Kinetics Of Production Research Articles

Characterization of β-Hydroxybutyrate as a Cell Autonomous Fuel for Active Excitatory and Inhibitory Neurons: β-Hydroxybutyrate as a Fuel for Active Neurons.

The ketogenic diet is an effective treatment for drug-resistant epilepsy, but the therapeutic mechanisms are poorly understood. Although ketones are able to fuel the brain, it is not known whether ketones are directly metabolized by neurons on a time scale sufficiently rapid to fuel the bioenergetic demands of sustained synaptic transmission. Here, we show that nerve terminals can use the ketone β-hydroxybutyrate in a cell- autonomous fashion to support neurotransmission in both excitatory and inhibitory nerve terminals and that this flexibility relies on Ca2+ dependent upregulation of mitochondrial metabolism. Using a genetically encoded ATP sensor, we show that inhibitory axons fueled by ketones sustain much higher ATP levels under steady state conditions than excitatory axons, but that the kinetics of ATP production following activity are slower when using ketones as fuel compared to lactate/pyruvate for both excitatory and inhibitory neurons.

Efficacy of Salvia officinalis Shrub as a Sustainable Feed Additive for Reducing Ruminal Methane Production and Enhancing Fermentation in Ruminants.

The objective of this study was to evaluate the effects of the inclusion of dried Salvia officinalis (SO) shrub leaves on nutrient degradability, ruminal in vitro fermentation, gas production (GP), methane (CH4), and carbon dioxide (CO2) productions. Dried and ground SO shrub leaves were included at 0% (control), 0.5%, 1%, 1.5%, and 2% DM of a diet consisting of (per kg DM) 500 g concentrate feed mixture, 400 g berseem hay, and 100 g rice straw. The diet was incubated for 48 h. The asymptotic GP and the rate of GP changed linearly and quadratically (p < 0.01), with the highest GP observed at 1% inclusion of SO and then decreasing thereafter with greater inclusion (i.e., 1.5% and 2%), while CH4 production and its rate decreased linearly (p < 0.01) with all levels of SO inclusion. A linear increase in CO2 production and its rate was also found with an increasing level of SO inclusion in the diet (p < 0.05). Furthermore, the degradability of DM, NDF, and the concentration of total short-chain fatty acids and acetate changed linearly and quadratically, with the greatest being found at 1% SO inclusion and then steadily declining after (p < 0.01) with the 1.5% and 2% inclusion levels. Meanwhile, the propionate, NH3-N, and microbial crude protein levels showed similar trends, with the plateau found at 1% inclusion of SO, where there was no change in butyrate concentration. Moreover, the pH, metabolizable energy, and partitioning factor (PF24) also changed linearly and quadratically (p < 0.05), where the pH and PF24 were considerably reduced and ME increased with a 1% inclusion of SO (p < 0.05). In summary, SO at 1% inclusion in the diet showed the potential to improve gas production kinetics, nutrient degradability, and the ruminal fermentation profile, with a more significant reduction in ruminal CH4 production suggesting that SO at 1% could be included in the ruminant diet to reduce their carbon footprint and increase the production performance.

Assessing nutritional quality and gas production kinetics: incorporating Tithonia diversifolia into sugarcane silage

Assessing nutritional quality and gas production kinetics: incorporating Tithonia diversifolia into sugarcane silage

Feasibility of a Tungsten-181 HDR brachytherapy source: Analysis of isotope production and source dosimetry

