Judul: Peranan Kopi Dekafeinasi dalam Menurunkan Risiko Hipertensi : Sebuah Tinjauan Sistematis
Abstrak: Hypertension or increased blood pressure is a degenerative disease with a high prevalence, as well as the biggest cause of premature death in the world. Meanwhile, coffee is a popular and most consumed beverage around the world. Coffee can harm some people with certain health problems including hypertension due to its caffeine content. Decaffeinated coffee is known to be an alternative for people with hypertension with reduced caffeine content up to 97%. However, studies on the role of decaffeinated coffee in decreasing the risk of hypertension are still varied, indicated a systematic review is needed. This study uses a systematic review method to summarize the evidence related to the effect of decaffeinated and regular coffee on the risk of hypertension using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The inclusion criteria for scientific journals were determined based on Participants, Intervention, Control, Outcome (PICO). The search using boolean operation resulted in 13 research articles for data extraction. The result revealed that decaffeinated coffee varied between it could decrease or did not give any effect on blood pressure or another biological hypertension marker compared to regular coffee., Hipertensi atau peningkatan tekanan darah merupakan penyakit degeneratif dengan prevalensi tinggi, sekaligus penyebab kematian dini terbesar di dunia. Sedangkan kopi merupakan minuman yang populer dan paling banyak dikonsumsi di seluruh dunia. Kopi dapat membahayakan sebagian orang dengan masalah kesehatan tertentu termasuk hipertensi karena kandungan kafeinnya. Kopi tanpa kafein diketahui bisa menjadi alternatif bagi penderita hipertensi dengan kandungan kafein yang berkurang hingga 97%. Namun, penelitian tentang pengaruh kopi dekafeinasi dalam menurunkan risiko hipertensi masih bervariasi, mengindikasikan perlu dilakukan tinjauan sistematis. Penelitian ini menggunakan metode tinjauan sistematis untuk meringkas hasil penelitian terkait efek kopi tanpa kafein dan kopi biasa terhadap risiko hipertensi menggunakan Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Kriteria inklusi untuk jurnal ilmiah ditentukan berdasarkan Peserta, Intervensi, Pengendalian, Hasil (PICO). Pencarian menggunakan operasi boolean menghasilkan 13 artikel penelitian untuk ekstraksi data. Hasil penelitian menunjukkan bahwa kopi tanpa kafein memberikan efek yang bervariasi antara dapat menurunkan atau tidak berpengaruh pada tekanan darah atau penanda hipertensi biologis lainnya dibandingkan kopi biasa.
Keyword: Coffee, Decaffeinated coffee, Hypertension, Systematic review, Regular coffee

Judul: Meta-analysis Effect of Types, Roasting Levels, and Origins of Coffee on Antioxidant Activity
Abstrak: Selama sepuluh tahun terakhir, kopi telah menjadi objek penelitian yang banyak diminati untuk diteliti. Sejumlah penelitian tentang pengaruh jenis, tingkat roasting, suhu dan waktu roasting, dan negara asal kopi terhadap aktivitas antioksidan menghasilkan kesimpulan yang bervariasi. Meta-analisis adalah sebuah metode untuk merangkum berbagai hasil penelitian dengan topik sejenis secara kuantitatif untuk mendapat suatu kesimpulan. Penelitian ini bertujuan mengidentifikasi jenis, tingkat roasting, suhu dan waktu roasting, serta negara asal kopi yang menghasilkan aktivitas antioksidan tertinggi melalui meta-analisis. Meta-analisis dilakukan melalui tahapan, pencarian literatur pada database ilmiah, seleksi literatur berdasarkan kriteria inklusi, pembuatan basis data, analisis data, dan interpretasi hasil. Meta-analisis dilakukan dengan melakukan analisis sub kelompok. Berdasarkan hasil meta-analisis, jenis kopi, tingkat roasting, suhu dan waktu roasting, serta negara asal biji kopi dapat berpengaruh terhadap aktivitas antioksidan kopi. Hasil meta-analisis menunjukkan bahwa kopi Arabika memiliki aktivitas antioksidan lebih tinggi dalum uji FRAP dan ABTS. Perbedaan hasil antar uji antioksidan disebabkan oleh perbedaan mekanisme setiap metode uji antioksidan atau kandungan senyawa kopi dalam menangkal radikal bebas. Tingkat roasting light menghasilkan antioksidan lebih tinggi dari dark dalam uji FRAP dan DPPH persen inhibisi. Parameter suhu roasting yang disarankan adalah 147–205oC dan pengaturan waktu roasting dengan tingkat light atau medium. Kopi yang berasal dari Brazil dan India menghasilkan biji kopi dengan aktivitas antioksidan lebih tinggi dibandingkan negara lain., Over the last ten years, coffee has become the object of research that is in great demand for research. Several studies on the effect of type, roasting level, roasting temperature and time, and country of origin of coffee on antioxidant activity yielded varying conclusions. Meta-analysis is a quantitative method for summarizing various research results on similar topics to get a conclusion. This study aims to identify the type, roasting level, roasting temperature and time, as well as the country of origin of coffee that produces the highest antioxidant activity through meta-analysis. Meta-analysis was carried out through stages, literature search in scientific databases, literature selection based on inclusion criteria, database creation, data analysis, and interpretation of results. Meta-analysis was carried out by conducting subgroup analysis. Based on the results of the meta-analysis, the type of coffee, roasting level, roasting temperature and time, and the coffee beans country of origin can affect the coffee's antioxidant activity. The meta-analysis results showed that Arabica coffee had higher antioxidant activity in the FRAP and ABTS assays. The difference in the results between antioxidant tests is caused by the different mechanisms of each antioxidant test method or the content of coffee compounds in counteracting free radicals. Light roasted coffee beans exhibited higher antioxidant activity than dark roasted beans in FRAP and DPPH assays. The recommended roasting temperature parameter is 147–205oC and the roasting time setting is light or medium. Coffee originating from Brazil and India produces coffee beans with higher antioxidant activity than in other countries.
Keyword: antioxidant activity, coffee types, country origin of coffee, meta-analysis, time and temperature roasting

Judul: Penentuan Nilai Eigen dan Vektor Eigen dari Matriks Tridiagonal 2-Toeplitz dengan Pendekatan Polinomial Chebyshev
Abstrak: The eigenvalues and eigenvectors of a matrix can be determined by finding its characteristic polynomials. The characteristic polynomials of a tridiagonal 2-Toeplitz matrix is shown to be closely connected to polynomials which satisfy the Chebyshev recurrence relationship. If the order of the matrix is odd, then the eigenvalues are found explicitly in terms of the Chebyshev zeros and the eigenvectors are found in terms of the polynomials satisfying the recurrence relationship. For even ordered matrices, the situation is more complicated. The problem in these cases is that although the Chebyshev recurrence formula is still applied, its initial values are not generating Chebyshev polynomials
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