RTU was estimated for 9 Middle Income Countries as part of a larger IAEA project to better understand RTU and stage distribution.

Role of genetic & environment risk factors in the aetiology of colorectal cancer in Malaysia.

BACKGROUND & OBJECTIVES: Colorectal cancer (CRC) is second only to breast cancer as the leading cause of cancer-related deaths in Malaysia. In the Asia-Pacific area, it is the highest emerging gastrointestinal cancer. The aim of this study was to identify single nucleotide polymorphisms (SNPs) and environmental factors associated with CRC risk in Malaysia from a panel of cancer associated SNPs. METHODS: In this case-control study, 160 Malaysian subjects were recruited, including both with CRC and controls. A total of 768 SNPs were genotyped and analyzed to distinguish risk and protective alleles. Genotyping was carried out using Illumina's BeadArray platform. Information on blood group, occupation, medical history, family history of cancer, intake of red meat and vegetables, exposure to radiation, smoking and drinking habits, etc was collected. Odds ratio (OR), 95% confidence interval (CI) were calculated. RESULTS: A panel of 23 SNPs significantly associated with colorectal cancer risk was identified (P<0.01). Of these, 12 SNPs increased the risk of CRC and 11 reduced the risk. Among the environmental risk factors investigated, high intake of red meat (more than 50% daily proportion) was found to be significantly associated with increased risk of CRC (OR=6.52, 95% CI :1.93-2.04, P=0.003). Two SNPs including rs2069521 and rs10046 in genes of cytochrome P450 (CYP) superfamily were found significantly associated with CRC risk. For gene-environment analysis, the A allele of rs2069521 showed a significant association with CRC risk when stratified by red meat intake. INTERPRETATION & CONCLUSIONS: In this preliminary study, a panel of SNPs found to be significantly associated with CRC in Malaysian population, was identified. Also, red meat consumption and lack of physical exercise were risk factors for CRC, while consumption of fruits and vegetables served as protective factor.

Closing the global cancer divide--performance of breast cancer care services in a middle income developing country.

BACKGROUND: Cancer is the leading cause of deaths in the world. A widening disparity in cancer burden has emerged between high income and low-middle income countries. Closing this cancer divide is an ethical imperative but there is a dearth of data on cancer services from developing countries. METHODS: This was a multi-center, retrospective observational cohort study which enrolled women with breast cancer (BC) attending 8 participating cancer centers in Malaysia in 2011. All patients were followed up for 12 months from diagnosis to determine their access to therapies. We assess care performance using measures developed by Quality Oncology Practice Initiative, American Society of Clinical Oncology/National Comprehensive Cancer Network, American College of Surgeons' National Accreditation Program for Breast Centers as well as our local guideline. RESULTS: Seven hundred and fifty seven patients were included in the study; they represent about 20% of incident BC in Malaysia. Performance results were mixed. Late presentation was 40%. Access to diagnostic and breast surgery services were timely; the interval from presentation to tissue diagnosis was short (median = 9 days), and all who needed surgery could receive it with only a short wait (median = 11 days). Performance of radiation, chemo and hormonal therapy services showed that about 75 to 80% of patients could access these treatments timely, and those who could not were because they sought alternative treatment or they refused treatment. Access to Trastuzumab was limited to only 19% of eligible patients. CONCLUSIONS: These performance results are probably acceptable for a middle income country though far below the 95% or higher adherence rates routinely reported by centres in developed countries. High cost trastuzumab was inaccessible to this population without public funding support.

Overview of cancer in Malaysia.

The problem of cancer in Malaysia is a growing one. It is now the fourth leading cause of death among medically certified deaths. Cancer of the lung is the most common killer among malignancies. It is estimated that the annual incidence of cancer is 30 000. The majority of patients are found at a late stage of the disease. The National Cancer Control Program aims to reduce the incidence and mortality of cancer and to improve the quality of life of cancer patients. Policies encompass prevention, early diagnosis, treatment, palliative care and rehabilitation. The program for prevention includes an anti-smoking campaign and immunization of babies against hepatitis B. Papanicolaou's smear and breast self-examination are among efforts for the early detection of cancer. Public education and the promotion of healthy lifestyles have been actively carried out. Facilities for treatment and palliative care are being developed further. Networks between the public and private sectors and non-governmental organizations have been on-going. Apart from the establishment and upgrading of treatment facilities, the need for training of skilled staff in the treatment of cancer is highlighted.