BackgroundInterest in Intensity Modulated Brachytherapy (IMBT) for High Dose Rate Brachytherapy (HDR) treatments has steadily increased in recent years. However, intensity modulation is not best optimized for currently used HDR sources since they emit high energy photons. To that end, the focus on IMBT has moved to middle energy sources, such as Ytterbium-169; yet even Yb-169 emits some high energy photons at a low yield. We present an alternative isotope, Tungsten-181 (T1/2 = 121 days) that is interesting due to its complete lack of high energy photon emissions. (Eavg = 58.9 keV, Emed = 57.5 keV) making it potentially favorable as high dose rate brachytherapy source from both a medical physics and health physics perspective. PurposeThe purpose of this study was to determine the feasibility of using W-181 as an HDR brachytherapy source; in this study we focused on W-181's production, dosimetric properties, and intensity modulation capabilities. MethodsWe determined the isotope production kinetics, its Dose Rate Constant, Radial Dose Function, photon self-absorption, and the shielding intensity modulation capabilities for a W-181 pellet source geometry using the MCNP6.2 Computer Simulations Code. All simulations were performed using a personal computer running an AMD Ryzen 5 3600 6-Core Processor 3.59 GHz. The number of histories run for each study were selected to produce relative simulation convergence errors in the MCNP tally output of less than 2%.Dosimetric calculations were made using the MCNP6.2 computer simulations code and activation analyses were determined mathematically using a Catenary kinetics analysis (also known as a Bateman Analysis) of W-181 and Tantlum-182 production from the neutron activation of a pure Tungsten-180 stable target. Since W-181 emits middle energy photons and has a high density, we also assessed the effects of photon self-absorption within a tungsten pellet. ResultsFrom our analysis, we determined that a 3.5 mm long and 0.6 mm in diameter is feasible for clinical applications. Our activation analyses found that these pellets can achieve W-181 activities up to 7.9Ci and 13Ci using neutron fluence rates of 4E14 cm−2 s−1 and 1E15 cm−2 s−1 respectively, which then would provide a dose rate of 1.84 ± 0.01 cG y/Ci/min at a depth of 1 cm from the source. Using our resulting Monte Carlo simulated Dose Rate Constant of 1.24 ± 0.02 cGy h−1∙U−1, a W-181 source in this geometry would require a source activity upwards of 10Ci for use in HDR treatments. In the intensity modulation analysis, only 0.1 mm of gold shielding was found to reduce a pellet's absorbed dose by over 50% while 0.3 mm of gold shielding, which is thin enough to theoretically fit between an HDR pellet and the inner catheter wall, was found to reduce the pellet's absorbed dose by over 85%. ConclusionsWhile W-181 has a lower specific activity than Ir-192 and Yb-169, it shows great promise as an isotope for use in Intensity Modulated Brachytherapy due to its easily shielded photons. We therefore expect that W-181 may lend itself best for use as a multi-pellet configuration in IMBT.

Efeito de um aditivo fúngico multiespécie no perfil de fermentação ruminal, de-gradabilidade e cinética de produção de gases

Two experiments evaluated the effect of a multispecies fungal complex (BP, BIOPREMIX MX®, Ruminal Fermentation Tech, Uruguay). In Experiment 1 (E1), the impact of adding BP to a total mixed ration (TMR) on ruminal fermentation profile and TMR in situ degradation kinetics was assessed. In Experiment 2 (E2), the effect of adding BP to various substrates on in vitro fermentability was examined. In E1, 4 Holstein cows with rumen cannulas were randomly assigned to Control (TMR with forage:concentrate ratio 75:25) or Control + 120 g/cow/d of BP (BP) and received ad libitum TMR for 30 days. Samples of TMR were ruminally incubated to estimate in situ degradation kinetic. Ruminal pH, ammonia, and volatile fatty acids (VFA) concentrations were measured just before feeding, 4 h and 8 h post feeding. In E2, a factorial arrangement included two BP levels (0 -Control or 6.5 g BP per kg dry matter incubated-WBP) and 8 substrates. In vitro gas production kinetics (GPk), dry matter digestibility (IVDMD), methanogenic potential (CH4), partitioning factor (PF), VFA, and microbial crude protein (MCP) were estimated. The BP increased proportion of propionate (P ≤ 0.05) and reduced ketogenic:glucogenic ratio and Lag phase of NDF (P ≤ 0.05). WBP tended to increase IVDMD, and substrate affected GPk, IVDMD, CH4, PF, VFA and MCP (P ≤ 0.01). Overall, BP improved ruminal metabolism favoring a more glucogenic profile, a shortening Lag phase in NDF degradation, and increasing IVDMD.

