Judul: Fenomena Overreaction Jangka Pendek Saham Syariah di Indonesia terhadap COVID-19
Abstrak: COVID-19 merupakan peristiwa yang menimbulkan dampak buruk di berbagai sektor salah satunya adalah sektor pasar modal. Kondisi ketidakpastian yang tinggi akibat mewabahnya COVID-19 menyebabkan investor bereaksi terhadap peristiwa tersebut sehingga dapat menimbulkan fenomena overreaction. Peristiwa yang diambil dalam sampel penelitian ini sejumlah tujuh peristiwa terkait COVID-19. Penelitian ini bertujuan untuk menganalisis fenomena overreaction pada saham syariah dan faktor yang memengaruhinya dengan menggunakan metode uji beda dan cross sectional regression. Hasil penelitian menunjukkan bahwa Pengumuman transmisi COVID-19 dan lockdown (Event 2) menyebabkan overreaction pada saham winner. Fenomena overreaction saham loser disebabkan oleh pengumuman stimulus fiskal Amerika Serikat (Event 5) dan pengumuman PSBB (Event 6). Peristiwa pengumuman new normal (Event 7) menyebabkan saham winner maupun loser mengalami overreaction. Faktor yang memengaruhi fenomena overreaction pada peristiwa tersebut terbukti secara signifikan dan berhubungan negatif adalah leverage dan kapitalisasi pasar, sedangkan volume perdagangan secara signifikan memengaruhi dan memiliki hubungan positif dengan fenomena overreaction., COVID-19 is an event that has harmed various sectors, one of which is the capital market sector. The high uncertainty caused by the COVID-19 outbreak caused investors to react to this event, which could cause an overreaction phenomenon. The events taken in this study sample are seven events related to COVID-19. This study aims to analyze the phenomenon of overreaction in Islamic stocks and the factors that influence the phenomenon of overreaction by using the two-sample difference test method and cross-sectional regression. The results showed that the announcement of COVID-19 transmission and lockdown (Event 2) caused overreaction in winner stocks. The phenomenon of loser stock overreaction was caused by the announcement of the United States fiscal stimulus (Event 5) and the announcement of the PSBB (Event 6). The new normal announcement event (Event 7) caused Islamic stocks both winner and loser to experience overreaction. The factors that influence the overreaction phenomenon in this event are proven to be significantly and negatively influenced by leverage and market capitalization, while trading volume had a significant effect and positively influence the overreaction phenomenon.
Keyword: COVID-19, cross sectional regression, overreaction

Judul: Fenomena Overreaction Jangka Pendek Saham Syariah Indonesia selama Pandemi COVID-19
Abstrak: Pandemi COVID-19 merupakan peristiwa luar biasa yang tidak terduga. Krisis kesehatan tersebut berakibat pada perekonomian global tanpa terkecuali pasar saham syariah Indonesia. Goncangan pada pasar saham syariah menyebabkan ketidakpastian dan perubahan perilaku para investor yang berpotensi terjadi anomali overreaction. Penelitian ini bertujuan untuk menganalisis fenomena tersebut pada pasar saham syariah Indonesia. Metode analisis yang digunakan adalah uji beda dan cross sectional regression. Indeks yang digunakan adalah Jakarta Islamic Index (JII). Hasil penelitian menunjukkan bahwa peristiwa dilantiknya Joe Biden sebagai presiden Amerika Serikat selama Pandemi COVID-19 (Event 8) dan peristiwa kenaikan kasus kematian harian tertinggi akibat COVID-19 (Event 11) secara signifikan terjadi overreaction pada saham-saham kategori winner. Faktor yang memengaruhi overreaction tersebut adalah kapitalisasi pasar yang secara signifikan berpengaruh positif dengan overreaction. Selain itu, volume perdagangan secara signifikan berpengaruh negatif dengan terjadinya overreaction., The COVID-19 pandemic is an unexpected and extraordinary event. The health crisis has had an impact on the global economy without exception, including the Indonesian Sharia stock market. The shock in the Sharia stock markets has caused uncertainty and a change in the behavior of investors that could potentially lead to an anomaly of overreaction. The study aims to analyze the phenomenon in the Indonesian Sharia stock market. The analytical methods used are differential tests and cross-sectional regression. The index used is the Jakarta Islamic Index (JII). The results of the study showed that Joe Biden's appointment as president of the United States during the COVID-19 pandemic (Event 8) and the increase in daily deaths due to COVID-19 (Event 11) significantly overreacted to the winner category stocks. The factor that influences such overreactions is market capitalization, which significantly influences overreaction. Besides, trading volumes negatively influenced overreaction.
Keyword: COVID-19, Cross Sectional Regression, Islamic Stock Market, Overreaction

Judul: Synthesis of Apatite - Chitosan Composite Using Duck Eggshell and Chitosan with Temperature and pH Control
Abstrak: Composite of apatite-chitosan was prepared by using chitosan as polymer matrix. Calcium phosphate was prepared from CaO and (NH4)2HPO4, which the ratio Ca : P had to be 1.67. Chitosan is produced by deacetilase from biopolymer chitin. Duck eggshell (95% CaCO3) as starting material was converted to be calcium oxide (CaO) through calcinations with temperature 1000oC for 5 hours. In-situ and ex-situ methods were prepared from apatite and chitosan (dissolved with acetate acid 2%). Calcium phosphate prepared for bone implantation, but it is too fragile and brittle to be implant into the body. So addition of chitosan can decrease crystalinity and increase mechanic characteristic (tougher). Composite apatite-chitosan was resulted by fast precipitation. Fast precipitation was held in a breaker glass with nitrogen atmosphere, under controlled temperature at 37oC and pH 7, in order to increase amount of hydroxyapatite. Precipitation with CaO which was dropped by (NH4)2HPO4. Hydroxyapatite and chitosan were appearing at samples with in-situ and ex-situ methods which indicating by peak matching of XRD (closed lattice parameter, crystal size), overlapping at FTIR spectra and supporting by SEM picture (homogenous and agglomerated particle). However, it still needs further research to examine biocompatibility osteoconductive degree of sample by in-vivo and in-vitro test.
Keyword: