Product Distribution Research Articles

The construction of iron-based catalysts encapsulated by graphite for CO2 hydrogenation to light olefins

Developing efficient catalytic materials and unveiling the active factors are significant for selective hydrogenation of CO2 to light olefins (C2–4=). Herein, Fe3O4-FeCx nanoparticles coated by graphite without other doped elements were synthesized successfully. The optimal catalyst exhibited CO2 conversion of 48.0 %, C2–4= space–time yield of 29.0 mmol·g−1·h−1, and a stability of 100 h (3.0 MPa, 320 °C, and GHSV = 12000 mL·g−1·h−1). The core–shell structure derived from the strong interaction between the phenolic hydroxyl group of resin and iron ions, as well as the encapsulation of the copolymer P123. The characterization results revealed that the size of core–shell particles and thickness of graphite layers could be regulated by P123, which affected the conversion of CO2 and products distribution significantly. Moreover, the combined results of quasi in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTs) and Raman spectra suggested small particle size and thin graphite shell strengthen the adsorption and conversion of CO2, playing an important role in the formation of light olefins. This work proposes a simple and feasible synthesis strategy to construct Fe3O4-FeCx particles encapsulated by graphite shell, which provides insights into catalysts design and the reaction mechanism of CO2 conversion to light olefins.

Effect of the charge asymmetry and orbital angular momentum in the entrance channel on the hindrance to complete fusion

The hindrance to complete fusion is studied as a function of the charge asymmetry of colliding nuclei and orbital angular momentum of the collision. The formation and evolution of a dinuclear system (DNS) in the heavy-ion collisions at energies near the Coulomb barrier is calculated in the framework of the DNS model. The DNS evolution is considered as nucleon transfer between its fragments. The results prove that a hindrance at formation of a compound nucleus (CN) is related with the quasifission process, which is breakup of the DNS into products instead to reach the equilibrated state of the CN. The role of the angular momentum in the charge (mass) distribution of the reaction products for the given mass asymmetry of the colliding nuclei has been demonstrated. The results of this work have been compared with the measured data for the quasifission yields in the C12+Pb204 and Ca48+Er168 reactions to show the role of the mass asymmetry of the entrance channel. Published by the American Physical Society 2024

Utilization of social franchising in family planning services: a Pakistan perspective

IntroductionPakistan's private sector caters to around 65% of family planning users. Private sector family planning was promoted in the Delivering Accelerated Family Planning in Pakistan (DAFPAK) program by UK's Foreign, Commonwealth & Development Office (FCDO) in 2019. We use data from DAFPAK to analyze the clientele and products distributed by two major NGOs, Marie Stopes Society (MSS) and DKT Pakistan, that support private providers in Pakistan. We also examined the effect of COVID-19 on client visits and contraceptives uptake at private facilities in Pakistan.MethodsDAFPAK used field validation surveys to analyze the volume of clients and products of 639 private facilities across three provinces (Punjab, KPK and Balochistan) of Pakistan. The data was collected in two phases (February 2020 and 2021) using multi-stage cluster sampling at 95% confidence level. Using a generalized negative binomial regression, facility-level characteristics and impact of COVID-19 was analyzed with the volume of clients and products given out at 95% confidence interval alongside descriptive analysis.ResultsDKT facilities covered 53% of the sample while MSS covered 47%, with 72% facilities in the rural areas. Average facility existence duration is 87 months (7.25 years). While the average experience of the facility staff is 52 months (4.33 years). MSS is serving more clients as compared to DKT during both phase 1 (IRR: 3.15; 95% CI: 2.74, 3.61) and phase 2 (IRR: 2.11; 95% CI: 1.79, 2.49). Similarly, MSS had a greater volume of products given out in both phases 1 (IRR: 1.89; 95% CI: 1.51, 2.38) and phase 2 (IRR: 2.57; 95% CI: 2.09, 3.14). In both phases, client visits and product distribution decreased when client privacy is invaded (IRR: 0.74; 95% CI: 0.67, 0.82 – phase 1) and (IRR: 0.83; 95% CI: 0.72, 0.97 – phase 2). Lastly, during COVID-19, products distribution decreased by a factor of 0.84 (IRR: 0.84; 95% CI: 0.72, 0.97) but client visits remain unaffected.ConclusionOverall, clientele is low for all facilities. At a facility, privacy is a determinant of client visits and products given out per visit. Transiently, during COVID-19, client volumes decreased, with a shift from oral pills to condoms and emergency contraceptive pills.

