bluuebunny/crossref_metadata_2025 huggingface dataset:
PENGEMBANGAN LKS PEMBELAJARAN BERBASIS MASALAH UNTUK MENINGKATKAN KETRAMPILAN BERPIKIR KRITIS DAN MINAT BELAJAR SISWA PADA MATERI FLUIDA STATIS DI SMA N 1 SAMUDERA ACEH UTARA
Authors: Nizarullah Muhammad , Yusrizal Yusrizal , Halim A.
Published: April 2018

Abstrak. Penelitian ini bertujuan mengetahui peningkatan berpikir kritis siswa dan peningkatan minat belajarnya melalui pengembangan LKS berbasis masalah pada materi fluida statis. Penelitian ini mengunakan pendekatan penelitian research and development (RD). Pengembangan dilakukan dengan mengacu pada model 4-D dengan tahapan definition, design, development, dan dissemination. Penelitian ini dilakukan dengan metode quasi experimental melalui the matching-only pretest-posttest control group design. Pemilihan sampel menggunakan teknik purposive sampling yaitu kelas X-MIPA1 sebagai kelas eksperimen yang diajarkan dengan LKS berbasis masalah dan X-MIPA2 sebagai kelas kontrol. Pengumpulan data dilakukan dengan pretest, posttest dan N-gain untuk mengetahui peningkatan hasil belajar siswa, lembar observasi untuk mengetahui ketrampilan berpikir kritis siswa dan angket untuk mengetahui minat siswa. Hasil uji N-gain kelas eksperimen mengalami peningkatan hasil belajar sebesar 0,7 (70%) berada dalam kategori “tinggi”, sedangkan kelas kontrol mengalami peningkatan hasil belajar sebesar 0,42 (42%) berada dalam kategori “sedang”. Hasil uji homogenitas dan normalitas menunjukkan data berdistribusi homogen dan normal, maka dilakukan uji-t (two independent sample t-test) pada taraf signifikan 0,05 dengan dengan derajat kebebasan 53, diperoleh Thitung Ttabel, jadi dapat disimpulkan terdapat perbedaan yang signifikan terhadap peningkatan ketrampilan berpikir kritis antara kelompok. Hal ini menunjukkan peningkatan ketrampilan berpikir kritis kelas eksperimen lebih tinggi dibandingkan dengan kelas kontrol. Hasil analisis angket minat siswa menunjukkan bahwa LKS berbasis masalah yang dikembangkan dapat meningkatkan minat belajar siswa.Kata Kunci:  LKS berbasis Masalah, Berpikir kritis, Minat belajar.
PERBANDINGAN DAYA SERAP SERBUK GERGAJI KAYU DAMAR LAUT (SHOREA SP) DAN MERBAU (INTSIA SP) TERHADAP LOGAM Pb(II)
Authors: Khaldun Ibnu , Aristia Aristia , Sarah Faucut
Published: April 2018

Abstrak. Penelitian ini bertujuan untuk  menginvestigasi kemampuan daya serap serbuk gergaji kayu damar laut (Shorea sp) dan merbau (Intsia sp) terhadap logam Pb(II) dari larutan, dan mempelajari pengaruh kondisi percobaan seperti pH larutan, waktu kontak, jumlah adsorben dan konsentrasi adsorbat. Efisiensi adsorpsi maksimum  berturut-turut sebanyak 95,72% pada pH 4 dan 98,78% pada pH 5 oleh damar laut (Shorea sp) dan   kayu merbau (Intsia sp). Adsorpsi timbal oleh kedua adsorben meningkat dengan bertambahnya waktu dan pH (dari 1 hingga 5) dan menurun dengan menurunnya kekuatan ion. Data kesetimbangan dikorelasikan dengan isotherm Langmuir dan Freundlich. Kapasitas adsorpsi maksimum berdasarkan isotherm Langmuir untuk serbuk kayu damar laut dan kayu merbau berturut-turut sebesar 45,45 mg/g dan 14,706 mg/g dan berdasarkan isotherm Freundlich sebesar untuk serbuk kayu damar laut dan kayu merbau berturut-turut sebesar 1,2475 mg/g dan 1,616 mg/g. Dari hasil tersebut disimpulkan bahwa model Langmuir adalah yang terbaik.Kata kunci: Adsorpsi, damar laut, merbau, isotherm, serbuk gergaji. Abstract. The aim of this work is to investigate the performance of damar laut (Shorea sp) and  merbau (Intsia sp) sawdust  for the adsorption of  lead(II) from aqueous solutions, and to study the influence of the operating conditions such as solution pH, contact time, amount of adsorbent, and concentration of adsorbate.  The maximum adsorpsi efﬁciencies were 95.72% for damar laut (Shorea sp) at pH 4 and  98.78% for  kayu merbau (Intsia sp) at pH 5.  The adsorption  of lead by both sorbents increased with an increase in contact time and pH (from 1 to 5) and decreased with an increase in ionic strength. The equilibrium data has been correlated with both Langmuir and Freundlich isotherms.  The maximum adsorption capacity of the sawdust evaluated by Langmuir adsorption model  by damar laut (Shorea sp) and  merbau (Intsia sp) sawdust was 45.45 mg/g and 14.706 mg/g respectively and by Freundlich adsorption model by damar laut (Shorea sp) and  merbau (Intsia sp) sawdust was 1.2473 mg/g and 1.616 mg/g respectively. The results indicate that the Langmuir model fits the data better.Keywords: adsorption, Shorea sp, Intsia sp, Isotherms, Sawdust.
KELAYAKAN MEDIA ANIMASI HUKUM NEWTON II TENTANG GERAK PADA BIDANG MIRING DAN KATROL DI SMA KABUPATEN ACEH BESAR
Authors: Muslina Muslina , Halim Abdul , Khaldun Ibnu
Published: April 2018

