Cut Area Research Articles

Utility Cut Impact Assessment and Fee Development Using Pavement Management System

The purpose of this study is to estimate any damage caused by utility cuts to pavements and develop a fee schedule to recover the costs associated with such damage using the City of Pacifica, CA, U.S.’s pavement management system (PMS). To accomplish this, the study looked at the functional deterioration of pavements resulting from utility cuts. The City of Pacifica’s PMS containing a vast dataset of pavement distress spanning 15 years, comprising thousands of data points encompassing various pavement ages and conditions, was analyzed to assess the impact of utility cuts. The findings from this study include: 1) Pavements with cuts of any size deteriorate more than pavements without cuts across all age groups with one exception for older residentials with small cuts; 2) On average, pavement condition index drops by 30% if the cut area is greater than 10% of the section area; and 3) Utility cuts inflict greater damage on newer pavements (<10 years old) compared with older ones (≥10 years old). Consequently, new pavements experience an average percent reduction of approximately 33% in their remaining service life, while older pavements suffer a reduction of about 17%. The statistical analyses indicate that utility cuts caused significant damage, and supported a tiered utility cut fee structure based on functional classification, age of pavement, and size of the cut. The resulting fee schedule is based on 2021 material and construction cost estimates; consequently, implementation including an annual adjustment for inflation is recommended. Example fee calculations are provided.

The effect of some vegetable origin oils used in different clove varieties against Meloidogyne incognita

Alternative control methods are needed against plant parasitic nematodes in Gerbera (Gerbera jamesonii L.) and Carnation (Dianthus caryophyllus L.) plants and one of these methods is the use of plant-based extracts against nematodes. Plant parasitic nematodes cause economic damage in cut flower production areas, so in order to reduce this damage, it is aimed to use different non-synthetic plant-based extracts as an alternative to chemical control methods within the scope of cultural control of nematodes. For this purpose, garlic, thyme, and terminator (70% thyme + 30% different plant mixture formation) were used to determine the resistance against M. incognita in two different clove cultivars, Turbo with standard flower type and Harnet with spray flower type. While the egg pack index was 1.40 ± 0.70 in the Harnet cultivar with garlic application, this rate was 16.00 ± 9.66 in the positive control. While the egg pack index was 1.20 ± 0.42 in the Turbo variety, in which garlic was applied, this value was 3.70 ± 0.48 in the control. When evaluated based on varieties, the egg package index was lower in the Turbo variety with garlic application compared to the Harnet variety.

Risk factors and skin colonization/recolonization – a matter in the development of sternal wound infection after cardiac surgery

Abstract Cardiac surgeries are classified as “clean procedures” as they do not involve access to any space populated by the patient’s microbiota. Nevertheless, the development of sternal wound infection (SWI) can sometimes occur. The aim of the study was to analyze risk factors of SWI, efficacy of antiseptics procedures, skin microbiota colonization/recolonization, and their impact on infection development in patients undergoing cardiac surgery. Of 500 patients who had undergone cardiac surgery through a median sternotomy, perioperative swabs of standardized surgical cut area were taken at three-time points: ‘1’-after admission to treatment rooms, ‘2’-before incision; ‘3’-before chest reconstruction. Material was cultured and grown bacterial colonies were counted. Out of the total population, 23 patients developed SWI and 11 had suspicion of SWI while 466 were without SWI. Risk factors which had statistically significant impact of infection development were high body mass index (BMI) and use of cardiopulmonary bypass (CPB) during operation. The most common SWI-pathogens were coagulase-negative staphylococci (CoNS) and Gram-negative bacilli. From the perioperative period, CoNS and Staphylococcus aureus were isolated. When simultaneous positive cultures in ‘swab-1 and -3’ were observed (respectively, ≥87 and ≥17 bacterial colonies), the risk of complications was higher (patients with SWI – 69.57%; without SWI – 6.71%). Regarding point ‘3’, significant differences were noted in the general level of grown colonies. About 3 times more bacterial colonies were grown in the group with healing problems and SWI. SWI development is multifactorial. The rate of skin microbiota recolonization during surgery may suggests that being more colonized in the surgical incision area was more susceptible to local complications.