Time-resolved surface reaction kinetics in the pressure gap.

We extend the use of our recently developed Near-Ambient Pressure Velocity Map Imaging (NAP-VMI) technique to study the kinetics and dynamics of catalytic reactions in the pressure gap. As an example, we show that NAP-VMI combined with molecular beam surface scattering allows the direct measurement of time- and velocity-resolved kinetics of the scattering and oxidation of CO on the Pd(110) surface with oxygen pressures at the surface up to 1 × 10-5 mbar, where different metastable surface structures form. Our results show that the c(2 × 4) oxide structure formed at low O2 pressure is highly active for CO oxidation. The velocity distribution of the CO2 products shows the presence of two reaction channels, which we attribute to reactions starting from two distinct but rapidly interconverting CO binding sites. The effective CO oxidation reaction activation energy is Er = (1.0 ± 0.13) eV. The CO2 production is suppressed at higher O2 pressure due to the number of antiphase domain boundaries increasing, and the missing row sites are filled by O-atoms at O2 pressures approaching 1 × 10-6 mbar. Filling of these sites by O-atoms reduces the CO surface lifetime, meaning the surface oxide is inactive for CO oxidation. We briefly outline further developments planned for the NAP-VMI and its application to other types of experiments.

On the distribution of Sudler products and Birkhoff sums for the irrational rotation

On the distribution of Sudler products and Birkhoff sums for the irrational rotation

Modeling the influence of carbon branching structure on secondary organic aerosol formation via multiphase reactions of alkanes

Abstract. Branched alkanes represent a significant proportion of hydrocarbons emitted in urban environments. To accurately predict the secondary organic aerosol (SOA) budgets in urban environments, these branched alkanes should be considered as SOA precursors. However, the potential to form SOA from diverse branched alkanes under varying environmental conditions is currently not well understood. In this study, the Unified Partitioning Aerosol Phase Reaction (UNIPAR) model is extended to predict SOA formation via the multiphase reactions of various branched alkanes. Simulations with the UNIPAR model, which processes multiphase partitioning and aerosol-phase reactions to form SOA, require a product distribution predicted from an explicit gas kinetic mechanism, whose oxygenated products are applied to create a volatility- and reactivity-based αi species array. Due to a lack of practically applicable explicit gas mechanisms, the prediction of the product distributions of various branched alkanes was approached with an innovative method that considers carbon lengths and branching structures. The αi array of each branched alkane was primarily constructed using an existing αi array of the linear alkane with the nearest vapor pressure. Generally, the vapor pressures of branched alkanes and their oxidation products are lower than those of linear alkanes with the same carbon number. In addition, increasing the number of alkyl branches can also decrease the ability of alkanes to undergo autoxidation reactions that tend to form low-volatility products and significantly contribute to alkane SOA formation. To account for this, an autoxidation reduction factor, as a function of the degree and position of branching, was applied to the lumped groups that contain autoxidation products. The resulting product distributions were then applied to the UNIPAR model for predicting branched-alkane SOA formation. The simulated SOA mass was compared to SOA data generated under varying experimental conditions (i.e., NOx levels, seed conditions, and humidity) in an outdoor photochemical smog chamber. Branched-alkane SOA yields were significantly impacted by NOx levels but insignificantly impacted by seed conditions or humidity. The SOA formation from branched and linear alkanes in diesel fuel was simulated to understand the relative importance of branched and linear alkanes with a wide range of carbon numbers. Overall, branched alkanes accounted for a higher proportion of SOA mass than linear alkanes due to their higher contribution to diesel fuel.