Abstrak. Penelitian ini dilakukan untuk mengembangkan media animasi hukum Newton II tentang gerak pada bidang miring dan katrol, mendeskripsikan kelayakan media animasi hukum Newton II yang dikembangkan baik dari segi kualitas, validitas, berdasarkan masukan para ahli, meminta tanggapan guru dan siswa terhadap media sehingga layak digunakan dalam pembelajaran fisika. Penelitian dilakukan di tiga sekolah kabupaten Aceh Besar (SMAN Modal Bangsa, SMAN 1 Montasik,  dan SMAN 1 Krueng Barona Jaya) menggunakan metode penelitian reasearch and development (R and D) dengan model pengembangan ADDIE.  Hasil pengujian alfa test  menunjukkan bahwa media animasi hukum Newton II tentang gerak pada bidang miring dan katrol sangat baik/layak digunakan sebagai media dari segi validitas. Penilaian kualitas media  dari aspek perangkat lunak, desain pembelajaran, desain media dan aspek komunikasi  secara keseluruhan menunjukkan bahwa media mempunyai kriteria sangat baik dan layak digunakan. Pengujian beta testing yang didasarkan pada hasil uji/tanggapan pengguna oleh guru dan siswa secara keseluruhan memberikan respon positif terhadap media, sehingga media animasi hukum Newton II yang dikembangkan memiliki kriteria sangat baik. Dari hasil penelitian  didapat bahwa kualitas media animasi yang dikembangkan memenuhi kriteria sangat baik dan layak digunakan sebagai media yang menunjang proses pembelajaran fisika. Kata Kunci : Media, Animasi, Katrol, Bidang Miring,Alfa test, Beta TestAbstract. This research was conducted to develop animation media Newton's second law of motion on an incline and pulley, describes eligibility animation media Newton's second law developed both in terms of quality, validity based on the input of experts, asking for a response of teachers and students to the media so it's worth used in learning physics. The study was conducted in three school districts of Aceh Besar (SMAN Modal Bangsa, SMAN 1 Montasik and SMAN 1 Krueng Barona Jaya) using research methods reasearch and development (R and D) with ADDIE development model. The test results showed that the alpha test animation media Newton's second law of motion on an incline and pulley very good / decent used as a medium in terms of validity. Quality assessment of aspects of the software media, instructional design, media design and communication aspects of the overall show that the media has a very good criteria and fit for use. Testing beta testing based on the test results / user feedback by teachers and students as a whole give a positive response to the media, so the media animation Newton's second law which has developed criteria very well. The result is that the quality of animation media which meet the criteria developed very well and fit for use as a media that support the learning process of physics.Keywords: Media, Animation, Pulleys, Field Leaning, Alpha Test, Beta Test
PERANGKAT PEMBELAJARAN IPA BERBASIS INKUIRI TERBIMBING DENGAN TUGAS PROYEK MATERI SISTEM EKSKRESI UNTUK MENUNTASKAN HASIL BELAJAR SISWA SMP
Authors: Baharuddin Baharuddin , Indana Sifak , Koestiari Toeti
Published: April 2018

Abstract. This research purposed to produce science learning materials that eligible to complete student learning achievement at junior high school of the System of Excretion materials. The development of this learning tool based on Dick and Carey model and the using test based One Group Pretest-Posttest Design. The test conducted in eighth grade student of SMP Negeri 16 Poleang Tengah. This research consisted of two stages: 1) Developing the learning materials consisted of lesson plan, student’s book, and student’s worksheet, and learning achievement test validated by experts. 2) Implementation of the validated learning materials which instrument that used in this research are validation sheet, observational sheet of learning accomplishment, the learning constraints, observational sheet of student’s activity, and Student’s response questionnaire. The result showed that: 1) The learning materials were valid; 2) the lesson plan accomplishment was categorized as good; 3) The student activities indicated that they learn to actively build their own knowledge through a process of inquiry; 4) The students responded positively to the learning process; 5) The student’s learning achievements of attitude, knowledge, and skill aspects were accomplished. Based on the following results can be concluded that the science learning materials based on guided inquiry with a project task on Excretion of System were valid, practical, and effective. Thus the science learning materials can be used on the learning process and proofed to be effective to complete student’s learning achievement.Keywords: Guided inquiry, project task, completeness of student’s, excretion system.
СОСТОЯНИЕ СУДЕБНО-МЕДИЦИНСКОЙ ЭКСПЕРТИЗЫ КАК ИНДИКАТОР СТЕПЕНИ ЗАЩИЩЕННОСТИ СОЦИУМА ОТ БИОТЕРРОРИЗМА
Authors: Ковалев А.В. , Владимиров В.Ю. , Савчук С.А. , Романенко Г.Х.
Published: April 2018

В статье подчеркивается значимость судебно-экспертной профилактики преступлений против безопасности государства и личности. Приводится пример использования материала судебно-медицинской экспертной деятельности для построения криминалистической характеристики преступлений, связанных с незаконным оборотом новых психоактивных веществ в различных регионах Российской Федерации и возникновением в результате их потребления массовых отравлений. Делается вывод о необходимости корректировки действующего законодательства и выработке более эффективных мер защиты государства и личности от гибридных средств поражения.
Development of Gel Dossage Form From Mulberry Fruit Extract as A Facial Treatment
Authors: Arif Dhanesh , Aulifa Diah Lia , Rahayu Driyanti , Praditasari Arni
Published: April 2018

Skin care is very important in cosmetics, especially facial treatments. Black mulberry is rich in phenols and is therefor
usable in the treatment of acne. It also contains anthocyanin, a well-known antioxidant and a potential source of sun
protection. This research aimed to develop a gel dossage from black mulberries (Morus nigra) extracts that would function
as an antibacterial, antioxidant and sun blocking facial treatment. This research started with black mulberry fruit extracted
through the maceration method by using ethanol (96%). Then, the antibacterial activity of the extract was determined by
the disc-diffusion method, while the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration
(MBC) were determined by the microdilution method. Antioxidant activity of the extract was determined using the 1,1-
diphenyl-2-picrilhidrazil (DPPH) method with vitamin C as a comparison. Furthermore, the extracts were formulated into
gel formulas with variations of HPMC, Na-CMC, carbopol 934 and extract concentrations. The products were then
physically evaluated for organoleptics, homogeneity, pH, viscosity, and dispersion as well as undergoing a hedonic test,
an irritation test, an antioxidant activity test and determining the SPF value of the preparation. The results showed that the
black mulberry fruit extract has antibacterial activity with MIC value of 0,025 g/mL against S. epidermidis and P. acnes,
while MBC values were 0,025 g/mL and 0,05 g/mL, respectively. The black mulberry extract had antioxidant activity with
IC50 value, i.e 146,73 μg/mL vitamin c i.e. 3,17 μg/mL. Formulation with best physical evaluation results showed ina
formula containing a carbopol gel base of 934 0,015 g/mL with an extract cconcentration of 0,075 g/mL. This formula
resulted in antioxidant activity with an IC50 value, i.e 1004,6 μg/mL, antibacterial activity with inhibition zone 6.83 ± 1.4
mm against and 6.76 ± 0.9 mm against S. epidermidis and P. acnes respectively and an SPF value of 1.9.
Türkiye’de Yenilenebilir Enerji Üretimi ve Ekonomik Büyüme İlişkisi Üzerine Ampirik Bulgular
Authors: ERDOĞAN Selim , DÜCAN Engin , ŞENTÜRK Mehmet , ŞENTÜRK Aslı
Published: April 2018

Geleneksel enerji kaynaklarının arz
güvenliği endişeleri ve çevresel etkileri nedeniyle yenilenebilir enerji her
geçen gün biraz daha önem kazanmaktadır. Öyle ki, fosil kaynaklara sahip
ülkeler dahi gelecek yıllarda mevcut ekonomik statülerini sürdürebilmek
amacıyla yenilenebilir enerji kaynaklarına yatırım yapmaktadırlar. Şüphesiz bu
yatırımlar ülkelerin ekonomik büyüme performansları üzerinde etkili olmaktadır.
Bu çalışmada, Türkiye’de yenilenebilir enerji üretimi (YEN) ile ekonomik büyüme
(GSYH) arasındaki ilişki Johansen Eşbütünleşme Testi ve VECM nedenselliği ile
sorgulanmıştır. Sonuç olarak, ekonomik büyümenin yenilenebilir enerji
üretiminin uzun dönemde nedeni olduğu ve bu iki değişkenin eşbütünleşik
oldukları tepit edilmiştir.
Crescimento da literatura sobre bibliometria, informetria e cientometria no Brasil
Authors: Urbizagastegui Ruben , Restrepo-Arango Cristina
Published: April 2018

Analiza el crecimiento de la literatura sobre bibliometría publicada en el Brasil por autores brasileños o extranjeros en la forma de artículos de revistas, capítulos de libros y trabajos presentados en congresos. Analiza el crecimiento de la literatura publicada por trienios, la forma y la tasa de crecimiento, así como el periodo de duplicación de esta literatura. Se encontraron 2300 documentos que fueron publicados desde 1973 hasta diciembre de 2012. Esta literatura crece de forma exponencial, a una tasa de 24% al año y se duplica aproximadamente cada 3.2 años.
Mediação na Ciência da Informação: uma análise bibliométrica na coleção Benancib
Authors: Farias Maria Giovanna Guedes , Farias Gabriela Belmont de
Published: April 2018

Trata-se de pesquisa realizada na coleção Benancib depositada no repositório Questões em Rede, a qual disponibiliza a produção científica do Enancib. O objetivo se concentrou em descobrir o que os pesquisadores da Ciência da Informação (CI) vêm investigando sobre mediação num lapso de tempo de dez anos. Para isso, analisou-se a recorrência do termo mediação no campo de pesquisa título da coleção, averiguando quais autores e instituições mais publicaram e as temáticas mais recorrentes. Os procedimentos metodológicos se caracterizam pela abordagem quanti-quali, com ênfase no método bibliométrico, de natureza exploratória e descritiva, com foco na observação, registro, classificação e análise dos dados. Os resultados demostram que os estudiosos da CI vêm pesquisando os processos mediacionais e sua influência na atuação do mediador junto aos usuários em ambientes diversos de informação. Para que essa investigação ocorra, os pesquisadores recorrem à teorização da mediação a partir dos conceitos de diferentes áreas do conhecimento, a exemplo da comunicação, educação, filosofia e antropologia. Conclui-se que, a partir desta análise é possível entender os caminhos percorridos pela mediação da informação como aporte conceitual e pragmático ligada a objetos diversos na nossa área, durante um considerável período de tempo.
Os repositórios das universidades federais do Brasil e suas políticas de informação
Authors: Baggio Claudia Carmem , Blattmann Ursula
Published: April 2018

Esta pesquisa tem por objetivo a identificação das políticas implantadas nos repositórios das 63 Universidades Federais do Brasil onde se pôde compreender a importância de fomentar mecanismos para dar visibilidade à produção acadêmica. Utiliza a pesquisa documental como método de coleta de dados nos repositórios institucionais selecionados. Foram selecionados para análise aqueles que contemplam em todo seu escopo aspectos organizacionais, técnicos e legais ou que possuam características de um programa de preservação digital. Entre os resultados destacam-se as 20 IFES que possuem políticas de informação instituídas e disponibilizadas nos seus Websites. A conclusão possibilita oferecer subsídios aos dirigentes dos repositórios para construção de políticas de informação, estas políticas facilitam a organização e a disseminação da informação, o que traz benefícios tanto para a comunidade científica e institucional quanto para a sociedade de um modo geral.
Adestrando o elefante: uma abordagem ortodoxa do Princípio da Proveniência
Authors: Horsman Peter
Published: April 2018

