Machine Learning for Electrocatalyst and Photocatalyst Design and Discovery

Electrocatalysts and photocatalysts are key to a sustainable future, generating clean fuels, reducing the impact of global warming, and providing solutions to environmental pollution. Improved processes for catalyst design and a better understanding of electro/photocatalytic processes are essential for improving catalyst effectiveness. Recent advances in data science and artificial intelligence have great potential to accelerate electrocatalysis and photocatalysis research, particularly the rapid exploration of large materials chemistry spaces through machine learning. Here a comprehensive introduction to, and critical review of, machine learning techniques used in electrocatalysis and photocatalysis research are provided. Sources of electro/photocatalyst data and current approaches to representing these materials by mathematical features are described, the most commonly used machine learning methods summarized, and the quality and utility of electro/photocatalyst models evaluated. Illustrations of how machine learning models are applied to novel electro/photocatalyst discovery and used to elucidate electrocatalytic or photocatalytic reaction mechanisms are provided. The review offers a guide for materials scientists on the selection of machine learning methods for electrocatalysis and photocatalysis research. The application of machine learning to catalysis science represents a paradigm shift in the way advanced, next-generation catalysts will be designed and synthesized.

Flexible sigmoidoscopy may be ineffective for secondary prevention of colorectal cancer in asymptomatic, average-risk men

Asymptomatic men (N = 114) 50 years of age or older had screening for colorectal neoplasia with flexible sigmoidoscopy followed by colonoscopy regardless of the sigmoidoscopic result. Our study objective was to determine the prevalence of patients having isolated adenomatous polyps in a proximal colonic segment in the absence of a distal index neoplasm within reach of the sigmoidoscope. Through the combined use of sigmoidoscopy and colonoscopy, adenomatous polyps were detected in 47 of 114 individuals (41%). A total of 88 adenomas was found. Seventeen patients had isolated neoplasms in proximal colonic segments in the absence of distal adenomas. These patients represented 15% of screened subjects (17 of 114) and 20% of individuals who lacked adenomas on sigmoidoscopy (17 of 84). The majority of proximal neoplasms were small (less than 1.0 cm), tubular adenomas. Flexible sigmoidoscopy may be ineffective for screening asymptomatic men for neoplasia. However, it remains to be determined if a 20% miss rate (for those with a normal sigmoidoscopic examination) is significant and whether small proximal adenomas are worth finding.

Developing sustainable, high-performance perovskites in photocatalysis: design strategies and applications

Solar energy is attractive because it is free, renewable, abundant and sustainable. Photocatalysis is one of the feasible routes to utilize solar energy for the degradation of pollutants and the production of fuel. Perovskites and their derivatives have received substantial attention in both photocatalytic wastewater treatment and energy production because of their highly tailorable structural and physicochemical properties. This review illustrates the basic principles of photocatalytic reactions and the application of these principles to the design of robust and sustainable perovskite photocatalysts. It details the structures of the perovskites and the physics and chemistry behind photocatalytic reactions and describes the advantages and limitations of popular strategies for the design of photoactive perovskites. This is followed by examples of how these strategies are applied to enhance the photocatalytic efficiency of oxide, halide and oxyhalide perovskites, with a focus on materials with potential for practical application, that is, not containing scarce or toxic elements. It is expected that this overview of the development of photocatalysts and deeper understanding of photocatalytic principles will accelerate the exploitation of efficient perovskite photocatalysts and bring about effective solutions to the energy and environmental crisis.

Anti-epidermal growth factor receptor (EGFR) monoclonal antibody combined with cisplatin and 5-fluorouracil in patients with metastatic nasopharyngeal carcinoma after radical radiotherapy: a multicentre, open-label, phase II clinical trial

BACKGROUND

We conducted a single-arm phase II trial to evaluate the efficacy and adverse effects (AEs) of an anti-epidermal growth factor receptor monoclonal antibody, nimotuzumab, combined with cisplatin and 5-fluorouracil (PF) as first-line treatment in recurrent metastatic nasopharyngeal carcinoma after radical radiotherapy.

METHODS

Patients who met the eligibility criteria were recruited from ten institutions (ClinicalTrials.gov; NCT01616849). A Simon optimal two-stage design was used to calculate the sample size. All patients received weekly nimotuzumab (200 mg) added to cisplatin (100 mg/m2 D1) and 5-fluorouracil (4 g/m2 continuous infusion D1-4) every 3-weekly for a maximum of six cycles. Primary end point was objective response rate (ORR). Secondary end points included disease control rate (DCR), progression-free survival (PFS), overall survival (OS) and AEs.

