bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance Evaluation of Drip Irrigation Systems on Production of Okra (Hibiscus esculentus) in Southwestern, Nigeria
Authors: Amoo M. O. , Ademiju T. A. , Adesigbin A. J. , Ali G. A.
Published: October 2019

This study was carried out to evaluate the performance of drip irrigation systems on the production of okra (Hibiscus esculentus) in southwestern, Nigeria. Application of water to crops in an area of scarcity of water is very important to meet the food demand of the ever-increasing population and modified irrigation techniques that can assist the okra farmers to have affordable irrigation systems that will get them great yields at the end of the season was evaluated in this paper. A field experiment was conducted at the Teaching and Research farm of Agricultural and Bio-Environmental Engineering Department, School of Engineering Technology, The Federal Polytechnic, Ado, Ekiti - State, Nigeria. The field area of 150 mby 400 m was properly cleared, stumped, ploughed and harrowed. The topography of the land was flat with its suitable soil structure, texture, retention capacity and loamy clay soil. The cultivated area of land was divided into three and on each experimental plot, high yield and disease resistant okra variety seeds obtained from a research institute (IITA) were carefully selected and planted at a regular interval of 0.6 m. Drip laterals were laid in between rows of okra plants with inline drippers at a spacing of 20 cm. The parameters measured include okra seed germination, plant height, stem girth, number of leaves and yield production. The study also includes soil properties, crop water requirement and crop water use efficiency. There were no significant difference in the okra agronomic parameters at each experimental plots under drip irrigation system. The water applied to crop was greater than the actual crop water requirement and the efficiency of the drip irrigation was 68.5%.  There is high in seed germination percentage in with 3.5%, 3.6% and 3.8% at each experimental plot respectively. The selected okra agronomic parameters showed that okra performed very well under drip irrigation systems. Based on the results, water application through drip irrigation has a positive impact on growth and vegetative development of okra.
Analysis and Evaluation of Specific Absorption Rate of GSM Signal in Port Harcourt, Nigeria
Authors: Elechi Promise , Orike Sunny , Agugharam Promise
Published: October 2019

There is a growing concern in the world that residents close to GSM base station facilities are exposed to electromagnetic radiation which causes different health illness like cancer, leukemia, memory lost, dizziness, fatigue, etc. This study puts to rest the position on the effect of radiofrequency (RF) radiation from GSM masts on human health. In this research work, the evaluation and assessment of radio frequency radiation in five selected mobile base stations facilities in Obio/Akpor Local Government of Rivers State, Nigeria were carried out using an EMF meter for measurement of Electric field. The measurements of the radio frequency radiation with the EMF meter was conducted from 0 – 300m away from the selected base transceivers stations facilities of the selected telecommunication operators (MTN, Globacom and Airtel) in Nigeria. The data obtained from the research were analyzed using Specific Absorption Rate formula to establish whether with time exposure to RF radiation will have negative impact on human health. The normal specific absorption rate (SAR) and the Power Density for the general public whole body was assessed from the measured electric field strength and the results were compared with that of International Commission on Non Ionization Radiation Protection (ICNIRP).The results showed that the average amount of SAR for the selected five base transceiver station (BTS) facilities were within the range of 0.0037 W/kg – 0.0084 W/kg and the power density 1.5183 W/m2 – 9.5083 W/m2. These values are lower than the recommended limit by ICNIRP which is 0.08w/kg for the human body. This study has shown that there is inconsequential effect on human health because the non-ionizing electromagnetic energy has no sufficient energy to affect any part of human body for the residents living close to the selected BTS facilities of the various telecommunication providers.
A Study of Vacuum Efficiency for Silicon on Insulator Wafers
Authors: Bacquian Bryan Christian S. , Gomez Frederick Ray I.
Published: October 2019

The development on thinner packages has become the trend and focus in semiconductor packaging industry. The necessity of thinner packages also entails a thinner vertical structure of the integrated circuit (IC) design. As a major contributor on the vertical structure of the IC package, die or wafer is also essential to go thinner. As the wafer goes thinner, various problems may occur during transport and even the back grinding process, itself.

Wafer warpage is one of the main concerns during the process. The effect of proper vacuuming will play major role in processing SOI wafers. Insufficient vacuum may cause non-planar wafer in contact with the chuck table that may result to poorer grinding and worst broken wafer. 

Different silicon wafer technology has been released to cater different functionality on different industry markets. One popular silicon technology is Silicon On Insulator (SOI) technology. SOI wafers have a step type passivation wherein the edge of the wafer is observed to have 30um thinner than its center. The stepping effect also contributes to the 0.5mm wafer warpage prior back grinding. Evaluating the effect of vacuum efficiency to eliminate such warpage is discussed on this technical paper.
Effectiveness of Various Techniques Using FRP for the Strengthening of R. C. Beams with Tension Lap Splices
Authors: Makhlouf Mohamed H.
Published: October 2019