O princípio da proveniência está no cerne da prática e da teoria arquivística. Mas o que esse princípio significa e como deve ser interpretado? É amplamente aceito pela comunidade arquivística que um fundo de arquivo deve ser mantido como um todo, no entanto, a interpretação de que o arranjo original deve ser preservado, e eventualmente reconstituído, está aberta ao debate. Este artigo, publicado originalmente nos anos 1990, explica os principais argumentos para esse debate e apresenta novas interpretações para os arquivos criados no século XX, propiciando uma reflexão atual também no que concerne aos documentos arquivísticos produzidos em ambiente digital, afirmando que o princípio é sobre o respeito ao contexto de criação e arquivamento.
Objetos de Aprendizagem para o Letramento Informacional
Authors: Gasque Kelley Cristine Gonçalves Dias
Published: April 2018

Apresenta fundamentos básicos para a produção de objetos de aprendizagem (OAs), bem como resultado de pesquisa exploratória sobre a percepção de estudantes sobre a produção dos referidos recursos. A produção dos OAs requer conhecimentos que envolvem questões de conteúdo, de ensino-aprendizagem e conhecimentos técnicos. Os resultados mostram que os sujeitos reconhecem a importância dos objetos de aprendizagem para potencializar o processo de ensino-aprendizagem e demonstram disposição e motivação no processo de produção, mas também ressaltam a necessidade de melhorar a interface dos softwares para torná-la mais amigável e intuitiva.
Використання в будівництві теплоефективної порожнотілої кераміки та пористих бетонів
Authors: Nedbailo O.M. , Chernyshyn O.G.
Published: April 2018

Розглянуті деякі науково-технічні аспекти проблеми ресурсозбереження при масовому будівництві та експлуатації енергоефективних (опалюваних) будівельних об’єктів. Звертається увага на необхідність використання виробів із пористих бетонів, насамперед із автоклавного ніздрюватого бетону й гідрофобізованого цементного  перлітобетону.

У результаті теоретичного аналізу встановлено, що міцність пористих композиційних матеріалів будівель- ного призначення із ніздрюватою або зернистою структурою суттєво залежить від факторів у вигляді певних функцій або параметрів.

Встановлено, що активована цементна суміш містить дисперговані частинки клінкера зі зменшеним у 1,4 – 1,5 рази електрокінетичним потенціалом, що сприяє формуванню більш щільної та міцної зі зменшеною усад- кою структури цементного каменя. Недоліком пресової технології є неможливість виробництва виробів з різни- ми розмірами та необхідність застосування дефіцитного волокнистого заповнювача при виготовленні теплоізоляційних плит. Ввідомо, що теплоізоляційний цементний перлітобетон в порівнянні з теплоізоляційним газобетоном має покращені фізико-технічні властивості (зменшену теплопровідність, відкриту пористість, усадку при висиханні, анізотропію міцності, підвищену міцність при стиску та однорідність середньої густини, регульова- ну сорбційну вологість), що дозволяє ефективно застосовувати його як теплоізоляційний шар огороджувальних конструкцій.
Аналіз плину цементно-піщаного розчину при віброекструзійному способі виготовлення фібробетонних виробів
Authors: Andreev I.A. , Smirnova К.O.
Published: April 2018

Запропонований метод опису ізотермічного ламінарного усталеного плину нестисливої ньютонівської рідини у збіжних пірамідальних каналах квадратного поперечного перерізу, який дозволяє здійснювати розрахунки дозатора-живильника розчину віброекструзійної установки.

Для вдосконалення формування тонкого шару розчину були запропоновані конструкції дозаторів-живильни- ків, які виключають утворення застійних зон і забезпечують отримання джгутів цементно-піщаного розчину зі стабільними формою і якістю. Подача розчину на транспортер при цьому здійснюється через квадратні у попе- речному перерізі збіжні канали. Аналітичних формул для опису плину у таких каналах не існує.
Chromatin Bound PCNA is Complexed with Cell Cycle Protein Regulators as Determined by Chromatin Immunoprecipitation
Authors: Becerril Nazul , Martínez Miguel Ángel , García Elpidio , Vázquez Ramos Jorge Manuel
Published: April 2018

Using the technique of Chromatin Immunoprecipitation, we have detected the formation of complexes between the homotrimer protein ring Proliferating Cell Nuclear Antigen, PCNA, and two fundamental regulators of the cell cycle, CdkA and Cyclin D4;2 along germination of maize seeds. This finding suggests the way PCNA participates in the control of the G1 phase, by allowing cyclin-kinase complexes to find and phosphorylate protein targets. Incidentally, PCNA may form a structure of a dimer of trimer when bound to the chromatin.
Sanguinarine and Dihydrosanguinarine Accumulation in Argemone mexicana (L) Cell Suspension Cultures Exposed to Yeast Extract
Authors: Guízar-González Cecilia , Trujillo-Villanueva Karen , Monforte-González Miriam , Vázquez-Flota Felipe
Published: April 2018

Alkaloid contents in Argemone mexicana cell line AMMiF were analyzed during a 36-day culture cycle. The benzophenanthridine sanguinarine (SA) represented the main alkaloid. Dihydrosanguinarine (DHSA), a SA biosynthetic precursor and a less toxic benzophenanthridine, was also identified, based on chromatographic properties and further confirmed by gas chromatography coupled to mass spectrometry. Along the culture cycle, SA contents increased simultaneously while DHSA decrease, suggesting their biosynthetic conversion. Upon exposure to yeast extract as an inducer of secondary metabolism, there was an increase in SA content, which was preceded by DHS accumulation. However, after a long exposure (72 h), contents of both SA and DHSA were noticeable elevated, with close to 20% of the total alkaloid produced being recovered from the external medium. These results suggest the operation of a cell mechanism to avoid damage inflicted by the excessive accumulation of SA.
Metal Binding Sites in Plant Soluble Inorganic Pyrophosphatases. An Example of the Use of ROSETTA Design and Hidden Markov Models to Guide the Homology Modeling of Proteins
Authors: Rosales-León Luis Rosales-León , Hernández-Domínguez Eric Edmundo , Gaytán-Mondragón Samantha , Rodríguez-Sotres Rogelio
Published: April 2018

