High Production Capacity Research Articles

A System Dynamics Model for Capacity Planning of Component Supply in Complex Product Manufacturing

Complex product manufacturing faces a great challenge in coordinating the supply of components. Manufacturers of complex products are highly sensitive to supply chain delays as insufficient delivery of any components would suspend the entire assembly line. This article focuses on the capacity planning decisions of the supplier and manufacturer for coordinating the component supply of complex product manufacturing. A system dynamics model is developed to capture the dynamic interaction of supplier's production capacity planning and manufacturer's component inventory expansion capacity planning. Based on simulation results and analysis, the following guidelines are proposed for making capacity planning policies: 1) Information sharing should be advanced to help the manufacturer and supplier make capacity planning policies; 2) With only limited information about supplier's production capacity, it may not be favorable for the manufacturer to coordinate component supply by acquiring replenishment from backup suppliers; and 3) With only limited information about manufacturer's component inventory expansion capacity, it is better for the supplier to keep a higher production capacity.

Single-gene regulated non-spore-forming Bacillus subtilis: Construction, transcriptome responses, and applications for producing enzymes and surfactin

Bacillus subtilis, a spore-forming industrial bacterium, is widely used for production of enzymes and valuable chemicals. The spore-formation, however, always results in remarkably reduced cell-density, thereby reducing product yield. Here, we constructed different non-spore-forming B. subtilis mutants via single-gene regulation. During the three spore-forming stages: signal sensing, transduction, and sporulation, we found that deleting only a single gene of sporulation, i.e. spo0A, spoIIIE, and spoIVB, can completely block the spore generation. Interestingly, the engineered non-sporulating mutants exhibited physiological heterogeneity and distinct synthetic capabilities. The spo0A-null spore-free mutant displayed remarkably high enzyme production capacity, such as 194% enhance amylase production. However, the spoIVB-null non-spore-forming mutant was especially efficient in producing secondary metabolites, such as surfactin; its flask titer increased significantly to 16.7 g/L, with the overexpression and Leu addition strategy. Our results offer a new strategy for re-modeling B. subtilis to further improve its fermentation efficiency and application.

Extraction of Indole-3-acetic Acid from Plant Growth Promoting Rhizobacteria of Bamboo Rhizosphere and Its Effect on Biosynthesis of Chlorophyll in Bamboo Seedlings

Background: Indole-3-acetic acid (IAA), a principal phytohormone, controls several crucial physiological processes of plants. It ameliorates plant growth by stimulating cell elongation, root initiation, seed germination and seedling growth. Alteration of IAA level by plant growth promoting rhizobacteria leads to varied impacts on plant growth and development. Methods: Soil samples were collected from bamboo (Bambusa tulda, B. nutans subsp. cupulata, B. balcooa and Dendrocalamus strictus) rhizosphere. Altogether five bacterial isolates were screened by serial dilution method and subjected to biochemical analysis. The isolate BUX1 with high IAA production capacity was optimized for IAA production. IAA was partially purified and quantified from the bacterial extract by thin layer chromatography (TLC). The influence of extracted bacterial IAA on chlorophyll biosynthesis in bamboo seedlings of B. tulda was compared with uninoculated control plants. Results: Biochemical analysis revealed that all the isolates belonged to genus Bacillus which were found capable of producing IAA. During optimization, BUX1 isolate produced 99.13 µg ml-1 of IAA at 37°C, pH 7, 3 mg l-1 concentration of L-tryptophan and 150 rpm agitation rate after 192 hour of incubation. The Rf value of the bacterial IAA during TLC was identical to that of standard IAA (0.425) indicating that IAA was present in crude extract of Bacillus (BUX1). The influence of bacterial IAA on chlorophyll biosynthesis in bamboo seedlings was significant in comparison to uninoculated plants. Therefore, this isolate could be a prospective candidate to be employed as biofertilizer.