This paper presents an experimental program conducted to investigate the flexural performance of RC beams with tension reinforcement lap splice strengthened using externally bonded FRP different techniques in splice region. The specimens were reinforced on the tension side with four deformed bars spliced at mid span. The tested beams are of 3200 mm total length and 250*120 mm cross section, tested in positive bending. The considered parameters were splice length, type of FRP (glass or carbon), strengthening techniques in splice region (externally confine strips around cross section, Near Surface Mounted technique "NSM" stirrups, externally bonded sheets or bars on the tension face, number of GFRP strips layers (one layer, two layers, and three layers), and shape of NSM stirrups (Box or U shape). No additional anchorage mechanism or bonding methodology was applied for the FRP strips on the concrete except the epoxy adhesive. The effect of these factors on the failure of modes, the ultimate load, the bond strength and that the ductility were investigated. The results indicated that all applied strengthening techniques were efficient in improving the bond strength of the lap splices, the ductility, and the load-deflection behavior of the tested beams, especially when strips were installed over the splice region. This study approved that NSM technique gave more prominent simplicity of employ.
Comparative Study of Weekly Discharge Rate of Two Solar Batteries Commonly Used in Anambra State
Authors: Marymartha Ugbaja, Chikodiri , Ikeh C. U. , Egwuonwu G. N.
Published: October 2019

The purpose of this study is to compare the weekly discharge rate of two solar batteries commonly used in Anambra State. The batteries considered were the Indian made battery with specification Luminous, Deep cycle sealed maintenance free batteries solar application, Lum 12V 100Ah 20hr and 3DGP161433 and Chinese made battery with specification Sun-Test std gel battery, 12V-100Ah, 010716w, Cycle use 14.4-15.0V, Stand by use; 13.5-13.8V and Initial current: less than 30A were used to power 2 stand-alone security lights at the Faculty of Physical Sciences, Nnamdi Azikiwe University, Awka. The technical assessment was based on measuring their output voltages bihourly from 19.00 hr to 7.00 hr and estimation of weekly discharge rate of these batteries for a period of two months (eight weeks). From the analysis, the Indian made solar battery has insignificant discharge tendency for the first eight weeks of its use having its discharge rate of -0.034, -0.038, -0.042, -0.037, -0.039, -0.038, -0.039 and -0.036 Volts/hr per week from week one to week eight respectively whereas the Chinese made solar battery has a relatively high discharge rate of Voltage/hr per week within the first eight weeks of its use having its rate at  -0.095, -0.213, -0.103, -0.1, -0.104, -0.1, -0.083 and -0.109Volt/hr per week from week one to week eight. Also, while the Indian made battery is observed to be relatively stable, the Chinese made battery was observed to be very erratic and highly susceptible to discharge within the first eight weeks (two months) of its use. Hence, it is concluded that Indian made battery is preferred to that of Chinese made battery for optimal performance of stand-alone PV syste.
A Numerical Study of the Induced Stresses in the Separation Points of the Tensile Element (Chain) of the Plate Conveyor Used in the Blowing Unit in Water Factories
Authors: Khalil Ethar , Youssef Hiba , Nazha Hasan
Published: October 2019

The Induced Stresses in Tensile Element Joints (chain) were Studied in Two Phases: The first phase is to conduct a design study of the plate conveyor to determine the maximum tensile strength to which the joint is exposed. Then build two models, the first one represents a single joint with its components (wedge- copper ring- plate) with the basic dimensions and measurements of the chain. The second model was designed with new dimensions to suit the conveyor's working conditions. In the second phase, the three-dimension finite elements method was used to identify the stresses induced in the joint for both models and then compare the results to identify the model that shows the best performance. The result showed that increasing the external thickness of the joint by double in the proposed model up to the value of 6 mm was able to provide a homogeneous distribution of the main induced stress, which contributed to reducing the critical values of these stresses compared to the induced stresses in the model currently used. Consequently, increasing the external thickness of the joint has played an important role in reducing stresses, which leads to an increase the service life of the plate conveyor chain.
Prediction and Optimization of Production Quantities in Innoson Manufacturing Extraction Plastic Product
Authors: Daniel Ezeliora, Chukwuemeka , Chukwuma Okoye, Peter , Ikenna U. Mbabuike,
Published: October 2019

In this research, it focused on the prediction and optimization of the production quantity in Innoson Plastic Manufacturing Company, Nnewi, Anambra State, Nigeria. The research method used is the application of factorial design methods to model, to evaluate the best optimal solutions for the production quantity of extrusion plastic pipes in the aforementioned company. The analysis shows that the parameters used to model the production quantity are significant and the model produced is also significant with its coefficient of determination to be 0.9968 and the adjusted R-Squared is 0.9823. Adequate Precision measures the signal to noise ratio. A ratio greater than 4 is desirable. The ratio of 29.271 indicates an adequate signal. This model can be used to navigate the design space. The Model F-value of 68.99 implies the model is significant. There is only a 1.44% chance that an F-value this large could occur due to noise. Values of "Prob > F" less than 0.0500 indicate model terms are significant. The 3D surface plot shows the effect of the variables in production system. It describes the variations of the input and output parameters in production of plastic extrusion products. The factorial design method applied shows the optimal solution which revealed that the best quantity of the product that is necessary to produce in any given month is 14414.112 units of a 25mm diameter plastic pipes with the optimal desirability of 100%. The tool also shows that the pigment is almost not important in the optimization of the product production quantity due to its insignificant quantity. However, the results further revealed that the industry should be conscious of highly influence input variable during production.
Friction Coefficients of Local Food Grains on Different Structural Surfaces
Authors: Nwakuba N. R. , Chukwuezie O. C. , Uzoigwe F. C. , Chukwu P.
Published: October 2019

Knowledge of friction coefficient of agricultural commodities on various structural surfaces is imperative in the design and material selection for postharvest handling, transportation, processing and storage equipment. This paper presents the friction coefficients of local food grains on different structural surfaces as a function of moisture content. The experiment was conducted using a Complete Randomized Design (CRD) in a factorial treatment design to evaluate the influence of different structural surfaces (glass, mild steel, plastic, ply-board, and aluminium) and moisture content levels (6, 12, 18, and 24% wet basis) on the coefficient of friction of selected local grains (benniseed, finger millet, pearl millet, and hungry rice). Results obtained indicate that the friction coefficient (μ) of the studied grain samples increased linearly with increase in moisture level for all the tested structural surfaces. Within the range of the studied moisture content, benniseed exhibited the highest μ-value (0.526 ± 0.031 ≤ μ ≤ 0.784 ± 0.157) on ply-board, whereas hungry rice had the lowest value (0.248 ± 0.018 ≤ μ ≤ 0.527 ± 0.023) on glass material. Amongst the tested metal surfaces, aluminum had the lowest μ-value (0.236) at 6% moisture content. The effect of structural surfaces and moisture contents as well as their interactions on friction coefficient were statistically significant at P =.05 for all the studied grain samples. High values of correlation coefficient (R2) > 0.95 were obtained to indicate strong correlation between μ-values and experimental factors. A low coefficient of variation (CV) of 2.75% was obtained to show high experimental reliability.
A Critical Analysis of Multi-Regime Fundamental Equations
Authors: Akweittey Emmanuel , Fosu Gabriel O.
Published: October 2019

Aims/ Objectives: Multi-regime fundamental models use two or more equations to describe the association among the main maroscopic traffic variables encountered in traffic analysis. The paper investigates specific properties of some multi-phase speed-density equations. 

Methodology: It first compares the characteristics of each of these equations by solving the nonlinear continuity traffic equation. 

Results: It was observed that predicting vehicular trajectories with these model equations could lead to misinformation. The kinematic wave and stable shockwave properties of these models were also ascertained. 

Conclusion: Based on the results, it was concluded that it would be more cumbersome to explain nonlinear traffic characteristics when these two and three regime models are adopted.
Analyzing and Eliminating Die Passivation Crack in a Power Leadframe Package using Submodeling Approach
Authors: Talledo Jefferson
Published: October 2019

This paper presents the submodeling approach in thermo-mechanical simulation of the die passivation crack encountered in a power leadframe package subjected to temperature cycling condition.  Without using modeling and simulation in resolving semiconductor package development issues, the process would be very costly and time-consuming. For die passivation crack, the details of the different layers of the die passivation need to be modeled and this would result in a large simulation model with considerable solution time. However, a technique known as submodeling can be used to reduce solution time without sacrificing accuracy of results. In this study, submodeling was successfully used to analyze the stresses in the critical passivation layer that resulted in the best design that eliminated the passivation crack. The modeling result showed that the crack could be eliminated by using the right passivation material layer combination and thickness. An increase in the thickness of the material layers and the additional of sublayers have provided significant stress reduction in the topmost critical passivation layer resulting in crack elimination.
Improving the Solder Joint Reliability of a Power Leadframe Package Using Thermomechanical Simulation
Authors: Talledo Jefferson
Published: October 2019

Leadframe-based packages are commonly used for semiconductor power devices. With these packages, heat dissipation is much better compared with laminate substrated-based packages. However, the solder joint reliability requirement under thermal cycling condition is also higher and this is what makes the development of a power package challenging. One of the usual requirements from customers is that there should be no solder joint failure up to 2,000 thermal cycles. This paper presents the thermomechanical simulation of a power leadframe package that was conducted to improve its solder joint reliability. Board level solder joint cycle life was predicted using finite element analysis and the result was validated with actual solder life result from board level reliability evaluation. Since available solder prediction equation was for the characteristic life (63.2% accumulative failure), using the normalized characteristic life was implemented for predicting the number of cycles to first failure of the solder joint connection and the approach showed good agreement with the actual result. Results also indicated that the choice of epoxy mold material and the type of PCB (printed circuit board) have a significant contribution to the solder joint reliability performance.
Wirebond Solution of Semiconductor IC Package through Modeling and Simulation
Authors: Gomez Frederick Ray I. , Moreno Anthony R. , Pulido Jonathan C.
Published: October 2019

This technical paper presents a study of wirebond selection highlighting the package electrical modeling and simulation done for semiconductor integrated circuit (IC) leadframe package (hereinafter referred to as Device Z) with different wirebond configurations: Gold 2N 1.3 mil, Gold 4N 1.3 mil, Copper 1.3 mil, Copper 1.2 mil, Copper 1.1 mil and Copper 1.0 mil.  Package design, modeling and simulation are essentially important in the early stage of the package development, particularly at the package feasibility phase. 

As Device Z is previously assembled with Gold 4N 1.3 mil wirebond configuration, this technical paper focused in determining the best alternative for Gold 4N 1.3 mil in wirebonding through package modeling and simulation. Statistical analysis reinforced the study to verify the trend and to check if there is significant statistical difference in the resistance, inductance and capacitance (hereinafter referred to as RLC) performance of the device given the different wirebond configurations.  Cost analysis was crucial to determine the cost impact of using different wires.