In contrast to their counterparts in bacteria and animals the soluble inorganic pyrophosphatases from plant cells are active as monomers. The isoforms 1 and 4 from Arabidopsis thaliana have been characterized with more detail, but their three-dimensional structure is unavailable. Here, a recently published protocol (ROSETTA design-HMMer), is used to guide well-known techniques for homology-modeling, in the production of reliable models for the three-dimensional structure of these two arabidopsis isoforms. Their interaction with magnesium ions and pyrophosphate is analyzed in silicoin silico.
Oxidized Glutathione Promotes the Association of Proteins from Bean Seeds to Potato Starch
Authors: Correa Paola , Bernal Lilia , Coello Patricia , Martínez-Barajas Eleazar
Published: April 2018

In this paper, we report the use of oxidized glutathione (GSSG) in promoting the association of bean seed proteins to starch granules purified from potato tubers. The resulting interaction was stable and only a small fraction of the bound proteins was released by washing with 5% glucose. Higher concentrations of glucose or other sugars (fructose, mannose and mannitol) failed to further increase protein release. Dithiothreitol (DTT) at concentrations up to 50 mM did not liberate the proteins associated to starch; however, applied after GSSG but before adding the proteins, it was very effective in preventing binding of proteins to starch. Lastly, starch modified by the bound proteins increased its water absorption capacity.
Molecular Biology of Chili Pepper Anthocyanin Biosynthesis
Authors: Aza-González César , Núñez-Palenius Héctor Gordon , Ochoa-Alejo Neftalí
Published: April 2018

Chili pepper (Capsicum spp.) is an important horticultural crop worldwide. Chili pepper fruits from different Capsicum species have been highly consumed in Mexico since pre-Columbian times. Some Capsicum species synthesize and accumulate anthocyanins in different tissues and organs. Although the anthocyanin biosynthetic pathway has been established for different plant species, very few studies on anthocyanin chemistry, biochemistry and molecular biology of these pigments produced by chili peppers have been reported. In this review we describe the information on the type of anthocyanins synthesized and accumulated in chili pepper, and also on the molecular biology of the biosynthetic pathway. Additionally, we discuss the applications of current knowledge for the genetic manipulation, through genetic engineering, of this trait, and also the future anthocyanin-related research areas in Capsicum.
Sensitive spectrofluorimetric and spectrophotometric methods for determination of sparfloxacin in pharmaceuticals
Authors: Shah Jasmin , Jan M. Rasul , . Inayatullah , Shah Sultan
Published: April 2018

Two simple, sensitive and accurate spectrofluorimetric and spectrophotometric methods have been developed for the determination of sparfloxacin in bulk and pharmaceutical preparations. The proposed methods were based on oxidation of sparfloxacin with Ce (IV) in acidic medium. The spectrophotometric method involved the measurement of unconsumed Ce (IV) concentration at 315 nm. The spectrofluorimetric method based on the measurement of reduced fluorescent Ce (III) at 352 nm after excitation at 250 nm. Different variables affecting the reaction such as concentration and volume of cerium (IV), type and concentration of acidic medium, heating temperature and time were carefully studied and optimized. Under the optimum conditions, linear relationship in the range of 0.02-0.2 μg mL-1 and 0.02-0.1 μg mL-1 were obtained using spectrophotometric and spectrofluorimetric methods, respectively. No interferences were observed from the common formulations excipients present in the dosage form of the drug. The proposed methods were successfully applied to the analysis of the investigated drug in pure and pharmaceutical formulations with good accuracy and precision. The recovery percentage ranged from 93-102 ± 1.73-2.66%. The precision of the methods were good; RSD ≤ 2.55%.
Synthesis and Physico-Chemical Characterization of CeO2/ZrO2-SO42- Mixed Oxides
Authors: Hernández-Enríquez Juan Manuel , Silva-Rodrigo Rebeca , García-Alamilla Ricardo , García-Serrano Luz Arcelia , Handy Brent Edward , Cárdenas-Galindo Guadalupe , Cueto-Hernández Arturo
Published: April 2018

Environmentally friendly solid-acid catalysts CeO2/ZrO2-SO42- were prepared by the sol gel method varying CeO2 content (10, 20 and 30 wt%) and using sulfation in situ, maintaining the sulfate ions amount present in the materials at 20 wt%. ZrO2 and ZrO2-SO42- were also prepared for comparison proposes using the same synthesis method. The materials were characterized by X-ray diffraction, nitrogen physisorption, potentiometric titration with n-butylamine, decomposition of 2-propanol and n-pentane isomerization. The specific surface area of ZrO2-SO42- was high (160 m2/g) compared with the unmodified ZrO2 (80 m2/g), however this area decreased with increasing the CeO2 content (37-100 m2/g). There was no significant effect of CeO2 on the tetragonal structure of ZrO2-SO42-. The variation of acid sites amount runs parallel to the change of specific surface area. The acid sites amount decreased with increasing cerium oxide content. The decomposition of 2-propanol results fundamentally in the formation of dehydration products such as propylene and diisopropyl ether, both involving acid sites. In addition, a good performance during the n-pentane isomerization was observed for these materials. The selectivity towards isopentane reaches 84% when the Pt/CeO2/ZrO2-SO42- catalyst with the highest CeO2 content was used.
Orizabolide, a New Withanolide from Physalis orizabae
Authors: Maldonado Emma , Gutiérrez Rodrigo , Pérez-Castorena Ana L. , Martínez Mahinda
Published: April 2018