UTILIZATION OF LACTIC ACID RICH MEDIUM AND CASSAVA STARCH WASTEWATER FOR BIOLOGICAL HYDROGEN PRODUCTION

H2 production from lactic acid rich medium and H2 production from cassava starch wastewater by isolated bacteria were investigated. The isolation of H2 producing bacteria from heat treated sludge was carried out. The H2 production from lactic acid rich medium which used 1.5 g/L sodium acetate, 1.5 g/L sodium lactate and 1 g/L sucrose as carbon sources. The effects of inoculums size of 10, 20, 30 and 40 % (v/v) and incubation temperature of 35, 45 and 55oC using cassava starch wastewater as the substrate on H2 production by isolation strains were investigated. Results showed 6 isolated strains i.e. isolation code of MK01to MK06 indicated the H2 production capability when cultured in lactic acid rich medium. However, 3 isolated strains i.e. MK01, MK04, and MK06 were preferred to use as seed inoculums for further experiments depend on a high H2 production capacity obtained. Results indicated that the optimal condition of H2 production from cassava starch wastewater was 30% (v/v) inoculum size of MK06 under 35oC of incubation temperature. The maximum H2 production potential, H2 yield and H2 production rate of 4.20 L H2/L medium, 1.47 L H2/g substrate consumed, and 14.00 mL H2/L/h was obtained. Identification and characterization of MK06 were investigated using 16S rRNA gene sequence analysis followed by phylogenetic analysis. The 100% similarity of 16S rDNA compare with closely related species was indicated Klebsiella pneumoniae subsp. pneumoniae DSM 30104(T).

Bioremediation potential of new cadmium, chromium, and nickel-resistant bacteria isolated from tropical agricultural soil

Soil management using fertilizers can modify soil chemical, biochemical and biological properties, including the concentration of trace-elements as cadmium (Cd), chromium (Cd) and nickel (Ni). Bacterial isolates from Cd, Cr, and Ni-contaminated soil were evaluated for some characteristics for their use in bioremediation. Isolates (592) were obtained from soil samples (19) of three areas used in three maize cultivation systems: no-tillage and conventional tillage with the application of mineral fertilizers; minimum tillage with the application of sewage sludge. Four isolates were resistant to Cr3+ (3.06 mmol dm−3) and Cd2+ (2.92 mmol dm−3). One isolate was resistant to the three metals at 0.95 mmol dm−3. All isolates developed in a medium of Cd2+, Cr3+ and Ni2+ at 0.5 mmol dm−3, and removed Cd2+ (17–33%) and Cr6+ (60–70%). They were identified by sequencing of the gene 16S rRNA, as bacteria of the genera Paenibacillus, Burkholderia, Ensifer, and two Cupriavidus. One of the Cupriavidus isolate was able to remove 60% of Cr6+ from the culture medium and showed high indole acetic acid production capacity. We evaluated it in a microbe-plant system that could potentially be deployed in bioremediation by removing toxic metals from contaminated soil.

Random epigenetic modulation of CHO cells by repeated knockdown of DNA methyltransferases increases population diversity and enables sorting of cells with higher production capacities.

Chinese hamster ovary (CHO) cells produce a large share of today's biopharmaceuticals. Still, the generation of satisfactory producer cell lines is a tedious undertaking. Recently, it was found that CHO cells, when exposed to new environmental conditions, modify their epigenome, suggesting that cells adapt their gene expression pattern to handle new challenges. The major aim of the present study was to employ artificially induced, random changes in the DNA‐methylation pattern of CHO cells to diversify cell populations and consequently increase the finding of cell lines with improved cellular characteristics. To achieve this, DNA methyltransferases and/or the ten‐eleven translocation enzymes were downregulated by RNA interference over a time span of ∼16 days. Methylation analysis of the resulting cell pools revealed that the knockdown of DNA methyltransferases was highly effective in randomly demethylating the genome. The same approach, when applied to stable CHO producer cells resulted in (a) an increased productivity diversity in the cell population, and (b) a higher number of outliers within the population, which resulted in higher specific productivity and titer in the sorted cells. These findings suggest that epigenetics play a previously underestimated, but actually important role in defining the overall cellular behavior of production clones.