Prioritizing the wirebond thickness and cost without sacrificing the electrical performance, Copper 1.1 mil would be the most suitable replacement for Gold 4N 1.3 mil wirebond configuration.  However, since Copper 1.1 mil is not yet available in the market, Copper 1.2 mil could be used, with better electrical parameters. In addition, Copper wire offered significant cost improvement over its Gold counterpart. Computed cost per unit of Copper 1.3 mil is just 6% of the total cost of the Gold 4N 1.3 mil – that is 94% cost savings. Ultimately, Copper wire technology offers significant cost savings and could pave the way for more businesses in the plant.
Chaos Control of a Resource-Economic-Pollution Dynamic System
Authors: Yin Jiuli , Huang Jing , Fan Xinghua
Published: October 2019

How to control chaos in the economic system has aroused the interest of researchers. We research the chaos control in a new Resource-Economic-Pollution system by time-delayed feedback control. By determining the appropriate range of time delay τ and feedback strength k, the chaotic phenomena of the system are controlled. We verify the linear stability and the existence of Hopf bifurcation of the system. Numerical simulations show that chaos control can eliminate the chaotic behavior of the system and stabilize the system at the equilibrium point. When the time lag term is in a certain interval, the chaotic phenomenon of the system will disappear and the system will be controlled in a stable state. In practice, due to capacity and financial constraints, the firm or the government often restrains output through many methods to confine the range of fluctuations in these variables. This shows that the government or corporate decision makers have often used this approach consciously or unconsciously to promote steady economic growth.
Improvement of Final Settling Tanks Performance by Using Chemical Additions
Authors: Halawa Mohamed A. E. , Fouad Hanan A. , Elhefny Rehab M. , Wail A. F.
Published: October 2019

Biological treatment in wastewater treatment plants WWTPs consists of two main tanks, aeration tank and final settling tank. Aeration process using in return activated sludge system is very costly and it is required to operate WWTPs with low dissolved oxygen (DO) concentration in aeration process without risking poor effluent quality. To apply this study, a plant model for the addition of chemicals must be made with the necessary calibration of this model. Laboratory experiments were started between November 2017 and June 2018. This paper will discuss the impact of DO concentration on sludge properties by using a pilot plant model WWTP and find the optimum doses of Hydrogen peroxide H2O2 concentration with using low DO concentration to achieve good sedimentation.  In this study the DO set-point was changed every 3 weeks between 0.5 mg/l and 4.5 mg/l for a few months.  Experiments were carried out to The optimal ratio and dosage of H2O2 /Fe+2 was 5 as 30/6 mg/l. BOD, COD, TSS and VSS removal efficiency by using H2O2 /Fe+2 were 91%, 89% 90% & 89%, respectively with DO = 1.5 mg/l at an increased rates were 21.3%, 25.4%, 20% & 12.7%, respectively. Results of paper proves that the addition of optimum H2O2 will save 2 mg/l of DO concentration and providing a high cost of using electricity and mechanical equipment compared to the non-use of H2O2.
NCS‐1 expression is higher in basal breast cancers and regulates calcium influx and cytotoxic responses to doxorubicin
Authors: Bong Alice H. L. , Robitaille Mélanie , Milevskiy Michael J. G. , Roberts‐Thomson Sarah J. , Monteith Gregory R.
Published: October 2019

Neuronal calcium sensor‐1 (NCS‐1) is a positive modulator of IP3 receptors and was recently associated with poorer survival in breast cancers. However, the association between NCS‐1 and breast cancer molecular subtypes and the effects of NCS‐1 silencing on calcium (Ca2+) signaling in breast cancer cells remain unexplored. Herein, we report for the first time an increased expression of NCS‐1 in breast cancers of the basal molecular subtype, a subtype associated with poor prognosis. Using MDA‐MB‐231 basal breast cancer cells expressing the GCaMP6m Ca2+ indicator, we showed that NCS‐1 silencing did not result in major changes in cytosolic free Ca2+ increases as a result of endoplasmic reticulum Ca2+ store mobilization. However, NCS‐1 silencing suppressed unstimulated basal Ca2+ influx. NCS‐1 silencing in MDA‐MB‐231 cells also promoted necrotic cell death induced by the chemotherapeutic drug doxorubicin (1 µm). The effect of NCS‐1 silencing on cell death was phenocopied by silencing of ORAI1, a Ca2+ store‐operated Ca2+ channel that maintains Ca2+ levels in the endoplasmic reticulum Ca2+ store and whose expression was significantly positively correlated with NCS‐1 in clinical breast cancer samples. This newly identified association between NCS‐1 and basal breast cancers, together with the identification of the role of NCS‐1 in the regulation of the effects of doxorubicin in MDA‐MB‐231 breast cancer cells, suggests that NCS‐1 and/or pathways regulated by NCS‐1 may be important in the treatment of basal breast cancers in women.
A Periodic Deformation Mechanism of a Soft Actuator for Crawling and Grasping
Authors: Li Zhengjie , Huang Rong , Liu Zishun
Published: October 2019