Big data analytics for quality variation over work shifts in manufacturing systems

ABSTRACT In the manufacturing industry, mass production enables manufacturers to produce parts with high precision and lower costs. Multiple shifts operate production processes to maximize efficiency. Several researches have been conducted on the impact of shift work on labor’s health and habits. However, there have been few studies on the influence of shift work on the consistency of product quality. This paper provides a methodology to analyze the impact of different work shifts in a real electronic board manufacturing industry. The study uses big data and analytics to assess product quality from data. Non-parametric kernel density estimation is used to approximate the distribution of good products in each work slot. Then several metrics are used to measure the dissimilarity between the estimated densities. The approach can be leveraged in various problems related to process performance and quality. The obtained results show that there is no significant difference in terms of product quality between work shifts. These prove the consistency of the manufacturing processes and the homogeneity of performance across work shifts in the studied factory. Compared to the literature, the paper presents the first quantitative analysis to compare production process performance and product quality over shift works.

Control and surveillance of redox potential for 233Pa dissolution in 2LiF-BeF2 molten salt.

233Pa, the precursor nuclide of 233U in the thorium-uranium conversion is prone to reductive deposition in 2LiF-BeF2 (66 : 34 mol%, FLiBe) molten salt. We explored the adjustment and control of the redox potential of the FLiBe melt to avoid the 233Pa reduction deposition. The experimental data indicated that the deposited 233Pa can be completely dissolved and reentered into the molten salt with the addition of oxidant NiF2, and the distribution and behaviour of uranium, thorium, neptunium, and most fission products did not have any significant change in the NiF2-oxidised FLiBe molten salt, showing the feasibility of this manner to make 233Pa exist stably in the melt. The effects of NiF2-addition on the behaviour of the fission products 95Nb and 131I in the FLiBe molten salt were also investigated. It was found that 131I could be used as a redox indicator to monitor the redox potential of the oxidation-enhanced FLiBe molten salt. All the information drawn from this study could provide significant support for the control and surveillance of the redox potential of the FLiBe molten salt in the upcoming thorium molten salt reactor (TMSR).

Visualizing Electrochemical CO2 Conversion via the Emerging Scanning Electrochemical Microscope: Fundamentals, Applications and Perspectives.

With the rapid development and maturity of electrochemical CO2 conversion involving cathodic CO2 reduction reaction (CO2RR) and anodic oxygen evolution reaction (OER), conventional ex situ characterizations gradually fall behind in detecting real-time products distribution, tracking intermediates, and monitoring structural evolution, etc. Nevertheless, advanced in situ techniques, with intriguing merits like good reproducibility, facile operability, high sensitivity, and short response time, can realize in situ detection and recording of dynamic data, and observe materials structural evolution in real time. As an emerging visual technique, scanning electrochemical microscope (SECM) presents local electrochemical signals on various materials surface through capturing micro-current caused by reactants oxidation and reduction. Importantly, SECM holds particular potentials in visualizing reactive intermediates at active sites and obtaining instantaneous morphology evolution images to reveal the intrinsic reactivity of active sites. Therefore, this review focuses on SECM fundamentals and its specific applications toward CO2RR and OER, mainly including electrochemical behavior observation on local regions of various materials, target products and onset potentials identification in real-time, reaction pathways clarification, reaction kinetics exploration under steady-state conditions, electroactive materials screening and multi-techniques coupling for a joint utilization. This review undoubtedly provides a leading guidance to extend various SECM applications to other energy-related fields.

What can we learn when fitting a simple telegraph model to a complex gene expression model?

In experiments, the distributions of mRNA or protein numbers in single cells are often fitted to the random telegraph model which includes synthesis and decay of mRNA or protein, and switching of the gene between active and inactive states. While commonly used, this model does not describe how fluctuations are influenced by crucial biological mechanisms such as feedback regulation, non-exponential gene inactivation durations, and multiple gene activation pathways. Here we investigate the dynamical properties of four relatively complex gene expression models by fitting their steady-state mRNA or protein number distributions to the simple telegraph model. We show that despite the underlying complex biological mechanisms, the telegraph model with three effective parameters can accurately capture the steady-state gene product distributions, as well as the conditional distributions in the active gene state, of the complex models. Some effective parameters are reliable and can reflect realistic dynamic behaviors of the complex models, while others may deviate significantly from their real values in the complex models. The effective parameters can also be applied to characterize the capability for a complex model to exhibit multimodality. Using additional information such as single-cell data at multiple time points, we provide an effective method of distinguishing the complex models from the telegraph model. Furthermore, using measurements under varying experimental conditions, we show that fitting the mRNA or protein number distributions to the telegraph model may even reveal the underlying gene regulation mechanisms of the complex models. The effectiveness of these methods is confirmed by analysis of single-cell data for E. coli and mammalian cells. All these results are robust with respect to cooperative transcriptional regulation and extrinsic noise. In particular, we find that faster relaxation speed to the steady state results in more precise parameter inference under large extrinsic noise.