Evaluation of Procalcitonin and Presepsin in prediction for early onset neonatal sepsis.

Objective: To determine the presepsin and procalcitonin significance in cord blood and compare with lactate and C-Reactive protein for early prediction of neonatal sepsis. Study Design: Case Control Study. Setting: Military Hospital Rawalpindi. Period: Sep 2018 to July 2019. Methods: Mothers, having deliveries with early or prolonged rupture of membrane, preterm, dai handled, meconium and failure of induction have been included. Out of 60 neonates, nineteen were cases with a clearly documented suspicion of sepsis and confirmed by neonatologists, remaining were control. Mean and Standard Deviation were calculated. The difference in all biochemical markers levels among case and control groups were assessed by independent t-test. Sensitivity, specificity, accuracy, and predictive value of both markers were calculated by medcalc diagnostic calculator. Regression analysis to access the strength. Receiver Operating Characteristics curve for most accurate cut off values and Area Under the Curve was calculated. Results: Independent sample t test revealed the strong association of procalcitonin and presepsin with neonatal sepsis. Presepsin has higher positive predictive value 83.33% and negative predictive value 90.48% with 88.33% accuracy while procalcitonin has positive predictive value 62.50%, negative predictive value 88.89% and accuracy 78.33%. Stepwise regression analysis showed better in combination than single in predication of neonatal sepsis. The cutoff value for procalcitonin was 0.4ng/ml (AUC of 84.5%.) and for presepsin was 305pg/ml (AUC of 86.5%). Conclusion: In comparison to lactate and CRP, a prediction model that incorporates two biochemical indicators, procalcitonin and presepsin, can reduce infant mortality and morbidity by spotting neonatal sepsis early.

Damage prediction and improvement method based on cutting mode of circular empty hole

Based on the theory of empty hole effect of cutting blasting, the Hopkinson effect and Saint–Venant principle are integrated to establish a two-dimensional calculation model of dynamic stress evolution of the holes wall, and then the dynamic fracture mechanism and damage distribution mode of the rock mass in the cutting area under the action of longitudinal waves are predicted. The results of the calculation and numerical simulation are verified by experiments, and the results show that: The time-varying stress function of the circular cavity wall conforms to the periodic dynamic evolution of the trigonometric function, and the theoretical calculation is consistent with the simulation results. Through the calculation of the round holes cut model and the square empty hole cut model, the change of the shape of the holes in the cut area changes the failure form of the surrounding rock mass. The circular empty hole wall is affected by the stress wave to produce "interval ring" destruction, and the effect of the reflected stretch wave is inhibited. The large range of rock mass in the square empty hole wall produces tensile and shear failure, and the rock mass collapses inward under the influence of the second stage stress. Among them, the empty space utilization rate of the square empty hole model is about 8.5 times that of the circular holes model. Vibration monitoring in the center of the cutting area shows that the vibration effect of the circular empty hole is larger than that of the square empty hole, and the proportion of rock breaking energy is lower.

A conceptual cost estimation model for the pre-design stage of road projects using multiple regression analysis

PurposeThe current estimation practice in construction projects greatly needs upgrading, as there has been no improvement in the cost overrun issue over the past 70 years. The purpose of this research was to develop a new multiple regression analysis (MRA)-based model to forecast the final cost of road projects at the pre-design stage using data from 43 projects in New Zealand (NZ).Design/methodology/approachThe research used the case study of 43 completed road projects in NZ. Document analysis was conducted to collect data, and statistical tests were used for model development and analysis.FindingsEight models were developed, and all models achieved the required F statistics and met the regression assumptions. The models’ mean absolute percentage error (MAPE) was between 21.25% and 22.77%. The model with the lowest MAPE comprised the road length and width, number of bridges, pavement area, cut and fill area, preliminary cost and cost indices change.Research limitations/implicationsThe model is based on road projects in NZ. However, it was designed to be able to adapt to other contexts. The findings suggest that the model can be used to improve traditional conceptual estimating methods. Past project data is often stored by the project team but rarely used for analysing and forecasting purposes. This research emphasises that past data can be effectively used to predict the project cost at the pre-design stage with limited information.Originality/valueNo research was conducted to adopt cost modelling techniques into the conceptual estimation practice in the NZ construction industry.

Hydrothermal performance analyses of an isothermal tube with punched twisted tape turbulator (PTT)

This study represents a pioneering investigation into the impact of a punched twisted tape turbulator on the hydrothermal parameters of a pipe operating under constant surface temperature conditions. The punched turbulator was specifically designed by incorporating cuts with diverse geometries, including semicircular, square, and triangular shapes, into the basic twisted tape turbulator. To evaluate the performance of the punched twisted tape, a comparative analysis was conducted with both a smooth tube and a tube equipped with a basic turbulator. The criterion for selecting the optimal cut geometry was the thermal enhancement factor. Subsequently, the influence of the cut area on the hydrothermal parameters was thoroughly elucidated. The enhancement factor was again utilized to identify the most optimal area. Based on the comprehensive evaluations, it was observed that the turbulator with a semicircular cut geometry and a diameter of 5 mm exhibited superior thermal performance compared to all other geometries. By employing this specific turbulator design, a remarkable enhancement in heat transfer and pressure drop within the heat exchanger was achieved, offering improvements of up to 1.63 and 3.65 times, respectively, when contrasted with the plain tube. The maximum enhancement factor value recorded during the investigation reached 1.09.

Morphological reconstruction during cell regeneration in the ciliate Spirostomum ambiguum

When the ciliate Spirostomum ambiguum is transected into two pieces, both fragments regenerate and proliferate. In the anterior fragments, which have lost their contractile vacuoles due to transection, new contractile vacuoles were formed at their posterior ends in a few minutes. When the cells were cut into three pieces, new contractile vacuoles were formed in the anterior and middle fragments, both at their posterior ends. Thus, the anterior-posterior axis of S. ambiguum was maintained after transection. Morphological repair, including the formation of the contractile vacuole, was also observed when only the anteriormost portion was transected to cut out a small fragment that did not contain part of the macronucleus. Scanning electron microscopy was performed to observe changes in the shape of the cleavage surface of S. ambiguum during the wound healing process. Within minutes after cutting, the cut surface was covered with a cilia-free membrane, preventing leakage of cytoplasmic contents. The surface of the cut area then rounded with time and was covered with cilia, completing the repair of the cut area in about one day.

Сравнительный анализ механического и фемтолазер-ассистированного методов выкраивания лимбальных мини-трансплантатов в эксперименте