Periodic locomotion in nature has provided many inspirations for soft actuators. Compared with rigid actuators, soft actuators can transform into versatile shapes to adapt to different working environments and are able to interact with the human in a safer manner because of their compliance. However, soft actuators often suffer from complex structures designs and complicated sequences of stimuli to achieve periodic locomotion. To overcome this shortcoming, a periodic deformation mechanism based on strain energy storing is proposed in this paper. Guided by this mechanism, a simple soft actuator is designed without complicated control systems. The soft actuator involves shape memory alloy and silicon rubber. Crawling and grasping of the soft actuator are achieved by electrical heating methods. The proposed mechanism can provide inspiration for the design of soft actuators, smart wearable equipment, and medical devices.
Millisecond‐Timescale, High‐Efficiency Modulation of Upconversion Luminescence by Photochemically Derived Graphene
Authors: Lamon Simone , Wu Yiming , Zhang Qiming , Liu Xiaogang , Gu Min
Published: October 2019

The millisecond‐timescale, high‐efficiency modulation of upconversion luminescence via ultraviolet laser‐induced photochemical reduction of graphene oxide is reported. The luminescence tuning is achieved by combining a thin film of graphene oxide with lanthanide‐doped upconversion nanoparticles. The recovery of the graphene‐like structure through the photochemical reduction of graphene oxide is accompanied by a variation in the absorption coefficient of the as‐synthesized nanocomposite, which enables super‐quenching of the luminescence emission from the upconversion nanoparticles under near‐infrared laser excitation with values of up to ≈90%. Further, the instantaneous reduction in the emission intensity upon ultraviolet laser irradiation allows a 106‐fold decrease of the time for fast modulation of upconversion luminescence from up to tens of minutes down to milliseconds at microwatt‐level laser power. Optical patterning is successfully produced in the nanocomposite and individual pixels are retrieved distinctly with high spatial resolution through upconversion luminescence emission quenching by reduced graphene oxide. This method offers a superior avenue for controlling upconversion luminescence with high contrast, fast reaction speed, and low power consumption.
Formation of Polarized, Functional Artificial Cells from Compartmentalized Droplet Networks and Nanomaterials, Using One‐Step, Dual‐Material 3D‐Printed Microfluidics
Authors: Li Jin , Baxani Divesh Kamal , Jamieson William David , Xu Wen , Rocha Victoria Garcia , Barrow David Anthony , Castell Oliver Kieran
Published: October 2019

The bottom‐up construction of synthetic cells with user‐defined chemical organization holds considerable promise in the creation of bioinspired materials. Complex emulsions, droplet networks, and nested vesicles all represent platforms for the engineering of segregated chemistries with controlled communication, analogous to biological cells. Microfluidic manufacture of such droplet‐based materials typically results in radial or axisymmetric structures. In contrast, biological cells frequently display chemical polarity or gradients, which enable the determination of directionality, and inform higher‐order interactions. Here, a dual‐material, 3D‐printing methodology to produce microfluidic architectures that enable the construction of functional, asymmetric, hierarchical, emulsion‐based artificial cellular chassis is developed. These materials incorporate droplet networks, lipid membranes, and nanoparticle components. Microfluidic 3D‐channel arrangements enable symmetry‐breaking and the spatial patterning of droplet hierarchies. This approach can produce internal gradients and hemispherically patterned, multilayered shells alongside chemical compartmentalization. Such organization enables incorporation of organic and inorganic components, including lipid bilayers, within the same entity. In this way, functional polarization, that imparts individual and collective directionality on the resulting artificial cells, is demonstrated. This approach enables exploitation of polarity and asymmetry, in conjunction with compartmentalized and networked chemistry, in single and higher‐order organized structures, thereby increasing the palette of functionality in artificial cellular materials.
Visible Light–Driven Cascade Carbon–Carbon Bond Scission for Organic Transformations and Plastics Recycling
Authors: Gazi Sarifuddin , Đokić Miloš , Chin Kek Foo , Ng Pei Rou , Soo Han Sen
Published: October 2019

Significant efforts are devoted to developing artificial photosynthetic systems to produce fuels and chemicals in order to cope with the exacerbating energy and environmental crises in the world now. Nonetheless, the large‐scale reactions that are the focus of the artificial photosynthesis community, such as water splitting, are thus far not economically viable, owing to the existing, cheaper alternatives to the gaseous hydrogen and oxygen products. As a potential substitute for water oxidation, here, a unique, visible light–driven oxygenation of carboncarbon bonds for the selective transformation of 32 unactivated alcohols, mediated by a vanadium photocatalyst under ambient, atmospheric conditions is presented. Furthermore, since the initial alcohol products remain as substrates, an unprecedented photodriven cascade carboncarbon bond cleavage of macromolecules can be performed. Accordingly, hydroxyl‐terminated polymers such as polyethylene glycol, its block co‐polymer with polycaprolactone, and even the non‐biodegradable polyethylene can be repurposed into fuels and chemical feedstocks, such as formic acid and methyl formate. Thus, a distinctive approach is presented to integrate the benefits of photoredox catalysis into environmental remediation and artificial photosynthesis.
Manganese exposure, parkinsonian signs, and quality of life in South African mine workers
Authors: Dlamini Wendy W. , Nelson Gill , Nielsen Susan Searles , Racette Brad A.
Published: October 2019

Background

Manganese (Mn) neurotoxicity is associated with parkinsonism; the associated motor deficits can affect individuals’ quality of life (QoL). We investigated associations between Mn exposure, parkinsonian signs, and QoL in Mn mine workers.