The Enterococcus secretome inhibits the growth of vancomycin-resistant Enterococcus faecalis V853 with their antiproliferative properties and nanoencapsulation effects.

In our study, the secretome of the clinical isolate Enterococcus faecalis HY7 displayed antibacterial activity against the vancomycin-resistant Enterococcus faecalis V853. These bacteriocin-like substances showed thermal stability at a wide range of temperatures up to 121°C, while proteinase K treatment resulted in a total loss of their activity. PCR-based screening for bacteriocin biosynthetic genes revealed that Enterococcus faecalis HY7 harbored multiple enterocin-producing genes, including ent A, avc A, and as-48. The production kinetics demonstrated the highest levels of bacteriocins production at 16h, whereas the activity was diminished after 32h of microbial growth. Notably, the partially purified bacteriocins exhibited anti-proliferative activity on the colon cancer cells, Caco2, with an IC50 value of 172.8μg/mL. Remarkably, the nanoencapsulation of our bacteriocins in liposome showed a fourfold increase in its anti-vancomycin-resistant Enterococcus activity, which is the first report of liposome encapsulation with anti-vancomycin resistant Enterococcus bacteriocin.

Product regulation and kinetics for fast pyrolysis of corncob over niobium oxide modified zeolite

Catalytic fast pyrolysis is considered as a promising technology for converting biomass into biofuels. In the present research, a series of NbOx modified ZSM-5 catalysts were developed and applied for the selective fast pyrolysis of corncob into aromatics. Depolymerization and hydrodeoxygenation of lignin constituents as well as the aromatization of polysaccharide fractions were the major source of aromatics. The introduction of niobium oxide into ZSM-5 remarkably enriched the Lewis acids and improved the porous structures. The presence of synergistic effect between acid sites and porous structure of NbOx modified ZSM-5 contributed to the aromatics formation in a certain degree. Under the catalysis of 3Nb/ZSM-5, the optimum aromatic content was 86.4 % at 450 °C with a heating rate of 104 °C/s. In the meantime, 3Nb/ZSM-5 presented good stability and recyclability in the fast pyrolysis of corncob, and over 75 % aromatics was achieved even after 3 cycles. Kinetical study revealed that the Ea value for corncob pyrolysis could be lowered to ∼ 250 kJ/mol with conversion rate range of 0.4–0.7.

Rapid Waste Motor Oil Conversion into Diesel-Range Hydrocarbons Using Hydrochar as Catalyst: Kinetic Study and Product Characterization

Herein, raw and alkali-treated hydrochars from biomass waste are prepared as a highly active catalyst for the conversion of waste motor oil into diesel-like fuels. Among all materials, hydrochar obtained at 250 °C and subsequent alkali activation with KOH showed a 600% improvement of the kinetic constant from 0.0088 to 0.0614 m−1. Conversion values at the same conditions were also improved from 66 to 80% regarding thermal and catalytic cracking, respectively. Moreover, the activation energy was also reduced from 293 to 246 kJ mol−1 for thermal and catalytic cracking, respectively. After characterization, the enhanced catalytic activity was correlated to an increased surface area and functionalization due to the alkali activation. Finally, the liquid product characterization demonstrated that catalytic cracking is more effective than thermal cracking for producing hydrocarbons in the diesel range. In particular, hydrochar-based catalysts are suggested to promote the formation of specific hydrocarbons so that the carbon distribution can be tailored by modifying the hydrothermal treatment temperature.