Original article Experimental study of manual and femtosecond laser-assisted methods for cutting limbal mini-transplants B.E. Malyugin, S.A. Borzenok, O.N. Nefedova, D.S. Ostrovskii, M.Yu. Gerasymov, A.V. Shatskikh S. Fyodorov Eye Microsurger y Federal State Institution, Moscow, Russian Federation A. Yevdokimov Moscow State University of Medicine and Dentistr y, Moscow, Russian Federation Purpose. To define optimal parameters of femtosecond laser (FSL) (Femto LDV Z8, Ziemer, Switzerland) for cutting limbal mini-transplants to be further used for limbal stem cells (LSC) transplantation and compare the results with manual cutting technique using microsurgical blade. Material and methods. At first step, performed on 3 porcine and 3 cadaveric eyes, the optimal energy parameters of FSL were selected, which ensured the excision of limbal mini-transplants. At the second step, 8 eyes from 4 postmortem donors were used. In the lower and upper parts of the limbus, limbal fragments were cut out into 8 mini-transplants with a FSL (experimental group). Mini-grafts were also formed manually in symmetrical areas of each eye using dosed diamond blade (control group). The structure of the limbal bed after removing mini-transplants was studied by light and scanning electron microscopy. The effect of FSL energy on the viability of LSC was determined by intravital staining using Live & Dead dye. Finally, on the third step, the assessment of reversible and irreversible apoptosis was performed by culturing corneoscleral discs containing mini-transplants not separated from the limbal bed. The obtained samples were cultivated in a medium DMEM/F12 for 7 days followed by immunohistochemical examination. Results. The optimal parameters of FSL operation are determined by energy levels- 100, 110 and 120%. Histological analysis of the limbal residual bed zone showed that the smoothest surface was obtained at energies 110 and 120%. This fact was also confirmed by scanning electron microscopy. When stained with the Live & Dead dye, damage on the lateral and inner sides of limbal mini-transplants was revealed, mainly in the experimental group. After 7 days of cultivation in the cut area in both groups, no expression of apoptosis markers was observed. Conclusion. Cutting out the limbal zone containing LSCs using FSL is safe and allows obtaining limbal mini-grafts. The most optimal parameters of laser operation in the limbal zone were selected – a planar cut at depth of 250 µm using 110% laser energy. Key words: femtosecond laser, limbal stem cells, apoptosis, limbal stem cell deficiency syndrome, scanning electron microscopy, light microscopy, cultivation, histology

Solid-liquid mixing characteristics in a fractal cut impeller stirred reactor with dense solid loading

The fractal cut impeller (FC impeller) based on fractal iteration of “H” pattern cuts on the impeller blades was introduced in the solid-liquid system with dense solid loading. The solid-liquid mixing characteristics in a stirred tank with pitched blade impeller (PB impeller) and FC impeller were comparatively investigated with experiment and numerical simulation. Results showed that FC impeller exhibited lower power consumption (P) and power number (Np) compared to PB impeller at the same impeller speed. It could be also observed that increasing the fractal iteration number of FC impeller led to a further decrease in P and Np. Meanwhile, FC impeller could reduce the size of impeller tailing vortex, enhance turbulent intensity and turbulent kinetic energy dissipation rate, and improve solid particle suspension quality compared to PB impeller under the constant power consumption, and an increase in fractal iteration number of FC impeller resulted in higher solid particle suspension efficiency. In addition, it was also found that the fractal arrangement of cuts on the impeller blades could increase turbulent intensity, enhance turbulent kinetic energy dissipation rate and facilitate an improvement in solid particle suspension quality as compared to a whole cut on the impeller blades with equal cut area.

Features of using the over-skiving method for multi-pass cutting of external gears

Problem. There is a problem of determining the working parameters, including axial feed and cutting speed, as well as the helix angle of the teeth of the disc cutter and the tool spindle, the geometry of the cutting part, and the cutting depth per pass in Power skiving technology.Objective. It is necessary to investigate the cutting process using the Power Skiving method for generating external gears over multiple passes and develop recommendations for selecting its optimal parameters.Implementation methodology. The cutting force and its tangential component acting on the cutter are presented based on the fundamental principles of cutting theory, using the function of the cross-sectional area of the cut, the material strength limits of the workpiece for shear, and the intensity of plastic deformation of the chip. Calculations of the cut area are based on a graphoanalytical 3D model of the undeformed chip. The coefficient of shear intensity is determined depending on the thickness of the cut layers using the Deform 2D system. The study of the force factors is conducted in the initial stage for single-tooth cutting, considering the operation of a single tooth of the tool, and for multi-tooth cutting conditions, corresponding to real cutting and forming conditions in this method.Results. Analysis of harmonic vibrations with different frequencies of the investigated forces indicates that, under average loading, the maximum principal component of the cutting force occurs on the third pass, and the tangential force on the tool axis occurs on the first pass. The variation in the frequency of these signals is explained by changes in the contact angle between the tool and the gear wheel in the machine engagement and the different number of teeth involved in cutting.Conclusions. The obtained data allowed the development of a methodology for selecting rational parameters - axial feed values, the number of passes with different cutting depths to minimize time consumption, and achieve the desired accuracy of gears. It has been demonstrated that to reduce processing errors, it is most rational to decrease cutting force by increasing the number of passes, rather than reducing the axial feed.

