In mainstream writing there is a bit more flexibility. When used with care and in the right context, it may be fine to begin a sentence with a conjunction like and or but and not fear the wrath of your pedantic friends. However, scientific writing tends to be more formal and traditional, so sentences beginning with and or but should be avoided altogether.
How about sentences beginning with due to, because, or however?
First off, because due to is essentially synonymous with caused by, it is almost always grammatically incorrect at the beginning of a sentence. Even if you were to construct a grammatically defensible sentence, such as “Due to decades of smoking, his emphysema worsened to the point that he needed an oxygen tank.”, it would still be more awkward and less clear than simply saying “His emphysema, caused by decades of smoking, worsened to the point that he needed an oxygen tank.” In short, avoid starting a sentence with due to.
Many of our teachers taught us not to begin a sentence with because. However, there really is no rule against beginning your sentence with because. Take care to use it sparingly and appropriately, however, to avoid giving your paper a choppy feel when reading.
Because of the low light conditions and abnormal amounts of rain, only 42% of the seeds sown in the test plots germinated.
Because retinitis pigmentosa is only one of the leading causes of vision loss, we undertook this retrospective study.
As with because, there is nothing wrong with beginning a sentence with however, but the new sentence should always relate to the sentence preceding it (e.g., do not begin a sentence with however at the beginning of a new paragraph).
Fifteen of the saplings in the test plot were free of Pucciniales infection, 4 had minor lesions, and 6 had severe lesions at the end of the test period. However, all of the saplings with lesions showed good growth.
Fifteen of the saplings in the test plot were free of Pucciniales infection, 4 had minor lesions, and 6 had severe lesions at the end of the test period. However, two saplings were also infected with root rot.
It’s also important to make sure you essentially always follow however with a comma.
Muffin had six kittens over the weekend. However we tried to give them away.
Note that without the comma, the sentence is confusing. The reader may expect the sentence to continue. For example, “However we tried to give them away, we couldn’t find new homes for all the kittens.”
Of course, if your two sentences are very strongly linked, you may wish to join them as a single sentence broken up with a semicolon. In these cases, the comma after however is still needed.
Muffin had six kittens over the weekend; however, we tried to give them away.
Grammar and punctuation are among the top reasons for being rejected by a journal. To ensure the language in your manuscript is publication-ready you should have a native-English-speaking expert in your field edit for grammar, clarity, and accuracy of scientific expression.