One-dimensional nanostructures of gamma alumina exhibiting excellent properties such as a large surface area and high porosity are widely used as catalysts and adsorbents and in other applications. Here, we report the effect of ultrasound treatment on infrared spectrum, mineral phase, morphology, and textural properties of gamma alumina nanorods, which were successfully synthesized from salt-starch precursors through a facile precipitation method. We used aluminum ammonium carbonate hydroxide-starch derived from aluminum nitrate at pH 9 and a 2% (w/v) starch slurry, under normal conditions with ultrasound treatment as a precursor. The as-synthesized alumina were then calcined at 600°C. We observed the infra-red spectrum of the assynthesized alumina treated by ultrasound show typical absorption bands of functional that groups. Ultrasonically treated assynthesized alumina at 600°C consist of a pure gamma alumina phase with higher intensity and a microstructure of nanorod-like shapes with aspect ratios of 217.5, indicating a mesoporous material, and exhibit a higher specific surface area and pore volume than that of alumina synthesized under normal conditions.

No abstract

enis dan perubahan warna bone ash sintetik Balai Besar Keramik berdasarkan suhu kalsinasi secara visual adalah putih. Pada penelitian ini sifat kromatik warna bone ash sintetik ditentukan berdasarkan sistem CIELAB untuk mengetahui perubahan warna yang lebih objektif dan menghasilkan nilai yang terukur. Bone ash sintetik dikalsinasi dengan variasi suhu antara 600 o C -1250 o C. Masing-masing hasil kalsinasi dijadikan aplikasi glasir ubin pada suhu 1170 o C. Panjang gelombang bone ash sintetik kalsinasi 492-574nm dan glasir bone ash 477-542nm, berarti termasuk material putih. Derajat whiteness dan brightness mengalami penurunan dengan nilai terbesar pada bone ash kalsinasi 1250 o C, whiteness = -59,90% dan brightness = -61,42%. Berdasarkan nilai L*, a* dan b* ruang warna bone ash sintetik bergeser dari Hijau Kuning menjadi Hijau Biru dan indeks whiteness bergeser menuju hitam.

Psychological well-being sebagai prasyarat untuk work engagement melalui ekspresi sumber daya fisik, kognitif dan emosional. Hal ini, mengacu pada keadaan bahagia dalam tugas kerja. Tujuan penelitian ini adalah untuk menganalisis pengaruh occupational stress dan psychological contract terhadap work engagement melalui psychological well being sebagai variabel intervening. Sampel dari penelitian ini adalah sebanyak 33 orang dari populasi 33 pegawai KCP Bank Jateng Pasar Johar. Metode penentuan sampel menggunakan sampling jenuh. Analisis data menggunakan model regresi linier berganda dengan dua model dan uji sobel. Hasil pengujian hipotesis model pertama menunjukkan occupational stress secara statistik berpengaruh negatif dan signifikan terhadap psychological well being dan psychological contract secara statistik berpengaruh positif dan signifikan terhadap psychological well being. Hasil pengujian hipotesis model kedua menunjukkan bahwa psychological well being secara statistik berpengaruh positif dan signifikan terhadap work engagement, occupational stress secara statistik berpengaruh negatif dan signifikan terhadap work engagement dan psychological contract secara statistik berpengaruh positif dan signifikan terhadap work engagement. Hasil pengujian hipotesis menunjukkan bahwa occupational stress secara perhitungan sobel  bahwa ada  pengaruh tidak langsung terhadap work engagement yaitu melalui psychological well being sebagai variabel intervening dan psychological contract secara perhitungan sobel  bahwa ada  pengaruh tidak langsung terhadap work engagement yaitu melalui psychological well being sebagai variabel intervening

Background: Limestone primarily consists of CaCO3 (calcium carbonate), which have a similarity to one of human bone component, hydroxyapatite (HA), an element of apatite group (Ca10(PO4)6(OH)2). There were several setbacks in the use of artificial hydroxyapatite in the bone repair process; one of them was its relatively higher crystallinity level compared to those of human bone apatite. The addition of carbonate element to hydroxyapatite could improve its characteristics, such as increasing the solubility, decreasing the crystallinity, and changing the morphology of the crystal. That caused carbonate hydroxyapatite is preferable to help in the bone repair process. Aims: This study aimed to find the effect of limestone-based CHA on viability and proliferation of hUMSCs, thus discovering the potential of CHA as a bone graft biomaterial candidate derived from limestone. Methods: This study used FTIR, EDX, and XRD assays to CHA powder sample derived from limestone found in Padalarang and Cirebon extracted by BBK. Two grams of the sample were placed in the sample holder and examined by computer software. EDX assay was conducted three times in three different points, and the means were recorded. In the XRD assay, a carbon tip was put to the sample holder to allow sample attachment. The recorded data was compared to JCPDS data. Toxicity and proliferation examination of CHA were conducted through MTT assay in human umbilical cord mesenchymal stem cell (hUCMSC) cell lines with four different doses: 50µg/ml, 25µg/ml, 12,5µg/ml, and 6,25µg/ml. Results: Limestone-based CA has hydroxyl (OH-), phosphate (PO42-), and carbonate (CO32-) functional groups. It has crystal particle formation and consists of O, Ca, and P elements. The result of the MTT assay showed limestone-based CHA is not toxic in all concentrations and has the proliferative ability. There were significant differences between the control and treatment groups. Conclusion: CHA has OH-, PO42-, and CO32- function group. It has crystal particle formation and O, Ca, and P elements as its composition, with a Ca/P ratio of 1,67. It shows no toxicity to hUCMSC in all doses and has the ability to stimulate hUCMSC proliferation.