Metallurgical Analysis in the Outer Tube Fault Area

In the automotive manufacturing industry, product failures are still found. In this study, one of the automotive components, namely the outer tube of the motorcycle front fork, was cracked. The outer tube is part of the shock absorber component which is also connected to the motorcycle steering system. Failure analysis aims to obtain some data or facts that can indicate the root cause of the failure or failure. Sample preparation which includes the process of selecting the cut area, cleaning and cutting for the fractography process. As for metallography, sample preparation is continued with the process of mounting, sanding, polishing and etching. Fractographic test showed that the fracture occurred in a brittle fracture mode, with no traces of plastic deformation. The morphology of the fracture surface also shows the presence of gas trapped in large quantities. In the metallographic test, the overall microstructure shows an eutectic phase with a uniform dendrite structure pattern, this indicates that metal solidification occurs quite quickly and can cause a lot of gas to be trapped in the metal characterized by the presence of multiple porosities. This can provide an indication of the relationship between the microstructure and the fracture surface morphology. Cracking and brittle fracture can be caused by the stress that occurs in the metal that exceeds the yield and plastic limits due to the large pressure of gas trapped in the metal.

Carbon mapping in pine-oak stands under timber management in southern Mexico.

The destructive and empirical methods commonly used to estimate carbon pools in forests managed timber are time-consuming, expensive and unfeasible at a large scale; satellite images allow evaluations at different scales, reducing time and costs. The objective of this study was to evaluate the tree biomass (TB) and carbon content (CC) through satellite images derived from Sentinel 2 in underutilized stands in southern Mexico. In 2022, 12 circular sites of 400 m2 with four silvicultural treatments (STs) were established in a targeted manner: 1st thinning (T1), free thinning (FT), regeneration cut (RC) and unmanaged area (UA). A tree inventory was carried out, and samples were obtained to determine their TB based on specific gravity and CC through the Walkey and Black method. The satellite image of the study area was downloaded from Sentinel 2 to fit a simple linear model as a function of the Normalized Difference Vegetation Index (10 m pixel-1) showing significance (p≤0.01) and a adjusted R2 = 0.92. Subsequently, the TB and CC (t ha-1) were estimated for each ST and managed area. The total managed area (3,201 ha-1) had 126 t TB ha-1 and 57 t C ha-1. Of the areas with STs, the area with FT showed the highest accumulation of TB (140 t ha-1) and C (63 t ha-1) without showing differences (p>0.05) with respect to those of the UA, which presented 129 t TB ha-1 and 58 t C ha-1. The satellite images from Sentinel 2 provide reliable estimates of the amounts of TB and CC in the managed stands. Therefore, it can be concluded that an adequate application of STs maintains a balance in the accumulation of tree C.

Restorative dynamics of pine phytocenoses in clearcut areas in the floodplain terraces of the Moscow River