A new withanolide, orizabolide (1), together with the known flavonoid rutin (2) were isolated from the aerial parts of Physalis orizabae. Structural elucidation of these compounds was carried out by interpretation of their spectroscopic data.
Total Recovery of Gold Contained in Computer Printed Circuit Boards. Leaching Kinetics of Cu, Zn and Ni
Authors: Reyes María Isabel , Rivera Isauro , Patiño Francisco , Flores Mizraim U. , Reyes Martín
Published: April 2018

In this study a thorough characterization of certain printed circuit boards has been carried out; it was found that they are made up of a polymer layer, a metal layer of Cu, Zn and Ni, and a gold substrate. A kinetic study of the acid dynamic leaching of copper, zinc and nickel has been carried out, finding out that these elements’ dissolution allows the gold substrate to be physically separated; then, the gold particles are separated from the polymer by filtration. The reaction orders were calculated vs. H2SO4 concentration, and the activation energy was calculated as well; reaction orders of n = 0.265, n = 0.247 and n = 0.245 were found for Cu, Zn and Ni respectively, while Ea = 86.3, Ea = 95.3 and Ea = 11.2 kJ/mol were found for Cu, Zn and Ni respectively. When the attack time is over, a shiny, solid product has been obtained; it was characterized by SEM-EDS and AAS, confirming that it is metallic gold, with a purity of 100 and 99.9% according to the respective technique.
Silver Precipitation Using Sodium Dithionite in Cyanide Media
Authors: Rivera Isauro , Juárez Guillermo , Patiño Francisco , Reyes Iván A. , Roca Antonio , Reyes María I.
Published: April 2018

The nature of the reaction and the main parameters affecting Ag precipitation rate in the system Ag+-CN--S2O42- are studied. From the results obtained, a process of chemical precipitation for Ag recovery is proposed, using an environmentally-friendly reducing reagent (sodium dithionite, Na2S2O4), leaving a residual content of Ag into the permitted environmental levels (-1 Ag). The levels of CN- in liquids wastes are of the order of 0.816 mol L-1, and they can be treated by ozonization processes for inerting cyanide. The results obtained indicate that Ag precipitation is achieved in less than 1 hour, with recoveries close to 99%, at room temperature. Silver precipitation is characterized by an induction period followed by a precipitation period, leaving a metal amount in solution less than 1 mg L-1. The main kinetic parameters studied lead to obtain the following apparent reaction orders: with respect to the initial [S2O42-] was n = 1.675, with respect to [CN-] was -1.24, with respect to [OH-] was ≈0 (between 10-4 and 10-2 mol L-1) and with respect to the initial [Ag+] was 0.524. An activation energy of 77 kJ mol-1 was obtained. Under these conditions, Ag precipitation in the system Ag+-CN--S2O42- is controlled by chemical reaction, characterized by high activation energy, and is independent of the hydrodynamic variables of the system.
Effect of Solids on Gas Dispersion Characteristics: Addition of Hydrophobic and Hydrophilic Solids
Authors: Tavera F. J. , Escudero R.
Published: April 2018

There is a controversy on the role of solids in flotation systems in terms of the characteristics of the solid-liquid-gas dispersions. The effect of slurries containing carbon or silica on the characteristics of gas-slurry dispersions generated in a flotation column was studied. Experimental results suggest that hydrophilic solids prevent bubbles coalescence, and produces large bubble surface areas, available to collide and collect particles during flotation. On the other hand slurries with hydrophobic particles produce larger bubbles, affecting both the performance and the hydrodynamics of the process.
Noble Gases Encaged by the C60 Increase Their Chemical Reactivity
Authors: Cortés-Santiago Avelino , Vargas Rubicelia , Garza Jorge
Published: April 2018

In this work, we use a spherical shell with an attractive potential to simulate the C60 and its effects on, He, Ne, Ar and Kr when each atom is in the center of the sphere. Within the Kohn-Sham model, two exchange-correlation functionals were used; the main difference between these two functionals is that one incorporates explicitly the self-interaction correction and the correct asymptotic behavior of the exchange-correlation potential, and the other one does not contain such corrections. We found that the considered atoms are softer inside of the cage than when they are free. By using several chemical reactivity predictors as the electrodonating and electroaccepting powers, defined by Professor Gázquez et al. (J. Phys. Chem. A 2007, 111, 1966), it is proved that the noble gases increase their chemical reactivity when they are immersed in the C60. Naturally, this conjecture must be confirmed by more realistic models, but at first glance this is a very interesting conclusion and opens a new possibility to obtain reactions with encaged inert gases.
An Assessment of the Validity of the Maximum Hardness Principle in Chemical Reactions
Authors: Poater Jordi , Swart Marcel , Solà Miquel
Published: April 2018

We have computationally explored the fulfillment of the Maximum Hardness Principle in chemical reactions. To this end we have selected a well-defined series of 34 exothermic chemical reactions (the so-called BH76 test) and we have calculated the hardness of reactants, transition state, and products. Our results show that for only 18% of the reactions studied the hardness of the reactants is, at the same time, lower than that of the products and greater than that of the transition state, in agreement with the Maximum Hardness Principle. In most reactions we find that either the transition state has a higher hardness than the reactants or the reactants are harder that the products or both, and, therefore our results show that the Maximum Hardness Principle is disobeyed in most chemical reactions.
Application of the Active Space Self-Interaction-Correction Method to Molecular Systems
Authors: Aparicio Felipe , Garza Jorge , Galván Marcelo
Published: April 2018

