Etching of transition metals is one of the major challenges in magnetic random-access memory fabrication. In this work, atomic layer etching of iron surfaces with halogen and an organic molecule was studied. The authors successfully etched Fe thin films by forming volatile metal complexes at low temperature with cyclic reactions of Cl2 and acetylacetone (acac). The mechanism of acac reacting on Cl-modified Fe surface was investigated: the surface was first activated with Cl2 gas, and then the top layer of metal was removed by acac reaction. The extent of Cl2 reaction determined the etching rate. At substrate temperatures lower than 135 °C, acac could not remove chlorine. In situ x-ray photoelectron spectroscopy and density functional theory simulation show that the reaction of acac on Cl-dosed Fe surface is likely following a complex pathway instead of simple acac substitution for Cl2. Acac decomposition may play an important role in the process.

The surface passivation of p-benzoquinone (BQ) and hydroquinone (HQ) when dissolved in methanol (ME) have been examined through effective lifetime testing of crystalline silicon (c-Si) wafers treated with the aforementioned solutions. Changes in the availability of both photons and protons in the solutions were demonstrated to affect the level of passivation achieved. The requirement of both excess protons and ambient light exposure to maintain high effective lifetimes supports the presence of a free radical species that drives the surface passivation. Surface analysis suggests a 1:1 ratio of HQ-like bonds to methoxy bonds on the c-Si surface after treatment with a BQ/ME solution.

Background and aimsExisting assessments of the time-trends of opioid-related mortality, hospitalization and emergency department visits in Canada have relied mainly on provincial databases, while national assessments generally do not provide information before 2016. We aimed to estimate Canadian national time trends in opioid-related mortality from 2000 to 2017 and opioid-related hospitalization and emergency department visits between 2000 and 2012.Design Retrospective cohort study. Setting and participants Residents of all Canadian provinces and territories for which comparable data were available from 2000 to 2017. Measurements We identified opioid-related mortality, hospitalization and emergency department visits using validated algorithms using ICD codes from administrative databases. We calculated crude rates and sex-and age-adjusted rates per million. For hospitalizations, we calculated case-fatality, 90-day and 365-day all-cause mortality and opioid-related re-hospitalization rates. We used Poisson regression to examine the significance of the time trend. Findings From 2000 to 2017, the adjusted opioid mortality rate in Canada (outside Quebec) increased significantly by 592.9% (from 20.0 opioid deaths per million in 2000 to 118.3 in 2017). The highest year-to-year increases were from 2015 to 2016 (31.8%) and from 2016 to 2017 (52.2%). The adjusted hospitalizations doubled significantly during the study period (an increase of 103.7%, from 159.7 opioid hospitalizations per million Canadians in 2000 to 325.3 in 2012). The adjusted rate of emergency department visits increased significantly by 188.7% (from 280.6 per million in 2000 to 810.1 in 2012). Case-fatality was 2.3% overall and was mainly constant during the study period. Both 90-and 365-day all-cause mortality increased significantly between 2000 and 2011 (from 1.7 to 3.1% and 3.9 to 7.4%, respectively), while re-hospitalization for opioid-related diagnoses was reduced (from 7.8 to 6.4% and 14.2 to 12.9%, respectively). Conclusions Opioid-related mortality, hospitalization and emergency department visits in Canada have been increasing gradually since 2000.

With the application of computer and network technology in the field of accounting, the development of accounting informationization is an inevitable trend, and the construction of accounting statement data into the data warehouse will be the basis of intelligent decision-making. The complexity of industry accounting statements and the arbitrariness and diversity of users’ needs for obtaining information using statements limit the development, popularization, and application of industry accounting statements. As a block encryption algorithm, the Data Encryption Standard (DES) algorithm uses 64-bit packet data for encryption and decryption. Each eighth bit of the key is used as a parity bit; that is, the actual key length is 56 bits. Encryption and decryption use the same algorithm structure, but the order in which the subkeys are used is reversed. Under the control of the subkey, inputting 64-bit plaintext can produce 64-bit ciphertext output; otherwise, inputting 64-bit ciphertext can produce 64-bit plaintext output. The confidentiality of the DES algorithm depends on the key, and only a very small number of keys are considered weak keys, which can be easily avoided in practical applications. The 3DES algorithm is a cascade of the DES algorithm, and its encryption process is based on the DES algorithm principle. This article explains the encryption process of the DES algorithm and introduces the composition of the 3DES algorithm. The experimental results show that the 3DES encryption algorithm still has a better encryption effect and “avalanche effect” than before the improvement. In addition, for the 3DES algorithm, its encryption efficiency has not been greatly affected. The 3DES encryption algorithm achieves one encryption process at a time to some extent, can effectively resist exhaustive search attacks, and enhance the security of the DES algorithm.

This work confirms that radical intermediates are the reactive species in quinhydrone/methanol (QHY/ME) passivation on silicon surfaces. The two constituent parts, p-benzoquinone (BQ) and hydroquinone (HQ), have been studied separately. BQ abstracts the hydrogen atom from methanol to become semiquinone radicals (QH*). Both QH* and the resulting methanol radical are responsible for the large, instantaneous increase in minority carrier lifetime in BQ/ME, obtaining the lowest surface recombination velocity of 1.6 cm/s. HQ releases a hydrogen atom to become QH*. The quinone derivatives containing a lower electronegativity group (Cl or O) on the benzene ring form radicals more easily, and give better passivation results. This radical-driven passivation mechanism is also valid on other radical sources. X-ray photoelectron spectroscopy (XPS) supports the radical mechanism in the observation of dominating BQ bonding after 1 h of BQ/ME treatment, and increasing methanol bonding with increasing immersion time, reaching a roughly 21% SiOSi, 13% ME, and 6% BQ monolayer coverage in 24 h for BQ/ME passivated silicon. Density functional theory (DFT) further confirms the thermodynamic possibility of radical bonding and proves that the “edge-on” single-bonded configuration is more energetically favorable than the “face-on” double-bonded configuration.