RESULTS

A total of 35 patients were enrolled (13 in stage 1 and 22 in stage 2). Overall ORR and DCR were 71.4% (25/35) and 85.7% (30/35), respectively. Median PFS and OS were 7.0 (95% CI 5.8-8.2) months and 16.3 (95% CI 11.4-21.3) months, respectively. Unplanned exploratory analyses suggest that patients who received ≥2400 mg nimotuzumab and ≥4 cycles of PF had superior ORR, PFS and OS than those who did not (88.9% versus 12.5%, P < 0.001; 7.4 versus 2.7 months, P = 0.081; 17.0 versus 8.0 months, P = 0.202). Favourable subgroups included patients with lung metastasis [HROS 0.324 (95% CI 0.146-0.717), P = 0.008] and disease-free interval of >12 months [HROS 0.307 (95% CI 0.131-0.724), P = 0.004], but no difference was observed for metastatic burden. The only major grade 3/4 AE was leukopenia (62.9%).

CONCLUSION

Combination nimotuzumab-PF chemotherapy demonstrates potential efficacy, and is well tolerated as first-line chemotherapy regimen in recurrent metastatic nasopharyngeal carcinoma.

Size-dependent influence of NOx on the growth rates of organic aerosol particles

Atmospheric new-particle formation (NPF) affects climate by contributing to a large fraction of the cloud condensation nuclei (CCN). Highly oxygenated organic molecules (HOMs) drive the early particle growth and therefore substantially influence the survival of newly formed particles to CCN. Nitrogen oxide (NOx) is known to suppress the NPF driven by HOMs, but the underlying mechanism remains largely unclear. Here, we examine the response of particle growth to the changes of HOM formation caused by NOx. We show that NOx suppresses particle growth in general, but the suppression is rather nonuniform and size dependent, which can be quantitatively explained by the shifted HOM volatility after adding NOx. By illustrating how NOx affects the early growth of new particles, a critical step of CCN formation, our results help provide a refined assessment of the potential climatic effects caused by the diverse changes of NOx level in forest regions around the globe.

Hierarchically Porous WO3/CdWO4 Fiber-in-Tube Nanostructures Featuring Readily Accessible Active Sites and Enhanced Photocatalytic Effectiveness for Antibiotic Degradation in Water

The intentional design and construction of photocatalysts containing heterojunctions with readily accessible active sites will improve their ability to degrade pollutants. Herein, hierarchically porous WO₃/CdWO₄ fiber-in-tube nanostructures with three accessible surfaces (surface of core fiber and inner and outer surfaces of the porous tube shell) were fabricated by an electrospinning method. This WO₃/CdWO₄ heterostructure, assembled by interconnected nanoparticles, displays good photocatalytic degradation of ciprofloxacin (CIP, 93.4%) and tetracycline (TC, 81.6%) after 90 min of simulated sunlight irradiation, much higher than the pristine WO₃ (<75.3% for CIP and <53.6% for TC) or CdWO₄ materials (<58.9% for CIP and <39.5% for TC). The WO₃/CdWO₄ fiber-in-tube promotes the separation of photoinduced electrons and holes and also provides readily accessible reaction sites for photocatalytic degradation. The dominant active species determined by trapping active species and electron paramagnetic resonance were hydroxyl radicals followed by photogenerated holes and superoxide anions. The WO₃/CdWO₄ materials formed a Z-scheme heterojunction that generated superoxide anion and hydroxyl radicals, leading to degradation of antibiotics (CIP and TC) via photocatalysis in aqueous solution.

Plasminogen activation in lesional skin of Pemphigus vulgaris type Neumann

Zymographic and immunological studies revealed that primarily tissue-type plasminogen activator and to a lesser extent urokinase-type plasminogen activator were present in fluids of pemphigus vulgaris (type Neumann) skin blisters. Furthermore, plasmin activity was detected in pemphigus blister fluids using chromogenic peptide substrate assays. In pemphigus, but not in control, suction blister fluids plasmin/alpha 2-antiplasmin and plasmin/alpha 2-macroglobulin complexes were found by immunoprecipitation or by testing in immunoassays after fractionation by molecular-sieve chromatography. Plasmin activity, detected by a low molecular weight chromogenic peptide assay, was ascribed to plasmin/alpha 2-macroglobulin complexes. Since formation of plasmin/inhibitor complexes requires active plasmin, the finding indicates previous activation of plasminogen in pemphigus lesions.

Reimbursement recommendations for cancer drugs supported by phase II evidence in Canada

Background

Phase ii data are increasingly being used as primary evidence for public reimbursement for oncologic drugs. We compared the frequency of reimbursement recommendations for phase ii and phase iii submissions and assessed for variables associated with a positive or conditional recommendation.