Methods

We assessed parkinsonian signs and QoL in 187 black South African Mn mine workers, using the Unified Parkinson Disease Rating Scale motor subsection 3 (UPDRS3) and the Parkinson Disease Questionnaire (PDQ‐39), respectively. We estimated cumulative Mn exposure in mg Mn/m3‐years using complete occupational histories and a job‐exposure matrix. We investigated the cross‐sectional association between cumulative Mn exposure and UPDRS3 score, and the UPDRS3 score and PDQ‐39, adjusting for age, using linear regression.

Results

Participants’ mean age was 41.8 years (range, 21‐67 years); 97.3% were male. Estimated mean cumulative Mn exposure at the time of examination was 5.4 mg Mn/m3‐years, with a mean of 14.0 years working in a Mn mine. The mean UPDRS3 score was 10.1 and 25.7% of the workers had a UPDRS3 score greater than or equal to 15. There was a U‐shaped dose‐response relation between cumulative Mn exposure and UPDRS3 score, with a positive association up to 15 mg Mn/m3‐years of exposure and an inverse association thereafter. Greater UPDRS3 scores were associated with poorer self‐reported QoL.

Conclusion

In this cohort of employed Mn mine workers, parkinsonian signs were common and were associated with both estimated cumulative Mn exposure and poorer QoL.
Selected Topics in the Syntheses of Bicyclo[1.1.1]Pentane (BCP) Analogues
Authors: Ma Xiaoshen , Nhat Pham Luu
Published: October 2019

This Minireview focuses on selected topics in the syntheses of bicyclo[1.1.1]pentane (BCP) analogues. A brief historical introduction was included. The content covers various synthetic routes of 1‐substituted and 1,3‐disubstituted BCPs. Selective examples of synthetically useful building blocks are summarized for each category for synthetic organic chemists’ and medicinal chemists’ reference. A compare‐and‐contrast analysis is also applied to evaluate these routes and to demonstrate the progress of strategic functional group transformations using modern organic methodologies. By systematically analyzing the synthetic strategies to access these strained molecules, we also hope that this Minireview will provide inspirations for future developments in this area.
The half‐sandwich titanocene CpTiIIICl2 as efficient system for the preparation of 2,5‐dihydrofurans via α‐allenols
Authors: Torres‐García Irene , López‐Martínez Josefa L. , Martínez‐Martínez Raquel , Oltra J. Enrique , Muñoz‐Dorado Manuel , Rodríguez‐García Ignacio , Álvarez‐Corral Miriam
Published: October 2019

The half‐sandwich titanocene reagent CpTiIIICl2, obtained by in situ reduction of commercial CpTiCl3 with manganese, is an excellent system for the Barbier‐type reaction between aldehydes and propargylic halides, leading to homopropargylic alcohols and α‐allenols. An efficient and straightforward methodology for the conversion of aldehydes into 2,5‐dihydrofurans involving a two‐step sequence (TiIII addition‐AgI cyclization) is presented. The usefulness of the method is proved by the preparation of a Natural Product: a dihydrofuranic labdane, isolated from the leaves of Mikania sp. nov.
Big impacts from small abstractions: The effects of surface water abstraction on freshwater fish assemblages
Authors: Boddy Nixie C. , Fraley Kevin M. , Warburton Helen J. , Jellyman Phillip G. , Booker Doug J. , Kelly Dave , McIntosh Angus R.
Published: October 2019

Abstractions and diversions are prevalent in river networks worldwide; however, specific mechanisms and measures reflecting changes in functional characteristics of aquatic assemblages in response to flow abstraction have not been well established. In particular, the influence of small takes on fish assemblages is poorly understood.

Field surveys and stable‐isotope analyses were used to evaluate the impact of differing levels of flow abstraction on fish assemblage structure, and native–non‐native patterns of coexistence, associated with small surface water abstractions in four streams in New Zealand. Study design accounted for longitudinal processes (spatial autocorrelation) to isolate the effects of abstractions on fish assemblages.

Reaches with reduced flows downstream of abstraction points had significantly lower fish abundances per metre of stream length, probably because of decreased habitat size, altered interspecific interactions and barriers to movement. The loss of larger fish in reaches with high abstraction resulted in shallower mass–abundance slopes and shorter stable isotope‐derived food‐chain lengths, likely to have been caused by fewer trophic links in the food web. The large fish absent from these reaches were flow‐sensitive introduced salmonids, resulting in higher relative abundances of small‐bodied native fish, probably as a result of predatory and competitive release.

Quantification of metrics designed to characterize ecosystem functioning as well as abundance and species composition indicated that small water abstractions can alter both the structure and composition of stream fish assemblages and modify the outcomes of native–non‐native species interactions. Thus, a better understanding of the effects of small abstractions could be used to improve the strategic management of fish in invaded riverscapes.
Intergenerational Transmission of Diet‐Induced Obesity, Metabolic Imbalance, and Osteoarthritis in Mice
Authors: Harasymowicz Natalia S. , Choi Yun‐Rak , Wu Chia‐Lung , Iannucci Leanne , Tang Ruhang , Guilak Farshid
Published: October 2019

Objective

Obesity and osteoarthritis (OA) are 2 major public health issues affecting millions of people worldwide. Whereas parental obesity affects the predisposition to diseases such as cancer or diabetes in children, transgenerational influences on musculoskeletal conditions such as OA are poorly understood. This study was undertaken to assess the intergenerational effects of a parental/grandparental high‐fat diet on the metabolic and skeletal phenotype, systemic inflammation, and predisposition to OA in 2 generations of offspring in mice.

