Juni – Juli, Tsuyu dan Hydrangea

(Oleh: Willy Yanto Wijaya)

Sekitar awal Juni hingga pertengahan Juli, datanglah musim hujan yang menyirami hampir seluruh wilayah Jepang, yang dikenal dengan sebutan 梅雨 (tsuyu). Wilayah utara Jepang seperti Hokkaido memang tidak mengalami tsuyu, dan wilayah selatan Jepang seperti Okinawa mengalami tsuyu lebih awal dibanding daerah Kanto (Tokyo dan sekitarnya). Tsuyu ini diakibatkan oleh tumbukan massa udara antara udara dingin dari utara dan udara hangat dari selatan. Ketika memasuki bulan Agustus, front udara hangat dari selatan semakin menguat dan akhirnya berhasil menekan mundur front udara dingin sehingga datanglah musim panas di Jepang yang lembab dan gerah. Dengan demikian, tsuyu adalah indikasi perubahan dari musim semi menjadi musim panas.

Selama beberapa pekan selama tsuyu, hampir setiap hari selalu turun hujan. Hujan di Jepang agak berbeda dengan hujan di Indonesia. Hujan di daerah tropis seperti Indonesia biasanya cukup lebat dan berlangsung singkat seperti dua atau tiga jam, sedangkan hujan di Jepang biasanya gerimis atau rerintikan tapi dapat berlangsung selama berjam-jam atau bahkan seharian.

Secara harafiah, tsuyu berarti “hujan plum”, dinamakan begitu karena matangnya buah plum (梅ume) bertepatan dengan datangnya tsuyu. Buah plum yang matang ini kemudian suka diolah menjadi umeboshi (buah plum yang di-asam-asin-kan) yang sering menemani bento (lunch box) orang Jepang.

Air hujan selama tsuyu ini juga memainkan peran yang sangat penting bagi penanaman padi, yang akan tumbuh pesat selama musim panas dan dipanen di musim gugur.

Walaupun selama tsuyu, cuaca sering berawan dan kelabu, jalanan pun basah dan agak becek, akan tetapi selama tsuyu inilah bunga hydrangea mekar dengan indahnya. Bunga hydrangea (hortensia) ini disebut “ajisai” dalam bahasa Jepang. Ada banyak jenis hydrangea, akan tetapi yang paling populer adalah species Hydrangea macrophylla. Species ini memiliki dua tipe subspecies yang paling lazim ditemukan, yaitu hydrangea mophead dan hydrangea lacecap seperti tampak pada foto. Pohon bunga hydrangea ini berupa perdu, dan sering ditanam di pagar atau pekarangan rumah. Yang unik dari hydrangea ini adalah warna bunganya yang bisa berubah antara biru ungu dan pink merah atau krim pucat tergantung tingkat pH (keasaman) tanah. Tanah yang agak asam menghasilkan bunga berwarna biru, yang agak basa menghasilkan warna pink atau ungu, dan tanah netral menghasilkan warna krim pucat.

Demikianlah sekilas gambaran mengenai musim hujan selama bulan Juni dan Juli di Jepang. Ya, paling tidak bunga-bunga hydrangea yang bermekaran indah merupakan pelipur lara terhadap cuaca kelam selama berlangsungnya tsuyu ini.

Hydrangea mophead berwarna biru

 

Hydrangea mophead berwarna pink keunguan

 

Hydrangea lacecap (salah satu varian)

Assembling the Fundamentals of Science for the Breakthrough in Fuel Cell Technology

(written by: Willy Yanto Wijaya)

Like the heat pump, fuel cell is an important technology in the energy utilization systems. Before the concept of fuel cell was invented, people utilized the chemical energy to be combusted and then this heat was converted into electricity through the turbine-generator system. Fuel cell, on the other hand, converts this chemical energy directly to the electricity energy thus shortening the energy conversion processes; and this means less exergy loss will occur. It can be said that fuel cell has avoided the irreversibility otherwise occurred in chemical-heat-electricity conversion processes. In this sense, intuitively we could expect that fuel cell will give a very high efficiency. However, why until now the efficiency of fuel cell is still in the range of 50-60%, just a little higher than the efficiency of power plant combustion system?

Fuel cell system is not without problems. Several to mention are the cost, durability, reactivity, losses and other thermal, water management and technical issues. To pick up a case, research has been done concerning the finding of alternatives to Pt catalyst that is expensive. However, to find suitable material to replace Pt is not an easy matter. This requires the knowledge and understanding of material properties, molecular interaction and various electro-chemical-physics parameters. The same case also happens to the questions such as: why the reactivity is slow and how to prolong the durability of membrane. These all require research in inter-disciplinary fields.

We can say that our fundamental understanding is still not “complete”, even still not “sufficient”. Like the Shirakawa Sensei story of Nobel Prize; he said that his discovery of the new material was due to the mistake of his student. His student added the catalyst 1000 times of the intended amount. This implies that actually we still don’t know very well the chemical reactions. There are so many chemical and physical parameters that work together in the actual system in the nature: the properties of material; aspect of particle geometry; various chemical substances; physical parameters such as temperature, pressure, magnetic field; etc.

Possibly we can view all these one-another interactions of these parameters like the sand pile. What we see are only average-statistical resultant of the deeper microscopic mechanisms. It is like the tiny bit of sand on the peak of the pile, supported by several tiny bits below. It is possibly the reasons why people in medicine/biology field can only memorize the outer macroscopic phenomena, since the living organism systems are so complex if they dig deeper into the microscopic mechanisms “sand pile”. This could be the reason why Roger Penrose thought that the realm of Biology can be reduced into the realm of Chemistry and further reduced into the realm of Physics.

Therefore, I think that attempts to keep documentation of each chemical-physical parameter and its interaction with myriad of other parameters are necessary. Of course, there will be enormously huge amount of data, interactions, and possibilities. Nevertheless, if this huge amount can be documented well, they can be more conveniently assembled and better research can be conducted. To connect to the fuel cell, right now, we can see many researchers are attempting to use alternative materials, such as alternative for Pt catalyst; NaBH₄ as the fuel for fuel cell, etc. Of course, to determine the choice, understanding about substance/material parameters is indispensable. Without this, only the “brute-force” efforts (trial and error) could be done, and most of these efforts will only die away since the probabilities of the choices are so enormous like the probabilities of the “Hanoi Tower” puzzle.

Fig. Schematic of a fuel cell car.