Within the context of the active space of the self-interactioncorrection (SIC) optimized effective potential (OEP) method (J. Chem. Phys. 2001, 114, 639-651), the effect of the inclusion of the SIC at the level of only use the HOMO orbital is analyzed for a set of small molecules and for a model of an interstitial region surrounded by positively charged groups in a polypeptide; the model is representative of a class of regions occurring in proteins. It is shown, for the molecular systems treated in this work, that the inclusion of the HOMO orbital, within the SIC-OEP, induces a remarkable change on the eigenvalue spectrum. For the interstitial state model, the improvement is systematic as one increase the active space from one to ten orbitals; also, the influence on the local behavior of the interstitial virtual state closest to the Fermi level is important and enhances its regional character. As this method reduces the computational effort to introduce the SIC it seems promising to deal with self-interaction-corrections in systems with many atoms/electrons such as biomolecules
Elucidating the Catalytic Role of Mg(II) in the Intramolecular Proton Transfer Reaction in Thymine
Authors: Vogt-Geisse Stefan , Gutiérrez-Oliva Soledad , Herrera Bárbara , Toro-Labbé Alejandro
Published: April 2018

In the framework of the reaction force analysis a study of the mechanism of the 1-3 intramolecular proton transfer in free and Mg (II) coordinated Thymine was done in terms of the reaction electronic flux and Wiberg bond orders. Profiles of these properties evidentiated differences between the proton transfer mechanisms induced by the presence of Mg(II) cation. A significative lowering in the activation energy put forward the catalytic effect of Mg. The reaction force analysis allows a precise identification of the catalytic effect thus uncovering the physical nature of activation energies. While in the free Thymine electronic polarization and transfer processes are present separately, in the Mg(II) coordinated Thymine both effects are observed simultaneously and are localized on the ring in the molecular topology. It is argued that the difference in the charge transfer mechanism leads to a more stable enol form in the Mg(II) coordinated Thymine.
Identification of Anthocyanins in Red Grape, Plum and Capulin by MALDI-ToF MS
Authors: Castañeda-Ovando Araceli , Sedo Ondra , Havel Josef , Pacheco Lourdes , Galán-Vidal Carlos Andrés , Contreras López Elizabeth
Published: April 2018

A simple and fast method was developed to identify anthocyanins in red grapes, plums and capulins by MALDI-ToF MS. Three different matrices were used: α-CHCA (α-cyano-4-hydroxycinnamic acid), THA (2’,4’,6’-trihydroxyacetophenone) and DHBA (2,5-dihydroxybenzoic acid). Post-Source Decay (PSD) fragment detection allowed studying the structure of compounds detected. Deprotonated anthocyanin species were assigned in capulin ([Cyanidin-3-glucosidedeprotonated] K+ and [Cyanidin-3-rutinoside-deprotonated]K+), due to these compounds also can be ionized in form of potassium adducts combined with a deprotonation.
Chiral Enzymatic Activity in Cell Cultures of Taxus Species
Authors: Beatriz Alpízar Carmen , Díaz Eduardo , Sánchez-Obregón Rubén , Barrios Héctor , Sandoval Consuelo
Published: April 2018

Plant cell suspension cultures of Taxus brevifolia and Taxus globosa were used as biocatalysts on an exogenous racemic substrate in order to determine the influence of several parameters on its configurational deracemization bioactivity. Taxus brevifolia demonstrated a directly proportional relationship between the enantiomeric ratio (er) [1] and the time of reaction, yielding a mixture of 90(S):10(R) after 7 days. Pure enantiomers were tested and the results showed that the (S)-enantiomer remained intact, whereas the (R)-enantiomer was biotransformed. The buffer solution did not present any effect. Sucrose and temperature modified the reaction time and the er. The pH was a critical variable in relation to the age of the suspension cultures. Taxus globosa showed a low efficiency for distinguishing between the enantiomers.
Efficient Synthesis of 12-Aryl-8,9,10,12-tetrahydrobenzo[a]-xanthen-11-ones using Ionic Liquid Pyrazinium Di(hydrogen sulfate) {Py(HSO4)2} as a Novel, Green and Homogeneous Catalyst
Authors: Zare Abdolkarim , Khanivar Roghayyeh , Hatami Marzieh , Mokhlesi Mohammad , Zolfigol Mohammad Ali , Moosavi-Zare Ahmad Reza , Hasaninejad Alireza , Khazaei Ardeshir , Khakyzadeh Vahid
Published: April 2018

An efficient and simple solvent-free procedure for the synthesis of 12-aryl-8,9,10,12-tetrahydrobenzo[a]-xanthen-11-one derivatives via the one-pot multi-component condensation of dimedone with aromatic aldehydes and β-naphthol in the presence of protic acidic ionic liquid pyrazinium di(hydrogen sulfate) {Py(HSO4)2} as a green and homogeneous catalyst is described. All reactions proceed efficiently, and the title compounds are produced in high yields and in short reaction times.
ZnO Nanoparticles: A Highly Effective and Readily Recyclable Catalyst for the One-Pot Synthesis of 1,8-dioxo-decahydroacridine and 1,8-dioxooctahydro-xanthene Derivatives
Authors: Safaei-Ghomi Javad , Ghasemzadeh Mohammad Ali , Zahedi Safura
Published: April 2018

ZnO nanoparticles as a worthwhile and recyclable catalyst have been used for the one-pot synthesis of 1,8-dioxo-decahydroacridines and 1,8-dioxooctahydro-xanthenes via multi-component reactions under solvent-free conditions. The presented method is mild, environmentally friendly, inexpensive and highly effective to give the products in good to excellent yields.
Sesquiterpenes and Other Natural Products from Roldana reticulata
Authors: Arciniegas Amira , Maldonado Jhon Ironzi , González Karina , Pérez-Castorena Ana L. , Villaseñor José Luis , Romo de Vivar Alfonso
Published: April 2018

De Roldana reticulata se aislaron dos 9-oxo-furanoeremofilanos (1, 2), además de senecrassidiol, tirosol, icarisida D2 y rutina; no se detectaron alcaloides pirrolizidínicos, coincidiendo con el patrón químico del género reportado hasta ahora. La actividad anti-inflamatoria de los extractos y productos aislados fue evaluada en el modelo de edema de inflamación aguda inducido con TPA.
A Brief Performance Test of the M06 Family of Density Functionals for the Prediction of the Maximum Absorption Wavelength of Thioindigo in Several Solvents
Authors: Cervantes-Navarro Francisco , Glossman-Mitnik Daniel
Published: April 2018