The effect of temperature on the co-combustion of hydrochar and NH3 using the ReaxFF method

The utilization of NH3, a carbon-free hydrogen carrier, can be optimized through its co-combustion with solids. However, prior studies have primarily focused on coal as the solid fuel, which entails its consumption. Considering that hydrochar possesses abundant oxygen-containing functional groups, as well as high mass and energy density, it presents itself as a promising alternative solid fuel to coal, thereby decreasing dependence on fossil fuels. Therefore, this study investigates the co-combustion of different proportions of hydrochar, NH3, and O2. Molecular dynamic simulations using the ReaxFF MD method were conducted to investigate the impact of temperature on combustion by analyzing product distribution, evolution of bonds, and gas characteristic curves. Additionally, N migration was examined to elucidate the processes leading to the generation of N2 and NOx from NH3. The results showed that temperature facilitated the progression of combustion as the total number of molecules increased (from 2614 at 2000 K to 3137 at 2500 K) and variety of products expanded (from 48 at 2000 K to 69 at 2500 K) with increasing temperature. With increasing temperature, the descent rate of NH3 and oxygen accelerated, whereas the quantities of H2 and H2O increased. Furthermore, during combustion, hydrochar underwent three stages: initial coke formation, subsequent tar generation, and organic gas production. Second, during N migration, hydrochar directly or indirectly participated in the formation of N2. In this process, hydrochar indirectly contributed to the formation of NH and NH2 intermediates, leading to the formation of N2. In contrast, the majority of NO was formed through the direct decomposition of hydrochar. Finally, because of the limited quantity of generated NO2, N existed primarily in the form of N2 and NO. These findings provide theoretical guidance for the combustion of NH3 using hydrochar.

Closing the Gap Between Gas Phase and Condensed Phase: Fragmentation Studies of the Thiomethoxymethyl Complex [(bipy)Pt(CH3)2(CH2SCH3)]+

AbstractCollision‐induced dissociation (CID) of the mass‐selected cation [(bipy)Pt(CH3)2(CH2SCH3)]+ in an ion‐trap mass‐spectrometer results in the losses of the neutrals ethane, ethene, dimethyl sulfide, methane, ethyl methyl sulfide, and propane. The generation of the first four neutrals is also observed, when the isolated, dimeric complex [(bipy)Pt(CH3)2(CH2SCH3)]2[SbF6]2 is heated in the condensed phase. While the product distribution is very similar regardless of whether the complex is heated in the solid state or in solution, ethane loss, i. e. the quite rare event of an sp3‐sp3 C−C reductive elimination from a platinum(IV) complex, dominates in the gas‐phase experiment. However, when the counter anion [SbF6]− is exchanged by the more weakly coordinating anion [BAr4F]−, the amounts of ethane and ethene are increased also in the condensed phase. These sum of observations indicates the similarities of the fragmentation of [(bipy)Pt(CH3)2(CH2SCH3)]+ in both phases. Thus, a correlation of processes in both environments is possible for selected systems (and particularly for unimolecular processes), but the choice of the proper conditions is crucial for a meaningful comparison.

PyQCAMS: Python Quasi-Classical Atom–Molecule Scattering

We present Python Quasi-classical atom–molecule scattering (PyQCAMS v0.1.0), a new Python package for atom–diatom scattering within the quasi-classical trajectory approach. The input consists of the mass, collision energy, impact parameter, and pair-wise/three-body interactions. As the output, the code provides the vibrational quenching, dissociation, and reactive cross sections along with the rovibrational energy distribution of the reaction products. We benchmark the program for a reaction involving a molecular ion in a high-density ultracold gas, RbBa+ + Rb. Furthermore, we treat H2 + Ca → CaH + H reactions as a prototypical example to illustrate the properties and performance of the software. Finally, we study the parallelization performance of the code by looking into the speedup of the program as a function of the number of CPUs used.

Co-liquefaction of α-cellulose and phycocyanin: A preliminary study

Hydrothermal liquefaction (HTL) is an efficient technology for converting biomass to platform compounds. It has great potential for reducing the dependence on fossil fuels. The HTL of waste biomass has been extensively studied in recent years due to both its environmental and economic benefits. However, most woody waste contains a large amount of cellulose, and it is difficult to be sufficiently decomposed to valuable chemicals. Phycocyanin, a key component of algae, is easily degraded under high-temperature liquefaction conditions. In this work, focusing on bio-oil generation properties, the co-liquefaction characteristics and synergistic mechanisms of α-cellulose and phycocyanin were explored. The findings revealed a maximum bio-oil yield of 33.1 wt% under the optimal conditions (300 °C for 40 min), with a notable positive synergistic effect of 13.5 wt%. Chemical composition analysis indicated distinct compositional differences between the bio-oils derived from individual and dual feedstock. The amounts of pyridine and pyrimidine compounds increased due to the enhanced co-liquefaction. The results also highlighted the influence of temperature on the degree of conversion and product distribution. Finally, preliminary chemical reaction pathway was elucidated, underscoring the potential of integrating microalgae and woody biomass for enhanced bio-oil production.

Deciphering complexity in Pd–catalyzed cross-couplings

Understanding complex reaction systems is critical in chemistry. While synthetic methods for selective formation of products are sought after, oftentimes it is the full reaction signature, i.e., complete profile of products/side-products, that informs mechanistic rationale and accelerates discovery chemistry. Here, we report a methodology using high-throughput experimentation and multivariate data analysis to examine the full signature of one of the most complicated chemical reactions catalyzed by palladium known in the chemical literature. A model Pd-catalyzed reaction was selected involving functionalization of 2-bromo-N-phenylbenzamide and multiple bond activation pathways. Principal component analysis, correspondence analysis and heatmaps with hierarchical clustering reveal the factors contributing to the variance in product distributions and show associations between solvents and reaction products. Using robust data from experiments performed with eight solvents, for four different reaction times at five different temperatures, we correlate side-products to a major dominant N-phenyl phenanthridinone product, and many other side products.

Determinants of Agribusiness Diversification Among Women Agri-Preneurs in Njoro and Molo Sub-Counties in Nakuru County, Kenya

Participating in agribusiness value chains is significant for growth and development of an economy. Women have been noted to have low participation in agribusiness activities as compared to men because women face challenges such as inaccessibility and ownership of assets, social cultural hindrances, lower market innovativeness and versatility factors. To reduce these challenges faced by women agri-preneurs, there is need to adopt agribusiness diversification to ensure the success of agribusiness enterprises. The aim of this study was to determine the factors that influence the number of agribusiness lines that female agri-preneurs participate in. This study was carried out in Njoro and Molo Sub-counties in Nakuru County, Kenya between March and August 2023. A standard Poisson regression model was carried out to examine the number of agribusiness lines that female agri-preneurs have to maximize revenue and spread risks associated with post production agribusiness activities such as selling, distribution and value addition of agricultural products. The study sampled 267 female in agribusinesses, both group participants and non-participants. Data processing was done using SPSS and STATA software. The results showed that age, education level, Leadership position, size of agribusiness enterprise, time taken in the agribusiness activities and ability of the female agri-preneurs to borrow loans positively influence the number of agribusiness lines that women agri-preneurs have.

Analysis of Marketing Mix Implementation on Purchasing Decisions for Skintific Skincare Products (Survey of the Community in Jabodetabek)

This research investigates the impact of marketing mix implementation on purchasing decisions for Skintific Skincare Products among consumers in the Jabodetabek region. A quantitative research design was employed, surveying 200 respondents to gather insights into consumer preferences, brand perceptions, pricing influences, and marketing mix synergies. Results indicate that product quality and competitive pricing emerged as significant determinants of consumer satisfaction, brand loyalty, and purchase intention. Furthermore, correlations between marketing mix elements such as product quality, pricing, distribution channels, and promotional activities underscored their collective influence on consumer behavior and brand positioning. The findings offer strategic recommendations for Skintific to enhance market performance, sustain competitive advantage, and drive long-term success in the skincare industry.