Distinctive effects of graphene oxide and reduced graphene oxide on methane production kinetics and pharmaceuticals removal in anaerobic reactors

Graphene oxide (GO) addition to anaerobic digestion has been suggested to enhance direct electron transfer. The impact of GO (0.075 g GO g−1 VS) and biologically and hydrothermally reduced GO (bio-rGO and h-rGO, respectively) on the methane production kinetics and removal of 12 pharmaceuticals was assessed in Fed-batch reactors. A decrease of 15 % in methane production was observed in the tests with GO addition compared with the control and the h-rGO. However, bio-rGO and h-rGO substantially increased the methane production rate compared to the control tests (+40 %), in the third fed-batch test. Removal of pharmaceuticals was enhanced only during the bio-reduction of GO (1st fed-batch test), whereas once the GO was bio-reduced, it followed a similar trend in the control and h-rGO tests. The addition of GO can enhance the methane production rate and, therefore, reduce the anaerobic treatment time.

Microencapsulation efficiency of fruit peel phytonutrient-based antimicrobial to mitigate rumen emission using in vitro fermentation technique

This research investigated the protecting properties of polyphenols and flavonoids in phytonutrient pellets formulated from lemongrass powder and mangosteen peel (LEMANGOS pellets) through the microencapsulation and named microencapsulated LEMANGOS (mLEMANGOS). For this purpose, the effects of mLEMANGOS supplementation at various R:C ratios of 60:40 and 20:80 were evaluated and compared with monensin (antibiotic) supplementation under an in vitro study technique. Treatments were randomly assigned in a 2 × 4 × 2 factorial arrangement in a completely randomised design consisting of factors A: R:C ratios (60:40 and 80:20), factor B: mLEMANGOS supplementation (0, 2, 4, and 6% DM), and factor C: monensin supplementation (0 and 20% DM). There was an interaction between the R:C ratio and both mLEMANGOS and monensin supplements on the in vitro gas production kinetics, ruminal by-product fermentation, methane production, and rumen microbial population (p < 0.001, 0.01, 0.05). Results indicated that each supplementation influenced the gas production kinetics, while there was decreased cumulative gas production in the mLEMANGOS supplemented. Consequently, the supplemented group buffered ruminal pH and increased the in vitro dry matter degradability (IVDMD) and ammonia nitrogen (NH3-N) concentrations. Moreover, the additional treatment of mLEMANGOS supplementation (6% DM at R:C ratios of 60:40 and 20:80) significantly reduced the number of Methanobacteriales to 53.5% and 50.4% after 24 h, respectively. Results from those supplements can reduce methane production to 99.2% and 97.9% (p < 0.001), respectively. This research suggests that phytonutrient-based antimicrobial in the mLEMANGOS supplement could potentially be used as ruminant feed additives and as antimicrobial substances. HIGHLIGHT Microencapsulated LEMANGOS was formulated by biopolymer using green technique to retain the phytonutrients and their long-term release. The mLEMANGOS supplementation (at 6% of total DM) can be used as a synthetic bio-antibiotic for inhibiting methanogens-archaea population. The mLEMANGOS supplementation (at 6% of total DM) can enhance rumen nutrients degradability, ruminal end-products, and mitigate methane production.

Exploiting the roles of nitrogen sources for HEA increment in Cordyceps cicadae.

Cordyceps cicadae, as a new food ingredient, is a valuable edible and medicinal fungi. However, its resources are severely depleted due to environmental limitations and excessive harvesting practices. N6-(2-hydroxyethyl) adenosine (HEA), as an important product of Cordyceps cicadae, has the potential to be used in medical industry due to its diverse disease curing potential. However, the disclosure of HEA synthesis still severely limited its application until now. In this study, the kinetic curves for adenosine and HEA under shaker fermentation were explored. The kinetics of HEA and adenosine production exhibited a competitive pattern, implicating a possibility of sharing a same step during their synthesis. Due to HEA as a derivative of nitrogen metabolism, the effect of different nitrogen sources (peptone, yeast extract, ammonium sulfate, diammonium oxalate monohydrate, ammonium citrate dibasic, and ammonium citrate tribasic) on HEA production in Cordyceps cicadae strain AH 10-4 had been explored under different incubation conditions (shaker fermentation, stationary fermentation, and submerged fermentation). Our results indicated that the complex organic nitrogen sources were found to improve the accumulation of HEA content under shaker fermentation. In contrast, the optimal nitrogen source for the accumulation of HEA under stationary fermentation and submerged fermentation was ammonium citrate tribasic. But submerged fermentation obviously shortened the incubation time and had a comparable capacity of HEA accumulation by 2.578 mg/g compared with stationary fermentation of 2.535 mg/g, implicating a possibility of scaled-up production of HEA in industry by submerged fermentation. Based on the dramatic HEA production by ammonium sulfate as nitrogen resources between stationary and shaker fermentations, alanine, aspartate and glutamate as well as arginine metabolic pathway were related to the production of HEA by comparative transcriptome. Further investigation indicated that glutamic acid, which is an analog of Asp, showed an optimum production of HEA in comparison with other amino acids.