Development of Oil and Gas Projects Based on the Cluster Approach on the Example of the Irkutsk Oil Company

Currently, world experience in oil and gas production shows that long-term economic impact of the industry can only be achieved if high value-added production capacity is established. The article analyzed the role of oil and gas industry worldwide and in Russia, noting relatively low level of hydrocarbon processing in Russia. The article analyzed international experience of various forms of state participation in creation and support of oil and gas clusters. Main trends in the development of gas and chemical industry abroad have been identified. We analyzed the current strategy for the development of chemical and petrochemical complex up to 2030. The conclusion is made about the need for state support for large-scale projects to create clusters in the field of oil and gas production and refining. The article described main stages of the project to create an oil and gas cluster in the Irkutsk Region - a gas project of the Irkutsk Oil Company.

Directions of eliminating threats to the socio-economic development of regions

Subject. I devise a system approach to identifying and evaluating threats in ensuring the economic security of regions. Objectives. The study focuses on threats to the socio-economic development of regions in difficult geopolitical situations and determines how they can be eliminated. IT is important to determine key threats to the socio-economic development and the way they can be eliminated regionally. Methods. The article employs the multilevel and integrated approaches, a set of methods, such as systems, comparative and structural analyses, road mapping. Results. The article sets forth a road map for eliminating threats to the socio-economic development of regions, metrics to monitor the current situation and identify threats. I analyzed the socio-economic development of regions in the Ural Federal District and pinpointed the main threats. I conducted the comparative analysis of indicators to monitor the socio-economic development of regions, illustrative the cases of the Russian Federation, Ural Federal District, Sverdlovsk Oblast for 2018 year-on-year. The Ural Federal District and Sverdlovsk Oblast were found to exceed Russia’s average indicators in terms of directions of eliminating threats. It is indicative of opportunities to effectively employ the high production capacity of the old industrial region. Conclusions and Relevance. To settle directions of the socio-economic development of regions, economic agents should consider the elimination of threats, such as the new industrialization, comprehensive integration of innovation throughout economic sectors, import substitution, integration of production and social sector. The findings can be used by constituent entities of the Russian Federation to comprehensively assess the socio-economic development of regions, discover the main threats, and choose what should be done to eliminate them.

Limitations of Inclusive Agribusiness in Contributing to Food and Nutrition Security in a Smallholder Community. A Case of Mango Initiative in Makueni County, Kenya

Food and nutrition security remain at the top of development priorities in low income countries. This is especially the case for smallholder farmers who derive their livelihood from agriculture yet are often the most deprived. Inclusive agribusinesses have been championed as a key strategy to address local constraints that limit smallholders’ participation in regional and global value chains, thereby enhancing their livelihood, and food and nutrition security, accordingly. In this paper, based on a mixed method research approach, we explore the potential food and security contribution of inclusive agribusiness in Makueni county, Kenya. We focus on the smallholders’ constraints and needs, exploring the extent to which these are addressed by such purported pro-poor approach. First, using independent sample t-tests and a probit regression model, we explore who are able to participate in an ongoing intervention. We compare how participants and non-participants differ in terms of key socio-economic characteristics and establish which of these attributes are associated with successful integration into the business. Second, we again use independent sample t-tests to determine how the participants and non-participants compare in terms of their food and nutrition security. The household food and nutrition security is assessed with the conventional measurement tools: the household food insecurity access scale and the household food dietary diversity score. We find that participation in the inclusive agribusiness favors smallholder households with relatively higher production capacity in terms of better physical capital (land and number of mango trees, financial capital), access to loans, and human capital (age, education, and family size). Following income improvement, the participants’ household food security situation is significantly better than for non-participants. However, participation does not improve household dietary diversity, implying that improvement in income does not necessarily lead to better household nutrition security. To address the limitations of inclusive agribusiness, we propose policymakers and development actors to critically explore the contextual background prior to intervention design and implementation, and accordingly devise a broader approach for more inclusivity of the very poor and marginalized, and better food and nutrition security outcomes as a result. Given that not every smallholder could benefit from inclusive agribusiness for their food needs due to resource scarcity, alternative livelihood supports, including social protection programs and safety net plans, should be considered.