Initial stages of restoration dynamics of phytocoenoses are of a special interest. Ecological conditions change crucially after timber harvesting. The exploration of two clearcut areas in the Moscow River valley in 3-5 years after felling allowed us to detect the direction of phytocoenosis dynamics. Scotch pine ( Pinus sylvestris L.) losses the competition with deciduous species in both sites constituting less than 50 % of regeneration. The largest number of individuals of Pinus sylvestris L. at the research sites, they have a three-year age: clear cut area No. 1 - 55 % and clear cut area No. 2 - 47 %. An intensive height increment of prevailing tree species was registered. In the site No. 1, an annual increase in height increment was registered indicating favourable growth conditions, while in the site No. 2, the 4-centimeter reduction of height increment was observed in the last year. The soil vegetation cover is an important ecological factor regulating the restoration dynamics of phytocoenoses on clearcut areas. To estimate the restoration dynamics of soil cover vegetation, 45 geobotanical descriptions were made. Totally 102 species of vascular plants referred to 72 genera were found on clearcut areas. The families with the highest frequency were Asteraceae - 12,7 %, Apiaceae - 10,8 %, and Poaceae - 8,8 %. A noticeable presence of Poaceae in the vegetation cover limits successful reforestation. The percentage of the most widespread ecologo-coenotic groups is 45% of the total number of registered species for meadow herbs, 16 % for tall herbs, 11 % for nemoral species, and 9% for forbs. Summary average projective coverage of herbage is 65-75 %. Under the conditions of reed-grass - herbal type of clearcut areas, Scotch pine is suppressed by both deciduous species and herbal vegetation, which makes the perspectives of its predomination in the future stand doubtful.

Auxetic Photonic Patterns with Ultrasensitive Mechanochromism.

Photonic crystals with mechanochromic properties are currently under intensive study to provide intuitive colorimetric detection of strains for various applications. However, the sensitivity of color change to strain is intrinsically limited, as the degree of deformation determines the wavelength shift. To overcome this limitation, auxetic photonic patterns that exhibit ultra-sensitive mechanochromism are designed. These patterns have a regular arrangement of cuts that expand to accommodate the strain, while the skeletal framework undergoes torsional deformation. Elastic photonic crystals composed of a non-close-packed array of colloidal particles are embedded in the cut area of the auxetic patterns. As the cut area amplifies the strains, the elastic photonic crystals show significant color change even for small total strains. The degree of local-strain amplification, or sensitivity of color change, is controllable by adjusting the width of cuts in the auxetic framework. In this work, a maximum sensitivity of up to 60nm/% is achieved, which is 20 times higher than bulk films. It is believed that the auxetic photonic patterns with ultra-sensitive mechanochromism will provide new opportunities for the pragmatic use of mechanochromic materials in various fields, including structural health monitoring.

Self‐healing thermoplastic elastomeric blends of zinc‐ionomer and styrene–butadiene–styrene block copolymer and their characterization

AbstractWe report the development of novel self‐healing binary thermoplastic elastomeric blends of Zn2+‐neutralized poly[ethylene‐co‐(methacrylic acid)] (Zn‐ionomer) and styrene–butadiene–styrene block copolymer (SBS). Zn‐ionomer/SBS blends were prepared by the melt‐blending technique using a twin‐screw extruder with three mass ratios of 75/25, 50/50 and 25/75. Structure, phase morphology and thermal as well as tensile properties of the samples were characterized. Fourier transform infrared spectroscopy results indicated the presence of two types of polymeric materials and their interactions. Scanning electron microscopy images confirmed the miscibility of blend components which remarkably influenced the properties of the blends. The optimum peak degradation temperature of Zn‐ionomer/SBS (75/25 wt%) blend was observed to be 484 °C. The ratio of the tensile strength of the healed specimens to that of the original specimens was implemented to quantitatively evaluate the self‐healing efficiency of the materials. The self‐healing efficiencies were calculated to be 55.42%, 58.36% and 60.75% for Zn‐ionomer samples healed for 4, 8 and 16 h, respectively. All of the blend samples exhibited self‐healing behavior and the self‐healing efficiency was more than that of virgin Zn‐ionomer which may be credited to the high mobility of SBS segments in the blends. The healing efficiency was increased with an increase of SBS content in the blends and also heat energy facilitated the healing process. The self‐healing efficiencies of Zn‐ionomer/SBS (25/75 wt%) blend sample were calculated to be 75.09%, 80.27% and 80.87%, respectively, for 4, 8 and 16 h of healing time at 100 °C. A comparison of optical micrographs of the cut area of samples (before healing and after the healing process) was also made and self‐healing of the blend materials was observed. © 2023 Society of Industrial Chemistry.