Methods

Metabolic phenotype and predisposition to OA were investigated in the first and second (F1 and F2) generations of offspring (n = 10–16 mice per sex per diet) bred from mice fed a high‐fat diet (HFD) or a low‐fat control diet. OA was induced by destabilizing the medial meniscus. OA, synovitis, and adipose tissue inflammation were determined histologically, while bone changes were measured using micro–computed tomography. Serum and synovial cytokines were measured by multiplex assay.

Results

Parental high‐fat feeding showed an intergenerational effect, with inheritance of increased weight gain (up to 19% in the F1 generation and 9% in F2), metabolic imbalance, and injury‐induced OA in at least 2 generations of mice, despite the fact that the offspring were fed the low‐fat diet. Strikingly, both F1 and F2 female mice showed an increased predisposition to injury‐induced OA (48% higher predisposition in F1 and 19% in F2 female mice fed the HFD) and developed bone microarchitectural changes that were attributable to parental and grandparental high‐fat feeding.

Conclusion

The results of this study reveal a detrimental effect of parental HFD and obesity on the musculoskeletal integrity of 2 generations of offspring, indicating the importance of further investigation of these effects. An improved understanding of the mechanisms involved in the transmissibility of diet‐induced changes through multiple generations may help in the development of future therapies that would target the effects of obesity on OA and related conditions.
Use of 6‐Methylisoxanthopterin, a Fluorescent Guanine Analog, to Probe Fob1‐Mediated Dynamics at the Stalling Fork Barrier DNA Sequences
Authors: Mariam Jessy , Krishnamoorthy G. , Anand Ruchi
Published: October 2019

Fluorescent nucleic acid base mimics serve as excellent site‐specific and real‐time reporters of the local and global dynamics. In this work, using the fluorescent guanine mimic 6‐methylisoxanthopterin (6‐MI), we unravel the differential dynamics of replication fork barrier/terminator sequences (RFB1 and RFB3) mediated by fork blocking protein (Fob1). By strategic and site‐specific incorporation of this probe, we show that 6‐MI is able to capture the changes in global dynamics exhibited by Fob1 and aids in distinguishing between varied architectural forms like double‐stranded DNA versus Holliday junctions (HJs). This is important as these barriers are hotspots for recombination. Fluorescence lifetime and anisotropy decay studies further revealed that Fob1 strongly dampens the dynamics in double‐stranded RFB1, and the sequence inherently possesses lesser flexibility in comparison to RFB3. We show that 6‐MI can probe the differential oligomeric status of Fob1 in response to various architectures, that is, double‐stranded versus HJs. This work highlights the unique advantages of 6‐MI as a probe when incorporated in nucleic acid frameworks.
Containment control of high‐order multi‐agent systems with heterogeneous uncertainties, dynamic leaders, and time delay
Authors: Parsa Mohsen , Danesh Mohammad
Published: October 2019

This paper deals with containment control of multi‐agent systems where high‐order canonical controllable linear systems with heterogeneous uncertainties are considered as the agents' dynamics. The leaders are dynamic with polynomial‐type trajectories. In this paper, the control protocol is smooth and it is constructed from a flexible combination of local state feedback controller and a PI‐type protocol. Utilizing this protocol, containment without suffering from chattering phenomena and consideration of any bound on the agents' states is achieved. In addition, the flexibility of this protocol helps the designer to reduce or even discard the inter‐agent communication. Recalling the significant effects of time delay on the performance and stability of multi‐agent systems, in this paper input time delay is also considered. Following a Lyapunov‐Krasovskii stability approach, two linear matrix inequalities (LMIs) are derived, and then solving the LMIs' gains of the protocol are attained such that asymptotic stability of the multi‐agent system under switching graph topology is guaranteed. Finally, the feasibility of the LMIs and the validity of the theoretical results are demonstrated through some numerical examples.
Co−Ni Binary‐Metal Oxide Coated with Porous Carbon Derived from Metal‐Organic Framework as Host of Nano‐Sulfur for Lithium‐Sulfur Batteries
Authors: Zhang Xuan , Fan Yu , Khan Muhammad Arif , Zhao Hongbin , Ye Daixin , Wang Jiulin , Yue Baohua , Fang Jianhui , Xu Jiaqiang , Zhang Lei , Zhang Jiujun
Published: October 2019

Lithium‐sulfur battery is considered as a promising energy storage system because of its high energy density. The specific capacity and cycling stability of sulfur cathode, however, are impeded by intrinsic poor electrical conductivity of sulfur and dissolution of polysulfides intermediates. Herein, we demonstrate a novel strategy to overcome the two obstacles by designing a bimetallic‐organic‐framework‐derived nano‐sulfur host consisted of porous graphitic carbon and bimetallic cobalt‐nickel oxides (C/NiCo2O4), in which porous carbon and NiCo2O4 not only entrapping the polysulfides effectively through physical and chemical entrapment capability, but also serving as a highly conductive matrix for sulfur. With a sulfur content of 68.9 % in the composite, the composite cathode delivered a specific capacity of 977 mAh g−1 and maintained 673 mAh g−1 at 0.5 C over 500 cycles. Besides, the binding mechanism between NiCo2O4 and polysulfides has been explored by ex situ XRD and density functional theory(DFT)simulation. This work may provide a feasible strategy to improve the performance of lithium‐sulfur battery.
Synthesis of Camphecene and Cytisine Conjugates Using Click Chemistry Methodology and Study of Their Antiviral Activity
Authors: Artyushin Oleg. I. , Moiseeva Aleksandra A. , Zarubaev Vladimir V. , Slita Aleksander V. , Galochkina Anastasiya V. , Muryleva Anna A. , Borisevich Sophia S. , Yarovaya Olga I. , Salakhutdinov Nariman F. , Brel Valery K.
Published: October 2019