Application stages and nitrogen sources in topdressing of super-early bean crop irrigated

Producing food in a sustainable manner, exploiting the genetic potential of crops and optimizing cultivation time to ensure increased production are the biggest challenges for agriculture. The cultivation of super-early common bean lineages with high productive capacity leads to minor water consumption in crops under irrigation and vacate the area in less time. The objective of this work was to evaluate the yield components of super-early cycle common bean cultivars, under irrigated system in function of sources of nitrogen (N) as well as to assess different application stages. The experiment was conducted in randomized block design in a factorial scheme 4x3 + 1, corresponding of four sources of N in coverage (urea, urea + ammonium sulfate, urea + ammonium sulfate + elemental sulfur and urea + elemental sulfur), three application stages (V3, V4 and R5) and a control treatment. The N incorporation did not influence on the grain yield of the super-early cycle common bean regardless of the source and season, whereas significant results were merely found when compared to the control. The number of pods was affected when the application was carried out at the R5 stage, with a significant reduction in this yield component. The relative chlorophyll index was lower when nitrogen coverage was performed at the R5 stage.

Influx of diverse, drug resistant and transmissible Plasmodium falciparum into a malaria-free setting in Qatar

BackgroundSuccessful control programs have impeded local malaria transmission in almost all Gulf Cooperation Council (GCC) countries: Qatar, Bahrain, Kuwait, Oman, the United Arab Emirates (UAE) and Saudi Arabia. Nevertheless, a prodigious influx of imported malaria via migrant workers sustains the threat of local transmission. Here we examine the origin of imported malaria in Qatar, assess genetic diversity and the prevalence of drug resistance genes in imported Plasmodium falciparum, and finally, address the potential for the reintroduction of local transmission.MethodsThis study examined imported malaria cases reported in Qatar, between 2013 and 2016. We focused on P. falciparum infections and estimated both total parasite and gametocyte density, using qPCR and qRT-PCR, respectively. We also examined ten neutral microsatellites and four genes associated with drug resistance, Pfmrp1, Pfcrt, Pfmdr1, and Pfkelch13, to assess the genetic diversity of imported P. falciparum strains, and the potential for propagating drug resistance genotypes respectively.ResultsThe majority of imported malaria cases were P. vivax, while P. falciparum and mixed species infections (P. falciparum / P. vivax) were less frequent. The primary origin of P. vivax infection was the Indian subcontinent, while P. falciparum was mostly presented by African expatriates. Imported P. falciparum strains were highly diverse, carrying multiple genotypes, and infections also presented with early- and late-stage gametocytes. We observed a high prevalence of mutations implicated in drug resistance among these strains, including novel SNPs in Pfkelch13.ConclusionsThe influx of genetically diverse P. falciparum, with multiple drug resistance markers and a high capacity for gametocyte production, represents a threat for the reestablishment of drug-resistant malaria into GCC countries. This scenario highlights the impact of mass international migration on the reintroduction of malaria to areas with absent or limited local transmission.

Atmospheric dimethyl sulfide and its significant influence on the sea-to-air flux calculation over the Southern Ocean

Our understanding about the atmospheric dimethyl sulfide (DMS) and its influence to sea-to-air flux calculation in the Southern Ocean is still limited due to insufficient investigations. Herein, high-resolution shipboard underway simultaneous surface seawater and atmospheric DMS measurements were conducted in the Southern Ocean from February 23 to March 31, 2018. A larger variation of DMS levels was found in atmosphere compared with that in seawater. Remarkably, a large-scale area with high seawater and atmospheric DMS concentrations up to 27.9 nM and 3.92 ppbv, respectively, was investigated outside of Ross Sea sector. Atmospheric DMS levels were strongly impacted by wind speed and air mass convection. The relationship between atmospheric DMS and air mass exposure to oceanic chlorophyll varied greatly depending on the area of investigation. Some other regions with high DMS production capacity were examined as well beside those along the cruise tracks based on the results of positive correlations with high slopes and back trajectories. Moreover, significant uncertainty of sea-to-air DMS flux over the Southern Ocean could be caused by follows: (1) the selecting of different gas transfer coefficients; (2) the negative flux values calculated under high atmospheric DMS levels together with low seawater DMS concentrations; and (3) the greatly overestimated flux, approximately 47.1–76.9%, without considering the atmospheric DMS. This study highlights the urgent demand of high-resolution observations of atmospheric DMS over the Southern Ocean to estimate DMS emission with high accuracy.