Methods

We identified submissions made to the pan-Canadian Oncology Drug Review's Expert Review Committee (perc), of the Canadian Agency for Drugs and Technologies in Health, July 2011 to July 2019, that were supported only by phase ii data. We identified variables within the perc's deliberative framework, including clinical and economic factors, associated with the final reimbursement recommendation. We conducted a multivariable analysis with logistic regression for these variables: feasibility of phase iii study, hematologic indication, and unmet need.

Results

We identified 139 submissions with a perc final recommendation. In 27 instances (19%), the submission had only phase ii evidence, and a positive recommendation was issued for 63% of them (the positive recommendation rate was 82% for submissions with phase iii evidence). Clinical benefit (p < 0.001), unmet need (p = 0.047), and patient alignment (p = 0.015) were associated with a positive recommendation. If a future phase iii study was deemed feasible for submissions with only phase ii evidence, then in univariable (p = 0.040) and multivariable analysis (p = 0.024), the perc was less likely to recommend reimbursement (odds ratio: 0.132).

Conclusions

Although more than half the oncologic submissions with phase ii data were recommended for public reimbursement, compared with submissions having phase iii data, they were less likely to be recommended. A positive or conditional recommendation was more likely if clinical benefit and alignment with patient values was demonstrated. The perc was less likely to recommend reimbursement for submissions with phase ii evidence if a phase iii trial was deemed possible.

Use of metamodels for rapid discovery of narrow bandgap oxide photocatalysts

New photocatalysts are traditionally identified through trial-and-error methods. Machine learning has shown considerable promise for improving the efficiency of photocatalyst discovery from a large potential pool. Here, we describe a multi-step, target-driven consensus method using a stacking meta-learning algorithm that robustly predicts bandgaps and H2 evolution activities of photocatalysts. Trained on small datasets, these models can rapidly screen a large space (>10 million materials) to identify promising, non-toxic compounds as candidate water splitting photocatalysts. Two effective compounds and two controls possessing optimal bandgap values (∼2 eV) but not photoactivity as predicted by the models were synthesized. Their experimentally measured bandgaps and H2 evolution activities were consistent with the predictions. Conspicuously, the two compounds with strong photoactivities under UV and visible light are promising visible-light-driven water splitting photocatalysts. This study demonstrates the power of machine learning and the potential of big data to accelerate discovery of next-generation photocatalysts.

Impact of the pan-Canadian Oncology Drug Review on provincial concordance with respect to cancer drug funding decisions and time to funding

BACKGROUND

The pan-Canadian Oncology Drug Review (pcodr) was implemented in 2011 to address uneven drug coverage and lack of transparency with respect to the various provincial cancer drug review processes in Canada. We evaluated the impact of the pcodr on provincial decision concordance and time from Notice of Compliance (noc) to drug funding.

METHODS

In a retrospective review, Health Canada's Drug Product Database was used to identify new indications for cancer drugs between January 2003 and May 2014, and provincial formulary listings for drug-funding dates and decisions between 1 January 2003 and 31 December 2014 were retrieved. Multiple linear models and quantile regressions were used to evaluate changes in time to decision-making before and after the implementation of the pcodr. Agreement of decisions between provinces was evaluated using kappa statistics.

RESULTS

Data were available from 9 provinces (all Canadian provinces except Quebec), identifying 88 indications that represented 51 unique cancer drugs. Two provinces lacked available data for all 88 indications at the time of data collection. Interprovincial concordance in drug funding decisions significantly increased after the pcodr's implementation (Brennan-Prediger coefficient: 0.54 pre-pcodr vs. 0.78 post-pcodr; p = 0.002). Nationwide, the median number of days from Health Canada's noc date to the date of funding significantly declined (to 393 days from 522 days, p < 0.001). Exploratory analyses excluding provinces with incomplete data did not change the results.

CONCLUSIONS

After the implementation of the pcodr, greater concordance in cancer drug funding decisions between provinces and decreased time to funding decisions were observed.

Synthesis of Layered Lead-Free Perovskite Nanocrystals with Precise Size and Shape Control and Their Photocatalytic Activity

Halide perovskites have attracted enormous attention due to their potential applications in optoelectronics and photocatalysis. However, concerns over their instability, toxicity, and unsatisfactory efficiency have necessitated the development of lead-free all-inorganic halide perovskites. A major challenge in designing efficient halide perovskites for practical applications is the lack of effective methods for producing nanocrystals with precise size and shape control. In this work, a layered perovskite, Cs4ZnSb2Cl12 (CZS), is found from calculations to exhibit size- and facet-dependent optoelectronic properties in the nanoscale, and thus, a colloidal method is used to synthesize the CZS nanoparticles with size-tunable morphologies: zero- (nanodots), one- (nanowires and nanorods), two- (nanoplates), and three-dimensional (nanopolyhedra). The growth kinetics of the CZS nanostructures, along with the effects of surface ligands, reaction temperature, and time were investigated. The optoelectronic properties of the nanocrystals varied with size due to quantum confinement effects and with shape due to anisotropy within the crystals and the exposure of specific facets. These properties could be modulated to enhance the visible-light photocatalytic performance for toluene oxidation. In particular, the 9.7 nm CZS nanoplates displayed a toluene to benzaldehyde conversion rate of 1893 μmol g-1 h-1 (95% selectivity), 500 times higher than the bulk synthesized CZS, and comparable with the reported photocatalysts. This study demonstrates the integration of theoretical calculations and synthesis, revealing an approach to the design and fabrication of novel, high-performance colloidal perovskite nanocrystals for optoelectronic and photocatalytic applications.