Effect of long chain fatty acids on biogas production and biochemical kinetics in anaerobic bioreactors: a review

Long Chain Fatty Acids (LCFAs) are the primary intermediate byproduct of the lipid (fats, oils, and greases) degradation process, and if they accumulate in high concentrations, they can cause failure or reduce the performance of anaerobic bioreactors due to sludge flotation issues, biochemical kinetics problems for soluble substrates, inhibition of microbial activity, and inefficient biogas recovery. Understanding the biochemical kinetics of anaerobic bioreactors requires taking into account the entire process, including microbe growth, substrate degradation, and product synthesis. Biochemical kinetics of anaerobic treatment is the study of polymer biodegradation rates of insoluble organic matter in wastewater, which is the mechanism of bond breaking and bond formation in biochemical reactions. As a result, biochemical kinetics allow for the design of both desired and undesirable reaction phases. The kinetic parameters acquired are utilized to design, operate, and optimize anaerobic bioreactors for wastewater treatment on a technical scale.

Production of red beetroot juice by different methods: Kinetics of microbial growth, sugar consumption, and acid production

As a fermentation method, the utilisation of starter culture is a common practice in industrial manufacturing, although spontaneous methods have been employed since ancient times. The objective of this study was to investigate the effect of different production methods on red beetroot juice (RBJ). For this purpose, as a starter culture, the probiotic Lactibasillus paracasei (Lc. paracasei) was inoculated into the RBJ samples after pasteurization. Also, the growth of cells, acid production, and substrate utilisation were monitored throughout the fermentation process of RBJ under two different methods of fermentation.The samples produced by the addition of Lc. paracasei demonstrated a slightly lower decrease in pH values in comparison to the samples obtained by the spontaneous method. The concentration of lactic acid (LA) and acetic acid (AA) at the end of fermentation reveals that Lc. paracasei exhibits a greater capacity for both LA and AA generation compared to the spontaneous method. The ratios of LA and AA molar concentrations of RBJ were determined to be 1.7 and 3.6 for the samples produced by adding Lc. paracasei and the spontaneous method, respectively. The samples produced by adding Lc. paracasei exhibited a greater consumption of sucrose. Both fermentation methods provide LAB counts exceeding 8 log CFU/mL at the end of fermentation.Time demonstrated a significant correlation with LA and AA in the method by adding Lc. paracasei (r = 0.942 and 0.745), respectively (p < 0.01). In both methods, it was demonstrated that while sucrose content decreased during the fermentation period, fructose and glucose content remained constant (p < 0.05).

Divergent Polymer Superstructures from Protonated Poly(adenine) DNA and RNA.