Echinicola soli sp. nov., isolated from alkaline saline soil.

Strains of Echinicola, thought to play vital roles in the environment for their high enzyme production capacity during decomposition of polysaccharides, are ubiquitous in hypersaline environments. A Gram-negative, non-spore forming, gliding, aerobic bacterial strain, designated LN3S3T, was isolated from alkaline saline soil sampled in Tumd Right Banner, Inner Mongolia, northern PR China. Strain LN3S3T grew at 10-40 °C (optimum, 30 °C), pH 5.0-9.0 (optimum, pH 8.0) and with 0-12.5 % NaCl (optimum, 2.0 %). A phylogenetic tree based on the 16S rRNA gene sequences showed that strain LN3S3T clustered with Echinicola rosea JL3085T and Echinicola strongylocentroti MEBiC08714T, sharing 97.0, 96.7 and <96.50 % of 16S rRNA gene sequence similarities to E. rosea JL3085T, E. strongylocentroti MEBiC08714T and all other type strains. MK-7 was the major respiratory quinone, while phosphatidylethanolamine, two unidentified phospholipids, an unidentified aminophospholipid, an unidentified lipid and two unidentified aminolipids were the major polar lipids. Its major cellular fatty acids were iso-C15 : 0, anteiso-C15 : 0 and summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c). The genome consisted of a circular 5 550 304 bp long chromosome with a DNA G+C content of 44.0 mol%. The average nucleotide identity (ANI), average amino acid identity (AAI) and digital DNA-DNA hybridization (dDDH) values of strain LN3S3T to E. rosea JL3085T and E. strongylocentroti MEBiC08714T were 82.5 and 81.5 %, 87.5 and 86.0 %, and 39.1 and 35.1 %, respectively. Based on physiological, genotypic and phylogenetic analyses, strain LN3S3T could be discriminated from its phylogenetic relatives. Echinicola soli sp. nov. is therefore proposed with strain LN3S3T (=CGMCC 1.17081T=KCTC 72458T) as the type strain.

Effects of seedling age on the growth stage and yield formation of hydroponically grown long-mat rice seedlings

Understanding the characteristics of rice productivity is of great importance for achieving high yield formation. However, such traits have not yet been studied for different ages of hydroponically grown long-mat rice seedlings (HLMS), which constitutes a new method of seedling cultivation. Field experiments were conducted to evaluate the effects of seedling age on the growth stage, photosynthesis characteristics, dry matter production, and yield of HLMS. A conventional japonica rice cultivar (Wuyunjing 24) and an indica hybrid rice cultivar (6 Liangyou 9368) were used as test materials. The results showed that the whole phase was shortened by 13–15 days for young seedlings (13-day-old) compared with old seedlings (27-day-old), which occurred because the growth process accelerated with the transplantation of young seedlings. As seedling age increased, the dry matter weight of stems of individual plants and of the population increased at the transplanting stage but decreased at the maturity stage (MS). Compared with that of 27-day-old seedlings, the average ratio of panicle weight to total plant dry weight of 13-day-old seedlings during a 2-year period increased by 3.71% for Wuyunjing 24 and by 3.78% for 6 Liangyou 9368 at the MS. Moreover, as seedling age increased, the leaf area index and photosynthetic potential decreased for both cultivars, and the photosynthetic rate markedly decreased at the heading stage (HS). With the exception of that of Wuyunjing 24 from the jointing stage to the HS in 2014, the crop growth rate was higher for young seedlings than for old seedlings. Grain yield significantly decreased with seedling age, but no significant difference was detected between the 13- and 20-day-old seedlings for either cultivar. Therefore, equilibrious and high biological yield formation, vigorous growth in the late stages, and high photosynthetic production capacity are important characteristics and causes of the efficient and sustainable output of photosynthetic systems and for achieving high yield formation in young transplanted seedlings (13–20-day-old).