A series of camphecene and quinolizidine alkaloid (−)‐cytisine conjugates has been obtained for the first time using ‘click’ chemistry methodology. The cytotoxicity and virus‐inhibiting activity of compounds were determined against MDCK cells and influenza virus A/Puerto Rico/8/34 (H1N1), correspondingly, in in vitro tests. Based on the results obtained, values of 50 % cytotoxic dose (CC50), 50 % inhibition dose (IC50) and selectivity index (SI) were determined for each compound. It has been shown that the antiviral activity is affected by the length and nature of linkers between cytisine and camphor units. Conjugate 13 ((1R,5S)‐3‐(6‐{4‐[(2‐{(E)‐[(1R,4R)‐1,7,7‐trimethylbicyclo[2.2.1]heptan‐2‐ylidene]amino}ethoxy)methyl]‐1H‐1,2,3‐triazol‐1‐yl}hexyl)‐1,2,3,4,5,6‐hexahydro‐8H‐1,5‐methanopyrido[1,2‐a][1,5]diazocin‐8‐one), which contains cytisine fragment separated from triazole ring by –C6H12– aliphatic linker, showed the highest activity at relatively low toxicity (CC50=168 μmol, IC50=8 μmol, SI=20). Its selectivity index appeared higher than that of reference compound, rimantadine. According to theoretical calculations, the antiviral activity of the lead compound 13 can be explained by its influence on the functioning of neuraminidase.
Effect of fermentation time on the nutritional properties of pea protein‐enriched flour fermented by Aspergillus oryzae and Aspergillus niger
Authors: Kumitch Hayley M. , Stone Andrea , Nosworthy Matthew G. , Nickerson Michael T. , House James D. , Korber Darren R. , Tanaka Takuji
Published: October 2019

Background and objectives

The overall goal of this research was to examine the effect of solid‐state fermentation using Aspergillus oryzae and Aspergillus niger over time on the nutritional properties of an air‐classified pea protein‐enriched flour (PPEF). Specifically, changes to levels of enzyme inhibitors, total phenolics, in vitro protein digestibility (IVPD), and protein quality (IVPD‐corrected amino acid score) were assessed.

Findings

Trypsin and chymotrypsin inhibitors were reduced by 11.6 and 30.4%, and 22.8 and 21.8% for A. niger and A. oryzae, respectively, whereas the total phenolic content increased by 35.3 and 44.7% for A. niger and A. oryzae, respectively. IVPD increased over the fermentation time. However, the overall protein quality as measured by the IVPD‐corrected amino acid score became worse, becoming lowered by 5%–15% after 6 hr.

Conclusions

SSF improved the digestibility and bioactive compound availability, whereas protein quality was not improved.

Significance and novelty

Findings indicate that this particular solid‐state fermentation system improved the digestibility of the PPEF.
Global Optimization of Adsorbate Covered Supported Cluster Catalysts: The Case of Pt7H10CH3 on α‐Al2O3
Authors: Zhai Huanchen , Sautet Philippe , Alexandrova Anastassia N.
Published: October 2019

Determining structures of supported sub‐nanometer catalytic clusters is important for finding binding sites, active sites, and reaction mechanisms. In realistic conditions, the cluster may be covered with adsorbed reactants and intermediates, which strongly affect the structure of the cluster compared to the low coverage regime. The global optimization of supported adsorbate‐covered clusters is not possible with existing methods. We present a customized Basin Hopping (BH) approach, with a core (metal cluster)‐shell (adsorbates) separation scheme, and perform first applications to the search of low‐energy isomers of Pt7/α‐Al2O3 at high hydrogen coverage (10H). The presence of adsorbates significantly alters the low‐energy isomers compared to bare Pt7/α‐Al2O3. Molecular dynamics simulations additionally show the different time‐scales associated with the mobility of H and Pt atoms. The revised BH method with core‐shell separation presents key advantages for the structural exploration of adsorbate‐covered supported catalysts, relevant to realistic catalytic conditions.
Design and synthesis of a stereodynamic catalyst with reversal of selectivity by enantioselective self‐inhibition
Authors: Scholtes Jan Felix , Trapp Oliver
Published: October 2019

Chirality plays a pivotal role in an uncountable number of biological processes, and nature has developed intriguing mechanisms to maintain this state of enantiopurity. The strive for a deeper understanding of the different elements that constitute such self‐sustaining systems on a molecular level has sparked great interest in the studies of autoinductive and amplifying enantioselective reactions. The design of these reactions remains highly challenging; however, the development of generally applicable principles promises to have a considerable impact on research of catalyst design and other adjacent fields in the future. Here, we report the realization of an autoinductive, enantioselective self‐inhibiting hydrogenation reaction. Development of a stereodynamic catalyst with chiral sensing abilities allowed for a chiral reaction product to interact with the catalyst and change its selectivity in order to suppress its formation, which caused a reversal of selectivity over time.