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"Hidrogen berpotensi besar sebagai energi masa depan, namun untuk metode penyimpanannya yang efektif masih menjadi tantangan. Penyimpanan bentuk gas membutuhkan vessel yang tahan tekanan setinggi 350 bar dan bentuk cair memerlukan suhu dibawah –239,95°C, sehingga butuh insulasi yang sulit. Pada November 2022, tim peneliti dari Jerman, Henrik dkk., mengembangkan metode penyimpanan dan pelepasan hidrogen dengan menggunakan reaksi kesetimbangan bikarbonat-format yang dibantu oleh katalis (4-Me)Triaz(NHPiPr2)2Mn(CO)2Br. Katalis tersebut berbasis mangan yang merupakan logam paling berlimpah kedua di bumi, tidak beracun, dan ramah lingkungan. Dalam penelitian ini kami mengusulkan tiga mekanisme reaksi yang memungkinkan untuk sistem penyimpanan dan pelepasan hidrogen ini bekerja. Kami menggunakan teori fungsional kerapatan (density functional theory, DFT) untuk memahami reaksi ini pada tingkat molekuler. Barrier single point energy paling rendah didapat pada mekanisme III, yaitu mekanisme yang dimana tahapan penentu laju reaksinya adalah pelepasan ion format dari katalis Mn bermuatan netral dengan nilai sebesar 24,9 kkal/mol dihitung pada tingkatan teori B3LYP-D3 def2-TZVP/SMD(THF). Selain itu, ditemukan bahwa penggunaan campuran air dan THF sebagai pelarut memberikan hasil yang lebih baik lagi. Tahapan penentu laju dari mekanisme ini ialah tahap pelepasan ion format dari pusat logam katalis dengan perubahan energi bebas Gibbs sebesar 8,9 kkal/mol. Semua perhitungan dilakukan dengan menggunakan perangkat lunak ORCA 5.0.3, Chemcraft dan Avogadro.......Hydrogen has great potential as a future energy, but effective storage methods still pose a challenge. Gas storage requires a vessel that can withstand pressures as high as 350 bar and liquid form requires temperatures below –239.95°C, necessitating difficult insulation. In November 2022, a team of researchers from Germany, Henrik et al., developed a storage and release method for hydrogen using the bicarbonate-formate equilibrium reaction assisted by the catalyst (4-Me)Triaz(NHPiPr2)2Mn(CO)2Br. This catalyst is based on manganese, the second most abundant metal on Earth, which is non-toxic and environmentally friendly. In this study, we propose three reaction mechanisms that allow this hydrogen storage and release system to function. We employ density functional theory (DFT) to understand these reactions at the molecular level. The mechanism with the lowest single-point energy barrier is found in mechanism III, where the rate-determining step is the release of the formate ion from the neutral-charged Mn catalyst, with a value of 24.9 kcal/mol calculated at the B3LYP-D3 def2-TZVP/SMD(THF) level of theory. Furthermore, it is found that using a mixture of water and THF as a solvent yields even better results. The rate-determining step of this mechanism is the release of the formate ion from the central metal catalyst, with a change in Gibbs free energy of 8.9 kcal/mol. All calculations were performed using the software packages ORCA 5.0.3, Chemcraft, and Avogadro."

"This book focuses on state-of-the-art methods and applications of electron-density analysis. It is a field traditionally associated with understanding chemical bonding and the electrostatic properties of matter. Recently, it has also been related to predictions of properties and responses of materials (having an organic, inorganic or hybrid nature as in modern materials and bio-science, and used for functional devices or biomaterials)."

"This book about more than just distances from electron density studies, modeling and analysis of hydrogen atoms, charge density methods in hydrogen bond studies. some main group chemical perceptions in the light of experimental charge density investigations. electronic structure and chemical properties of lithium organics seen through the glasses of charge density. bond orders in metal–metal interactions through electron density analysis, and on the nature of β-agostic interactions : a comparison between the molecular orbital and charge density picture."

"This book about new directions in pseudoatom-based X-ray charge density analysis, reliable measurements of dipole moments from single-crystal diffraction data and assessment of an in-crystal enhancement, challenging problems in charge density determination : polar bonds and influence of the environment, electron density in quantum theory, residual density analysis, the source function descriptor as a tool to extract chemical information from theoretical and experimental electron densities."

"ABSTRAKPenelitian ini membahas mengenai studi kelayakan material ekuivalen jaringan spesifik pada rentang energi radiodiagnostik 80 kV hingga 130 kV , yang dikontruksi menggunakan campuran bahan organik berupa tepung beras dan lilin batik gondorukem, cecek, parafin . Dari hasil studi pendahuluan, didapatkan 4 jenis komposisi material ekuivalen, yaitu material ekuivalen jaringan adiposa, jaringan otot, jaringan otak dan organ hati. Masing-masing komposisi material ekuivalen jaringan kemudian akan melalui dua jenis metode uji, yaitu metode Dual Energy Computed Tomography DECT untuk mengetahui karakteristik sampel melalui besaran Hounsfield Unit HU, dan metode stoikiometri menggunakan Energy Dispersive Spectroscopy EDS untuk mengetahui karakteristik sampel melalui susunan jenis atom. Masing-masing data dari kedua metode kemudian akan diolah hingga mendapat nilai densitas elektron ?e dan nomor atom efektif Zeff . Hasil kalkulasi untuk metode uji DECT pada material ekuivalen jaringan adiposa, jaringan otot, jaringan otak dan organ hati menunjukan kesalahan literatur minimum sebesar 0,605 ; 0,732 ; 0,751 ; 0,670 untuk densitas elektron ?e dan 26,345 ; 26,417 ; 25,089 ; 24,617 untuk nomor atom efektif Zeff. Sedangkan untuk metode Stoikiometri, pengukuran dianggap tidak akurat karena atom hidrogen yang tidak dapat terdeteksi. Dari hasil tersebut, dapat disimpulkan bahwa tingkat akurasi metode DECT lebih baik dibandingkan metode stoikiometri, dengan hasil analisa dari keempat sampel menunjukan kesesuaian respon terhadap jaringan target, namun hanya pada jenis energi tinggi 130kV.

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ABSTRACTThis research discusses the feasibility study of tissue specific equivalent material in radiodiagnostic energy range 80 kV to 130 kV, that are made from organic mixtures rice flour and waxes for batik gondorukem, cecek, paraffin . From the preliminary study, we obtain four types of equivalent material compositions, which are equivalent to adipose, muscle, brain, and liver. Each of the compositions will be evaluated using two methods, which is Dual Energy Computed Tomography DECT method in order to discover characteristic through Hounsfield Unit HU scale, and Stoichiometry with Energy Dispersive Spectroscopy EDS in order to discover characteristic through atoms composition. The test result then processed into the quantity of electron density e and effective atomic number Zeff . From DECT method, calculation of adipose, muscle, brain, and liver equivalent materials shows minimum literature error 0,605 0,732 0,751 0,670 for electron density e and 26,345 26,417 25,089 24,617 for effective atomic number Zeff . While for the Stoichiometric method, the measurement is considered inaccurate because the hydrogen atom cannot be detected. From these results, it can be concluded that the DECT method has better accuracy compared to stoichiometry method, which the four samples have a similar response that represents tissue target, but only when exposed with high energy 130kV ."