ANALISIS PEMASARAN OTAK-OTAK JUMBO IKAN TENGGIRI PADA UMKM PERMAI SARI KABUPATEN BANDUNG

Permai Sari’s MSME, which is located in the Kopo complex, is a micro, small and medium enterprise that sells products in the field of fish processing, namely grilled fish cake made from mackerel fish. Carrying out marketing analysis aims to find out how management and social processes occur in Permai Sari’s MSME. This research method uses a survey method. Sampling used purposive sampling. The data collected is primary data from interviews and secondary data taken from journals, books or other libraries. The results of this research show that the business of grilled fish cake made from mackerel fish obtained an added value of IDR 47,000/kg of raw material. With a profit of IDR 41,390/kg. Permai Sari's MSME competitors in terms of selling otak-otak products are street vendors who don't sell every day. Determining product prices uses cost-plus pricing which aims to make a profit. The promotional methods used are word of mouth and through applications on the internet. Distribution of otak-otak products by leaving them in stores and selling directly to consumers. Analysis of product production using forecasting methods.

Revealing the mechanism of Ce promoter in modulating product distribution of CO2 hydrogenation over Fe-based catalysts

This study elucidates the influence of the Ce promoter on the structure and surface intermediates of Fe-based catalysts and provides insights into the mechanism controlling the distribution of CO2 hydrogenation products. The product distribution revealed a volcano-shaped trend for the selectivity of light olefins and C5+ products as the Ce content increased from 0 to 10 wt%, whereas the selectivity for CH4 shows an inverted volcano-shaped trend. Concurrently, the selectivity for CO gradually increased from 14.4 % to 58.8 %. When the Ce content was 1 wt%, the selectivity for light olefins and C5+ products reached maximum values of 41.4 % and 19.1 %, respectively, and the selectivity for methane decreased to 34.3 %. Characterization by in situ X-ray diffraction (XRD), in situ infrared spectroscopy (IR), and X-ray photoelectron spectroscopy (XPS) techniques demonstrated that the variation in product distribution could be attributed to the altered ratio of Fe3O4 to Fe5C2 species, surface enrichment of the Na promoter, and generation and desorption of surface intermediate species induced by the Ce promoter. These factors affect the rate of the reverse water gas shift reaction (RWGS) and the subsequent Fischer-Tropsch (FT) reaction, thereby modulating the product distribution. Understanding the regulation mechanism of the CO2 hydrogenation product distribution by the Ce promoter is expected to provide valuable insights for guiding the design of catalyst structures.

Regulating Cu Oxidation State for Electrocatalytic CO2 Conversion into CO with Near-Unity Selectivity via Oxygen Spillover.

Cu-based catalysts are the most intensively studied in the field of electrocatalytic CO2 reduction reaction (CO2RR), demonstrating the capacity to yield diverse C1 and C2+ products albeit with unsatisfactory selectivity. Manipulation of the oxidation state of Cu sites during CO2RR process proves advantageous in modulating the selectivity of productions, but poses a formidable challenge. Here, an oxygen spillover strategy is proposed to enhance the oxidation state of Cu during CO2RR by incorporating the oxygen donor Sb2O4. The Cu-Sb bimetallic oxide catalyst attains a remarkable CO2-to-CO selectivity approaching unity, in stark contrast to the diverse product distribution observed with bare CuO. The exceptional Faradaic efficiency of CO can be maintained across a wide range of potential windows of ≈700mV in 1m KOH, and remains independent of the Cu/Sb ratio (ranging from 0.1:1 to 10:1). Correlative calculations and experimental results reveal that oxygen spillover from Sb2O4 to Cu sites maintains the relatively high valence state of Cu during CO2RR, which diminishes the binding strength of *CO, thereby achieving heightened selectivity in CO production. These findings propose the role of oxygen spillover in CO2RR over Cu-based catalysts, and shed light on the rational design of highly selective CO2 reduction catalysts.