Artículos científicos

THE AIM OF THIS STUDY IS TO DETERMINE AND COMPARE THE LEVELS OF PROFESSIONAL IDENTITY OF FUTURE TEACHERS FROM THREE CHILEAN UNIVERSITIES, ACCORDING TO THEIR ACADEMIC PROGRESSION, AND TO CHARACTERISE THEIR PROFESSIONAL IDENTITY BASED ON THEIR SUBJECTIVE THEORIES. A MIXED SEQUENTIAL STUDY WAS CARRIED OUT, IN WHICH 662 FUTURE TEACHERS FROM THREE CHILEAN UNIVERSITIES TOOK PART. A SCALE OF TEACHER PROFESSIONAL IDENTITY, SOCIODEMOGRAPHIC SURVEY AND EPISODIC INTERVIEWS WERE APPLIED. THE QUANTITATIVE ANALYSIS WAS CARRIED OUT WITH SPEARMAN?S CORRELATION AND THE KRUSKALL WALLIS TEST TO COMPARE THE PROFESSIONAL IDENTITY ACCORDING TO THE LEVEL OF THE FUTURE TEACHERS. FOR THE QUALITATIVE ANALYSIS, GROUNDED THEORY WAS APPLIED. SIGNIFICANT DIFFERENCES WERE FOUND IN THE LEVELS OF PROFESSIONAL IDENTITY WHEN COMPARING THE FIRST, THIRD, FOURTH AND FIFTH YEARS, AND SUBJECTIVE THEORIES THAT EXPLAIN THESE DIFFERENCES. A COMPREHENSIVE MODEL WAS DEVELOPED, WHERE THE COMPLEXITY OF SUBJECTIVE THEORIES AND PROFESSIONAL KNOWLEDGE ACQUIRED IN PROFESSIONAL PRACTICE EXPLAIN THE DECLINE IN PROFESSIONAL IDENTITY IN RECENT YEARS. IN THE DISCUSSION, THE RESULTS ARE ANALYZED FROM THE LITERATURE AND IT IS RECOMMENDED TO APPROACH THE CONSTRUCTION OF THE PROFESSIONAL TEACHER IDENTITY SYSTEMATICALLY AND IN A PLANNED MANNER DURING INITIAL TRAINING.

THE AIM OF THIS STUDY IS TO EVALUATE THE PSYCHOMETRIC PROPERTIES AND FACTORIAL INVARIANCE OF THE CLIMATE CHANGE ATTITUDE SCALE (CCAS). BASED ON PLANNED BEHAVIOR THEORY, THE SCALE MEASURES BOTH BELIEFS AND BEHAVIORAL INTENTIONS TOWARDS CLIMATE CHANGE. THE ORIGINAL INSTRUMENT CONSISTS OF 15 ITEMS, USING A FIVE-POINT LIKERT RESPONSE FORMAT. IT WAS APPLIED TO A NON PROBABILISTIC SAMPLE OF 800 CHILEAN PARTICIPANTS. AFTER TRANSLATION AND REVIEW, THE SCALE DEMONSTRATED ADEQUATE CONTENT VALIDITY. A CONFIRMATORY FACTOR ANALYSIS (CFA) VALIDATED THE INSTRUMENT

WE INVESTIGATE THE SENSITIVITY OF HOUSEHOLDS TO SUBSIDY AMOUNTS FOR PROPOSED INVESTMENTS IN A SOLAR LIGHTING SYSTEM OR A CONNECTION TO THE ELECTRICITY GRID. USING A LARGE MICRODATA SAMPLE OF 15,930 HOUSEHOLDS FOR A GROUP OF 12 DEVELOPING COUNTRIES, THE RESULTS SHOW THAT HAVING A FORMAL BANK ACCOUNT SIGNIFICANTLY INFLUENCES THE WILLINGNESS TO PAY FOR A SOLAR LIGHTING SYSTEM OR FOR GRID ACCESS, BUT THIS EFFECT DIMINISHES WITH DELAYED PAYMENT OPTIONS. ECONOMICALLY CONSTRAINED HOUSEHOLDS, SUCH AS THOSE WITHOUT A FORMAL BANK ACCOUNT, ARE NOT SENSITIVE TO SUBSIDIES FOR SOLAR LIGHTING SYSTEMS, WHICH MAY BE TOO EXPENSIVE, BUT THEY ARE SENSITIVE TO SUBSIDIES FOR CHEAPER INVESTMENTS. OUR INTERACTION ANALYSIS REVEALS THAT HOUSEHOLDS WITHOUT A BANK ACCOUNT (AND THUS CONSTRAINED BY FINANCIAL CONDITIONS) WHO ARE OFFERED AN INVESTMENT WITH A 66 % SUBSIDY ARE MORE LIKELY TO BE WILLING TO PAY THAN ARE THOSE HOUSEHOLDS WITH A BANK ACCOUNT AND WHO RECEIVE A FULL PRICE OFFER WITHOUT ANY SUBSIDIES. WE CAN THEN CALCULATE EQUITABLE SUBSIDY AMOUNTS, WHICH WE NORMATIVELY DEFINE AS THE AMOUNTS NECESSARY TO GIVE EACH HOUSEHOLD AN EQUAL PROBABILITY OF BEING WILLING TO PAY THE UPFRONT COST. FOR EXAMPLE, WHEN THERE ARE NO SUBSIDIES FOR HOUSEHOLDS WITH A FORMAL BANK ACCOUNT, EQUITABLE SUBSIDY AMOUNTS FOR HOUSEHOLDS WITHOUT A FORMAL BANK ACCOUNT ARE APPROXIMATELY 43 % FOR A SOLAR LIGHTING SYSTEM AND 65 % FOR A GRID CONNECTION.