Bioindication of the Dark Gray Soil State in the Pine Forests of the Krasnoyarsk Forest-Steppe under Anthropogenic Influence

The biological activity of dark gray soil was studied in a 100-year-old pine forb-green-moss forest of the Pogorelsky pine forest of the Krasnoyarsk forest-steppe. In 2017, selective cuttings were carried out in the pine forest, and in May 2022 there was a strong fire. To improve reforestation and increase the biological productivity of the soil, bio-fertilizer based on sawdust-soil substrate with the addition of urea and mycoproduct (SSSU + M) was applied to cut and burned areas. On the experimental plots (Paseka, Volok, Fon), an annual count of self-seeding of pine was carried out. Bioindication of the soil condition was assessed based on the total number and ratio of ecological-trophic groups of microorganisms, enzyme activity, microbial biomass content, intensity of basal respiration and specific respiration of microbial biomass. The application of biofertilizer to the cut areas alkalized the soil by 0.2–0.4 units, retained moisture, increased the content of nitrogen (by 5–14%) and microbial biomass (by 1.2–1.6 times), compared with the control options. The impact of biofertilizers on the germination and growth of self-seeding of pine was noted in the second year after application – in the experimental plots of self-seeding it was 4–6 times greater than in the control ones. The entry of burnt plant residues, coals and ash into the soil in the first week after the fire led to an increase in some microbiological indicators, the activity of urease and invertase, and the activation of carbotrophic microorganisms. However, by the end of the growing season, a decrease in microbiological activity was noted, which indicated a post-pyrogenic depression of microbocenoses. The introduction of biofertilizer on the burnt surface of the plots leveled the effect of pyrogenic effects and stimulated the formation of shoots of scots pine, the number of which was significantly higher than in the control plots. It was found that the universal bioindicators that adequately reflect the state of the soil after all anthropogenic impacts were microbial biomass, specific microbial respiration, enzymatic activity and the total number of microorganisms. A specific bioindication of the soil condition after the fire was an increase in the proportion of bacteria Serratia plymuthica, Bacillus mycoides and fungi of the genera Trichoderma, Penicillium and Mortierela.

Design of a Mini Rice Harvester for Rural and Small Scale Rice Farmers in Tropical and Developing Countries

Food insecurity, price volatility and under-employment of rice farmers in Liberia are key drivers for the development of rice farming machines locally. This project work aims to design and fabricate a simple, low-cost, efficient mini rice harvester powered by a solar panel by translating learnt concepts and principles of engineering into a physical and workable rice harvester. A circular blade cutter, DC motor, DC battery and solar cells are the main components deployed on a rod-plate setup. The solar cell taps solar irradiance from the sun and, with the help of a charge controller, recharges a 12V, 35Amp.hour battery. The battery supplies DC current to a DC motor that drives a circular blade cutter during harvesting. The fabricated harvester fulfilled all design objectives and was justifiable on overall financial cost (USD 194.00), ease of use, and ease of reproduction. The performance of the harvester, in terms of smoothness of cut and completion of cut area, was found to be near 100%. However, the harvester field efficiency performance was found to be 30.75% with an aggregated efficiency of % and a payback period of only 71 hours of operation, equivalent to 60,696 sq.m of harvested rice farm. Incessant clogged cutter's surface and harvested stem removal delays, slowdowns as the operator makes turns, switch failures and re-fix delays during field tests are the primary causes of the low field efficiency. With an improved spacing between the blade cutter and the secondary guard, the performance of the harvester is expected to improve significantly. An average noise level of 88.8 decibels was detected during the harvester's operation; advisably, hearing protection earmuffs may be necessary to safely operate the mini harvester on the dailies for 6 hours. Notwithstanding that the effect of moisture content of the rice stalks, as an input parameter, was not considered in the development of the power requirement for the rice cutter, the harvester can be optimized with minimal effort for commercialization and adopted as a Made-In-Liberia invention.