Rapamycin, mycophenolate mofetil, methylprednisolone, and cytotoxic T-lymphocyte-associated antigen 4 immunoglobulin-based conditioning regimen to induce partial tolerance to hind limb allografts without cytoreductive conditioning

BACKGROUND

Composite tissue allograft transplantation may represent the next frontier in the field of reconstructive surgery. However, the main obstacles precluding the routine use of composite tissue allotransplants are rejection and toxicity associated with life-long immunosuppressive therapy. In this study, we investigated a nontoxic immunosuppressant and cytotoxic T-lymphocyte-associated antigen 4 immunoglobulin (CTLA4-Ig)-based protocol to induce donor-specific tolerance to hind limb allografts in rats.

METHODS

Fully mismatched, 4- to 10-week-old Brown Norway (BN, RT1n) and Lewis (RT1) rats were used as cell/organ donors and recipients, respectively. Recipients were treated with CTLA4-Ig (2 mg/kg/d) on days -30, -28, -26, -24, and -22, rapamycin, mycophenolate mofetil, and methylprednisolone (RAPA/MMF/MP) combined therapy (from days -30 to day 100), a single dose of anti-lymphocyte serum (10 mg, on day -30), and donor bone marrow (10 x 10(7) T-cell-depleted cells) transplantation (BMT, on day -30). Thirty days after BMT, chimeric animals received hind limb allotransplantations (on day 0). The RAPA/MMF/MP combined therapy was changed to Cyclosporine (CsA, 8 mg/kg/d) on day 100 and maintained thereafter at this level.

RESULTS

Hematopoietic chimerism of 17.6 +/- 9.5% at day 0, was stable (15.2 +/- 5.6%) at 230 days post-BMT; there was no sign of graft-versus-host disease. Chimeric recipients (Lewis) permanently accepted (>200 days) donor (BN)-specific (RT11, n = 6) hind limbs, yet rapidly rejected (20 +/- 2 days) third-party hind limbs (Wistar Furth [WF]). Lymphocytes of graft-tolerant animals demonstrated hyporesponsiveness in mixed lymphocyte cultures in a donor-specific manner. Tolerant graft histology showed no signs of acute and chronic rejection.

CONCLUSIONS

The immunosuppressant and CTLA4-Ig-based conditioning regimen with donor BMT produced mixed chimerism and induced partial donor-specific tolerance to hind limb allografts.

The epithelial basal lamina of the isolated colonic mucosa: scanning and transmission electron microscopy

The morphology of the rat colonic basement membrane was studied under control conditions and after induction of secretion by distension in the Ussing chamber. The basement membrane was visualized by removing the epithelium with the aid of Ca2+ chelation combined with vibration. Specimens with and without metallic coating were studied with SEM and TEM, respectively. The surface of the basement membrane in the surface region of the epithelium, i.e. between the mouths of the crypts, is rough. In contrast, the deeper parts of the crypts have a rather smooth basal lamina, which is finely pleated. Fenestrations of the basal lamina with a diameter of 0.5-1 microns were found frequently at the surface region, but less frequently in the crypts. Fenestrations with diameters larger than 2 microns were never observed. After the distension experiments and long-time incubation in vitro (5 h), the size of the fenestrations remained unchanged, however, their number increased compared to the controls.

Machine Learning in the Development of Adsorbents for Clean Energy Application and Greenhouse Gas Capture

Addressing climate change challenges by reducing greenhouse gas levels requires innovative adsorbent materials for clean energy applications. Recent progress in machine learning has stimulated technological breakthroughs in the discovery, design, and deployment of materials with potential for high-performance and low-cost clean energy applications. This review summarizes basic machine learning methods-data collection, featurization, model generation, and model evaluation-and reviews their use in the development of robust adsorbent materials. Key case studies are provided where these methods are used to accelerate adsorbent materials design and discovery, optimize synthesis conditions, and understand complex feature-property relationships. The review provides a concise resource for researchers wishing to use machine learning methods to rapidly develop effective adsorbent materials with a positive impact on the environment.