Design of Area and Power Efficient Multiplier Unit using Wallace T ree Algorithm

In any processing system, the core data path element may be a multiplier that particularly associated with DSP applications, which concludes overall processing unit performance. In such system, the multiplier unit improves the performance will boost up the potential. The Cadence EDA performs for high-speed multiplier evaluation consisting 64 x 64 bit in ASIC Digital flow (RTL-GDSII). Using carry select adder and carry save adder, the proposed multiplier intend with Wallace structure for enhancing the speed criteria. Wallace rebate absorbs more time for designing because it is more complex and aberrant in format for better width. Real Time signal processor requires high productive capacity and fewer reaction time. A classic scheme could be today in IOT utilizations. The proposed method concentrates on designing low power and area efficient in digital flow using the Wallace tree algorithm. The 180 nm CMOS technology for pursuance and outcome are related with other existing methods in delay, area and dynamic power dissipation.

Boosting the Performance of Alkanes’ Dehydrogenation Catalysts in the Industrial Scale by Altering the Water Injection Strategy

Water addition plays a pivotal role in prolonging the catalytic dehydrogenation reactions and normally starts at the beginning of the dehydrogenation process. A delayed water injection strategy is proposed in this study to improve the performance of bimetallic Pt-Sn/Al2O3 catalyst utilized for long-chain alkanes (nC10–C13) dehydrogenation in the industrial scale. The dehydrogenation reactions took place at a pressure of 0.11–0.13 MPa and temperature varied between 470 and 490 °C. Postponing the water supply until the middle of run leads to longer operating life for the catalyst and consequently reduces the production costs significantly. In addition, it promotes the quality of the final product by decreasing the undesired by-products and results in higher production capacities (by 1.5 %) in the industrial scale. Characterization of the deactivated dehydrogenation catalysts using different methods allows the understanding of the boosted performance of the catalyst arising from postponing the water injection process. Moreover, the proposed strategy reduces the waste production by decreasing the ratio of loaded catalyst to the desired product (by 23 %) and thus alleviates the negative environmental impact of the process. Furthermore, it results in lower energy consumption and promotes the mitigation of CO2 gas emissions by 3 % which can be effective in tackling environmental challenges in the large scale.

SME financing with new credit guarantee contracts over the business cycle

Two new credit guarantee contracts, called option-for-guarantee swaps (OGSs) and equity-for-guarantee swaps (EGSs), have become the important financial innovations/instruments over the past decade in China’s credit guarantee market and provide small and medium-sized enterprises (SMEs) with stable finance. In this paper we introduce a competitive credit guarantee market along with these two new financial contracts in a classical contingent claims model to analyze SME financing and investment and the incentives that these instruments create for entrepreneurs over the business cycle. We compare the main effects produced by OGSs and EGSs. The model based on our calibration of parameters predicts that financing through an EGS entails a higher market leverage ratio and a higher production capacity and, thus, a higher ex ante firm value than an otherwise identical firm financed with an OGS. We also show that, overall, EGS financing is effective at reducing the asset substitution incentive, while OGSs reduce the debt overhang problem. These findings offer a possible explanation for why these two new credit guarantee contracts are adopted by entrepreneurs in China’s credit guarantee market, and the optimal choice between OGSs and EGSs depends on priorities (attenuate the asset substitution incentive, reduce the debt overhang problem, or enhance value).

Continuous crystallization as a downstream processing step of pharmaceutical proteins: A review