Evaluating cone cut in rectangular collimation in intraoral radiography: application of ALADA and radiation stewardship

ObjectiveRectangular collimation is a popular method used in intraoral radiography to reduce patient exposure to ionizing radiation. One of the perceived drawbacks of rectangular collimation is the possibility of an increase in cone cut errors ultimately impacting the diagnostic value of the radiographs. Thus, the aim of this study was to explore the frequency of cone cut errors in radiographs taken using a rectangular collimator.Materials and methodsRadiographs taken using PSP plates at Academic Center for Dentistry Amsterdam in the Netherlands by staff and students from January to December 2015 were assessed for cone cut errors. The radiographs were grouped as bitewings, front teeth, inferior premolars and molars, and superior premolars and molars and categorized as no cone cut, cone cut but diagnostically usable, and cone cut but diagnostically not usable. The results were entered into Microsoft Excel and analyzed thereafter.ResultsA total of 53,684 radiographs were assessed, 79% had no cone cut errors and consequently 21% had some degree of cone cut. However, the diagnostic value was unaffected in 18% of the radiographs with cone cut. Only 3% of the radiographs were deemed diagnostically unusable due to cone cut. The most common area of cone cut was in the premolar and molar areas while cone cut in the front teeth was least likely to be diagnostically unusable.ConclusionCone cut from the use of a rectangular collimator does not seem to result in an increase of diagnostically unusable radiographs. Thus, rectangular collimation should be preferred as it decreases the amount of radiation exposure to the patient while producing diagnostically usable radiographs and thus allowing the dental professional to adhere to the ALADA principle and practice radiation stewardship.Clinical relevanceScientific rationale for the study: rectangular collimation is a method used to reduce patient exposure to ionizing radiation; however, this benefit is negligible if radiographs must be retaken due to cone cut errors that make the radiograph diagnostically unusable. Therefore, the aim of this study was to explore the frequency of cone cut in radiographs taken using a rectangular collimator. Principal findings: cone cut was observed in 21% of the radiographs; however, only 3% of the radiographs were considered diagnostically unusable. Practical implications: rectangular collimation does not result in a high number of diagnostically unusable radiographs and should be used to reduce patient exposure to ionizing radiation.

Analysis of Lead (Pb) and Cadmium (Cd) in Oyster Crassostrea gigas and Saccostrea cucullata using Atomic Absorption and Ultraviolet-Visible Spectrophotometer Methods

Lead (Pb) and Cadmium (Cd) metals are highly toxic when accumulated in the body and cause serious diseases and even death. This study aimed to determine the metal content of Pb and Cd in the oyster species Crassostrea gigas and Saccostrea cucullate in the Lampulo and Krueng Cut areas at three different places. Analysis of the metals was carried out using AAS and UV-Visible spectrophotometers. Samples were prepared using concentrated HNO3 wet destruction and the addition of dithizone. The results showed Pb measured by AAS in Saccostrea cucullata 2.33-8.00 ppb, and by UV-Vis 2.77-8.66 ppb. Pb within Crassostrea gigas by AAS method 1.77-10.30 ppb, and by UV-Vis method 2.11-10.66 ppb. The Cd metal measured by AAS in Saccostrea cucullate is 3.80-10.50 ppb, and by UV-Vis method is 4.29-10.77 ppb, whereas Cd in Crassostrea gigas measured by AAS is 12.11-13.22 ppb and by UV-Vis method is 12.77-13.66 ppb. Linearity of Pb measurements with AAS and UV-Vis was obtained R2 =0.9979 and R2 =0.9938 and for Cd were R2 =0.9986 and R2 =0.9810. Accuracy (%recorvery) of Pb measurements by AAS and UV-Vis are 80-110% and 98-113% whereas Cd showed 100-106% and 91-107% respectively. The relative value of the standard deviation (%RSD ± SD) is 0.001 indicating excellent measurement results. Based on t-test calculations, measurements of Pb and Cd levels showed no difference between the AAS method and the UV-Vis method