The Minnesota family of density functionals (M06, M06L, M06-2X and M06-HF) has been used to calculate the UV-Vis spectra of the thioindigo molecule in solvents of different polarities using time-dependent density functional theory (TD-DFT) and the polarized continuum model (PCM). The maximum absorbance wavelengths predicted for each functional were compared with the known experimental results.
Favorable Direction in a Chemical Reaction Through the Maximum Hardness Principle
Authors: Pan Sudip , Chattaraj Pratim K.
Published: April 2018

Recently, an assessment regarding the validity of maximum hardness principle has been done taking 34 exothermic chemical reactions (Poater, J.; Swart, M.; Solà, M. J. Mex. Chem. Soc. 2012, 56, 311) in which only 46% and 53% of the total reactions have greater hardness for the products and the reactants than those for the reactants and the transition states, respectively. They have also mentioned that a larger set of reactions should be studied to draw a general conclusion regarding the validity of maximum hardness principle. We have noticed that the reactions having fewer number of reactants than that of products and / or very hard atoms like H, N, O, F or very hard molecules like H2, N2, HF, HCN, CH4, etc. appearing in the reactant side, are more likely to disobey maximum hardness principle. In addition, dependence of hardness values on level of theory, basis sets, definitions, formulas, approximations should be kept in mind before criticising the validity of maximum hardness principle. Since these electronic structure principles are qualitative in nature, one should not expect them to be valid in all cases.
Conophthorin from Almond Host Plant and Fungal Spores and Its Ecological Relation to Navel Orangeworm: a Natural Products Chemist’s Perspective
Authors: Beck John J.
Published: April 2018

The navel orangeworm (Amyelois transitella) is a major insect pest that brings about significant monetary damage to California tree nuts – almonds, pistachios, and walnuts. During their development, larvae of navel orangeworm feed upon the meat of these nuts causing physical damage and ultimately lowering kernel quality. Moreover, the larvae have been purported to vector aflatoxigenic fungi into the food product and thus represent a serious food safety concern. Aflatoxins are toxic metabolites produced by certain aspergilli – specifically for California tree nuts, Aspergillus flavus and Aspergillus parasiticus. Volatiles have played a large role in efforts to control or monitor navel orangeworm moths. For instance, a blend of almond host plant volatiles has recently been found to attract both male and female navel orangeworm moths during field trapping studies. The origin of many of the components within this host plant blend appears to be from the almond host. However, new reports regarding the blend component, conophthorin, imply a fungal origin for this particular volatile. This perspective discusses current investigations directly related to the production of conophthorin, and proposes a new relationship among navel orangeworm, the almond host plant, and ubiquitous tree nut orchard fungi.
Hydrothermal Synthesis of Mesoporous Silica MCM-41 Using Commercial Sodium Silicate
Authors: Meléndez-Ortiz Héctor Iván , Mercado-Silva Alfonso , García-Cerda Luis Alfonso , Castruita Griselda , Perera-Mercado Yibran Argenis
Published: April 2018

In this work, ordered mesoporous silica MCM-41 was prepared by hydrothermal synthesis using industrial-grade sodium silicate (Na2SiO3) as silica source, hexadecyltrimethyl-ammonium bromide (CTAB) as template agent and ethyl acetate as pH regulator. The influence of CTAB/SiO2 molar ratio, reaction time, aging temperature, and co-surfactant type on the structural and morphological properties of the obtained silica was studied. The roducts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and nitrogen adsorption-desorption isotherms. Ordered mesoporous MCM-41 silica was obtained at 80 °C by using a range of CTAB/SiO2 molar ratio from 0.35 to 0.71 and reaction times up to 72 h and isopropanol (i-PrOH) as cosurfactant.
Application of Programmed Temperature Vaporization Large Volume Injection Gas Chromatography (PTV-LVI-GC) to the Analysis of Polycyclic Aromatic Hydrocarbons (PAHs) in Soils
Authors: Delgadillo-Marín Miguel Ángel , Peña-Álvarez Araceli , Villalobos Mario Villalobos
Published: April 2018

A sensitive, selective and robust method was developed to quantify low levels of polycyclic aromatic hydrocarbons (PAHs) in soils by means of Programmed Temperature Vaporization - Large Volume Injection (PTV-LVI) coupled to gas chromatography with flame ionization detection. Optimal vent pressure and flux at the PTV inlet of the GC system were determined by comparison of peak areas obtained from injection of a standard PAHs mixture at different conditions. Assessment of method performance was carried out with home-made standards prepared by spiking three non-PAH contaminated soils that contained 1.8%, 4.6% and 25% natural organic matter (NOM), with mixtures of six different PAHs at low concentration levels. Detection limits between 9 and 12 ng g-1 and variation coefficients below 11% were determined from analysis of spiked samples of the soil with lowest NOM content. PAHs recoveries typically ranged from 61% to 96% for the three studied soils.
Reaction Between 7-Hydroxy Coumarin, Alkyl Isocyanides and Dialkyl Acetylenedicarboxylate: Synthesis of 4H-Chromenes and 1-Azabuta-1,3-dienes
Authors: Mohtat Bita , Farsijani Saeedeh , Razaghi Maryam , Djahaniani Hoorieh
Published: April 2018

The reactive intermediate generated by the addition of tert-butyl and 1,1,3,3-tetramethyl butyl isocyanide to dialkyl acetylenedicarboxylate was trapped by 7-hydroxycoumarin to produce highly functionalized 4H-chromenes in fairly good yields. When the reaction is performed with cyclohexyl isocyanide, 1-azabuta-1,3-dienes were obtained.