THIS STUDY OPTIMIZES THE PRODUCTION OF ACTIVATED CARBONS FROM HYDROTHERMALLY CARBONIZED (HTC) BIOMASS USING POTASSIUM HYDROXIDE (KOH) AND PHOSPHORIC ACID (H3PO4) AS ACTIVATING AGENTS. A 23 FACTORIAL EXPERIMENTAL DESIGN EVALUATED THE EFFECTS OF AGENT-TO-PRECURSOR RATIO, DRY IMPREGNATION TIME, AND ACTIVATION DURATION ON MASS YIELD AND IODINE ADSORPTION CAPACITY. KOH-ACTIVATED CARBONS ACHIEVED SUPERIOR IODINE NUMBERS (UP TO 1289 MG/G) BUT LOWER MASS YIELDS (18?35%), REFLECTING ENHANCED POROSITY AT THE COST OF MATERIAL LOSS. CONVERSELY, H3PO4 ACTIVATION YIELDED HIGHER MASS RETENTION (UP TO 54.86%) WITH MODERATE IODINE NUMBERS (UP TO 1117.3 MG/G), BALANCING POROSITY AND YIELD. HTC PRETREATMENT AT 190 °C REDUCED THE ASH CONTENT, THEREBY ENHANCING THE STABILITY OF HYDROCHAR. THESE FINDINGS HIGHLIGHT THE TRADE-OFFS BETWEEN ADSORPTION PERFORMANCE AND PROCESS EFFICIENCY, WITH KOH SUITED FOR HIGH-POROSITY APPLICATIONS (E.G., WATER PURIFICATION) AND H3PO4 FOR INDUSTRIAL SCALABILITY. THE STUDY ADVANCES BIOMASS WASTE VALORIZATION, ALIGNING WITH CIRCULAR ECONOMY PRINCIPLES AND OFFERING SUSTAINABLE SOLUTIONS FOR ENVIRONMENTAL AND INDUSTRIAL APPLICATIONS, SUCH AS WATER PURIFICATION AND ENERGY STORAGE.

BIOMASS PYROLYSIS STANDS OUT AMONG BIOMASS RECOVERY TECHNOLOGIES DUE TO ITS POTENTIAL TO OBTAIN VALUE-ADDED COMPOUNDS. HOWEVER, ITS LIQUID PRODUCT PRESENTS MANY OXYGENATED COMPOUNDS THAT REDUCE ITS CHEMICAL STABILITY. THIS STUDY AIMED TO EVALUATE ZINC AND GALLIUM SUPPORTED ON CHILEAN NATURAL ZEOLITE (NZ) AS A CATALYST IN THE HYDROPYROLYSIS OF LIGNOCELLULOSIC BIOMASS TO DRIVE THE FORMATION OF MONOAROMATIC (MAH) COMPOUNDS THROUGH HYDRODEOXYGENATION REACTIONS (HDO). THE BIOMASS TO BE RECOVERED WAS CHILEAN OAK, WHICH WAS SUBJECTED TO TORREFACTION TREATMENTS AND CHARACTERIZED THROUGH VARIOUS ANALYSES. THE NATURAL ZEOLITE WAS MODIFIED USING ION EXCHANGE TREATMENTS TO (I) REMOVE ITS COMPENSATING CATIONS AND INCREASE ACIDITY, AND (II) LOAD GA AND ZN AT 2% AND 5%. CATALYTIC HYDROPYROLYSIS TESTS WERE PERFORMED IN AN ANALYTICAL PYROLYSIS SYSTEM (PY-GC/MS). THE FIBER ANALYSIS OF THE BIOMASS REVEALED THAT HEMICELLULOSE CONTENT DECREASED WHILE LIGNIN CONTENT INCREASED, RESULTING IN HIGHER ENERGY DENSITY AND LOWER OXYGEN LEVELS. THE PROXIMATE AND ULTIMATE ANALYSES CONFIRMED THESE FINDINGS. ON THE OTHER HAND, NATURAL ZEOLITE MAINTAINED ITS CRYSTALLINE PROPERTIES EVEN AFTER MODIFICATION, AND THE METAL NANOPARTICLES WERE SMALLER THAN 5 NM. THE SUPPORTED METALS WERE IN THEIR OXIDIZED STATE TO PROMOTE SURFACE ACIDITY. THE GA3+ CATALYSTS WERE ABLE TO FORM UP TO 35% PHENOLS, 27% KETONES, AND 10% MAH, WHILE THE ZN2+ CATALYSTS FORMED UP TO 34% MAH, 24% KETONES, 17% FURANS, AND 13% PHENOLS. THE KEY FACTORS BEHIND ZN?S EFFECTIVENESS WERE THE LEWIS ACID SITES THAT COULD ACTIVATE C?O BONDS AND ENCOURAGE HDO REACTIONS, MAKING IT A PROMISING CATALYST.