Studies have shown that poly(adenine) DNA and RNA strands protonate at a low pH to form self-associating duplexes; however, the nanoscopic morphology of these structures is unclear. Here, we use Transition Electron Microscopy (TEM), Atomic Force Microscopy (AFM), dynamic light scattering (DLS), and fluorescence spectroscopy to show that both ribose identity (DNA or RNA) and assembly conditions (thermal or room-temperature annealing) dictate unique hierarchical structures for poly(adenine) sequences at a low pH. We show that while the thermodynamic product of protonating poly(adenine) DNA is a discrete dimer of two DNA strands, the kinetic product is a supramolecular polymer that branches and aggregates to form micron-diameter superstructures. In contrast, we find that protonated poly(A) RNA polymerizes into micrometer-length, twisted fibers under the same conditions. These divergent hierarchical morphologies highlight the amplification of subtle chemical differences between RNA and DNA into unique nanoscale behaviors. With the use of poly(adenine) strands spanning vaccine technologies, sensing, and dynamic biotechnology, understanding and controlling the underlying assembly pathways of these structures are critical to developing robust, programmable nanotechnologies.

Numerical study on kinetics of tar production and mechanism of benzene formation during corn straw gasification

Tar production is a key factor hindering the industrialization of biomass gasification technology. Understanding the mechanisms of tar formation can help predict and reduce tar yield. A gasification model was proposed to investigate the effects of oxygen ratio (OR) and temperature on products formation. Its accuracy was validated using experimental data. The relative content of PAHs from corn straw gasification decreased from 95 % to 53 % with OR and temperature increasing, indicating PAHs relative content could be decreased by increasing OR and temperature. The concentrations of phenanthrene from cellulose and corn straw gasification at 900 °C were 0.85 and 378 ppm, separately. The concentrations of pyrene were 52 and 558 ppm, respectively. The content of PAHs from cellulose gasification was much less than that from corn straw gasification. However, the contribution of cellulose to PAHs formation increased with temperature increasing. Furthermore, the mechanism of benzene formation was analyzed qualitatively and quantitatively. C2H2, C3H3, and C4H6 were main precursors and exhibited a considerable role in benzene formation. H, OH, CH3, and C6H5 were the key radicals. The analysis results indicated that CH3→C2H2→C3H3→benzene and C2H3/C2H4→C4H6→n-C4H5→benzene were two main paths for benzene formation during corn straw gasification.

Impact of using glucose as a sole carbon source to analyze the effect of biochar on the kinetics of biomethane production

The adaptation of biochar in anaerobic digestion (AD) positively influences the conversion of substrate to biomethane and promotes system stability. This study investigated the influence of biochar (BC) doses (0 to 8 g/L) on the Biochemical Methane Potential (BMP) of glucose during a 60-day AD in a mesophilic batch-type reactor. The first 6.5 weeks of the experimentation were dedicated to the microorganism’s adaptation to the biochar and degradation of organics from the used inoculum (3 phases of the glucose feeding). The last 2 weeks (4th phase of glucose feeding) represented the assumption, that glucose is the sole carbon source in the system. A machine learning model based on the autoregressive integrated moving average (ARIMA) method was used to model the cumulative BMP. The results showed that the BMP increased with the amount of BC added. The highest BMP was obtained at a dose of 8 g/L, with a maximum cumulative BMP of 390.33 mL CH4/g-VS added. Likewise, the system showed stability in the pH (7.17 to 8.17). In contrast, non-amended reactors produced only 135.06 mL CH4/g-VS and became acidic at the end of the operation. Reducing the influence of carbon from inoculum, sharpened the positive effect of BC on the kinetics of biomethane production from glucose.

Synthesis of Ferrocenyl Boranes and their Application as Lewis Acids in Epoxide Rearrangements

AbstractA series of substituted ferrocenyl boron derivatives was synthesized. The oxidation of the ferrocenyl unit resulted in a significant increase of the boron‐centered Lewis acidity. The neutral and cationic Lewis acids were characterized by NMR spectroscopy, crystal structure analysis and by computational methods. The new Lewis acids were then applied in the Meinwald rearrangement of epoxides, predominantly furnishing aldehydes as the kinetic products.