Continuous crystallization has been proposed as the downstream processing step for the purification of pharmaceutical proteins aimed at alleviating the manufacturing bottleneck caused by the limitations of chromatography-based operations at high upstream production titers. Herein we reviewed the current state of research in continuous protein crystallization from which future research directions were identified. While the benefits of batch-to-continuous manufacturing transformation have been long established, progress in continuous protein crystallization lags behind its small-molecule counterpart. The reasons are because the challenging nature of protein crystallization, even when performed in the batch platform, and the lack of well-understood proteins available for thorough study. Nevertheless, successful batch-to-continuous transformations in both mixed-suspension-mixed-product-removal crystallizer and tubular crystallizers (i.e. slug flow, oscillatory baffled flow) have been demonstrated using lysozyme or monoclonal antibody as the model protein. Compared to the batch platform, the continuous platform produces comparable crystallization yield but with higher production capacity (g/h). Strategies to optimize the crystallizer's performance based on modeling and simulation results are also available. Future research should (1) study a wider range of proteins with impurities incorporated in the raw material streams, and (2) adopt advancements in continuous crystallization of small-molecule pharmaceuticals to improve the crystal quality and yield.

NIR-Driven Water Splitting H2 Production Nanoplatform for H2-Mediated Cascade-Amplifying Synergetic Cancer Therapy.

As a newly emerging treatment strategy for many diseases, hydrogen therapy has attracted a lot of attention because of its excellent biosafety. However, the high diffusivity and low solubility of hydrogen make it difficult to accumulate in local lesions. Herein, we develop a H2 self-generation nanoplatform by in situ water splitting driven by near-infrared (NIR) laser. In this work, core-shell nanoparticles (CSNPs) of NaGdF4:Yb,Tm/g-C3N4/Cu3P (UCC) nanocomposites as core encapsulated with zeolitic imidazolate framework-8 (ZIF-8) modified with folic acid as shell are designed and synthesized. Due to the acid-responsive ZIF-8 shell, enhanced permeability and retention (EPR) effect, and folate receptor-mediated endocytosis, CSNPs are selectively captured by tumor cells. Upon 980 nm laser irradiation, CSNPs exhibit a high production capacity of H2 and active oxygen species (ROS), as well as an appropriate photothermal conversion temperature. Furthermore, rising temperature increases the Fenton reaction rate of Cu(I) with H2O2 and strengthens the curative effect of chemodynamic therapy (CDT). The excess glutathione (GSH) in tumor microenvironment (TME) can deplete positive holes produced in the valence band of g-C3N4 in the g-C3N4/Cu3P Z-scheme heterojunction. GSH also can reduce Cu(II) to Cu(I), ensuring a continuous Fenton reaction. Thus, a NIR-driven H2 production nanoplatform is constructed for H2-mediated cascade-amplifying multimodal synergetic therapy.

Predicting Spinel Disorder and Its Effect on Oxygen Transport Kinetics in Hercynite.

The iron aluminate spinel hercynite (FeAl2O4) is a promising redox material for solar thermochemical hydrogen production (STCH). Although it has a high H2 production capacity, the kinetics of its oxidation and reduction may be too slow to be practical for STCH. However, our results suggest that Fe-rich hercynite may have substantially faster redox kinetics, which could make hercynite competitive with other materials for STCH. We used density functional theory to investigate the origin of hercynite's slow kinetic behavior and show that it arises from the high activation barrier of 2.46 eV for oxygen vacancy (VO) diffusion in normal hercynite. To model the effect of disorder caused by spinel inversion, we examined 11 of the most common cation arrangements and found a near 1:1 correlation between the diffusion barrier and VO formation energy, both of which decrease by 0.6 eV for each additional nearest-neighbor Fe atom. To examine this trend, we used integrated crystal orbital Hamilton population (ICOHP) analysis to estimate the difference in the metal-oxygen bond strengths of cations neighboring VO and the diffusion transition state. The ICOHP predicted bond strengths correlate to both the diffusion barrier and VO formation energy. We also computed the effect of the charge state of the oxygen vacancy and found that positively charged vacancies are stable at low Fermi energies and have a diffusion barrier of only 0.79 eV, 1.67 eV lower than that of the neutral vacancy, demonstrating that stabilizing these charged vacancies may enable faster oxidation and reduction kinetics in hercynite. We show that uncompensated Fe antisite defects, which are present in Fe-rich hercynite, provide redox flexibility that stabilizes the charged VO and thereby increase the rate of VO diffusion. Finally, we predict that at higher VO concentrations the diffusion barrier depends on the relative positions of the vacancies and decreases when they are next-nearest neighbors.