CO2 capture and methanation using Ru/Na2O/Al2O3 dual-function materials: Effect of support synthesis method and Ru load

Ru/Na2O/Al2O3 dual-function materials were prepared by varying the support synthesis method and Ru load. Different sol-gel-type and precipitation/ hydrothermal preparation methods were employed in order to synthesize materials with variable nanostructure, surface chemistry and textural properties, thereby effectively tuning the material activity for the methanation of pre-adsorbed CO2. The materials were thoroughly characterized and evaluated during the integrated CO2 capture and methanation process. It was found that the Pechini sol-gel synthesis method led to the structure with the highest porosity, basic site population and high dispersion of methanation and adsorption active Ru0 and Al-O--Na+ sites. The corresponding material displayed the highest CH4 yield (0.47 mmol/g) and fastest CH4 production kinetics, while stable performance was achieved under successive adsorption-hydrogenation cycles and under the co-presence of O2 and H2O during CO2 adsorption. Lastly, the increase in Ru load (0.25 wt% - 4 wt% range) could incrementally improve the CH4 production kinetics during hydrogenation.

Combination of linear solvation energy and linear free-energy relationships to aid the prediction of reaction kinetics: Application to the solvolysis of 5-HMF by alcohol to levulinate

In the context of cellulose valorization, we studied the kinetics of levulinates synthesis via the solvolysis of 5-HMF by alcohol over Amberlite IR-120. The alcohol plays a double role; it is a reactant and acts as the solvent. In the literature, kinetic models were developed for each type of alcohol, but there were no models combining the dual effect of alcohol alkyl group substituent (ROH) as a reactant and solvent. Such global kinetic models can save time and optimize a process by considering the solvent effect. This effect was taken into account via the Kamlet–Abboud–Taft and Taft equations, using Bayesian inference. We studied the kinetics of levulinate production from 5-HMF in a reaction mixture made of alcohol and GVL within a temperature range from 80 to 115 °C. The following alcohols were used: methanol, ethanol, propanol, butanol, pentanol, and hexanol. It was found that the rate of alkyl levulinate production increases faster in alcohol reaction medium compared to water reaction medium, and increases when increasing the alkyl group substitution (rMLMethanol>rELEthanol>rPLPropanol>rBLButanol>rPeLPentanol>rHeLHexanol>rLAWater). Among the global kinetic models developed in this study, the one that neglects the side reaction of humins was found to be the most reliable.

Biogas Production from the Potato Peel Waste: Study of the Effect of C/N Ratio, EM-4 Bacteria Addition and Initial PH

Objective: The objective of this study was to examine the effect of the C/N ratio, EM-4 addition and initial pH on the yield of biogas from potato peels. Theoretical Framework: In this topic, the concept and theory of biogas production from potato peels on a laboratory scale is presented, then the best conditions and kinetic constants are studied using the Gompertz model. Method: The variables in this study were the C/N ratio of 25 and 30, the EM-4 addition of 10%v/v, and initial pH of 6.8 and 7. This research was conducted on laboratory scale digesters under batch system. This study also discussed the kinetics of biogas production using the modified Gompertz model. Results and Discussion: The results showed that the C/N ratio of 30 produced a more biogas yield 17.6-26.1% compared to the C/N ratio of 25. The addition of EM-4 bacteria resulted in a more biogas yield 17.8-23.4% compared to the without addition case. The initial pH of 7 resulted in a more biogas yield 26-29% compared to the initial pH of 6.8. In kinetic analysis, the C/N ratio of 30, with EM-4 addition of 10% and initial pH of 7 resulted the greatest values of the maximum biogas production (A) which was 6,570.24 mL/grTS and the biogas production rate (U) which was 168.56 mL/grTS.day and resulted the lowest value of the minimal biogas formation (λ) which was 13.69 days, with R2 = 0.998. Research Implications: The practical and theoretical implications of this research are discussed, providing insight into how the results can be applied or influence practice in the field of renewable energy in the form of biogas from potato peels. Originality/Value: This research contributes to the literature by presenting the concept of biogas production using potato peel as raw material. The relevance and value of this research is proven by the C/N ratio, EM-4 bacteria and pH were proven to increase the productivity of biogas from waste potato peel.